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33168 Publications

Bacterial and archaeal diversity in waters at the Siberian deep-well monitoring site Tomsk-7

Nedelkova, M.; Selenska-Pobell, S.;
Microbial diversity was studied in water samples collected at depths of 290 to 324 m from the monitoring site S15 near the city of Tomsk, Siberia, Russia. The 16S rDNA retrieval was applied, in order to overcome the problems of culturability of the bacteria and archaea indigenous for that extreme habitat. The biomass from the samples was concentrated via consequent filtration on a glass-fibre filter and on filters with pore sizes of 0.45 and 0.22 µm. In this work two bacterial clone libraries were analysed: one constructed for the DNA isolated from the biomass collected on the filter with a size of 0.45µm and another one for those of the 0.22µm filter. In addition, an archaeal clone library was generated for the total DNA extracted simultaneously from all the tree filters (unfractioned DNA). Comparative analyses of the two bacterial libraries revealed significant differences in the predominant groups and in the species composition. In the 0.45µm clone library a dominance of Dechlorosoma spp. populations was found. This result is in agreement with our previous study on bacterial diversity in water at the site S15 which was performed by using total unfractioned DNA (1). However, in contrast of that previous analysis, now the predominance of the Dechlorosoma spp. was not too strong and we were able to find a larger variety of species from: d-subclass of Proteobacteria, Gramm positive bacteria, and in addition members of Candidate divisions OP8, TM7 and the Termite group. In the 0.22µm clone library Dechlorosoma sp. was not identified any more. In this case populations of Chrysobacterium spp. from the Cytophaga/Flavobacterium/Bacteroides group were predominant. There were some common Proteobacterial and Actinobacterial species, which were identified in both the 0.45µm and the 0.22µm libraries. Interestingly, relatively dense and diverse populations of deeply branched not yet cultured Cyanobacteria were found in both bacterial clone libraries. The phylogenetic analysis of Archaeal populations in the S15 sample revealed the presence of sequences which belong to Crenarchaeota and Euryarchaeota. The members of the latter were methanogens and some of them were related to clones identified in metal-rich freshwaters by others (2). Most of the Crenarchaeota 16S rDNA sequences were also similar to those found in other metal-rich environments (3).
Our analysis indicates that microbial communities at the monitoring site S15 are rather complex and diverse. The 0.45µm clone library exhibits greater overall diversity than the 0.22µm clone library. The archaeal populations are represented mainly by clones affiliated with organisms found in other metal pollutd environments.

References:
1. Nedelkova, M., et al. (2003) Environmental Geology (in press).
2. Stein, L. et al. (2001) Env. Microb. 3(1) : 10-18.
3. Stein, L. et al. (2002) FEMS Microb. Ecol. 42 : 431-440.
  • Poster
    Workshop Umweltmikrobiologie Freiberg 5.-7.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5876
Publ.-Id: 5876


Uranium contaminated environments as a reservoir of unusual bacteria prospective for bioremediation and nanotechnology

Selenska-Pobell, S.;
Microbial communities were studied in several uranium mining wastes in Germany and in the USA by using the rDNA retrieval applying several sets of amplification primers flanking different regions of the rrn operons (1, 2). The bacterial populations in the studied soil samples were rather dense and extremely diverse. In the water samples a lower grade of bacterial diversity was found. Despite the fact that the composition of the bacterial communities was site-specific, several bacterial groups including also novel lineages seem to be characteristic for the studied heavy-metal-polluted environments. The archaeal populations, in contrast, were not very dense and were limited to several not yet cultured Crenarchaeotae lineages which were identified in other metal contaminated environments as well.
In parallel to the above mentioned direct molecular approach, the method of enrichment culturing was applied in order to recover and study particular bacterial strains indigenous for the U wastes. Bacterial isolates belonging to different species representing diverse bacterial groups were recovered and characterized (1). The resistance and the interactions of these isolates with U and with other heavy metals were demonstrated to be species- and even strain-specific. The atomic structures and the cellular location of the complexes formed with U(VI) by the isolates were studied using EXAFS spectroscopy, TEM, and EDX analyses. In all cases phosphate groups were predominantly implicated in the complexation of uranium but the structural parameters and the cellular location of the complexes differed between the studied bacterial groups (3).
Many of the studied strains possess unusual characteristics as the isolate JG-A12, for instance, which accumulates selectively U, Cu, Pb, Al, and Cd (4). This strain as well as its intrinsic S-layer are forming U(VI)-complexes with identical structural parameters in which phosphorous residues in addition to the carboxyl groups are involved. ICP-MS demonstrated that the S-layer of JG-A12 is phosphorylated. This can explain its high ability to complex uranium and other metals. The latter seems to give an advantage to the strain to survive in environments heavily polluted with uranium and other toxic metals from which it was recovered.
Sol-gel ceramics with high and reversible metal binding capacity were prepared via homogeneous dispersion and embedding of B. sphaericus JG-A12 vegetative cells (5, 6). This biological ceramics are very perspective for bioremediation of heavy metal contaminated water wastes.
In addition, Pd nanoclusters were also successfully grown on the surface of these bacteria. The latter is of interest for the nanotechnology. Interestingly, the above mentioned S-layer of JG-A12 possesses an unusual primary structure which indicates that lateral transfer was involved in the evolution of its gene.
References
1. Selenska-Pobell, S. (2002) Interactions of Microorganisms with Radionuclides p. 225-253; Elsevier, Oxford
2. Selenska-Pobell, S., et al. (2001) Antonie van Leeuwenhoek 79, 149-161.
3. Merroun M. et al. (2003) FZR-Report No. 364, p. 26-30
4. Selenska-Pobell, S. et al. (1999) FEMS Microbiol. Ecol. 29, 59-67
5. Raff, J. et al. (2003) Chem. Mater. 15 (1): 240-244.
6. Soltmann et al. (2003) J Sol-Gel Science and Technology 26, 1209-1212.
  • Lecture (Conference)
    Workshop Umweltmikrobiologie Freiberg 5.-7.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5875
Publ.-Id: 5875


Uranium mining waste pile isolate Bacillus sphaericus JG-A12 and its technological applications

Pollmann, K.; Raff, J.; Merroun, M.; Schnorpfeil, M.; Selenska-Pobell, S.;
The strain Bacillus sphaericus JG-A12 was isolated from a uranium mining waste pile near the town of Johanngeorgenstadt. The drain water and the soil of this environment are highly contaminated with heavy metals and radionuclides. The cells of B. sphaericus JG-A12 are capable of selective and reversible accumulation of U, Cu, Pb, Al, and Cd from the U waste waters (1). It was demonstrated that the strain JG-A12 is enveloped by a surface layer protein (S-layer) which differs significantly in its primary structure from the other B. sphaericus S-layers studied up to date (2). The highly ordered crystalline S-layers are one of the most common cell envelope structures of bacteria and archaea (3). They are composed of identical protein monomers which possess an ability to self-assemble into two-dimensional crystalline arrays. The highly regular structure of the S-layers with many pores of identical size offers good binding sites for many different metals and nucleation sites for the formation of metal nanoclusters or minerals. EXAFS-analyses of the uranium complexes formed by the S-layer of JG-A12 showed that this metal is coordinated to carboxyl and phosphate groups of the latter (4). Analyses of the amino acid composition of the C-terminus showed a high content of serine and treonine residues which are potential phosphorylation sites. These characteristic features of the S-layer of B. sphaericus JG-A12 make the strain perspective for bioremediation and nanotechnological applications.
In this work we are presenting the formation of Pd nanoclusters on the cells of B. sphaericus JG-A12 in the presence of H2 as a reducing agent. These nanoclusters are interesting for the development of bionanocatalysts and biosensors. Further, by embedding cells, spores or S-layers using sol-gel techniques bioceramics particles were produced (5, 6). These bioceramics can be used for bioremediation of heavy metal contaminated waters.

References
1. Selenska-Pobell, S. et al. (1999) FEMS Microbiol. Ecol. 29, 59-67
2. Raff, J. (2002) "Wechselwirkungen der Hüllproteine von Bakterien aus Uranabfallhalden mit Schwermetallen" PhD thesis, FZR-Report No. 358.

3. Sleytr, U. et al. (1997) FEMS Microbiol. Rev. 20, 47-97.
4. Merroun M. et al. (2003) FZR-Report No. 364, p. 26-30
5. Raff, J. et al. (2003) Chem. Mater. 15 (1): 240-244.
6. Soltmann et al. (2003) J Sol-Gel Science and Technology 26, 1209-1212.
  • Poster
    Workshop Umwelttechnologie Freiberg 5.-7.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5874
Publ.-Id: 5874


Archaeal and bacterial populations in soil and water samples from the uranium mill tailings Gittersee/Coschütz

Radeva, G.; Flemming, K.; Satschanska, G.; Selenska-Pobell, S.;
Bacterial and archaeal populations in soil and water samples of the uranium mill tailings Gittersee/Coschütz were studied by using the rDNA retrieval applying different sets of PCR amplification primers. Bacterial communities found in both soil and water samples had similar composition as estimated via analyses of the constructed 16S rDNA43F-1404R and 16S rDNA7F-1513R clone libraries. They consisted of proteobacteria (mainly from the gamma-subclass) and of representatives of the Cytophaga/Flavobacterium/Bacteroides (CFB) group. In the soil samples Gram-positive bacteria were found as well. These results are in contrast to those obtained by the analysis of the samples collected from the uranium mining waste pile near the town of Johanngeorgenstadt where members of the alpha proteobacteria and of the Holophaga/Acidobacterium phylum were found to be predominant by using the same 16S rDNA PCR amplification primers (1, 2, 3).
The analysis of the water samples applying the ribosomal intergenic spacer amplification rDNA retrieval using the 16S rDNA968F and 23S rDNA130R PCR primers revealed much higher diversity. In addition to the members of the Proteobacteria and of the CFB, populations of Nitrospira, Verrucomicrobia, Planctomycetales, Actinobacteria and also of several novel bacterial divisions were found (4). This result is due to the primer structures (5).
The identified archaeal populations, in contrast to those of the bacteria, were not very diverse in the studied environment. In the archaea-specific 16S rDNA21F-958R clone libraries constructed for the above mentioned soil and water samples only a few populations of not yet cultured Crenarchaeota were found (6).
Most of the 16S rDNA sequences obtained in this work showed no close phylogenetic affiliation to cultured bacteria or archaea. For this reason, it is difficult to predict the phenotypic properties and the ecological role of the corresponding organisms. However, it is interesting that the most related 16S rDNA sequences found in the Gene Bank were retrieved in environments with geologic and ecological properties similar to those of the uranium wastes, such as gold mine and other acid mine drainage systems (7, 8).
Efforts to culture representatives from some of the most predominant microbial populations are in progress.

References

1. Selenska-Pobell, S. et al. (2002) Bacterial communities in uranium mining waste piles and their interaction with heavy metals, p.455-464; In Uranium in the aquatic environment. Springer-Verlag.
2. Selenska-Pobell, S., et al. (2001) Antonie van Leeuwenhoek 79, 149-161.
3. Geißler, A. (2003) Molekulare Analyse der bakteriellen Diversität in Uranabraumhalden. Diploma Thesis, FZR-Report No. 377
4. Selenska-Pobell, S. (2002) Diversity and activity of bacteria in uranium waste piles, p. 225-253; In, Interactions of Microorganisms with Radionuclides. Elsevier Sciences, Oxford, UK.
5. Derakshani, M., et al. (2001) Appl. Environ. Microbiol. 67: 623-631.
6. Radeva, G. and Selenska-Pobell, S. (2003) FZR-Report No. 373, p. 29
7. Takai, K., et al. (2001) Appl. Env. Microbiol. 67, 5750-5760.
8. Stein, L., et al. (2002) FEMS Microb. Ecol. 42, 431-440.
  • Poster
    Umweltmikobiologie Workshop Freiberg 5.-7.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5873
Publ.-Id: 5873


Bacterial diversity and monitoring of Geobacter sp. in uranium contaminated soils

Geißler, A.; Tzvetkova, T.; Selenska-Pobell, S.;
Bacterial diversity was investigated by using the 16S rDNA retrieval in soil samples collected from a uranium mining waste pile called Haberland situated near the town of Johanngeorgenstadt, Germany, and from one uranium mill tailings in the USA, namely Shiprock, New Mexico. Significant differences were found in the composition of the bacterial communities at the studied sites. Alpha-Proteobacteria and representatives of the Holophaga/Acidobacterium phylum are predominant at the uranium mining waste pile Haberland, whereas the Shiprock uranium mill tailings is mainly occupied by Bacillales, g-Proteobacteria, and Green non-sulfur bacteria. The observed differences in the composition of the bacterial communities in the two studied environments are most probably connected to their different grade of contamination with heavy metals, and also to their different geographic and geologic origin (1).
Representatives of the Geobacter genus were found in both samples studied, but mainly by using Geobacter specific primers. This indicates that the Geobacter populations are probably not predominant in the studied environments. The exact quantification of these populations will be performed by using Real-Time PCR (work in progress). Geobacteracea are involved in reduction of heavy metals (e.g. iron) and radionuclides (e.g. uranium). Because these bacteria can significantly influence the mobility of the mentioned metals (2) their quantification in the uranium wastes is of great importance.

References:
1. Geißler, A. (2003) Molekulare Analyse der bakteriellen Diversität in Uranabraumhalden. Diploma Thesis,
Wissenschaftlich-Technische Berichte des Forschungszentrums Rossendorf FZR-377.

2. Lovley, D. R. et al. (1993) Archives of Microbiology 159: 336-344.
  • Poster
    Workshop Umweltmikrobiologie Freiberg 5.-7.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5872
Publ.-Id: 5872


Investigation of a tin liquid metal ion source

Bischoff, L.; Akhmadaliev, C.; Mair, A. W. R.; Mair, G. L. R.; Ganetsos, T.; Aidinis, C. J.;
A Sn liquid metal ion source was prepared employing a Ni needle to anchor the liquid ion emitter. The main source properties, i.e., the I-V curve, the mass spectra, the energy spread for the main species, as well as the long term source stability were systematically studied. Moreover, a new etching technique for Ni tips has been developed. The mass spectra show a large amount of Sn clusters, apart from the dominant species, Sn+ and Sn++. The source was stable down to 1µA emission current, corresponding to an energy spread for the singly-charged ions of 7 eV. Theoretical arguments strongly suggest that both Sn+ and Sn++ are emitted by direct field-evaporation from the liquid surface.
Keywords: tin liquid metal ion source, Ni emitter assembly needle, mass spectra, energy spread

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Permalink: https://www.hzdr.de/publications/Publ-5871
Publ.-Id: 5871


Azimuthal Dependence of Collective Expansion for Symmetric Heavy-Ion Collisions

Stoicea, G.; Petrovici, M.; Andronic, A.; Herrmann, N.; Alard, J. P.; Barret, V.; Basrak, Z.; Bastid, N.; Caplar, R.; Crochet, P.; Dupieux, P.; Dzelalija, M.; Fodor, Z.; Hildenbrand, K. D.; Hong, B.; Kecskemeti, J.; Kim, Y. J.; Kirejczyk, M.; Korolija, M.; Kotte, R.; Kress, T.; Lebedev, A.; Leifels, Y.; Lopez, X.; Merschmeyer, M.; Neubert, W.; Pelte, D.; Rami, F.; Reisdorf, W.; Schüll, D.; Seres, Z.; Sikora, B.; Sim, K. S.; Simion, V.; Siwek-Wilczynska, K.; Smolyankin, S.; Stockmeier, M.; Wisniewski, K.; Wohlfarth, D.; Yushmanov, I.; Zhilin, A.; Danielewicz, P.;
Detailed studies of the azimuthal dependence of the mean fragment and flow energies in the Au+Au and Xe+CsI systems are reported as a function of incident energy and centrality. Comparisons between data and model calculations show that the flow energy values along different azimuthal directions could be viewed as snapshots of the fireball expansion with different exposure times. For the same number of participating nucleons more transversally elongated participant shapes from the heavier system produce less collective transverse energy. Good agreement with Boltzmann-Uehling-Uhlenbeck calculations is obtained for a soft nuclear equation of state.

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Permalink: https://www.hzdr.de/publications/Publ-5870
Publ.-Id: 5870


The pseudo-Hermiticity of MHD dynamo operators

Günther, U.;
The presentation provides a short introduction to MHD dynamos and to the pseudo-Hermiticity properties of the matrix differential operator of the spherically symmetric α2-dynamo.
In the first part of the lecture, the underlying physics is described starting from a discussion of the homopolar disk dynamo, of field reversals of the Earth's magnetic field and of the dynamo experiments in Riga and Karlsruhe. Furthermore, a sketchy outline of the helicity based meanfield technique for the MHD induction equation is presented and the closing of the dynamo cycle is discussed.
In the second part, attention is paid to the derivation of the matrix differential operator for the spherically symmetric α2-dynamo and its associated quadratic operator pencil. Boundary conditions, pseudo-Hermiticity and Krein-space features are used to heuristically explain the level-crossing properties of the spectrum. Along the lines of [1], the derivation of a constructive no-go theorem for isospectral dynamo configurations is described and interesting open problems are listed.

[1] Günther U. and Stefani F., Isospectrality of spherical MHD dynamo operators: pseudo-Hermiticity and a no-go theorem,
J. Math. Phys. 44, 2003, 3097, math-ph/0208012.

Permalink: https://www.hzdr.de/publications/Publ-5869
Publ.-Id: 5869


Intertwiners of pseudo-Hermitian 2×2-block-operator matrices and a no-go theorem for isospectral MHD dynamo operators

Günther, U.;
Pseudo-Hermiticity as a generalization of usual Hermiticity is a rather common feature of (differential) operators emerging in various physical setups. Examples are Hamiltonians of PT- and CPT-symmetric quantum mechanical systems [1] as well as the operator of the spherically symmetric α²-dynamo [2] in magnetohydrodynamics (MHD). In order to solve the inverse spectral problem for these operators, appropriate uniqueness theorems should be obtained and possibly existing isospectral configurations should be found and classified. As a step toward clarifying the isospectrality problem of dynamo operators, we discuss an intertwining technique for η-pseudo-Hermitian 2×2-block-operator matrices with second-order differential operators as matrix elements. The intertwiners are assumed as first-order matrix differential operators with coefficients which are highly constrained by a system of nonlinear matrix differential equations. We analyze the (hidden) symmetries of this equation system, transforming it into a set of constrained and interlinked matrix Riccati equations. Finally, we test the structure of the spherically symmetric MHD α²-dynamo operator on its compatibility with the considered intertwining ansatz and derive a no-go theorem.

[1] Bender C.M. and Boettcher S., Real spectra in non-Hermitian Hamiltonians having PT symmetry, Phys. Rev. Lett. 80, 1998, 5243, physics/9712001; Znojil M., PT-symmetric harmonic oscillators, Phys. Lett. A259, 1999, 220, quant-ph/9905020; Bender C.M., Brody D.C. and Jones H.F., Complex extension of quantum mechanics, Phys. Rev. Lett. 89, 2002, 270401, quant-ph/0208076.

[2] Günther U. and Stefani F., Isospectrality of spherical MHD dynamo operators: pseudo-Hermiticity and a no-go theorem,
J. Math. Phys. 44, 2003, 3097, math-ph/0208012.
Keywords: MHD, dynamo, discrete symmetry, Krein space, Supersymmetry, operator intertwining technique, matrix Riccati equation
  • Lecture (Conference)
    Fifth International Conference "Symmetry in Nonlinear Mathematical Physics" June 23-29, 2003, Institute of Mathematics, National Academy of Sciences of Ukraine, Kyiv (Kiev), Ukraine
  • Proceedings of the Institute of Mathematics of the National Academy of Sciences of Ukraine 50(2004, 780-787

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Permalink: https://www.hzdr.de/publications/Publ-5868
Publ.-Id: 5868


Riga dynamo experiment and its theoretical background

Gailitis, A.; Lielausis, O.; Platacis, E.; Gerbeth, G.; Stefani, F.;
It is widely believed that almost all magnetic fields in a natural environment are the result of the dynamo process - the field generation in moving nearly homogeneous electro-conducting fluids. This dynamo process occurs in the depths of celestial bodies such as the Earth, most of the planets, the Sun, other stars, and even galaxies.The Riga dynamo experiment is not intended as a model of any particular celestial body. It aims at demonstrating the basic dynamo mechanism - that the intense motion in a large volume of a good electro-conducting liquid creates a magnetic field. In the present paper, the set-up and the main results of this experiment are presented, with some focus on the theoretical interpretation of the data.
  • Physics of Plasmas 11(2004), 2828-2843

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Permalink: https://www.hzdr.de/publications/Publ-5867
Publ.-Id: 5867


Influence of the pipe diameter on the structure of the gas-liquid interface in a vertical two-phase pipe flow

Prasser, H.-M.; Beyer, M.; Böttger, A.; Carl, H.; Lucas, D.; Schaffrath, A.; Schütz, P.; Weiß, F.-P.; Zschau, J.;
Two-phase flow tests in a 194.1 mm diameter vertical pipe (DN200) with an air-water mixture are reported. Close to the upper end of a 9 m tall test section a wire-mesh sensor is installed that delivers instantaneous void fraction distributions over the entire cross section with time resolution of 2500 frames per second. The sensor disposes of 64x64 measuring points, which corresponds to a spatial resolution of 3 mm. Beside an fast flow visualisations, void-fraction profiles and bubble size distributions were obtained. Earlier, similar experiments were carried out in a pipe of 51.2 mm inner diameter (DN50). A comparison of the data from the two different facilities allows to study the scaling effects on void fraction profiles, bubbles size distributions and the flow patterns. In the small pipe, the increase of the air flow rate leads to a transition from bubbly via slug to churn turbulent flow.
The transition to slug flow is accompanied by the appearance of a second peak in the bubble size distribution that corresponds to the class of large Taylor bubbles. A similar qualitative behaviour was found in the large pipe, though the large bubble fraction has a significantly bigger mean diameter at identical superficial velocities, the peak is less tall but wider. Bubbles move more freely than in the small pipe, since the confining action of the pipe walls to the flow is less pronounced, while the large Taylor bubbles occupy almost the entire cross section in case of the small pipe. Furthermore, the bubbles show much more deformations in the large pipe. Shapes of such large bubbles were characterised in three dimensions for the first time. They can rather be complicated and far from the shape of ideal Taylor bubbles. Also the small bubble fraction tends to bigger sizes in the large pipe.

Keywords: two-phase flow, vertical upwards flow, wire-mesh sensor, flow pattern, bubble size
  • Lecture (Conference)
    10th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-10), Seoul, Korea, October 5-9, 2003; conference-CD: A00308
  • Contribution to proceedings
    10th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-10), Seoul, Korea, October 5-9, 2003; conference-CD: A00308

Permalink: https://www.hzdr.de/publications/Publ-5866
Publ.-Id: 5866


An in-depth investigation into the temperature dependence of the mass spectra of the beam produced by a Au82Si18 liquid metal field emitter

Mair, G. L. R.; Bischoff, L.; Londos, C. A.; Ganetsos, T.; Akhmadaliev, C.; Aidinis, C. J.;
The mass spectra of the beam emitted by a Au82Si18 eutectic molten metal ion source are investigated in detail, as a function of emitter temperature. At the conclusion of the work it emerges that while Au+, Si+ and Si++ are the result of direct field-evaporation from the liquid surface, Au++ forms by the post-ionisation of Au+. Cluster ions are most probably the product of droplet break-up.
Keywords: liquid metal ion sources, field ion emission, temperature dependence
  • Applied Physics A81 (2005) 385 - 388

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Permalink: https://www.hzdr.de/publications/Publ-5865
Publ.-Id: 5865


Rayleigh-Benard instability in a cylinder under influence of rotating and steady magnetic fields

Grants, I.; Gerbeth, G.;
This paper considers numerically the linear and non-linear instability of a liquid metal in a vertical cylinder with hot bottom, cold top and adiabatic side walls subject to superimposed rotating and steady axisymmetric magnetic fields. In the non-linear case, a threshold is determined for the global stability against finite size perturbations. It is shown that a proper magnetic field combination stabilizes the system much better than any of the fields separately.

  • Physics of Fluids, 162004(2004)6, 2088-2096

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Permalink: https://www.hzdr.de/publications/Publ-5863
Publ.-Id: 5863


Evidence for a new type of shears mechanism in 106Cd

Simons, A. J.; Wadsworth, R.; Jenkins, D. G.; Clark, R. M.; Cromaz, M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Lane, G. J.; Lee, I. Y.; Macchiavelli, A. O.; Stephens, F. S.; Svensson, C. E.; Vetter, K.; Ward, D.; Frauendorf, S.;
Lifetimes of states in the lowest lying positive parity band in 106Cd have been measured using the Doppler shift attenuation method. The deduced D(E2) transition rates show a marked decrease with increasing spin. Cranking and semiclassical model calculation suggest that the structure has the character of a shears-type band resulting from the coupling of g9/2 proton holes to aligned pairs of h11/2and g7/2 neutron particles. This is the first clear evidence for the phenomenon of "antimagnetic" rotation in nuclei.
  • Phys. Rev. Letters, Volume 91, No. 16, 162501

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Permalink: https://www.hzdr.de/publications/Publ-5861
Publ.-Id: 5861


A composite chiral pair of rotational bands in the odd-A nucleus 135Nd

Zhu, S.; Garg, U.; Nayak, B. K.; Ghugre, S. S.; Pattabiraman, N.; Fossan, D. B.; Koike, D. B.; Starosta, K.; Vaman, C.; Janssens, R. V. F.; Chakrawarthy, R. S.; Whitehead, M.; Macchiavelli, A. O.; Frauendorf, S.;
High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd reaction at a 30Si bombarding energy of 133 MeV. Two dI=1 bands with close excitation energies and the same parity were observed. These bands are directly linked by dI=1 and dI=2 transitions. The chiral nature of these two bands is confirmed by comparison with three-dimensional tilted axis cranking calculations. This is the first observation of a three-quasiparticle chiral structure and establishes the primary geometric nature of this phenomenon.
  • Phys. Rev. Letters, Volume 91, No. 13

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Permalink: https://www.hzdr.de/publications/Publ-5860
Publ.-Id: 5860


Inverse problems in magnetohydrodynamics: theoretical and experimental aspects

Stefani, F.; Gerbeth, G.; Günther, U.; Gundrum, T.; Xu, M.;
The interaction of magnetic fields with moving electrically conducting fluids is the subject of magnetohydrodynamics. There is a vast area of applications, e.g. in metal casting and crystal growth, where magnetic fields are used to act on the melt flow in order to improve the quality of the products. On the other hand, the moving fluid can also influence externally applied magnetic fields, and for large magnetic Reynolds numbers it can even yield self-excitation of a magnetic field. This effect, called homogeneous dynamo effect, is at the root of magnetic field generation in planets, stars, and galaxies.
We focus on several inverse problems connected with the determination of velocities or velocity related quantities from magnetic field information that is measurable outside the fluid region. The underlying theory is presented in the framework of the integral equation approach to dynamos in finite domains, which can be cast into a linear inverse problem in case that the magnetic Reynolds number of the flow is not too large.
In this case it is necessary to apply external magnetic fields and to measure the flow induced electromagnetic fields. Two possibilities are considered: one can apply one magnetic field and measure the external induced magnetic field and the electric potential at the fluid boundary, or one can apply two different magnetic fields and measure the corresponding two sets of external induced magnetic fields.This latter contactless method is especially interesting for applications with hot and aggressive fluids or for facilities where the fluid boundary is not accessible for technological reasons. We consider the uniqueness problems of both methods finding that the rough topology of the flow can be determined from the measured data but that the depth dependence of the velocity must be inferred by regularization methods. We present first results of an experiment with a flow of InGaSn exposed to an externally magnetic field pointing subsequently in two different directions.
The linear character of the inverse MHD problem is lost when it comes to dynamos which work exclusively at large magnetic Reynolds numbers. Inverse dynamo problems are well known in geophysics and solar physics where information on the velocity structure is to be drawn from magnetic field data. They have acquired new relevance recently with the liquid sodium experiments in Riga and Karlsruhe. In connections with those experiment there are quite new inverse, design, and optimization problems. We show that even the simplest inverse spectral dynamo problems for very symmetric dynamos are far from trivial, compared to similar problems in quantum mechanics. We present examples where evolution strategies can successfully be employed to solve particular inverse
dynamo problems.
  • Lecture (Conference)
    Inverse problems, design and optimization symposium, 17.-19.03.2004, Rio de Janeiro, Brazil
  • Contribution to proceedings
    Inverse problems, design and optimization symposium, 17.-19.03.2004, Rio de Janeiro, Brazil
    Proceedings of the Inverse problems, design and optimization (IPDO-2004), Vol. II, Rio de Janeiro: E-papers Publishing House Ltd, 85-7650-030-2, 151-158
  • Inverse Problems in Science and Engineering 14(2006)4, 411-422
    DOI: 10.1080/17415970600573791

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Permalink: https://www.hzdr.de/publications/Publ-5859
Publ.-Id: 5859


Förderprogramm Immissionsschutz - Bilanz 1996

Enkelmann, W.; Maletti, R.;
  • Contribution to external collection
    Materialien zur Luftreinhaltung, Sächsisches Staatsministerium für Umwelt und Landesentwicklung, 1 (1997) Juni 1997,

Permalink: https://www.hzdr.de/publications/Publ-5858
Publ.-Id: 5858


The LSO/APD array as a possible detector for in-beam PET in hadron therapy.

Kapusta, M.; Crespo, P.; Wolski, D.; Heidel, K.; Heinrich, L.; Hutsch, J.; Pawelke, J.; Sobiella, M.; Trzcinska, A.; Moszynski, M.; Enghardt, W.;
We have studied the performance of finger like LSO:Ce (LSO) crystals coupled one by one to pixels of avalanche photodiode detector (APD) arrays during their operation in coincidence at 12C ion beams of parameters being typical for tumor irradiations. In a first step of these experiments the parameters of the detectors and the signal processing setup has been characterized off-beam, i.e. by means of beta+ radioactive sources (22Na, 68Ge). Afterwards, the apparatus was installed at the medical beam line of the heavy ion synchrotron (SIS) of the Gesellschaft für Schwerionenforschung (GSI) at Darmstadt, Germany. Here, the beta+ activity produced by nuclear fragmentation reactions of 12C 200.3 AMeV heavy ion beams with polymerized methyl methacrylate (PMMA) phantoms were measured. Furthermore, a 68Ge source was included into the in-beam experiment, in order to check the stability of the setup and to compare energy and time resolution before, during and after phantom irradiations. Additionally, it could be demonstrated by means of high resolution gamma-ray spectroscopy that LSO is not activated by the light projectile fragments escaping the patients downbeam during therapeutic irradiations. The experimental results indicate, that LSO scintillator is a suitable material for in-beam PET and, furthermore, the LSO/APD array is a feasible detector concept for in-beam monitoring of the dose application by means of PET.
  • Lecture (Conference)
    IEEE Nuclear Science Symposium and Medical Imaging Conference, Portland, USA, Oct. 19-25, 2003
  • IEEE Transactions on Nuclear Science 51(2004)4, 1389-1394
    DOI: 10.1109/TNS.2004.832318
  • Contribution to proceedings
    IEEE Nuclear Science Symposium and Medical Imaging Conference, Portland, USA, Oct. 19-25, 2003

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Publ.-Id: 5857


Interactions of Carbon in a Repository Environment

Kienzler, B.; Metz, V.; Kelm, M.; Nebelung, C.; Baraniak, L.;
Release and migration of 14C cannot be treated independently from the bulk of inorganic and organic carbon waste components in a repository. 14C is mainly produced by (n,p) reaction from 14N. Important sources of 14C is zircalloy (according ASTM standard Nmax: 65 ppm), the fuel (N contamination and ternary fission) as well as some other reactor components. In Germany, spent fuel elements from High Temperature Reactors (HTR) will contribute also to the total 14C load of a radioactive waste disposal. Additionally, organic materials containing 14C markers, metals containing 14C as carbides and other low level waste forms containing 14C in carbonates or in ashes have to be taken into account.
14C in graphite from spent HTR fuel elements is nearly immobile. Other waste forms may release 14C in a large variety of inorganic and organic species. Reactions of carbides with water/brine produce methane or acetylene gas. By microbial reactions, organic 14C can be transformed into gases 14CO2 and 14CH4.
Interactions of HTR fuel with brines were investigated at FZJ. At FZK-INE and FZR, various experimental and theoretical investigations have been performed in order to quantify the release of this isotope.
Limiting the concentrations of (bi-)carbonates in solution results in a low actinide solubility, especially at high pH. For this reason, at WIPP, a Mg bearing backfill material (periclase, MgO) is added to the wastes in order to keep the concentration of HCO3-/CO32- at a minimum. For the Asse salt mine, a backfill material was proposed by FZK-INE. This material consists mainly of brucite (Mg(OH)2(s)) and sorel phases (Mg2x(OH)(2x-1)Cl·4H2O(s)). Various experimental and modelling studies were carried out to determine the stability of the Mg(OH)2(s)-based material in the relevant brines, formation of the reaction products, and the effect of the material on actinide solubility in the case of carbonate-input to the brines. Experimental findings are in agreement with the modeling predictions. By precipitating carbonates from solution, an isotopic exchange effect will occur, which will control the 14C concentration in solution.
For the ERAM system, sorption of 14CO32- onto salt concrete, sorel concrete and other backfill materials was investigated. For all materials under investigation, sorption showed distinct time dependences. The weakest sorption was observed in case of salt concrete. Sorel phases reduced the 14C concentration by more than 2 orders of magnitude during a 0.5 yr. period. Since the studied backfill materials contained to some extent solid carbonates, the retention process can be explained by isotopic exchange.
Sorption of methane (CH4) onto the backfill materials was investigated by contacting a brine/backfill slurry with the gas. The tests were performed by monitoring the concentration of gaseous CH4 in a mixture with a noble gas (Ar) which does not react with slurry components. The analysis of experimental results shows that the ratio of CH4/Ar remains constant within a deviation of 5%. Consequently, the total methane sorption onto the studied backfill materials remains below 0.2 mmol CH4/kg solid material.
Keywords: 14C,carbonate, methane, Asse, ERAM, migration, Release, carbon waste, HTR, fuel, brines, brucite, sorel phases, sorption, retention process
  • Lecture (Conference)
    14C Workshop NAGRA, Wettingen27-28.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5856
Publ.-Id: 5856


Particle identification at HADES

Kugler, A.; Agakichiev, H.; Agodi, C.; Alvarez-Pardo, M.; Alvarez-Pol, H.; Badura, E.; Balanda, A.; Ballester, F.; Bassi, A.; Bassini, R.; Bellia, G.; Bertini, D.; Bielcik, J.; Böhmer, M.; Boiano, C.; Bokemeyer, H.; Boyard, J. L.; Brambilla, S.; Braun-Munzinger, P.; Chernenko, S.; Coniglione, R.; Dahlinger, M.; Daues, H.; Diaz, R.; Dohrmann, F.; Duran, I.; Eberl, T.; Fabbietti, L.; Fateev, O.; Fernandez, C.; Finocchiaro, P.; Friese, J.; Fröhlich, I.; Fuentes, B.; Garzon, J. A.; Genolini, B.; Gernhäuser, R.; Golubeva, M.; Gonzales, D.; Goringer, H.; Grosse, E.; Guber, F.; Hehner, J.; Hennino, T.; Hlavac, S.; Hoffmann, J.; Holzmann, R.; Homolka, J.; Ierusalimov, A.; Iori, I.; Jaskula, M.; Kämpfer, B.; Kanaki, K.; Karavicheva, T.; Kirschner, D.; Kidon, L.; Kienle, P.; Koenig, I.; Koenig, W.; Körner, H.-J.; Kolb, B. W.; Kopf, U.; Kotte, R.; Kühn, W.; Kurtukian, T.; Krücken, R.; Kulessa, R.; Kurepin, A.; Lehnert, J.; Lins, E.; Magestro, D.; Maier-Komor, P.; Maiolino, C.; Markert, J.; Metag, V.; Mousa, J.; Münch, M.; Naumann, L.; Nekhaev, A.; Niebur, W.; Ott, W.; Novotny, R.; Otwinowski, J.; Panebratsev, Y.; Pechenov, V.; Petri, M.; Piattelli, P.; Pietraszko, J.; Pleskac, R.; Ploskon, M.; Pryzgoda, W.; Rabin, N.; Ramstein, B.; Reshetin, A.; Ritman, J.; Rosier, P.; Roy-Stephan, M.; Rustamov, A.; Sabin, J.; Sadovski, A.; Sailer, B.; Salabura, P.; Sanchez, M.; Sapienza, P.; Senger, P.; Schroeder, C.; Shileev, K.; Shishov, P.; Simon, R.; Smoliankin, V.; Smykov, L.; Spataro, S.; Stelzer, H.; Ströbele, H.; Stroth, J.; Sturm, C.; Sudol, M.; Taranenko, A.; Tlusty, P.; Toia, A.; Traxler, M.; Tsertos, H.; Turzo, I.; Vassiliev, D.; Vazquez, A.; Wagner, V.; Walus, W.; Winkler, S.; Wisniowski, M.; Wojcik, T.; Wüstenfeld, J.; Yahlali, N.; Zanevsky, Y.; Zeitelhack, K.; Zovinec, D.; Zumbruch, P.; Keywords: di-electron electron pair HADES hadron heavy-ion collisions Particle identification

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Publ.-Id: 5855


Dose quantification from in-beam PET.

Enghardt, W.; Crespo, P.; Fiedler, F.; Parodi, K.; Pawelke, J.; Pönisch, F.;
  • Lecture (Conference)
    Extended Abstracts of the 9th Workshop on Heavy Charged Particles in Biology and Medicine, Lyon, France, Oct. 2-5 (2003) 45-46
  • Contribution to proceedings
    Extended Abstracts of the 9th Workshop on Heavy Charged Particles in Biology and Medicine, Lyon, France, Oct. 2-5 (2003) 45-46

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Publ.-Id: 5854


Radioactive beams.

Kanazawa, M.; Kitagawa, A.; Kanai, T.; Murakami, T.; Noda, K.; Suda, M.; Tomitani, T.; Torikoshi, M.; Urakabe, E.; Sato, S.; Mizuno, H.; Pawelke, J.; Hanawa, K.; Iseki, Y.; Sato, K.;
no abstract
  • Lecture (Conference)
    Extended Abstracts of the 9th Workshop on Heavy Charged Particles in Biology and Medicine, Lyon, France, Oct. 2-5 (2003) 55-57
  • Contribution to proceedings
    Extended Abstracts of the 9th Workshop on Heavy Charged Particles in Biology and Medicine, Lyon, France, Oct. 2-5 (2003) 55-57

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Publ.-Id: 5853


Influence of Humic Acids on the Migration of Uranium (IV)/(VI) in Quartz Sand

Mibus, J.; Sachs, S.; Nebelung, C.; Bernhard, G.;
This study investigates the migration behavior of U(IV) and U(VI) in the system humic acid / uranium / quartz sand by means of column experiments. Humic acid exhibits a significant influence on the transport of U(IV) and U(VI). In case of U(VI) a clear mobilizing effect was observed. There are strong indications for a similar influence of humic acid on U(IV) transport. Both redox species of uranium differ slightly in their migration behavior in presence of humic acid. This is mainly reflected in a disagreement of their total recoveries. The observed difference amounts to approximately 25 %.
Keywords: Actinides, Uranium, U(IV), U(VI), Humic Acids, Quartz Sand, Migration, Sorption, Column Experiments, Reducing Conditions
  • Lecture (Conference)
    11th International Symposium on Water Rock Interaction WRI-11, 27.06.-02.07.2004, Saratoga Springs, NY, United States
  • Contribution to proceedings
    11th International Symposium on Water-Rock Interaction WRI-11, 27.06.-02.07.2004, Saratoga Springs , NY, United States
    Proceedings, 691-695

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Publ.-Id: 5852


Atomic computer simulations of defect migration in 3C and 4H-SiC

Gao, F.; Weber, W. J.; Posselt, M.; Belko, V.;
Knowledge of the migration of intrinsic point defects is crucial to understand defect recovery, various annealing stages and microstructural evolution after irradiation or ion implantation. Molecular dynamics (MD) and the nudged-elastic band method have been applied to investigate long-range migration of point defects in SiC over the temperature range from 0.36 to 0.95 Tm , and the defect diffusion coefficient, activation energy and defect correlation factor have been determined. The results show that the activation energies for C and Si interstitials in 3C-SiC are about 0.74 and 1.53 eV, respectively, while it is about 0.77 eV for a C interstitial in 4H-SiC. The minima energy paths reveal that the activation energies for C and Si vacancies are about 4.1 and 2.35 eV, respectively. Finally, the results are discussed and compared with experimental observations and available ab initio data.
Keywords: defects in semiconductors, SiC, computer simulation
  • Lecture (Conference)
    10th Int. Conf. on Silicon Carbide and Related Materials 2003 (ICSCRM 2003), Lyon, France, October 5 - 10, 2003

Permalink: https://www.hzdr.de/publications/Publ-5851
Publ.-Id: 5851


Influence of polytypism on properties of intrinsic defects in SiC

Posselt, M.; Gao, F.; Weber, W. J.; Belko, V.;
Symmetry considerations and classical-potential computer simulations are employed to perform a comparative study of properties of intrinsic defects in 3C- and 4H-SiC. Investigations of the polytype structure reveal that the number of non-equivalent point defects in 4H-SiC should be significantly higher than in 3C-SiC. Most of the potential defects are found to be stable. A considerable difference between 3C- and 4H-SiC exists for some dumbbells with a complex and anisotropic structure. This is due to the important role of lattice deformations beyond the first neighbor shell and the fact that the spatial distribution of these deformations is strongly dependent on the polytype. The interstitials between hexagonal and trigonal rings are characteristic for 4H and other hexagonal polytypes. They do not exist in 3C-SiC. In the case of more compact and isotropic defects, such as vacancies, anitisites, hexagonal interstitials and many dumbbells, the influence of polytypism is small. The properties of tetrahedral interstitials in 3C- and 4H-SiC are very similar since in both polytypes their first, second and third neighbor shells are equal. Besides the elementary defects, the structure and energetics of defect clusters is investigated.
Keywords: defects in semiconductors, SiC, computer simulation
  • Lecture (Conference)
    10th Int. Conf. on Silicon Carbide and Related Materials 2003 (ICSCRM 2003), Lyon, France, October 5 - 10, 2003

Permalink: https://www.hzdr.de/publications/Publ-5850
Publ.-Id: 5850


Tribological properties of ternary BCN films with controlled composition and bonding structure

Caretti, I.; Jiménez, I.; Gago, R.; Abendroth, B.; Albella, J. M.;
In this work we study the mechanical and tribological properties (hardness, elastic modulus, friction and wear) of BCN coatings with controlled composition and structure. The influence of the carbon content in films with BCxN stoichiometry is discussed in connection with the bonding structure, and compared with the mechanical and tribological properties of reference compounds. Since ternary BCN compounds can exhibit a variety of compositions and bonding structures, the knowledge of these parameters is a pre-requisite to study any physical property of BCN coatings. Boron carbonitride (BCN) films were deposited at different temperatures using simultaneous evaporation from separated boron and carbon sources, assisted by different mixtures of Nitrogen and Argon ions from a Kauffman ion gun. In this way, we obtained films with selected composition, as verified with Energy Dispersive X-ray (EDX) spectroscopy, X-ray Absorption Near Edge Spectroscopy (XANES) and Elastic Recoil Detection Analysis (ERDA). The bonding structure of the coatings was determined by combining XANES with vibrational spectroscopies (infrared and Raman). Finally, the mechanical and tribogical characterization was performed with nanoindentation and pin-on-disk techniques, respectively.
Keywords: BCN, Ion assisted deposition, XANES, pin on disk
  • Poster
    14th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide (Diamond 2003), 07-12 September 2003, Salzburg (Austria)
  • Diamond and Related Materials 13(2004), 1532-1537

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Publ.-Id: 5849


Multilayer porous silicon structures for optical devices

Torres-Costa, V.; Martín-Palma, R. J.; Gago-Fernández, R.; Vinnichenko, M.; Martínez-Duart, J. M.;
Porous silicon (PS) has a great potential in optical applications due to its tuneable refractive index. In particular, multilayer structures consisting on PS layers with different refractive indexes can be used as interference filters. Due to the characteristics of PS and its production process, many types of interence filters can be produced: Bragg reflectors, monochromatic filters for light emitting devices (which can also be based on PS), microcavities for biosensing applications, Fabry-Pérot resonators, photonic crystals, etc.

In the present work the optical properties of porous silicon single layers and multilayer structures have been studied. PS is formed by the electrochemical etch of monocrystalline silicon wafers. Since PS can be modelled as an homogeneous mixture of silicon and air (and, eventually, silicon dioxide), its refractive index varies depending on the air content of the porous structure, according to the effective medium theories (EMTs). The electrochemical process gives a perfect control over the porosity –and hence, over the index of refraction- and thickness of the porous silicon layer, since both parameters are highly sensitive to the formation conditions, mainly current density and etching time. In addition, when the current density applied is periodically varied, a multilayer structure is formed. By simply adjusting the refractive index and thickness of each individual layer we can obtain a stack of porous silicon layers with the desired optical properties, resulting in an interference filter of predetermined band width.

The optical characterization has been carried out by spectrophotometric and spectroscopic ellipsommetry measurements. In addition, compositional analysis has been performed by means of Ion Beam Analysis (IBA) techniques, with special interest devoted to oxygen and hydrogen, in order to correlate the optical parameters and the chemical composition. Finally, multilayers structures have been produced and their operation has been checked.
  • Lecture (Conference)
    European Congress on Advanced Materials and Processes (EUROMAT 2003), 1-5 September 2003, Lausanne (Switzerland)

Permalink: https://www.hzdr.de/publications/Publ-5848
Publ.-Id: 5848


Surface patterning by low-energy ion irradiation

Gago, R.; Vázquez, L.; Cuerno, R.; Albella, J. M.; Facsko, S.; Moeller, W.;
The modification of the surface morphology by means of low-energy (0.1-10 keV) ion irradiation is a fascinating process that has been devoted to intense study during the last decades. The first implications of this process were considered due to secondary effects derived from the ion-modified roughness, such as secondary ion emission (SIMS). However, the ability to produce regular and self-organized patternings in the nanoscale range, related to the typical size of the ion collision cascade, has recently attracted the interest on this process due to its potential applications in Nanotechnology. Depending on the ion incidence angle, different morphologies can be induced on the surface, namely ripples and dots [1]. The universality of the process has been demonstrated by the production of patterns either on metals (Ag, Cu), semimetals (graphite), semiconductors (GaSb, GaAs, InP, Si, Ge) and insulators (glass, SiO2). The mechanisms leading to the formation of these patternings have also attracted intense theoretical studies [3]. The successful approach considers continuum equations where an instability results from the interplay between roughening, due to the dependence of the ion sputtering yield on the local surface curvature, and smoothing processes (thermal and ion-induced). Finally, the applications of these nanostructures are still to be exploited. Several applications as optical filters, quantum wires, quantum dots, magnetic nanostructures, and templates have been addressed. In addition, the latter application has been already realized, transferring the pattern from Si surfaces to polymeric and metallic films [4]. Complementary, the possible functionalization of the surface for biological or catalytic processes can also open a wide range of potential applications.

[1] Navez et al. C.R. Acad. Sci, Paris 254 (1962) 240; Facsko et al. Science 285 (1999) 1551.
[2] Gago et al. Appl. Phys. Lett. 78 (2001) 3316; Gago et al. Nanothecnology 13 (2002) 304.
[3] Bradley et al. J. Vac. Sci. Technol. A 6 (1988) 2390; Cuerno et al. Phy. Rev. Lett. 74 (1995) 4746.
[4] Azzaroni et al. Appl. Phys. Lett. 82 (2003) 457; Azzaroni et al. Nanotechnology (submitted)
  • Lecture (Conference)
    International Summer School on Vacuum, Electron and Ion Technologies (VEIT 2003), 15-19 September, Varna (Bulgaria)

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Publ.-Id: 5847


Surface Nanopatterning of Metal Thin Films by Physical Vapor Deposition onto Surface-Modified Silicon Nanodots

Azzaroni, O.; Fonticelli, M.; Schilardi, P. L.; Caretti, I.; Gago, R.; Vázquez, L.; Salvarezza, R. C.;
One of the most active research topics within the nanoscience and nanotechnology fields are those related to large-scale fabrication, in an accurate manner, of nanostructured metal thin films [1]. This interest is due to their potential applications for different technological purposes such as electrocatalysis [2] and optical devices [3]. In order to obtain these nanostructured films different techniques, such as ion sandblasting [4] or nanotransfer printing [5], have been developed. In this work we present results on the largescale preparation of nanostructured metal thin films from surface-modified silicon nanodots templates [6]. The nanopatterning process is based on the deposition of a copper thin film (approximately 300nm thick) by physical vapor deposition on nanostructured silicon substrates [7], which were previously surface-modified with an octadecyltrichlorosilane (OTS) self-assembled monolayer in order to promote an easy metal film detachment after deposition. Once the 300 nm thick film has been deposited, a thick (10 mm approximately) film of copper is electrodeposited onto it to improve the mechanical properties of the physically-deposited nanostructured thin film. Thanks to the very low adhesion of OTS layer to the metal film the latter is easily mechanically detached from the template, leading to a surface nanostructure corresponding to the negative replica of the original nanopatterned silicon template. This metal nanopatterning strategy shows potential applications for accurate large-scale fabrication of nanostructured metal thin films.

[1] G.L. Egan, J.-S. Yu, C.H. Kimm, S.J. Lee, R.E. Schaak, T.E. Mallouk, Adv.Mater. 12,1040 (2000)
[2] G.S. Attard, et al., Science, 278, 838 (1997)
[3] M.B. Sobnack, et al., Phys.Rev.Lett. 80, 5667 (1998)
[4] S. Rusponi, G. Constantini, F. Buatier de Mongeot, C. Borago, U. Valvusa, Appl. Phys. Lett. 75, 3318 (1999).
[5] Y.-L. Loo, et al., J.Am.Chem.Soc. 124, 7654 (2002).
[6] O. Azzaroni, P.L. Schilardi, R.C. Salvarezza, R. Gago, L. Vázquez, Appl. Phys. Lett. 82, 457 (2003).
[7] R. Gago, L. Vázquez, R. Cuerno, M. Varela, C. Ballesteros, J.M. Albella, Appl.Phys.Lett. 178, 3316 (2001).
  • Poster
    Trends in Nanotechnology (TNT2003), 15-19 September 2003, Salamanca (Spain)

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Publ.-Id: 5846


Untersuchung der Metabolisierung von Neurotensin(8-13) mit 99mTc- und 18F-Markierung

Pawelke, B.; Bergmann, R.; Künstler, J.-U.; Kretzschmar, M.; Wittrisch, H.; Johannsen, B.;
  • Poster
    41. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, Essen, 02.-05.04.2003
  • Abstract in refereed journal
    41. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, Essen, 02.-05.04.2003 Nuklearmedizin (2003) 42: A94

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Publ.-Id: 5845


Spectroscopic ellipsometry investigation of amorphous carbon films with different sp3 content: relation with protein adsorption

Vinnichenko, M.; Gago, R.; Huang, N.; Leng, Y. X.; Sun, H.; Kreissig, U.; Kulish, M. P.; Maitz, M.;
The albumin adsorption on non-hydrogenated amorphous carbon films with different diamond-like character (i.e. sp3 content) is addressed. The films were produced by ion beam assisted deposition and by filtered cathodic vacuum arc deposition to obtain a wide range of sp3 contents. A combination of the spectroscopic ellipsometry, Raman spectroscopy and elastic recoil detection analysis was used for characterization of the films. It is shown that an increase of the deposition temperature leads to a decrease of the film band gap, density and a shift of the Raman G-band position. The wettability of the film is not influenced by its sp3 content. Albumin adsorption on the surface depends more on its wetting behavior than on the sp3 content. In addition, Ar ion treatment of the layers can be used to reduce the amount of adsorbed proteins.
Keywords: spectroscopic ellipsometry; Raman scattering; ion bombardment; coatings

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Publ.-Id: 5844


Biodistribution and Catabolism Studies of 18F-labeled Amino Acid and Peptide Derivatives

Pawelke, B.; Bergmann, R.; Helling, R.; Wittrisch, H.; Wüst, F.; Johannsen, B.;
  • Poster
    6. Deutsches Peptidsymposium, Berlin, 23.-26.03.2003

Permalink: https://www.hzdr.de/publications/Publ-5843
Publ.-Id: 5843


Diagnostik von Ein- und Mehrphasenströmungen mit Leitfähigkeits-Gittersensoren

Hampel, U.; Zschau, J.; Prasser, H.-M.;
Leitfähigkeits-Gittersensoren ermöglichen die Untersuchung von Strömungen mit und ohne Gasanteil (Ein- und Zweiphasenströmungen) mit hoher räumlicher und zeitlicher Auflösung. Sie können damit für viele strömungsdiagnostische Probleme eingesetzt werden. Der Beitrag gibt einen Überblick über das Funktionsprinzip, die Gewinnung physikalischer Strömungsparameter aus den elektrischen Messsignalen sowie über Anwendungsgebiete solcher Sensoren.
Keywords: Leitfähigkeitsmessung, Gittersensor, Strömungsdiagnostik
  • Contribution to proceedings
    Proceedings 6. Dresdner Sensor-Symposium - Sensoren für zukünftige Hochtechnologien und Neuentwicklungen für die Verfahrenstechnik, Band 20, G. Gerlach Hrsg., pp. 33-36, w.e.b. Universitätsverlag, 2003

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Publ.-Id: 5842


Complexation of uranium(VI) with glycerol 1-phosphate

Koban, A.; Bernhard, G.;
The complex formation of uranium(VI) with glycerol 1-phosphate was determined by potentiometric titration, UV-vis and TRLFS spectroscopy. Three complexes were found by potentiometry in the pH range 3 - 8, and the stability constants were calculated for I = 0.1 M: 1 : 1 complex UO2(C3H7O3PO3) (log beta11 = 6.23 ± 0.09); 1 : 2 complex UO2(C3H7O3PO3)22- (log beta12 = 10.22 ± 0.13); 2 : 3 complex (UO2)2(C3H7O3PO3)32- (log beta23 = 20.28 ± 0.03). The UV-vis spectra at pH 2 to 4 show an increase of the absorption intensity with increasing ligand concentration, connected with a red shift of the main absorption bands. The three complexes could be isolated by deconvolution of the measured spectra and the stability constants were determined (at I = 0.5 M) to be: log beta11 = 6.15 ± 0.20, log beta12 = 10.38 ± 0.39, and log beta23 = 19.34 ± 0.65. The TRLFS spectra at pH = 4 show also an increase of the fluorescence intensity connected with a red shift of the emission spectra. But contrary to the both above mentioned methods only the 1 : 1 complex UO2(C3H7O3PO3) could be detected under the specific experimental conditions. The main fluorescence emission bands and the lifetime of this complex were determined. The complex stability constant at I = 0.1 M was calculated to be log beta11 = 6.15 ± 0.05.
Keywords: Uranium; glycerol phosphate; complex formation; potentiometric titration; UV-vis; TRLFS

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Publ.-Id: 5841


Uran(VI) complexes with sugar phosphates in aqueous solution

Koban, A.; Geipel, G.; Roßberg, A.; Bernhard, G.;
The complex formation in the aqueous systems of uran(VI) with glucose 6-phosphate (G6P) and fructose 6-phosphate (F6P), respectively, were studied by means of potentiometric titration, TRLFS, and EXAFS. In each case two complexes with a metal-to-ligand ratio of 1 : 1 and 1 : 2 could be observed. Complex stability constants were determined by potentiometric titration for both complexes to be log beta11(G6P) = 5.89 ± 0.40, log beta12(G6P) = 9.45 ± 0.08, log beta11(F6P) = 5.72 ± 0.21, and log beta12(F6P) = 9.54 ± 0.09. By TRLFS stability constants could be calculated under the specific experimental conditions only for the 1 : 1 complexes (log beta11(G6P) = 6.35 ± 0.28, and log beta11(F6P) = 5.66 ± 0.17).
The TRLFS measurements resulted in that the UO2G6P complex shows no fluorescence properties. For this system only a decrease of the fluorescence intensity with increasing ligand concentration could be observed. For the uranyl fructose 6-phosphate system a red shift of the fluorescence emission bands of about 8 to 9 nm compared to the free uranyl ion was observed. The fluorescence emission wavelengths of the UO2F6P complex were determined to be 483, 496, 518, 542, and 567 nm, and the lifetime of this complex is 0.13 ± 0.05 µs.
Uranium LIII-edge EXAFS measurements at different pH values yielded a shortened U - Oeq bond distance (2.31 ± 0.02 to 2.37 ± 0.02 Angström) compared to the UO22+(H2O)5 ion (2.40 ± 0.02 Angström) due to a monodentate coordination via the oxygen atoms of the phosphate group.
Keywords: Uranium; sugar phosphate; complex formation; TRLFS; EXAFS; potentiometric titration

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Permalink: https://www.hzdr.de/publications/Publ-5840
Publ.-Id: 5840


Positron Emission Tomography Imaging of the Serotonin Transporter in the Pig Brain Using [11C](+)-McN5652 and S-([18F]fluoromethyl)-(+)-McN5652

Brust, P.; Zessin, J.; Kuwabara, H.; Pawelke, B.; Kretzschmar, M.; Hinz, R.; Bergman, J.; Eskola, O.; Solin, O.; Steinbach, J.; Johannsen, B.;
S-([18F]fluoromethyl)-(+)-McN5652 ([18F](+)-FMe-McN5652) has recently been synthesized as a new potential radiotracer for positron emission tomography (PET) imaging of the 5-HT transporter. It is an analog of [11C](+)-McN5652, which has been used in clinical PET studies for 5-HT transporter imaging. This article describes the comparison of these two radiotracers in pigs with respect to their in vivo binding characteristics. PET images revealed that the highest accumulation of both radiotracers was found in the ventral midbrain, thalamus, olfactory lobe, and pons which is consistent with the known density of 5-HT transporters. The specific binding was determined by subtracting the values of the inactive (-) enantiomers or of the occipital cortex from those obtained with [11C](+)-McN5652 or [18F](+)-FMe-McN5652 in the time period between 75 and 115 min after radiotracer injection. The specific binding of the 18F-labeled derivative was about 40 % higher than that of the 11C-labeled derivative. A strong inhibition of the specific binding was observed for both radiotracers after pre-treatment with the selective 5-HT uptake inhibitor citalopram. [18F](+)-FMe-McN5652 showed faster kinetics than [11C](+)-McN5652. It reached the binding equilibrium during a study length of 120 min, which was not the case for [11C](+)-McN5652. It is concluded that [18F](+)-FMe-McN5652 is suitable for 5-HT transporter imaging with PET.
Keywords: serotonin transporter; receptor imaging; positron emission tomography; porcine brain; [18F](+)-FMe-McN5652; citalopram
  • Synapse (2003) 47: 143-151

Permalink: https://www.hzdr.de/publications/Publ-5839
Publ.-Id: 5839


Nuclear stopping from 0.09A GeV to 1.93A GeV and its correlation to flow

Reisdorf, W.; Andronic, A.; Gobbi, A.; Hartmann, O. N.; Herrmann, N.; Hildenbrand, K. D.; Kim, Y. J.; Kirejczyk, M.; Koczon, P.; Kress, T.; Leifels, Y.; Schüttauf, A.; Tyminski, Z.; Xiao, Z. G.; Alard, J. P.; Barret, V.; Basrak, Z.; Bastid, N.; Benabderrahmane, M. L.; Caplar, R.; Crochet, P.; Dupieux, P.; Dzelalija, M.; Fodor, Z.; Grishkin, Y.; Hong, B.; Kecskemeti, J.; Korolija, M.; Kotte, R.; Lebedev, A.; Lopez, X.; Merschmeyer, M.; Mösner, J.; Neubert, W.; Pelte, D.; Petrovici, M.; Rami, F.; de Schauenburg, B.; Seres, Z.; Sikora, B.; Sim, K. S.; Simion, V.; Siwek-Wilczynska, K.; Smolyankin, S.; Stockmeier, M.; Stoicea, G.; Wagner, P.; Wisniewski, K.; Wohlfarth, D.; Yushmanov, I.; Zhilin, A.;
We present a complete systematics (excitation functions and system-size dependences) of global stopping and sideflow for heavy ion reactions in the energy range between 0.09A GeV and 1.93A GeV. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of sideflow.

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Publ.-Id: 5838


Hochauflösende RBS an ultradünnen Multischichten

in Russian
Mäder, M.; Grötzschel, R.; Klein, C.;
Die hochauflösende Rutherford Rückstreu-Spektrometrie (HRBS) hat ein großes Potential bei der Charakterisierung von dünnen Schichten mit Dicken im Nanometer-Bereich bis hin zu Dicken im Monolagen-Bereich. Der Bedarf der Materialforschung an quantitativen, schnellen und zuverlässigen Tiefenprofilen solcher Proben wächst ständig. Der wesentliche Unterschied zur weit verbreiteten Standard-RBS besteht dabei im Einsatz von Spektrometern in Verbindung mit ortsauflösenden Detektoren. Diese Konfiguration bietet zum einen die Möglichkeit einer verbesserten Energieauflösung bei der Detektion der gestreuten Ionen. Zum anderen ist die Verwendung schwerer Primärionen, deren größeres Bremsvermögen eine bessere Tiefenauflösung erlaubt, damit erst ohne nennenswerte Einschränkungen der Energieauflösung möglich. Die Verwendung von Spektrometern bringt es allerdings mit sich, dass Ionen mit verschiedenen Ladungszuständen getrennt gemessen werden müssen.
Messungen an Mehrfachschichtsystemen mit Li und C als Primärionen illustrieren die Tiefenauflösung im Tiefenbereich bis 20 nm, die mit der HRBS am Rossendorfer Browne-Buechner-Spektrometer erreicht werden kann. An einem einfachen Schichtsystem mit sehr dünnen Einzelschichten werden die exzellenten Möglichkeiten der HRBS im Vergleich zur Standard-RBS und zur MEIS vorgeführt. Die Auswertung der HRBS-Spektren liefert auch Aussagen über das Straggling und den Energieverlust schwerer Ionen in den untersuchten Materialien. Für C-Ionen wurde der Einfluss der Schädigung während der Messung untersucht. Eine Verwendung von Ionen, welche schwerer als C sind, erweist sich bei den am Rossendorfer Tandetron zur Verfügung stehenden Energien auf Grund der erhöhten Schädigung ohne gleichzeitige Verbesserung der Tiefenauflösung als nicht sinnvoll.
  • Lecture (others)
    Arbeitstreffen "Forschung mit nuklearen Sonden und Ionenstrahlen" FSI-2003, Berlin, 30.09. bis 1.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5837
Publ.-Id: 5837


Hochauflösende Rutherford-Rückstreu-Spektrometrie mit schweren Ionen

Klein, C.;
no abstract
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-390 Oktober 2003

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Publ.-Id: 5836


Short-wavelength intersubband absorption in InP-based material systems

Helm, M.;
kein abstract
Keywords: intersubband absorption, quantum cascade laser
  • Lecture (others)
    Seminarvortrag am Institute of Industrial Science, University of Tokyo, Japan (22.9.2003)

Permalink: https://www.hzdr.de/publications/Publ-5835
Publ.-Id: 5835


Short-wavelength intersubband absorption in InP-based material systems

Georgiev, N.; Dekorsy, T.; Helm, M.; Semtsiv, M. P.; Masselink, W. T.; Biermann, K.; Künzel, H.;
In recent years, several novel material systems (such as II-VI’s and nitrides) have been explored with the goal of achieving intersubband absorption in the 1.5 micron telecommunication wavelength region. This could lead to novel near-infrared modulators, detectors and (quantum cascade) lasers with high modulation frequencies.
We have investigated two different material systems grown on InP substrates:
(1) Heavily strained, but overall strain compensated InxGa1-xAs/AlAs/InyAl1-yAs structures grown by gas-source MBE. Here the conduction band offset between the In0.7Ga0.3As and the pure AlAs is approximately 1.23 eV.
(2) Lattice matched In0.53Ga0.47As/AlAs0.56Sb0.44 structures grown by solid-source MBE, with a conduction band offset of approximately 1.6 eV.
In both systems, absorption wavelengths shorter than 2 micron (0.62 eV photon energy) were observed. In the strained system, we investigated multiple quantum wells (MQW) as well as short-period superlattices. The absorption strength in the MQWs (Fig.1) diminishes dramatically for wells narrower than 20 Å, either due to problems in dopant activation (although the doping was put into the wells), or because the second subband has already moved into the continuum. The short-period superlattices show clear evidence of dispersive minibands as well as a small, but non-negligible s-polarized absorption. X-ray diffraction data show that the individual layers are elastically strained, with an overall strain compensation better than 0.2%.
The MQW structures of the antimonide system (modulation doped) exhibit very strong absorption, not degrading for wells down to 27 Å thickness (Fig. 2). Due to the high barriers, a wavelength shorter than 2 microns can be reached already with this thickness value.
Keywords: intersubband absorption, quantum cascade laser
  • Lecture (Conference)
    7th Int. Conference on Intersubband Transitions in Quantum Wells, 1.-5. Sept. 2003, Evolene, Switzerland (auf CD-ROM publiziert)

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Publ.-Id: 5834


A modified ion sputter source with increased lifetime

Friedrich, M.; Tyrroff, H.;
The Cs sputter ion source HVEE 860-C has shown significant erosion of inner parts after an operation time of some thousand hours. This is caused by Cs ions generated at hot surfaces outside the spherical ioniser surface. The calculated trajectories of these ions and the erosion patterns show an excellent correspondence. The suppression of the disturbing ions has resulted in increased lifetimes of the ion source and an improved focus of the primary Cs ions on the sputter target. The modified sputter ion source is still in operation without any maintenance (about 3000 operating hours at October 2003).
Keywords: Ion Sources, Negative Ions, Electrostatic Accelerators.
  • Lecture (Conference)
    37th Symposium of Northeastern Accelerator Personnel, Strasbourg, 2003
  • Contribution to proceedings
    37th Symposium of Northeastern Accelerator Personnel, Strasbourg, 2003 (auf CD-ROM)

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Permalink: https://www.hzdr.de/publications/Publ-5833
Publ.-Id: 5833


Autoradiographic analyses of 5-HT1A and 5-HT2A receptors after social isolation in mice

Schiller, L.; Jähkel, M.; Kretzschmar, M.; Brust, P.; Oehler, J.;
Social isolation of rodents is used to model human psychopathological processes. In the present study, the effects of intermediate and long term isolation housing on postsynaptic 5-HT1A and 5-HT2A receptors were analyzed in male mice housed in groups or isolation for 4 and 12 weeks. [3H]8-OH-DPAT and [3H]ketanserin were used to label 5-HT1A and 5-HT2A receptors. Four representative sagittal sections (planes 1–4) were scored by in vitro autoradiography. Whereas after 4 weeks of housing both receptor densities were lowered significantly in isolated mice, after 12 weeks of housing only marginal isolation effects were seen. Intermediate isolation reduced 5-HT1A receptors especially in the lateral frontal, parietal and entorhinal cortex (-63%), in the lateral CA1–3 and dentate gyrus region of the hippocampus (-68%), in the basolateral, basomedial, central and medial amygdaloid nuclei (between -38 and -66%), and in the hypothalamus (–28%). 5-HT2A receptors were strongly reduced in the frontal cortex (between -47 and -74%), in the hippocampus (between -47 and -95%), in the striatum (between -66 and -76%), and in the accumbens nucleus (between -59 and -73%) in comparison to group housed control mice. After 12 weeks of isolation in the hippocampus continuously decreased 5-HT1A receptor densities were demonstrated (between -24 and -61%). But increased 5-HT2A receptor densities were seen in the lateral striatum (+86%) compared to control mice. Age-dependent effects were also found. After 12 weeks of group housing the 5-HT1A and 5-HT2A receptor densities were decreased (between -28 and -54%) in all analyzed brain regions in comparison to 4 weeks of group housing. Isolated animals showed diminished 5-HT1A receptor densities in the cortex (-14%) and hippocampus (-15%), but increased 5-HT1A receptor densities in the amygdala (+33%) after 12 weeks. The 5-HT2A receptor densities were increased in all analyzed regions (between +31 and +96%) after 12 weeks of isolation compared to 4 weeks. To explain these dynamic, time-dependent pattern of isolation-induced changes different regulation processes are supposed regarding 5-HT1A and 5-HT2A receptors. Besides metabolism-related adaptation processes also neurotransmitter and hormonal (e.g., glucocorticoid) interactions especially in limbic regions have to be considered.
  • Brain Research 980 (2003) 169-178

Permalink: https://www.hzdr.de/publications/Publ-5832
Publ.-Id: 5832


On the Dynamic Behaviour of a Charging System of a Van de Graaff Belt Generator

Bürger, W.;
The dynamic stability of the voltage of Van de Graaff belt generators depends to a great extend on the internal impedance of the charging current supply and on the dynamic precision of the current measurement. A charging stabilizer with increased dynamic precision based on guard technique was developed. The arrangement and results are explained, a disturbance compensation is discussed.
Keywords: Van de Graaff belt generator, current stabilisation, dynamic behaviour, modellation, disturbance compensation
  • Lecture (Conference)
    Proceedings of the 37th Symposium of North Eastern Accelerator PersonnelIReS Strasbourg 13 - 16 October 2003
  • Contribution to proceedings
    Proceedings of the 37th Symposium of North Eastern Accelerator PersonnelIReS Strasbourg 13 - 16 October 2003

Permalink: https://www.hzdr.de/publications/Publ-5831
Publ.-Id: 5831


Advanced thermal processing of ultrashallow implanted junctionsusing flash lamp annealing

Skorupa, W.; Gebel, T.; Yankov, R. A.; Paul, S.; Lerch, W.; Downey, D. F.; Arevalo, E. A.;
The use of flash lamp annealing for ultra-shallow junction formation in silicon has been described. Low energy boron and arsenic implants have been heat-treated in this way using peak temperatures in the range of 1100o to 1300oC and effective anneal times of 20 ms and 3 ms. Secondary ion mass spectrometry and four point probe measurements have been undertaken to determine the junction depth and the sheet resistance, respectively. Optimum processing conditions have been identified, under which one can obtain combinations of junction depth and sheet resistance values that meet the 90 nm technology node requirements and beyond.
Keywords: semiconductor, silicon, low energy boron implantation, low energy arsenic implantation, flash lamp annealing, ultra shallow junction, thermal processing
  • Journal Electrochemical Society 152(2005)6, G436-G440

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Publ.-Id: 5830


Comparison of the updated solutions of the 6th dynamic AER benchmark - main steam line break in a NPP with VVER-440

Kliem, S.;
The 6th dynamic AER Benchmark is used for the systematic validation of coupled 3D neutron kinetic/thermal hydraulic system codes. It was defined at the 10th AER-Symposium. In this benchmark, a hypothetical double ended break of one main steam line at full power in a VVER-440 plant is investigated. The main thermal hydraulic features are the consideration of incomplete coolant mixing in the lower and upper plenum of the reactor pressure vessel and an asymmetric operation of the feed water system. For the tuning of the different nuclear cross section data used by the participants, an isothermal re-criticality temperature was defined.
First solutions of the benchmark were compared during the 11th AER-Symposium. Due to the considerable spreading of these first results, the participants continued the work on the calculation of the benchmark. Updated solutions were received from VTT Processes Espoo (HEXTRAN/SMABRE), Kurchatov Institute Moscow (BIPR8/ATHLET), NRI Rez (RELAP5-3D) and Forschungszentrum Rossendorf (DYN3D/ATHLET). The solution of KFKI AEKI Budapest (KIKO3D/ATLET) remained unchanged.
The paper gives an overview on the behaviour of the main thermal hydraulic and neutron kinetic parameters in the provided solutions. The differences in the updated solution in comparison to the previous ones are described. Improvements in the modelling of the transient led to a better agreement of a part of the results while for another part the deviations rose up. The sensitivity of the core power behaviour on the secondary side modelling is discussed in detail.
  • Lecture (Conference)
    XIII. AER-Symposium on VVER Physics and Reactor Safety, Dresden, Germany, September 23-26, 2003, Proceedings pp. 413-444
  • Contribution to proceedings
    XIII. AER-Symposium on VVER Physics and Reactor Safety, Dresden, Germany, September 23-26, 2003, Proceedings pp. 413-444

Permalink: https://www.hzdr.de/publications/Publ-5828
Publ.-Id: 5828


Phi meson production in near threshold proton-nucleus collisions

Barz, H.-W.; Zetenyi, M.;
The cross section for production of phi mesons inproton-nucleus reactions is calculatedas a function of the target mass. The decay width of the phi meson is affected by the change of the masses of the phi, K+ and K- mesons in the medium. A strong attractive K- potential leads to a measurable change of the behavior of the cross section as a function of the target mass. Comparison between the kaon and electron decay modes are made.
Keywords: Phi meson production, proton-nucleus collisions, mass dependence of cross section

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Permalink: https://www.hzdr.de/publications/Publ-5827
Publ.-Id: 5827


Electroproduction of Strangeness on Light Nuclei

Dohrmann, F.; Abbott, D.; Ahmidouch, A.; Ambrozewicz, P.; Armstrong, C. S.; Arrington, J.; Asaturyan, R.; Assamagan, K.; Avery, S.; Bailey, K.; Baker, O. K.; Beedoe, S.; Bitao, H.; Breuer, H.; Brown, D. S.; Carlini, R.; Cha, J.; Chant, N.; Christy, E.; Cochran, A.; Cole, L.; Collins, G.; Cothran, C.; Crowder, J.; Cummings, W. J.; Danagoulian, S.; Duncan, F.; Dunne, J.; Dutta, D.; Eden, T.; Elaasar, M.; Ent, R.; Ewell, L.; Fenker, H.; Fortune, H. T.; Fujii, Y.; Gan, L.; Gao, H.; Garrow, K.; Geesaman, D. F.; Gueye, P.; Gustafsson, K.; Hafidi, K.; Hansen, J. O.; Hinton, W.; Jackson, H. E.; Juengst, H.; Keppel, C.; Klein, A.; Koltenuk, D.; Liang, Y.; Liu, J. H.; Lung, A.; Mack, D.; Madey, R.; Markowitz, P.; Martoff, C. J.; Meekins, D.; Mitchell, J.; Miyoshi, T.; Mkrtchyan, H.; Mohring, R.; Mtingwa, S. K.; Mueller, B.; O'Neill, T. J.; Niculescu, G.; Niculescu, I.; Potterveld, D. H.; Price, J. W.; Raue, B. A.; Reimer, P. E.; Reinhold, J.; Roche, J.; Roos, P.; Sarsour, M.; Sato, Y.; Savage, G.; Sawafta, R.; Segel, R. E.; Semenov, A. Y.; Stepanyan, S.; Tadevosian, V.; Tajima, S.; Tang, L.; Terburg, B.; Uzzle, A.; Wood, S.; Yamaguchi, H.; Yan-1, C.; Yan-2, C.; Yuan, L.; Zeier, M.; Zeidman, B.; Zihlmann, B.;
The A(e,e'K+)YX reaction has been investigated in Hall C at Jefferson Laboratory. Data were taken for Q^2= 0.35 and 0.5 GeV^2 at a beam energy of 3.245 GeV for 1H,2H,3He, 4He targets. The missing mass spectra are fitted with Monte Carlo simulations taking into account the production of Lambda and Sigma0 hyperon production off the proton, and Sigma- off the neutron. Models for quasifree production are compared to the data, excess yields close to threshold are attributed to FSI. Evidence for Lambda-hypernuclear bound states is seen for 3,4 He targets. This is the first time, the electroproduction of these hypernuclei has been measured.
Keywords: Electroproduction, Strangeness, Hyperons, Hypernuclear boundstates
  • Lecture (Conference)
    SENDAI 03, International Symposium on Electrophoto-production of Strangeness on Nucleons and Nuclei, June 16-18 2003, Sendai. Japan
  • Contribution to proceedings
    Proceedings of SENDAI 03, International Symposium on Electrophoto-production of Strangeness on Nucleons and Nuclei, 16.-18.06. 2003, Sendai, Japan - Singapore World Scientific 2004, 146-151

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Permalink: https://www.hzdr.de/publications/Publ-5826
Publ.-Id: 5826


Multi-component clustering in VVER-type pressure vessel steels - Thermodynamic aspects and impact on SANS

Gokhman, A.; Böhmert, J.; Ulbricht, A.;
APFIM investigation of irradiated VVER 440-type reactor pressure vessel steels suggests the appearance of multi-component clusters. The effect is surprising from the thermodynamic point of view. Numerical estimations of the negative minimum of the thermodynamic driving forces for a multi-component system are carried out considering a quasi-quaternary system consisting of Fe, Mn, Si and vacancies. A relative minimum was only found for a composite model of the multi-component clusters composed from a Fe containing core and a vacancies-rich shell. Such structures can agree with the small angle neutron scattering curves measured. On the other hand, the scattering curves do not provide features which prove the existence of core-shell-structures.
Keywords: Radiation, neutron embrittlement, small angle neutron scattering, radiation defects

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Permalink: https://www.hzdr.de/publications/Publ-5825
Publ.-Id: 5825


Depth-related microstructure of Rf plasma nitrocarburized austenitic stainless steel

Abd El-Rahman, A. M.; Negm, N. Z.; Prokert, F.; El-Hossary, F. M.; Richter, E.; Möller, W.;
The depth dependence of elemental composition, phase distribution, and cross sectional morphology of rf plasma nitrocarburized 304 austenitic stainless steel were investigated using glow discharge optical spectroscopy (GDOS), grazing incidence X-ray
diffraction (GIXRD), and optical microscope (OM), respectively. A step-wise mechanically polishing method was used to remove successive sublayers of the treated surface. It is found that the properties of the nitrocarburized layer depend critically on the plasma gas composition, which controls the supersaturation of nitrogen and carbon through the compound layer depth. Iron nitride phases and/or nitrogen expanded austenite phase (gN) were detected in the nitrocarburized layer prepared at high plasma nitrogen (N2) content. In the compound layer processed at high plasma carbon (C2H2) content, besides the carbon expanded austenite phase (gC), carbide phases were found predominantly in the top-layer, in which the carbon concentration has a maximum value of ~2 wt. %. The lattice expansion of the expanded austenite phases depends on the depth with the variation of the local nitrogen and carbon content. The plasma processing power has enormous influence on the nitrogen and carbon distribution in treated sublayers.

Keywords: Nitrocarburising; 304 austenitic stainless steel; GDOS; Depth microstructure.

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Permalink: https://www.hzdr.de/publications/Publ-5824
Publ.-Id: 5824


Enhancement in redox and electrocatalytic activity observed on Si ion-implanted Ni

Pham, M. T.; Maitz, M.; Richter, E.; Reuther, H.; Mücklich, A.; Prokert, F.;
Ni was surface-alloyed with Si by ion implantation. The material was examined for its redox and electrocatalytic behaviour in NaOH by cyclic voltammetry. The surface war characterized by X-ray photoelectron spectroscopy, X-ray and electron diffraction, and electron and atomic force microscopy. The activity toward the redox conversion of Ni(OH)2 " NiOOH and the anodic oxidation of glucose was enhanced by ca. 3.5 times and ca. 2.8 times, respectively. The material is an amorphous mixed oxide of Ni and Si. The effect was discussed considering the true surface area and the generation of active surface sites in relation to the oxygen evolution.
Keywords: Si-Ni alloy electrodes, electrocatalysis, glucose, surface alloying, ion implantation
  • Journal of Materials Research 19(2004)2, 616-622

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Permalink: https://www.hzdr.de/publications/Publ-5823
Publ.-Id: 5823


Analysis of a PWR core baffle considering irradiation induced creep

Altstadt, E.; Kumpf, H.; Weiß, F.-P.; Fischer, E.; Nagel, G.; Sgarz, G.;
The core baffle of a PWR is loaded by the pressure difference between bypass and core and by temperature profiles developing from gamma and neutron heating and heat transfer into the coolant. Strain, deformation and gaps between the sheets resulting from this load are determined considering the effect of neutron irradiation induced creep of the core baf-fle bolts. The finite element code ANSYS is applied for the thermal and mechanical analyses. The FE-model comprises a complete 45° sector of the core baffle structure in-cluding the core barrel, the formers, the core baffle sheets and about 230 bolt connections with non-linear contact between the single components and the effect of friction. The com-plete analysis requires three major steps:
1. Evaluation of the three dimensional distribution of neutron flux and gamma in-duced internal heating with the Monte Carlo code MCNP®. These calculations are based on pin wise power distributions at the core edge for typical loading patterns.
2. Calculation of the temperature distribution in the core baffle for different opera-tional conditions and core loading patterns, considering heat conduction in the components with internal heat sources and convectional boundary conditions (heat transfer coefficients and bulk temperature of the coolant).
3. Calculation of time dependent deformation, stresses and strains taking into account weight, pressure loads, temperature fields for different load situations, prestressing, irradiation induced creep of the bolts as correlated to neutron flux.
The results show the equalizing effect of redistribution of bolt loads from high flux to lower flux exposure locations in a self controlled process, keeping the mechanical and geometrical stability of the core baffle structure and leaving the gaps between sheet edges unaffected.
Keywords: Pressurized water rector, Core baffle, Irradiation induced creep, Gamma heating
  • Annals of Nuclear Energy 31(2004)7, 723-736

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Permalink: https://www.hzdr.de/publications/Publ-5822
Publ.-Id: 5822


Equipment for beam diagnostics

Friedrich, M.;
In the paper the experiences of more than 30 years operation and development at the electrostatic accelerators at the Forschungszentrum Rossendorf, Dresden/Germany are summarized and focused on the necessary equipment for beam diagnostics at electrostatic accelerators, especially for measurement and monitoring of the current, position, stability and profile of the ion beam.
Keywords: Accelerator, Beam diagnostics
  • Contribution to external collection
    R. Hellborg: Electrostatic Accelerators - Fundamentals and Applications, Berlin Heidelberg: Springer, 2005, 3-540-23983-9, 317-327

Permalink: https://www.hzdr.de/publications/Publ-5821
Publ.-Id: 5821


Superconducting RF guns for FELs

Janssen, D.; Büttig, H.; Evtushenko, P.; Lehnert, U.; Michel, P.; Möller, K.; Schneider, C.; Stephan, J.; Teichert, J.; Kruchkov, S.; Myskin, O.; Tribendis, A.; Volkov, V.; Sandner, W.; Will, I.; Quast, T.; Goldammer, K.; Marhauser, F.; Ylä-Oijala, P.;
The paper provides an overview of the advantages and problems of superconducting RF guns. The results of the Rossendorf experiments are presented here. These results are integrated in the design of a new 3.4 cell superconducting RF gun. The beam parameters of this gun correspond to the demands of the new generation of high current, high brightness injectors.
Keywords: Cavity; Superconductivity; Photocathode; Laser; Electron gun
  • Lecture (Conference)
    AES Meeting,13.01.2004, Medford, USA
  • Nuclear Instruments and Methods in Physics Research Section A, 528(2004)1-2, 305-311
    DOI: 10.1016/j.nima.2004.04.076
  • Contribution to proceedings
    25th International Free Electron Laser Conference, and the 10th FEL Users Workshop, 08.-12.09.2003, Tsukuba, Ibaraki, Japan
    41.60.Cr; 41.75.Fr; 42.55.Xi; 82.25.-j

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Permalink: https://www.hzdr.de/publications/Publ-5820
Publ.-Id: 5820


Chirality of rotating nuclei

Dimitrov, V. I.; Frauendorf, S.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the third International Conference on Fission and Properties of Neutron-Rich Nuclei, Sanibel Island, Florida, 2002, World Science Pub., 1(2003), p. 93

Permalink: https://www.hzdr.de/publications/Publ-5819
Publ.-Id: 5819


Temperature-induced pair correlations in cluster and nuclei

Frauendorf, S.; Kuzmenko, N. K.; Mikhailov, V. M.; Sheikh, J. A.;
The pair correlations in mesoscopic systems such as nanometer-size superconducting clusters and nuclei are studied at a finite temperature for the canonical ensemble of fermions in model spaces with a fixed particle number: (i) a degenerate spherical shell (strong-coupling limit), (ii) an equidistantly spaced deformed shell (weak-coupling limit). It is shown that after the destruction of the pair correlations at T = 0 by a strong magnetic field or rapid rotation, heating can bring them back. This phenomenon is a consequence of the fixed number of fermions in the canonical ensemble.

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Permalink: https://www.hzdr.de/publications/Publ-5818
Publ.-Id: 5818


Cranked relativistic Hartree-Bogoliubov theory: probing the gateway to superheavy nuclei

Afanasjev, A. V.; Khoo, T. L.; Frauendorf, S. G.; Lalazissis, G. A.; Ahmad, I.;
The cranked relativistic Hartree-Bogoliubov theory has been applied for a systematic study of the nuclei around 254No, the heaviest element for which detailed spectroscopic data are available. The deformation, rotational response, pairing correlations, quasiparticle, and other properties of these nuclei have been studied with different parametrizations for the effective mean-field Lagrangian. Pairing correlations are taken into account by a finite range two-body force of Gogny type. While the deformation properties are well reproduced, the calculations reveal some deficiencies of the effective forces both in the particle-hole and particle-particle channels. For the first time, the quasiparticle spectra of odd deformed nuclei have been calculated in a fully self-consistent way within the framework of the relativistic mean field (RMF) theory. The energies of the spherical subshells, from which active deformed states of these nuclei emerge, are described with an accuracy better than 0.5 MeV for most of the subshells with the NL1 and NL3 parametrizations. However, for a few subshells the discrepancies reach 0.7¿1.0 MeV. In very heavy systems, where the level density is high, this level of accuracy is not sufficient for reliable predictions of the location of relatively small deformed shell gaps. The calculated moments of inertia reveal only small sensitivity to the RMF parametrization and, thus, to differences in the single-particle structure. However, in contrast to lighter systems, it is necessary to decrease the strength of the D1S Gogny force in the pairing channel in order to reproduce the moments of inertia.

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Permalink: https://www.hzdr.de/publications/Publ-5817
Publ.-Id: 5817


Evidence for isovector neutron-proton pairing from high-spin states in N = Z 74Rb

O´Leary, C. D.; Svensson, C. E.; Frauendorf, S. G.; Afanasjev, A. V.; Appelbe, D. E.; Austin, R. A. E.; Ball, G. C.; Cameron, J. A.; Clark, R. M.; Cromaz, M.; Fallon, P.; Hodgson, D. F.; Kelsall, N. S.; Macciavelli, A. O.; Ragnarsson, I.; Sarantites, D.; Waddington, J. C.; Wadsworth, R.;
kein Abstract
  • Phys. Rev. C67, 021301 (R) (2003)

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Publ.-Id: 5816


Monitoring postradiotherapeutic changes of lung tissue with CTR, PET and SPECT

Beuthien-Baumann, B.; Eckhardt, M.; Herrmann, T.; Hliscs, R.; van den Hoff, J.; Kumpf, R.; Blank, H.; Baumann, M.;
  • Abstract in refereed journal
    12th International Congress of Radiation Research, 17.-22.08.2003 in Brisbane, Australia; Abstract book (2003) p270
  • Poster
    12th International Congress of Radiation Research; Brisbane, Australia, 17.-22.08.2003

Permalink: https://www.hzdr.de/publications/Publ-5815
Publ.-Id: 5815


In-band and inter-band B (E2) values within the triaxial projected shell model

Boutachkov, P.; Aprahamian, A.; Sun, Y.; Sheikh, J. A.; Frauendorf, S.;
kein Abstract
  • Eur. Phys. Journal A 15, 455 (2002)

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Publ.-Id: 5814


Regional cerebral metabolism in unipolar depression: the relationship with clinical characteristics

Beuthien-Baumann, B.; Zündorf, G.; Lüdecke, S.; Triemer, A.; Schierz, K.; Herholz, K.; Holthoff, V. A.;
  • Abstract in refereed journal
    Brain and BrainPET 2003, 29.06.-03.07.2003 in Calgary, Canada; J Cereb Blood Flow Metabol (2003) 23 Suppl1 p642
  • Poster
    Brain and BrainPET 2003; Calgary, Canada, 29.06.-03.07.2003

Permalink: https://www.hzdr.de/publications/Publ-5813
Publ.-Id: 5813


Observation of a doublet band in the nucleus 128Pr

Petrache, C. M.; Lo Bianco, G.; Bazzacco, D.; Menegazzo, R.; Nespolo, M.; de Angelis, G.; Blasi, N.; Dimitrov, V. I.; Frauendorf, S. G.; Semmes, P.;
kein Abstract
  • Phys. Rev. C65, 054324 (2002)

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Publ.-Id: 5812


Behavioral disturbances and regional cerebral metabolism in probable Alzheimer´s Disease

Holthoff, V. A.; Herholz, K.; Lüdecke, S.; Spirling, S.; Kalbe, E.; Lenz, O.; Zündorf, G.; Beuthien-Baumann, B.;
  • Abstract in refereed journal
    Brain and BrainPET 2003, 29.06.-03.07.2003 in Calgary, Canada; J Cereb Blood Flow Metabol (2003) 23 Suppl1 p631
  • Poster
    Brain and BrainPET 2003; Calgary, Canada, 29.06.-03.07.2003

Permalink: https://www.hzdr.de/publications/Publ-5811
Publ.-Id: 5811


Monitoring postradiotherapeutic changes of lung tissue with PET and SPECT

Beuthien-Baumann, B.; Eckhardt, M.; Herrmann, T.; Hliscs, R.; Oehme, L.; van den Hoff, J.; Kumpf, R.; Geyer, P.; Blank, H.; Baumann, M.;
  • Abstract in refereed journal
    International Congress of Translational Research, 16.-18.03.2003 in Lugano, Int J Radiat Oncol Biol Physics (Suppl.) (2003): 499
  • Poster
    International Congress of Translation Research; Lugano, 16.-18.03.2003

Permalink: https://www.hzdr.de/publications/Publ-5810
Publ.-Id: 5810


Major-Depression im höheren Lebensalter: Regionale Hirnfunktion und kognitive Leistungsfähigkeit in Abhängigkeit vom Erkrankungsalter

Holthoff, V. A.; Lüdecke, S.; Beuthien-Baumann, B.; Zündorf, G.; Triemer, A.; Schellong, J.;
  • Abstract in refereed journal
    6. Jahrestagung der Deutschen Gesellschaft für Gerontopsychiatrie und -psychotherapie e. V. 2.-5. April 2003 in München
  • Lecture (Conference)
    6. Jahrestagung der Deutschen Gesellschaft für Gerontopsychiatrie und -psychotherapie e. V. 2.-5. April 2003 in München

Permalink: https://www.hzdr.de/publications/Publ-5809
Publ.-Id: 5809


High-spin studies of N ~ Z Nuclei in the mass 70 region

Kelsall, N. S.; Svensson, C. E.; Fisher, S.; Appelbe, D. E.; Austin, R. A. E.; Balamuth, D. P.; Ball, G. C.; Cameron, J. A.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Deleplanque, M. A.; Diamond, R. M.; Durell, J. L.; Fallon, P.; Freeman, S. J.; Hausladen, P. A.; Hodgson, D. F.; Janssens, R. V. F.; Jenkins, D. G.; Lane, G. J.; Leddy, M. J.; Lister, C. J.; Macchiavelli, A. O.; O`Leary, C. D.; Sarantites, D. G.; Stephens, F. S.; Schmidt, D. C.; Seweryniak, D.; Varley, B. J.; Vincent, S.; Vetter, K.; Waddington, J. C.; Warsworth, R.; Ward, D.; Wilson, A. N.; Afanasjev, A. V.; Frauendorf, S. G.; Ragnarsson, I.; Wyss, R.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the Conference on Frontiers of Nuclear Structure, Berkeley, California, 2002, UC Berkeley, Clark Kerr Campus, 261 (2003)

Permalink: https://www.hzdr.de/publications/Publ-5808
Publ.-Id: 5808


Gross shell structure of moments of inertia

Deleplanque, M. A.; Frauendorf, S.; Pashkevich, V. V.; Chu, S. Y.; Unzhakova, A.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the Conference on Frontiers of Nuclear Structure, Berkeley, California, 2002, UC Berkeley, Clark Kerr Campus, 105 (2003)

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Publ.-Id: 5806


Left-handed nuclei

Dimitrov, V.; Dönau, F.; Frauendorf, S.; Zhang, J.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the Conference on Frontiers of Nuclear Structures, Berkeley, California, 2002, UC Berkeley, Clark Kerr Campus, 105 (2003)
  • Lecture (Conference)
    Colloquium, Dep. Phys. and Astronomy, 27.10.2005, Nashville, USA

Permalink: https://www.hzdr.de/publications/Publ-5805
Publ.-Id: 5805


Probing the gateway to superheavy nuclei in cranked relativistic Hartree-Bogoliubov theory

Afanasjev, A. V.; Khoo, T. L.; Frauendorf, S.; Lalazissis, G. A.; Ahmad, I.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the Conference on Frontiers of Nuclear Structure, Berkeley, California, 2002, UC Berkeley, Clark Kerr Campus, 379 (2003)

Permalink: https://www.hzdr.de/publications/Publ-5804
Publ.-Id: 5804


Rotating nuclei in the relativistic mean field theory: Microscopic nature of nuclear magnetism

Afanasjev, A. V.; Frauendorf, S. G.; Ring, P.;
kein Abstract
  • Contribution to proceedings
    Proceedings of the NATO Advanced Research Workshop on "The Nuclear Many-Body Problem 2001", Brijuni, Pula, Croatia, 2001, Eds. W. Nazarewicz and D. Vretenar, NATO Science Series II-Math., Phys. and Chem. (Kluwer Academic Publ.) v. 53 (2002) 103-111

Permalink: https://www.hzdr.de/publications/Publ-5803
Publ.-Id: 5803


Evidence for magnetic rotation in the light tin region

Wadsworth, R.; Camaron, J. A.; Clark, R. M.; Frauendorf, S.; (Editors)
kein Abstract
  • Phys. Scripta T88 (2000) 49

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Publ.-Id: 5802


A hybrid version of the tilted axis cranking model and its application to 128Ba

Dimitrov, V. I.; Dönau, F.; Frauendorf, S.;
kein Abstract
  • Phys. Rev. C62 (2000) 024315

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Publ.-Id: 5801


Chirality of nuclear rotation

Dimitrov, V. I.; Frauendorf, S. G.; Dönau, F.;
kein Abstract
  • Physical Review Letters 84 (2000) 5732
  • Lecture (Conference)
    Annual meeting of the Division of Nuclear Physics, 01.04.2004, Bejing, China

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Publ.-Id: 5800


Symmetry breaking by neutron-proton pairing

Frauendorf, S. G.; Sheikh, J.;
kein Abstract
  • Phys. Scripta T88(2000)162

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Publ.-Id: 5799


Description of multi quasiparticle bands by the tilted axis cranking

Frauendorf, S. G.;
kein Abstract
  • Nucl. Phys. A677 (2000) 115

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Publ.-Id: 5797


Moment of inertia for multi-quasiparticle configurations

Frauendorf, S. G.; Sheikh, J. A.; Walker, P. M.; Neergard, K.;
kein Abstract
  • Phys. Rev. C61 (2000) 064324

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Publ.-Id: 5796


Shears mechanism in 109Cd

Chiara, C. J.; Asztalos, S. J.; Busse, B.; Clark, R. M.; Cromaz, M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Fossan, D. B.; Jenkins, D. G.; Juutinen, S.; Kelsall, N. S.; Krücken, R.; Lane, G. J.; Lee, I. Y.; Macchiavelli, A. O.; Macleod, R. W.; Schmid, G.; Sears, J. M.; Smith, J. F.; Stephens, F. S.; Vetter, K.; Wadsworth, R.; Frauendorf, S. G.;
kein Abstract
  • Phys. Rev. C61(2000) 034318

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Publ.-Id: 5795


Evidence for Shears Bands in 108Cd

Kelsall, N. S.; Wadsworth, R.; Asztalos, S. J.; Busse, B.; Chiara, C. J.; Clark, R. M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Fossan, D. B.; Jenkins, D. G.; Juutinen, S.; Krücken, R.; Lane, G. J.; Lee, I. Y.; Macchiavelli, A. O.; Parry, C. M.; Schmid, R. W.; Sears, J. M.; Stephens, F. S.; Smith, J. F.; Vetter, K.; Frauendorf, S. G.;
kein Abstract
  • Phys. Rev. C61(2000) 011301(R)

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Publ.-Id: 5794


Evidence for Shears Bands in 108Cd

Kelsall, N. S.; Wadsworth, R.; Asztalos, S. J.; Busse, B.; Chiara, C. J.; Clark, R. M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Fossan, D. B.;
kein Abstract
  • Phys. Rev. C61 (2000) 034318

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Permalink: https://www.hzdr.de/publications/Publ-5792
Publ.-Id: 5792


Oxidativ modifizierte Lipoproteine und deren Antikörper bei Patienten mit Antiphospholipid-Syndrom

Roch, B.; Kopprasch, S.; Pietzsch, J.; Schröder, H.;
Das Antiphospholipidsyndrom (APS), mit den typischen klinischen Manifestationen von rezidivierenden Thrombosen und Aborten, wird laborchemisch durch das Vorkommen von Antiphospholipidantikörpern (aPL) definiert. Das Krankheitsbild gewinnt in letzter Zeit als mögliches Bindeglied zwischen Autoimmunität und Atherosklerose zunehmend an Bedeutung. Sowohl aPL, als auch oxidierten low-density Lipoproteinen (oxLDL) und deren Antikörpern (Anti-oxLDL) wird eine pathogenetische Bedeutung in der Atherogenese zugesprochen. In unserer Studie verglichen wir die Serumspiegel von oxLDL und AntioxLDL bei APS-Patienten (20 Patienten primäres/14 sekundäres APS) und nonAPS-Patienten (24 phänotypisch gesunde Kontrollpersonen und 12 Patienten mit Systemischem Lupus erythematodes/ SLE/) und untersuchten Assoziationen dieser Parameter zur Intima-Media-Dicke (IMT), einem klinischen Surrogatparameter der Atherosklerose.
SLE-Patienten mit und ohne APS wiesen signifikant erhöhte Anti-oxLDL-Spiegel im Vergleich zur Kontrollgruppe auf (p = 0,038 bzw. p = 0,007). Dahingegen unterschieden sich die oxLDL-Konzentrationen nicht signifikant bei Kontrollen und Patienten. DieAntioxLDL- Spiegel korrelierten signifikant mit Anticardiolipin- (p = 0,002) und 2-Glykoprotein-IAntikörpern (p < 0,048), jeweils vomIgG-Isotyp. Nur SLE-Patienten ohne APS wiesen eine signifikant erhöhte Produktion reaktiver Sauerstoffspezies (ROS) als Zeichen eines proatherogenen oxidativen Stresses in der Zirkulation auf (p < 0,002). Sowohl die zirkulierenden oxLDL- als auch die AntioxLDL- Spiegel wiesen keine Assoziation zur Atherosklerose, gemessen an der IMT, bei den Patientengruppen auf. Zusammenfassend ergibt sich aus unseren experimentellen Daten kein Hinweis darauf, dass bei APS-Patienten eine durch oxidativen Stress beschleunigte Atherosklerose auftritt.

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Permalink: https://www.hzdr.de/publications/Publ-5791
Publ.-Id: 5791


The pivotal role of scavenger receptor CD36 and phagocyte-derived oxidants in oxidized low density lipoprotein-induced adhesion to endothelial cells

Kopprasch, S.; Pietzsch, J.; Westendorf, T.; Kruse, H.-J.; Graessler, J.;
Adhesion of phagocytes to endothelial cells constitutes a crucial step in atherogenesis. Oxidized low density lipoproteins (LDL) are supposed to facilitate the adhesion process. We investigated the molecular mechanisms by which mildly and extensively hypochlorite-oxidized LDL force adhesion of murine macrophages and human neutrophils to human umbilical venous endothelial cells. After 1 h of co-incubation of macrophages, endothelial cells, and lipoproteins adhesion significantly increased to 160 ± 13 % (S.E.M., n=5) in the presence of mildly oxidized lipoprotein, and 210 ± 11 % (S.E.M., n=5) in the presence of extensively oxidized lipoprotein. Similar results were obtained with neutrophils. CD36 antibody (FA6-152) significantly reduced adhesion to 102 ± 7 % (S.E.M., n=5) using mildly oxidized low density lipoprotein and to 179 ± 16 % (S.E.M., n=5) using extensively oxidized low density lipoprotein. Native high density lipoprotein and to a lesser extent methionine-oxidized high density lipoprotein significantly counteracted the effects of low density lipoprotein. Prior incubation of endothelial cells with modified lipoproteins followed by their removal and subsequent incubation with macrophages or neutrophils resulted in only minor changes of adhesion. This suggests that the direct contact of low density lipoprotein with phagocytes followed by activation of a respiratory burst with release of reactive oxygen species facilitates the adhesion process. Accordingly, the addition of antioxidants (superoxide dismutase and catalase) to the co-incubation medium was followed by a significant decrease in phagocyte adhesion. It is concluded that oxidized low density lipoprotein-induced respiratory burst activation of phagocytes with subsequent release of oxidants constitutes a crucial step in promoting the adhesion of phagocytes to endothelial cells.
Keywords: Phagocyte, Adhesion, Reactive oxygen species, Oxidized LDL, Endothelial, Cell, HDL, CD36
  • International Journal of Biochemistry and Cell Biology 36(2004)3, 460-471

Permalink: https://www.hzdr.de/publications/Publ-5790
Publ.-Id: 5790


Validation of different chemilumigenic substrates for detecting extracellular generation of reactive oxygen species by phagocytes and endothelial cells

Kopprasch, S.; Pietzsch, J.; Graessler, J.;
  • Luminescence (2003) 18: 268-273

Permalink: https://www.hzdr.de/publications/Publ-5789
Publ.-Id: 5789


The protective effects of HDL and its constituents against neutrophil respiratory bust activation by hypochlirite-oxidized LDL

Kopprasch, S.; Pietzsch, J.; Graessler, J.;
Hypochlorite-oxidized low-density lipoprotein (oxLDL) possesses a substantial proinflammatory potential by modulating respiratory burst activities of polymorphonuclear neutrophils (PMN). As evaluated by luminol-amplified chemiluminescence (CL) incubation of 106 PMN/ml with 70 nM oxLDL was followed by substantial induction of neutrophil oxidant (ROS) generation. We evaluated the inhibitory capacity of high-density lipoprotein (HDL) and its lipid and protein constituents against the activating effects of oxLDL. At a HDL or apolipoprotein AI/LDL protein ratio of 1.0, native HDL decreased the respiratory burst activation by 64 %, followed by trypsinized HDL (57 %) and native apoAI (43 %). The inhibitory effects of native HDL did not require prior incubation with PMN or with oxLDL suggesting an instantaneously acting protective mechanism in the minute range. OxLDL modulated ROS production not only of resting PMN but also that of activated PMN, as indicated by a 14-fold increase in FMLP-stimulated CL response and a 50 % decreased in zymosan-mediated CL answer. HDL itself did not protect PMN from activation by FMLP and zymosan. However, it clearly reduced effects of oxLDL on FMLP-activation and slightly counteracted the oxLDL-mediated decrease in zymosan-induced ROS generation. Taken together, these findings may offer new insight into atheroprotective mechanisms of HDL.
Keywords: atherosclerosis, oxidized low-density lipoprotein, hypochlorite, high-density lipoprotein, neutrophils, respiratory burst
  • Molecular and Cellular Biochemistry 258(2004), 121-127

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Publ.-Id: 5788


Analysis of non-protein amino acids as specific markers of low density lipoprotein apolipoprotein B-100 oxidation in human atherosclerotic lesions: the use of N(O,S)-ethoxycarbonyl trifluoroethyl ester derivatives and GC-MS

Pietzsch, J.; Bergmann, R.; Kopprasch, S.;
Oxidative modification of proteins can interfere with critical cellular functions, and is widely regarded as a crucial event in the pathogenesis of various diseases ranging from rheumatoid arthritis to atherosclerosis and cancer. In this line, a new GC-MS methodology using N(O)-ethoxycarbonyl trifluoroethyl amino acid esters (ECEE-F-3) for rapid and sensitive determination of 3-chlorotyrosine, 5-hydroxy-2-aminovaleric acid (HAVA), and 6-hydroxy-2-aminocaproic acid (HACA) in proteins has been developed. 3-Chlorotyrosine is a highly specific marker of myeloperoxidase catalyzed protein oxidation, whereas gamma-glutamyl semialdehyde (gammaGSA) and alpha-aminoadipyl semialdehyde (alphaASA), which by reduction form HAVA and HACA, respectively, are specifically formed by metal catalyzed oxidation processes. ECEE-F3 derivatives are formed by the unlabored reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. The key steps of the methodology employed are (i) enzymatic hydrolysis of target proteins to prevent decomposition of oxidation products during hydrolysis and (ii) an uniquely rapid derivatization of amino acids completing sample preparation for GC within a few minutes in aqueous solution at room temperature. The use of these stable products of protein amino acid side chain oxidation as potential markers for assessing oxidative damage in LDL apoB-100 recovered from human aortic vascular lesions is demonstrated. These observations provide quantitative chemical evidence for metal catalyzed oxidative processes in the human artery wall.
  • Spectroscopy 18(2004),177-183

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Publ.-Id: 5787


Analysis of 6-hydroxy-2-aminocaproic acid (HACA) as a specific marker of protein oxidation: The use of N(O,S)-ethoxycarbonyl trifluoroethyl ester derivatives and gas chromatography/mass spectrometry

Pietzsch, J.; Bergmann, R.;
Summary. An alteration of low density lipoprotein (LDL) apolipoprotein (apo) B-100 structure by direct oxidative modification is an important mechanism involved in atherogenesis. There is difficulty in quantifying this type of modification because a lack of specific assays. The use of N(O,S)-ethoxycarbonyl trifluoroethyl amino acid esters for a rapid and sensitive determination of 6-hydroxy-2-aminocaproic acid (HACA), a highly specific marker of metal catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. The derivatives are formed by the unlabored reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. Femtomole levels of HACA can be reproducible measured in different LDL preparations subjected to oxidative damage in the presence of iron or copper. HACA determination compares well with the measurement of carbonyl groups that are generally accepted as a nonspecific index of protein oxidation. Thus, the method could prove to be a sensitive assay for studying specific apoB-100 modification.
Keywords: Amino acids, Hemin, Low density lipoprotein, Protein oxidations, Gas chromatography/mass spectrometry
  • Amino Acids 26(2004), 45-51

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Publ.-Id: 5786


Fortschritte in der Aminosäureanalytik: N(O,S)-Ethoxycarbonyl-(trifluoro)ethylester-Derivate

Pietzsch, J.;
  • Bioforum 10/2003, 643-645

Permalink: https://www.hzdr.de/publications/Publ-5785
Publ.-Id: 5785


Assessment of metabolism of native and oxidized low density lipoprotein in vivo: insights from animal positron emission tomography (PET) studies

Pietzsch, J.; Bergmann, R.; Wüst, F.; Grote, M.; Hultsch, C.; Pawelke, B.; van den Hoff, J.;
Oxidative modification of low density lipoprotein (LDL) is regarded as a crucial event in athergenesis. Data concerning the role of circulating oxidized LDL (oxLDL) in the development of atherosclerosis are scarce. One reason for this is the shortage of methaods for direct assessment of metabolism of oxLDL in vivo. We reprot an improved methodology for labelling of both native LDL (nLDL) and oxLDL with fluorine-18 (18F) by N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) and the use of LDL-[18]FB-conjugates in dynamic PET studies in Wistar rats. For labelling experiments, pools of chemically well characterized human nLDL and oxLDL, respectively, were used. Preparation of [18F]SFB was achieved within 40 min with radiochemical yields of 50±5% and purity of >95% using O-(N-succinimidyl)-N-N,N´,N´-tetramethyluronium tetrafluoroborate (TSTU) as activating reagent. LDL labelling with [18F]SFB resulted in radiochemical yields of 30±10%. The method was evaluated with respect to uptake of FB-conjugated nLDL in HepG2 cells and of FB-conjugated oxLDL in primary human macrophages, respectively. Biodistribution studies revealed high in vivo stability for the LDL-[18F]FB conjugates. The metabolic fate of LDL-[18F]FB conjugates in vivo was delineated by PET using a dedicated small animal tomograph (microPET; spatial resolution of 2 mm). In conclusion, [18F]SFB-labelling of LDL and the use of PET provide a valuable tool for assessment of metabolism of nLDL and oxLDL in vivo.
  • Lecture (Conference)
    8th International Congress on Proteins and Amino Acids, Rome, Italy, 5-9 September 2003
  • Abstract in refereed journal
    Amino Acids (2003) 25: 120

Permalink: https://www.hzdr.de/publications/Publ-5784
Publ.-Id: 5784


Electromagnetic flow control leading to a strong drag reduction of a sphere

Shatrov, V.; Gerbeth, G.;
We consider the flow of an electrically conducting fluid around a sphere with some internal source of alternating magnetic field. The resulting electromagnetic forces of this inductive scheme lead to a thrust of the sphere and a changed drag coefficient which balance each other in the self-moved regime. Allowing for a free choice of physically meaningful field distributions, the inverse problem is addressed of looking for such magnetic fields which result in a low drag. Without claiming to have found a global minimum, we present some examples of electromagnetic forces providing strong reductions of the sphere drag. Numerical results up to Re=1000 are given, the corresponding modifications of surface pressure and vorticity are discussed. The energetic balance is not yet analysed as it requires to consider the coupled hydrodynamic and electromagnetic problems.
  • Fluid Dynamics Research 36(2005), 153-173

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Permalink: https://www.hzdr.de/publications/Publ-5782
Publ.-Id: 5782


Separation control by electromagnetic forces - applications at ships

Gerbeth, G.; Weier, T.;
The flow of electrically conducting fluids can be controlled by electromagnetic forces. Whereas this concept is already in industrial use in metallurgical or crystal growth technologies, its application to flows of electrolytes is less developed yet. For seawater flows around ship components, flow separation is an important phenomenon limiting the operation of, e.g., rudders or stabilizing foils. We present experimental and numerical results on the prevention of flow separation by means of a stream-wise, wall parallel Lorentz force acting on the suction side of inclined flat plates and hydrofoils. The use of steady as well as oscillatory Lorentz forces is considered. The results for oscillating Lorentz forces will be compared to recent literature results for periodic suction/blowing. Scaling relations for an extrapolation to application relevant Reynolds numbers will be given, and the related energy consumption will be analysed.
  • Lecture (others)
    Seoul National University, 07.10.2003

Permalink: https://www.hzdr.de/publications/Publ-5781
Publ.-Id: 5781


Review of the Status of SRF Photo-Injectors

Teichert, J.; Büttig, H.; Evtushenko, P.; Janssen, D.; Lehnert, U.; Michel, P.; Schneider, C.;
Superconducting radio frequency photoelectron injectors open the way to low-emittance electron beams in continuous-wave operation mode. Their progress is essential for future projects of high-power free electron lasers, energy recovery linacs and next generation light sources. In this presentation, the technical issues associated with the design, construction and operation of SRF photo-injectors will be reviewed together with the progress in several laboratories during the past few years. Results of the operation of the Rossendorf SRF photo-injector with an 1.3 GHz niobium half cell and the future projects are discussed in detail.
Keywords: photoelectron-injector electron source superconductivity superconducting cavity rf-photogun srf-photo-injector
  • Lecture (Conference)
    11th Workshop on RF-Sperconductivity SRF 2003, 5 pages, 08. – 12. September 2003, Lübeck/Travemünde, Germany
  • Contribution to proceedings
    11th Workshop on RF-Sperconductivity SRF 2003, 5 pages, 08. – 12. September 2003, Lübeck/Travemünde, Germany

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Permalink: https://www.hzdr.de/publications/Publ-5779
Publ.-Id: 5779


Two-dimensional heterogeneous transport theory hot zero-power benchmarks for the WWER-1000 reactors

Petkov, P. T.; Mittag, S.;
The Mariko code, based on the method of characteristics, has been used to calculate several two-dimensional full core heterogeneous 23-group transport theory solutions for hot zero power states of the WWER-1000 reactor. The initial loading for the three-year fuel cycle is considered. Helios-1.5 has been used to prepare 23-group cross-section data. The benchmarks differ by the positions (up or down) of the control rods groups. The asymptotic assembly-averaged and cell-averaged two-group diffusion parameters for all assembly types, the group-to-group albedos on the radial reflector boundary, and the effective diffusion parameters, including reference discontinuity factors, for the radial reflector nodes are all calculated by Mariko. The accuracy of the SPPS-1.6 and DYN3D nodal diffusion codes and the HEX2DA/B pin-by-pin diffusion codes have been tested. The benchmark with all control rods down poses a great problem for the nodal diffusion codes, the maximum error in the relative assembly-wise power distribution reaching 18% for SPPS-1.6. The pin-by-pin codes perform well in all cases.
  • Lecture (Conference)
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 77-88
  • Contribution to proceedings
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 77-88

Permalink: https://www.hzdr.de/publications/Publ-5778
Publ.-Id: 5778


A new DYN3D library for the WWER-1000 reactors

Petkov, P. T.; Mittag, S.; Christoskov, I.; Kamenov, K.; Antov, A.; Bakalov, I.; Wehner, H.;
A new library of two-group diffusion and kinetics parameters has been generated for the neutron kinetics code DYN3D, intended for analysis of reactivity initiated accidents for the WWER-1000 reactors. All assembly types for the 3-year fuel cycle are included. The Helios-1.5 code and its adapted 190-group library have been used at the stage of the lattice calculations. A generalised code for preparation of Helios input for both types of WWER reactors has been developed. The approximation methodology is based on a combination between interpolation over the moderator temperature and density, and approximation over the rest of the independent state parameters. High accuracy is achieved by applying square interpolation over the moderator temperature and cubical interpolation over the moderator density. The axial/radial reflectors are described by effective diffusion parameters, including reference discontinuity factors, calculated on the base of one/two-dimensional heterogeneous 23-group transport theory solutions by Mariko. DYN3D has been modified in order to use the new library. BIPR-7 results, used for operational neutronics calculations of the WWER-1000 reactors at the Kozloduy NPP, have been used to validate the new library. The kinetics parameters have been validated as well.
  • Lecture (Conference)
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 109-122
  • Contribution to proceedings
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 109-122

Permalink: https://www.hzdr.de/publications/Publ-5777
Publ.-Id: 5777


Validation of Coupled Neutronics / Thermal Hydraulics Codes for VVER Reactors (VALCO)

Weiss, F.-P.; Mittag, S.; Langenbuch, S.; Vanttola, T.; Hämäläinen, A.; Keresztúri, A.; Hádek, J.; Darilek, P.; Petkov, P. T.; Kuchin, A.; Hlbocky, P.; Sico, D.; Danilin, S.; Powney, D.;
The VALCO project aims at the improvement of the validation of coupled neutron-kinetics / thermal-hydraulics codes for VVER reactors. VALCO was started on January 1, 2002 and will be completed December 31, 2003. The project is split into three Work Packages.

In Work Package 1, lead by VTT, the existing data base, containing measured VVER transient data from the former EU Phare project SRR1/95, has been extended by five new transients. Two of these transients were used for the validation of different coupled codes suitable for VVER. The comparison between the codes and the validation against the measurements was successful. The obtained deviations from the experimental data are well understood and mostly caused by missing information about the operational regime during the transient.

A comprehensive uncertainty analysis for the two SRR1/95 transients, one for each a VVER-440 and a VVER-1000, has been carried out in Work Package 2 under the leadership of GRS. An essential result of the analysis is the identification of the input parameters, such as the secondary-circuit pressure, the control-assembly position (as a function of time), and the control-assembly efficiency, that most sensitively affect the safety-relevant output parameters.

In Work Package 3, lead by FZR, stand-alone three-dimensional neutronics codes have been validated against measurements in the Russian V-1000 zero power test facility. After correcting the geometrical input data, a good agreement between calculated and measured steady-state power distributions could be achieved, both for assembly-averaged powers and pin powers. The real time behavior of local power measured during transients is well modeled by the reactor-dynamic codes.
  • Lecture (Conference)
    Symposium FISA-2003 - EU research in reactor safety, European Commission, Luxembourg, 10-13 November 2003, Pre-proceedings pp. 490-495
  • Contribution to proceedings
    Symposium FISA-2003 - EU research in reactor safety, European Commission, Luxembourg, 10-13 November 2003, Pre-proceedings pp. 490-495

Permalink: https://www.hzdr.de/publications/Publ-5776
Publ.-Id: 5776


Specific hemin catalyzed low density lipoprotein ocidation reactions: implications for metabolic and inflammatory diseases

Pietzsch, J.;
Oxidation of LDL and lipids by transition metal catalyzed processes is a key factor in atherogenesis. Clinical and experimental evidence suggests that these processes involve binding of hemin, a product of hemoglobin degradation, to descrete binding sites of LDL thus forming centers for redox cycling and repeated radical production. The mechanisms for these observations remain unclear. In the present study, we found that hemin binds rapidly to low density lipoprotein subfractions (LDL1, 1.019-1.044 kg/L; LDL2, 1.044-1.063 kg/L) with binding rates in the nM range. Spectrosphotometric and fluorescence experinemts indicated that the amphiphilic hemin molecule is buried in the lipoprotein surface monolayer with the carboxylic groups in contact with positively charged surface regions. In vitro, in the presence of H2O2, hemin oxidizes both LDL1 and LDL2 with formation of specific products of oxidation of positively charged protein amino acid residues (gamma-glutamyl semialdehyde and alpha-aminoadipic semialdehyde) and phospholipids (1-palmitoyl-2-oxovaleroyl-sn-glycero-3-phosphorylcholine). The formation of these products was more than twofold higher (p<0.01) when compared with oxidation systems containing free iron or copper. Hemin catalyzed LDL oxidation was inhibited by the iron-chelating agents 1,2-Dimethyl-3-hydroxypyrid-4-one and N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid, respectively. In vivo, a significantly increased formation of all three specific oxidation products could be confirmed in circulating plasma LDL1 and LDL2 particles obtained from patients with impaired glucose tolerance (p<0.05), Type 2 diabetes mellitus (p<0.05), and rheumatoid arthritis (p<0.01) when compared with healthy controls. The rsults provide further evidence on pathophysiological relevance of hemin catalyzed LDL oxidation in metabolic an inflammatory diseases.
  • Abstract in refereed journal
    Amino Acids (2003) 25: 120
  • Lecture (Conference)
    8th International Congress on Proteins and Amino Acids, Rome, Italy, 5-9 September 2003

Permalink: https://www.hzdr.de/publications/Publ-5775
Publ.-Id: 5775


Discontinuity factors for non-multiplying hexagonal nodes in VVER reactors

Mittag, S.; Petkov, P. T.; Grundmann, U.;
On the basis of methods developed recently for square-fuel-assembly reactor cores, discontinuity factors for hexagonal control absorbers (VVER-440) and reflector nodes have been derived. Partial currents from heterogeneous multi-group transport calculations are used for the determination of the discontinuity factors. As shown by suitable benchmark calculations, the application of these quantities in the two-group nodal diffusion code DYN3D clearly improves the results of assembly powers and effective multiplication factors. The advantage of reflector diffusion parameters, including discontinuity factors, over conventional albedos has been demonstrated.
  • Lecture (Conference)
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 89-108
  • Contribution to proceedings
    13. Symposium of AER, Dresden, 22-26 September, 2003, pp. 89-108

Permalink: https://www.hzdr.de/publications/Publ-5774
Publ.-Id: 5774


DYN3D Calculations for the V-1000 Test Facility and Comparisons with the Measurements

Grundmann, U.; Mittag, S.;
In the framework of the EU project VALCO, measurements at the V-1000 test facility of the Russian Research Centre ?Kurtschatov Institute? are used for the validation of three-dimensional neutronic calculations. Experimental results of steady states and kinetic experi-ments are available for comparisons with calculations. Respective DYN3D calculations have been performed by using the cross section libraries generated with the codes HELIOS, CASMO and WIMS.
Results obtained by the DYN3D code are compared with steady-state measurements for two different configurations of the V-1000 facility. Pin-power distributions measured within one fuel assembly are compared to the results of the pin power reconstruction implemented in DYN3D.
Two kinetic experiments performed in the V-1000 facility were calculated with DYN3D. Comparisons of the calculated results with the measurements at the in-core detector positions are given. The calculated fast flux of the nodes, situated near to the ionisation chambers of the two reactimeters, is compared with the detector signal. The reactivities obtained from the core-averaged flux by inverse point kinetics and the reactivity curves, provided by the reac-timeters, are presented and discussed.

Keywords: neutron transport nuclear reactors research reactors neutron kinetics diffusion equation nodal methods measurementss code validation
  • Lecture (Conference)
    Proceedings of 13. Symposium of AER,p. 521-539, Dresden, 22-26. September, 2003
  • Contribution to proceedings
    Proceedings of 13. Symposium of AER,p. 521-539, Dresden, 22-26. September, 2003

Permalink: https://www.hzdr.de/publications/Publ-5773
Publ.-Id: 5773


Therapy of malignant ascites in vivo by 211At-labelled microspheres

Bredow, J.; Kretzschmar, M.; Wunderlich, G.; Dörr, W.; Pohl, T.; Franke, W.-G.; Kotzerke, J.;
Aim: Determination of the biological effect of the alpha emiter 211At on cellular level as well as the assessment of dosimetric data in a tumor model in vivo.
Methods: Transplantation of malignant ascitic cells in mice intraperitoneally and estimation of tumor characteristics (doubling time of the cells, mean survival of the animals following an i.p. applicatin of a defined tumor cell number). 211At labelled human serum albumine microspheres B-20 (MSP) of different activity were injected into tumor bearing mice intraperitoneally. The effectiveness of the therapy was evaluated by means of determination of the duration of cell cycle arrest as well as the microscopic analysis of the rate of abnormal mitotic cells due to radiation induced damage. Furthermore, dose dependence of survival was evaluated.
Results: Three days following the intraperitoneally application of 8 x 106 tumor cells, 50 - 600 kBq 211At-MSP were applied into the abdominal cavity. Derived from the volume of ascites at this time and the administered activity, dese calculations were performed. An activity of 50 kBq caused a dose of 0.84 Gy. The increase of radiation induced effect on ascitic tumor cells was correlated with the dose. Between the duration of the cell cycle arrest and the administered activity, a dirctly proportional correlation was found. The mean survival of non treated animals was 16.9 ± 3.7 days. Teh prolongation of the survival was proportional to the activity administered. Using a dosage of 10 Gy, five animals out of 16 survived.
Conclusion: Therapy of malignant ascitic cells using 211At-MSP was effective in vivo. For tumor therapy, teh alpha emitter 211At represents a highly effective alternative to usually employed beta emitters.
  • Nuklearmedizin 43(2004), 63-68

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Permalink: https://www.hzdr.de/publications/Publ-5771
Publ.-Id: 5771


Phase composition and properties of iron nanocrystals and clusters embended in MgO matrix

Schneeweiss, O.; Pizúrová, N.; Jirásková, Y.; ŽÁk, T.; Bezdicka, P.; Reuther, H.;
Phase composition and properties of iron nanocrystals and clusters embended in MgO matrix
  • Poster
    Int. Conference on the Applications of the Mössbauer Effect, Muscat, Oman, 21.-25.9.2003

Permalink: https://www.hzdr.de/publications/Publ-5770
Publ.-Id: 5770


Low temperature Mössbauereffect studies of c-FeSi films synthesized by molecular beam epitaxy and by ion implantation

Walterfang, M.; Reuther, H.; Keune, W.;
Low temperature Mössbauereffect studies of c-FeSi films synthesized by molecular beam epitaxy and by ion implantation
  • Poster
    Int. Conference on the Applications of the Mössbauer Effect, Muscat, Oman, 21.-25.9.2003

Permalink: https://www.hzdr.de/publications/Publ-5769
Publ.-Id: 5769


Anorganische Kolloide im Wasser der Elbe

Opel, K.; Hüttig, G.; Zänker, H.;
Das Wasser der Elbe auf der Höhe von Dresden enthält anorganische Kolloidpartikel, deren Partikelgrößenverteilung nahezu den gesamten kolloidalen Definitionsbereich (1 nm bis 1 µm) überstreicht und die vor allem aus sekundär ausgeschiedener amorpher Kieselsäure sowie aus Oxyhydroxiden des Fe, Al und Mn bestehen. Als wichtigstes Schwermetall führen sie Zn. Ihre Konzentration liegt unter 5×10-1 mg/l, um etwa Faktor 30 unter der Konzentration der Schwebstoffe des Elbwassers (Partikel >1 µm). Wegen ihrer hohen spezifischen Oberfläche sind die Kolloidpartikel als potentielle Träger für Schadstoffe trotz dieser geringeren Massekonzentration nicht gegenüber den Schwebstoffen zu vernachlässigen. Die in der Elbe gemessene Partikelgrößenverteilung ähnelt derjenigen, die zu einem früheren Zeitpunkt im Rhein gefunden worden war. Auch die chemische Zusammensetzung der Kolloidpartikel in der Elbe ist der der Partikel des Rheins ähnlich. Die Konzentration der Kolloidpartikel in der Elbe war aber um Faktor 5 bis 10 höher als im Rhein. Grund für letzteres ist wahrscheinlich der höhere Gehalt des Elbwassers an gelöstem Kohlenstoff (DOC). Im „Bulk“ eines Flusses sind kolloidgetragene Schadstoffe - anders als schwebstoffgetragene - vermutlich fast genauso mobil wie echt gelöste. Unterschiede zwischen den Transportgeschwindigkeiten der kolloidgetragenen und der echt gelösten Spurenstoffe treten in bestimmten Situationen auf, in denen das Wasser den „Bulk“ eines Flusses verlässt (Sickerbereich unter dem Fluss, Ästuar). Es werden Schlussfolgerungen über die Rolle von Kolloidpartikeln im Ökosystem eines Flusses gezogen und noch bestehende Forschungsdesiderate benannt.
Keywords: colloids, particles, river water, contaminants, photon correlation spectroscopy, centrifugation, filtration, REM, EDX
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-395 Januar 2004

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Permalink: https://www.hzdr.de/publications/Publ-5766
Publ.-Id: 5766


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