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Kornl L. Kovcs Barna Fodor kos T. Kovcs Gyula Csandi Gergely Marti Judit Balogh Solmaz Arvani Gbor Rkhely 《International Journal of Hydrogen Energy》2002,27(11-12)
The purple (Sulphur) phototrophic bacterium, Thiocapsa roseopersicina BBS contains several [NiFe] hydrogenases, of which two are membrane bound. Mutant T. roseopersicina cells, carrying deletions in both gene clusters showed hydrogenase activity. This activity was located in the cytoplasm. The structural gene cluster hoxEFUYH was identified and sequenced. In addition, genes homologous to hupUV/hoxBC, the hydrogen sensing hydrogenase have been identified and sequenced.Regulation of hydrogenase biosynthesis was studied in detail for HydSL (renamed HynSL). A random mutagenesis system was optimised for T. roseopersicina. One of the mutations was in a gene similar to that coding for the HypF proteins in other organisms. Inactivation of the hypF gene resulted in a 60-fold increase in hydrogen evolution under nitrogen fixing conditions. In addition to hypF, the following accessory genes were identified: hydD, hupK, hypC1, hypC2, hypDE. Characterisation of the corresponding gene products and search for additional accessory genes are in progress. 相似文献
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Summary Living carbocationic polymerization of styrene (St) has been achieved by the use of the 1(p-methylphenyl)ethyl acetate (pMePhEtOAc)·BCl3 complex in CH3Cl solvent at –30°C using both the IMA and AMI techniques. The living nature of the polymerizations has been demonstrated by linear Mn versus WPSt (weight of polystyrene) plots passing through the origin and horizontal N (moles of PSt) versus WPSt plots starting at N=Io (the number of moles of initiator used). The molecular weight distribution MWD of the PSts is broad (Mw/Mn=~5–6) due to slow initiation and/or slow exchange between dormant and active species relative to propagation. The structure of the ester initiator strongly affects the rate and outcome of living polymerization, e.g., cumyl acetate (CumOAc), cumyl propionate (CumOPr), and 2,4,6-trimethylphenylethyl acetate (TMePhEtOAc), do not lead to truly living St polymerizations. The findings with the latter esters is explained in terms of a two path process comprising a slow living polymerization and a faster conventional cationic chain reaction. With phenylethyl acetate (PhEtOAc) living polymerization is achieved, however, initiation (cation generation) is slow. Forced termination by pyridine or methanol, or heating to ambient temperature leads to-CH2CH(C6H5)Cl end groups. 相似文献
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Đurović Gordana Van Neerbos Francine A. C. Bossaert Sofie Herrera-Malaver Beatriz Steensels Jan Arnó Judit Wäckers Felix Sobhy Islam S. Verstrepen Kevin J. Jacquemyn Hans Lievens Bart 《Journal of chemical ecology》2021,47(8-9):788-798
Journal of Chemical Ecology - There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore... 相似文献
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The in-situ monitoring of the living carbocationic polymerization of isobutylene (IB) and styrene (St) with a fiber optic
Attenuated Total Reflection (ATR) probe in the mid-IR "fingerprint" range is reported here for the first time. Monomer consumption
was followed by the disappearance of the C=C stretching for both IB and St, and the C−H bending of the CH3-group in IB. The formation of polyisobutylene (PIB) was also monitored by tracing the asymmetrical doublet characteristic
of C−H bending of the t-butyl groups of the PIB. Conversion measurements by conventional off-line gravimetry correlated well with the new technique.
Received: 27 August 1997/Revised version: 2 November 1997/Accepted: 20 November 1997 相似文献
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Judit Bar-Ilan 《Scientometrics》2012,92(2):249-260
The impact factor is one of the most used scientometric indicators. Its proper and improper uses have been discussed extensively before. It has been criticized extensively, yet it is still here. In this paper I propose the journal report card, which is a set of measures, each with an easily comprehensible meaning that provides a fuller picture of the journals?? standing. The set of measures in the report card include the impact factor, the h-index, number of citations at different points on the ranked list of citations, extent of uncitedness and coverage of the h-core. The report card is computed for two sets of journals, the top-20 journals in JCR 2010 and the top-20 journals in JCR 2010 for the category Information and Library Science. 相似文献
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Scientometrics - In a Letter to the Editor, the authors of this paper show, to highlight the practical risks of using the h-index, how academics’ data and bibliometric information can be... 相似文献
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Josefina Pérez-Arantegui Judit Molera Angel Larrea Trinitat Pradell Marius Vendrell-Saz Ilaria Borgia Brunetto G. Brunetti Franco Cariati Paola Fermo Marcello Mellini Antonio Sgamellotti Cecilia Viti 《Journal of the American Ceramic Society》2001,84(2):442-46
Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans. 相似文献