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11.
Valentin Chabert Lucille Babel Michael P. Füeg Maksym Karamash Edwin S. Madivoli Nelly Herault Joana M. Dantas Carlos A. Salgueiro Bernd Giese Katharina M. Fromm 《Angewandte Chemie (International ed. in English)》2020,59(30):12331-12336
Anaerobic microorganisms of the Geobacter genus are effective electron sources for the synthesis of nanoparticles, for bioremediation of polluted water, and for the production of electricity in fuel cells. In multistep reactions, electrons are transferred via iron/heme cofactors of c‐type cytochromes from the inner cell membrane to extracellular metal ions, which are bound to outer membrane cytochromes. We measured electron production and electron flux rates to 5×105 e s?1 per G. sulfurreducens. Remarkably, these rates are independent of the oxidants, and follow zero order kinetics. It turned out that the microorganisms regulate electron flux rates by increasing their Fe2+/Fe3+ ratios in the multiheme cytochromes whenever the activity of the extracellular metal oxidants is diminished. By this mechanism the respiration remains constant even when oxidizing conditions are changing. This homeostasis is a vital condition for living systems, and makes G. sulfurreducens a versatile electron source. 相似文献
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The correspondence principle between the quantum commutator [A, B] and the classical Poisson brackets iota h{A, B} is examined in the context of response theory. The classical response function is obtained as the leading term of the expansion of the phase space representation of the response function in terms of Weyl-Wigner transformations and is shown to increase without bound at long times as a result of ignoring divergent higher-order contributions. Systematical inclusion of higher-order contributions improves the accuracy of the h expansion at finite times. Resummation of all the higher-order terms establishes the classical-quantum correspondence <--> alpha n e iota n omega t|Jv + nh/2. The time interval of the validity of the simple classical limit [A(t), B(0)] --> iota h{A(t), B(0)} is estimated for quasiperiodic dynamics and is shown to be inversely proportional to anharmonicity. 相似文献
14.
A. I. Kuklin A. D. Rogov Yu. E. Gorshkova P. K. Utrobin Yu. S. Kovalev A. V. Rogachev O. I. Ivankov S. A. Kutuzov D. V. Soloviov V. I. Gordeliy 《Physics of Particles and Nuclei Letters》2011,8(2):119-128
The results of experimental and computer-modeling investigations of neutron spectra and fluxes obtained with cold and thermal
moderators at the IBR-2 reactor (Joint Institute for Nuclear Research (JINR), Dubna) are presented. These studies are for
the YuMO small-angle neutron scattering (SANS) spectrometer (IBR-2 beamline 4). The neutron spectra have been measured for
two methane cold moderators for the standard configuration of the SANS instrument. The data from both moderators under different
conditions of their operation are compared. The ratio of experimentally determined neutron fluxes of cold and thermal moderators
is shown at different wavelengths. Monte Carlo simulations have been carried out to determine the spectra for cold-methane
and thermal moderators. The results of calculations of the ratio of neutron fluxes of cold and thermal moderators at different
wavelengths are demonstrated. In addition, the absorption of neutrons in the air gaps on the way from the moderator to the
investigated sample is presented. SANS with the protein apoferritin was done with both cold methane and a thermal moderator
and the data were compared. The prospects for the use of a cold moderator for a SANS spectrometer at IBR-2 are discussed.
The advantages of using the YuMO spectrometer with a thermal moderator with respect to the tested cold moderator are shown. 相似文献
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Tania Romero‐Morcillo Dr. Maksym Seredyuk Prof. Dr. M. Carmen Muñoz Prof. Dr. Jose A. Real 《Angewandte Chemie (International ed. in English)》2015,54(49):14777-14781
Herein, we report a way to achieve abrupt high‐spin to low‐spin transition with controllable transition temperature and hysteresis width, relying not on solid‐state cooperative interactions, but utilizing coherency between phase and spin transitions in neutral FeII meltable complexes. 相似文献
17.
Rotem Shemesh Maksym Krepker Diana Goldman Yael Danin‐Poleg Yechezkel Kashi Nadav Nitzan Anita Vaxman Ester Segal 《先进技术聚合物》2015,26(1):110-116
Active antimicrobial packaging is a promising form of active packaging that can kill or inhibit microorganism growth in order to maintain product quality and safety. One of the most common approaches is based on the release of volatile antimicrobial agents from the packaging material such as essential oils. Due to their highly volatile nature, the challenge is to preserve the essential oils during the high‐temperature melt processing of the polymer, while maintaining high antimicrobial activity for a desired shelf life. This study suggests a new approach in order to achieve this goal. Antimicrobial active films are developed based on low‐density polyethylene (LDPE), organo‐modified montmorillonite clays (MMT) and carvacrol (used as an essential oil model). In order to minimize carvacrol loss throughout the polymer compounding, a pre‐compounding step is developed in which clay/carvacrol hybrids are produced. The hybrids exhibit a significant increase in the d‐spacing of clay and enhanced thermal stability. The resulting LDPE/(clay/carvacrol) films exhibit superior and prolonged antibacterial activity against Escherichia coli and Listeria innocua, while polymer compounded with pure carvacrol loses the antibacterial properties within days. The films also present an excellent antifungal activity against Alternaria alternata, used as a model plant pathogenic fungus. Furthermore, infrared spectroscopy analysis of the LDPE/(clay/carvacrol) system displayed significantly higher carvacrol content in the film as well as a slower out‐diffusion of the carvacrol molecules in comparison to LDPE/carvacrol films. Thus, these new films have a high potential for antimicrobial food packaging applications due to their long‐lasting and broad‐spectrum antimicrobial efficacy. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
18.
Dr. Yuriy Rebets Dr. Elke Brötz Niko Manderscheid Dr. Bogdan Tokovenko Dr. Maksym Myronovskyi Prof. Dr. Peter Metz Dr. Lutz Petzke Dr. Andriy Luzhetskyy 《Angewandte Chemie (International ed. in English)》2015,54(7):2280-2284
Pamamycins are macrodiolides of polyketide origin with antibacterial activities. Their biosynthesis has been proposed to utilize succinate as a building block. However, the mechanism of succinate incorporation into a polyketide was unclear. Here, we report identification of a pamamycin biosynthesis gene cluster by aligning genomes of two pamamycin‐producing strains. This unique cluster contains polyketide synthase (PKS) genes encoding seven discrete ketosynthase (KS) enzymes and one acyl‐carrier protein (ACP)‐encoding gene. A cosmid containing the entire set of genes required for pamamycin biosynthesis was successfully expressed in a heterologous host. Genetic and biochemical studies allowed complete delineation of pamamycin biosynthesis. The pathway proceeds through 3‐oxoadipyl‐CoA, a key intermediate in the primary metabolism of the degradation of aromatic compounds. 3‐Oxoadipyl‐CoA could be used as an extender unit in polyketide assembly to facilitate the incorporation of succinate. 相似文献
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Nag A Kovalenko MV Lee JS Liu W Spokoyny B Talapin DV 《Journal of the American Chemical Society》2011,133(27):10612-10620
All-inorganic colloidal nanocrystals were synthesized by replacing organic capping ligands on chemically synthesized nanocrystals with metal-free inorganic ions such as S(2-), HS(-), Se(2-), HSe(-), Te(2-), HTe(-), TeS(3)(2-), OH(-) and NH(2)(-). These simple ligands adhered to the NC surface and provided colloidal stability in polar solvents. The versatility of such ligand exchange has been demonstrated for various semiconductor and metal nanocrystals of different size and shape. We showed that the key aspects of Pearson's hard and soft acids and bases (HSAB) principle, originally developed for metal coordination compounds, can be applied to the bonding of molecular species to the nanocrystal surface. The use of small inorganic ligands instead of traditional ligands with long hydrocarbon tails facilitated the charge transport between individual nanocrystals and opened up interesting opportunities for device integration of colloidal nanostructures. 相似文献