K3ReH6 – Synthesis, Structure, and Magnetic Properties K3ReH6 and K3ReD6 were synthesized by the reaction of potassium hydride (deuteride) with rhenium powder under a hydrogen pressure between 3000–3500 bar at 850 K. X-ray investigations on powdered samples and elastic neutron diffraction experiments on the deuterated compound at the triple axis spectrometer TAS 1 in the temperature range 5–600 K led to the atomic arrangement, which corresponds to that of the cryolite with [ReH6]3–-octahedra as characteristic units. Magnetic susceptibility measurements in the temperature range from 3.5 K and room temperature revealed a weak temperature independent paramagnetism. Quantum mechanical calculations confirm these facts and show in detail that the large value of the spin-orbit coupling parameter is essential for the magnetic behaviour. 相似文献
High Pressure Synthesis and Crystal Structure of YbH2.67 Ytterbiumhydrides can be synthesized by reaction of ytterbium metal in hydrogen atmosphere above 600 K. The experiments were carried out in the pressure range from 200 to 3200 bar. X‐ray investigations on powdered samples and elastic neutron diffraction experiments on deuterated compounds led to a complete structure determination. YbH2.67 is obtained at reaction pressures of 200, 1400 und 3200 bar. In contrast to reports in literature the deuterides crystallize with trigonal symmetry (P3¯1m, a = 6.344(1)Å, c = 9.002(1)Å, Z = 9) and not in the cubic crystal system. The composition YbD2.67 was additionally checked by chemical analysis. The crystal structure can be described as a close packing of ytterbium atoms (stacking sequence …ABC…) in which all tetrahedral holes and 2/3 of the octahedral holes are occupied in an ordered manner by hydrogen. Magnetic susceptibility measurements are in agreement with literature data. 相似文献
Polyhydroxyalkanoates (PHAs) are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials such as saccharides, alcohols and low-molecular-weight fatty acids. They are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. By keeping closed the cycle of production and re-use, PHAs can enable at least part of the polymer-producing industry to switch from ecologically harmful end-of-the-pipe production methods towards sounder technologies. Up to now such polyesters have been produced biotechnologically from refined raw materials (e.g. glucose and sodium propionate), but they can as well be produced much cheaper from agricultural waste materials (e.g. molasses, maltose, glycerol phase from biodiesel production, whey), as long as these materials have a known composition and are available in appropriate quantities. Yield factors and specific rates for growth and PHA accumulation are shown for 3 strains of Alcaligenes latus for different agricultural waste carbon sources. 相似文献
The phase diagram of a series of poly(1,2‐octylene oxide)–poly(ethylene oxide) (POO–PEO) diblock copolymers is determined by small‐angle X‐ray scattering. The Flory–Huggins interaction parameter was measured by small‐angle neutron scattering. The phase diagram is highly asymmetric due to large conformational asymmetry that results from the hexyl side chains in the POO block. Non‐lamellar phases (hexagonal and gyroid) are observed near fPEO = 0.5, and the lamellar phase is observed for fPEO ≥ 0.5.
The compositions and the multi phase structures of bio‐nanocomposite hydrogels made from silicate cross‐linked PEO and chitosan are related to some of their physical and biological properties. The gels are injectable and self‐healing because the cross‐linking is physical and reversible under deformation. The presence of chitosan aggregates affects the viscoelastic properties and reinforces the hydrogel network. The chitosan adds advantageous properties to the hydrogel such as enhanced cell spreading and adhesion. In vitro biocompatibility data indicate that NIH 3T3 fibroblasts grow and proliferate on the bio‐nanocomposite hydrogel as well as on hydrogel films.
We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the?loop. 相似文献
The HYDE scoring function consistently describes hydrogen bonding, the hydrophobic effect and desolvation. It relies on HYdration and DEsolvation terms which are calibrated using octanol/water partition coefficients of small molecules. We do not use affinity data for calibration, therefore HYDE is generally applicable to all protein targets. HYDE reflects the Gibbs free energy of binding while only considering the essential interactions of protein-ligand complexes. The greatest benefit of HYDE is that it yields a very intuitive atom-based score, which can be mapped onto the ligand and protein atoms. This allows the direct visualization of the score and consequently facilitates analysis of protein-ligand complexes during the lead optimization process. In this study, we validated our new scoring function by applying it in large-scale docking experiments. We could successfully predict the correct binding mode in 93% of complexes in redocking calculations on the Astex diverse set, while our performance in virtual screening experiments using the DUD dataset showed significant enrichment values with a mean AUC of 0.77 across all protein targets with little or no structural defects. As part of these studies, we also carried out a very detailed analysis of the data that revealed interesting pitfalls, which we highlight here and which should be addressed in future benchmark datasets. 相似文献
Summary: The analysis of the influence of ionic liquids (ILs) in polymer synthesis as an alternative for common organic solvents is still an active field of research. 1 Using ILs as solvents for free radical polymerizations implies a significant increase in polymerization rates and molecular weights which can be observed. In this work we examined the copolymerization behaviour of styrene (S) and methyl methacrylate (MMA), glycidyl methacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA) with acrylonitrile (AN) in 1-etyhl-3-methylimidazolium ethylsulfate ([EMIM]EtSO4). ILs are liquids with comparable high polarities and viscosities. These two characteristic properties are strongly correlated with the rate coefficients of propagation kp and termination kt. 2 - 4 The rate constant of termination kt decreases when the IL concentration and therefore the viscosity of the reaction mixture is increased, whereas the propagation rate coefficient kp increases with increasing IL content. The viscosity of the IL can be varied by either working with mixtures of IL with conventional organic solvents – here the IL [EMIM]EtSO4 was mixed with DMF – or by variation of the temperature. The influence of the viscosity of the IL ([EMIM]EtSO4) on polymerization kinetics of methyl methacrylate (MMA) and styrene/acrylonitrile (S/AN) was investigated. 相似文献