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431.
Substitution of Two Active‐Site Residues Alters C9‐Hydroxylation in a Class II Diterpene Synthase
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Dr. Sibongile Mafu Emil Fischer Dr. J. Bennett Addison Isabel Riberio Barbosana Dr. Philipp Zerbe 《Chembiochem : a European journal of chemical biology》2016,17(24):2304-2307
Diterpenes form a vast and diverse class of natural products of both ecological and economic importance. Class II diterpene synthase (diTPS) enzymes control the committed biosynthetic reactions underlying diterpene chemical diversity. Homology modelling with site‐directed mutagenesis identified two active‐site residues in the horehound (Marrubium vulgare) class II diTPS peregrinol diphosphate synthase (MvCPS1); residue substitutions abolished the unique MvCPS1‐catalysed water‐capture reaction at C9 and redirected enzyme activity toward formation of an alternative product, halima‐5(10),13‐dienyl diphosphate. These findings contributed new insight into the steric interactions that govern diTPS‐catalysed regiospecific oxygenation reactions and highlight the feasibility of diTPS engineering to provide a broader spectrum of bioactive diterpene natural products. 相似文献
432.
Heavy metal interactions with anaerobically disgested sludges have been studied using acid elution and functional group blocking techniques. The release of heavy metals from anaerobically digested sludges was pH dependent. The results have suggested that the mechanism of binding involves weakly acidic functional groups. When the sludges were methylated using dimethyl sulfate, the capacities for zinc, copper, nickel and cadmium were reduced. 相似文献
433.
434.
In this paper we construct extrapolated multirate discretization methods that allows one to efficiently solve problems that have components with different dynamics. This approach is suited for the time integration of multiscale ordinary and partial differential equations and provides highly accurate discretizations. We analyze the linear stability properties of the multirate explicit and linearly implicit extrapolated methods. Numerical results with multiscale ODEs illustrate the theoretical findings. 相似文献
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437.
Dongguen Shin Fengshuo Zu Edgar R. Nandayapa Lennart Frohloff Emily Albert Emil J. W. List-Kratochvil Norbert Koch 《Advanced functional materials》2023,33(2):2208980
The success of using 2D Ruddlesden-Popper metal halide perovskites (MHPs) in optoelectronic devices has ignited great interest as means for energy level tuning at the interface with 3D MHPs. Inter alia, the application of 2D phenylethylammonium lead quaternary iodide (PEA2PbI4)/3D MHPs interfaces has improved various optoelectronic devices, where a staggered type-II energy level alignment is often assumed. However, a type-II heterojunction seems to contradict the enhanced photoluminescence observed for 2D PEA2PbI4/3D MHP interfaces, which raises fundamental questions about the electronic properties of such junctions. In this study, using direct and inverse photoelectron spectroscopy, it is revealed that a straddling type-I energy level alignment is present at 2D PEA2PbI4/3D methylammonium lead triiodide (MAPbI3) interfaces, thus explaining that the photoluminescence enhancement of the 3D perovskite is induced by energy transfer from the 2D perovskite. These results provide a reliable fundamental understanding of the electronic properties at the investigated 2D/3D MHP interfaces and suggest careful (re)consideration of the electronic properties of other 2D/3D MHP heterostructures. 相似文献
438.
Jaroslav Stehlí
ek Franti
ek Lednický Josef Baldrian Jan ebenda Emil Neuhusl 《Polymer Engineering and Science》1991,31(6):422-431
The liquid rubbers Hycar ATBN and HTBN were used in the preparation of poly(ε-caprolactam)—poly(butadiene-co-acrylonitrile) block copolymers intended for reaction injection molding by the anionic polymerization of ε-caprolactam. The conversion of Hycar end groups to polymerization growth centers and the conditions of polymerization influence the crystallization, morphology, and mechanical properties of the product through its molecular structure. The contribution of individual reactions to this molecular structure is discussed. 相似文献
439.
2-(o-chlorophenyl)-4-methylene-1,3-dioxolane was synthesized and polymerized in presence of AIBN or by use of benzoin methyl
ether as photosensitizer. Based on the analysis of the resulting polymers, a polymerization mechanism was proposed. 相似文献
440.
Production of petrol from coal and natural gas . This article assumes an adequate knowledge of the Fischer-Tropsch process in its original form and as its modern variant, the Synthol process, and adopts the view that coal hydrogenation will only become implementable on an industrial scale in the early 1990. In detail, it considers the integration of the Mobil MTG process in the proven area of methanol production; operation of pilot plant has shown that this process is indeed suitable for industrial scale operation. The production of methanol from natural gas and coal is discussed, as is the subsequent conversion of methanol to petrol; emphasis is placed on the best possible integration of all process plant. Apart from the conventional steam reforming route for methanol production from natural gas, the alternative approach of combing a steam reforming plant with an autothermal cleavage step is also considered; the latter leads to a significant increase in efficiency and a reduction in investment costs. It is also shown for coal as raw material that simultaneous generation of petrol and SNG has considerable advantages of a thermal and financial nature. The principal process steps are described after the manner of keywords and the product costs are presented as functions of the various raw material costs. 相似文献