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71.
Dr. J. Grant Hill Xiaojun Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3620-3628
Benchmark quality geometries and interaction energies for the prereactive halogen‐bonded complexes of dihalogens and ammonia, including hypothetical astatine containing dihalogens, have been produced via explicitly correlated coupled cluster methods. The application of local electron correlation partitioning reveals dispersion, electrostatics and ionic substitutions all contribute significantly to the interaction energy, with a linear relationship between the ionic substitutions and the degree of charge transfer. Potential energy curves for H3N???ClF show that as the relative orientations of the two subunits are manipulated appreciable interactions can be found at considerably angular displaced geometries, signifying lower directionality in halogen bonding than previously supposed. 相似文献
72.
Manool is converted into ring-B-nor analogues of commercially important perfumery compounds via a novel ring-B-nor intermediate methylene ketone 9. Compound 9 is synthesised via the formation of an exocyclic bromonium ion and the concomitant ring contraction of the B-ring of a diterpene skeleton derived from manool. Oxidation and base treatment of the ring-contracted product result in dehydrohalogenation and decarboxylation to afford methylene ketone compound 9, which is then converted to ring-B-nor analogues of Ambrox® and amberketal. 相似文献
73.
Harper JK Strohmeier M Grant DM 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,189(1):20-31
The (1)H-(13)C solid-state NMR heteronuclear correlation (HETCOR) experiment is demonstrated to provide shift assignments in certain powders that have two or more structurally independent molecules in the unit cell (i.e. multiple molecules per asymmetric unit). Although this class of solids is often difficult to characterize using other methods, HETCOR provides both the conventional assignment of shifts to molecular positions and associates many resonances with specific molecules in the asymmetric unit. Such assignments facilitate conformational characterization of the individual molecules of the asymmetric unit and the first such characterization solely from solid-state NMR data is described. HETCOR offers advantages in sensitivity over prior methods that assign resonances in the asymmetric unit by (13)C-(13)C correlations and therefore allows shorter average analysis times in natural abundance materials. The (1)H-(13)C analysis is demonstrated first on materials with known shift assignments from INADEQUATE data (santonin and Ca(OAc)(2) phase I) to verify the technique and subsequently is extended to a pair of unknown solids: (+)-catechin and Ca(OAc)(2) phase II. Sufficient sensitivity and resolution is achieved in the spectra to provide assignments to one of the specific molecules of the asymmetric unit at over 54% of the sites. 相似文献
74.
Grant Korensky Xinye Chen Mengdi Bao Abbi Miller Blanca Lapizco-Encinas Myeongkee Park Ke Du 《Electrophoresis》2021,42(1-2):95-102
A planar, transparent, and adaptable nanosieve device is developed for efficient microalgae/bacteria separation. In the proposed method, a sacrificial layer is applied with dual photolithography patterning to achieve a 1D channel with a very low aspect ratio (1:10 000). A microalgae/bacteria mixture is then introduced into the deformable PDMS nanochannel. The hydrodynamic deformation of the nanochannel is regulated to allow the bacteria cells to pass through while leaving the microalgae cells trapped in the device. At a flow rate of 4 μL/min, the supernatant collected from the device is indistinguishable from a control solution, indicating that nearly all the microalgae cells are trapped in the device. Additionally, this device is capable of single cell auto-fluorescence tracking. These microalgae cells demonstrate minimal photobleaching over 250 s laser exposure and could be used to monitor hazardous compounds in the sample with a continuous flow. This method will be valuable to purify microalgae samples containing contaminations and study single-cell heterogeneity. 相似文献
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Abstract Metallic glasses of Fe80B20 and Fe80P13C7 prepared by rapid quenching have been implanted with 40 keV Ar+, P+ and B+ ions at doses up to 2.1016 ions cm?2 at 273 K. The structure of the glasses was examined by X-ray diffraction. Crystallites of α-Fe and Fe3B, present in F80B20 samples, either become highly defective or are amorphised. Implantation also produces structural changes in the amorphous Fe80B20 (a-Fe80B20) phase as revealed by changes in the width β of the principal diffraction halo. Both disordering and relaxation effects are observed, dependent on the initial degree of order within the a-Fe80B20 phase before irradiation. Implantation of F80p13C7 results in an increase in the content of γ-Fe and Fe3P crystallites, already present before irradiation, and in the nucleation of α-Fe. 相似文献
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