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71.
Daniel Hewitt Tom Pope Misbah Sarwar Alessandro Turrina Ben Slater 《Chemical science》2022,13(44):13178
The production of widely used polymers such as polyester currently relies upon the chemical separation of and transformation of xylene isomers. The least valuable but most prevalent isomer is meta-xylene which can be selectively transformed into the more useful and expensive para-xylene isomer using a zeolite catalyst but at a high energy cost. In this work, high-throughput screening of existing and hypothetical zeolite databases containing more than two million structures was performed, using a combination of classical simulation and deep neural network methods to identify promising materials for selective adsorption of meta-xylene. Novel anomaly detection techniques were applied to the heavily biased classification task of identifying structures with a selectivity greater than that of the best performing existing zeolite, ZSM-5 (MFI topology). Eight hypothetical zeolite topologies are found to be several orders of magnitude more selective towards meta-xylene than ZSM-5 which may provide an impetus for synthetic efforts to realise these promising materials. Moreover, the leading hypothetical frameworks identified from the screening procedure require a markedly lower operating temperature to achieve the diffusion seen in existing materials, suggesting significant energetic savings if the frameworks can be realised.A combination of machine learning and high throughput simulation has identified several potential zeolite structures that appear to outperform the leading commercially used material and explained the key factors for high selectivity. 相似文献
72.
The suitability of high-resolution gas chromatography (HGRC) for the analysis of the raffinose family oligosaccharides (raffinose, stachyose, verbascose) was investigated. Aqueous methanol (80%) extracts of pea flour were dried and derivatized with either trimethylimidazole or N-methyl-bis(trifluoroacetamide). Separation of the sugar derivatives was achieved utilizing a 10-m DB5-60W capillary column. The effects of carrier gas (He) flow-rate and split ratio on resolution and reproducibility were studied. HRGC analysis was characterized by excellent resolution and satisfactory reproducibility, and proved to be a rapid, sensitive method for quantitation of oligosaccharides in pea flours. 相似文献
73.
74.
Nineteen elementary and 5 middle school in-service teachers served as regional lead teachers to provide 13 two- and four-day workshops for 235 in-service teachers. The lead teachers attended 100 hours of inservice training on national science/math reform curricula, cognitive theory, pedagogical strategies for enhancing problem solving, and authentic assessment procedures. The lead teachers then selected $30,000 worth of instructional materials for use in their classrooms. Subsequently, they developed four hands-on-manipulative-based workshops through extensive use of video-teleconferencing technology. The lead teachers strongly believe that this extensive project has made a permanent positive impact on the quality and quantity of integrated science and math instruction in Kansas. 相似文献
75.
Shuneize Slater Pradeep B. Lasonkar Saqlain Haider Moneerah J. Alqahtani Amar G. Chittiboyina Ikhlas A. Khan 《Tetrahedron letters》2018,59(9):807-810
Novel, functionalized octahydrochromane derivatives were synthesized in a single step via the Prins reaction. Enantiomerically pure (+)-isopulegol was reacted with benzaldehyde to stereoselectively yield the corresponding octahydro-2H-chromen-4-ol derivative containing five stereocenters. A total of 10 compounds were synthesized by altering the enantiomer of isopulegol and the substituted benzaldehyde, and the resulting enantiopure octahydrochromanes were screened in vitro against the cannabinoid receptor isoforms CB1 and CB2. Compounds containing an olefin at the C4 position [(+)-3c, (?)-3c, (?)-7c, (?)-9c and (?)-11c] of the octahydrochromane scaffold were found to exhibit reasonable displacement of [3H] CP55,940 from the CB receptors, whereas the corresponding hydroxy analogs [(+)-3a, (+)-3b, (?)-3a, (?)-3b and (+)-5a] had very little or no effect. 相似文献
76.
Dr. Dong Heon Nam Dr. Jenny Z. Zhang Virgil Andrei Dr. Nikolay Kornienko Dr. Nina Heidary Andreas Wagner Kenichi Nakanishi Katarzyna P. Sokol Barnaby Slater Dr. Ingo Zebger Prof. Stephan Hofmann Dr. Juan C. Fontecilla‐Camps Prof. Chan Beum Park Prof. Erwin Reisner 《Angewandte Chemie (International ed. in English)》2018,57(33):10595-10599
Hydrogenases (H2ases) are benchmark electrocatalysts for H2 production, both in biology and (photo)catalysis in vitro. We report the tailoring of a p‐type Si photocathode for optimal loading and wiring of H2ase through the introduction of a hierarchical inverse opal (IO) TiO2 interlayer. This proton‐reducing Si|IO‐TiO2|H2ase photocathode is capable of driving overall water splitting in combination with a photoanode. We demonstrate unassisted (bias‐free) water splitting by wiring Si|IO‐TiO2|H2ase to a modified BiVO4 photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation. Connecting the Si|IO‐TiO2|H2ase to a photosystem II (PSII) photoanode provides proof of concept for an engineered Z‐scheme that replaces the non‐complementary, natural light absorber photosystem I with a complementary abiotic silicon photocathode. 相似文献
77.
78.
Sandford G Slater R Yufit DS Howard JA Vong A 《The Journal of organic chemistry》2005,70(18):7208-7216
[reaction: see text] Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds have been synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give poly-substituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of previously inaccessible poly-substituted pyridopyrazine derivatives. This general approach has special relevance to the development of new chemical entities for the life science industries and particularly in the drug discovery arena, in which low molecular weight, polyfunctional heterocyclic derivatives are playing an increasingly important role. 相似文献
79.
In this communication we demonstrate high temperature proton conduction in the phase La(1-x)Ba(1+x)GaO(4-x/2), with conductivities significantly higher than reported for other phases containing tetrahedral ions, such as doped LaPO4. 相似文献
80.
We study the mobility of short ssDNA fragments (approximately 30-500 bases) separated by capillary electrophoresis in entangled polymer solutions. Although this corresponds to what is commonly called the Ogston regime, the corresponding sieving concept has never been defined properly nor tested quantitatively. We consider three formulas that have been suggested to fit data in this range of ssDNA sizes, and we discuss how their free parameters are related to actual physical parameters. We test these formulas with new data obtained in our laboratory using a commercial poly-N,N-dimethylacrylamide sieving matrix. Our results show that all three formulas provide decent fits. However, the traditional Ogston equation produces fitting parameters that appear to lack physical meaning. Surprisingly, all three approaches predict that the effective pore size and fiber radius are almost equal. This is the first step towards the development of a systematic approach to optimizing sequencing systems for this size range. 相似文献