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91.
Peter C. Ho Justin Lomax Valerie Tomassetti Dr. James F. Britten Dr. Ignacio Vargas-Baca 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10849-10853
Chlorination of 3-methyl-5-phenyl-1,2-tellurazole-2-oxide yielded the λ4Te dichloro derivative. Its crystal structure demonstrates that the heterocycle retains its ability to autoassociate by chalcogen bonding (ChB) forming macrocyclic tetramers. The corresponding Te⋅⋅⋅O ChB distances are 2.062 Å, the shortest observed to date in aggregates of this type. DFT−D3 calculations indicate that while the halogenated molecule is stronger as a ChB donor it also is a weaker ChB acceptor; the overall effect is that the ChBs in the chlorinated homotetramer are not significantly stronger. However, partial halogenation or scrambling selectively yield the 2 : 2 heterotetramer with alternating λ4Te and λ2Te centers, which calculations identified as the thermodynamically preferred arrangement. 相似文献
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Dr. Michael L. Tarlton Dr. Xiaojuan Yu Robert J. Ward Dr. Steven P. Kelley Dr. Jochen Autschbach Dr. Justin R. Walensky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(58):14396-14400
The coordination of tBuNC and CO with the diarsenido complexes (C5Me5)2An(η2-As2Mes2), An=Th, U, has been investigated. For the first time, a comparison between isostructural complexes of ThIV and UIV has been possible with CO; density functional calculations indicated an appreciable amount of π backbonding that originates from charge transfer from an actinide-arsenic sigma bond. The calculated CO stretching frequencies in the ThIV and UIV diarsenido complexes are consistent with the experimental measurements, both show large shifts to lower frequency. We demonstrate that the π backbonding is crucial to explaining the red shifts of CO frequency upon AnIV complex formation. Interestingly, this interaction essentially correlates to the parallel orientation of π*(C−O) orbitals relative to the An−As bond. 相似文献
95.
In large distribution systems, distribution centers (DC) deliver some merchandize to their retail stores in size-specific packages, also called ship-packs. These ship-packs include cases (e.g., cartons containing 24 or 48 units), inners (packages of 6 or 8 units) or eaches (individual units). For each Stock Keeping Unit (SKU), a retailer can decide which of these ship-pack options to use when replenishing its retail stores. Working with a major US retailer, we have developed a cost model that balances DC handling costs, store handling costs and inventory-related costs at both the DC and the stores, and therefore can help to determine the optimum warehouse ship-pack for each SKU. We implement our model for a sample of 529 SKUs, and show that by changing ship-pack size for about 30 SKUs, the retailer can reduce its total cost by 0.3% - 0.4%. Interestingly, we find that most of the cost savings occurs at the DC level. 相似文献
96.
Professor George W. Gray 《Liquid crystals》2013,40(5):751-752
Abstract Optical microscopy in mixtures of di-octylazoxybenzene (8AB) and di-nonylazoxybenzene (9AB) reveals that a smectic A-nematic-isotropic triple point occurs at 71·5±0·5°C and 38±2wt% 8AB. Although this concentration induced triple point is different from the pressure induced triple point known to exist in pure 9AB at elevated pressure, analysis of the data from both the mixing and pressure experiments reveals that the phase transition surfaces in temperature-pressure-concentration space for this system are nearly planar. 相似文献
97.
Molecular and morphological characterization of midblock‐sulfonated styrenic triblock copolymers
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Kenneth P. Mineart Justin J. Ryan Byeongdu Lee Steven D. Smith Richard J. Spontak 《Journal of Polymer Science.Polymer Physics》2017,55(6):490-497
Midblock‐sulfonated triblock copolymers afford a desirable opportunity to generate network‐forming amphiphilic materials that are suitable for use in a wide range of emerging technologies as fuel‐cell, water‐desalination, ion‐exchange, photovoltaic, or electroactive membranes. Employing a previously reported synthetic strategy wherein poly(p‐tert‐butylstyrene) remains unreactive, we have selectively sulfonated the styrenic midblock of a poly(p‐tert‐butylstyrene‐b‐styrene‐b‐p‐tert‐butylstyrene) (TST) triblock copolymer to different extents. Comparison of the resulting sulfonated copolymers with results from our prior study provides favorable quantitative agreement and suggests that a shortened reaction time is advantageous. An ongoing challenge regarding the morphological development of charged block copolymers is the competition between microphase separation of the incompatible blocks and physical cross‐linking of ionic clusters, with the latter often hindering the former. Here, we expose the sulfonated TST copolymers to solvent‐vapor annealing to promote nanostructural refinement. The effect of such annealing on morphological characteristics, as well as on molecular free volume, is explored. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 490–497 相似文献
98.
Hong Zhang Zuoquan Wang Ion Ghiviriga Girinath G. Pillai Farukh Jabeen Justin A. Arami Wenfeng Zhou Peter J. Steel C. Dennis Hall Alan R. Katritzky 《Tetrahedron letters》2017,58(12):1079-1085
Synthesis, characterization and energetic properties of novel, nitrogen-rich 1-methyl-1,2,4-triazolium N-aryl/N-pyridinyl ylids 3a–m are reported. 相似文献
99.
Justin L. Poklis Maciej M. Gonek Carl E. Wolf Hamid I. Akbarali William L. Dewey 《Biomedical chromatography : BMC》2019,33(4)
Carbenoxolone is a derivative of glycyrrhetinic acid found in the root of Glycyrrhiza glabra, colloquially known as licorice. It has been used as a treatment for peptic and oral ulcers. In recent years, carbenoxolone has been utilized in basic research for its ability to block gap junctional communication. Better understanding the distribution of carbenoxolone after systemic administration can lead to a better understanding of its potential sites of action. Presented is an ultra high‐performance liquid chromatography tandem mass spectrometer (UHPLC–MS/MS) method for the identification and quantification of carbenoxolone in mouse blood and brain tissue. Twenty mice were injected intraperitoneally with 25 mg/kg carbenoxolone and brain tissue and blood were collected for analysis. Blood concentrations (mean ± SD) at 15, 30, 60 and 120 min were determined to be (n = 5) 5394 ± 778, 2636 ± 836, 1564 ± 541 and 846 ± 252 ng/mL, respectively. Brain concentrations (mean ± SD) at 15, 30, 60 and 120 mins were determined to be (n = 5) 171 ± 62, 102 ± 35, 55 ± 10 and 27 ± 9 ng/g, respectively. The analysis of these specimens at the four different time points resulted in blood and brain half‐lives in mice of ~43 and 41 min, respectively. The UHPLC–MS/MS method was determined to be sensitive and robust for quantification of carbenoxolone. 相似文献
100.
Abstract Deuterium quadrupole echo spectroscopy has been used to probe the orientational behaviour and dynamics of CDCl3 molecules in ethylcellulose/chloroform chiral nematic phases. The 2H spectra of both left-handed and right-handed mesophases, formed by ethylcellulose with degrees of substitution of 2·3 and 3·0 respectively, were examined as functions of temperature and concentration. The observed quadrupolar splittings are relatively large and the magnitudes of the order parameters of the solvent molecules show little correlation with the handedness of the chiral phases. However, the 2H line shapes of these two types of chiral phase exhibit rather different temperature dependences. Spectral simulations show that the observed line shapes and their temperature variations are mainly determined by diffusion of CDCl3 molecules along the pitch axis. The effects of centrifugation on the 2H spectra are also described. 相似文献