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21.
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Richard Böser Lars Denker Dr. René Frank 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10575-10579
Benzyl-substituted boronates and borates are widely employed as mild sources in radical or anionic transfer reactions of benzyl entities. In this process the B−C bond to the benzyl moiety is essentially ruptured. In contrast, reactions with retention of the B−C bond are poorly investigated although several other reactive sites in benzyl–boron systems are clearly inherent. In this respect, the novel reactivity of the representative borane adduct IiPr−BH2Bn [IiPr=:C{N(iPr)CH}2, Bn=CH2C6H5] is demonstrated. Dihalogenation of the BH2 entity is observed with BCl3 and BBr3, whereas BI3 either affords IiPr−BHI2 or proceeds with borylation of the aromatic phenyl ring to give a hydride-bridged bisborylated species. The photochemical mono- and dihalogenation of the benzylic CH2 group was demonstrated with elemental bromine Br2. The brominated product IiPr−BBr2−CHBr−C6H5 was borylated at the benzylic carbon atom in an umpolung event with BI3 to afford the zwitterion IiPr−BI−CH(BI3)−C6H5. 相似文献
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High‐performance alternating current electroluminescent layers solution blended with mechanically and electrically robust nonradiating polymers 下载免费PDF全文
24.
Ziyi Yu Jing Zhang Roger J. Coulston Richard M. Parker Frank Biedermann Xin Liu Oren A. Scherman Chris Abell 《Chemical science》2015,6(8):4929-4933
Host–guest assembly in droplet-based microfluidics opens a new avenue for fabricating supramolecular hydrogel microcapsules with high monodispersity and controlled functionality. In this paper, we demonstrate a single emulsion microdroplet platform to prepare microcapsules with supramolecular hydrogel skins from host molecule cucurbit[8]uril and guest polymer anthracene-functionalized hydroxyethyl cellulose. In contrast to construction of microcapsules from a droplet-in-droplet double emulsion, here the electrostatic attraction between charged polymer and surfactant facilitates formation of defined supramolecular hydrogel skins in a single emulsion. Furthermore, by taking advantage of dynamic interactions and the tunable cross-linked supramolecular hydrogel network, it is possible to prepare microcapsules with triggered and UV-controlled molecular permeability. These could be potentially used in a delivery system for e.g. agrochemicals, nutraceuticals or cosmetics. 相似文献
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Quantification of myo‐inositol, 1,5‐anhydro‐ D‐sorbitol,and D‐chiro‐inositol using high‐performance liquid chromatography with electrochemical detection in very small volume clinical samples 下载免费PDF全文
Karen J. Schimpf Claudia C. Meek Richard D. Leff Dale L. Phelps Daniel J. Schmitz Christopher T. Cordle 《Biomedical chromatography : BMC》2015,29(11):1629-1636
Inositol is a six‐carbon sugar alcohol and is one of nine biologically significant isomers of hexahydroxycyclohexane. Myo‐inositol is the primary biologically active form and is present in higher concentrations in the fetus and newborn than in adults. It is currently being examined for the prevention of retinopathy of prematurity in newborn preterm infants. A robust method for quantifying myo‐inositol (MI), D ‐chiro‐inositol (DCI) and 1,5‐anhydro‐ D ‐sorbitol (ADS) in very small‐volume (25 μL) urine, blood serum and/or plasma samples was developed. Using a multiple‐column, multiple mobile phase liquid chromatographic system with electrochemical detection, the method was validated with respect to (a) selectivity, (b) accuracy/recovery, (c) precision/reproducibility, (d) sensitivity, (e) stability and (f) ruggedness. The standard curve was linear and ranged from 0.5 to 30 mg/L for each of the three analytes. Above‐mentioned performance measures were within acceptable limits described in the Food and Drug Administration's Guidance for Industry: Bioanalytical Method Validation. The method was validated using blood serum and plasma collected using four common anticoagulants, and also by quantifying the accuracy and sensitivity of MI measured in simulated urine samples recovered from preterm infant diaper systems. The method performs satisfactorily measuring the three most common inositol isomers on 25 μL clinical samples of serum, plasma, milk, and/or urine. Similar performance is seen testing larger volume samples of infant formulas and infant formula ingredients. MI, ADS and DCI may be accurately tested in urine samples collected from five different preterm infant diapers if the urine volume is greater than 2–5 mL. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
28.
Crosslinked poly(ethylene oxide) containing siloxanes fabricated through thiol‐ene photochemistry 下载免费PDF全文
Victor A. Kusuma Elliot A. Roth William P. Clafshenkel Steven S. Klara Xu Zhou Surendar R. Venna Erik Albenze David R. Luebke Meagan S. Mauter Richard R. Koepsel Alan J. Russell David Hopkinson Hunaid B. Nulwala 《Journal of polymer science. Part A, Polymer chemistry》2015,53(13):1548-1557
Homogenous amphiphilic crosslinked polymer films comprising of poly(ethylene oxide) and polysiloxane were synthesized utilizing thiol‐ene “ click ” photochemistry. A systematic variation in polymer composition was Carried out to obtain high quality films with varied amount of siloxane and poly(ethylene oxide). These films showed improved gas separation performance with high gas permeabilities with good CO2/N2 selectivity. Furthermore, the resulting films were also tested for its biocompatibility, as a carrier media which allow human adult mesenchymal stem cells to retain their capacity for osteoblastic differentiation after transplantation. The obtained crosslinked films were characterized using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, FTIR, Raman‐IR , and small angle X‐ray scattering. The synthesis ease and commercial availability of the starting materials suggests that these new crosslinked polymer networks could find applications in wide range of applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1548–1557 相似文献
29.
A rapid and effective preparative procedure has been evaluated for the accurate determination of low-energy (40–200 keV) gamma-emitting radionuclides (210Pb, 234Th, 226Ra, 235U) in uranium ores and uranium ore concentrates (UOCs) using high-resolution gamma ray spectrometry. The measurement of low-energy gamma photons is complicated in heterogeneous samples containing high-density mineral phases and in such situations activity concentrations will be underestimated. This is because attenuation corrections, calculated based on sample mean density, do not properly correct where dense grains are dispersed within a less dense matrix (analogous to a nugget effect). The current method overcomes these problems using a lithium tetraborate fusion that readily dissolves all components including high-density, self-attenuating minerals/compounds. This is the ideal method for dissolving complex, non-volatile components in soils, rocks, mineral concentrates, and other materials where density reduction is required. Lithium borate fusion avoids the need for theoretical efficiency corrections or measurement of matrix matched calibration standards. The resulting homogeneous quenched glass produced can be quickly dissolved in nitric acid producing low-density solutions that can be counted by gamma spectrometry. The effectiveness of the technique is demonstrated using uranium-bearing Certified Reference Materials and provides accurate activity concentration determinations compared to the underestimated activity concentrations derived from direct measurements of a bulk sample. The procedure offers an effective solution for initial nuclear forensic studies where complex refractory minerals or matrices exist. It is also significantly faster, safer and simpler than alternative approaches. 相似文献
30.
Corina Andronescu Justus Masa Richard D. Tilley John J. Gooding Wolfgang Schuhmann 《Current Opinion in Electrochemistry》2021
The complex interplay of restricted mass transport leading to local accumulation or depletion of educts, intermediates, products, counterions and co-ions influences the reactions at the active sites of electrocatalysts when electrodes are rough, three-dimensionally mesoporous or nanoporous. This influence is important with regard to activity, and even more to selectivity, of electrocatalytic reactions. The underlying principles are discussed based on the growing awareness of these considerations over recent years. 相似文献