Preparation of W1/O/W2 emulsion to limit the diffusion of Fe3+ in the Fricke gel 3D dosimeter

The irradiation of tumors in radiotherapy requires accurate 3D dosimetry. The Fricke 3D dosimeters, which were considered to be high potential of application in 3D dosimetry, suffer from a reduced temporal integrity of dose distribution caused by Fe³⁺ ions diffusion. To overcome the drawback, we firstly synthesized a kind of amphiphilic molecules with critical micelle concentration of 0.45 g/L and hydrophile‐lipophile balance value of 10, then prepared multiple emulsions by self‐assembling those molecules in Fricke solution under liquid paraffin, and finally obtained Fricke hydrogel embedded with the multiple emulsions. The diffusion coefficient of Fe³⁺ ions in the embedded Fricke hydrogel was measured to be 0.17 mm²/h. The hydrogel dosimeter exhibits considerable potential for use in dose verification applications.     

靶向抗肿瘤药N-(N’-苄氧羰基甘氨酰脯氨酰)丙卡巴肼(Z-GP-Pcb)的环境友好合成及其透过血脑屏障活性评价

利用靶向策略设计了抗肿瘤药物N-(N’-苄氧羰基甘氨酰脯氨酰)丙卡巴肼(Z-GP-Pcb),发展了3步法合成丙卡巴肼(Pcb).首先以4-甲基苯甲醛为原料,经二溴异氰脲酸(DBI)转化为N-异丙基-4-甲基苯酰胺.该化合物经2-碘酰基苯甲酸(IBX)直接氧化为N-异丙基-4-甲酰基苯酰胺,随后还原胺化得Pcb.最后与N-苄氧羰基甘氨酰脯氨酸缩合得Z-GP-Pcb,总收率49.9%.另外,本研究还建立了体外平行人造膜渗透测血脑屏障(PAMPA-BBB)方法评价Z-GP-Pcb透过血脑屏障(BBB)活性,发现其透膜常数(Pe)为(19.22±4.25)×10^-6cm·s^-1,大于母药Pcb[(11.14±1.34))×10^-6cm·s^-1],具有较高的透过BBB活性.     

Capsaicinoids from hot pepper (Capsicum annuum L.) and their phytotoxic effect on seedling growth of lettuce (Lactuca sativa L.)

Abstract

One new capsaicinoid, N-vanillyl-4E,6E-dien-8-methylnonanamide (4), along with nine known capsaicinoids, capsaicin (1), dihydrocapsaicin (2), N-vanillyloctanamide (3), nordihydrocapsaicin (5), N-vanillyldecanamide (6), homocapsaicin (7), N-vanillyl-4,8-dimethylnonanamide (8), homodihydrocapsaicin II (9), and homodihydrocapsaicin I (10) were isolated from the fruits of Capsicum annuum using semi-preparative high-performance liquid chromatography. The structural characterizations of the isolated compounds were elucidated by spectroscopic data and comparison with the literatures. Bioassays showed that the isolated capsaicinoids significantly reduced the radical length of Lactuca sativa seedling, this inhibition being dose-dependent.     

Copper-Catalyzed Defluorinative Hydroarylation of Alkenes with Polyfluoroarenes

A catalytic defluorinative hydroarylation of alkenes with polyfluoroarenes in the presence of dppbz-ligated Cu catalyst and silanes was developed. This method provides a straightforward and alternative avenue to synthetic important polyfluorinated arenes with readily available and bench-stable alkenes as latent nucleophiles, and therefore avoids conventional reliance on stoichiometric quantities of organometallic reagents. This reaction proceeds under very mild conditions and exhibits good functional group compatibility and high level of regioselectivity. The synthetic potential of this method was further demonstrated by a gram-scale synthesis, and an array of experimental studies were also carried out to elaborate the probable mechanism.     

Fast inspection of fruits using nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy is an indispensable technique for obtaining chemical structure information. Its quantitative and noninvasive properties have led to its growing popularity as an analytical tool in many fields, including biology, chemistry, medicine, and food science. During transportation and storage, chemical reactions among the many nutrients lead to a loss of food quality. In these circumstances, portable NMR spectrometers can readily be used for food inspection and quality control. Because of the heterogeneous tissue distribution in food, a high-resolution NMR method is required for detailed food inspection. Therefore, in this study, we demonstrated the feasibility of using an intermolecular double-quantum coherence signal to obtain high-resolution metabolic profiles of several fruits, including grape, cantaloupe, tomato, and watermelon. The resulting high-resolution NMR spectra facilitate the identification of important metabolites, which can be used as biomarkers for food quality control. The method established here may be adapted for food inspection using portable NMR equipment.     

超分辨荧光显微镜-显纳镜

2014年诺贝尔化学奖授予美国科学家Eric Betzig、德国科学家Stefan W.Hell和美国科学家William E.Moerner,表彰他们在"发展超分辨荧光显微镜"方面的贡献。超分辨荧光显微镜的出现,为深入研究生命过程的分子机制提供了新的工具和新的机遇。本文综述了三位获奖人发明的两种超分辨荧光显微镜的基本原理、方法发展和生物医学应用,并对国内相关研究进展作了简介。     

A Bipolar Transporter as an Efficient Green Fluorescent Emitter and Host for Red Phosphors in Multi‐ and Single‐Layer Organic Light‐Emitting Diodes

Multifunctional donor–acceptor compound 4,4′‐bis(dibenzothiophene‐S,S‐dioxide‐2‐yl)triphenylamine ( DSTPA ) was obtained by linking a strongly electron‐withdrawing core and a strongly electron‐donating core with a biphenyl bridge in linear spatial alignment. DSTPA not only has suitable HOMO and LUMO levels for easily accepting both holes and electrons, it was also demonstrated to have a high fluorescence quantum yield of 0.98 and a high triplet energy level of 2.39 eV. Versatile applications of DSTPA for bipolar transport, green fluorescent emission, and sensitizing a red phosphor were systematically investigated in a series of multi‐ and single‐layer organic light‐emitting devices. In traditional multilayer devices, it shows excellent performance both in an undoped fluorescent device (used as a green emitter and achieving maximum current and power efficiencies (CE and PE) of 12.6 cd A^?1 and 9.4 Lm W^?1, respectively) and in a red phosphorescent device (used as a host and achieving maximum CE and PE of 26.4 cd A^?1 and 26.3 Lm W^?1, respectively). Furthermore, DSTPA was also simultaneously used as an emitter, a hole transporter, and an electron transporter in a single‐layer device showing CE and PE of 5.1 cd A^?1 and 4.7 Lm W^?1, respectively. A single‐layer red phosphorescent device with efficiencies of 11.7 cd A^?1 and 12.6 Lm W^?1 was obtained by doping DSTPA with a red phosphor. The performances of all of the devices in this work are comparable to the best of their corresponding classes in the literature.     

Preparation and drug release property of CO2 stimulus-sensitive poly(N, N-dimethylaminoethyl methacrylate)-b-polystyrene nanoparticles

The CO₂ stimulus-sensitive nanoparticles based on poly(N, N-dimethylaminoethyl methacrylate)-b-poly styrene (PDMAEMA-b-PS) were prepared via surfactant-free miniemulsion reversible addition–fragmentation chain transfer (RAFT) polymerization. The as-prepared nanoparticles exhibited core–shell structure with about 120 nm in diameter. Their dispersion/aggregation in water can be adjusted by alternatively bubbling of CO₂ and N₂. Drug release from these nanoparticles can be accelerated (or delayed) by bubbling (or removing) of CO₂.     

The effect of aging during storage on the performance of a radial lip seal

Since aging is an inevitable phenomenon during storage of a radial lip seal, this study aims to investigate the effect of aging on the seal performance. An air oven aging test is conducted to produce aged rubber samples and seal products. An aging life prediction model is constructed to predict the equivalent material properties at any storage temperature. The material property parameters of aged rubber samples are measured in a uniaxial compression experiment. The pumping rate and friction torque of the seal are calculated through numerical simulation by using a mixed elastohydrodynamic lubrication (EHL) model. A bench test is used to verify the aging life prediction model and the simulation results of the EHL model. Finally, the verified EHL model is used to study how aging during storage affects the lip seal performance, as characterized by the leakage and friction torque.     

Temperature Effects on the Capacitance of an Imidazolium‐based Ionic Liquid on a Graphite Electrode: A Molecular Dynamics Simulation

Temperature‐dependent electric double layer (EDL) and differential capacitance–potential (C_d–U) curves of the ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIM⁺/PF₆^?) were studied on a graphite electrode by molecular dynamics simulations. It was found that all C_d–U curves were asymmetric camel‐shaped with higher C_d at negative polarization, attributed to the specific adsorption of BMIM⁺. In addition, the maxima of C_d at the negative polarization decrease monotonically with temperature due to the thicker EDL, whereas at the positive polarization they gradually increase from 450 to 550 K and decrease at 600 K. Such temperature effects at positive polarization may be understood in terms of the competition between two aspects: the weakening specific adsorption of BMIM⁺ allows more effective screening to the positive charge and overall increasing EDL thickness. Although the former dominates from 450 to 550 K, the latter becomes dominant at 600 K.