Temperature‐dependent location of a weakly segregated block copolymer in binary blends of block copolymers

The phase behaviors of binary blends of poly(styrene‐b‐butadiene) block copolymers were investigated by a small‐angle X‐ray scattering technique. The blends were composed of weakly segregated one in a random micellar phase and the other in a cylindrical phase with similar molecular weights and complementary volume fractions. Morphologies, domain spacings, and order–disorder transition temperatures of the blends indicated that the junctions of the constituent block copolymers share the interface at low temperatures. The domain spacing decreased as temperature increased in a blend with a small amount of the weakly segregated block copolymer. In the cases of the blends with a large amount of the weakly segregated constituent, domain spacing increased with increasing temperature. These results implied that some of the weakly segregated block copolymer moved from the interface to one microdomain at higher temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 470–476     

Hydrolytic degradation of polyisobutylene and poly‐L‐lactide–based multiblock copolymers

The hydrolytic degradation of a series of poly‐L ‐lactide (PLLA)‐polyisobutylene (PIB) multiblock copolymers was studied in phosphate buffer solution (pH = 7.4) at 37 °C. The multiblock copolymers were synthesized by chain extension of PLLA‐b‐PIB‐b‐PLLA triblock copolymers, which were obtained by ring‐opening polymerization of L ‐lactide initiated by hydroxyallyl telechelic PIB. The degradation strongly depended on the PLLA segment length. At constant PIB segment length, the multiblock copolymer with the shortest PLLA segment length (DPn = 10), showed significant weight loss after 8 weeks, whereas weight loss for DPn = 36 was only observed after 24 weeks. The gel‐permeation chromatographic analysis showed a similar decrease in the number‐average molecular weight (M_n) with time further supporting the weight loss data. Dynamic mechanical analysis showed a decrease in ultimate stress and modulus with time. The crystallinity of multiblock copolymers changed significantly with degradation time as indicated from differential scanning calorimetric analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3767–3774, 2010     

Hydrolytic Kinetic Resolution of Terminal Epoxides catalyzed by Novel Bimetallic Chiral Co (Salen) Complexes

Novel bimetallic chiral Co (salen) complexes bearing transition‐metal salts have been synthesized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity in hydrolytic kinetic resolution (HKR) of racemic terminal epoxides and consequently provided enantiomerically enriched epoxides (up to 99% ee).     

Synthesis,thermal property and antifungal evaluation of pyrazine esters

Synthesis, thermal properties, as well as antifungal assessment of pyrazine esters were handed in this work. The metal-free esterification of pyrazinyl methanol and acid chloride derivatives in a stoichiometric ratio yielded the following compounds: pyrazin-2-ylmethyl benzoate (3a), (5-methylpyrazin-2-yl) methyl benzoate (3b), 1-(pyrazin-2-yl) ethyl benzoate (3c), 2-(pyrazin-2-yl) ethyl benzoate (3d), pyrazin-2-ylmethyl pivalate (3e). The spectral results totally showed that the synthesis conditions used permitted the compounds to be produced with great yield. The characterization included ¹H NMR, ¹³C NMR, IR, HRMS and organoleptic tests. Their thermal degradation process was examined by using the TG (thermogravimetry) and DSC (differential scanning calorimeter) methods. The pyrolysis products of the pyrazine esters in inert and oxidative atmospheres were analyzed by the Py-GC/MS (pyrolysis–gas chromatography/mass spectrometry) method. It revealed that 3a–3e were totally evaporated throughout the pyrolysis experiments at low temperatures. And they evaporated with high relative contents in pure nitrogen (86.12%–94.17%) and oxidative (75.01%–88.85%) atmospheres, with only a small amount decomposing into a series of substances. Additionally, the in vitro antifungal effects of compounds 3a–3e against R. solani, P. nicotianae, F. oxysporum, F. graminearum, and F. moniliforme were further investigated using the mycelial growth rate methodology. The findings shown that compound 3c has 94% and 80% inhibitor rates at 0.5 mg/ml against R. solani and P. nicotianae, respectively, with an EC₅₀ value (half maximum effective concentration) of 0.0191 mg/ml and 0.1870 mg/ml, respectively. Similarly, that of compounds 3a and 3b exhibited 82% and 91% at 0.5 mg/ml against R. solani, with an EC₅₀ value of 0.0209 mg/ml and 0.0218 mg/ml, respectively. The molecular docking of compound 3c with SDH (Succinate dehydrogenase) was preliminarily performed to reveal the binding modes in active pocket and analyze the interactions between the molecules and the protein.     

超声自冲铆复合连接成形性及力学行为研究

该文选用6061和2A12航空铝合金薄板材料,进行自冲铆接和超声自冲铆复合连接试验,基于拉伸-剪切和电子显微镜测试,研究超声自冲铆接成形性及力学行为。结果表明：超声自冲铆接头较自冲铆接头的内锁量提升了44.8%;其钉头高度下降了34.4%;超声自冲铆接头的静载强度提升了18.1%,缓冲吸震性能提升了17.5%;超声焊接致使自冲铆接头的铆钉颈部与上板接触区域、铆钉腿部与上板接触区域形成固相焊;超声焊接可有效提高自冲铆接头的稳定性。     

倾斜薄煤层开采工作面覆岩活动的规律

为解决倾斜薄煤层顶板控制技术难题,以东风煤矿倾斜薄煤层开采为背景,运用RFPA2D软件,建立数值模型,分析不同倾角下薄煤层工作面覆岩活动规律及顶板失稳特征。结果表明:倾斜薄煤层开采后,直接顶从采空区中部偏上向采空区弯曲,最后发生断裂破坏形成冒落带,顶板冒落沿层面向下滑动,冒落呈不对称形状;倾斜薄煤层工作面煤体上段顶板压力最大,下段次之,中段最小;随着煤层倾角的增大,顶板沿煤层倾斜方向的分力增大,垂直作用在支架上的分力减小,导致工作面推进方向的工作面矿压显现逐渐变缓,顶板下沉量也将变小。该研究为类似地质条件的倾斜薄煤层工作面顶板控制提供了理论依据。     

Novel inorganic morphologies formed in polyimide/silica hybrid films

2-(4-Aminophenyl)-5-aminobenzimidazole was used to prepare polyimide/silica hybrid films via sol-gel process. At 40 wt.% silica content, hybrid films were still translucent. No noticeable silica particle has been observed. Unexpectedly, after treating at 800 °C, novel morphologies of silica were observed on the surface of inorganic films, which changed from homogeneous to sea-island and to co-continuous structure with increasing silica content in the matrix. Hydrogen bonding between NH in imidazole and silanol group results that silica tends to linear structures, which is considered as the main reason for this morphological change.     

Pheromone synthesis. Part 244: Synthesis of the racemate and enantiomers of (11Z,19Z)-CH503 (3-acetoxy-11,19-octacosadien-1-ol), a new sex pheromone of male Drosophila melanogaster to show its (S)-isomer and racemate as bioactive

The enantiomers of (11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol were synthesized from the enantiomers of 3,4-epoxy-1-butanol PMB ether. Its racemate was also synthesized. Its (S)-isomer and racemate were shown to possess the same pheromone activity as CH503, a long-lived inhibitor of male courtship in Drosophila melanogaster, although the racemate was less active.     

Effects of Ar/H/N‐ion bombardment on the surface free energy and friction behavior of the fullerene‐like hydrogenated carbon (FL‐C:H) film

The surface modification of the fullerene‐like hydrogenated carbon (FL‐C:H) film was achieved by bombardment using Ar, H, and N ions, respectively. A systematic comparison of X‐ray photoelectron spectroscopy (XPS) and Fourier transformation infrared(FTIR) spectra was made between the FL‐C:H film and ion‐bombarded films. The results show that ion bombardment resulted in the increase of sp³ C content, specially, new C? N bonds were formed for N‐ion‐bombarded film. The contact angle (CA) and friction coefficient of those films were measured. The surface free energy evaluated from the contact angle increased for ion‐bombarded films, and the most obvious increase was obtained for N‐ion‐bombarded film. The friction coefficient decreased for H‐ion‐bombarded film whereas it increased for N‐ion‐bombarded film, and the friction coefficient of Ar‐ion‐bombarded film was close to that of the FL‐C:H film. Copyright © 2008 John Wiley & Sons, Ltd.     

水解酸化工艺在医院污水处理中的应用

简述了医院污水处理的现状,对某小型综合医院污水处理系统所采用的＂水解酸化＋混凝沉淀＋接触消毒＂工艺流程及运行结果进行了分析,得出了该工艺符合《医疗机构水污物排放标准》的要求,适合推广应用的结论。