Exploring Microstructures and Interphase Properties of Surface- Grafted Diblock Copolymers in a Homopolymer Melt by Self-Consistent Field Theory Simulations

Polymeric self-consistent field theory is used to investigate microstructures and interphase properties of diblock copolymers grafted onto solid surfaces in a homopolymer melt. The calculations show that the grafted diblock copolymers can self-assemble into hemispherical microstructures at low grafting densities of the diblock copolymers. The morphology transforms into hemicylinder-like and sandwich-like lamellar microstructures with an increase in the chain-grafting density. The effective thickness of the grafted block layer and the interphase width between the homopolymer melt and the grafted copolymers strongly depend on the physicochemical parameters of the system, such as the composition of the grafted copolymer, the chemical incompatibility between the different components, the length ratio of grafted copolymer to homopolymer, and the grafting density of the diblock copolymers. In addition, the above computational results of microphase-separated structures and interphase properties are qualitatively compared with our previous experimental observations. The comparison indicates that our theoretical results not only reproduce the general feature of the experimental observations, but also elucidate the internal structural information and complement the findings in the region of high grafting densities of diblock copolymers.     

顺序注射氢化物发生-原子荧光光谱法同时测定环境水样中砷和镉

目的考察了光电倍增管负高压、砷和镉灯电流、原子化器高度、载气流量、屏蔽气流量、增敏剂等因素对测定结果的影响。方法建立一种顺序注射氢化物发生-原子荧光光谱法同时测定水样中砷和镉含量的方法。结果载流HCl的浓度为0.60 mol/L,KBH4质量浓度为20g/L,增敏剂硫脲和钴离子的质量浓度分别为80 g/L和70 g/L时,同时测定砷和镉的效果最佳。在最佳实验条件下,砷和镉的检出限分别为0.009 3μg/L和0.12μg/L,加标回收率为92.3%～103.9%,相对标准偏差小于3.5%,被测水样中共存离子对砷和镉的测定没有干扰。结论该法操作方便、快速,用于环境水样中砷和镉的同时测定,具有很好的可行性和实用性。     

开口型管道内瓦斯爆炸冲击波动压的数值模拟

为了研究瓦斯爆炸冲击波的动压演化规律,利用数值模拟软件模拟开口型管道内的爆炸。结果表明:动压与流速在时间上存在较好的对应关系,基本同时出现正向和反向的峰值;动压在3个方向上不仅伴随传播距离的增大而不断增大,也伴随传播时间的延长而增大;沿管道方向(火焰传播方向)上的最大动压值是其他2个方向(管道径向)上的数千倍;相比爆炸超压而言,管道径向上的动压对爆炸破坏效应的影响较小,而沿管道方向上的动压造成的破坏效应不能忽视;验证了动压与流速的平方呈正比关系,同时通过分析给出了动压基于管道几何尺寸和流速的经验公式。     

岩层与地表移动的广义下沉公式

在考虑岩性差异的条件下,推导出了岩层与地表移动的广义下沉公式,最后列举了其应用意义和实例。     

Microcomputer mass-spectral information system with categorized data bases

Twelve special-purpose mass spectral data bases (MIMS-i) containing data on alkaloids, organometallic compounds, steroids, amino acids, etc., were established on an IBM-PC/XT microcomputer. A retrieval system incorporating different query and search methods was built for these data bases. The structures and methods used in the establishment of the data bases, some special search procedures and the capability of the system are discussed.     

Improving aging resistance of PIM-1 thin films by nano-TiO2 filler used for robust solvent permeation

Polymers of intrinsic microporosity (PIMs) are promising materials for membrane separation because their special rigid and contorted structures contribute to high permeability. However, their chain rearrangement to fill excessive free volume makes the permeability stability a tough challenge. In this work, we report on a new use of rutile nano-TiO₂ to mitigate the physical aging of PIM-1 (a typical PIM) nanofilms for stable permeability by mixing matrix. It was shown that the PIM-1 membrane incorporated with nano-TiO₂ displayed remarkably higher aging resistance with a lower swelling degree in long-term ethanol soaking, having more stable ethanol permeance with only a 5% decrease after 35 days, lower than 25% of the pure one. The mechanism of anti-aging was revealed by molecular simulation, thermal, tensile mechanical, and dynamic mechanical analysis. It was found that nano-TiO₂ had good compatibility with PIM-1 due to strong coordination interaction, making its uniform dispersion in polymer. Additional solvent permeation channels were also created to increase solvent permeance without compromising solute rejection. Due to the reliable interaction of nano-TiO₂, which makes particles serve as physical crosslinking points, the movement of PIM-1 chains was limited partially to mitigate aging, enabling PIM-1-based membranes to have robust solvent permeation.     

计算机辅助针灸诊疗专家系统-ZES及其壳体-KZES

本文论述ZES的功能和开发技术。描述了系统中推理的数学模型及其理论基础,最后阐述了ZES的外壳可用作建造中医专家系统的工具。     

具有光引发活性腰果酚衍生物的合成及其UV固化

以腰果酚与4-溴甲基二苯甲酮为原料,合成了具有光引发活性的腰果酚衍生物,收率86%。 该衍生物的光引发活性优于普通的二苯甲酮。 在不加其它光引发剂的情况下,UV光照30 s该液体衍生物即可固化。 该衍生物与腰果酚不同比例的混合物,也可进行UV 固化,腰果酚含量越高,所需固化时间越长。膜的硬度为3H-5H,且具有较好的耐溶剂与耐酸碱性能,可望用于防腐漆中。     

Controlling chemoselective transformations of 4-acylpyridines via a Pd–C catalytic hydrodechlorination–hydrogenation

A novel Pd–C catalytic hydrodechlorination–hydrogenation was developed for a multi-step one-pot transformation of 4-acylpyridines. Under the selected conditions, 4-benzoylpyridines and 4-alkanoylpyridines were chemoselectively converted into the corresponding 4-benzylpiperidine hydrochlorides and α-alkyl-4-piperidinemethanol hydrochlorides, respectively. This catalytic method was performed simply by an addition of 1 equiv of ClCH₂CHCl₂ to the conventional hydrogenation system and directly gave the crystalline piperidine hydrochlorides in practical quantitative yields.     

Characterization of chitosan microparticles reinforced cellulose biocomposite sponges regenerated from ionic liquid

The chitosan-microparticles reinforced cellulose biocomposite sponges regenerated from ionic liquid were prepared and characterized. Fourier transform infrared (FTIR) spectroscopy confirmed that the cellulose dissolved in 1-allyl-3-methylimidazolium chloride without derivatization. Chitosan particles as reinforcement were incorporated into the cellulose matrix. FTIR spectra indicated hydrogen bonding between hydroxyl groups of cellulose and chitosan. The biocomposite sponges showed uniform three-dimensional interconnected porous structures. The breaking strength of the sponges increased significantly, from 0.09 to 0.32 MPa with the addition of 1.0 wt% chitosan. The sponges also demonstrated excellent antibacterial activity against S. aureus and E. coli with the average inhibition zone diameters >2 mm and the inhibition rate higher than 80 %. Furthermore, the biocomposite sponges exhibited good moisture penetrability and high porosity. The water uptake ability of the sponge was >25 times of its weight in water with a fast swelling. The chitosan/cellulose composite sponge is expected to be a promising material for potential applications as wound dressing.