Highly Symmetric Patchy Multicompartment Nanoparticles from the Self-Assembly of ABC Linear Terpolymers in C-Selective Solvents

Multicompartment micelles, especially those with highly symmetric surfaces such as patchy-like, patchy, and Janus micelles, have tremendous potential as building blocks of hierarchical multifunctional nanomaterials. One of the most versatile and powerful methods to obtain patchy multicompartment micelles is by the solution-state self-assembly of linear triblock copolymers. In this article, we applied the simulated annealing method to study the self-assembly of ABC linear terpolymers in C-selective solvents. Simulations predict a variety of patchy and patchy-like multicompartment micelles with high symmetry and also yield a detailed phase diagram to reveal how to control the patchy multicompartment micelle morphologies precisely. The phase diagram demonstrates that the internal segregated micellar structure depends on the ratio between the volume fractions of the two solvophobic blocks and their incompatibility, whereas the overall micellar shape depends on the copolymer concentration. The relationship between the interfacial energy, stretching energy of chains and the micellar morphology, micellar morphological transition are elucidated by computing the average contact number among the species, the mean square end-to-end distances of the whole terpolymers, the AB blocks in the terpolymers, the AB diblock copolymers, and angle distribution of terpolymers. The anchoring effect of the solvophilic C block on micellar structures is also examined by comparing the morphologies formed from ABC terpolymers and AB diblock copolymers.     

Study on the wettability of polyethylene film fabricated at lower temperature

Polyethylene films were prepared with phase separation at lower temperatures. The wettability of such films varied from hydrophobicity to superhydrophobicity as the processing temperature decreased owing to the increase of surface roughness. Storing the as-prepared films at subzero temperature (-15 °C), it was found that the water contact angle of the film decreased obviously, and the decrease depended on the corresponding roughness. Further keeping the as-prepared films at room temperature for 30 min, the water contact angle would return to the normal value, which indicated that the reversible switching of surface wettability can be controlled by the environmental temperature.     

剪切聚合物分散液晶散射偏光特性

介绍了拉伸聚合物分散液晶和散射偏光片概念,实验制备了剪切聚合物分散液晶样品,给出了对聚合物分散液晶样品施加剪切应力的偏光特性光谱分析.实验结果表明,吸收偏光片前置和后置样品的散射偏光效果相同,样品在绿光550nm波长处最大透光率T//～60%,最小透光率T┴～10%,偏振度P～70%.实验结果对于其他散射偏光片具有普遍...     

Product distributions of Fischer-Tropsch synthesis over Co/AC catalyst

The product distributions of Fischer-Tropsch synthesis over Co/AC catalyst are investigated under different reaction conditions in an integral fixed bed reactor.It is found that the product distributions deviate from the ASF distribution.The deviation from ASF distribution is analyzed by taking the readsorption of alkenes and the following secondary reaction into consideration.It is noted that the contents of alcohol,alkene and alkane decline with the increasing carbon number,showing a slighter declining tendency of alkanes than those of alkenes and alcohols.It is also found that high temperature,space velocity,H2/CO in feed gas and low pressure are preferential for light hydrocarbons and alcohols while against the chain propagation.The effect of space velocity on the product distributions especially on the light products is not obvious.It is noticed that low temperature,space velocity,H2/CO and high pressure lead to high contents of alcohols;high temperature,H2/CO and low space velocity lead to high contents of alkanes.The effect of pressure on the amounts of alkanes is not significant;high space velocity and low temperature,pressure,H2/CO are preferential for alkenes.     

通解矩阵(英文)

用消元法程序在计算机上求含ｍ个方程ｎ个未知量的线性代数方程组的通解的问题现在仍然没有得到解决．本文首先给出一个称为“通解矩阵”的新定义，然后证明两个有关定理．以此为基础，使解决上述问题成为一件容易的事．     

硅微条探测器的辐射损伤试验

测量了硅微条探测器在辐照前后的坪曲线、脉冲高度与偏置电压的关系，及辐照后的总漏电流和黑洞的大小.     

Studies on the phase structure of ethylene‐vinyl acetate copolymers by solid‐state 1H and 13C NMR

The phase structure of a series of ethylene‐vinyl acetate copolymers has been investigated by solid‐state wide‐line ¹H NMR and solid‐state high‐resolution ¹³C NMR spectroscopy. Not only the degree of crystallinity but the relative contents of the monoclinic and orthorhombic crystals within the crystalline region varied with the vinyl acetate (VA) content. Biexponential ¹³C NMR spin–lattice relaxation behavior was observed for the crystalline region of all samples. The component with longer ¹³C NMR spin–lattice relaxation time (T₁) was attributed to the internal part of the crystalline region, whereas the component with shorter ¹³C NMR T₁ to the mobile crystalline component was located between the noncrystalline region and the internal part of the crystalline region. The content of the mobile crystalline component relative to the internal part of the crystalline region increased with the VA content, showing that the ¹³C NMR spin–lattice relaxation behavior is closely related to the crystalline structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2199–2207, 2002     

Resonant interactions of Tollmien-Schlichting waves in the boundary layer on a flat plate

Resonant interaction phenomena of Tollmien-Schlichting waves (T.-S. waves) are examined experimentally by spectral analysis method. Results demonstrate that, in the spectra measured in the vicinity of the critical layer of the unstable boundary layer, the energy of T.-S. waves concentrates in a narrow band of frequency with one to three peaks in the power spectra corresponding to the eigenfrequencies of T.-S. waves and the frequency with maximum growth rate located between the upper and lower branches of the neutral curve. The resonant interactions transfer the energy of these eigencomponents to their subsequent subharmonics in a range ofR _δ* where their growth rates increase from zero to a maximum value, and the boundary layer becomes turbulent after the third resonant interaction.     

表面Mo修饰提高CeTiO_x催化剂低温脱硝性能（英文）

近年来,以雾霾为代表的大气污染问题严重影响到经济社会的可持续发展.其中,氮氧化物(NOx)的大量排放是导致雾霾天气的重要原因之一.氨选择性催化还原(NH3-SCR)是目前消除氮氧化物的主流技术,低温NH3-SCR更是广泛应用于钢铁、焦化、水泥、玻璃、陶瓷和垃圾焚烧等行业的烟气排放治理.传统的V2O5-WO3/Ti O2催化剂活性温度高(300–400 oC)且钒具有生物毒性,因此亟待开发环境友好的低温非钒基脱硝催化剂.最近, Ce Ti Ox基催化剂由于在中高温段(250–400 oC)表现出优异的脱硝性能而得到广泛关注.然而,该催化剂仍面临低温活性差及抗硫性能差的问题,制约了其工业化应用.研究显示,添加过渡金属可提高Ce Ti Ox基催化剂的脱硝活性和抗硫中毒性能,这主要是因为过渡金属的添加可以有效改善催化剂的氧化还原性能和表面酸性.Mo O3作为一种可以提供大量酸性位的氧化物,常被用作助剂改善钒钨钛催化剂的活性.研究显示, Mo O3的引入可以促进催化剂中钒物种的分散度以及提高表面酸性.基于此,我们制备了一系列不同Mo含量的Mo O3/Ce Ti Ox催化剂,以期提高Ce Ti Ox催化剂的低温脱硝性能及抗SO2中毒能力,并着重研究表面Mo的修饰对Ce Ti Ox催化剂物理化学性质的影响.研究发现,表面Mo修饰可以显著提高Ce Ti Ox的低温催化活性,其脱硝效率在150 oC即可达到80%,同时抗SO2中毒能力也得到增强.进一步借助X射线衍射、比表面积测定、氢气程序升温还原、氨气程序升温脱附和X射线光电子能谱等方法对催化剂进行了全面表征分析.结果显示,表面Mo修饰对Ce Ti Ox催化剂物理化学性质的影响与其脱硝性能有着密不可分的关系.首先,钼物种主要是以Mo O3的形式存在于Ce Ti Ox表面,其最佳的负载量为4wt.%.其次,表面Mo的沉积显著提高了催化剂的表面酸量,尤其是Br?nsted酸位的数量,而表面酸位的增加有利于催化剂吸附与活化反应物种NH3;同时,表面Mo修饰还减弱了硝酸盐在催化剂表面的吸附,进一步促使NH3-SCR反应按照Eley-Rideal机理顺利进行.最后,该催化剂在H2O和SO2存在的条件下仍具有最佳的脱硝性能,因而有望用于实际含SO2的低温烟气脱硝.