关于绕任意机翼非定常流动的一种无条件稳定的欧拉方程解

本文给出了绕二维与三维刚性或弹性振动机翼非定常无粘流动的欧拉方程解。首先利用Jameson的有限体积方法建立了求解欧拉方程的Runge-Kutta方法。为了提高受Runge-Kutta法稳定性限制的时间步长,文中采用了变系数的残值光顺方法。该方法避免了常系数残值光顺引起局部流场损失较大的问题。同时可在保证原计算格式精度要求下,大幅度提高计算时间步长,从而提高了计算效率。文中以二维与三维矩形机翼为例,分别对其在跨音速流场中作则性或弹性振动的非定常气动力进行了计算,研究了不同振动频率对流动产生的影响。部分计算结果与相应实验结果进行了比较。结果证明本方法是可靠的,可以用于求解绕任意运动机翼非定常流动问题。     

盐生杜氏藻RNAi应用中的电激转化条件

采用了两种电激模式-高电场强度低电容模式下3～7kV／cm和低电场强度高电容模式下300-500V／cm转化质粒pBl221-cat；PCR扩增检测cat基因部分序列及组织化学染色法GUS检测也同时证明质粒pBl221-cat在盐生杜氏藻中瞬时表达。在此基础之上，插入pds基因的正反向重复序列，构建RNAi表达载体pBIRNAI-Dsa，电激方法转入杜氏盐藻细胞，荧光定量PCR结果表明，转入干涉载体pBIRNAI-Dsa的实验组的pds基因表达显著下降，最低达对照组的28％，表明表达受到抑制。     

Synthesis of Cellulose Long-Chain Esters in 1-Butyl-3-methylimidazolium Acetate: Structure-Property Relations

In this study, we prepared cellulose long-chain esters homogeneously in 1-butyl-3-methylimidazolium acetate, using cotton linter as the raw material, long-chain fatty acid as the esterification agent and paratoluensulfonyl chloride as the co-reactant. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were used to characterize the product. The maximum degree of substitution was found to be 1.53 when the molar ratio of cellulose, lauric acid and paratoluensulfonyl chloride was 1 : 6 : 6, provided that the reaction temperature was 60°C and the reaction time was 24 h. The mechanical property of the free-film made of cellulose laurate was also tested. It was found that the toughness of cellulose laurate was much better than that of cellulose acetate.     

Fabrication of Patterned Conducting Polymers on Insulating Polymeric Substrates by Electric‐Field‐Assisted Assembly and Pattern Transfer

Summary: The use of electrostatically addressable templates for the directed assembly of conducting polymers and pattern transfer to another polymer substrate is demonstrated. Doped conducting polyaniline was selectively assembled on the patterned template assisted by a DC electric field. Adding an insulated silicon dioxide layer onto the surface of the silicon wafer is critical to the formation of patterned PANi rather than a PANi film. After deposition, it was demonstrated that by compression molding or solution casting methods, patterned PANi can be completely transferred to a secondary polymer substrate, such as an NBR sheet or a polyurethane film. The conductivity of PANi lines on the PU film was found to be as high as 0.87 S · cm⁻¹. The simple one‐step assembly process for patterning conductive polymers and transfer provides a promising nanomanufacturing approach for cost‐effective and high performance flexible nanoelectronics and biosensors.

Optical image of PANi‐assembled templates with patterned gold lines connected to negative electrodes at 10 V for 1 min.     

Synthesis and Photoconductivity Study of C60‐Containing Styrene/Acrylamide Copolymers

The C₆₀‐containing copolymers were prepared by reaction of styrene (St)/acrylamide (Am) copolymers with C₆₀ in toluene. By means of UV‐Vis spectroscopy, the C₆₀ content in the copolymers was determined to be up to 1.45 wt.‐%. The results show that with increasing the amide molar fraction in the copolymers, the C₆₀ content increases and the molar ratio C₆₀/amide group decreases. It was also revealed that the reactivity of the amide group with respect to C₆₀ could be enhanced by increasing the reaction temperature. C₆₀‐containing St/Am copolymers were characterized by DSC, GPC, XRD and UV‐Vis spectroscopy. Experimental results indicate that these C₆₀‐containing polymers reveal good photoconductivity, with the t_1/2 value of the better one (B8) being about 1.88 s, and photoconductivity could be enhanced on increasing the C₆₀ content in the copolymers.     

基于多质点模型的准球形丝阵参数优化研究

基于多质点薄壳模型对准球形丝阵负载参数进行优化,使得终态等离子体具有预期的内爆特性。通过对丝阵初始位形优化,可以获得期望的终态等离子体壳纵横比,并且终态纵横比对负载初始质量变化不敏感。对于固定电流波形（峰值1.2 MA、上升时间80 ns）,优化计算了初始丝长度15.4 mm的丝阵线质量。结果表明,当丝阵初始线质量约为150 g/cm时,赤道半径为2 mm、纵横比为1的终态等离子体壳具有最大动能1.5 kJ。同时,还针对不同幅度及上升时间的电流进行优化计算,计算结果表明终态等离子体壳的优化的最高动能与电流峰值平方成正比,与最高动能相应的线质量与电流上升时间平方成正比。     

随机填充增殖剂球床内载气流动特性数值模拟

固态氚增殖包层是聚变堆及聚变-裂变混合堆产氚包层的重要候选结构之一,其球床通道内载气流动特性将影响氚提取效率。利用离散元方法（DEM）生成随机填充增殖剂球床,通过径向孔隙率分布验证其合理性,计算流体力学（CFD）模拟计算其通道内气体流场特征。模拟得到：球床内吹扫氦气流速随孔隙率波动并随入口流速增大而均匀增大,通道内氦气流向及流速变化显著,Blake-Kozeny方程可良好预测该随机填充球床通道压降。     

用相律分析固体物质分解反应的同时平衡

本文应用相律分析不同固体物质分解反应中的同时平衡实例 ,得出这类系统中最多允许同时平衡的反应数目与分解产生气体种类数的定量关系 ,并指出维持同时平衡的条件     

Bifunctional thiophosphinamide catalyzed highly enantioselective Michael addition of acetone to (E)-2-azido β-nitrostyrenes and the subsequent reductive cyclization

We have proven that primary amine/thiophosphinamide incorporating (1R,2R)-1,2-diphenylethane-1,2-diamine is an efficient catalyst for the asymmetric Michael addition of acetone to (E)-2-azido β-nitrostyrenes. Under the optimal reaction conditions, the corresponding Michael addition products were obtained in excellent yields with almost perfect stereocontrol. Upon treatment with Et₃SiH/InCl₃, the Michael addition products could be successfully converted to the related 2-methyltetrahydroquinolines in acceptable yields with moderate to excellent diastereoselectivity and without appreciable loss in optical purity. This process provides a highly enantioselective pathway for the synthesis of biologically important 2-methyltetrahydroquinoline derivatives.     

Photoredox Nickel-Catalysed Stille Cross-Coupling Reactions

The Stille cross-coupling reaction is one of the most common strategies for the construction of C−C bonds. Despite notable strides in the advancement of the Stille reaction, persistent challenges persist in hindering its greener evolution. These challenges encompass multiple facets, such as the high cost of precious metals and ligands, the demand for various additives, and the slow reaction rate. In comparison to the dominant palladium-catalysed Stille reactions, cost-effective nickel-catalysed systems lag behind, and enantioconvergent Stille reactions of racemic stannanes remain undeveloped. Herein, we present a pioneering instance of nickel-catalysed enantioconvergent Stille cross-coupling reactions of racemic stannane reagents, resulting in the formation of C−C bonds in good to high yields with excellent stereoselectivity. This strategy provides a practical, scalable, and operationally straightforward method for the synthesis of C(sp³)−C(sp³), C(sp³)−C(sp²), and C(sp³)−C(sp) bonds under exceptionally mild conditions (without additives and bases, ambient temperature). The innovative use of synergistic photoredox/nickel catalysis enables a novel single-electron transmetalation process of stannane reagents, providing a new research paradigm of Stille reactions.