Photocatalytic reduction of methylene blue by formaldehyde in the presence of titanium dioxide and cadmium sulfide sensitized by (1-phenyl-5,6-benzoquinoline-2)-2,4-dihydroxystyryl iodide

New heterostructures of a dye, (1-phenyl-5,6-benzoquinoline-2)-2,4-dihydroxystyryl iodide, with TiO₂ and CdS were obtained and their photocatalytic activity in the reduction of methylene blue by formaldehyde was established under different irradiation conditions and with different dye concentrations. Explanations for the behavior found are proposed. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 1, pp. 40–45, January–February, 2008.     

Dependence of surface-enhanced Raman scattering from Calf thymus DNA on anions

Dependence of surface-enhanced Raman scattering (SERS) from Calf thymus DNA on anions is investigated.With the silver colloid,the bands at 732,960 and 1333 cm-1 for adenine (A),1466 cm-1 for deoxyribose,and 1652 cm-1 for the C=O group of thymine (T) are observably enhanced.With the presence of the Cl- or SO42- anions,the bands at 732 and 1326/1329 cm-1 for the symmetric stretching and skeletal vibrational modes of adenine (A) are dramatically enhanced,and the enhancement effect with the SO24- ion is more than that with the Cl- ion.The experimental results show that the DNA molecule can be adsorbed on the silver colloid particles through the C6N and N7 of adenine (A),the C=O of thymine (T) and deoxyribose.Moreover,the formed hydrogen bonding of the Cl- or S2O4- ions to the C6NH2 group of adenine (A) can induce larger C6N electronegativity,which is favor for the C6N/N7 cooperative adsorption on the (Ag) n colloid particles.     

Supramacromolecular self‐assembly: Chain extension,star and block polymers via pseudorotaxane formation from well‐defined end‐functionalized polymers

Dibenzo‐24‐crown‐8‐terminated polystyrene ( 5 ) was chain extended to “dimeric” 8 by pseudorotaxane formation with a ditopic guest, α,ω‐bis[p‐(N‐benzylammoniomethyl)phenoxy]heptane bis(hexafluorophosphate) ( 7 ). The three‐armed star polymer 11 was similarly formed by complexation of the dibenzo‐24‐crown‐8‐terminated polystyrene ( 5 ) with a tritopic secondary ammonium salt, 1,3,5‐tris[p‐(benzylammoniomethyl)phenyl]benzene tris(hexafluorophosphate) ( 10 ). Another three‐armed star polymer 13 was self‐assembled from dibenzo‐24‐crown‐8‐terminated polystyrene ( 5 ) and a tetratopic paraquat compound, 1,2,4,5‐tetrakis{p‐N‐[(N′‐methyl‐4,4′‐bipyridinium)methylphenyl]}benzene octakis(hexafluorophosphate) ( 12 ). The above chain extension and star polymer formation processes seemed to be cooperative; that is, the second and third complexation steps proceed with stepwise higher efficiencies than statistically expected. Dibenzo‐24‐crown‐8‐terminated polystyrene ( 5 ) was chain extended with secondary ammonium terminated polystyrene 14 , forming 16 , and also self‐assembled with a secondary ammonium ion terminated polyisoprene 15 to form supramolecular block copolymer 17 . These processes were examined by NMR, mass spectrometry and viscometery. Thus, although binding in these systems is not particularly strong (association constants <10⁴ M^?1), these examples provide proof‐of‐principle that pseudorotaxane formation is a viable concept for chain extension and self‐assembly of novel types of block copolymers and star polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3518–3543, 2009     

A model for structural relaxation in amorphous glassy polymers based on the aggregation–fragmentation theory

Governing equations are derived for the kinetics of physical aging in polymeric glasses. An amorphous polymer is treated as an ensemble of cooperatively rearranged regions (CRRs). Any CRR is thought of as a string of elementary clusters (ECs). Fragmentation of the string occurs at random times at any border between ECs. Two strings aggregate at random instants to produce a new string. Aggregation and fragmentation are treated as thermally activated processes, and the rate of fragmentation is assumed to grow with temperature more rapidly than the rate of coalescence. A nonlinear differential equation is developed for the distribution of CRRs with various numbers of ECs. Adjustable parameters of the model are found by the fitting of experimental data for polycarbonate, poly(methyl methacrylate), polystyrene, and poly(vinyl acetate) (PVA). Fair agreement is established between observations and results of numerical simulation. For PVAc, the relaxation spectrum found by matching data in a calorimetric test is successfully employed to predict experimental data in a shear relaxation test. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1312–1325, 2001     

Inferior players in simple games

Power indices like those of Shapley and Shubik (1954) or Banzhaf (1965) measure the distribution of power in simple games. This paper points at a deficiency shared by all established indices: players who are inferior in the sense of having to accept (almost) no share of the spoils in return for being part of a winning coalition are assigned substantial amounts of power. A strengthened version of the dummy axiom based on a formalized notion of inferior players is a possible remedy. The axiom is illustrated first in a deterministic and then a probabilistic setting. With three axioms from the Banzhaf index, it uniquely characterizes the Strict Power Index (SPI). The SPI is shown to be a special instance of a more general family of power indices based on the inferior player axiom. Received: December 1999/Final version: June 2001     

基于合作博弈的买方抗衡势力市场绩效与卖方工艺创新强度分析

设计了由一个上游企业和两个下游企业所构成的产业链纵向关系模型,建立了纵向一体化、纵向分离且下游企业均无买方抗衡势力、以及单个下游企业具有买方抗衡势力三种情况下上游企业的工艺创新强度计算模型,分析了下游企业存在买方抗衡势力时市场中均衡的批发价格、零售价格、企业利润以及社会福利的变化,给出了相应的结论,同时也说明了“加尔布雷斯假说”在本文的结构下没有得到验证。     

Shapley值与Winter值的解析关系

鉴于 Shapley 值和 Winter 值都是局中人边际贡献的平均值,探究了它们之 间的解析关系.证明了 Shapley 值是 Winter 值在层次结构集上对称概率分布下的期望均值. 作为这一结论的一个推论, 证明了 Shapley 值是 Winter 值在层次结构集的任意相似类中的平均值. 最后,还指出了这一结 论与推论的等价性.研究结果不仅扩展了 Shapley 值和 Owen 值与此对应的解析关系, 还大大简化了这些关系的已有证明.     

Yb3+:Er3+共掺氟磷酸盐玻璃的发光和激光性能

稀土掺杂氟磷酸盐玻璃是可以满足波分复用系统及超短脉冲系统对带宽和平坦增益要求的激光材料之一。研究了其中一种增益带宽宽,发光谱线平坦的镱铒共掺氟磷酸盐玻璃,其计算半峰全宽为51nm。对反映宽带性能的有效增益截面的研究表明,该镱铒共掺氟磷酸盐玻璃在1530～1580nm之间有一平坦的有效增益截面谱线,证明其宽带特性明显优于掺铒磷酸盐玻璃。对Yb^3 离子敏化效率的研究显示,在镱铒比为10：1时,Er^3 离子的吸收截面和发射截面达最大值,分别为0．6601pm^2和0．7325pm^2,表明此比值下Yb^3 对Er^3 的能量传递效率最高。实验结果显示Yb：Er氟磷酸盐玻璃可用作带宽宽,增益平坦,可实现高能输出的激光器和光纤放大器的基质玻璃材料。     

双航海惯导联合旋转调制协同定位与误差参数估计

单轴/双轴旋转调制航海惯导备份配置满足了舰艇对于定位精度、可靠性、成本的综合要求,但系统间缺少信息融合。针对此问题,以单轴旋转惯导的姿态误差、速度误差、位置误差与双轴旋转惯导对应误差的差值以及两套惯导的陀螺常值漂移、水平加速度计常值零偏为系统状态,并以二者间扣除杆臂效应后的速度及位置的差值为观测量,通过联合旋转调制,改变两套系统IMU的相对姿态关系。分段常值可观测性分析表明,所有系统状态完全可观。建立了定位误差预测方程,对单轴旋转惯导方位陀螺漂移造成的定位误差进行预测补偿。实验结果表明,对单轴旋转惯导方位陀螺漂移造成的定位误差预测补偿后,其定位误差减小了30%,不仅满足了高可靠性的要求,而且提高了故障情况下的导航精度。