乙酸氧钛对碳酸二甲酯与苯酚酯交换的催化作用

采用溶剂热法合成了乙酸氧钛,其对碳酸二甲酯(DMC)与苯酚的酯交换合成碳酸二苯酯(DPC)的催化反应显示出了很好的催化效果.乙酸氧钛用量0.10 g时,苯酚转化率即达到47.8%,酯交换选择性在99.9%以上,仅检测到微量副产物苯甲醚.傅里叶变换红外光谱(FTIR)和固体核磁共振(13C NMR)等表征结果显示,乙酸氧钛在反应过程中首先与苯酚反应,苯氧基取代乙酸根生成苯氧基钛合物.实验结果表明,苯氧基钛合物作为实际催化剂参与DMC和苯酚的酯交换反应,并且重复使用效果良好.     

ICP—AES摄谱法的光谱分析检出限测定方法

本文分析了五种摄谱法检出限的测定方法,总结了其优缺点和可行性,并进行了实验,在比较的基础上。作者认为采用log(I_0/I_B)/-log C_0作图法,无论是从理论上,还是从实践上,都较其余四种方法优越,是一种值得推荐的方法。     

非晶硅碳薄膜发光二极管的效率分析

本文利用简单的能带结构模型,分析了非晶硅碳薄膜发光二极管的载流子注入、复合和输运过程,定量计算了器件的发光效率。在忽略器件结温影响的情形下,发现低场下器件的发光效率主要取决于空穴的注入效率,而在高场下则主要依赖于空穴的辐射复合效率,理论分析与实验结果相一致。在此基础上简要提出了提高器件发光特性的措施。     

Use of ferric-impregnated volcanic ash for arsenate (V) adsorption from contaminated water with various mineralization degrees

Ferric-impregnated volcanic ash (FVA) which consisted mainly of different forms of iron and aluminum oxide minerals was developed for arsenate (V) removal from an aqueous medium. The adsorption experiments were conducted in both DI water samples and actual water (Lake Kasumigaura, Japan) to investigate the effects of solution mineralization degree on the As(V) removal. Kinetic and equilibrium studies conducted in actual water revealed that the mineralization of water greatly elevated the As(V) adsorption on FVA. The experiment performed in DI water indicated that the existence of multivalence metallic cations significantly enhanced the As(V) adsorption ability, whereas competing anions such as fluoride and phosphate greatly decreased the As(V) adsorption. It is suggested that FVA is a cost-effective adsorbent for As(V) removal in low-level phosphate and fluoride solution. It was important to conduct the batch experiment using the actual water to investigate the arsenic removal on adsorbents.     

有机锡化合物催化甲基苯基碳酸酯歧化反应合成碳酸二苯酯

研究了不同配位基团的有机锡化合物对甲基苯基碳酸酯(MPC)歧化合成碳酸二苯酯(DPC)反应的催化性能.探究了电子效应和空间位阻对MPC歧化反应活性的影响,结果表明,有机锡化合物作为Lewis酸,与锡原子配位基团的吸电子效应和空间位阻影响相应催化剂的酸性从而影响其反应活性,电子效应的影响大于空间位阻的影响.氧化氢氧丁基锡[BuSnO(OH)]催化剂具有最好的催化性能,在BuSnO(OH)与MPC摩尔比为0.02,180℃及反应2.5 h条件下,MPC的转化率达到89.7%,DPC选择性为99.3%.     

复杂粒子预平衡发射的准直接反应模型

本模型提出了核内复杂粒子集团的准直接反应形成机制,给出了复杂粒子发射几率对准直接反应截面σ_s 及能量εβ的依赖关系。计算结果与实验拟合良好。     

Parametric blur estimation for blind restoration of atmospherically degraded images: Class G

Iterative methods are typically utilized for blind image restoration (BIR); however, they are relatively slow, uncertain, and occasionally ill-behaved. This study presents a non-iterative algorithm to estimate the parameters of point spread functions (PSFs), particularly, Class G. We propose a curve model to approximate the normalized spectrum amplitude of the original image in accordance with the decay law of the natural image spectrum. The blur PSF is estimated by comparing the original image spectrum with the degraded one. Then, the image is restored by applying the estimated PSF and the Wiener filter. Experimental results demonstrate that the proposed algorithm can obtain a more accurate PSF and reduce ringing artifacts compared with the existing algorithms. The quality of the restored images is enhanced significantly.     

环张力促进的叠氮-炔环加成反应

近年来,点击化学中的环张力促进的叠氮-炔环加成(SPAAC)反应由于具有高效快速、高选择性和生物正交性等优点被广泛用于生物医学和材料科学等多个领域。SPAAC反应不需要光、热、超声和催化剂等额外的刺激,反应的驱动力来源于高张力的活泼环状炔烃,因此合理设计环状炔烃是SPAAC反应的关键。本文详细归纳了不同环数目的环状炔烃的稳定性和反应活性,总结参与SPAAC的稳定环状炔烃,并讨论了它们参与SPAAC反应的二级反应速率常数。本文还介绍了目前应用广泛的代表性环状炔烃的制备方法研究进展。最后,对无铜催化的SPAAC的应用前景和存在的问题进行讨论和展望。