Synthesis and Characterization of Pindolol Imprinted Polymer

Molecularly imprinted polymers (MIPs) are capable of recognizing a particular molecule in presence of others due to the selective cavities on it and thus are known as plastic antibodies. Pindolol (PDL) is a synthetic beta-adrenergic receptor blocking agent and widely used for the treatment of hypertension, cardiac arrhythmia and angina pectoris. Using a combinatorial method PDL imprinted polymers were prepared with three functional monomers viz., itaconic acid, 4-vinylpyridine and methacrylic acid by thermal initiated bulk polymerization technique using ethylene glycol dimethacrylate, 2, 2′-azobisisobutyronitrile and acetonitrile as crosslinker, initiator and solvent respectively. Among the three, PDL-itaconic acid MIP shows the best binding capacity. The PDL imprinted polymer was characterized by FTIR spectra and morphology was studied by SEM images. The binding parameters of MIP and non-imprinted polymer (NIP) were compared by the Freundlich and Langmuir adsorption isotherms.     

Atomistic Investigation of the Role of Grain Boundary Structure on Hydrogen Segregation and Embrittlement in α-Fe

Material strengthening and embrittlement are controlled by complex intrinsic interactions between dislocations and hydrogen-induced defect structures that strongly alter the observed deformation mechanisms in materials. In this study, we reported molecular statics simulations at zero temperature for pure α-Fe with a single H atom at an interstitial and vacancy site, and two H atoms at an interstitial and vacancy site for each of the 〈100〉, 〈110〉, and 〈111〉 symmetric tilt grain boundary (STGB) systems. Simulation results show that the grain boundary (GB) system has a smaller effect than the type of H defect configuration (interstitial H, H-vacancy, interstitial 2H, and 2H-vacancy). For example, the segregation energy of hydrogen configurations as a function of distance is comparable between symmetric tilt GB systems. However, the segregation energy of the 〈100〉 STGB system with H at an interstitial site is 23 pct of the segregation energy of 2H at a similar interstitial site. This implies that there is a large binding energy associated with two interstitial H atoms in the GB. Thus, the energy gained by this H-H reaction is ~54 pct of the segregation energy of 2H in an interstitial site, creating a large driving force for H atoms to bind to each other within the GB. Moreover, the cohesive energy values of 125 STGBs were calculated for various local H concentrations. We found that as the GB energy approaches zero, the energy gained by trapping more hydrogen atoms is negligible and the GB can fail via cleavage. These results also show that there is a strong correlation between the GB character and the trapping limit (saturation limit) for hydrogen. Finally, we developed an atomistic modeling framework to address the probabilistic nature of H segregation and the consequent embrittlement of the GB. These insights are useful for improving ductility by reengineering the GB character of polycrystalline materials to alter the segregation and embrittlement behavior in α-Fe.     

基于声道效应的宽带声单向传输结构

0引言电子二极管以及热二极管等人造器件先后实现了对不同形式的能量进行整流控制,它们的出现对基础科学研究和先进技术变革产生了广泛影响[1]。声波作为一种经典的能量传播形式,至今尚未有成熟的人工器件对其进行整流。然而,近年来不断的探索研究,对声能流的调控取得了不少进展[2,3]。梁等人[3]提出超晶格与强非线性媒质组成的声二极管模型,首次实现将声能流限制在单一方向的     

基于民用移动通信信号的经典TDOA定位算法分析

基于民用移动通信信号的无源雷达系统具有隐蔽性好、反隐身能力及抗干扰能力强、系统简单可靠等优点,近年来受到各国的重视,得到了较快的发展。针对基于民用移动通信信号的无源定位系统中Chan氏算法和Taylor级数算法的实现过程展开分析研究,并在不同的基站配置下,与其相应的定位精度卡拉美罗下限进行了比较,发现当测量误差的均方差较小时,利用Chan氏算法和Taylor级数算法均可以逼近卡拉美罗下限。     

Unique visualization of multiply oriented lattice structures using a continuous wavelet transform

The application of continuous wavelet transformation in the phase field crystal model has yielded excellent results for the crystal lattice orientation and grain boundaries with different misorientation angles [H.M. Singer, I. Singer, Phys. Rev. E 74 (2006) 031103]. However, we show here that the orientation map from this simple method cannot distinguish symmetric orientations using a single convolution template. By introducing additional rotational templates, the grain orientation can be uniquely visualized in two and three dimensions.     

Prediction of tender price index directional changes

A multivariate discriminant analysis is described, aimed at predicting the direction of changes in the Hong Kong tender price index by utilizing the patterns of change in eight leading economic indicators. Two discriminant functions are derived which distinguish between ‘upward’, ‘constant’ and ‘downward’ index trends with a high degree of success. The predictive power of the discriminant model is tested by means of a simulated ex post holdout sample of eight index values. By comparing the group centroids, seven of the cases are correctly classified. The hit rate of the ‘upward’ and ‘constant’ groups is 100%, while the ‘downward’ group has a hit rate of 75%, suggesting the ‘downward’ trend to be a more difficult movement to predict. Despite this, the overall predictive results are considerably better than those that would have occurred by chance alone.     

通过式固相萃取柱结合QuEChERS前处理技术-液相色谱串联质谱法快速测定熟肉食品中4种β2-受体激动剂残留

目的 建立通过式固相萃取柱结合前处理技术-液相色谱串联质谱法快速测定熟肉制品中克伦特罗、莱克多巴胺、沙丁胺醇、特布他林4种常见β2-受体激动剂类兽药残留的分析方法.方法 熟肉制品采用5％三氯乙酸酸解,NaCl盐析乙腈萃取,正己烷除脂后经通过式固相萃取柱和QuEChERS净化,超高效液相色谱-串联质谱于电喷雾正离子源(E...     

Transparent broadband microwave metamaterial absorber with thermal insulating and soundproof

Nowadays, multi-functional materials are desperately required for adapting the complex environment, which urges us to take more factors into consideration. Here, we proposed a broadband microwave absorber with multi-functionality such as optically transparent, thermal insulating and soundproof properties. Using indium tin oxide(ITO) based metamaterial, the device can achieve above 90% microwave absorption from 5.6 GHz to 23 GHz(cover X and Ku band). Moreover, with designed vacuum structure inside, the device is thermal insulating and soundproof. These multi-functional advantages give the absorber more flexibility in electromagnetic shielding and stealth application, which can be potentially applied in windows related industry.