Capillary electrochromatographic separation of enantiomers on chemically bonded type of cellulose derivative chiral stationary phases with a positively charged spacer

Positively charged chiral stationary phases (CSPs) were prepared for capillary electrochromatography (CEC) separation of enantiomers by chemically immobilizing cellulose derivatives onto diethylenetriaminopropylated silica (DEAPS) with tolylene-2,4-diisocyanate (TDI) as a spacer reagent. Anodic electroosmotic mobility was observed in both nonaqueous and aqueous mobile phases due to the positively charged amines on the surface of the prepared CSPs. For comparison, the traditionally used 3-aminopropyl silica (APS) was also adopted as the base material instead of DEAPS to prepare CSP. It was observed that the EOF on the DEAPS-based CSP was 18%-60% higher than that on the APS-based CSP under nonaqueous mobile phase conditions. Separation of enantiomers in CEC was performed on the positively charged CSPs with the nonaqueous mobile phases of pure ethanol or mixture of hexane-alcohol and the aqueous phases of acetonitrile-water or 95% ethanol. Fast separation of enantiomers was achieved on the newly prepared CSPs.     

The Association of Triton X Surfactants with β-Cyclodextrin. An Isothermal Titration Calorimetry Study

The association with -cyclodextrinof a series of Triton X surfactants with differentethylene oxide (EO) chain lengths was studied byisothermal titration calorimetry at 298.15 K. Theresults agree with a 1:1 association model.Association constants and changes in Gibbs freeenergies, enthalpies and entropies were derived forthe association process. Association of thesesurfactants with -cyclodextrin have favorableenthalpy changes and unfavorable entropy changes. Theshorter the EO chain of the surfactant, the greaterthe association constant with -cyclodextrin.     

Depth profiles of Ag nanoparticles in silicate glass

Silver nanoparticle composite glass has been synthesized by ion exchange and a subsequent thermal treatment method. Transmission electron microscopy (TEM) and ultraviolet-visible spectrometry were used to study the depth profiles of Ag nanoparticles in silicate glass. Results indicate that Ag nanoparticles are nearly spherical in shape with a single-crystalline structure. Also, the volume fraction of Ag nanoparticles is very high in the surface layer of 5 μm, and then decreases slowly across the depth of 30 μm, thereafter the volume fraction reduces quickly to zero at the depth of 100 μm. The plasmon resonance bi-absorptions in the surface layer of the annealed specimen at 600 °C can be attributed to bi-modal distributions of Ag nanoparticles in the layer. The bi-modal distributions can be explained by the Ostwald ripening theory. PACS 81.05.Pj; 81.07.-b; 68.37.Lp     

含有萘酰亚胺的菁染料太阳能电池敏化剂的合成

通过Click反应把萘酰亚胺化合物连接到含有醛基的吲哚上,再通过醛基和吲哚碘盐的Knoevenagel缩合反应合成出带有萘酰亚胺部分的菁染料,用NMR、MS、元素分析、UV-Vis等方法对其结构和性能进行了表征和测试。     

投影显示亮度均匀性稳健校正方法

随着投影仪的发展,其显示质量越来越受到人们关注.投影显示中普遍存在亮度不均匀性问题,且大部分高灰度图像在亮度校正后易出现饱和.而一般的剪切法会极大地降低像面均匀性.为解决这个问题,基于投影仪相机系统建立系统光度学模型,在传统线性映射方法的基础上提出了一种亮度不均匀性校正的非线性稳定算法.实验表明,采用的投影仪在校正前其图像显示亮度从中心到边缘下降了近50%,像面不均匀性的相对均方根误差(RRMS)为17.7%;而饱和图像校正后像面的RRMS为1.69%,几乎达到了与未饱和图像(1.55%)相同的校正精度,同时基本保持了显示图像的平均亮度水平.     

细胞色素bc1复合物结晶的偏振拉曼光谱研究

本文报道了用５１４．５ｎｍ和４１３．１ｎｍ激光激发的细胞色素ｂｃ１复合结日 的偏振显微共振拉曼光谱和用１０６４ｎｍ激光激发的近红外傅里叶变换偏振拉曼光谱,已观察到不同结晶取向和偏振的影响。结果表明,这些取向排列和偏振的影响和分子的对称性质和结晶的三维结构有关。综可能随着三维结构中子单元和的中心的部位不同而改变,其对称性的不同与三不对称排列有关,也可归因子蛋白南环境电学上的不对称性。     

Organic thin-film transistors with polymeric gate insulators

Copper phthalocyanine (CuPc) thin-film transistors (TFTs) have been fabricated using spin-coated polymeric gate insulators, including polymethyl methacrylate (PMMA) and a novel poly(methylmethacrylate-co-glycidylmethacrylate) (P(MMA-co-GMA)). These devices behaved fairly well and showed satisfactory p-type electrical characteristics. The transistor with P(MMA-co-GMA) gate insulator showed higher field-effect mobility, μ_FET = 1.22 × 10⁻² cm²/V s, larger on/off current ratio, I_on/I_off = 7 × 10³ and lower threshold voltage, V_T = −8 V, compared with the transistor with PMMA gate insulator (μ_FET = 5.89 × 10⁻³ cm²/V s, I_on/I_off = 2 × 10³ and V_T = −15 V). The higher mobility of CuPc on P(MMA-co-GMA) was attributed to better ordering and enhanced crystallinity within the CuPc film and the better CuPc/P(MMA-co-GMA) interface, as observed by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements. The correlation between the structural properties and the device performance of CuPc films grown on different polymeric gate insulators is discussed.     

微差爆破振动波速度峰值-位移分布特征的延时控制

为了通过振动波传播规律研究微差爆破延时控制,改善爆破振动和提高爆炸能利用,选取普通雷管和澳瑞凯高精度雷管进行不同段别延期起爆对比实验,试爆过程对振动波测振。基于振动波函数优化理论基础,对实测数据和波状谱处理分析,总结了不同微差时间下振动波传播规律及速度峰值、主频、频带能量、总能量等变化特征,根据该特征发现振动波速度图谱和该速度积分所得位移图谱中两者最大值对应时间点相同。依据此速度峰值-振动位移分布特征,对某实测简单振动波进行高斯多峰拟合,结果表明:该波段能量最大化时间点为60 ms左右,振动最小的时间点为25 ms左右。     

Electric-magnetic-force characteristics of rare earth barium copper oxide superconductor high-field coils based on screening effect and strain sensitivity

Rare earth barium copper oxide (REBCO) is the most researched and commercialized second-generation high-temperature superconducting material. Due to the anisotropic structure, strong deformation sensitivity, and central field errors caused by screening current effects, it is still a challenge for commercialization applications. In this study, the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes, and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships. Then, a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain. Finally, the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils, and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated, respectively. The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes, but causes a significant enhancement in the force field distribution. In the presence of 0.5% mechanical strain, the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%, respectively, with a nearly 5 times increase in the peak stress. The screening current makes the current field distribution inside the coil improve by about 10 times. The screening current induced magnetic field can reach up to 0.8 T, making the relative error of the high-field coil center up to 7.8%.     

A hidden mode observation approach to finite-time SOFC of Markovian switching systems with quantization

Nonlinear Dynamics - This paper investigates the finite-time static output feedback control of Markovian switching systems, where quantization effects are taken into consideration from plant to...