优化全日制化学教育硕士培养模式的探讨

全日制教育硕士（学科教学·化学）研究生培养是一个具有挑战性的、全新的研究课题。从"目标定位""课程优化"和"实践提升"3个方面对化学教育硕士培养进行探讨。在"目标定位"上应培养化学教育硕士具有较强的化学课堂教学能力和教研能力，在"课程优化"上，应优化更具功能化和结构化的课程体系，在"实践提升"上应搭建基于科学态磨课的全类型、全环节的实践平台。     

双波长分光光度法测定湿法炼锌净化液中的痕量锗

选择水杨基荧光酮－乳化剂ＯＰ－盐酸为显色体系，应用双波长分光光度法扣除硫酸锌的基体干扰，不分离直接测定了湿法炼锌过程中硫酸锌净化液中的痕量锗。测定范围在０－４０ｍｇ／Ｌ。本法应用于株洲冶炼厂锌净化液中锗的测定，结果与该厂长期的萃取－比色法结果相吻合，而测定速度较萃取－比色法至少提高了一倍。     

磁性纳米包覆微球的制备和磁性表征

以胶体球形粒子为基体发展起来的纳米包覆(nano鄄coating)技术近来引起人们的极大兴趣,这种纳米包覆技术得到的产物常常被称为核壳粒子(core鄄shellparticles)。这种包覆一般是将纳米颗粒直接吸附在核微球上,或者包覆材料控制沉淀在核微球上[1,2]。这些复合微球常常展现出独特的光、电、力学、化学、催化等性质,因而具有广泛的研究和应用前景[3~7]。近十几年来,用做磁感应成像的超顺磁材料得到了深入的研究[4]。一方面,磁性颗粒的尺寸、电荷和表面成分对其应用有很大影响[8,9],另一方面,材料的磁学性质又主要取决于磁颗粒的大小[10]。Xu和Lindlar制备了含超顺磁颗粒的聚合物胶体颗粒,被用于构建超顺磁性的光子晶体[11,12]。在聚合物微粒上包覆氧化铁颗粒通常采用表面沉淀或表面改性官能团诱导反应包覆的方法。但这些方法不能很好控制复合微粒的均一性和表面平整性;Caruso的层鄄层包覆法(Layer鄄byLayer)虽然实现了磁性颗粒包覆[13],然而这种方法非常繁琐而不利于广泛应用。本文报道了一种新的合成磁性包覆颗粒的方法,即以聚合物微球为基核,通过非均相种子生长法包覆磁性纳米颗粒,并研究了...     

Enhancement of signal-to-noise level by synchronized dual wavelength modulation for light emitting diode fluorimetry in a liquid-core-waveguide microfluidic capillary electrophoresis system

The signal-to-noise level of light emitting diode (LED) fluorimetry using a liquid-core-waveguide (LCW)-based microfluidic capillary electrophoresis system was significantly enhanced using a synchronized dual wavelength modulation (SDWM) approach. A blue LED was used as excitation source and a red LED as reference source for background-noise compensation in a microfluidic capillary electrophoresis (CE) system. A Teflon AF-coated silica capillary served as both the separation channel and LCW for light transfer, and blue and red LEDs were used as excitation and reference sources, respectively, both radially illuminating the detection point of the separation channel. The two LEDs were synchronously modulated at the same frequency, but with 180°-phase shift, alternatingly driven by a same constant current source. The LCW transferred the fluorescence emission, as well as the excitation and reference lights that strayed through the optical system to a photomultiplier tube; a lock-in amplifier demodulated the combined signal, significantly reducing its noise level. To test the system, fluorescein isothiocyanate (FITC)-labeled amino acids were separated by capillary electrophoresis and detected by SDWM and single wavelength modulation, respectively. Five-fold improvement in S/N ratio was achieved by dual wavelength modulation, compared with single wavelength modulation; and over 100-fold improvement in S/N ratio was achieved compared with a similar LCW-CE system reported previously using non-modulated LED excitation. A detection limit (S/N = 3) of 10 nM FITC-labeled arginine was obtained in this work. The effects of modulation frequency on S/N level and on the rejection of noise caused by LED-driver current and detector were also studied.     

Surface-grafted polystyrene beads with comb-like poly(ethylene glycol) chains: preparation and biological application

We prepared surface-grafted polystyrene (PS) beads with comb-like poly(ethylene glycol) (PEG) chains. To accomplish this, conventional gel-type PS beads (35-75 microm) were treated with ozone gas to introduce hydroperoxide groups onto the surface. Using these hydroperoxide groups, poly(methyl methacrylate) (PMMA, Mn= 22,000-25,000) was grafted onto the surface of the PS beads. The ester groups of the grafted PMMA were reduced to hydroxyl groups with lithium aluminum hydride (LAH). After adding ethylene oxide (EO) to the hydroxyl groups, we obtained the PS-sg-PEG beads, which had a rugged surface and a diameter of 80-150 microm. We could obtain several kinds of the PS-sg-PEG beads by controlling the chain lengths of the grafted PMMA and the molecular weights of the PEG chains. The grafted PEG layer was about 30-50 microm thick, which was verified from the cross-sectioned views of the fluorescamine-labeled beads. These fluorescence images proved that the beads possessed a pellicular structure. Furthermore, we found that the surface-grafted PEG chains had the characteristic property of reducing non-specific protein adsorption on the beads.     

Comparative analysis of affine scaling algorithms based on simplifying assumptions

We analyze several affine potential reduction algorithms for linear programming based on simplifying assumptions. We show that, under a strong probabilistic assumption regarding the distribution of the data in an iteration, the decrease in the primal potential function will be with high probability, compared to the guaranteed(1). ( 2n is a parameter in the potential function andn is the number of variables.) Under the same assumption, we further show that the objective reduction rate of Dikin's affine scaling algorithm is with high probability, compared to no guaranteed convergence rate.Research supported in part by NSF Grant DDM-8922636.     

Use of a Dual-Marker Form of Analysis to Estimate Binding Constants Between Receptors and Ligands by Affinity Capillary Electrophoresis

This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described.     

非线性含磁芯线圈的PSpice模拟

 将感应加速腔的磁芯回路视为一段单匝的非线性电感线圈,利用PSpice的一些通用元器件组成的子电路对含有磁芯的非线性线圈进行模拟，使其具有饱和、磁滞及频率损耗等非线性特征。通过一些直观的参数设置，可使线圈模型适用于不同的频率范围。介绍了利用线圈模型对直线感应加速器加速组元系统的模拟，得到了与实验相符合的结果。     

Native agarose gel electrophoresis and electroelution: A fast and cost‐effective method to separate the small and large hepatitis B capsids

Hepatitis B core antigen (HBcAg) expressed in Escherichia coli is able to self‐assemble into large and small capsids comprising 240 (triangulation number T = 4) and 180 (triangulation number T = 3) subunits, respectively. Conventionally, sucrose density gradient ultracentrifugation and SEC have been used to separate these capsids. However, good separation of the large and small particles with these methods is never achieved. In the present study, we employed a simple, fast, and cost‐effective method to separate the T = 3 and T = 4 HBcAg capsids by using native agarose gel electrophoresis followed by an electroelution method (NAGE‐EE). This is a direct, fast, and economic method for isolating the large and small HBcAg particles homogenously based on the hydrodynamic radius of the spherical particles. Dynamic light scattering analysis demonstrated that the T = 3 and T = 4 HBcAg capsids prepared using the NAGE‐EE method are monodisperse with polydispersity values of ～15% and ～13%, respectively. ELISA proved that the antigenicity of the capsids was not affected in the purification process. Overall, NAGE‐EE produced T = 3 and T = 4 capsids with a purity above 90%, and the recovery was 34% and 50%, respectively (total recovery of HBcAg is ～84%), and the operation time is 15 and 4 times lesser than that of the sucrose density gradient ultracentrifugation and SEC, respectively.     

Experimental and numerical investigation of aramid fibre reinforced laminates subjected to low velocity impact

The low velocity impact performance of domestic aramid fibre reinforced laminates is investigated experimentally and numerically. Laminates with different thicknesses are impacted by drop-weight test machine under different impact energies. The time histories of impact force are recorded and ultrasonic C-scan technology is used to inspect the internal damage of the laminates. Numerical simulation is conducted using finite element method (FEM), taking into account both intralaminar and interlaminar damage. The intralaminar damage model is based on the continuum damage mechanics (CDM) approach, which consists of the strain-based Hashin failure criteria and the exponential damage evolution law, and considers the nonlinear shear behaviour of the material. The interlaminar damage is simulated by interface elements with cohesive zone model. The numerical results show good agreements with the experiments, thus verifying the validity of the presented numerical model.