Interface characteristics of thin liquid films in a charged lubricated contact

The interface characteristics of liquid films confined within a nanogap between a steel ball and a smooth glass disk after exposing to an external electric field (EEF) are reported in the paper. The emergence of micro‐bubbles induced by the EEF has been found to be closely related with the electric current flow at both a positive EEF and a negative EEF. The polarity effect of the variation in the electric current flowing through a polar liquid film over time is more pronounced than that through a nonpolar liquid film. The surface of the contacting pair with the polar liquid film confined after the removal of the EEF is more severely damaged at a negative EEF, while no indication of damage has been observed on the surface contacting the nonpolar liquid film at either polarity. The bubbles generated under a positive EEF can collapse more readily than those generated under a negative EEF. Different mechanisms of these experimental phenomena have been discussed in the paper. Copyright © 2014 John Wiley & Sons, Ltd.     

Oriented immobilisation of histidine-tagged protein and its application in exploring interactions between ligands and proteins

A method based on reaction with a diazonium salt was developed to immobilise oriented His-tagged protein onto silica gel. The binding efficiency of the phenylamine-group-coated gel was determined to be 65 %, providing a binding capacity of His-tagged protein up to the gram level. Using His-tagged β₂-adrenoceptor (β₂-AR) as a probe, we developed a new mathematical model to elucidate the interactions between the receptor and five ligands (methoxyphenamine, terbutaline, salbutamol, tulobuterol and fenoterol). These drugs proved to only have one type of binding site on the immobilised β₂-AR, yielding higher association constants and numbers of binding sites than random attachment assays. The association constants determined by the new model positively correlated to the values from a radioligand binding method, with a regression equation of y?=?1.75x???7.18 and a correlation coefficient of 0.9807. The oriented method resulted in a high binding capacity and quantitative immobilisation of the His-tagged protein. The proposed model can be used to determine the interactions between the ligands and the immobilised protein with the advantages of drug and time saving.

人工神经网络在示波计时电位法中的应用

研究了误差反传神经网络和小波变换在示波计时电位测定中应用的可能性。对Ｐｂ２ ＋ 等无机离子测定的实验结果表明： 人工神经网络可较好地用于高次微分和经小波变换处理后的示波计时电位测定。 与经典的示波测定方法相比较, 该法基本上消除了人为误差的影响, 提高了分析速度和分析结果的可靠性。     

Viscoelasticity of Shear Thickening Fluid Based on Silica Nanoparticles Dispersing in 1-butyl-3-methylimidizolium Tetrafluoroborate

The viscoelasticity of shear thickening fluid (STF), a crucial property in the protective composite applications, with different silica nanoparticle concentrations in ionic liquid, 1-butyl-3-methylimidizolium tetrafluoroborate ([C₄min]BF₄), was studied at different temperatures and with shear frequencies through oscillatory shear, respectively. All STFs present strain thickening behavior. With increasing silica nanoparticle concentration, the critical shear strain for the onset of strain thickening decreased, while the complex viscosity, storage modulus, and loss modulus increased significantly. The critical shear strain increased with an increase of temperature, while the complex viscosity, storage modulus, and loss modulus decreased notably. The critical shear strain was constant with increasing the frequency of strain, while the complex viscosity decreases slightly. The storage modulus and loss modulus were independent with frequency in the strain thickening region. Nanoparticle clusters leading to strain thickening were demonstrated. The viscoelastic response of STFs to varying silica nanoparticle content, temperature, and frequency investigated here will help to design the specific application of STFs in soft protective composites and damping devices.     

联合载体用于改善白藜芦醇固体分散体性能

通过载体聚乙烯吡咯烷酮(PVPk29/32)和羟丙基甲基纤维素(HPMC),采用溶剂法制备白藜芦醇(Res)二元及三元固体分散体。 用傅里叶变换红外光谱(FTIR)、调制式差示扫描量热(MDSC)和X射线粉末衍射(XRD)等技术手段来表征Res二元和三元固体分散体并考察其溶出度。 FTIR结果显示,Res与PVPk29/32及HPMC均存在氢键相互作用;溶出结果表明,二元和三元固体分散体均能提高药物的溶出度。 而XRD和MDSC结果表明,三元固体分散体的相容性优于二元固体分散体;3个月的加速实验(40 ℃,75%RH(relative humidity))中,XRD、MDSC及体外溶出结果表明,Res三元固体分散体的稳定性优于Res二元固体分散体。 HPMC的加入可以改善Res三元固体分散体的溶出及稳定性。     

Organized assemblies in bolaamphiphile/oppositely charged conventional surfactant mixed systems

Five ionic bolaamphiphiles were synthesized and the aggregation behavior of bola single systems and bola/oppositely charged conventional surfactant mixed systems was studied. Small spherical vesicles were formed in all these mixed systems revealed by transmission electron microscopy (TEM). Variation of the structure of the hydrophobic chain of bolaamphiphiles has great influences on the vesicle formation ability. Vesicles were also found in the single system of a carboxylate bolaamphiphile, which was attributed to the hydrolysis of the bolaamphiphile. The results of FT-IR and X-ray diffraction (XRD) showed that bolaamphiphiles spanned through the vesicle membranes in these mixed systems. Super thermostability of the vesicles in this kind of mixed system was also investigated.     

Study of a shear thickening fluid: the suspensions of monodisperse polystyrene microspheres in polyethylene glycol

The monodisperse polystyrene (PS) microspheres were prepared by dispersion polymerization. The rheological properties of shear thickening fluid (STF) based on PS microspheres dispersing in polyethylene glycol with different concentrations were studied through the steady and oscillatory shear at different temperatures, respectively. All suspensions successively present the first shear thinning, the shear thickening, and the second shear thinning. The experimental results indicate that the shear thickening behavior of STF is controlled by the concentration of PS microspheres and temperature, as changed from continuous shear thickening (CST) to discontinuous shear thickening (DST) with increasing solid content or decreasing temperature. The STF is affected by shear rate, temperature, and the viscosity of the dispersed medium, and it is reversible absolutely and presents transient response ability. Both CST and DST behave as dilatancy. The PS microsphere aggregations formed under shear stress may result in the shear thickening in STFs.     

地热水驱动双级有机闪蒸循环热性能研究

以R601、R601a、R123、R227ea、R245fa、R600、R600a、R236ea为循环工质,以150℃地热水作为热源温度,建立了双级OFC系统模型,对系统的热性能进行了研究,同时揭示了不同工质的低压级最优闪蒸压力.结果 表明,当循环工质为R601,高压级闪蒸压力为630.53 kPa时,双级OFC的净输...     

A Novel Structure of Bipyridine Coordinated with Copper (II): [Cu(bipy) (H2O)3] · (NO3)2

The crystal structure of the mononuclear copper (II) complex containing a 2,2′-bipyridine and three water molecules, [Cu(bipy) (H₂O)₃]. (NO₃)₂, is reported. The copper coordination polyhedron is a five-coordinated distorted pyramid.