一种简单合成7-羟基-高异黄酮的催化方法

以间苯二酚和苯丙酸为原料,三氟化硼乙醚为催化剂合成了2',4'-二羟基二氢查尔酮(收率84%),再经过增碳成环得到7-羟基-高异黄酮(收率84%)。此法绿色简捷,生产成本较低。     

红外伪装涂料的性能及存在问题

详细论述了红外伪装涂料的作用机理和影响因素以及存在问题.     

水玻璃的固化机理及其提高耐水性途径分析

伴随环保要求的提升和人们环境意识的提高,水玻璃作为一种环境友好型粘结剂受到广大研究者以及消费者的垂青。但水玻璃因其自身的结构而导致的固化后耐水性差的问题尚未得到彻底的解决,不同的固化途径而产生的固化机理亦是琳琅满目,从而使水玻璃在其应用原理以及解决其相应的缺陷上受到阻碍。笔者对近几年来所研究的水玻璃固化机理以及提高其耐水性途径进行了详细的分析,以促进和拓宽水玻璃的改性研究及应用领域。     

Study of electrochemical hydrogen charge/discharge properties of FePO4 for application as negative electrodes in hydrogen batteries

We report the electrochemical hydrogen charge/discharge properties of electrodes containing crystalline and amorphous FePO₄ as active material in KOH electrolyte. Crystalline and amorphous FePO₄ were synthesized by an alcohol-assisted precipitation method, and the powders obtained were characterized by X-ray diffraction. X-ray photoelectron spectroscopy is used to investigate the mechanism of hydrogen charge/discharge behavior of FePO₄. The electrochemical hydrogen charge/discharge properties of electrodes containing crystalline and amorphous FePO₄ were investigated for potential application as negative electrodes in rechargeable hydrogen batteries. In galvanostatic discharge/charge mode at 25 °C, the crystalline FePO₄ showed a maximum discharge capacity of 109 mA h g⁻¹, while the amorphous FePO₄ showed a maximum discharge capacity of 81.4 mA h g⁻¹. The electrochemical kinetic properties, exchange current density, and proton diffusivity were calculated using linear polarization measurement and the potential-step method.     

拉挤型FRP管轴向压缩承载性能研究

针对单向纤维增强树脂基复合材料(FRP)压缩强度远低于其拉伸强度的问题,对影响拉挤FRP管轴向压缩承载力的一些因素进行研究,探讨提高拉挤FRP管轴向压缩强度的途径。结果表明,无端部约束情况下增加包裹对提高FRP管承载力效果不明显;端部约束可改变FRP管破坏形式,对提高其承载力效果显著;在端部约束情况下增加包裹也可有效提高FRP管承载力。     

Polymer brush coatings for combating marine biofouling

A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides. This review summarizes recent developments in marine antifouling polymer brushes and coatings that are tethered to material surfaces and do not actively release biocides. Polymer brush coatings have been designed to inhibit molecular fouling, microfouling and macrofouling through incorporation or inclusion of multiple functionalities. Hydrophilic polymers, such as poly(ethylene glycol), hydrogels, zwitterionic polymers and polysaccharides, resist attachment of marine organisms effectively due to extensive hydration. Fouling release polymer coatings, based on fluoropolymers and poly(dimethylsiloxane) elastomers, minimize adhesion between marine organisms and material surfaces, leading to easy removal of biofoulants. Polycationic coatings are effective in reducing marine biofouling partly because of their good bactericidal properties. Recent advances in controlled radical polymerization and click chemistry have also allowed better molecular design and engineering of multifunctional brush coatings for improved antifouling efficacies.     

Electrical properties and the role of inhomogeneities at the polyvinyl alcohol/n‐inp schottky barrier interface

In this work, we have investigated the electrical properties of Au/n‐InP contacts with a thin layer of polyvinyl alcohol (PVA) as an interlayer. The current–voltage (I–V) and capacitance–voltage (C–V) measurements are carried out in the temperature range of 175–425 K. The Au/PVA/n‐InP Schottky structure show nonideal behaviors and indicates the presence of a nonuniform distribution of interface states. The temperature dependent interface states densities (N_SS), ideality factor and barrier height are obtained. An abnormal decrease in zero‐bias barrier height (BH) and increase in the ideality factor ( ) with decreasing temperature have been explained on the basis of the thermionic emission theory with Gaussian distribution (GD) of the BHs due to the BH inhomogeneities. The experimental I–V characteristics of Au/PVA/n‐InP Schottky diode has revealed the existence of a double GD with mean BH values of ( ) of 1.246 and 0.899 eV and standard deviation ( ) of 0.176 and 0.137 V, respectively. Consequently, the modified conventional activation energy versus plot gives and Richardson constants ( ) and the values are 1.17 and 0.71 eV and 9.9 and 6.9 A/cm² K², respectively, without using the temperature coefficient of the BH. The effective Richardson constant value of 9.9 A/cm² K² is very close to the theoretical value of 9.4 A/cm² K² for n‐InP. The discrepancy between Schottky barrier heights estimated from I–V and C–V measurements is also discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39773.     

DNA‐Scaffolded Multivalent Ligands to Modulate Cell Function

We report a simple, versatile, multivalent ligand system that is capable of specifically and efficiently modulating cell‐surface receptor clustering and function. The multivalent ligand is made of a polymeric DNA scaffold decorated with biorecognition ligands (i.e., antibodies) to interrogate and modulate cell receptor signaling and function. Using CD20 clustering‐mediated apoptosis in B‐cell cancer cells as a model system, we demonstrated that our multivalent ligand is significantly more effective at inducing apoptosis of target cancer cells than its monovalent counterpart. This multivalent DNA material approach represents a new chemical biology tool to interrogate cell receptor signaling and functions and to potentially manipulate such functions for the development of therapeutics.     

Conjugated polymer mediated synthesis of nanoparticle clusters and core/shell nanoparticles

Two water soluble conjugated polymers, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and ammonium ion stabilized poly(phenylene vinylene) (P2), are found to be able to reduce noble metal ions to zero-valent metals via a direct chemical deposition technique. Au nanoparticle clusters can be obtained through reduction of Au³⁺ ions by PEDOT:PSS and the electronic coupling between them can be controlled by HAuCl₄ concentration. Core/shell Ag/polymer nanostructures are prepared from reduction of Ag⁺ ions by P2, which have a ppb detection limit for 4-MBA using surface-enhanced Raman spectroscopy (SERS). This conjugated polymer mediated synthesis of metal nanoparticles may open a new avenue for fabricating nanomaterials and nanocomposites with tunable optical properties that are dominated by their structure and electronic coupling between nanoparticles.     

Immobilization of pamidronic acids on the nanotube surface of titanium discs and their interaction with bone cells

Self-assembled layers of vertically aligned titanium nanotubes were fabricated on a Ti disc by anodization. Pamidronic acids (PDAs) were then immobilized on the nanotube surface to improve osseointegration. Wide-angle X-ray diffraction, X-ray photoelectron microscopy, and scanning electron microscopy were employed to characterize the structure and morphology of the PDA-immobilized TiO₂ nanotubes. The in vitro behavior of osteoblast and osteoclast cells cultured on an unmodified and surface-modified Ti disc was examined in terms of cell adhesion, proliferation, and differentiation. Osteoblast adhesion, proliferation, and differentiation were improved substantially by the topography of the TiO₂ nanotubes, producing an interlocked cell structure. PDA immobilized on the TiO₂ nanotube surface suppressed the viability of the osteoclasts and reduced their bone resorption activity.