激光溅射Ni等离子体与气相CH3OH团簇的反应

用激光溅射 分子束技术研究了气相中Ni的等离子体与甲醇分子团簇的反应 .观察到Ni+ (CH3 OH) n、NiO+ (CH3 OH) n、H+ (CH3 OH) n、H3 O+ (CH3 OH) n 四个种类的团簇正离子和CH3 O-(CH3 OH) n(n≤ 2 5 )一种团簇负离子 .详细考察了激光烧蚀等离子体作用于脉冲分子束的不同位置时 ,对团簇产物种类和团簇尺寸大小的影响 .发现NiO+ (CH3 OH) n 是由Ni+ (CH3 OH) n 团簇内的脱甲烷反应生成的 ,而H+ (CH3 OH) n、H3 O+ (CH3 OH) n主要是激光等离子体中的电子与甲醇团簇碰撞电离产生的     

Monte Carlo simulation of the dynamic evolution ofbinary lamellar eutectic in directional solidification

The dynamic evolution of the lamellar eutectic of binary alloys in directional solidification is studied in detail using the Monte Carlo technique. The simulated results can be summarized into two aspects: ({1}) the lamellar spacing λ is found to be inversely proportional to the chemical potential difference Δμ, predicting a linear relationship between the kinetic supercooling ΔT_k and total supercooling at the solid/liquid (S/L) interface; (2) as the solidifying velocity R is low, the dynamic product λ^{2}R shows a considerable dependence on temperature gradient G_T in the liquid in front of the S/L interface, although this dependence becomes much weaker at a high R.     

In vitro degradation and release behavior of porous poly(lactic acid) scaffolds containing chitosan microspheres as a carrier for BMP-2-derived synthetic peptide

To develop a novel tissue engineering scaffold with the capability of controlled releasing BMP-2-derived synthetic peptide, porous poly(lactic acid)/chitosan microspheres (PLA/CMs) composites containing different quantities of chitosan microspheres were prepared by a thermally induced phase separation method. FTIR analysis revealed that there were strong hydrogen bond interactions between the PLA and chitosan component. Introduction of less than 30% CMs (on PLA weight basis) did not remarkably affect the morphology and porosity of the PLA/CMs scaffolds. The compressive strength of the composite scaffolds increased from 0.48 to 0.66 MPa, while the compressive modulus increased from 7.29 to 8.23 MPa as the microspheres' contents increased from 0% to 50%. In vitro degradability investigation indicated that the dissolution of chitosan component was preferential than PLA matrix and the inclusion of CMs could neutralize the acidity of PLA degradation products. Compared with the rapid release from CMs, the synthetic peptide was released from PLA/CMs scaffolds in a temporally controlled manner, mainly depending on the degradation of PLA matrix. The promising microspheres based scaffold release system can be used to deliver bioactive factors for a variety of non-loaded bone regeneration and tissue engineering application.     

Highly sensitive sensor for detection of NADH based on catalytic growth of Au nanoparticles on glassy carbon electrode

In this work, an electrochemical dihydronicotinamide adenine dinucleotide (NADH) sensor based on the catalytic growth of Au nanoparticles (Au NPs) on glassy carbon electrode was developed. Catalyzed by Au NPs immobilized on pretreated glassy carbon electrode, the reduction of AuCl₄ ^? in the presence of hydroquinone and cetyltrimethyl ammonium chloride led to the formation of enlarged Au NPs on the electrode surface. Spectrophotometry and high-resolution scanning electronic microscope (SEM) analysis of the sensor morphologies before and after biocatalytic reaction revealed a diameter growth of the nanoparticles. The catalytic growth of Au NPs on electrode surface remarkably facilitated the electron transfer and improved the performance of the sensor. Under optimal conditions, NADH could be detected in the range from 1.25?×?10^?6 to 3.08?×?10^?4 M, and the detection limit was 2.5?×?10^?7 M. The advantages of the proposed sensor, such as high precision and sensitivity, fast response, low cost, and good storage stability, made it suitable for on-line detection of NADH in complex biological systems and contaminant degradation processes.

A selective chemosensor for detection of Ag(I) and Cu(I) based on an acenaphthoquinone derivative and its complexes

A new Schiff base, acenaphthoquinone bis(diphenylmethlenehydrazone) (L), was synthesized and employed as a chemosensor for detecting Ag(I) and Cu(I). Experimental results showed that the chemosensor exhibited high selectivity and sensitivity. The sensitivity of the chemosensor for Ag(I) or Cu(I) was not affected by other metal ions, such as Ni(II), Nd(III), Zn(II), Fe(III), Cu(II), Na(I), La(III), K(I), and Co(II). Complexes 1 and 2 were synthesized by coordination of L with Ag(I) and Cu(I), respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. They had the same space group P2₁/c. Based on theoretical calculation, mechanism of the chemosensor detecting Ag(I) and Cu(I) was suggested.     

Enhanced orientation of PEO polymer chains induced by nanoclays in electrospun PEO/clay composite nanofibers

Polymer fibers composed of poly(ethylene oxide) (PEO) and nanoclay were fabricated by electrospinning. The morphology of the composite nanofibers was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), which showed aligned nanoclays in the fibers. Polarized Fourier transform infrared (FT-IR) spectroscopy revealed that the PEO chains in the composite fibers exhibit a higher degree of orientation than that in PEO nanofibers containing no nanoclay. It is believed that spatial confinement is present in the electrospun nanofibers, which results in the enforcement of the mutual restriction. The anisotropic hierarchical nanostructure may have potential applications in optics, mechanical materials, and biomedical materials for cell culture.     

多相催化反应原位红外系统及其应用

设计和建立了一套能耐高温的用于多相催化反应研究的原位红外系统，反应温度从室温到１１５０Ｋ，系统真空为１．０＊１０＾５－１．０－１０＾－４Ｐａ，红外光谱检测范围为４８００－２００ｃｍ＾－１。此系统扩展了原仪器的功能，提高了仪器利用率和效率。     

Silicon Carbide Supported Palladium‐Iridium Bimetallic Catalysts for Efficient Selective Hydrogenation of Cinnamaldehyde

Selective hydrogenation of α,β‐unsaturated carbonyls into saturated carbonyls is important to obtain remunerative products. However, it is still a challenge to achieve high activity and selectivity under mild conditions. Herein, Pd, Ir and bimetallic Pd‐Ir nanoparticles were uniformly deposited with high dispersity on the surface of SiC by a facile impregnation method, respectively. The as‐prepared Pd/SiC catalysts efficiently hydrogenate cinnamaldehyde to hydrocinnamaldehyde at room temperature and atmospheric pressure, and the activity of Pd/SiC is observed further enhanced by adding Ir component (conversion of 100%). In addition, the dependence of Pd‐Ir catalyst activity on Pd/Ir molar ratio confirms a synergistic effect between Ir and Pd, which originates from the electron transfer between Pd and Ir.     

L—组氨酸和色氨酸三元体系中稀土（Ⅲ）,钙（Ⅱ）的化学形态

在模拟生理条件下（３７℃,Ｉ＝０．１５ｍｏｌ／ＬＮａＣｌ）,用ｐＨ电位滴定与计算机模拟计算相结合的方法研究了镨（Ⅲ）、钆（Ⅲ）、铽（Ⅲ）、镱（Ⅲ）４ｔｋｈ ｔｑｄ ｆｆｆｆｙｂ ｂｂ ｔ ｑｇｈ （Ⅱ）、锌（Ⅱ）离子在Ｌ－组氨酸、色氨酸三元体系中的化学形态。讨论了稀土（Ⅲ）、钙（Ⅱ）和锌（Ⅱ）的物种分布特点。     

In situ encapsulation of laccase in nanofibers by electrospinning for development of enzyme biosensors for chlorophenol monitoring

A biosensor based on Trametes versicolor laccase (Lac) was developed for the determination of phenolic compounds. The biosensor was prepared by in situ electrospinning of a mixture of polyvinyl alcohol (PVA), Lac, PEO-PPO-PEO (F108) and gold nanoparticles (Au NPs), where F108 was used as an enzyme stabilizing additive and Au NPs was used to enhance the conductivity of the biosensor. Laser confocal scanning microscopy and electrochemical impedance spectroscopy proved that the enzyme was successfully encapsulated into the electrospun nanofibers. Under the optimal conditions, the lowest detection limit was found to be 0.04 μM (S/N = 3) for 2,4-DCP and the highest detection limit was found to be 12.10 μM for 4-CP. The sensitivity of the biosensor obtained in the linear range for chlorophenols followed the sequence 2,4-dichlorophenol (2,4-DCP) > 2,4,6-trichlorophenol (2,4,6-TCP) > 4-chlorophenol (4-CP). The sensing performance for chlorophenols was attributed to the suitable electrochemical interface of PVA/F108/Au NPs/Lac, resulting from biocompatibility, a high surface area-to-volume ratio (10.42 m(2) g(-1)) and superior mechanical properties of the electrospun nanofibers. The biosensor exhibited good repeatabilities of 7.6%, 2.8% and 9.0% (R.S.D.) and reproducibilities of 14.9%, 10.4% and 13.7% (R.S.D.) for 4-CP, 2,4-DCP and 2,4,6-TCP, respectively. Lac retained 65.8% of its initial activity after a 30-day storage period.