电化学技术制备纳米材料研究的新进展

利用电化学方法制备与组装纳米材料是近年来发展起来的一项新技术.本文对电化学方法在纳米材料制备中的应用及其研究进展做了较为全面的概述,着重介绍了模板电化学法合成纳米材料、稳定剂保护下电化学还原法制备金属溶胶、电化学台阶边缘修饰法制备一维纳米材料以及脉冲超声电化学法制备纳米粒子,并对其应用前景做了展望.     

稀土氟化物微纳米材料制备方法的研究进展

稀土氟化物纳米材料由于其特殊的光、电、磁性质,在光学器件、显示、生物标记、光学晶体等领域有着广泛的应用,已成为材料科学领域的研究热点之一。目前研究者已用沉淀法、微乳液法、水热与溶剂热法、溶胶-凝胶法、微波法、超声波法、前驱体热解法、静电纺丝法等成功地制备出了纳米颗粒、纳米线、纳米膜、多面体纳米晶、复合结构纳米晶、核壳结构纳米材料等稀土氟化物纳米材料。本文总结了上述几种制备方法的研究进展,讨论了其优缺点,并结合课题组在稀土氟化物纳米材料制备方面的工作,对纳米稀土氟化物制备方法的发展方向做了展望。     

一维硅纳米材料的可控制备和机理

一维硅纳米材料具有不同于体硅材料的特殊光电性能,在光电子领域具有潜在的应用价值.通过"剪裁"一维硅纳米材料的尺寸、形貌和化学组分等,可以调控其物理化学性质.因此,探索并实现一维硅纳米材料的可控制备对于其实际应用至关重要.本文综述了一维硅纳米材料可控制备的最新进展,介绍了几种重要的制备方法及其生长机理,比较了不同方法在可控制备一维硅纳米材料中的优缺点,并展望了其未来发展方向.     

超临界流体技术制备纳米材料的研究与展望

纳米科技是人们普遍关注的重要领域，而纳米材料充当其中的基础性角色。本文介绍了在新兴绿色环保介质——超临界流体中纳米材料的合成及其制备，涉及范围包括从准零纳米微粒到三维纳米材料，从无机纳米材料到有机聚合物纳米材料。其中不仅介绍了超临界流体中纳米材料的制备方法，同时也包括制备过程中超临界流体特殊性质，如溶胀、塑化和地表面张力所起的重要作用，并对超临界流体技术在纳米材料制备中的应用前景进行展望。     

聚合物负载纳米材料及其在催化领域的应用

纳米材料几何尺寸小、比表面积大,具有广阔的应用前景。以聚合物负载纳米材料能抑制其聚集、提高稳定性,更好地实现其功能。本文总结了聚合物负载纳米材料的制备方法,探讨了这些复合材料在催化领域中的应用,并对其发展趋势作了总结和展望。     

模板及其在纳米材料合成领域的应用

模板法是合成纳米材料的重要方法之一.本文综述了模板的分类、制备方法、性能以及在纳米材料合成领域中的应用,并对模板合成的未来发展进行了展望。     

磁性纳米材料在样品前处理中的应用进展

磁性纳米材料作为一种新型功能复合材料,因其具有吸附能力强、表面可修饰、易分离和良好的生物相容性等特点,已广泛应用于生物传感器、药物传导和医学成像方面。由于磁性纳米材料分离速度快且吸附性能好,因此在分析化学样品前处理中的应用也日益受到人们的关注。本文简略介绍了磁性纳米材料的特性、分类及制备方法,综述了磁性纳米材料在分离和富集生物大分子、有机物和无机物中的应用,并展望了磁性纳米材料的应用前景。     

磁性纳米材料在样品前处理中的应用进展与展望

在样品前处理技术中,吸附剂材料起关键作用。随着纳米材料的发展,越来越多的纳米材料被用作吸附剂以提高对目标物的萃取效率。磁性纳米材料因其具有易于分离、表面可修饰、吸附能力强和良好的生物相容性等优异性能,已广泛应用于分析方法的样品前处理技术中。该文通过对磁性纳米材料在磁性固相萃取和在其他样品前处理技术中的研究与应用展开总结和论述,对磁性纳米材料的稳定性、作用力、比表面积及孔径调控的制备进行了阐述,展望了磁性纳米材料在分离科学中的应用前景,为进一步研究磁性纳米材料的应用提供了参考。     

二维硫化钼的溶液法制备及其复合材料在光、电催化领域的应用

作为二维(2D)过渡金属硫族化合物(TMDs)的成员之一,MoS_2因其独特的物理化学性质及在自然界中丰富的含量成为目前研究最广泛的一种半导体。凭借超薄的层状结构和可调控的禁带宽度,单层和多层的二维MoS_2纳米材料在众多研究领域都备受关注。基于溶液法的合成工艺(如超声辅助液相剥离和湿化学合成法)有望实现大规模、高产量地制备二维MoS_2纳米材料,更重要的是,基于溶液法合成的二维MoS_2纳米材料便于作为模板或者载体来制备功能性复合纳米材料,有利于进一步提升其在相关应用中的性能。本文重点介绍了基于溶液制备二维MoS_2纳米材料的各种合成方法,同时特别关注了溶液法制备的二维MoS_2复合纳米材料及其在光、电催化方面的应用,并展望了溶液法合成二维MoS_2及其复合材料的应用前景和挑战。     

模板法制备无机纳米材料的研究进展

模板法在无机纳米材料的制备过程中能够有效地控制形貌、粒径和结构,已成为合成无机纳米材料的前沿方法。综述了模板法制备无机纳米材料的研究进展,主要介绍了硬模板剂(多孔阳极氧化铝、介孔碳)和软模板剂(高分子聚合物、生物高分子)的制备及其应用,结合模板法的作用机制,重点论述了不同种类的模板剂在无机纳米材料制备过程中对于形貌的影响。并对模板法制备无机纳米材料的前景和现存问题进行了总结。参考文献35篇。     

超声波辐射固-液相芳氧(硫)基羧酸的合成

芳氧(硫)基羧酸广泛应用于农业等方面。近年来有关芳氧基乙酸合成的报道,如:液-液两相催化,固-液两相催化,三相催化等,这些方法反应条件温和,产率较高,但需要昂贵的相转移催化剂,后处理麻烦。本文报道利用超声波辐射固-液相合成芳氧(硫)基羧酸得到的一些结果。     

联苯双酯的荧光性质及其分析应用

研究联苯双酯的荧光性质,并建立用荧光光度法测定联苯双酯滴丸中联苯双酯含量的方法.样品用乙醇超声提取,过滤,取续滤液,在室温下用乙醇作溶剂直接测定荧光强度计算联苯双酯的含量,并用RP-HPLC测定的结果作对照.实验表明,联苯双酯有较强的荧光特性,最大激发波长和发射波长分别在282 nm和388 nm;质量浓度在0.24～3.4 mg/L范围内,荧光强度与浓度有良好的线性关系,检出限为(3σ/k) 0.010 mg/L,对2.4 mg/L的联苯双酯测定的相对标准偏差为1.1% (n=10).方法用于联苯双酯滴丸中联苯双酯含量的测定,相对标准偏差RSD (n=5)在0.83%～2.8%,与RP-HPLC测定结果相比,无论是精密度还是准确度不存在显著差异.方法已用于联苯双酯滴丸中联苯双酯含量的测定.     

Biodegradable poly(l-lactic acid) nanofiber prepared by a carbon dioxide laser supersonic drawing

Biodegradable poly(l-lactic acid) (PLLA) nanofiber was prepared by a carbon dioxide (CO₂) laser supersonic drawing which was carried out by irradiating the laser on an as-spun fiber in a supersonic jet. The supersonic jet was generated by blowing off air into a vacuum chamber from a fiber supplying orifice. The flow velocity from the orifice can be estimated by applying Graham’s theorem from the pressure difference between the atmospheric pressure and the pressure of the vacuum chamber. The fastest flow velocity estimated was 396 m s⁻¹ when the chamber pressure was 6 kPa. The PLLA nanofiber having an average diameter of 0.132 μm was obtained when the supersonic drawing was carried out by irradiating the laser at 177 W cm⁻² on the as-spun fiber supplied at 0.1 m min⁻¹ in the vacuum chamber at 6 kPa. The obtained nanofiber had a draw ratio of about 323,000 and a degree of crystallinity of 45%, and its diameter uniformity was high. The CO₂ laser supersonic drawing was a new route for preparation of various nanofibers without using any solvent.     

Measurements of Temperature and Electron Number Density in a dc Argon–Nitrogen Plasma Torch—Supersonic Operation

The diagnostics study on supersonic argon/nitrogen plasma jets expanded into a low-pressure test chamber is carried out by means of emission spectroscopy and enthalpy probe measurement techniques. The spatial distributions of electron density, temperatures, and associated shock structure effects in plasma jets are investigated in conjunction with their direct dependency upon the chamber pressure. The experimental results show the occurrence and the position of different zones; i.e., supersonic expansion, stationary shock waves and subsonic jet at pressures below 51 kPa. Flow fluctuations due to the oblique shock wave at 39 kPa background pressure are observed and discussed. The electron density profiles show variations along the plasma axis that coincide with the position of the shock waves. The experimental results show the transition from the moderately under-expanded to the strongly under-expanded jet structure induced by lowering of the chamber pressure.     

单离子检测法测定祛斑类化妆品中氢醌和苯酚

应用气质联用单离子检测法（SIM）测定祛斑类化妆品中氢醌和苯酚。以乙醇为溶剂，超声波快速提取，分别以m/z 110和m/z94为检测离子，总离子流图定性，SIM图定量，方法简便、快速、灵敏，对氢醌和苯酚的检出限分别为0.1ng、0.05ng，回收率分别为91.5%-102%、86.5%-98.7%，相对标准偏差分别为1.41%、0.41％。     

The rotational spectrum and structure of HOOOH

Dihydrogen trioxide, HOOOH, which is a species with fundamental importance for understanding the chain formation ability of the oxygen atom, was detected in a supersonic jet by a Fourier transform microwave spectrometer with a pulsed discharge nozzle, together with double resonance and triple resonance techniques. Its precise molecular structure was determined from the experimentally determined rotational constants of HOOOH and its isotopomer, DOOOD. Many of the microwave and millimeter wave transitions can now be accurately predicted, which could be facilitated for remote sensing of the molecule to elucidate its roles in various chemical processes.     

聚合所得初生聚乙烯的晶型

聚合所得初生聚乙烯的晶型伍青，张启兴，卢泽俭，王海华，欧阳巍，林尚安，张光华（中山大学高分子研究所，广州，５１０２７５）（中国科学院广州化学研究所）关键词聚乙烯，结晶，单斜晶，颗粒形态热力学稳定的聚乙烯晶型为正交晶系［１］．当聚乙烯受一定应力作用时如...     

Vibrational excitation and relaxation of five polyatomic molecules in an electrical discharge

Vibrational excitation and relaxation of five linear polyatomic molecules, OCS, OC3S, HC3N, HC5N, and SiC2S, have been studied by Fourier transform microwave spectroscopy in a supersonic expansion after the application of a low-current dc electric discharge. For each chain, the populations in bending and stretching modes have been characterized as a function of the applied discharge current; for stable OCS and HC3N, vibrational populations were studied as well in the absence of a discharge. With no discharge present the derived vibrational temperatures are slightly below T, the temperature of the gas before the supersonic expansion (i.e., 300 K). In the presence of the discharge, vibrational excitation occurs via inelastic collisions with the electrons and the vibrational temperatures rise as the applied current increases. Global vibrational relaxation is governed by rapid vibration-vibration (VV) energy transfer and slow vibration-translation (VT) energy transfer. The latter process is rate-determining and depends primarily on the wave number of the vibration. Vibrational modes with wave numbers near and below kT/hc (where T = 300 K and kT/hc-210 cm(-1)) are efficiently cooled by VT transfer because a sufficient number of collisions occur in the initial stages of the supersonic expansion. Vibrational modes with wave numbers around 450 cm(-l) appear to be inefficiently cooled in the molecular beam; at these energies VV and VT rates are probably comparable. For high-frequency vibrations, VV energy transfer dominates. For the longer chains OC3S and HC5N, higher-lying modes are generally not detectable and vibrational temperatures of most lower-lying modes were found to be lower than those of OCS and HC3N, suggesting that as the size of the molecules increases, intermode VV transfer becomes more efficient, plausibly due to the higher density of vibrational levels. New high resolution spectroscopic data have been obtained for several vibrationally excited states of OC3S, HC3N, and HC5N. Rotational lines of the 13C and 15N isotopic species of HC5N have been measured, yielding improved rotational and centrifugal distortion constants; 14N nitrogen quadrupole coupling constants for the isotopic species of HC5N with 13C have been determined for the first time.     

Modeling and computational simulation for supersonic flutter prediction of polymer/GNP/fiber laminated composite joined conical-conical shells

This paper is presented to study the supersonic flutter characteristics of laminated joined conical-conical shells made of epoxy as the matrix and fibers and graphene nanoplatelets (GNPs) as the reinforcements. The mathematical modeling of the shell and the aerodynamic pressure are performed sequentially using the first-order shear deformation theory (FSDT) and the supersonic piston theory incorporating the aerodynamic damping coefficient. The effective elasticity and shear modulus, Poisson’s ratios, and density are estimated using the rule of mixture, Halpin-Tsai model, and micromechanical relations. The governing equations and associated boundary and compatibility conditions are derived utilizing Hamilton’s principle and are solved in the circumferential direction and numerically in the meridional direction via the differential quadrature method (DQM). The natural frequencies and mode shapes are obtained, and the influences of various parameters on the flutter boundaries are examined including the geometrical characteristics of the shell segments, boundary conditions, circumferential wave number, and weight fractions of the GNPs and fibers. It is concluded that by increasing the weight fractions of the fibers and the GNPs, the natural frequencies grow and the aeroelastic stability improves.     

反相高效液相色谱法测定肾舒冲剂水煎液中的小檗碱

 :应用反相高效液相色谱法检测了肾舒冲剂水煎液中的小檗碱。样品经超声提取后,以C18化学键合硅胶为固定相,乙腈-0.04mol/LH3PO4(体积比为42∶58)为流动相,用349nm的波长定量检测。测定结果表明,小檗碱的质量浓度在1.2～19.2mg/L范围内线性良好,最低检测限为0.6mg/L,测定批内(n=5)及批间(n=5)相对标准偏差分别为0.6%～3.5%和5.3%～6.5%,回收率为89.10%～91.35%。