Indirect Determination of CTMAB with Sodium Chloride and Ammonium Thiocyanate by Floatation and Separation of Zinc

Cetyl-trimethylammoniumbromide(CTMAB)isaveryusefulcationicsurfactant,sothestudyondeterminationofCTMABassumesgreatimportance.AsmallamountofCTMABisgenerallydeterminedbyspectrophotometrybasingCTMABcombineswithtriazidetoformcoloredbinaryion-associationcomplex1-3.However,thosemethodsofdeterminationofCTMABhavedisadvantagesofsmalllinearrange,needofspecialreagent,determinationinbaseenvironment,etc.Inthispaper,indirectdeterminationofCTMABwithNaClandNH4SCNbyfloatationandseparationofZn(II…     

Effect of Supercritical Fluids on the Biological Activity of Absidia coerulea for the Hydroxylation of Reichsterin’s Substance Acetate

In a number of fermentation processes, organic solvents are often used due to the poorsolubility of many substrates and/or products in water. However, the interface betweenwater and organic phases may lead to the diffusion-limited bioconversion. Supercriticalfluid technology can be employed to eliminate the mass transfer resistance existed in thebiphasic system1-6. Hydrocortisone is an effective anti-inflammatory drug and an important precursor ofother steroid drugs. The C11β-hydroxylati…     

POLYMER-SUPPORTED SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS AS CATALYSTS FOR PHASE-TRANSFER REACTIONS

1. INTRODUCTION A variety of organic reactions have recently been reported to be catalysed by quaternary ammonium and phosphonium salts [1~4]. In same time, the attachment of phase-transfer catalysts to insoluble polymer supports greatly simplified their use in organic reactions [5~7]. The aim of this study was to investigate the effects of single and mixed ammonium and phosphonium salts, grafted on a 揼el-type?styrene-7% divinylbenzene copolymer, upon the phase-transfer catalytic process…     

PREPARATION OF POLYSULFONAMIDE/TiO_2 NANOCOMPOSITES BY SOL-GEL

1. INTRODUCTIONPolysulfonamide resin can be used to prepare heat-resistant fibers. The first investigation was started by the Chinese scientists in the 1970’s [1], then it is widely used in industry field. Its aerospace and fire protection application ha…     

注浆锚杆中扭转导波的传播特性

理论研究了扭转导波在注浆锚杆中的传播特性。首先建立了注浆锚杆两层复合结构中的扭转导波的频散方程,之后数值计算得到了扭转导波的能量速度、衰减频散曲线及导波在注浆锚杆中的位移分布情况。结果表明,(1)500kHz范围内,注浆锚杆中具有三种扭转导波模态T(0,1)~T(0,3),三种模态均具有频散性。随着频率逐渐增大,导波的能量速度逐渐增大,而衰减值逐渐减小。(2)50kHz和200kHz的T(0,1)模态扭转导波在锚杆体内的周向位移值较大,所以对锚杆体表面的轴向缺陷敏感,而导波在锚杆与注浆体接触面上的周向位移较大,从锚杆泄漏至注浆体中的能量较大,导波衰减较严重。(3)频率高于100kHz,锚杆直径的变化对T(0,1)模态的能量速度几乎无影响,而频率低于100kHz,注浆体弹性模量越大,T(0,1)模态的能量速度越小。     

一步水热法合成六方片状氢氧化镁及其生长习性分析的研究

以硝酸镁为原料,氨气为沉淀剂,采用一步水热法制备六方片状氢氧化镁,利用扫描电镜(SEM)和X射线衍射(XRD)对产品进行表征,结果表明120℃为较佳温度.采用Morphology程序对氢氧化镁生长习性进行理论分析,计算了其主要显露面族的表面能、表面附着能和晶面面积百分比等相关参数.计算结果表明,氢氧化镁(001)面会成为主要显露晶面,(101)面会成为经常显露晶面,其形貌大部分会呈现正六方片状但其中会掺杂着不规则的六边形片状结构与实验结果吻合.由温度引起的(001)晶面显露程度变化是导致宏观形貌非理想性的重要原因.本文结果为进一步与非理想形貌机理研究奠定了良好的基础.     

Using Raman Spectroscopy for Determination Methanol Quantity in Illegal Alcoholic Beverages

Illegal production of alcoholic beverages is a common problem in most countries.The consumption of these counterfeit alcoholic products in Turkey has increasingly been one of the major health concerns.In this study,a comparison between GC-MS and Raman spectroscopy techniques was made to determine the amount of methanol in BogmaRaki which is a counterfeit alcoholic beverage produced and consumed in Hatay region. Different ratios of methanol/ethanol concentrations were prepared to obtain a calibration curve.This curve was used to measure the amount of methanol in the actual product samples using both GC-MS and Raman spectros-copy techniques.Results obtained from both techniques were compared using Paired sample t-tests.The Limit of Detection and the Limit of Quantification values were determined as 0.03 (%v/v)and 0.11 (%v/v),re-spectively.Both techniques demonstrated a similar sensitivity in the determination of methanol concentration in these counterfeit products (p>0.05).Raman Spectroscopy,however,has an advantage of being easy to use, inexpensive,rapid and non-destructive analytical technique with little or no sample preparation.     

介孔球形LiFePO4/C原位复合材料制备与表征

磷酸铁锂由于其安全性好,价格低廉,理论比容量高等优势而成为一种重要的锂离子电池正极材料.本文利用微生物法与水热法相结合的新方法成功制备出介孔LiFePO4/C原位复合材料.以微生物为模板和碳源,通过与金属离子和磷酸根离子的矿化作用形成盐类混合物,经200℃水热反应,从而形成LiFePO4/C原位复合材料.通过结构与性能表征,该复合材料具有介孔球形结构,在0.1C倍率下的首次放电容量可达到134 mA·h.g-1,比普通水热法合成的样品的比容量提高了近30;,且其充放电性能有着很好的对称性和较小的极化现象.其性能显著提高的主要原因是材料具有介孔球形结构和原位复合碳的存在,从而促进了锂离子的嵌入与脱出和电子传导.     

低应力铌酸锂电光调Q开关的研究

本文分析了铌酸锂晶体应力,按照来源包括热应力、缺陷应力、加工应力和晶体受到的外力等.对铌酸锂晶体热处理时固溶体脱溶问题的初步分析,采用合适的工艺对晶体毛坯进行了去应力热处理;在调Q开关制作时开发了弹性装配技术取代传统的硬性夹持方案,消除了夹持应力对电光调Q开关的影响.制备的铌酸锂电光调Q开关得到了实际应用,有效提高了激光器工作的温度稳定性.     

压力对金属铌中氦原子凝聚的影响

 采用零温条件下的赝势-平面波方法和有限温度下的Car-Parrinello分子动力学方法,模拟了不同压力环境下氦原子在金属铌中的行为特征,研究了宿主缺陷和氦泡的形成机制。结果表明,闭电子壳层的氦原子在金属铌中具有刚球模型特征,其占据区域为金属自由电子的禁区,从而破坏铌原子之间的金属性键合。在常温条件下,局域高浓度的氦原子优先凝聚于近邻宿主空位缺陷处,从而形成氦泡;完整晶格中高浓度的氦将促使铌原子易位,形成间隙-空位模式的宿主缺陷,氦原子聚集于空位区域。完整宿主在压力（40 GPa）的作用下,晶格参数减小,铌原子之间的相互作用增强,尽管氦原子的存在削弱了铌原子之间的相互作用,位于格点上的铌原子仍难以借助热振动偏离格点形成空位,因而未能形成间隙-空位对和氦泡。