Ce,Mn∶YAG单晶的生长及光学性能

采用提拉法生长了白光发光二极管(LED)用Ce,Mn∶YAG单晶,通过X射线衍射(XRD)测试、X射线吸收精细结构(XAFS)测试、吸收光谱和激发发射光谱对其晶相结构、掺杂Mn的价态和光谱特性进行了表征,并研究了晶片厚度及驱动电流的变化对LED器件光电性能的影响.在460 nm蓝光的激发下,Ce,Mn∶YAG单晶的发射光谱可由中心波长526和566 nm的宽带发射峰复合而成.XAFS测试结果表明,所得单晶中掺杂Mn的价态以正二价为主.由于Ce3+和Mn2+在YAG单晶中存在能量传递,荧光光谱中566 nm处的橙色发射峰对应于Mn2+离子4T1→6A1能级的辐射跃迁.     

含硫化合物的SK~αX射线荧光光谱的研究

在RIGAKU 3070X射线光谱仪(双晶)上系统测定了含硫化合物的SK~α谱; 用统计试验最优化方法处理实验数据, 得到了峰谱的峰位, 非对称因子, 半高宽度等信息; 并计算了化学位移和部分化合物硫原子的净电荷。讨论了硫化合物SK~α谱化学位移的变化规律及原因。线性回归分析结果表明: 硫化物SK~α谱的化学位移与价态, 硫的含氧化合物SK~α谱的化学位移与O/S原子数比之间都有较好的线性关系; 并给出了线性相关系数及线性方程。     

预焙阳极微量元素XRF测定方法的研究

使用X射线荧光光谱法测定预焙阳极中的微量和痕量元素,以粉末压片法制样,选用瑞士R＆D碳素公司的C-300系列标准样品,并用仪器软件Super Q中提供的飞利浦模式的经验系数（Classic）和铑（Rh）靶康普顿散射线内标法校正元素间的谱线重叠干扰和基体效应,通过充分研磨样品消除颗粒效应,使用Magix（PW2403）X射线荧光光谱仪对样品中的F、Na、Mg、Al、Si、P、S、C1、K、Ca、Ba、Ti、V、Cr、Mn、Fe、Ni、Cu、Zn、Ph、Sr和Sn共22个元素进行测定,11次测定的相对标准偏差小于10％,多数元素的检出限小于1μg·g^-1。用R＆D标准样品的混合样验证,测量结果与标准值的误差在化学分析允许范围内。     

X射线荧光光谱法测定哈氏C-276合金中10种元素

采用X射线荧光光谱法,可实现同时测定C-276合金中Si,Mn,P,Cr,Fe,Mo,W,V,Co,Cu,方法简便快速,便于生产过程控制和产品分析。采用成分相近的17种标准物质建立工作曲线,优化了测量条件并进行谱线重叠校正和元素间的吸收和增强效应的校正,各元素含量与测量强度均能呈现良好的线性关系。用于C-276合金中各元素的测定,具有良好的精密度,测定值与分光光度法、容量法、重量法等标准方法测定结果显示较好的一致性。为建立X射线荧光光谱法测定镍基合金成分提供了思路,为研究X射线荧光光谱分析镍基合金的干扰提供事实依据。     

基于蒙特卡洛方法的X射线探测器能谱响应研究

为解决X射线荧光测量过程中的仪器刻度和校正难题,通过理论研究并运用蒙特卡洛方法对X射线荧光仪进行建模,得到了X射线探测器能谱响曲线。结果表明:模拟的X射线探测器能谱响应全谱与实测情况基本一致,而主成份谱线则高度一致,特征峰半高宽相对误差均在5%以内。方法为X射线荧光测量的仪器刻度和校正提供重要的研究信息,不仅为元素分析工作节省大量人力物力,也为无标样X射线荧光分析提供了有力的理论支撑。方法也可用于X射线荧光分析过程中的其他研究领域。     

X射线荧光光谱法测定Zn镀层质量厚度及计算谱线选择问题研究

用X射线荧光光谱法测定了Fe基上Zn镀层的质量厚度；研究了厚度不同时选用不同谱线计算对测定结果的影响，发现在镀层质量厚度较小时（约〈14mg／cm^2）测量Zn元素的Kα线，质量厚度较大时选择Zn的Kα和Fe的Kα线共同计算，用纯元素和相似标样校正测定结果之间的偏差最小；用纯元素作校正标样测定了3个标准样品的Zn镀层质量厚度，计算结果与标准值符舍得较好。     

熔片X射线荧光光谱法测定锡矿石中八种重金属元素

建立了X射线荧光光谱法测定锡矿石中8种重金属元素Fe,Cu,Zn,As,Sn,Sb,Pb,Bi的分析方法。通过固体纯物质机械混合研磨配制了校准曲线所用的标准样品。采用混合熔剂(Li2B4O7:Li BO2:Li F=10:2.5:1,质量比)加氧化剂Li NO3熔融制备了X射线荧光法所用玻璃片样品(混合熔剂:Li NO3:试样=20:3:1质量比)。在高温熔融过程中,易挥发元素As,Pb一直存在于熔体中,未随熔融时间的增加而出现挥发损失。使用外加内标元素法(In和Co)对元素Sn,Sb,Fe的吸收增强效应进行校正,其它元素使用Compton散射线内标法进行校正。采用干扰曲线法校正Pb Lα对As Kα以及Sn Lβ1背景峰对Sb Lα的谱线重叠干扰。各元素检出限分别为Fe 0.0074%,Cu 0.0043%,Zn 0.0025%,As 0.0036%,Sn 0.019%,Sb 0.010%,Pb 0.0039%,Bi 0.0026%。对国家一级标准物质锡精矿GBW07232和锡矿石GBW07281分别进行10次制样测量,各元素精密度(RSD)在0.11%~18%之间。     

大洋多金属结核中27个元素的快速分析

利用飞利浦PW2400X射线荧光光谱仪测定了多金属结核中的Na2O、MgO、Al2O3、SiO2、P2O5、SO3、Cl、K2O、CaO、TiO2、V、Mn、Fe、Co、Ni、Cu、Zn、As、Rb、Sb、Y、Zr、Mo、Ba、La、Ce和Pb27种组分。采用粉末直接压片法制样,理论α系数（对分析线波长大于铁吸收限的元素）和以RhKβ１康普顿峰为背景的峰／背比法９对于其分析线波长小于铁吸收限的元素）校正元素间的吸收－增强效应,用国际锰结核标准样品建立校准方程（同时包括谱线重叠校正项）,方法经标准物质检验,具有较好准确度,能满足大洋多金属结构资源调查、评价要求。对主、次和绝大多数痕量组分,方法的相对标准偏差（ＲＳＤ,n=10）小于５％。与其他多元素分析方法相比,制样简单快速,而且是一种“环境友好”的“绿色”分析方法。     

SDD探测X射线中BP网络全谱定量分析技术研究

针对能量色散X荧光分析技术中面临的能谱复杂、标样难于制备、基体效应难于校正等问题,建立了基于BP神经网络的特征X射线全谱分析模型,对SDD探测器测量获得的Ti-V-Fe伪三元系样品特征X射线荧光谱进行定量分析,对含量较高的Fe元素的分析误差范围在0.06%～2.5%内,含量较低的Ti和V元素分析误差范围在0.33%～8.4%内,基本克服了由于谱峰重叠和基体效应对解谱带来的复杂性。     

不同工艺和原料对Mn_(1.2)Fe_(0.8)P_(0.48)Si_(0.52)化合物磁热效应的影响

用不同的工艺和原料制备了3个名义成分相同的Mn1.2Fe0.8P0.48S i0.52化合物。X射线衍射结果表明,3个化合物均为Fe2P型六角结构(空间群为P-62m),并且存在少量的(Fe,Mn)3S i相。通过磁性测量发现,3个样品的居里温度有所不同,但是都在室温附近(270~290 K)。以Fe2P为原料制备的化合物具有较大的磁熵变,在1.5 T的磁场变化下其最大磁熵变为13.6 J.(kg.K)-1。以行星样品球磨机制备的化合物具有较小的热滞,最小热滞为6.7 K。这些表明不同的制备工艺和原料对化合物的居里温度、热滞和磁熵变都具有一定的影响。同时低成本的原料、简单的制备工艺、较小的热滞和较大的磁熵变使得Mn1.2Fe0.8P0.48S i0.52化合物成为一种理想的室温磁致冷候选材料。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。