Spectrophotometric and gravimetric determination of sulfur in sebacate-base lubricants

Sulfur is determined in sebacate-base lubricants spectrophotometrically and gravimetrically. In the spectrophotometric method, a 0.2–0.3-g sample is treated with mixed acids, magnesium chloride is added, and the solution is evaporated to dryness. The sulfate is reduced to hydrogen sulfide by treatment with a mixture of hydriodic. hypophosphorous, and hydrochloric acids, and the hydrogen sulfide is distilled into ammonia solution. Lead citrate reagent is added and the brownish yellow color of lead sulfide sol is measured. An improved technique and apparatus for the distillation is described. In the gravimetric method, a 5-g sample is treated with mixed acids, antimony and tin are volatilized by treatment with hydrobromic acid, and sulfur is precipitated as barium sulfate. The recommended range of the spectrophotometric method is 0.005–0.15%,and that of the gravimetric method is 0.01–1% sulfur.     

用计算全息法检测卡塞格林系统主镜

为实现对卡塞格林光学系统中的非球面主镜表面面形的高精度检测,设计了一种二元位相型计算全息图(CGH)。介绍了工作原理,对CGH的相位模型参数的优化设计、衍射次级分离以及台阶位置与深度计算等关键问题进行了讨论。通过引入虚拟玻璃的概念快速建立非球面检测模型,针对卡塞格林系统主镜中心开孔的特点,通过加入同轴载波实现了衍射次级的完全分离,相比目前常用的倾斜载波方法简化了相位量化复杂度,数值仿真计算出了最优的台阶深度,降低了加工难度。给出了相应的设计方法及实例,研制投产了CGH。测试得到主镜面形的均方根误差为0.018λ,并与传统补偿器结果(RMS=0.019λ)进行对比,两者测试结果吻合,验证了该设计与检测方法的正确性,该设计方法简单快捷,适用于卡塞格林光学系统主镜面形检测。     

聚苯胺薄膜电极上示差脉冲伏安法可逆波理论研究

本文提出了聚苯胺(PANI)薄膜电极上示差脉冲伏安法可逆波理论,经验证理论和实验结果相符合.     

Behavior of Lβ2 visible satellites in gold around L1 threshold

The Au $L{\beta }_2$ visible satellites, $L{\beta }_2^{\prime }$ and $L{\beta }_2^{″}$ were measured around the $L_1$ absorption edge using a high-resolution Johann-type spectrometer at BL15XU, SPring-8. The relative intensities of the $L{\beta }_2^{\prime }$ and $L{\beta }_2^{″}$ satellites to that of the $L{\beta }_2$ line exhibit an abrupt jump at the $L_1$ threshold. The results suggest that the origin of the $L{\beta }_2$ satellites is mainly the $L_1$–$L_3{M}_{4,5}$ Coster–Kronig transitions.     

D241树脂分离纯化黄芩总黄酮的研究

本文研究了用241树脂分离纯化黄芩总黄酮的方法和工艺。实验结果表明：D241树脂对黄芩总黄酮的静态交换容量是77mg/ml树脂。在pH11.0、流速2.0BV/h、提取液中总黄酮浓度17.5mg/ml条件下，D241树脂对黄芩总黄酮的动态交换容量为43.8mg/ml。用60％甲醇作为黄芩总黄酮洗脱剂，在PH4.0、洗脱流速1.5BV/h条件下，4．5BV洗脱剂即可完全洗脱被D241树脂交换的黄芩总黄酮。与酸沉淀法相比较，经过除去果胶，总黄酮纯度由33．34％提高到74．9％，粗品收得率由11.52%降低至4.83%；经过D241树脂分离纯化，其纯度达到91.5%，产品收得率3.54%。     

A rapid solvent extraction method for the determination of caesium-137 in environmental materials

A solvent extraction method for the quantitative determination of caesium-137 in environmental samples is described. Caesium carrier is added to the ashed sample, which is dissolved with hydrochloric acid. The solution is filtered to remove any carbon and the pH is adjusted to 2.0. Sodium dodecylbenzene sulphonate is added and the extraction is done with phenol-nitrobenzene mixture. The organic phase is washed with EDTA solution and the caesium is stripped from the washed solvent with 6 M hydrochloric acid. The caesium is precipitated as caesium chlorostannate to ensure absolute decontamination from potassium-40. Recovery from standard solution is about 85% and from vegetation, rainwater and effluent samples about 80%. The method is applicable in the presence of large quantities of interfering ions, and decontamination factors for many nuclides are greater than 10³.     

N,O-羧甲基壳聚糖的合成和性质研究

采用多段升温法将壳聚糖改性,合成了取代度为1.84、平均分子量为3.08×105、等电点为7.28的N,O-羧甲基壳聚糖(CMC),分别用紫外光谱、红外光谱、荧光光谱对其结构进行了表征,并对其水溶液的Zeta电位、电导率、表面张力以及水分散体系中羧甲基壳聚糖微粒的粒径分布进行了研究.结果表明, N,O-羧甲基壳聚糖具有表面活性;介质的pH值和浓度对羧甲基壳聚糖溶液的稳定性有很大的影响.     

Über die anodische oxidation von hydrazinderivaten an platin im sauren elektrolyten: Teil III. Dimethylhydrazin

As can be seen from controlled potential electrolysis the anodic oxidation of dimethyl-hydrazine in acid solutions yields two electrons per DMH molecule, giving the following overall reaction:

${(C{H}_3)}_2\stackrel{+}{N}HN{H}_2\to {(C{H}_3)}_2\stackrel{+}{N}=NH+2H^{+}+2e^{?}$

But the kinetics of the reaction is determined by a 1-electron step as the 110 mV Tafel slope shows. The reaction orders for DMH and H⁺ are z_DMH=0.54 and z_H⁺=?0.55 respectively. These results can be interpreted by the following reaction mechanism, where adsorption and desorption step are governed by the Temkin isotherm

$\begin{array}{l}{\left(C{H}_3\right)}_2\stackrel{+}{N}HN{H}_2?{\left(C{H}_3\right)}_2\stackrel{+}{N}HNH?Pt+H^{+}+e^{?}\\ {\left(C{H}_3\right)}_2\stackrel{+}{N}HNH?Pt\stackrel{r.d.s.}{\to }{\left(C{H}_3\right)}_2\stackrel{+}{N}=NH+PtH\\ PtH\to Pt+H^{+}+e^{?}\end{array}$

     

On energy bounds derived from the conjugate eigenvalue problem

An upper bound for E₀, which has been derived from the conjugate eigenvalue problem by Hall, is discussed. It is emphasized that the bound is only guaranteed when V is negative-definite. An alternative bound is presented which is free from this restriction, and the underlying iterative procedure is given. Hall's result is generalized to admit internuclear distances, and the theory is illustrated by a one-dimensional system with delta-function potentials. Some disadvantages of the approach are mentioned.     

Development and validation of a gas chromatography/mass spectrometry procedure for confirmation of para-toluenesulfonamide in edible fish fillet tissue

Chloramine-T is a disinfectant being developed as a treatment for bacterial gill disease in cultured fish. As part of the drug approval process, a method is required for the confirmation of chloramine-T residues in edible fish tissue. The marker residue that will be used to determine the depletion of chloramine-T residues from the edible tissue of treated fish is para-toluenesulfonamide (p-TSA), a metabolite of chloramine-T. The development and validation of a procedure for the confirmation of p-TSA is described. Homogenized fish tissue is dried by mixing with anhydrous sodium sulfate, and the mixture is extracted with methylene chloride. The extract is passed through a silica gel solid-phase extraction column, from which p-TSA is subsequently eluted with acetonitrile. The acetonitrile extract is evaporated, and the oily residue is dissolved in hexane. The hexane solution is shaken with fresh acetonitrile. The acetonitrile solution is evaporated and the residue is redissolved in dilute potassium hydroxide solution. The aqueous solution is extracted with methylene chloride to further remove more of the fat co-extractive. The aqueous solution is reacted with pentafluorobenzyl bromide in presence of tetrabutylammonium hydrogensulfate. The resulting di-(pentafluorobenzyl) derivative of p-TSA is analyzed by gas chromatography/mass spectrometry. This method permits the confirmation of p-TSA in edible fish tissue at 20 ppb.     

水性聚氨酯的制备及其性能的研究

本文以琥珀酸酐与三羟甲基丙烷反应,制得了含有羟基和羧基的酯类亲水性单体,并以此单体与ＴＤＩ和ＰＰＧ－１０００反应,制得了含有羧基的聚氨酯预聚体,在三乙醇胺水溶液中分散得到了水性聚氨酯（简称ＷＰＵ）。本文对预聚体的溶剂种类和用量,对乳胶粒的大小及形状的影响进行了研究,确认溶剂的用量越大,乳胶的粒径就越小;以丙酮作溶剂,乳胶粒为棒状或橄榄球状,而以丁酮为溶剂,得到的乳胶粒为圆球状。通过改变亲水单体的用     

氟吗啉合成工艺热危险性及动力学研究

氟吗啉是一种新型杀菌剂, 合成工艺热危险性和动力学研究将解决工程问题, 并保障安全生产. 采用差示扫描量热-热重分析仪(DSC-TG)测试主要原料、中间体和产品的热稳定性, 采用反应量热仪(RC1)研究反应热行为, 同时开展反应动力学研究. 研究结果显示, 主要中间体(3,4-二甲氧基苯基)(4-氟苯基)甲酮吸热分解温度为559.3 K, 乙酰吗啉吸热分解温度为478.2 K, 氟吗啉吸热分解温度为638.6 K. 氟吗啉合成反应摩尔放热量为15.44 kJ/mol, 绝热温升ΔT_ad为9.1 K, 本研究合成工艺的热危险性较小. 氟吗啉合成反应动力学方程为：r_A=kc_A^a=8.34×10^-3C_A^0.57, 对主要中间体(3,4-二甲氧基苯基)(4-氟苯基)甲酮的反应级数为0.57 级.     

Determination of free, total, and esterified cholesterol by high-performance liquid chromatography

A method is described for measuring free, total, and esterified cholesterol in blood serum in which reversed-phase liquid chromatography is used and the eluate is monitored at 200 nm. The sample for total cholesterol is prepared according to the Abell-Kendall procedure, and for free cholesterol an extract of serum--isopropanol (1:5, v/v) is used. The column is a muBondapak C18, 10 micrometers, and the mobile phase for total cholesterol is isopropanol--acetonitrile (50:50, v/v); for free cholesterol, it is isopropanol--acetonitrile--water (60:30:10). An approximation of the free cholesterol, triglycerides, and individual cholesteryl esters is obtained from single chromatograms of isopropanol extracts of serum if the first mobile phase is used. In a comparison study with the Abell-Kendall method for total cholesterol, the correlation is excellent and the precision is acceptable.     

Infrared determination of traces of sulfate in reagent chemicals

A method for determining traces of sulfate in reagent-grade chemicals is presented. The sample is passed through an alumina column in acid solution to isolate the sulfate, which is then eluted with ammonia. Potassium bromide is added to an aliquot of the eluate, and the solution is freeze-dried. The resulting powder is pressed into a disk whose infrared spectrum is recorded. The method is reasonably accurate and requires a minimum of operator time per sample because a large number of samples can be processed together