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.     

植物甾醇女士访谈录

通过采访植物甾醇女士,了解植物甾醇家族的成员、基本性质、生理功能等。揭示了其降低胆固醇、减肥、美容功能的基本原理,了解了抗癌机理,介绍了植物甾醇在食物中的分布、人体吸收困难的原因及对策,为人类健康生活提出膳食建议。     

Design of YCF-1 mobile γ irradiator

YCF-1 Mobile irradiator is designed by BINE of China. It has been put into running in YanJi city of Jilin province. It is able to be moved to border and distance places and area lumped and spreading out of agricultural products to service. It can play a important role in demonstration and extending irradiation technology in food irradiation, disinfestation, sterilization and quarantine, etc. This paper describes the features and design considerations of mobile irradiator.This irradiator adopted Cesium-137 source. The design capacity of loading source is 9.25PBq (250kCi), A half-time of Cs- 137 is 30.2 years long, exchanging source is not needed utilization rate of energy is higher, and the shielding is thinner, The Weight is lighter, The dose rate on the surface of it is 0.0025mSv/h in accordance with national standard. The internal size of irradiation room is 1800×1800×900mm (L×W×H), The sheilding of irradiation room is a steel shell filled with lead. The thickness of lead is 18cm. The irradiator is installed on a special flat truck. The size of the truck is 7000×3400×4200mm (L×W×H). The weight of irradiator is more than 80 150kw. The main components and parts of irradiator are: source, source racks and hoist, irradiation chamber, storage source chamber, the product's transport system, dose monitoring system, ventilation system and safety interlock system, etc.     

由乳酸合成乳酸乙酯反应动力学的研究

研究了用强酸性阳离子交换树脂催化乳酸和乙醇酯化反应的动力学,通过对实验结果的分析,发现该反应正反应为二级反应,逆反应为零级反应,并由此推导出了反应动力学方程。同时还发现在温度较低时这一反应存在诱导期现象,并对这一现象进行了分析。     

The Iodimetric Value Measurement of Expanded Graphite

The shape of expanded graphite is a netted and hollow structure.It is very easy to adsorb molecules and adsorption power is better. The research has proved:the expanded graphite had its ability to adsorb weigh oil etc. The capacity of adsorptive materials has been expressed by the iodimetric adsorption value, but the iodimetric adsorptive value of expanded graphite has not been reported until so far.The paper measures the iodimetric adsorption value by the iodimetry, and the apparatus is used easily and simply. The operation is not more difficult and the accuracy is higher, and the reagent is usual.     

诺氟沙星的交流示波极谱滴定法研究

本文报道了示波极谱滴定法测定诺氟沙星的含量。用ＰＨ４．４的ＨＡｃ－ＮａＡｃ缓冲溶液溶解药样，并与过量的四苯硼钠作用生成沉淀。过滤后，用硫酸亚铊回滴过量的Ｎａ－ＴＰＢ，由示波极谱图［ｄＥ／ｄｔ＝ｆ（Ｅ）］上ＴＰＢ切口的消失指示滴定络点，进而在该溶液中进行空白实验。     

N，N－二甲基甘氨酸乙酯分解反应机理的理论研究

利用量子化学计算方法MP2／6－31＋G^*研究了N，N－二甲基甘氨酸乙酯在气 相中热分解反应机理，并计算了反应的协同性，得出此反应是一个多步反应过程。 主要有两个阶段：第一个阶级是N，N－二甲基甘氨酸乙酯热分解产生N，－N二甲基 甘氨酸中间体和乙烯，第二个阶段是N，N－二甲基甘氨酸进一步分解生成三甲氨和 二氧化碳。第一个反应阶段为速率控制步骤。研究表明，该反应机理是一个非协同 的质子转移过程。计算结果与实验值吻合。     

添加改性松香对生漆漆膜性能的影响

通过添加松香、改性松香对生漆漆膜进行改性,研究结果表明,加入改性松香能改善生漆漆膜性能,在反应温度为80℃时,加入生漆质量5％的聚合松香效果最佳,附着力为1级,抗冲击力为35kg／cm,铅笔划痕为3H。反应温度对漆膜性能有很大影响,当加入生漆质量5％的聚合松香,反应温度从50℃升至80℃时,附着力从3级提高到1级,抗冲击力从10kg／cm提高到35kg／cm,铅笔划痕从H升至3H。红外光谱分析表明,天然松香对生漆性能的增强效果是由于与生漆发生了化学反应,而聚合松香对生漆性能的增强效果是协同作用造成的。     

Surface melting description

The surface melting is regarded in terms of the order parameter profiles which characterise phases extended inside a whole sample. The characterisation of the phase is, however, due to the order parameter behavior at the surface. The phase really observed is predicted by means of the thermodynamic conditions; thus, the surface melting phase is in competition to the softening modes at the surface. The presented idea is based on the discussion concerning the possible results of the leading theories, a modified van der Waals approach and an Ising type model for pseudospins. The experimental evidence is reviewed and interpreted.     

On the Interfacial Deformation of a Magnetic Liquid Drop under the Simultaneous Action of Electric and Magnetic Fields

The influence of uniform constant magnetic and electric fields, acting simultaneously, on a magnetic fluid drop is theoretically investigated. The drop is suspended in another magnetic fluid that is immiscible with the former. Both fluids are regarded as incompressible, viscous, weakly electrically conducting, polarizable, and magnetizable. The relative orientation of electric and magnetic intensity vectors is arbitrary. The equation for the surface of the drop is obtained in the approximation of small distortion of the drop. It is shown that the surface is an ellipsoid whose semiaxes can be expressed in terms of the intensity vectors of the electric and magnetic fields. The relations determining the orientation of its principal axes are also obtained. Copyright 2001 Academic Press.     

MoqRuyXz(X=S，Se，Te)纳米簇电催化还原氧的性能对比研究

直接甲醇燃料电池存有两个较为突出的技术问题,即:阳极催化剂活性低和甲醇渗透[1～4]。针对“甲醇渗透”(cross-over)问题有两种解决途径:一、使用低甲醇渗透率电解质膜(阻醇膜),二、使用抗甲醇氧还原电催化剂[4]。目前,多数改性或新型膜材料的阻醇率有一定提高,然而膜的电导率等指标不够理想[5～7]。抗甲醇氧还原催化材料的开发研究正逐渐受到重视[4]。因过渡金属纳米簇硫族化合物电催化剂的活性、抗甲醇性、稳定性高、成本低逐渐得到青睐,是有竞争力的Pt替代催化材料[7～15]。过渡金属纳米簇硫族化合物MqM′yXz的金属核M′多为Ru,掺杂…     

电感耦合等离子体质谱法测定氧化钕中砷含量

建立草酸沉淀分离氧化钕,用校正方程消除残余钕离子产生的双电荷离子干扰,电感耦合等离子体质谱法测定砷含量的方法。选择了溶解样品条件,硝酸溶解样品即能满足检测要求;优化了仪器条件,功率1500W,雾化器流量0.86L/min;进行了内标元素的选择,确定Rh为最佳校正内标元素;确定用草酸分离基体并结合干扰校正方程消除钕的双电荷离子干扰;方法检出限为0.029 ng/mL,定量限为0.097 ng/mL。采用方法对实际样品进行测定,回收率(n=11)为94%～104%,相对标准偏差(RSD,n=11)为0.56%～5.82%。     

原子吸收光谱法间接测定萤石中的全硫

基于SO42-和BaCrO4溶液反应生成BaSO4沉淀, 置换出定量的CrO42-, 通过原子吸收法测定Cr, 建立了间接测定萤石中硫的原子吸收光谱法. 方法的工作曲线范围0.05～20 μg/mL SO42-, 检出限为0.017 μg/mL S, 适用于硫质量分数在0.01%～3%范围内萤石样品的测定.     

复合应力场剪切诱导成型PP-R自增强管材的结构与性能研究

利用自行设计制造的剪切拉伸双向复合应力场挤管装置生产出了双向自增强的无规共聚聚丙烯(PP-R C180)管材,研究分析了该双向应力场的剪切诱导效应对PP-R C180管材的结晶熔融、取向和拉伸强度的影响.结果表明,剪切拉伸双向复合应力场的引入所带来的剪切诱导效应促进了PP-R C180分子有序性的增加,使PP-R C180体系分子更容易形成分别沿管材周向和轴向方向的取向,因而保持甚至提高了耐热性与结晶速率,降低了结晶度,改变了PP-R C180的结晶结构与形态,诱导出了全新的β晶,进而改善了管材的强度性能.与常规管材相比,自增强管材在保持其熔点不降低的前提下,使结晶度从常规管材的44.96%降至40.03%,降低了4.93%;轴向强度从常规管材的23.35 MPa最高增强到25.49 MPa,提高了9.2%;周向强度从常规管材的22.71 MPa最高增强到26.54 MPa,提高了16.9%,且增强之后管材的周向强度已经高于了轴向强度,更优化地配置了聚合物材料的性能,更充分地满足了受内压管材使用的现实需求.     

膨润土负载壳聚糖制备吸附剂

将壳聚糖与膨润土混合制得一种吸附剂。将其用于染料溶液的脱色、陈醋的澄清、中药注射液中鞣酸的清除等,脱色率为97％,鞣酸脱除率为50％,陈醋的透光率为25．8％。通过X射线衍射图讨论了膨润土的改性机理。改性后膨润土的片状层结构未发生变化,壳聚糖仅仅吸附在膨润土的内外表面。     

Stress studies on acyclovir

Acyclovir is an antiviral drug of choice in the treatment of many types of herpes virus infections, including genital herpes simplex infections, herpetic conjunctivitis, herpes simplex encephalitis, etc. The present study describes the degradation behavior of acyclovir under different International Conference on Harmonization recommended stress conditions (hydrolysis, oxidation, photolysis, and thermal decomposition) in order to establish a validated stability-indicating high-performance liquid chromatography method. Acyclovir is found to degrade extensively in acidic conditions and oxidative stress. Mild degradation of the drug occurs in alkaline and neutral conditions. The drug is stable to dry heat. The drug is found to be sufficiently stable after light exposure in a solid state; however, photolytic degradation is observed when the drug is exposed as a solution in water. The major degradation product in acidic hydrolysis and photolysis is identified as guanine through comparison with the standard. Separation of drug and the degradation products under various conditions is successfully achieved on a C-18 column utilizing water-methanol in the ratio of 90:10. The flow rate is 1 mL/min, and the detection wavelength is 252 nm. The method is validated with respect to linearity, precision, accuracy, selectivity, specificity, and robustness. The mean values of slope and correlation coefficient are 39.307 and 0.9998 with relative standard deviation values less than 2%. The recovery of the drug is found to be in the range of 97.34% to 102.35%. From the previous study it is concluded that the stability-indicating method developed for acyclovir can be used for analysis of the drug in various stability samples.     

An improved LCAO SCF method for three-dimensional solids and its application to polyethylene,graphite, diamond,and boron nitride

An improved semi-empirical self-consistent scheme is described for calculating the band structures of three-dimensional solids. The basic level is that of CNDO theory. The non-orthogonality of the Bloch functions is recognised and allowance is made for all degrees of involvement of the overlap matrix. The calculation of the electron-repulsion integrals is formulated in a way suitable for solid-state problems. The method is tested on the standard systems; polyethylene, graphite, diamond, and hexagonal and cubic boron nitride. It is found that the valence band properties are satisfactorily reproduced. For optical spectra a configurational interaction scheme is required.     

便携式亚铁离子光化学传感器的研究

研究了一种以吸附树脂为基质的便携式光化学传感器。以４,７－二苯基－１,１０－二氮杂菲为敏感试剂,用于水中亚铁离子含量的检测。此传感器结构简单,可用１２Ｖ电池提供能量,响应时间短（〈１０ｍｉｎ）,质量浓度的检测范围为０．０５～３．００ｍｇ／Ｌ,检出限为０．０１ｍｇ／Ｌ,选择性好,适用于野外水质监测。     

Multivariable kinetic theory of the first order phase transitions

The problem of calculation of the steady state homogeneous nucleation rate in the multidimensional space of the variables describing a nucleus is considered. Within the framework of the theory proposed, expressions for the nucleation rate and the steady state distribution function of nuclei are derived. The expression for the nucleation rate is invariant with respect to the space dimensionality and, in particular, involves the result of the one-dimensional theory. The distribution function is obtained in the initial, physical variables. In connection with the analysis of restrictions on the current direction, the question of symmetry of the matrix of diffusivities is considered; on the basis of the detailed balance principle it is shown that this matrix is symmetric. The question of normalizing the equilibrium distribution functions is investigated and the physical picture of the equilibrium state is described. The procedure of reducing the multidimensional theory to the one-dimensional one is described.     

Flow injection analysis of sulphite by gas-phase molecular absorption UV/VIS spectrophotometry

A flow injection gas-phase molecular absorption spectrophotometric method is described for the determination of sulphite in aqueous solution. The sulphite solution, 200 microl, is introduced into a stream of distilled water. The carrier stream containing a sulphite zone is reacted, in the first mixing coil, with a stream of sulphuric acid (1 M). The evolved sulphur dioxide is purged to the segments of nitrogen flow through the second mixing coil. The gaseous phase is separated from the liquid stream by the use of a purpose built gas-liquid separator and then is swept into a purpose built flow-through cell. The absorbance of the gaseous phase is measured at 200 nm using a UV/VIS spectrophotometer. Up to 440 microg of sulphite is determined. The limit of detection is 0.8 microg and the R.D.S. for the determination of 70 and 220 microg of sulphite are 1.02 and 0.76%, respectively. Up to 40 samples h(-1) can be analyzed. The effect of several anions and cations on the determination of sulphite was studied and the results showed that the method is relatively free from interferences. The proposed method was applied to the determination of sulphite in a synthetic sample, water sample and lemon juice.