Complexometric determination of magnesium oxide in flyash blended cement

A complexometric titration method is proposed to determine magnesium oxide in flyash blended cement. A 0.50 g of sample was heated with hydrochloric acid for 10 min. The solution was diluted to 500 ml, and 50 ml was pipetted and heated to boiling with 2.5 ml of 5% ammonium oxalate solution. The solution was then made alkaline by ammonium hydroxide. The suspension was cooled and filtered. The filtrate was titrated by standard 0.002M EDTA solution. The concentration of MgO in sample was calculated. The flyash content of the sample was determined by British Standard method and the recovery factor (f) was calculated by the equation of f = 100/(99 - 0.315 x %FA). Concentration of MgO in sample was corrected by multiplying the recovery factor with concentration initially found by EDTA titration. The precision of the method is better with more time saving than the official methods.     

聚氯乙烯表面共价键合肝素及抗凝血性的研究

采用Ar等离子体引发聚乙二醇(PEG)在聚氯乙烯(PVC)表面固定化,进一步对固定PEG后的PVC进行肝素化处理,以改善PVC材料的抗凝血性能。探讨了PEG浓度对Ar等离子体固定化反应效果的影响。通过X射线光电子能谱(XPS)、衰减全反射红外光谱(ATR-FTIR)、扫描电镜(SEM)和接触角测定研究了固定PEG前后PVC的表面性能和表面形貌的变化。XPS分析证实肝素已成功地共价键合于PVC表面。采用体外凝血时间测定和血小板粘附实验对材料的抗凝血性能进行评价,结果表明,被修饰PVC材料的抗凝血性能显著提高。     

尿样中海洛因代谢物的检验

使用自制的固相微萃取装置,对尿液中海洛因代谢物6－单乙酰吗啡进行萃取,在装有衍生化试剂的密封玻璃瓶内顶空衍生,用GC－MS检测,取得了较好的效果。方法简便、快速,可用于吸毒者的确认。     

Investigation of the origin of archaeological glass artefacts by means of pattern recognition

The origin of medieval glass artefacts is studied by using a supervised learning technique, which is shown to be helpful when samples cannot be identified by typical design and appearance. A set of seventy pieces of glass was analyzed for ten trace elements by optical emission spectrography. The data matrix of 33 known objects from five origins was evaluated by multivariate variance and discriminant analysis in a training step. The extracted non-elementary discriminant functions were used to classify the 37 unidentified samples. The classification result is discussed in terms of its cultural/historical information content.     

Stability of nanodispersions: a model for kinetics of aggregation of nanoparticles

In the course of aggregation of very small colloid particles (nanoparticles) the overlap of the diffuse layers is practically complete, so that one cannot apply the common DLVO theory. Since nanopoarticles are small compared to the extent of the diffuse layer, the process is considered in the same way as for two interacting ions. Therefore, the Br?nsted concept based on the Transition State Theory was applied. The charge of interacting nanoparticles was calculated by means of the Surface Complexation Model and decrease of effective charge of particles was also taken into account. Numerical simulations were performed using the parameters for hematite and rutile colloid systems. The effect of pH and electrolyte concentration on the stability coefficient of nanosystems was found to be more pronounced but similar to that for regular colloidal systems. The effect markedly depends on the nature of the solid which is characterized by equilibrium constants of surface reactions responsible for surface charge, i.e., by the point of zero charge, while the specificity of counterions is described by their association affinity, i.e., by surface association equilibrium constants. The most pronounced is the particle size effect. It was shown that extremely small particles cannot be stabilized by an electrostatic repulsion barrier. Additionally, at the same mass concentration, nanoparticles aggregate more rapidly than ordinary colloidal particles due to thier higher number concentration.     

Kinetics of vinyl fluoride polymerization

Vinyl fluoride was polymerized, at low temperatures and pressures, by photo- and γ-ray initiation. The kinetics of this heterogeneous polymerization reaction was studied and a general scheme was proposed to explain the experimental results. The scheme is based on the assumption that the main site of the polymerization is in the “polymer phase.” The solvent used determines the rate of the reaction by its effect on the swelling of the polymer. The degree of polymerization is determined mainly by transfer reactions.     

Photoinduced ionic polymerization. II. Cationic polymerization of α-methylstyrene in the presence of tetracyanobenzene

The dependence of the rate of polymerization on light intensity and the stereoregularity of the polymer was studied to elucidate the propagation and termination mechanisms of the photoinduced cationic polymerization of α-methylstyrene in the presence of tetracyanobenzene in methylene chloride. The rate of polymerization was proportional to the light intensity. The polymer is highly syndiotactic, and the stereoregularity is similar to that of polymers obtained by radiation-induced cationic polymerization. The initiation mechanism was also studied by electron spin resonance, by which the anion radical of tetracyanobenzene formed from a photoexcited complex between α-methylstyrene and tetracyanobenzene was observed. The cation radical of α-methylstyrene, counterpart of the anion radical, is believed to initiate the polymerization.     

三通道气相色谱法测定炼厂气组成

炼厂气是炼油工艺产生的各种气体的混合物,采用四阀六柱将炼厂气分离分解为3部分,以双TCD+FID检测器3通道气相色谱法快速分析炼厂气.FID通道用于分析烃类,一个TCD通道分析永久性气体和硫化物,另一个TCD通道分析氢气,采用面积归一化法定量计算分析结果.用该法测定了3种标准气体,测定值与标准值基本一致,测定结果的相对标准偏差小于8％.该法适用于测定包括液化气、烟气、裂解气等组分相近的样品组成.     

容量法测定氧化钒中的各种价态钒

用NaOH溶液处理样品，分离V（V）然后以Fe(Ⅱ）滴定测定之。定量加入过量的V（V）到上述残渣中并用H2SO4溶解，用Fe(Ⅱ）滴定，计算出V（Ⅱ），V（Ⅲ）的含量。V（Ⅳ）的测定是通过从总钒量中扣除V（Ⅱ）、V（Ⅲ）、V（Ⅴ）的含量得到。V（Ⅱ）、V（Ⅲ）和V（Ⅴ）的回收率均大于96％，其8次测定结果的相对标准偏差分别为：9．8％、0．4％、1．2％；本法快速、简便，在实际应用中效果良好。     

Characteristics of a protein error in determination of serum protein in the presence of inorganic salt.

There is a possibility that the color development of the dye-binding method based on a protein error of a pH indicator is affected by the coexisting inorganic salt. Thus, the author theoretically and experimentally investigated the effect of the inorganic salt on the protein error. In a theoretical analysis, the anion of an inorganic salt, like the dissociated dye and buffer anions, was assumed to react with the protein, forming a colorless anion-protein complex. The calculated results were compared with those obtained by experiments using three pH indicators and various kinds of inorganic salts. The calculated results obtained are as follows: (1) The color development decreases with increasing the concentration of the inorganic salt and the equilibrium constant of the reaction between the inorganic salt and protein; (2) The rate of the absorbance decrease is larger for a lower concentration of the inorganic salt than for a higher one; (3) The larger is the equilibrium constant, the larger is the absorbance decrease. The absorbance decrease was caused by the anion, and was increased by increasing the anion concentration. The magnitude of the effect of the anion was iodide > bromide > chloride, which was associated with their ionic radius. The difference in the effect of the anion was thought to indicate that the equilibrium constant, in other words, the bonding strength of the anion to protein is iodide > bromide > chloride.     

The influence of the adsorption of surface active substance on the rate constant of the electrode reaction

The electrode reaction of copper-EDTA complex was studied polarographically in the presence of polyvinylalcohol. The d.c. polarographic current-time curves were analyzed by using the equation given by Matsuda for the diffusion process of the depolarizer influenced by the adsorbates. The rate constants affected by the adsorption are assumed to be composed of two parts at relatively high coverage, i.e., one is the rate constant of the electrode reaction at free surface of DME and the other the rate constant of the electrode reaction through the adsorded layer. The rate constant at the uncovered surface was analyzed by a formula analogous to that proposed by Parsons and it was shown that one of the parameters involved in the formula depends on the electrode potential. On the other hand, it was shown that the electrode reaction at the covered surface is irreversible, and its cathodic rate constant depends on the electrode potential exponentially.     

几种建筑材料的氡射气系数研究

通过天然γ能谱测量方法测定建材样品中的镭含量,计算理论上衰变产生的氡密度,以及用硫化锌闪烁法测定由样品释放到空气中的氡密度的方法来计算氡的射气系数。通过改变样品的颗粒度大小,以及改变样品的灼烧温度等条件,来研究氡射气系数的变化规律。结果表明,土坯砖射气系数在8.5%~29.4%,红砖射气系数在0.031%~3.5%之间,瓷砖射气系数在0.74%~4.5%之间;建筑材料的氡射气系数随着其自身颗粒度的增大而减小,随加工(灼烧)温度升高而减小。     

Chromatographic analysis of the trinitrophenyl derivatives of insulin

The insulin molecule was derivatised by reaction with trinitrobenzenesulphonic acid (TNBS), which is known to react predominantly with free primary amino groups. The products of the reaction were analysed by reversed-phase chromatography and by further derivatisation with dansyl chloride. Under the conditions of these experiments, TNBS was found to react preferentially with glycine at position A1. This finding is discussed in terms of the tertiary structure and immunogenicity of this derivative.     

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%。     

A Study of the Molecular Weight and Chain Length Distribution of Cyclocopolymers of Divinyl Ether and Maleic Anhydride

Some physical properties of a cyclocopolymer formed by an intra-inter-molecular polymerization mechanism were studied. The cyclic copolymer of divinyl ether and maleic anhydride was chosen for study. Intrinsic viscosities were determined in two solvents. The weight-average molecular weight was determined by light-scattering measurements and the number-average molecular weight was determined by osmometry. Results from a sedimentation velocity pattern indicated that the chain length distribution is much broader than random, which is in agreement with the ratio of the two molecular weight determinations. The polymer was fractionated by precipitation from acetone with hexane as precipitant. Addition of sodium tetraphenyl boron was necessary to obtain separation. Correlation of intrinsic viscosity and weight-average molecular weights was not obtained because of anomalous solubility effects preventing light-scattering determinations.     

An insight into the process of tablet formation of microcrystalline cellulose

The present paper aims to show whether the shrinking of the microcrystalline cellulose (MCC) tablets can be derived from underlying processes and whether these processes can be visualized on a nanoscale level. Tableting of MCC was performed on an instrumented eccentric tableting machine to a maximum relative density (ρ_rel,max) of 0.90 of the tablets. The apparent density of the tablets was analyzed by helium pycnometry after tableting. The breaking surface of a MCC tablet was analyzed directly after tableting continuously by video in an environmental scanning electron microscope (ESEM) at constant humidity. Further the breaking surface was analyzed by transmission electron microscopy (TEM) after freeze fracturing. The results show that firstly apparent density by helium pycnometry increases after tableting and that secondly inside the tablet the fiber strength decreased while also the gaps between the fibers increased as was visualized by ESEM. Further the results by TEM indicate that the decrease in fiber strength is caused by a parallel orientation of the MCC microcrystals which is induced by a mechanical activation due to tableting. In conclusion the measured shrinking MCC tablets after tableting is caused by processes on a nanoscale level.     

Light Regulation of Phytochrome Content in Wild-type and Aphototropic Mutants of the Moss Ceratodon purpureus

In filaments of the moss Ceratodon purpureus , phototropism is controlled by the photoreceptor phytochrome. Thirty-three aphototropic mutants with a proposed defect in phytochrome-chromophore biosynthesis were isolated and analyzed. The phototropic response of those mutants was rescued with the precursor of the phytochrome chromophore, biliverdin. Phytochrome spectral activity was measured in 19 arbitrarily chosen mutants. All contained low but still measurable quantities of photoactive phytochrome; the highest level was around 15% of the wild-type. The level of total phytochrome (apophytochrome and holophytochrome) as assayed by immunoblotting was indistinguishable from wild-type. The content of photoactive phytochrome in Ceratodon is light-regulated. Phytochrome of wild-type kept for 24 h in red light was reduced to 50% as compared to dark controls but was unaffected by blue. The red-light-induced decrease was partially reversible by far-red light, indicating that phytochrome itself is the photoreceptor for this response. This regulation was further analyzed with the mutant ptr114 , which contains 15% photoactive phytochrome as compared to the wild-type. In this mutant, continuous red light given for 6 days decreased the level of spectrally active phytochrome down to 25% of dark controls, whereas the amount of phytochrome found on immunoblots was hardly reduced. This indicates that the loss of phytochrome affects only the holoprotein and implies that Ceratodon phytochrome is specifically degraded as a far-red-absorbing phytochrome.     

Identification of salicylic acid using surface modified polyurethane film using an imprinted layer of polyaniline

The surface of polyurethane (PU) was modified by coating a thin layer of polyaniline (PAN) by oxidizing aniline using ammonium persulfate. Affinity sites for salicylic acid (SA) were created in the coated layer by non-covalent imprinting method. The imprinted layer adsorbed SA five times more compared to the nonimprinted surface reflecting the creation of affinity sites specific to SA on the surface. The equilibrium was attained relatively faster indicating that a material of this kind is suitable for sensing applications. The selectivity in recognizing the print molecule by the imprinted surface was assessed by comparing the extent of uptake of other structurally resembling molecules namely O-amino benzoic acid and acetyl salicylic acid. The selectivity factor was found to be 22 and 16.5. The adsorbed SA was detected using the technique of Fourier transform attenuated total internal reflection infrared spectroscopy (FT-ATR-IR). The results show that molecularly imprinted surface in combination with FT-IR is a useful approach for the sensing applications.     

Determination in plasma of angiotensin-converting enzyme inhibitor by inhibitor-binding assay.

A method of determining a new angiotensin-converting enzyme inhibitor (CS-622) and its active metabolite (RS-5139) in plasma by inhibitor-binding assay has been developed using high-performance liquid chromatography. The assay is based on the principle that the amount of inhibitor bound to the enzyme is inversely related to the amount of hippuric acid liberated on hydrolysis from the artificial substrate (hippuryl-L-histidyl-L-leucine). Plasma was heated at 60 degrees C for 15 min, to inactivate endogenous enzyme, and preincubated with rabbit-lung angiotensin-converting enzyme at 37 degrees C for 3 min. The artificial substrate (5.75 mg/ml in pH 8.3 phosphate buffer containing sodium chloride) was added to the resulting solution, and the mixture was incubated for 30 min. The reaction was terminated by the addition of 2 M hydrochloric acid. The hippuric acid liberated on hydrolysis was extracted with ethyl acetate and determined by reversed-phase chromatography using methylparaben as an internal standard. The total concentration of the inhibitor and its metabolite were determined by this method after de-esterification by rat-plasma esterase. The standard curve was obtained by the regression analysis of log concentration against logit response. The within-day and day-to-day precision were satisfactory. The proposed method is simple, rapid and sensitive enough to determine angiotensin-converting enzyme inhibitor in plasma.     

Polymerization of aromatic nuclei. XVI. Mechanism of chain propagation in the polymerization of benzene by aluminum chloride–cupric chloride

A study was made of the mechanism of benzene polymerization by aluminum chloride-cupric chloride. Our main effort was devoted to propagation with the aim of resolving a literature conflict as to whether a cationic or radical pathway is involved. When equimolar mixtures of benzene and haloarene are polymerized, the resulting copolymers are composed almost exclusively of benzene monomer. This approach is based on the known relative reactivities of the monomers toward electrophilic and radical species. The amount of haloaromatic present in the copolymer was determined by elemental analyses and confirmed by infrared spectroscopy. These results are strongly indicative of propagation by an electrophilic moiety. The presence of oxygen in the reaction mixture was found to have no significant effect on the rate or yield of the polymerization, in contrast to a previous published report. The progress of the reaction was followed by titration of the evolved hydrogen chloride. Phenyl radicals, obtained by the thermal decomposition of benzoyl peroxide in benzene, were found to be incapable of initiating the polymerization in the presence of cupric chloride. Increased yields of biphenyl and the presence of chlorobenzene point to oxidation of intermediate radicals by cupric chloride. None of the experimental evidence is satisfactorily interpreted by radical propagation. The data are nicely rationalized on the basis of cationic chain extension, apparently via a radical cation initiator.