Studies on the phase properties of lyotropic liquid crystals of Brij35/sodium oleate/oleic acid/water system:By means of polarizing microscope,SAXS,~2H-NMR and rheological methods

The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, 2H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA′ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively.     

Studies on the phase properties of lyotropic liquid crystals of Brij35/sodium oleate/oleic acid/water system: By means of polarizing microscope, SAXS, 2H-NMR and rheological methods

The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, ²H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA’ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively.     

Study on Schiff base complexes-cellular DNA interactions by a novel system of Hadamard transform fluorescence image microscopy

A novel system of Hadamard transform microscopic fluorescence imaging for single cells is presented, based on which the DNA ploidy of rat hepatocyte was quantitatively measured. The result shows that diploid rat hepatocyte has a stable DNA content, thus diploid rat hepatocyte was used to investigate the binding of five clinical anticancer agents, vincristine, cyclophosphamide, nitrogen mustard, cis-diamminedichloroplatinum(n) (CDDP) and mitomycin-C, with cellular DNA when acridine orange (AO) was used as the competitive fluorescence probe. Based on this model, some Schiff base complexes-cellular DNA interactions were investigated. The results indicate that all the twenty-two compounds, including Schiff base ligands of N-2-hydroxy-naphthaldehyde with D-glucoamine (NG) and the complexes of 3d-transitional metals ions with NO and with D-glucoamine (Glu) and the mixed complexes of NG and Glu series with alpha-glycine (GNG), have the ability to enter the cell membrane and interact with cellular DNA. Four of the compounds, CuGlu, Fe(II)NG, Fe(III)NG and CuGluG can intercalate with DNA like AO does and depress AO-DNA fluorescence to 70% or lower. An in intro UV-visible spectroscopic study on the compound-DNA spectra testified the above results and suggests that diverse interaction mechanisms coexist for all these complexes except intercalating mode. This study presents a new in vitro method for initial screening of anticancer compounds.     

Chromatographic screening for drugs of abuse using capillary columns II. Peak identification on support coated open tubular columns for a series of central nervous system stimulant drugs

Summary A system based on Kovats' Retention Indices is described for the identification of CNS stimulant drugs recovered from body fluids. Use is made of the difference in retention indices found on polar and non-polar GLC columns (l values) and the effect of operating temperature is discussed.     

Hydrogen desorption mechanism in a Li-N-H system by means of the isotopic exchange technique

The hydrogen desorption mechanism in the reaction from LiH + LiNH2 to Li2NH + H2 was examined by thermal desorption mass spectrometry, thermogravimetric analysis, and Fourier transform IR analyses for the products replaced by LiD or LiND2 for LiH or LiNH2, respectively. The results obtained indicate that the hydrogen desorption reaction proceeds through the following two-step elementary reactions mediated by ammonia: 2LiNH2 --> Li2NH + NH3 and LiH + NH3 --> LiNH2 + H2, where hydrogen molecules are randomly formed from four equivalent hydrogen atoms in a hypothetical LiNH4 produced by the reaction between LiH and NH3 according to the laws of probability.     

Direct measurement of conformational changes on DNA molecule intercalating with a fluorescence dye in an electrophoretic buffer solution by means of atomic force microscopy.

By means of atomic force microscopy (AFM), we performed the direct imaging of DNA molecules (200, 500, 1000 bp) in a Tris-borate buffer solution, and measured the contour length and the end-to-end distance of DNA. Processing the data according to the worm-like chain model, we calculated the persistence length of the double-stranded DNA. Based on the analysis of the contour length and the persistence length, we discussed the interactions between DNA and an intercalating fluorescence dye (YO-PRO-1). YO-PRO-1 stacks between the base pairs and extends the contour length of DNA, changing the electric charge and the persistence length of DNA. From AFM measurement, we investigated directly the relationship between the persistence length and the number of the YO-PRO-1 intercalating to DNA. We will discuss on the relationship between the effect of an intercalating dye on the electrophoretic behavior and the conformational changes of DNA with an intercalating dye.     

Polysaccharides ofPolygonatum. VI. A study of the structure of a glucomannan fromPolygonatum sewerzowii by13C NMR spectroscopy,electron microscopy,and x-radiography

A phytoecdysteroid, sileneoside D, has been isolated from the roots ofSilene brahuica Boiss. and it has been shown to be ecdysterone 3-O--D-galactopyranoside.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 741–744, November–December, 1984.     

Study of corrosion on copper strips by petroleum naphtha in the ASTM D-130 test by means of electronic microscopy (SEM) and energy dispersive X-ray (EDX)

Summary Corrosion in heat-engines has been attributed to some undesirable sulfur compounds present in petroleum naphthas, fuel-oils or gasolines. The corrosivity of these petroleum products is measured by means of the ASTM D-130 copper strip test, which is based on discoloration of a standard copper strip immersed into the petroleum products at 50°C for 3 h. The present paper studies various aspects of corrosivity of different sulfur compounds in petroleum naphthas by means of the ASTM D-130 test together with the electronic microscopy (SEM) and energy dispersive X-ray (EDX) techniques. These non-destructive techniques allow to know the strip corrosive morphology and to determine the sulfur concentration on this strip. Of the various types of sulfur compounds present in petroleum naphthas, the data show that elemental sulfur is corrosive to copper, but its corrosive level differes from naphtha to naphtha. Among the different mercaptans only ethyl-mercaptan presents corrosivity. The disulfides and sulfides tested are non-corrosive to copper.     

Analysis of interferents by means a D-optimal screening design and calibration using partial least squares regression in the spectrophotometric determination of Cr(VI)

Using a central composite design, the signal of the process for the spectrophotometric determination of hexavalent chromium (λ = 543 nm) is maximised and its variability minimised using as complexing agent 1,5-diphenylcarbazide in sufficiently acid medium. To analyse the interference of various analytes (Mo(VI), V(V), Fe(III) and Mn(VII)) on the Cr(VI) as a function of concentration of interferent, a factorial design was prepared at three levels of each (zero, medium and high concentration), which implies performing 81 determinations. However, a D-optimal design with just nine experiments is sufficiently good to estimate the model proposed.The interference of these metals makes it impossible to determine Cr(VI) when they are present in the sample. To avoid prior separation steps, a multivariate regression by partial least squares, PLS, is proposed to calibrate the Cr(VI) in the presence of these analytes varying the concentration of the Cr(VI) between 0.1 and 0.9 μg ml⁻¹ and that of the interferents between 3 and 5 μg ml⁻¹. The average errors obtained were 4.5% and 3.29% fitted and in prediction, respectively, with a standard error in prediction (RMSEP) of 0.016% presenting absence of both constant and proportional bias.The detection limit with the PLS regression in the presence of interferents is 0.1 μg ml⁻¹ with a probability of false positive equal to 5% and less than 5% for false negative. The capability of detection is similar to that obtained with the univariate calibration (absorbance at 543 nm) in absence of interferents.With the PLS regression it is possible to discriminate 0.085 μg ml⁻¹ of Cr(VI) in a sample with 0.5 μg ml⁻¹ of Cr(VI) with probabilities of false compliance and false non-compliance equal to 0.05. For the univariate calibration without interferents, it was established at 0.0971 μg ml⁻¹ of Cr(VI) for the same nominal concentration.In relation to interference of V(V), Fe(III) and Mn(VII), the PLS calibration could be an efficient alternative to the separation step for Cr(VI) spectrophotometric determination using 1,5-diphenylcarbazide.     

Quantitative validation of a flow-injection determination of penicillin in pharmaceutical formulations by means of a validation program based on an expert system

The quantitative validation of the results of a flow-injection determination of penicillin in pharmaceutical formulations is described. The validation procedure is done by using VALID, which is a generally applicable validation program based on an expert system program. The automated penicillin assay is based on the enzymatic hydrolysis of the penicillin to the corresponding penicilloic acid, which reacts with iodine generated on-line; the iodine consumption is detected amperometrically. The method is evaluated for applicability in pharmaceutical quality control. The complete validation procedure is described. During the program run, the system evaluates the calibration procedure, the drift of the analytical systemm and the effect of the sample matrix. The reliability of the flow-injection method is estimated by evaluating the maximum total error (MTE), which includes both random error and systematic error. The latter was assessed by comparing of the results of the flow-injection method with the results obtained by titration with mercury(II) as the reference method. The user requirement for the assay was an MTE of 10%. The validation procedure showed that the analytical method complied with the requirements for the major part of the concentration range (0.066–0.25 mM).     

Automated determination of molybdenum(VI) in seawater by means of constant-current reduction of the adsorbed 8-quinolinol complex in a computerized flow potentiometric stripping analyzer

Molybdenum(VI) in seawater is determined by means of potentiostatic adsorption of the 8-quinolinol complex onto a mercury film electrode at ?0.2 V vs. SCE and subsequent reduction of the complex by means of constant-current stripping in 5 M calcium chloride medium with a fully automated stripping analyzer. A single stripping peak at –0.42 V vs. SCE was obtained. The molybdenum(VI) concentration in reference seawater NASS-1, with a certified value of 11.5 ± 1.9 μg 1^?1, was found to be 8.9 ± 1.3 μg 1^?1 (n = 10).     

X International Conference on Zeolites. New results and tendencies in the field of synthesis,study, and application of microporous crystalline materials

Information Congresses, Conferences, Symposia, Workshops, and Seminars in the Field of Chemical Sciences Held with Participation of the Russian Academy of Sciences

X International Conference on Zeolites. New results and tendencies in the field of synthesis, study, and application of microporous crystalline materials     

Release from or through a wax matrix system. VI. Analysis and prediction of the entire release process of the wax matrix tablet

Analysis of the entire release process of the wax matrix tablet was examined. Wax matrix tablet was prepared from a physical mixture of drug and wax powder to obtain basic or clear release properties. The release process began to deviate from Higuchi equation when the released amount reached at around the half of the initial drug amount. Simulated release amount increase infinitely when the Higuchi equation was applied. Then, the Higuchi equation was modified to estimate the release process of the wax matrix tablet. The modified Higuchi equation was named as the H-my equation. Release process was well treated by the H-my equation. Release process simulated by the H-my equation fitted well with the measured entire release process. Also, release properties from and through wax matrix well coincident each other. Furthermore, it is possible to predict an optional release process when the amount of matrix and composition of matrix system were defined.     

Study of radiation-induced polymerization of vinyl monomers adsorbed on inorganic substances. X. Influence of H2O on the styrene–silica gel system

To elucidate the reaction mechanism of radiation-induced polymerization of the styrene—silica gel system, the influence of H₂O as adsorbed water and inhibitor of cationic polymerization was investigated by two methods. Monomer conversion decreased as H₂O increased. In general, percent grafting decreased as H₂O increased, but the presence of a small amount of H₂O increased the percent grafting. Grafting at 16 Mrad has a maximum value at a water content of about 0.2%. This seems to be due to two effects of H₂O: percent grafting increases due to restraint of cationic polymerization by H₂O, but the percent grafting decreases due to adsorption water which interrupts the contact of styrene with silica gel. In GPC spectra, the low molecular weight peaks of both graft polymers and homopolymers decreased when H₂O was added. The GPC results suggest that the number of positive holes which initiate cationic polymerization is very large.     

Study of the VirE2-ssT-DNA complex formation by scanning probe microscopy and gel electrophoresis- T-complex visualization.

The recombinant virulence protein VirE2, capable of forming a complex with single-stranded T-DNA during transfer into plant cells, was isolated, purified, and used for interactions with ssT-DNA. The in vitro interaction of VirE2 and ss-binding protein from Escherichia coli with single-stranded DNA (phage lambda) was determined by agarose gel electrophoresis by the formation of high-molecular-weight complexes after preliminary coincubation of purified protein preparations with ssDNA. We show that VirE2 binds to single-stranded DNA and protects it against nuclease S1 degradation much better than does E. coli SSB protein. We for first time observed the VirE2-ssT-DNA complex by using atomic force microscopy. The complex observed by atomic force microscopy after ssT-DNA and VirE2 protein mixing has a length of about 800 nm and a 5-8 nm width in sites with attached VirE2 protein.     

光谱法研究CTAB与PAN复合过程的热力学性质

近年来,表面活性剂胶束和微乳液增溶光度法的应用及机理已作了较为深刻的研究[1-3],本文将通过紫外分光光度法考察十六烷基三甲基溴化铵CTAB与有机显色剂PAN复合反应的热力学性质,从而为光度比色分析条件的选择提供一定的理论依据。1　实验方法ShimadzuUV 240型紫外分光光度计(北京市通用仪器设备公司);CS 501型超级恒温器(重庆试验设备厂);AE204电子天平(梅特勒 托利多仪器〈上海〉有限公司)。0 02%的1 (2 吡啶偶氮) 2 萘酚(PAN)乙醇溶液;0 0200mol·dm-3的Sigma公司生产的十六烷基三甲基溴化铵(CTAB)水溶液,HAc NaAc缓冲溶…