聚酯酰胺的合成及表征

用两种方法合成了聚酯酰胺（ＰＥＡ）共聚物．一种是两步法，即先合成对苯二甲酸乙醇酰胺（ＢＡＥＴ）单体，然后与对苯二甲酸乙二酯（ＢＨＥＴ）共缩聚；另一种是一步法．即在酯交换反应中直接添加乙醇胺（ＥＡ）．两种方法制得的聚酯酰胺（ＰＥＡ）共聚物测试证明了为产物，并分析了合成中的化学反应．     

芴取代的有机膦化合物的合成及发光性能

合成了以芴为取代基，P原子为核的一类新型有机膦化合物．此类化合物的HOMO值在-5．35～-5．24eV之间．在二氯甲烷中的最大紫外吸收光谱峰值在313～351nm之间，荧光光谱峰值在334～397nm之间．利用此类小分子与纯聚芴进行掺杂，制作了有机电致发光器件．低HOMO值有机膦化合物的引入有效地降低了聚芴发光器件的开启电压，提高了器件的发光效率．     

Microcomputer application of non-linear regression analysis to metal-ligand equilibria

A non-linear least-squares regression program is described which is suitable for PC-compatible microcomputers. The program is written in GWBASIC, but compiled to run with the Intel 8087 fast numeric processor. Subroutines which simulate functions are compiled separately from the main program. Parameters are optimized by a Gauss-Newton-Marquardt algorithm which can be provided with either analytically or numerically calculated partial derivatives. Multi-component potentiometric titrations are simulated and parameters optimized by using analytical derivatives. Spectrophotometric titrations are also simulated, but absorptivities are optimized by linear regression while stability constants are optimized non-linearly by using numerical derivatives. Provision is made for "global analysis" of parameters. The experimental points can be displayed on screen, along with the "best" fit and the speciation. The program is demonstrated here by the determination of the pK(a) values and stability constants of a hydroxypyridinone ligand and its complexes with Fe(III).     

聚酯酰胺的合成及表征

 用两种方法合成了聚酯酰胺（ＰＥＡ）共聚物．一种是两步法，即先合成对苯二甲酸乙醇酰胺（ＢＡＥＴ）单体，然后与对苯二甲酸乙二酯（ＢＨＥＴ）共缩聚；另一种是一步法．即在酯交换反应中直接添加乙醇胺（ＥＡ）．两种方法制得的聚酯酰胺（ＰＥＡ）共聚物测试证明了为产物，并分析了合成中的化学反应．     

Production of acetone-butanol-ethanol from corn mash and molasses in batch fermentation

The production of solvents from corn mash and molasses in batch fermentation usingClostridium acetobutylicum P 262 was examined. The content of saccharose of beet molasses used in experiments is determined by using the gravimetric method (52.45% saccharose). The quantities of molasses that are used in the nutrient medium are calculated after doing the above determination. The samples of fermentation liquid are taken within a certain time, the determination of saccharose is done by using the same method, and all the saccharose is converted by the microorganism to organic end products. The quantitative and qualitative determination of acetone-butanol has been made by using gas chromatography. On the other hand, using the three isolation way, three different cultures are obtained, and with microscopic observations, the cultures obtained are of the C.acetobutylicum genus. According to the literature values, the concentration of maximum mixed solvent formed during fermentation is about 2%. This is seen in this experiment. There is only a slight difference from this value. This difference is caused by another organic product that is formed during fermentation.     

Oxidation of quinazoline and quinoxaline by xanthine oxidase and aldehyde oxidase

Quinazoline is oxidized by xanthine oxidase initially (and rapidly) to 4-hydroxyquinazoline which subsequently is oxidized more slowly to 2,4-dihydroxyquinazoline. Both oxidative reactions are inhibited strongly by allopurinol. Quinazoline is oxidized by aldehyde oxidase to 4-hydroxyquinazoline but within a short time (3–5 minutes) the reaction ceases; the proposal that cessation of reaction is due to product inhibition is rendered untenable by our observation that 4-hydroxyquinazoline is rapidly oxidized by aldehyde oxidase to 2,4-dihydroxyquinazoline. Preincubation of aldehyde oxidase with quinazoline results in complete inhibition of the ability of the enzyme to oxidize 4-hydroxyquinazoline and the standard substrate N-methylnicotinamide. It appears therefore that quinazoline is able to react with aldehyde oxidase and inactivate it. Quinoxaline and 2-hydroxyquinoxaline are not oxidized by xanthine oxidase but are converted by aldehyde oxidase to 2,3-dihydroxyquinoxaline; all oxidations mediated by aldehyde oxidase are inhibited completely by menadione.     

Hydride affinities of some substituted alkynes: prediction by DFT calculations and rationalization by triadic formula

Hydride affinities (HAs) of the ethynes substituted by a wide range of different substituents are considered by using the B3LYP methodology. The computed values are in fair agreement with available experimental data, which are unfortunately scarce. The trend of changes of the HAs is rationalized by trichotomy formula. One of the important results of this analysis is a finding that similar HA values might result from completely different effects. Alternative sites of the H- attack are examined and the difference in energies relative to the most susceptible positions is interpreted. Structural features of substituted ethyne hydrides are briefly discussed.     

Spot-test detection of aryl hydrazines, hydrazones, osazones, oximes and aromatic amines

Arylhydrazines are detected by oxidation with N-bromosuccinimide and coupling with resorcinol to form azo-dyes which are intensely coloured in alkaline media. Hydrazones and osazones are hydrolysed to form the arylhydrazines, which are then tested for 4-Nitro- and 2,4-dinitrophenylhydrazines are tested for by forming their hydrazone with salicylaldehyde and adding alkali to produce a violet colour. The hydroxylamine formed by the hydrolysis of oximes is oxidized by iodine monochloride in the presence of sulphanilic acid; coupling with 8-hydroxyquinoline forms a dye that is red in alkali. Intense colours are immediately produced when primary, secondary and tertiary aromatic amines are mixed with diacetoxyiodobenzene. All the tests are sensitive and appear to be specific.     

Adsorption relaxation for nonionic surfactants under mixed barrier-diffusion and micellization-diffusion control

Relaxation processes of surfactant adsorption and surface tension, which are characterized by two specific relaxation times, are theoretically investigated. We are dealing with fluid interfaces and small initial deviations from equilibrium. For surfactant concentrations below the critical micellization concentration (CMC), we consider adsorption under mixed barrier-diffusion control. General analytical expressions are derived, which are convenient for both numerical computations and asymptotic analysis. Series expansions for the short- and long-time limit are derived. The results imply that the short-time asymptotics is controlled by the adsorption barrier, whereas the long-time asymptotics is always dominated by diffusion. Furthermore, for surfactant concentrations above the CMC, adsorption under mixed micellization-diffusion control is considered. Again, a general analytical expression is derived for the relaxation of surfactant adsorption and surface tension, whose long- and short-time asymptotics are deduced. The derived equations show that at the short times the relaxation is completely controlled by the diffusion, whereas the long-time asymptotics is affected by both demicellization and diffusion. The micellar effect is manifested as an exponential (rather than square-root) decay of the perturbation. The derived expressions are applied to process available experimental data for the nonionic surfactant Triton X-100 and to determine the respective demicellization rate constant.     

静电纺丝制备杯芳烃功能化纳米纤维的应用

静电纺丝技术是制备连续微纳米纤维的一种简单易行且高效的方法,所制备的纳米纤维因其独特的结构尺寸和广泛的应用领域而备受材料科学界的青睐。 作为第三代超分子主体化合物的杯芳烃及其衍生物因其独特的分子结构、优异的离子选择识别性和吸附性能而显示出广阔的应用前景。 本文简述了静电纺丝制备杯芳烃功能化纳米纤维的原理,系统地探讨了其作为吸附剂和催化剂载体的应用以及静电纺丝与杯芳烃相结合的优势。 讨论了目前静电纺丝制备杯芳烃功能化纳米纤维存在的问题,对未来的发展方向进行展望。     

Preparation of transparent,monolithic silica xerogels with low density

A new process to make monolithic and transparent silica xerogels with similar properties as silica aerogels by drying at ambient pressure has been studied. The xerogels are produced by strengthening the gel structure by additional precipitation of silica after the initial gelation. The additional precipitation of silica is achieved by ageing the alcogels in solutions of tetraethoxysilane (TEOS) and the aging is followed by a relatively rapid drying (<48 h) at ambient pressure. Due to the increased strength of the alcogels it is shown that the shrinkage during drying can be reduced and hence low density xerogels are obtained even if new monomers are added.     

Rapid determination of lead and cadmium in biological fluids by electrothermal atomic absorption spectrometry using Zeeman correction

Procedures for the electrothermal atomic absorption spectrometric determination of lead and cadmium in urine, serum and blood are developed. For serum and blood, the samples are diluted by incorporating 0.015% (w/v) Triton X-100 and 0.1% (w/v) ammonium dihydrogenphosphate to the solutions, which are then introduced directly into the furnace. A solution containing 15% (w/v) hydrogen peroxide and 0.65% (w/v) nitric acid is also introduced into the atomizer by means of a separate injection. Zeeman-based correction is recommended. Both conventional and fast-heating programs are discussed. Calibration is carried out using the standard additions method. The reliability of the procedures is checked by analyzing three certified reference materials and by recovery studies.     

Early Stages of Crystallization in Gel Derived ZrO2 Precursors

Three different precursor materials giving rise to contrasted nanostructures, xerogels, aerogels and precipitates, are prepared by a sol gel route in the Zrn -propoxide—acetylacetone—water—n-propanol system. Clear homogeneous gels are made by using a proper amount of acetylacetone and water. The gels are dried either by conventional processing (xerogels) or by supercritical evacuation of alcoholic solvent (aerogels). The complexation ratio (R = [acetylacetone]/[Zr(OR)₄]) is the main parameter controlling the size of ZrO₂ primary particles. WhenR = 0 , precipitates are obtained.Xerogels, aerogels and precipitates are characterized and their textures are compared through small angle X-ray scattering measurements. The fractal structure of gels is destroyed by conventional drying and is preserved in aerogels. On the other hand precipitates are described as homogeneous agglomerates of very small primary units.The first crystallization steps are studied by transmission electron microscopy and X-ray diffraction experiments. The contribution of crystallite size and microstrain effects are investigated by Rietveld whole pattern fitting. The crystallization of precipitate powders starts at the agglomerate scale with large crystal like distorted lattices.     

A scheme for the analysis of monazite and monazite concentrates

A scheme using ion-exchange methods is described for the analysis of monazites and monazite concentrates. The sample is opened up with concentrated sulphuric acid, and the resultant solution is applied to a column of Zeocarb 225 resin. After phosphate has been washed out, lead, aluminium, titanium, iron, uranium, calcium and magnesium are eluted with N hydrochloric acid and determined by specific, mainly spectrophotometric, methods. Rare earth elements are eluted with 3 N hydrochloric acid. Cerium is separated from the other rare earths by solvent extraction of its nitrate with methyl iso-butyl ketone; both groups are determined gravimetrically. Thorium is eluted from the ion-exchange resin with 3.6 N sulphuric acid and determined spectrophotometrically with thorin.The sulphuric acid-insoluble minerals are brought into solution by a double fusion method, and the determinations are carried out by a combination of ion-exchange and photometric procedures. Silica, phosphorus pentoxide, tin and chromium are determined by photometric methods, using separate portions of the sample.Lanthanum, yttrium and ytterbium are determined in a 1 M perchloric acid solution of the mixed rare earth oxides (less cerium) using flame photometry. Samarium, praseodymium and neodymium are determined by spectrophotometry.     

The application of strictly localized geminals to the description of chemical bonds

A theory is developed in which closed-shell molecules are viewed as systems of weakly interacting chemical bonds. Composite-particle creation operators obtained by an appropriate quasiparticle transformation are used to create the wave function of two-electron bonds. These quasiparticles are bosons, since they are composed of two electrons, but the total many-electron wave function is properly antisymmetric. The internal structure of the quasi-Bose-particles is affected by inductive interbond interactions. Delocalization and dispersion interactions between different bonds are neglected, thus the approach corresponds to a first-order many-body PT (Perturbation Theory) with a correlated, but fully localized, reference state. The whole formalism is developed ab initio. The nonorthogonality problem is handled by a biorthogonal formulation. To illustrate the effectiveness of the model, numerical calculations are reported.     

Influence of spontaneous curvature and microtubules on the conformations of lipid vesicles

The conformations of vesicles deformed by microtubules are studied within the framework of the curvature energy. The phenomenon in which the destruction of a microtubule is followed by the formation of peristaltic shapes on a protrusion created by the microtubule is investigated. The influence of the spontaneous curvature on the conformations of vesicles is examined, and the results are compared to existing experiments. The elastic properties of a vesicle deformed by the microtubule are studied.     

Small-angle scattering of polarized light. VI. Sphere doublets at rest and during shear

The polarized or depolarized light scattering by well-defined monodispersed sphere doublets is investigated. Two configurations of doublets are studied. In the first (at rest) the doublets are randomly oriented in a plane, in the second the doublets are oriented in a preferred direction. This is achieved by submitting a suspension of doublets to a shear flow. The scattering patterns are compared to two theoretical predictions based on simplified geometries. In the first approach, the doublet is approximated by two interpenetrating spheres scattering independently, whereas in the second, an ellipsoid geometry is used. A good qualitative comparison is obtained. However, the HV and VH patterns of a randomly dispersed suspension are not similar. The observation of the flow of a doublet suspension in shear shows that the doublets are spiraling around the vorticity axis. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2005–2013, 1998     

Determination of Caffeine in Small Plasma Samples by Gas-Liquid Chromatography with Thin-Layer Chromatographic Sample Clean-Up

Abstract

A sensitive method for the determination of caffeine in small plasma samples (50 μ1) is described. The samples are extracted with chloroform and the extrects are freed from interfering compounds by thin-layer chronatography. The spots of caffeine and the internal standard, 7-ethyl theophylline, are scraped off the plates and both compounds are eluted from the scrapings by means of a glass capillary collector. The caffeine in the eluate is quantitated by gas-     

Dependence on effective saturation of numbers of singlet peaks in one- and two-dimensional separations

The average numbers of singlet peaks in one-dimensional (1D) and two-dimensional (2D) separations of randomly distributed peaks are predicted by statistical-overlap theory and compared against the effective saturation. The effective saturation is a recently introduced metric of peak crowding that is more practitioner-friendly than the usual metric, the saturation. The effective saturation absorbs the average minimum resolution of statistical-overlap theory, facilitating the comparison of 1D and 2D separations by traditional metrics of resolution and peak capacity. In this paper, singlet peaks are identified with maxima produced by a single mixture constituent. Their effective saturations are calculated from published equations for the average minimum resolution of 1D singlet peaks, and from equations derived here for the average minimum resolution of 2D singlet peaks. The fractions of peaks that are singlets in 1D and 2D separations are predicted by statistical-overlap theory as functions of saturation but are compared as functions of effective saturation. The two fractions differ by no more than 0.033 at any effective saturation between 0 and 6, when the distribution of peak heights is exponential and the edge effect is neglected. This result shows that 1D and 2D separations of randomly distributed peaks are about the same in their ability to separate singlet peaks as maxima, when assessed relative to effective saturation. Empirical equations in effective saturation are reported for the fractions of peaks that are singlets. It is argued that the effective saturation is a good metric for comparing separations having different average minimum resolutions.