An experimental study of gas adsorption on fractal surfaces

The validity of the fractal versions of the FHH and BET theories for describing the adsorption of butane and nitrogen on a variety of partially dehydroxylated silica surfaces has been tested. The fractal dimensions obtained from adsorption data have been compared with those obtained completely independently using SAXS. It was found that the fractal dimensions obtained from butane adsorption isotherms, using both the fractal FHH and fractal BET theories, agreed well with the corresponding values obtained from SAXS over overlapping length scales. However, in general, a systematic deviation between the fractal dimension obtained from nitrogen adsorption and that obtained from SAXS was observed. The fractal dimensions obtained from nitrogen adsorption were consistently larger than those obtained from SAXS, which is the opposite of what has often been found in the literature. It has been suggested that the differences in the suitability of the adsorption theories tested to describe butane and nitrogen adsorption is due to the significant difference between the interaction strengths of these two different molecules with silica surfaces. A modified theory that can account for the discrepancy between the fractal dimensions obtained from nitrogen adsorption and SAXS has been proposed. The implications of the new theory for the accuracy of nitrogen adsorption BET surface areas for silicas are discussed.     

Solution crystallization of nylon 6

Electron microscopy and x-ray diffraction data have been obtained on nylon 6 which has been crystallized from solutions in 1,6-hexanediol and 1,2,6-hexanetriol. Lamellar single crystals and spherulites of the γ form are obtained by crystallization from 1,2,6-hexanetriol. The morphology of the single crystals is different from that obtained from glycerine solutions. The spherulites of the γ form are composed of larger lamellae. Sheaflike crystals of the α form are obtained from both solvents. α-form and γ-form crystals both grow from 1,2,6-hexanetriol at appropriate crystallization temperatures. α-form crystals alone are obtained from 1,6-hexanediol solution at every crystallization temperature. The long periods measured by small-angle x-ray diffraction for the solution-grown crystals are in the range 56 to 66 Å. The melting behavior of the solution-grown crystals is examined and discussed. Effects of solvent on growth of the two crystalline forms from solution are investigated.     

Solution Association Characterization of Hydrophobically Associating Polyacrylamide Obtained from Produced Fluids

The hydrophobically associating polyacrylamide (HAPAM) obtained from produced fluids with compositional homogeneity was systematically investigated by zero-shear viscosity, fluorescence, sand-pipes experiment and adsorption behavior. The results showed that HAPAM obtained from produced solution through porous media has been possession in hydrophobic association character. The critical association concentration (CAC) determined by viscosity method, fluorescence spectroscopy method and micro-pore method have no obvious change compared with the original polymer. The hydrophobic associative capability of HAPAM obtained from produced fluids was smaller than that of original HAPAM. Compared to original PAM and PAM obtained from produced fluids, HAPAM obtained from produced fluids still exhibits promising applied potential. It reveals the possibility that HAPAM obtained from produced could be re-used for enhance oil recovery.     

Synthesis of o-azobispyrazole derivatives

Azobispyrazoles were obtained by diazo coupling of diazotized o-aminoazopyrazoles. The o-azobispyrazole obtained from 3-methyl-1-phenyl-5-pyrazolone exists in the o-azohydrazone form, whereas the o-azobispyrazole obtained from 5-amino-3-methylpyrazole exists in the o-azobis form. A 3-azo derivative of naphtho[2,1-e]-pyrazolo[5,1-c]triazine is formed from 2-naphthol. The structures of the compounds obtained were confirmed by IR, UV, PMR, and mass spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 382–387, March, 1978.     

Determination of antihypertensive mixtures by use of a chemometrics-assisted spectrophotometric method

A simple multivariate calibration method for analysis of two types of hypotensive mixture is described. The mixtures are composed of chlorthalidone with atenolol or chlorthalidone with both amiloride hydrochloride and atenolol. The components of the mixtures result in substantial spectral overlap—between 87.5 and 91.0%. Resolution of the mixtures under investigation has been accomplished mainly by using CLS and PCR methods. The components in each mixture have been simultaneously determined in three commercial dosage forms with high accuracy and without interference from commonly encountered excipients and additives. Good recoveries were obtained with both synthetic mixtures and commercial tablets. The results obtained were compared with those from pharmacopeial methods and found to be in good agreement. The results obtained from CLS and PCR were also compared with those obtained from a ¹D spectrophotometric method.     

Chiral schiff bases synthesized from terpenes of pinane series in asymmetric metall complex oxidation of sulfides

The absolute configuration of α-hydroxyaldehyde obtained from verbenol epoxide in the presence of clay was determined. Two new Schiff bases were synthesized from the aldehyde obtained. The compounds can be used as ligands in the asymmetric vanadium-catalyzed oxidation of sulfides to sulfoxides. The structure of initial sulfides significantly affects the value of the enantiomeric excess in the obtained sulfoxides: the highest enantiomeric excess is observed in the oxidation of thioanisole.     

Comparison of electrodeposition of silver in ionic liquid microemulsions

Both ionic liquid (IL) and water are typical green solvents and have high electric conductivity. The use of IL microemulsions as templates and media for electrochemical synthesis of nano-materials is attractive. In this work, water-in-ionic liquid (W/IL) microemulsion and ionic liquid-in-water (IL/W) microemulsion were prepared, in which hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was used. The cyclic voltammetry (CV) behavior and electroplating in the W/IL and IL/W microemulsion systems containing silver nitrate were investigated for the first time. Both the CV curves exhibit the presence of reduction and oxidation peaks corresponding to the deposition and dissolution of silver from the two microemulsion systems. However, the CV obtained from IL/W microemulsion system exhibits a crossover, which is different from that obtained from W/IL microemulsion system. The electrodeposits obtained from W/IL microemulsion system are nano-granular, while those obtained from IL/W microemulsion system are planar. These results are attributed to the different microenvironments of the microemulsions.     

The natural constituents of historical textile dyes

The sources and structures of dyes used to colour Western historical textiles are described in this tutorial review. Most blue and purple colours were derived from indigo--obtained either from woad or from the indigo plant--though some other sources (e.g. shellfish and lichens) were used. Reds were often anthraquinone derivatives obtained from plants or insects. Yellows were almost always flavonoid derivatives obtained from a variety of plant species. Most other colours were produced by over-dyeing--e.g. greens were obtained by over-dyeing a blue with a yellow dye. Direct analysis of dyes isolated from artefacts allows comparison with the historical record.     

GC-MS analysis of aroma of Medemia argun (mama-n-khanen or mama-n-xanin), an ancient Egyptian fruit palm

The fruits of the edible and medicinal Egyptian palm, Medemia argun, were collected from Aswan in Egypt and the essential oil (EO) from fruits and headspace (HS) of the seeds and fleshy mesocarps were analyzed by GC and GC-MS. Results obtained by GC-MS analysis indicated a high variability in the oil and in the headspace from seeds and mesocarps. Sesquiterpene derivatives were the main group of volatiles in the EO from fruits and in the HS from seeds (45.0 and 64.0%, respectively), while oxygenated hydrocarbon derivatives were the main constituents in the HS obtained from fleshy mesocarps (96.5%). The different chemical composition of the headspace obtained from the seeds and mesocarps of M. argun can be correlated with the different roles that the different constituents play in the prevention of dehydration of the fruits in the desert region from where the plant was collected.     

Determination of oil contents from eight varieties of olea europaea (Olive) grown in Pakistan

Abstract

The olive (Olea europaea L.) is a worldwide famous tree crop having valuable commercial role due to nutritional as well as therapeutic benefits obtained from its edible oil. Eight varieties of Olea europaea L. fruits were obtained from three Agricultural research institutes located in different areas of Pakistan including Quetta, Lorallia and Zhob to extract and determine their oil contents by conventional method as solvent extraction (soxhlet apparatus). Statistical analysis showed significant (p?=?0.002) difference in oil composition of collected plants. Highest amount (percentage) of oil was obtained from Gemlik variety (65%) from Lorallia and lowest oil content from Dolece-agogia variety (17.5%) collected from Quetta. Further research is under consideration to rule out best suitable factors including some soil and environmental factors to obtained more potential cultivars of Olea europaea in Pakistan.     

IR spectroscopy of wood and its main components. XVIII. IR spectra of preparations of lignosulfonic acids from the wood of coniferous and broad-leaved species

General features characterizing the IR spectra of lignosulfonic acids obtained from the wood of coniferous and broad-leaved species have been established the use of which together with quantitative spectral and chemical characteristics of preparations of lignosulfonic acids from spruce- and birchwoods will permit, in spectro-chemical investigations, the characteristics of analogous preparations obtained from the wood of coniferous and broad-leaved species to be given.     

Synthesis of 2-propyloxazole and 2-propyloxazole-4-carboxylic acid derivatives

2-Propyloxazole (VI) was obtained in a number of steps starting from butyronit rile. The hydrazide and amide were obtained from ethyl 2-propyloxazole-4-carboxylate; the amide was converted to the nitrile, from which the thioamide and amidoxime were obtained by the usual method. Attempts to convert VI to 2-propylisonicotinic acid or its nitrile by the reaction of VI with acrylic acid or acrylonitrile did not give positive results.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 7–9, January, 1972.     

平面单测点法评价湿度和温度对药物稳定性的影响

利用均匀设计分散原理, 确定药物的湿度温度平面, 采用单测点法获得药物相关的降解动力学参数. 阿司匹林稳定性加速试验结果表明, 平面单测点法与恒温恒湿法和程序变温变湿法得到的降解动力学参数基本一致. 在药物降解程度及试验的湿度差和温度差相同的条件下, 平面单测点法结果的准确度和精密度均明显优于程序变温变湿法, 且装置简单. 与经典恒温恒湿法相比, 平面单测点法的误差较大, 但试验工作量减少.     

Reaction of 4-Methylene-1,3-dioxolan-2-ones with Hydrazines

The structure of the products of the reaction of 4-methylene-1,3-dioxolan-2-ones with hydrazines is a function of the structure of the starting hydrazine. 1,3,4-Oxadiazin-2-one derivatives are obtained from hydrazine hydrate. 3-Arylaminooxazolidin-2-ones are obtained from monoarylhydrazines, while mixtures of these derivatives are obtained from aliphatic monoalkylhydrazines.     

Synthesis of mono-cationic and dicationic analogs of hoechst 33258

The synthesis of fourteen mono-cationic and six dicationic analogs of Hoechst 33258 is described. The monocationic benzimiazoles 7a-7g and the dicationic benzimidazoles 9a-9c are obtained in five steps starting from 4-acetamidobenzonitrile. The monocationic bis-benzimiazoles 12a-12g are synthesized in four steps starting from 4-amino-3-nitrobenzonitrile. The dicationic bis-benzimiazoles 17a-17c are obtained in six steps starting from 4-amino-3-nitrobenzonitrile.     

Effect of dose of xylanase on bleachability of sugarcane bagasse ethanol/water pulps

Pulps obtained from the ethanol/water cooking of sugarcane bagasse were bleached with the xylanase enzyme obtained from the fungus Thermomyces lanuginosus IOC-4145 and with the commercial enzyme Cartazyme HS from Sandoz. By changing the enzyme dose from 4.3 to 36 IU/g of pulp, kappa number and viscosity were maintained when the xylanase from T. lanuginosus was used. On the other hand, by using Cartazyme HS, kappa number decreased by 17%, reaching 35.5. This pulp was further extracted with NaOH without a decrease in viscosity (10 cP), and pulp with a kappa number of 13 was obtained. Xylanases had no significant effect on the ethanol/water pulps.     

Preparation of powder cellulose

Powder cellulose was obtained according to the scheme of hydrolysis-bleaching from the wood technical (unbleached) sulfate cellulose. In the first step, from the crude cellulose lignocellulose material was obtained, which in the second step was subjected to delignification by treating with hydrogen peroxide and chlorine dioxide.     

Sorption of methanol/MTBE and diffusion of methanol in 6FDA–ODA polyimide

This article discusses the diffusion and solubility behavior of methanol/methyl tert‐butyl ether (MTBE) in glassy 6FDA–ODA polyimide prepared from hexafluoroisopropylidene 2,2‐bis(phthalic anhydride) (6FDA) and oxydianiline (ODA). The diffusion coefficients and sorption isotherm of methanol vapor in 6FDA–ODA polyimide at various pressures and film thicknesses were obtained with a McBain‐type vapor sorption apparatus. Methanol/MTBE mixed‐liquid sorption isotherms were obtained by head‐space chromatography and compared with a pure methanol sorption isotherm obtained with a quartz spring balance. Methanol sorption isotherms obtained with the two methods were almost identical. Both methanol sorption isotherms obeyed the dual‐mode model at a lower activity, which is typical for glassy polymer behavior. The MTBE was readily sorbed into the polymer in the presence of methanol, but the MTBE sorption isotherm exhibited a highly nonideal behavior. The MTBE sorption levels were a strong function of the methanol sorption level. Methanol diffusion in the polymer was analyzed in terms of the partial immobilization model with model parameters obtained from average diffusion coefficients and the dual‐mode sorption parameters. Simple average diffusion coefficients were obtained from sorption kinetics experiments, whereas the dual‐mode sorption parameters were obtained from equilibrium methanol sorption experiments. An analysis of the mobility and solubility data for methanol indicated that methanol tends to form clusters at higher sorption levels. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2254–2267, 2000