VOLUME 16, NO4, DEC 1994

EFFECT OF RARE-EARTH (HO, TB AND DY) LAURATES ON THE THERMAL-DEGRADATION OF POLY (VINYL-CHLORIDE)

Non-oxidative thermal degradation of PVC and the effect of (Ho, Tb and Dy) laurates on it was studied using thermogravimetric technique in the temperature range of 150 to 1000 degrees C. It is observed that these metal laurates effectively reduce the dehydrochlorination of PVC. The synergistic effect of combination of these salts was also studied and discussed. Kinetic parameters such as activation energy, order of reaction and Arrhenius factor have been also calculated by the Coats and Horowitz methods. Results show that above mentioned metal laurates increase the activation energy required for the dehydrochlorination of PVC.read more

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R HUSSIAN ,F MAHMOOD ,

CHARACTERIZATION OF ACTIVATED-CHARCOAL

The structural investigations of a commercial activated charcoal were carried out using different techniques such as X-ray diffraction, thermal analysis, nitrogen adsorption and mercury porosimetry. X-ray diffraction study revealed that the activated charcoal is amorphous in nature and has micro-cystalline structure. The thermogravimetric study of activated charcoal showed that the weight loss occurred in two distinct regions: one endothermic (dehydration) and other exothermic (combustion). The moisture and ash contents were found to be 11% and 10% respectively. The pore size distribution curve and DR analysis of nitrogen adsorption isotherm indicates the microporous nature of the activated charcoal with surface area 1000 m(2)/g, porosity 75.74% and pore volume 1.43 cm(2)/g.read more

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M AFZAL ,R QADEER ,M SALEEM ,J HAIF ,

EFFECT OF COUNTERION CHARGE ON THE VISCOSITY OF DILUTE POLYELECTROLYTE SOLUTIONS

Effect of counter ion charge (cation of the added salt) on the viscosity of dilute aqueous sodium polystyrene sulfonate solutions has been studied. It has been observed that for solutions without added salt the reduced viscosity increases with dilution, reaches to a maximum and then decreases in the limit of infinite dilution. In the presence of added salt the height of the maximum decreases and shifts towards higher polymer concentration in the following order AlCl3 > CaCl2 > NaCl.read more

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M S KHAN ,K AHAD ,N AHMAD ,A SAEED ,

SPECTROSCOPIC STUDIES OF SOME TRIDENTATE SCHIFF-BASES AND THEIR METAL-CHELATES

New tridentate ligands isopropanoylacetone-2-imino-phenol (H(2)PAP), trifluoroisc- propanylacetone-2-iminophenol (H(2)F(2)PAP), acetylmesityl oxide-2-iminophenol (H(2)AMP) and trifluocoacetylmesityloxide-2-iminophenol(H(2)F(2)AMP) have been prepared and characterized by elemental microanalysis, IR, H-1-NMR and mass spectroscopic techniques. Their reactions towards copper(II), nickel(II), cobalt(II), iron(II) and chromium(II) have been studied spectrophotometrically. The reactions with metal ions are rapid with molar absorptivities in the range of 100-8000 1.mole(-1) cm(-1) in visible region.read more

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M B RIND ,M Y KHUHAWAR ,A G BHATTI ,A K TALPUR ,

QUANTITATION OF INTRACELLULAR TRYPTOPHAN AND ITS METABOLITE 5-HYDROXY-INDOLE-3-ACETIC ACID IN UREMIC PATIENTS

High performance liquid chromatographic method with electrochemical detection was used to quantitate levels of tryptophan (Trp) and its metabolite 5-hydroxy-indole-3-acetic acid (5-HIAA) levels in erythrocytes and leucocytes of 41 uremic patients. These patients were treated by maintenance hemodialysis (HD, n = 18) and continuous ambulatory peritoneal dialysis (CAPD, n = 25). The method of analysis is accurate, sensitive and reproducible. The results accumulated in uremic patients are statistically compared with age-matched healthy subjects (n = 21). The results demonstrate the abnormal intracellular distribution of Trp and 5-HIAA in uremic patients.read more

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G A QURSHI ,S M BAIG ,M Y KHUHAWAR ,

KINETICS AND MECHANISM OF FORMATION OF TRISGALLATOIRON(III) COMPLEX FROM MONOGALLATOTETRAAQUO IRON(III) AND BISGALLATO DIAQUO IRON(III) COMPLEXES

Kinetics of formation of 1:3 complexes from 1:1 and 1:2 complexes between Fe(III) and gallic acid (3,4,5-trihydroxybennzoic acid) has been studied. The rates were measured spectrophotometrically by monitoring the rise of absorbance at 500 nm (the wave length of maximum absorbance for the tris complex). The reaction was driven by providing a sudden pH jump to 8.0 along with an excess of ligand. Under these conditions, 1:3 complex would completely predominate. The observed pseudo first order rate constant increased with increasing ligand concentration initially, but leveled off at higher ligand concentration. The rate of formation of 1:3 complex from 1:2 complex was slower than it's formation from 1:1 complex by about an order of magnitude. The mechanistic implications of these rate measurements are discussed.read more

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M S QURESHI ,S A KAZMI ,

FLUOROMETRIC INVESTIGATION OF SELECTED METALS OF ENVIRONMENTAL IMPORTANCE

A new spectrofluorometric method is investigated for me determination of some selected metals of environmental importance. The method is an indirect one and makes use or me fluorescence enhancement of sodium diethyl dithoicarbamate (NaDEDC), a chelating agent. Effect on the fluorescence behaviour of NaDEDC by different metal cations like CU(II), Mn(II), Ni(II), Fe(II), Fe(III), Co(II) and Cd(II) was studied and it is observed char almost ail of these cations enhance the fluorescence of the ligand to various extents. Optimum wavelength and pH were investigated for maximum complexation of these metals with the ligand and limit of detection for the metal cations.read more

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H SHAH ,M A KHAN ,M R JAN ,

BISBENZYLISOQUINOLINE ALKALOIDS FROM EPINETRUM-VILLOSUM (MENISPERMACEAE)

A phytochemical investigation of the stem bark of Epinetrum villosum (Menispermaceae) resulted in the isolation of six bisbenzylisoquinoline alkaloids: cycleanine, cycleanine N-oxide, norcycleanine, cocsoline, cocsuline, and a new alkaloid cocsuline N-oxide.read more

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A RAHMAN ,O N OGBIEDE ,SALMA RAHMAN ,M PARVEZ ,

SYNTHESIS OF PYRANO(4,3-B)PYRAN-4,5-DIONES

3-Acyl-4-hydroxy-6-methyl(or phenyl)-2H-pyran-2-ones (III) have been converted into 2,3,7-trisubstituted-4H,5H-pyrano-(4,3-b)pyran-4,5-dione perchlorates (IV) using acetic anhydride and perchloric acid mixture. The perchlorates (IV) on boiling with aqueous ethanolic solution gave the corresponding pyranopran-4,5-diones (II) in moderate to excellent yields.read more

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M SIDDIQ ,A W KHAN ,P F G PRAILL ,

SYNTHESIS AND REACTIONS OF SOME 6-(3-METHYL-4-CHLOROPHENYL)-4-(5-BARBITURATE),2,3,,4,5-TETRAHYDROGYRIDAZIN-3-ONE

Some new pyridazinone derivatives (3) were synthesized through the addition of barbituric acid to beta-aroylacrylic acid (1) followed by cyclization of the adducts. Reactions of (3) with anisaldehyde, bromine-acetic acid mixture and POCl3 gave the 4,5,6-trisubstituted pyridazinone (4), the 5-bromopyridazinone (5) and the tetrachloro derivative (6), respectively. The latter reacts with hydrazine hydrate to give tetrahydrazino derivative (7). Reaction of (3) with phosphorus pentasulfide in one instance namely at short time and less amount of P2S5 gave the monothio derivative (8), in the second instance at long times and excess P2S5 gave the tetrathioderivative (9). Compound (2,3a) and (6) possess moderate activity against Gram-positive. Compound (2) possesses also moderate activity against Gram-negative and slight activity against fungi.read more

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A RADWAN ,M S ABD ELHALIM ,G H SAYED ,M KHALIL ,