VOLUME 20, NO2, JUN 1998

The conversion of alkylphenyl ethers to alkylated benzenes

Various alkyl (substituted)phenyl ethers have been prepared and then these compounds were treated with zinc powder at about 350 degrees C. As a result alkylated substituted benzenes were obtained.read more

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ERKAN YANARATES ,YILMAZ YILDIRIR ,SEDAT COSGUN ,

Study of cotton effect of L-mandelic acid and its derivatives

Cotton effect of L-mandelic add and its chiral derivatives L-ethylmandelate, L-ethyl chloro phenyl acetate and L-chloro phenyl acetyl chloride has been studied from their CD spectra, which shows their absolute configurations. The observed variation in the CD data has been explained as the effect of the electronic factors of substituents on the optical activity of the chiral molecules.read more

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M HAMMAD KHAN ,TASNEEM ZAHRA RIZVI ,M AKRAM KASHMIRI ,

Flow behaviour of concentrated solutions of poly(methyl methacrylate)

The flow behaviour of unfractionated poly(methyl methacrylate) (PMMA) (M-w = 1.27 x 10(5)) in acetone and acetonitrite was studied in concentration range 2-12 gm/dl with 2 gm/dl increment, in the temperature range 10-30 degrees C for acetone and 30-45 degrees C for acetonitrile with 5 degrees C interval. Roto-viscometer with NV sensor system was used for this purpose. From the data it was observed that three distinct regions could be seen in shear viscosity (eta) as the shear rate (gamma) was varied from 2.7-245 s(-1). The viscosity was almost constant in the low and high shear rate regions, while in the sheer rate region 12-244 s(-1) viscosity showed a decrease. The zero shear viscosities were calculated by taking the average of first three readings. From this data the critical concentration (C-.), where entanglement occurred, was shown to be above 6 gm/dl.read more

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SAEED ANWAR ,KHALID MAHMOOD ,BAKHTIAR MOHAMMAD ,AKHTAR SAEED ,

Effect of phosphate enrichment on the metal adsorption properties of hydrous iron oxide

Effect of phosphate enrichment on the metal adsorption properties of hydrous iron oxide was investigated in aqueous electrolyte solutions. Phosphate enrichment caused progressive decrease in the point of zero charge of the oxide which resulted an increase in its adsorption capacity towards Cu(II), Cd(II), and Ni(II) ions. Mechanism of adsorption of these metal ions was monitored from the alkalimetric titrations and adsorption measurements performed simultaneously in the same medium Both sets of experiments indicated that the affinity of these metals for the phosphate-free and phosphate-enriched surfaces followed the order, i.e. Cu(II) > Cd(II) > Ni(II).read more

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S F ARSHA ,KAUSAR IQBAL ,KHALIDA AKHTAR ,IKRAM UL HAQ ,

Nitrate and nitrite contamination of sub-surface water in some areas of North West Frontier Province (NWFP) Pakistan

Over the past few years, nitrate and nitrite contamination of sub-surface water samples from Peshawar, Charsadda, Mardan and Nowshera districts of NWFP has been studied. In all the areas under study, nitrate concentration of sub-surface water was found to be below WHO approved limit of 45 mg/L. Whereas, Peshawar city area after 1987 showed a decreasing level of nitrate contamination of sub-surface water, it appeared to be on the increase in water samples from the outskirts of Peshawar along Pehsawar-Charsadda road. No uniform increasing or decreasing patterns of nitrate contamination were observed for water samples from cantonment, University and Hayatabad, areas of Mardan, Charsadda and Nowshera under study. The nitrate contamination of sub-surface water appeared to be due to both the agricultural activities as well as human and animal wastes. A few sub-surface water samples from Peshawar city, Mardan and Nowshera areas indicated high concentration of nitrite, which is alarming in view of the earlier reports showing absence of nitrite in water samples from these areas. However, since 1993, nitrite presence has not been detected in sub-surface water samples from all the areas under present investigation.read more

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IMDAD ULLAH ,MUMTAZ KHAN ,MAHMOOD A KHWAJA ,

Chemical investigation of the air quality in work place environment of selected industries

Samples of air from the work place environments of selected industries were collected. These samples were analysed for carbon monoxide (CO), sulphur dioxide (SO2) and heavy metals like, Lead(Pb), Copper(Cu), Chromium (Cr), Cadmium (Cd), Zinc (Zn) and Iron (Fe), by standard methods. The results are presented and discussed. The level of these elements varied in the range of 0.79-1.43, 0.07-0.5, 0.22-130, 0.001, 3.7-25, 93.60 and 24.6-59 mu g/m(3) for Pb, Cr, Cu, Cd, Zn and Fe respectively in the air samples of various industries investigated.read more

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HAIDER SHAH ,M RASUL JAN ,MOEEN KHAN ,

Metal complexes of a Schiff base formed by the condensation of S-benzyl dithiocarbazate with furil

New nickedl(II), cobalt(Il), copper(II) and cadmium(II) complexes of a Schiff base ligand formed by condensation of furil with S-benzyldithiocarbazate [HFBT]. These have been synthesised and characterized by element analysis, and spectral [IR, UV-vis, H-1-NMR and C-13-NMR] measurements. The spectral data show that the ligand behaves in neutral bidentate or mononegative bidentate manner.read more

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MAHMOUD A S MONSHI ,

Determination of sedimentation rates of cobalt II insoluble compounds and absorption coefficients of the sedimenting particles using gamma radiation

Studies on the sedimentation rates of cobalt II insoluble compounds show that the chromate and sulphide have higher sedimentation rates of 4.38 cm(3) min(-1) and 5.90 cm(3) min(-1) respectively while the cyanide had the lowest sedimentation rate of 0.230 cm(3) min(-1). The cyanide, chromate and sulphide show first order sedimntations while the carbonate and hydroxide show half order sedimentations. The sedimentation constant increases with increase in sedimentation tate. The carbonate had the lowest mass absorption coefficient of 0.014 cm(2) g(-1) while the chromate had the highest mass absorption coefficient of 0.071 cm(2) g(-1) and absorption coefficient has a linear dependence on the sedimentation rate.read more

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I O ESSEIN ,SAMUEL D EKPE ,

Metal contamination in ground water of Korangi Industrial Area, Karachi

The levels of trace metals and major chemical constituents in 28 ground water samples of Korangi Industrial Area (KIA) and its adjoining areas were determined to assess the impact of uncontrolled disposal of industrial waste water on the quality of water. The concentration of metals viz. Zn, Mn, Fe, Cu, Pb, Cd, Ct, Co and Ni, were found to be excessive higher than the WHO recommended limits. The significantly higher concentration of major chemical constituents and trace metals in KIA water samples than the corresponding concentrations in the adjoining areas samples clearly indicated that the contamination in ground water of KIA was primarily due to percolation of industrial waste water into the acquifer of the area. The positive and high correlation co-efficient values (r) showed strong correlation among the metals and also suggested high and consistent trace metals concentration in the ground water under investigation.read more

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FAROOQ AHMED KHAN ,SITWAT NAEEM ,ISHRAT ULLAH SIDDIQUI ,S NAEEM MAHMOOD ,

Glucuronides of Diploclisia glaucescens

Spectroscopic evidence is presented for the structures of four new triterpenoid saponins 3-O-beta-D-glucuronopyranosylsejanic acid, 3-O-beta-D-glucuronopyrancsylphytolaccageni acid 3-O-beta-D-glucuronopyranosyl-28-O-beta-D-glucopyranosylserjanic acid and 3-O-beta-D-glucuronopyranosyl-28-O-beta-D-glucopyranosylphytolaccagenic acid isolated from Diploclisia glaucescens. One saponin has shown acceptable molluscicidal activity.read more

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J K MACLEOD ,G P WANNIGAMA ,U L B JAYASINGHE ,