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The rate of oxidation of thiamine ( Vitamin B, ) by Hg(II) ion in basic medium (pH=12.2) has been studied The concentration of [OH']and Hg(II) were kept constant by using 0.20M phosphate buffer and 2.0×10-3M Hg(II). The initial rate of formation of the only product of thiochrome was followed spectrophotometrically at h = 350 nm for the first 2-3 minutes The reaction has been studied in the temperature range of 279 K to 314.4 K. The reaction is pseudo-first order with respect to thiamine .Different kinetics and thermodynamics parameters such as rate costants, activation energy, enthalpy of activation, entropy of activation and Gibbs energy of activation of the reaction were reported. Various concentrations of thiamine were successfully found by measuring there initial rates in different synthetic mixtures containing other foreign species.read more
R H HINA ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 233
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This study was caried out to have a systematic knowledge of the polystyrene absorbance (M.Wt: 100000) with respect to temperature, concentrations and solvent. A wide range of concentration wm selected for these studies and four different solvents i.e.; 1,2-dichloroethane, ethylaccetate carbontetrachoride and cyclohaxane were employed for this work. The absorption spectra of polystyrene were measured in these four solvents at different temperatures of 10' C, 20° C, 30° C, 40' C, 50° C and 60° C. The effect of concentration, temperature and solvent was determined.read more
Y IQBAL ,S A KHAN ,W KHAN ,M S SHAH ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 237
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A coal sample obtained from Khushab District northern Punjab was characterized for various parameters of coal analysis. It we found from the ultimate and proximate analysis that fmad carbon is a lightly above 40%, which shows that this coal has not reached its maturity and can be ranked between peat and lignite. It was also found that it contain about 2.98% total sulfur, which is an indication that it can be used for metallurgical purposes. The coal has been desulfurized with KOH, NaOH and HNO3 and the sulfur percentage has decreased to 0.001%, 0.01% and 0.006% respectively with these leachants. Calorific value of virgin coal (untreated sample) has been found to be 6195 calories/g but has increased to 10448 calories/g after particularly being leached with (KOH).The coal was also leached with hydrochloric acid and nitric acid to determine the Icachability of these two acids for mineral elements such a copper (Cu), iron (Fe), calcium (Cs), magnesium (Mg), nickel (Ni), mangnesium (Mn), chromium (Cr) and cadmium (Cd). It we found that a very reasonable amount of these minerals could be extracted with these leachants.read more
M ISHAQ ,I AHMAD ,N TAJ ,A BAHADER ,M SHAKIRULLAH ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 240
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Poly 2-vinylpyridine and its homogeneous composites wing different alkali metal salts were synthesized and charaterized by molecular weight determination, infrared spectroscopy, scanning electron micrography and thermogravimetry. Pyrolysis studies by TG, DTG and DTA under ambient condition of static air or argon suggest decomposition of the polymer and composites in more than one step. Kinetic parameters i.e., order of reaction, rate of thermal decomposition of reaction and energy of activation were evaluated from TG isotherm using Horowitz and Redfarn methods. It was found that the pair of composites having the same anions follows the same thermal and kinetic stability order.read more
S ALI ,U RAFIQUE ,M MAZHAR ,M M BHATTI ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 245
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The kinetics of reduction of tris(1,10erthophenantiroline)iron(III) ion by two different reductants hexacyanoferrate(II) ion and bis(s-cyclopentadienyl)iron(II) has been spectrophotometrically investigated in studies median. Measurements were recorded under pseudo-first order condition. The rate of electron transfer between tris(1,10-orthophenan- throline)iron(III) and each reductants was measured. The rate laws are suggested to be, rate = k1 [Fe(C5N5)2] [Fe(o-phen)3]3+ /1 + K[H+] and rate = k [Fe(C5H5)2] [Fe(o-phen)3]3+ for the reduction of tris(1,10-orthophenanthroline)iron(III) ion with hexacyano-ferrate(II) ion and bis(scyclopentadienyl)iron(II) respectively, showing first order with respect to each of the reactants in the both cases. It was found that the rate of reaction with hexacyanoferrate(II) is faster than that of bis(p-syclopentadienyl)iron(II) having the second order rate constant values of 8.33 x 107M-1s-1 and 5 x 106 M-1s-1 respectively.read more
I I NAQVI ,M A FARRUKH ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 252
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The comparative study was done of different wheat varieties in their capacity to accumulate different thirteen cassentials and trace elements grown en same agricultural plot Six samples for each (Zardana, Azri-96 and Daman-98) as representative samples, grown on same plot of agricultural research institute sariab, Quetta. The soil samples of same agricultural plot was also analysed for same elements.Standard reference samples of same varieties was collected from FSCARD (Federal Seed Certification and Registration Department) . Atomic absorption spectrophotometer was used for the determination of all 13 elements. The characteristics mean of each element for three varieties of representative samples were found to be in the ranges of 586.87-974.69, 3606.81- 3697.44, 189.71-269.69, 1511.22-1606.5, 19.19-35.13, 31.7246.59, 32.74-44.28, 4.28-5.32, 1.235-1.551, 0.6094.907, N.D, 0.470-0.528 and 0.271-0.296 mg/kg for Na, K, Ca, Mg, Fe, Zn, Mn, Cu, Ni, Pb, Co, Cd and Cr respectively which were compared with certified samples at 95% confidence limit.read more
M A JAKHRANI ,T G KAZI ,G Q SHAR ,S R SAHITO ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 258
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Potentiometeric studies have been carried out on 1:1 ML mononuclear complexes, where Ca (II), Fe (III) and Zn (II) represent the essential metals whereas Pb (II), Cr (III, VI) and Ni (II) are the biotoxic metal ions. The ligands selected are the polyamino carboxylic acida(PAC)such as EDTA, DTPA and CDTA. pH titrations were performed in aqueous solutions at an ionic strength of 0.l M and temperature 30°C. Formation of above mentioned metal-PAC complexes were studied and compared. DTPA was found comparatively a strong acid among the three PAC acids and suitable for complexation especially at the pH below 2.5 contrarily to CDT A and EDTA.read more
S GULZAR ,Z T MAQSOOD ,N FATIMA ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 262
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The determination of the total elemental contents using wet acid digestion method by nitric acid and hydrogen peroxide for dissolution of seven heavy metals (Cd, Co, Cr, Ni, Pb,Cu and Mn) in the wheat flour of certi6cd and representative samples of eight wheat varieties of the Sindh, Pakistan, by atomic absorption spectrometry. The experimental study was conducted using six samples for each of eight wheat varieties of FSC&RD standard reference materials and representative samples which was collected from four agricultural research Institutes. The characteristics mean of each element for each variety of representative samples found to be in the range of 0.383-0.73, 0.50-1.82, 0.2014.289, 0.777-1.067, 0.525-0.879, 2.42-4.12, and 23.14 -37.14 in mg/kg for Cd, Co, Cr, Ni, Pb, Cu and Mn respectively, and was compared with certified sample which is at the 95% confidence limit.read more
S R SAHITO ,M A JAKHRANI ,G Q SHAR ,T G KAZI ,M A MEMON ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 265
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A series of new disulphides, methylthia, triazolium salt, benzylthio, ylthio acetamide and ylthio acetic acid derivatives of 2,4-dihydro-4-benzyl-5-(pyridyl)-3H-1,2,4-triazole-3-thione have been synthesized. Their IR, 'H-NMR, MS spectral data and elemental analysis have established structures of new compounds.read more
A MOBINIKHALEDI ,T TOFIGHI ,K H ZAMANI ,R IQBAL ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 269
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The fixed oil of Citrullus colocynthis Schrad seeds (Cucurbitaceae) has been investigated for its physics-chemical characterization and the fatty acid composition. The toxicological and hypoglycemic properties of the oil and various crude extracts of C.colocynthus have also been investigated.read more
M SALEEM ,A MALIK ,N AFZA ,M A KALHORO ,
- 05 May 2011
- Volume Detail: VOLUME 24, NO3, DEC 2002
- Pages: 274
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