VOLUME 21, NO4, DEC 1999

Conformational analysis of polyacrylamide

In this paper the dependence of the Electrostatic Potential (ESP) fitted charges, that play an important role in Molecular Mechanics (MM) calculation on the conformations, is studied It is concluded that in order to accurately calculate the energy of one conformation, the (ESP) charges corresponding to the studied conformation must be used Systematic search method is used to search the conformers of CH3-CH(CONH2)CH2-CH2-CONH2 which is the model compound of Polyacrylamide and 16 stable conformers are found. The most stable conformer is also obtained.read more

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LI ZERONG ,MUHAMMAD ASHRAF KHAN ,ANMIN TIAN ,

Dosimetric characteristics of FWT-63-02 radiochromic film for quality assurance in radiation processing industry

For a commercially available radiochromic film (FWT63-02), response functions were determined at the wavelength of maximum absorbance (600 nm) and at several other wavelengths, such as 550, 625, 640 and 650 nm At 600 nm the dosimeter was found to have a linear response up to 5 kGy. At longer wavelengths (625, 640 and 650 nm), the film can be useful even up to 25 kGy. Post-irradiation stability at different storage temperatures (-10. 7, 25, 40 and 60 degreesC) for dosimeters irradiated to 2 or 4 kGy was also determined. The response at lower temperature (-10, 7 degreesC) was stable up to 35 days. At 40 and 60 degreesC the dosimeter, apart from some initial increase in the response for the first 24 hours showed nearly stable response up to 40 days. Possible use of these radiochromic film dosimeters for quality assurance in radiation processing using gamma rays has been discussed.read more

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HASAN M KHAN ,MIAN S WAHID ,

Solvent dependent N-14 chemical shifts in quinoline

N-14 chemical shifts of neat quinoline and 90% quinoline in different solvents have been measured. DMSO-d(6) was used as an internal locking agent NH4NO3 wits used as an external standard. The N-14 chemical shift of neat quinoline with respect to NO3. ion is -71.75 ppm previously reported N-14 chemical shifts by this group in pure quinoline was -72 +/- 2 ppm in external lock mode. The internal lock result are more accurate. The chemical shifts of 90% quinoline in carbon tetrachloride, chloroform and dioxane are nearly the same i.e -71.57, -73.61 and -70.14 ppm respectively. The N-14- chemical shifts of 90% quinoline in water and methanol are relatively low i.e. -135.87 and -109.96 ppm respectively. This is due to hydrogen-bonding of nitrogen with water and methanol. In DMSO and acetone the N-14 chemical shifts are - 63.41 and -62.78 ppm respectively. This may be due to complex formation of these compounds with quinoline. In all such cases N-14 studies has been done at a frequency of 6.43 MHz using JEOL FX 90Q FT NMR. To avoid the base line rolling due to low frequency and acoustic ringing a delay time of 400 mus has been used.read more

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A W K KHANZADA ,SHAMA PATHAN ,

Physico-chemical characteristics of sub surface water of Haripur area-Hazara (NWFP)

The level of pollution in water samples from Haripur area of Hazara were investigated by measuring the quality of subsurface water collected from 13 localities of the area 18 physical and chemical parameters were measured and the values were compared against standards for ascertaining the suitability of water for human consumption. Parameters values for most of the samples were found to be within the permissible limits but some values were very close to the maximum permissible limits and therefore, appropriate measures should be undertaken to control further contamination of water, otherwise, the water would no longer be safe for the inhabitants of the area in the near future.read more

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MUMTAZ KHAN ,MAHMOOD A KHWAJA ,

Acid leaching studies on Sphalerite Ore of Kohistan Hazara for the recovery and separation of Lead and Zinc

Investigations were carried out for the recovery and separation of Lead and Zinc from the Sphalerite Ore of Kohistan-Hazara by acid leaching. Parameters like acid concentration, temperature and time of leaching were optimized for the maximum recovery of Lead and Zinc from the Ore. It was found that a recovery of 90% of Zinc and 70% of Lead could be obtained if the observed optimum conditions for the parameters studied are followed:read more

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A RAHMAN KHAN ,MUMTAZ KHAN ,KAMIN KHAN ,M RIAZ ,M AKIF ,

Effects of various solvents on the infrared spectra of benzyl alcohol

Effects of various solvents on the infrared spectra of benzyl alcohol were studied. Fundamental vibrations v(O-H), delta (O-H) and v(C-O) were investigated with respect to solvent change. The v(O-H) mode was also investigated in a binary mixture of carbon tetrachloride and acetonitrile. Results were interpreted in terms of solvent-solute interactions.read more

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S SHAHEEN ,M A RAUF ,M IKRAM ,M H BHATTI ,

Evaluation of metal contents in Phulleli canal and Hyderabad city sewage by flame atomic absorption spectrophotometer

Samples from Phulleli canal and sewage water being added to this canal while passing through Hyderabad city was monitored for metal contents using flame atomic absorption spectrophotometer (FAAS). Twelve sampling stations were selected 7 from Phulleli canal and 5 from sewage water. Samples were collected at the interval of 6-8 weeks during 1993-95. Sodium(I), potassium(I), calcium(II) and magnesium(II) were determined after appropriate dilution and their average amounts were within the range of 5.8 - 173.0 mug/L in Phulleli canal and 43 - 527 mug/L in Hyderabad sewage, whereas copper(LI), cobalt(II), cadmium(II), iron(II), manganese(II), nickel(Il), lead(II) and zinc(II) were determined by complexation with ammonium pyrrolidine dithiocarbmate (APDC) and 8-hydroxyquinoline (oxine) followed by extraction in methyl isobutyl ketone (MIBK). Alter back extraction, metal contents were determined in aqueous phase. Their values varied within 4-130 mug/L and 6.5 - 380 mug/L, expect iron whose values varied upto 930 - 1360 mug/L and 830 - 2670 mug/L in Phulleli canal and sewage water respectively. Variation in metal contents with the water discharge in the Phulleli canal and sewage water added was determined to evaluate the distribution of metal contents in Phulleli canal.read more

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I A ANSARI ,M Y KHUHAWAR ,V K DEWANI ,

Synthesis and characterization of silver(II) oxide

Silver(II) oxide (AgO), an active material for batteries, wits synthesized by oxidation of silver(I) nitrate in alkaline medium and was characterized using various physico-chemical techniques for trace metal impurities, structure and thermal stabilities and various physical parameters. The results of analytical analyses involving x-ray fluorescence, atomic absorption and emission spectrometries reveal that the synthesized AgO has the purity >98% and contain Na, Fe, Ca, Cu, Mg Zn, Si Al, B etc. as traces. The structural and thermal investigations show that AgO has monoclinic structure and is stable upto 130 degreesC, beyond that AgO decomposes into two stages; the first stage corresponds to the conversion of AgO to Ag2O while the second stage is the indicative of Ag2O to Ag conversion The determined values of densities lie in the order of bulk density < tap density < true density, having surface area 0.307 m(2)/g average particle size 20.73 micron pore volume 0.235 cm(3)/g and porosity 57%.read more

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SUMEERA IKRAM ,ARSHAD MUNIR ,FIAZ AHMAD ,RIAZ QADEER ,

Flow injection analysis (FIA)

Flow injection analysis (FIA) is a simple analytical sample processing technique, based on the injection of a definite volume of liquid sample solution in a continuously flowing unsegmented carrier stream followed by the quantitation of specie of interest It offers many advantages over manual methods of analysis, like: flexibility, simplicity, selectivity, reproducibility, higher sampling rate, rapid start-up and shutdown time and economy. Injection volume, operation timing and dispersion must be carefully controlled to achieve precise results. Consumption of reagents is a serious. problem in certain cases which can be controlled by the introduction of different FIA techniques. Instrumentation of FIA is simple. A simple manifold can be quickly assembled. This technique has numerous areas of applications such as environmental pollution biotechnology, agricultural, pharmaceutical and clinical analysis.read more

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TAHSEEN GHOUS ,

2-benzylpyridine as a chromogenic reagent for the micro determination of molybdenum and its application 40 steel samples

A simple, rapid and interference free spectrophotometric method for the determination of micro amounts of molybdenum (V) is reported The method is based on the quantitative extraction of Mo(V) by 0.05 M 2-benzylpyridine (BPy) solution in benzene from 3 M HCl solution containing 1 M thiocyanate and 0.4 M ascorbic acid The maximum absorption of Mo(V)-SCN-BPY complex in benzene occurs at 470 ma The Beer's law is obeyed in the concentration range 0.2-2 mug/g. The molar absorptivity and Sandell's sensitivity of the benzene extracted complex is 1.76x10(4) M-1 cm(-1) and 5.4x10(-4) mug cm(-2) respectively. The effect of foreign ions has been studied. The method permits the determination of molybdenum in presence of commonly associated elements.read more

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SUHAIL MUNIR ,ASLAM KHAN ,ALI RUSHEED ,