VOLUME 24, NO1, MAR 2002

An Estimation of Enthalpy of Amorphous Alloys using Differential Thermal Analysis (DTA) Technique

The enthalpy energies are calculated   by using   exothermic peaks of differential (thermal analysis (DTA) en Cobalt-Boron liquid quenched amorphous alloys. The endothermic peaks are not distinctly recorded.   The  diffusional  recovery  processes  in Co-B  LQA   alloys occur  at  about  693K  and  temperatures less    than 800K;  which  suggests  that the polymorphic transformation of   cobalt   is   responsible   for   diverse   diffusion  recovery    processes   such  as intestinal and   vacancy formations,   Cottrell-Lomer locks,  point  defects  due   to  free  covalent bonds (dangling   bonds), edge/edge    and  screw/screw   annihilations through forced  climb  due  to   thermal  stresses  and  indeed   due   to   non-operative  slip   systems  of  cobalt   (both  basal   and pyramidal slips).   Structural changes  in  Co-B  LQA alloys   occur  at above  800K mainly  due  to operative slip systems  in  Cobalt (both  basal  and pyramidal)  which  cross   each other (cross-slip) due  to  thermal  stresses  and annealing.  The cross-slip in  o p.h.  metals (cobalt) particularly  allow temperatures is indeed difficult.read more

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A HUSSIAN ,S M RAZA ,S M M R NAQVI ,S D H RIZVI ,S RIZVI ,F REHMAN ,

Potentiometric Determination of Dissociation Constants and Gibb's Free Energies of a-Hydroxyquinoline (oxine) and 2-Methylquinoline Using Aqueous and Mixed Organic-water Solvent Systems

The dissociation constants (pKa4) and thermodynamic parameters Gibb's free energies (DG) have been determined by a potentiometric pH titration of 8-hydroxyquinoline (oxine) in water at 25 to 50°C and for 24-methylquinoline in water and in aqueous binary mixtures of dioxane, ethanol (EIOH) and methanol (MeOH)at 25°C ± 0.l°C. The first and second dissociates constants of oxine have been analyzed and discussed with (DG)   thermodynamic parameters. The pK values and thermodynamic parameters of 2. methylquinoline have also been computed and discussed in term of solute-solvent interactions. The curves found in both the compounds are a part of a parabola and these follow quadratic equations. The results are correlated with dielectric contants of medium and discussed in term of solvent characteristics, solvent basicity and stabilization of conjugate acid for base by hydrogen bonding interaction in hypo-organic solvent media.read more

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A W K KHANZADA ,H A B INDHAR ,

Stilbene Based Direct Dyes-effect of Fixing Agents on the Fastness and Colour Properties

The dyed cotton fabrics after dyeing are usually treated with different auxiliaries to impart desirable properties according to their commercial uses in industries. An attempt has been made to improve the wash fastness and colour properties of eleven non-benzidine direct dyes   based on 4,4'-diaminostilbene-2,2'-disulphonic acid. The effectiveness of three fixing agents   used was   determined by comparing the properties of treated and untreated dyed substrate. All  the three fixing agents showed beneficial effects on these properties as assessed by ISO  CO 5  wash fastness and on the colour properties like tristimulus values, CIE L*a*b* co-ordinates,  chromaticity co-ordinates and  Munsell  values.  Use   of these fixing agents improved the wash fastness of these dyes on cotton as well as the brightness and strength of the colour in a similar pattern.read more

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C M ASHRAF ,S WAHEED ,

Determination of Hg(II) as A Pollutant in Karachi Coastal Waters by Cold Vapor Atomic Absorption Spectroscopy

Nowadays, environmental monitoring has great importance and mercury is well known for its toxicity. Mercury (which   is at  trace level)  is analyzed by    cold vapor atomic absorption spectroscopy with amendments that   are appropriate to the present laboratory need. The   results are consistent with previous analysis, through   other methods. Two areas namely Ibrahim    Hyderi  and  Fisheries  were  found  to  have  mercury  levels  around  0.193  µg/L   and 0.110µg/L, respectively.     Whereas other areas have  mercury  levels  similar  to  other places reported earlier.read more

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J SHAZLI ,S RAJABALI ,S MOHIUDDIN ,I I NAQVI ,I ZEHRA ,

Kinetic Study of the Reduction of Ferric-1, l0-orthophenanthroline with Uranium (IV) EDTA

The kinetics and mechanism of the reduction of ferric 1,10 arthophenanthroline by Uranium (IV) ethylenediammine tetra acetate  was investigated in aqueous hydrochloric acid   at 25°C, ionic strength 0.01 mol dm-3 and pH 3.5. Rate law for the formation of Fe (II) opt was established through spectrophotomeiric  measuresed   at constant and varying pH by isolation method. At pH of 3.5 and temperature of 25°C, the order of reaction    was found to be second having the value of 221    M-1 mind   and   rate law is suggested    to be   d/dt [Fe(opt)3 ]+2 = K1 [U(IV) EDTA H+ } [Fe(opt)3 ]+3. Differed thermodynamic functions for the reaction were Ea= 3.37 KJ mol-1, DG = -42     KJ mol-1, DH-2 KJ mol-1and DS =148 J K4 mol-1. At different pH values the rate law  was observed as rate = Kk1[H+]  [ U(IV) EDTA ] [Fe(opt)3 ]+2, where K is equilibrium constant for the reaction [U(IV) EDTA] + [H+] - [ U(IV) EDTA H+ ] and k1 is the specific rate   constant for  the reaction  [U(IV)EDTA H]+   + [Fe(opt)3]3+® [U(V)EDTA]  + [Fe(opt)3]2+.read more

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M QADRI ,M A FARRUKH ,I I NAQVI ,

Infrared Spectral Studies of Propanoic Acid in Various Solvents

Effects of various solvents on the infrared spectra of propanoic acid   were studied. Fundamental vibrations  v(0-H), &(0-H)   and   v  (C-O)    were  investigated  with  respect  to solvent change.    The  v  (C=O)   vibration  was  also  studied   in  a binary   mixture  of  carbon tetrachloride and acetonitrile. Results were interpreted in terms of solute-solvent interactions.read more

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N RAUF ,M IKRAM ,M A RAUF ,

Synthesis of Mixed Aliphatic, Aromatic and Halogen Substituted Tin Compounds and Their Analysis for Conformation

Organotin compounds     are very useful in all walks of life. These compounds have an   advantage  over  other metallic  compounds,  since  the inorganic   tin species  formed   upon degradation  are  non toxic, no environmental pollution. Organotin compounds  were synthesized and analysed. The identity of products were confirmed by classic and modem techniques.read more

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M H Z CHAUDHRY ,R G REES ,

Chiroptical Properties of Some (S)-N,N'-Bis[(1-phenyl-5-alkyl-4,5-dihydro-6¬oxo-l,2,4-triazin-3-yl) ethylidene] propane-l,3-diamine nickel(II)

Model  chiral 3-acetyl4,5-dihydro-1,2,4-triazinones  1a-e   were reacted,     utilizing the template effect, with 1,3-diaminopropane  in the presence of nickel  acetate.   The resulting chiral open chain tetranza-type nickel complexes 2a-c were characterized by elemental analysis and NMR spectral   data.   Their CD spectra in organic solvents revealed the   same features for the masked aliphatic and  aromatic  amino  acid  residues  of the  same L-configuration. The stereochemistry at C-5 is correlated with the signs of the observed CE bands.read more

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R M EL ABADELAH ,M H Z CHAUDHRY ,W VOELTER ,

Separation of Copper I and II Iron II and III in Composite Aqueous Matrix by Compititive Chelation Using Disc Electrophoresis Technique

A  new, simple   and rapid  Disc electrophoresis  method  has been developed   in  our laboratory for  determination of different oxidation states of Iron and  copper singly as well   as  in mixture  form  through  the specially   prepared  glass  tubes   of polacrylamide   gel   using  glycine   buffer  at  pH  4  and  3.5. For quantitative analysis   the intensity of electrophoratically separated colored   bands   of   respective   metal   ions in   the   tubes   were    measured   using   Thin   layer chromatographic scanner CS-910.  Ne developed plates      were scanned   separately in UV,   Vis and   fluorescence    regions   on    pre-determined       wavelengths   simultaneously   integration   and profile mode.   It has  been  observed that,  very sharp  Disc  bands  with particular  colour  of both cations with  different  oxidation  state were  obtained   with approximately ten  micron  thickness. The detection limits has been achieved in the range of mg/µl level.read more

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M A JAKHRANI ,T G KAZI ,M F KHAH ,M H S WATTOO ,G H KAZI ,

Evaluation of Mineral Bottled Water Samples for Different Physical and Chemical Parameters

The quality of drinking water is regulated in most countries under recommendation and legal requirements.      For developing countries regulations   are framed by   World  Healh. Organization (WHO)     since 1984  and  onwards.  Normally ground    water and  surface   water (River, lacks, springs) are used for bottler's choice of water.In the present paper  we have evaluated the pure    water supplied by many factories in bottles with    different  brand  names.   Such  mineral  water   was  analyzed  for  different physical   and chemical  parameters.  The quality of bottled   water   is compared   with  U.S.   Federal  Drug Administration (FDA) guidelines for bottled    water and World Health Organization standards for drinking water.read more

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T G KAZI ,M H S WATTOO ,F ANWAR ,M A JAKHRANI ,