VOLUME 32, NO2, APR 2010

Isomerization of 3,4-Dichloro-1-butene into 1,4-Dichloro-2-butene by Heterogeneous Catalysis

The isomerization of 3,4-dichloro-1-butene into 1,4-dichloro-2-butene was investigated by gas-liquid chromatography in the temperature range of 60-90 ºC. Fe2O3/TiO2 was used as a catalyst. Fe2O3/TiO2 solid acid catalyst has been prepared by the support saturation method, tested in the isomerization of 3,4-dichloro-1-butene into 1,4-dichloro-2-butene. This catalyst shows a high activity opposite to pure titania in this reaction. The present investigation focuses on the reactivity of titatia supported ferric oxide with iron contents of 5 wt. % in the isomerization of 3,4-dichloro-1-butene into 1,4-dichloro-2-butene. The activation parameters have been evaluated under optimized conditions, using the Arrhenius and Eyring plots.read more

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NARGES SAMADANI LANGEROODI ,

Phosphorus Adsorption Parameters in Relation to Soil Characteristics

Understanding of soil phosphorus (P) adsorption chemistry is essential for evolving best fertilizer management practices aimed at enhancing fertilizer P use efficiency and environment quality. Soil chemical parameters which govern P adsorption maxima and binding strength in calcareous and non-calcareous soils were determined. Five soils representing three different parent materials i.e. mixed mineralogy alluvium, loess and noncalcareous sandstone were sampled at genetic horizons in each profile. Phosphorus adsorption isotherm was developed for each of the 32 soil samples by equilibration of two g air dry soil with 0 to 4000 mg l-1 (0 to 125 mM) P in 20 ml of 10 mM KCl; and fitted to Langmuir and Freundlich equations. The chemical parameters i.e. pH, CaCO3, total and dissolved organic carbon, exchangeable calcium, dithionite extractable iron (Fed) and aluminum (Ald), oxalate extractable iron (Feo) and aluminum (Alo) and as a test for plant available P extractable with NaHCO3 were determined. The Fruendlich equation, an empirical relation between adsorbed and solution P, fitted the adsorption isotherms better than the Langmuir equation which relates adsorption to solid surface coverage by adsorbate. Adsorption maxima at low affinity sites positively correlated with soil CaCO3 due to precipitation as Ca-P and to extractable iron oxide; and the binding strength of high affinity (k1) sites correlated positively with soil Fed, Alo, Ald, and crystalline iron oxide (Fed-Feo) contents. The Freundlich parameter bf, adsorption exponent which signifies sorption intensity also positively correlated with soil Fed, Fecr and Ald contents. Phosphorus adsorption at its low concentration in equilibrium solution seems to be governed by soil iron oxides and precipitation as Ca-P is important only at high P concentration, less frequently achieved in farm fields.read more

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MEHRUINSA MEMON ,AYAZ MEHMOOD ,MOHAMMAD SALEEM AKHTAR ,RIFAT HAYAT ,

Characteristic Study of Assimilable Organic Carbon (AOC) Formation Potential in Drinking Water

  Summary: Characteristic study of assimilable organic carbon formation potential (AOCFP) at different reaction conditions of ozonation using model raw water containing humic substances and natural source drinking water was conducted. At low ozone dosage, assimilable organic carbon (AOC) concentration tended to increase. Maximum AOC concentration was determined when the residual ozone started to be measured. Therefore, ozone dosage required at maximum AOC concentration was found suitable to measure AOCFP in sample water. No significant relationship between dissolved organic carbon and respective ozone dosages was established. Variations in pH conditions found to have great influence on the development of AOC in sample water. Highest AOC concentration was estimated at pH 8 and a significant reduction in AOC concentration was observed as the system moved towards higher basic conditions, i.e., from pH 8 to pH 9. read more

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JI HOON KIM ,DAE SUNG LEE ,TAHIR IMRAN QURESHI ,YOUNG JU KIM ,

A Model for Making Field-Based Nitrogen Recommendations For Winter Wheat in Western Oregon

A model based on early spring soil and tissue analysis was developed and evaluated for predicting the need for additional nitrogen (N) fertilizer on winter wheat. To develop the model, On-farm trials were established over three years 1994-95 in grower’s fields at three different locations across the Willamette Valley of western Oregon. Two field-scale validation trials were run in 1996-97. Rotations were soft white winter wheat following grass seed, sweet corn or a legume. Four treatments, including a check receiving no nitrogen, were used at each site. At the site where wheat followed corn, the predicted optimum N rate was 168 kg N ha-1; however, the 112 kg N ha-1 rate was the optimum rate predicted by the developed model. The 84 kg N ha-1 and 140 kg N ha-1 rates were selected to bracket the recommended rate (± 28 kg N ha-1).Wheat following grass seed had high soil supplied N which depressed the yield even at moderate fertilizer N rates. The model overall accurately assess field-specific optimum fertilizer N status.read more

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MAQSOOD AHMED KHAN ,MOHAMMAD AYAZ KHAN MALGHANI ,DOST MOHAMMAD BALOCH ,EHSANULLAH KAKAR ,

Lightscattering and Viscosities Measurements of Dilute Solutions of Some Schiff Base Polymers

 Summary: Three Schiff base polymers polymethylene-bis(salicylaldehyde)tetramethylethlene-diimine (PMSATen), polymethylene-bis(salicylaldehyde)meso-stillbenediimine(meso-PMSAS) and poly-methylene-bis(2-hydroxyacetophenone)1,2-propylenediimine (PMHAPn) were prepared and  indicated refractive index increments (dn/dc) within 0.223-0.241 at 436 nm and 0.155-0.130 at 546 nm. The data for dn/dc was obtained by extrapolating intercept of plot  ?n/c against concentration  to zero concentration. The values of Hc/τ (τ = turbidity) were plotted against concentration and reciprocal of the intercept at zero concentration gave the molecular weight in the range of 58100-66890.The polymers were examined for reduced, intrinsic, inherent and absolute viscosities. Thermodynamic parameters as energy of activation (?Gv), heat of activation (?Hv) and entropy of activation (?Sv) of viscous flow were calculated at different temperaturesread more

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KHALIDA PARVEEN MAHAR ,MUHAMMAD SALEM KHAN ,MUHAMMAD YAR KHUHAWAR ,SUBHAN ALI MAJIDANO ,ABDUL HAMID CHANNAR ,

Acidic Surface Functional Groups and Mineral Elements in Lakra Coal (Sindh, Pakistan)

Surface acidity of virgin coal (Lakra Sindh, Pakistan) and variously extracted/leached coal samples leached with HNO3, NaOH, and KMnO4, were investigated by aqueous potentiometric titration employing KOH as a titrant. The titration curve of virgin coal showed that its surface might contain carboxylic, carbonyl, phenolic and other weak acidic functional groups such as enols and C-H bond. The titration curves of leached coal samples showed inflections at pH 4-11, being not similar the inflections of carboxylic groups. This inflection might be given by functional groups like CO2, phenolic, enols and C-H. Mineral matter such as Fe, K, Zn, Mn and Ni were determined in the ash of coal by atomic absorption spectrophotometer and was found that Fe (3104 µg/g) in the highest and Ni (36.05 µg/g) in the lowest quantity is present in virgin coal sample.read more

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SAJJAD HAIDER ,MUHAMMAD SHAHKIRULLAH ,MUHAMMAD ISHAQ ,IMTIAZ AHMAD ,KHALID SAEED ,

Effect of Molecular Mass of Polyethylene oxide over its Aggregation Behavior

Samples of polyethylene oxide having different molecular mass (35, 12, 6 Kg/mol) are investigated with reference to characteristic concentration (CC), critical aggregation concentration (CAC) and hydrodynamic radius (RH), using surface tension, light scattering, viscosity and conductance measurement. It has been concluded that CC and CAC decrease with molecular mass of polymer. The intrinsic viscosity, RH and molecular mass relationship have also been established. read more

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GULREZ FATIMA DURRANI ,ABDUR RAUF ,MUSA KALEEM BALOCH ,

2,7-Dichlorofluorescein: a Suitable Complexing Agent for the Spectrophotometric Determination of Ofloxacin in Pure and Pharmaceutical Dosage Forms

Ofloxacin is a broad spectrum antibiotic effective against many Gram positive and Gram negative bacteria as well as for some key anaerobes. Ofloxacin was reacted with 2,7-dichloroflourescein in an acidified medium at room temperature to give a crimson-red complex which was measured at 430 to 460 nm (working wavelength 430 nm), thus providing a basis for a new spectrophotometeric  method of analysis for ofloxacin in pharmaceutical dosage forms. The complex in solution form obeyed the Beer’s Law between 0.02-0.25 mg/mL. The limit for detection was 0.02 mg/mL. The relative standard deviation was found to be 0.67 %. Similarly the molar absorptivity for complex was calculated to be 0.01×104 dm3mole-1cm-1. This method was found to be useful for the estimation of ofloxacin in pure as well as in pharmaceutical formulations. This method was easy to execute at laboratory level and required non cumbersome methodology, with a relatively high precision and accuracy.read more

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SYED HASNAIN ALI ,AZIZ UR REHMAN ,MUHAMMAD JAHANGIR ,SABAHAT ZAHRA SIDDIQUI ,MUHAMMAD ASHFAQ ,MUHAMMAD ZAHID QURESHI ,MUHAMMAD ATHAR ABBASI ,VIQAR UDDIN AHMAD ,

HPLC Determination of Putrescine and Cadaverine in Serum of Cancer Patients Using Acetylacetone as Derivatizing Reagent

Liquid chromatographic procedure has been developed for the determination of putrescine (Put) and cadaverine (Cad) after derivatization with acetylacetone in aqueous-methanolic solution at pH 8.2. The derivatives were eluted and separated from µ Bondapak C-18, 10 um (3.9´300 mm id) with water:methanol:acetonitrile (73:22:05 v/v/v) with a flow rate 1.2 ml/min. The UV detection was at 310 nm. Linear calibration curves were obtained 25-200 ng Put and Cad / injection (10 µl). The method was used for determination of Put and Cad in the blood serum of cancer patients before, during and after radiotherapy and were in the range of Put 0.622-3.674 ± S.D 0.017-0.153 mg/mL and Cad 0.229-1.854 ± S.D 0.002-0.046 mg/mL. The limits of detection were observed 2.5 ng Put and Cad / injection (10 µL). the recoveries of Put and Cad from serum were calculated to 94.2-97.3 %. The concentration of Put and Cad observed were lower after radiotherapy.read more

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MUHAMMAD USMAN MEMON ,ROSHAN ALI GILAL ,MUHAMMAD YAR KHUHAWAR ,ABDUL HAKEEM MEMON ,FAQEER MAHBOOB ALI RIND ,

Drug Release Kinetics and Stability Studies of Tablets of Tramadol HCl Microspheres

The objectives of study were the development of new formulations of Tramadol HCl (TmH) microspheres and their evaluation primarily for kinetics and stability. Microspheres of different polymer concentration M1 (1:1), M2 (1:2) and M3 (1:3) were developed and compressed into tablets i.e., T1, T2 and T3, respectively. Zero order, First order, Higuchi, Hixson-Crowell and Korsmeyer-Peppas kinetic models were applied to assess the mechanism and pattern of drug release. Higuchi model was found to be the best among all models. The chemical and physical stability of TmH formulation was studied using FTIR, Thermal analysis, X-ray diffraction and dissolution tests. In-vitro analysis showed that tablets of ratio T2 released the drug over 12hrs and the release profile was comparable with that of reference tablet, Tramal® SR. The effect of different storage temperatures on the physicochemical stability of T2 was insignificant (p > 0.05).read more

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MAHMOOD AHMED ,MUHAMMAD ASADULLAH ,NAVEED AKHTAR ,MUHAMMAD NAEEM AAMIR ,GHULAM MURTAZA ,