VOLUME 33, NO1, FEB 2011
123
 
Design of a Microemulsion-Based Drug Delivery System for Diclofenac Sodium

NADEEM ABBAS KIZIBASH ,SYED SAKHAWAT SHAH ,DHAIFALLAH ALENIZI ,MOHAMMED FAIZAN NAZAR ,SHUMAILA ASIF ,

A microemulsion-based drug delivery system has been designed for Diclofenac Sodium(DS) comprising Span 60, 1-Propanol, Water, and Lemon Oil. The microemulsion system has beencharacterized by a pseudo-ternary phase diagram using the water titration method. The propertiesand structure of this system have been studied by the use of refractive index, electrical conductivity,viscosity and UV-Visible spectroscopy. The conductivity (σ) and viscosity (kη) measurements haveprovided evidence for percolation behavior with variation in Φ (weight fraction of aqueous phase).This phase transition corresponds to the structural change from water-in-oil to a bicontinuousmicroemulsion system. The percolation threshold (ΦC) obtained from conductivity measurementswas in accordance with that obtained by viscosity measurements. Five microemulsion samples wereselected and the changes in microstructure after incorporation of the drug, Diclofenac Sodium (DS)were examined by centrifugation, conductivity measurements, viscosity measurements andspectroscopic studies. The conductivity measurements showed that DS-loaded samples have higherconductivity values when compared to non-loaded samples. It was also found that DS is interfaciallyactive. In addition, loading of DS had no negative effect on the stability of the system.
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Study of CO Hydrogenation Reaction on Cobalt Titania Catalyst

HOSSEIN ATASHI ,HAMED GHAREHBAGHI ,

CO hydrogenation on the cobalt catalyst with Titania support (Co/TiO2) withoutreduction condition and with a fixed-bed differential cylindrical reactor was kinetically studied.Internal and external mass transfer resistances of the porous catalyst are low and neglected inexperimentations. Models have been developed using Langmuir-Hinshelwood-Hougen-Watson(LHHW) theory based on carbide and enolic mechanisms. Models have compared with experimentaldata according to Levenberg-Marquardt algorithm. The best model (-Rco = kPH2/ (1 + aPco)2 ) isselected because of good agreement with experimental data. Absorption step and hydrogendissociation on surface of the catalyst is considered as a rate determination, simultaneously.Activation energy and enthalpy of the carbon monoxide consumption were obtained 82.3 kj/mol andthe 57.9 kj/mol, respectively.
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Heterogeneous Electron Transfer Studies on the Reduction of Some Pyridinium Cations: Substituents and the Inner-Reorganization Energy

MOHAMMAD ASLAM ,MAHBOOD MOHAMMAD ,

Standard heterogeneous electron transfer rate constant k° for some important pyridinium model compounds: N-methyl-a-picolinium- , N-(2,4-dinitrophenyl)-4-(4’-pyridyl) pyridinium-, N-(phenyl)-4-(4’-pyridyl) pyridinium-, N-(cyanophenyl)-4-(4’-pyridil) pyridinium- and N-(2, 4-dinitrophenyl) pyridinium chlorides as well as 1-1’ dimethyl 4-4’-bipyridinium (methyl viologen), were determined using cyclic voltammetric technique.  Methods of Nicholson and Gileadi were used. k° were computed using various forms of  Marcus equations. It was found that the simple Marcus equation gave much higher values of k°; while the precursor equilibrium-model gave better agreement with the experimental results. In all these cases an adiabatic electron transfer was assumed. It was inferred that the general practice of omitting li, the inner reorganization energy, can not be accepted in the present case: when strong electron withdrawing group nitro-, cyano-, carbomethoxy- etc. are the substituents near the reaction site, li should not be ignored.
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Dispersed Nickel Oxide Films for Electro-oxidation of 1, 4-Butanediol

AAKIFA RAZA ,INAM UL HAQUE ,SHAMAILA SADAF ,

1, 4-Butanediol was oxidized using electro-catalytic properties of composite material of nickel oxide and polyaniline. The formation of composite film of nickel oxide and polyaniline was carried out from aqueous nickel sulphate solution containing aniline using cyclic voltammetry at carbon disc electrode. The fine dispersion of polyaniline within the nickel oxide matrix enhanced the catalytic properties of modified electrode towards the electro-oxidation of 1, 4-butanediol. The results indicated that in 1.0 M sodium hydroxide solution, the anodic peak current increased with theconcentration of 1, 4-butanediol.
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Optimization of Aspergillus niger Nutritional Conditions using Statistical Experimental Methods for Bio-Recovery of Manganese from Pyrolusite

ASIM IQBAL ,RASOOL BAKHSH TAREEN ,SHEREEN GUL ,EJAZ ALI ODHANO ,MUJEEB UR RAHMAN ,MOHAMMAD MASOOM YASINZAI ,

The nutritional requirements for Aspergillus niger PCSIR-06 for bio-recovery of manganese from pyrolusite ore were optimized. Box-Bhenken design and response surface methodology were used for designing of experiment and statistical analysis of the results. This procedure limited the number of actual experiments to 54 for studying the possible interaction between six nutrients. The optimum concentration of the nutrients were Sucrose 148.5 g/L, KH2PO4 0.50 g/L, NH4NO3 0.33 g/L, MgSO4 0.41 g/L, Zn 23.76 mg/L, Fe 0.18 mg/L for Aspergillus niger to achieve maximum bio-recovery of manganese (82.47 ± 5.67%). The verification run confirmed the predicted optimized concentration of all the six ingredients for maximum bioleaching of manganese and successfully confirmed the use of Box-Bhenken experimental design for maximum bio-recovery. Results also revealed that small and less time consuming experimental designs could be efficient for optimization of bio-recovery processes.
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Catalytic Pyrolysis of Waste Inner Rubber Tube into Fuel Oil Using Alumina and Calcium Carbonate Base Catalysts

FARAH JABEEN ,ZAHID HUSSAIN ,JASMIN SHAH ,MOHAMMAD RASUL JAN ,FAZAL MABOOD ,

The waste inner rubber tube represents a source of energy and valuable hydrocarbons were catalytically pyrolysed in a batch reactor under atmospheric pressure. For this catalytic pyrolysis two economical base catalysts like Al2O3 and CaCO3 were used. The effects of these twocatalysts were determined in term of the yield of the derived gas, liquid oil, and solid char products. The liquid obtained from catalytic pyrolysis of waste inner rubber tube termed as parent oil was also refluxed with their respective catalyst for 2 hours. For the comparison both of the oil that is parent and refluxed oil were also characterized by physical and chemical tests. In case of using Al2O3 as a catalyst, the oil product containing higher concentration of polar hydrocarbons. As far as the distillation data and fuel tests are concerned, the oil fractions with both the catalysts fulfill thepresent specifications of diesel fuel commercial products.
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Synthesis and Characterization of Polyimide-Epoxy Hybrid Films

MUHAMMAD ZAFAR-UZ ZAMAN ,ZAREEN AKHTER ,MUHAMMAD SAEED BUTT ,MUHAMMAD SHOAIB ,HUMAIRA MASOOD SIDDIQI ,

Composites from polyimide and epoxy-amine were prepared aiming for enhancing its thermal and mechanical properties. Polyimide-epoxy-amine hybrid films were prepared by blending of polyimide and epoxy-amine in different ratios whereas, polyimide was prepared by reacting 1,2-di(p-aminophenyloxy)ethylene with 3,3¢4,4¢-benzophenone tetracrboxylic acid dianhydride. The blend systems with Araldite LY564 (1,4-butanediolediglycidyl ether) (BDDE) and Hardener HY2954 (3,3¢-dimethyl-4,4¢-diaminodicyclohexyl)methane (MACM) were investigated in term of thermal, mechanical and viscoelastic measurements. Thermal stability was determined using thermogravimetric analysis. The effect of the polyimide content on the glass transition temperature (Tg) and thermal stability was observed. Viscoelastic measurements showed that the glass transition temperature shifted with the increase of polyimide content. The composites showed higher thermal stability in comparison with neat epoxy-amine matrix for higher polyimide concentration. The effect of polyimide content on the mechanical properties was also investigated. The tensile measurements of the films showed that with the increase of polyimide content the tensile modulus of the films was increased.
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Pharmacokinetic and Bioavailability Studies of Commercially Available Simvastatin Tablets in Healthy and Moderately Hyperlipidemic Human Subjects

MAHMOOD AHMED ,NAVEED AKHTAR ,MUHAMMAD ATIF ,MUHAMMAD QAMAR-UZ-ZAMAN ,GHULAM MURTAZA ,MUHAMMAD USMAN ,ASADULLAH MADNI ,

Simvastatin, an analogue of Lovastatin, is a HMG.CoA reductase inhibitor. It is widely used in the treatment of hyperlipidemia and coronary heart disease (CHD) with low incidence of myopathy and rhabdomyolysis. As these diseases may alter the pharmacokinetics of drugs, the present study was aimed to elaborate the variation in the pharmacokinetics and bioavailability of simvastatin in local healthy and moderately hyperlipidemic population. Open, single dose and parallel design was applied to study. A total of 36 male volunteers were used for healthy and moderately hyperlipidemic groups (n = 18 for each) in this study on the basis of screening procedures, body chemistry and physical examination. Simvastatin 40 mg tablets (Saista 40, Bosch, Pakistan) were administered to over-night fasted volunteers. Blood samples were collected before dosing (zero time) and at regular intervals of time. The plasma samples were processed through a liquid-liquid extraction procedure and assayed by using HPLC consisting reversed phase C18 column (ZORBAX,  4.6 x 150 mm, 5 µm), UV detector set at 238 nm. The mobile phase consisted of the mixture of 0.025 M sodium dihydrogen phosphate (pH 4.5): acetonitrile (35: 65, v/v) which was pumped at a flow rate of 1.5 mL.min-1. The retention time of simvastatin was 7.5 minutes. The plasma drug concentration-time profiles of both groups were found significantly (P < 0.05) identical. The data was analyzed by using Kinetica® version 4.4 according to non-compartment model of pharmacokinetic analysis. There was statistically no significant (P > 0.05) difference between the values of following pharmacokinetic parameters in healthy and hyperlipidemic volunteers i.e. Cmax, tmax, AUC0-∞, AUMC0-∞, MRT, t1/2, Clt and Ke. This study confirmed no significant (P > 0.05) difference in pharmacokinetics and bioavailability parameters after the administration of a single oral dose of 40 mg simvastatin (cholesterol lowering drug) to healthy and moderately hyperlipidemic volunteers.
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Reductive release of Fe(III) from Bovine Lactoferrin by Ascorbic Acid

SYED ARIF KAZMI ,SHAZIA NISAR ,

The kinetics of the reduction of Fe3+ from bovine diferric Lactoferrin (Fe2Lf) and monoferric C-terminal (FeC-Lf) and N-terminal (Lf-FeN) sites is investigated at pH 6.1 and 3.5 under pseudo first-order conditions using ascorbic acid (AA) as a biological reducing agent and 1, 10-Orthophenanthroline (O-phen) as Fe2+ chelator. Pseudo first-order rate constants as a function of ascorbic acid concentration are measured. Second order rate constants (k2) for Fe2Lf, Lf-FeN, FeC-Lf  at pH 6.1 and 27 °C are 0.1527 M-1.min-1, 0.0381 M-1.min-1, 0.1381 M-1.min-1, respectively. While, at pH 3.5 and 27 °C these values are 0.1915 M-1.min-1, 0.1116 M-1.min-1, 0.4434 M-1.min-1, respectively. A linear dependence of kobs on ascorbic acid concentration is suggestive of simple pseudo first-order pathway for reduction of iron under the conditions applied for all the three forms of protein.  Moreover, the results show that the C-terminal site is more labile toward reduction by ascorbic acid than the N-terminal site.
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The Sulfide Oxidation in an Electrolytic Sulfide Oxidizing Bioreactor using Graphite Anode

QAISAR MAHMOOD ,AFSAR KHAN ,DONGLEI WU ,QINHAI HU ,LILI WU ,

The goal of the present research was the direct conversion of sulfide (an important contaminant in various industrial wastewaters) to sulfate, whose discharge limits are much less stringent than those for sulfide. The electrolysis of sodium sulfide was investigated under different conditions such as: pH, current density and working area etc. along with cyclic voltammetry. By the use of a graphite anode, we achieved near-quantitative electrochemical conversion of sulfide ions to sulfate with current efficiency of 88%. Kinetically, the reaction is first order in current density. The experimental results revealed that the sulfide removal rate of more than 88% could be achieved under the conditions T=30 ?, pH = 7, current density of 1mA/cm2 at anode area of 225 cm2.The process can be practically coupled with bioreactor for an effective sulfide removal.
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