VOLUME 34, NO1, FEB 2012

Hydrogen Absorption and Desorption Performance of Magnesium-Aluminium Alloys Produced by Powder Metallurgy

The main scope of this study is investigating the hydrogen storage and desorption performance of Mg: Al (90:10), Mg17Al12 and Mg2Al3 alloys using a volumetric method. In the experiments, hydrogen pressure introduced into a reference volume was at approximately 20 Bar. Mg-Al alloys were prepared by a powder metallurgy technique. Pressing pressure levels of alloys were altered as 200, 400 and 600 MPa. Upon XRD patterns, after the pressing and sintering, β-Mg2Al3 and Mg:Al(90:10) phases decomposed into γ-Mg17Al12, Mg and Al compositions. γ-Mg17Al12 was the main phase in the hydrogen absorption/desorption process. The highest absorption of hydrogen was observed in the Mg:Al (90:10) alloys. The hydrogen desorption performance of the alloys decreased with the increase of absorption performance. Therefore the lowest desorption was observed in the Mg:Al (90:10) alloys.read more

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Investigation of mechanical and electrochemical performance of multifunctional carbon-fiber reinforced polymer composites for electrical energy storage applications

Concept of structural supercapacitors, based on carbon fiber reinforced polymer composites, has been introduced that can act as a structural load bearing component as well as an electrical energy storing device simultaneously. This multifunctional carbon fiber reinforced structural supercapacitor are fabricated by using carbon fiber and glass fiber/filter paper as reinforcements and cross-linked polymer electrolyte as a matrix. Carbon fiber mats also simultaneously serve the role of electrodes in addition to reinforcement whereas the glass fiber mat/filter paper also act as an insulator to avoid the short circuiting of the carbon fiber electrodes. A polymer epoxy matrix is modified by introducing ions within the cross-linked structure in order to develop an optimized polymer electrolyte. Flexural tests of structural supercapacitor are conducted to evaluate the structural performance while charge/discharge tests are conducted to evaluate the electrochemical performance. Multifunctional structural supercapacitor is tested mechanically as well as electrochemically. A structural supercapacitor is fabricated with an energy density of 0.11 mWh/m3, a specific capacitance of 0.8 mF/cm3 and flexural modulus of 26.6 GPa simultaneously.read more

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Effect of Oleic Acid on the Permeation Kinetics of Diclofenac Diethylamine

In vitro permeation studies were done using modified Franz diffusion cell through rabbit skin and silicone membrane utilizing different ratios of oleic acid with diclofenac diethylamine (DDA) in normal saline and methanol mixture during present study. Solubility studies indicated linear increase in drug solubility with carrier concentration. The enhancing effect of all the enhancer’s ratios was found to be significantly greater than that of standard without enhancer (control). ‘Benchmark’ values with which to compare the performance of the vehicle are the flux values which were statistically no significant difference (P>0.05) across rabbit skin and silicone membrane. The input-rate values of all the ratios have shown a constant trend. The vehicles used were predominantly influencing the partition of the drug into the skin rather than the diffusion throughout the study. Consequently, changes in diffusion and/or partition may occur as a result of absorption or depletion of permeation enhancer inside the membrane/or skin over time which validates our results.read more

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SYED NISAR HUSSAIN SHAH ,MASHOOD AHMAD ,AMIR BADSHAH ,MAHBOOB RABBANI ,MUHAMMAD SALMAN ,

Development of Sensor Calibration against Standards using Measurement Software TestPointTM-CEC and Application to the Verification of pH Electrodes

The acquisition, processing and presentation of data from many commercial devices have been simplified by use of personal computers (PCs) and effective software in last decades. As compared to text-based languages, such as BASIC, dataflow programmation (LabVIEWTM) and graphical programming (TestPointTM) have been developed and widely used in diverse scientific fields. Here, TestPointTM is used to control via IEEE-488 interface a system voltmeter; pH measurement is a master variable in analytical chemistry and environmental studies. For precise and accurate measurements of pH, timely verification and calibration of pH electrodes are essentially required. However, the sensitivity of most commercial pH-meters (0.1 mV) is not high enough to check the deviation with respect to Nernst’s law. With this combination of a high resolution voltmeter and graphical programming, data are acquired and processed as follows: a moving average is computed to check if equilibrium is attained and statistical tests are performed to define the confidence interval of the slope of the regression straight line. This allows the user to compute the deviation from the ideal law, generally statistically significant and to verify pH electrodes against NBS standards, according to IUPAC recommendations. A control chart can be easily drawn to define when the electrodes must be replaced. The method and the code can be easily modified to calibrate other sensors.read more

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GUILHEM BOURRIÉ ,MUHAMMAD FARRAKH NAWAZ ,

Effect of Different Locations, Varieties and Micronaire Values upon the Non-Cellulosic and Metal Contents of Cotton

Cotton fibres contain naturally occurring non-cellulosic materials such as sugars, wax, metals and other organic species that may influence fibre characteristics, i.e. physical and chemical properties, yarn processing efficiency as well as product quality. Chemical and physical tests were conducted on raw cottons from different growing areas of Pakistan to determine the effect of different chemical components/materials on fibre properties, spinning performance and yarn properties. The present research study was planned to explore the location’s effect upon the non-cellulosic content of raw cotton and its ultimate effect on end product. In this concern four different growing areas (Multan, Bahawalpur, Rahim Yar Khan and Faisalabad), four cotton varieties CIM-473, CIM496, NIAB-111 and NIAB-999 with four micronaire values (4.4,4.6, 4.8 and5.0) were analyzed for wax, alcohol extractable, residual sugars, fibre ash contents and light metal content. Determined values were significantly correlated to spinning consistency.read more

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NASIR MAHMOOD ,MAHMOOD AHMED KHAN ,MUHAMMAD QAMAR TUSIEF ,DANISH IQBAL ,WAJID ISHAQUE ,

Carbon Dioxide Emission from Maize Straw Incubated with Soil under Various Moisture and Nitrogen Levels

A laboratory incubation experiment was conducted to investigate the decomposition of maize straw incorporated into soil amended with nitrogen (N) and moisture (M) levels. Clay loam topsoil amended with maize straw was adjusted to four initial nitrogen treatments (C/N ratios of 72, 36, 18, and 9) and four moisture levels (60%, 70%, 80% and 90 % of field capacity) for the total of 16 treatments and incubated at 20°C for 51 days. CO2-C evolved was regularly recorded for all treatments during entire incubation period. Results showed that the mixing of straw with soil accelerated decomposition rates and enhanced cumulative CO2-C production. The incorporation of straw brought about 50% increase in the cumulative CO2-C production as compared with controls. About 45% of added maize straw C was mineralized to CO2-C in 51 days. We conclude that incorporation of straw into soil along with the addition of N and moisture levels significantly affected CO2-C evolution, cumulative CO2-C, C mineralization and soil organic carbon deposition. The CO2 emission was in positive correlation with (R2=0.99) N, moisture and incubation time (days). The straw returning into soil may enhance carbon pools and, thus will improve soil and environmental quality.read more

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QAISAR HUSSAIN ,UMEED SINGH ,MASHOOQE TALPUR ,XIAOHONG TIAN ,SHAUKAT ALI ABRO ,

QuEChERS Extraction for High Performance Liquid Chromatographic Determination of pyrazosulfuron-ethyl in Soils

This paper described a simplified quick, easy, cheap, effective, rugged and safe (QuEChERS) approach for determination of pyrazosulfuron-ethyl (PE) from soil samples by high performance liquid chromatography/ultraviolet (HPLC/UV) detector. Optimized results were obtained dispersing soil in water, followed by the addition of 1% acetic acid (HOAc) in acetonitrile (MeCN), anhydrous magnesium sulfate (MgSO4) and sodium acetate tri-hydrate (NaOAc·3H2O), which was a modification of QuEChERS method without primary and secondary amine (PSA) and C18 sorbent. The results showed the recovery ranged from 70.8% to 99.0% and 83.5% to 86.4% with the relative standard deviations of 2.1% to 7.9% and 7.0% to 10.0% in Changsha and Nanning soil samples, respectively. The limit of detection (LOD) of the method was 0.05 mg/Kg. The limit of quantification (LOQ) was 0.1 mg/Kg.read more

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XIAOMAO ZHOU ,DONGQIANG ZENG ,YANHUI WANG ,HAI TIAN ,LIANYANG BAI ,HUIHUA TAN ,LIANGWEI DU ,

Impact of Equilibrating Time on Phosphate Adsorption and Desorption Behaviour in Some Selected Saline Sodic Soils

To investigate the effect of equilibrating time on phosphate adsorption and desorption on saline sodic soils a study was carried using three soil series from Dera Ismail Khan (Pakistan) district, namely Zindani, Tikken and Gishkori. These soils are alkaline calcareous in nature with greater Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR) values which classify them as saline sodic soils. The equilibrating time for the adsorption study was 8, 12, 16, 20, 24, 48 and 72 hours for two levels (5 mg L-1 and 100 mg L-1). For desorption study 1, 2, 3, 4 and 5 hours after 24 hours for low and high dilution.  Adsorption and desorption isotherms of phosphate were developed for these soils. The Gishkori soil showed the greatest rate of adsorption as compared with the other two soils. Applying Langmuir and Freundlich models to P adsorption data revealed that Freundlich equation (R2 = 0.99) showed a better fit over the Langmuir equation (R2 =0. 97) in the three soils.  The desorption curves varied similarly from each other. The amount of P adsorbed was different from that released back to the soil solution. The amount of adsorption increased with the time. Statistical analysis showed that the rate of adsorption for both 5 and 100 mg P L-1 was significantly different at P<0.05 at 16 and 20 hours and at P<0.01 beyond 20 hours. However, the rate of desorption was not significantly influenced by the equilibrating time as compared with the theoretical values of the three series. As the P – desorption curve did not coincide the P – adsorption curve, hence the availability of P to plant was adversely affected on its application.read more

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SANA ULLAH KHAN ,M. JAMIL KHAN ,QUDRAT ULLAH KHAN ,SAIFUR REHMAN ,

Estimation of Monosodium Glutamate by Modified HPLC Method in Various Pakistani Spices Formula

The concentration of monosodium glutamate (MSG) was evaluated in ten samples of formulated spices in Pakistan. The samples were analyzed by modified HPLC method after water extraction and derivatization of MSG by dinitrofluorobenzene (DNFB), using reversed phase C18 column, mobile phase was consisted of methanol: water (1:1) followed by UV detection at 254 nm. The standard curve of derivatized MSG of 500, 250 and 125 mg/mL was plotted to determine the quantity of MSG in spices samples. The peak of MSG was identified by comparing it with retention time of MSG standards, that is, 8.6 min. MSG concentration in different samples was in the range of 2.6-7.7%, showing a wide range of added MSG. Glutamate contents in the samples were in the permissible limit established by the European Directive, 95/2/CE. Furthermore, MSG levels in food prepared by the formulated Pakistani spices samples are also less than the largest palatable dose of MSG for humans.read more

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MEHREEN LATEEF ,KAUSER SIDDIQUI ,MUHAMMAD SALEEM ,LUBNA IQBAL ,

Kinetics Studies on Symplocomoside: A Urease Inhibitor

The mechanism of inhibition of jack bean and Bacillus pasteurii ureases was investigated by symplocomoside (1) which is a phenolic glycoside of salirepin series and has been isolated from Symplocos racemosa Roxb. Lineweaver-Burk, Dixon plots and their secondary replots showed that 1 was a non-competitive inhibitor of these enzymes. Ki values were found to be 77.60 ± 1.22 μM and 63.47 ± 0.92 μM against jack bean and Bacillus pasteurii ureases respectively.read more

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MUHAMMAD IQBAL CHOUDHARY ,AZIZ -UR- REHMAN ,MUHAMMAD ARIF LODHI ,VIQAR UDDIN AHMAD ,MUHAMMAD ATHAR ABBASI ,