VOLUME 32, NO3, JUN 2010

Effect of Orientation of Glass Fiber on Mechanical Properties of GRP Composites

Glass Fiber Reinforced polymer matrix composites are one of the most important engineering materials required for a variety of advanced and sophisticated applications in modern industry. The two components of a GRP composites are the matrix (the continuous phase) and the reinforcing glass. The matrix itself does not provide the strength, but it serves to bond the reinforcing glass fibers and to transfer the load to the reinforcing phase. Glass reinforcements provide strength for the GRP composites that is why we can say that mechanical properties of GRP composites depends mainly on the orientation, amount and type of fiber reinforcement present in it. The main applications of GRP composites are in chemical industry as storage tanks, in aerospace industry, and mainly in construction industry as cladding over other construction materials and other non-load-bearing applications.In the present work different types of glass fabric like chopped strands and roving, were selected to study the effect of their different orientations on mechanical properties of GRP composites. Thickness of sheets and resin content were kept constant for all the samples. Hand lay up method was used for the production of GRP composite.The mechanical properties like tensile strength, impact strength and hardness along with density of the samples were investigated using tensile testing machine, densitometer, charpy impact testing machine and rockwell hardness tester respectively.read more

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MUHAMMAD IRFAN ,FARZANA HABIB ,KHURAM KHALID ,SHAHZAD ALAM ,WAQAS IQBAL ,

Study of Hydrodynamic and Non-Hydrodynamic Interaction Parameters for Water / PVP / PVA Ternary System by Solution Viscometry

Polymer-Polymer interaction parameters from a water soluble polymer-blend solution have been determined by viscometry at 25°C. The ternary system assayed is distilled water poly (N-vinyl-2-pyrrolidone) (PVP)/Poly (vinyl alcohol) (PVA). The intrinsic viscosity and the viscometric interaction parameters have been determined for the water/PVP/PVA ternary system. Experimental results obey the Huggins equation. Degree of miscibility of this ternary system was estimated on the basis of the signs of ?Kexp ,  (kappa) and the value of K12 a dimensionless quantity. The positive values of ?Kexp and , and the higher values of K12 than KH value of the individual polymers reveals the miscibility of PVP/PVA blends.read more

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SHER AKBAR ,GHULAM SARWAR ,

Synthesis of Dye-sensitized Solar Cell Using Nickel- tetraphenylporphrine as a Sensetizer

A dye-sensitized solar cell was prepared under facile conditions. For this, a wide range of metalloporphrines was investigated and consequently Ni-tetraphenylporphrine was selected because it gave the maximum output in terms of voltage, current, and power. The structures of the prepared dyes were determined by single crystal X-ray diffraction (SXD) method. The molar extinction coefficient (ε) of Ni-tetraphenylporphrine in chloroform was determined (3.3.6 x 105 dm3 cm-1 mol-1 at 413 nm). Glass electrode was made using dip-coating technique, which had resistivity of 12.5 Ocm coated with fluorine doped tin oxide (FTO) layer. It was analyzed by checking its transparency and electrical conductivity. Its compositional analysis and structural determination was carried out by X-ray powder diffraction (XRD). The analysis showed the crystalline structure of SnO2. Grain size calculations depicted the particle size of order of 2-5 nm. Scanning Electron Microscope (SEM) revealed the nanocrystals of SnO2. Its band gap was (3.8 eV). The UV-Visible spectrum showed high transparency of glass electrode. Thickness of the film (SnO2) was calculated by surface profilometery, and thickness obtained about 100 nm. Photoelectrochemical measurements indicated that the cell present short-circuit photocurrent (Jsc) of 90 A/m2, fill factor (FF = 0.37), photovoltage (Voc = 0.60 V), and overall conversion efficiency (h) of 2 % under standard test conditions (STC).read more

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SYEDA AMBAR YOUSAF ,MUHAMMAD ATHAR ABBASI ,VIQAR UDDIN AHMAD ,MUHAMMAD ASLAM AWAN ,AZIZ UR REHMAN ,MUHAMMAD JAVED IQBAL ,FAWAD AHMED ,MUHAMMAD ASIF IQBAL ,

Cathodic Voltammetry of Nitrobenzene at Titanium in Micellar Solution

The present study relates to electro-reduction of nitrobenzene in the presence of miceller aqueous solution of sodium dodecyl sulphate at titanium cathode, using cyclic voltammetric and titanium etching methods in a three-electrode system. Nitrobenzene gives single reduction peak (Ia) corresponding to the irreversible electrochemical reduction. However, at higher concentrations and lower sweep rates single peak splits into two cathodic peaks. These peaks correspond to reaction mechanisms, involving four-electron over-all change; first step, with one-electron transfer to form anion radical (peak I) similar to electron transfer observed in aqueous micellar media. While the second step involves protonation of anion radical followed by a three electron-addition (peak II) leading to the formation of phenylhydroxylamine. In the presence of SDS nitrobenzene solubilizes and reduces efficiently even at lower concentration; while in the absence of SDS reduction peak appears at relatively higher concentrations of nitrobenzene. This work targets the utility of titanium as cathode.read more

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INAM UL HAQUE ,MUQADDAS TARIQ ,

Quantification of V(IV)-Maltol Complex Using Cyclic Voltammetry

Cyclic voltammetry is used in the present research work for the quantitative study of BMOV, (bis(maltolato)oxovanadium(IV)), the compound which shows insulin like properties. Electrochemical study of BMOV was done using cyclic voltammetry at Pt electrode vs. Ag|AgCl reference electrode. This study was performed using NaCl, KCl and KNO3 as supporting electrolytes. Results reveal that the use of Pt electrode can be helpful to quantify this complex (2.0x10-4 to 16.0x10-4 M) and the method can be applied in the pharmaceutical quality control assay of the complex.read more

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HUMERA ANWER ,SYED AZHAR ALI ,ZAHIDA TASNEEM MAQSOOD ,

Gas Chromatographic Analysis of Tranexamic Acid in Pharmaceutical Preparation Using Ethyl Chloroformate as Derivatizing Reagent

Ethyl chloroformate (ECF) has been used as derivatizing agent for gas chromatographic (GC) determination of tranexamic acid (TA). The elution was from the column HP-5 (30 m x 0.32 mm i.d.) connected with flame ionization detection (FID). Linear calibration curves were obtained with 2-50 ng TA injection on the column. Aminocaproic acid (ACA) when present together with TA could also be separated and determined simultaneously. TA was determined from pharmaceutical preparation. Relative standard deviation (RSD) for analysis was observed within 0.1-0.4 %. The pharmaceutical additives and number of amino acid when present together with TA did not affect the determination of TA.read more

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KULSOOM UBEDULLAH ABBASI ,MUHAMMAD YAR KHUHAWAR ,MUHAMMAD IQBAL BHANGER ,

Physicochemical Characterization of Groundwater in Urban Areas of Lahore, Pakistan, with Special Reference to Arsenic

The current quality status of groundwater from Lahore was investigated using standard analytical methodologies. The physicochemical parameters included in the study were pH, alkalinity, electrical conductivity, TDS, hardness, bicarbonate, nitrate, chloride, fluoride, sulphate, phosphate and turbidity. The metals included in the study were Na, K, Ca, Mg, Fe, Pb and As. The waters ranged in pH from 7.50 to 8.20 and in conductance from 329 to 1090 µS/cm. The alkalinity and TDS of the groundwater vary from 2.80 to 8.20 m.mol/L and 198 to 762 mg/L, respectively. Most of the water samples were found to be genuinely hard (100 to 300 mg/L hardness) and have rather low chloride and fluoride concentrations. The bicarbonate and nitrate ranged from 140 to 410 mg/L and 0.70 to 2.00 mg/L, respectively. The average metal concentrations followed the order; Na > Ca > Mg > K > Fe > As > Pb. For As, the concentration ranged from 24.6 to 71.6 µg/L, with the mean concentration of 36.0 µg/L, thus exceeding the upper permissible safe limit of As (10 µg/L) laid down by WHO and USEPA. The correlation study showed significant relationships among various physicochemical parameters and selected metal pairs. Multivariate cluster analysis was used for the apportionment of the measured variables and it revealed both natural and anthropogenic intrusion in the groundwater.read more

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GULRAIZ AKHTER ,MUNIR HUSSAIN SHAH ,JAVED IQBAL ,NAZIA SHAHEEN ,ZULFIQAR AHMAD ,

Flow Injection Spectrophotometric Method for the Quantitative Determination of Humic Acid (HA) in Treated and Natural Waters

A double channel flow injection (FI) spectrophotometric method was established for humic acid (HA) determination in milligram levels in treated and natural waters. FI method was developed for the determination of humic acid by injecting 100 µL of humic acid into a carrier stream of sodium citrate phosphate buffer (0.05 M, pH 7.0) followed by the injection of 50 µL toluidine blue (TB) solution. Both reagents were allowed to mix at T-junction and passed through a 25 cm reaction coil tubing before passing through the flow through cell (10 mm light path, 30 µL volume). Change in absorbance was measured at 630 nm. The method was calibrated with standard solutions of HA from 0.5-60 mgL-1.The calibration curve showed two linearity trends one ranging 0.5-20 mgL-1 and the other ranging 20-50 mgL-1. The detection limit was 0.5 mgL-1 of HA, and relative standard deviation (rsd) of 5 replicate measurements was 0.294%.The developed method was successfully applied for the HA determination in water samples from drinking water plants, rivers, lakes and streams. The sampling rate was more than 80 samples h-1. The method proves to be simple, rapid, feasible and reproducible.read more

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MUHAMMAD SIRAJ ,AAMIR RASHEED ,TAHSEEN GHOUS ,

Comparative Study on the NO2 Bindings to (MgO)n and (CaO)n Clusters, n = 4, 6, and 9: Formation of Nitrite and Nitrate

A comparative study on MgO and CaO clusters toward NO2 adsorption have been investigated theoretically by the density functional theory, approach Beck3LYP. Bond lengths, bond angles as well as adsorption energies of the MgO−NO2 and CaO−NO2 modes are calculated for varieties of sites on the three model clusters. The results indicated that there is a weak bound involving the  (MgO)9 cluster to the magnesium cations at face site (0.32 eV) and edge site (0.36 eV), and found sensitive to the size of the cluster that (0.87 eV) and (1.23 eV) are obtained for (MgO)6 and (MgO)4, respectively. In contrast, the binding stabilities for NO2 towards surface nitrite formation reveal significantly different (1.37 eV) and (1.66 eV) are obtained for (CaO)4, and (CaO)9 clusters respectively. The NO2 adsorption was found also reactive on (CaO)9 forming nitrate species, and present slightly large binding energy compared to (MgO)9 clusters. The reason for the difference in binding energies is discussed in terms of cluster electro-positivity, and the nature of the highest occupied molecular orbital.  NO32− surface species is also characterized.read more

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FATHI HASSAN BAWA ,

Effect of Various Levels of Salinity on the Uptake of Macronutrients (N, P, K, Ca, and Mg) by the Roots and Shoots of Sunflower (Helianthus annuus L.) Hybrids

A pot culture experiment was conducted to study the effects of four different levels of salinity having osmotic potential of 0.00, -4.67, -9.35, and -14.03 bars on the uptake of macronutrients (N, P, K+, Ca2+, and Mg2+) by 2 hybrids of sunflower (Helianthus annuus L.). Salinity levels were achieved by dissolving calculated amount of NaCl, Na2SO4, CaCl2, and MgCl2 (4:10:5:1) in half strength Hoagland culture solution. Results suggested that salinity significantly (P<0.05) and linearly increased the uptake of macronutrients (except K+) both by roots and shoots. A significantly maximum amount of N, P, Ca2+ and Mg2+ for roots (16.80, 4.13, 40.03 and 10.28 g kg-1) as well as for shoots (26.70, 3.95, 37.52, and 15.62 g kg-1), respectively, were recorded in highest dose of salinity (-14.03 bars). This might be due to excess use of SO4-2 over Cl- ions in the culture media. Results further suggested that K+ uptake both by roots and shoots were significantly reduced by applied doses of salinity. A maximum reduction in both root (19.82 g kg-1), and shoot (10.52 g kg-1) were observed where highest level of salinity (-14.03 bars) was applied. This inhibitory effect on K+ uptake could be attributed to excess use of Na+ salts in the growth media. Results also showed that, sunflower hybrid DO-728 accumulated more P & K+ by their roots and shoots when compared with hybrid DO-730. Therefore, hybrid DO-728 could be rated as salt tolerant followed by hybrid DO-730 as salt sensitive. Results further suggested that based on grand mean values of all mentioned species of nutrients (including K+), shoot exhibited 1.027 % increased uptake over their roots.read more

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AZHAR HANIF ,ABDUL KABIR KHAN ACHAKZAI ,SAFDAR ALI KAYANI ,