VOLUME 35, NO6, DEC-2013

A Thermodynamic Investigation on the Binding of Lysozyme with Sodium Dodecyl Sulfate

The interaction of Sodium Dodecyl Sulfate (SDS) with hen egg lysozyme have been investigated at 298, 303 and 308 K in phosphate buffer at two different pH values (5 and 7), by isothermal titration calorimetry. The calorimetric data analysis allows the measurement of the complete set of thermodynamic parameters. The negative SDS ion binds to positive residues, neutralizes the protein surface charges and leads to precipitation and turbidity of the solution. At low concentrations of SDS, the binding is mainly electrostatic, with some simultaneous interaction of the hydrophobic tail with nearby hydrophobic patches on the lysozyme. The enthalpies of denaturation at pH 7 are 180.47, 198.51 and 216.56 for 298, 303 and 308 K respectively.read more

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Gholamreza Rezaei Behbeheni, Shahrbanoo Ramazani and Katayon Gonbadi

Influence of Dispersing Agent in Formation of Β-Dicalcium Silicate from Rice Husk

Present experimental work describes the synthesis of β-dicalcium silicate from rice husk by using dispersing agent during formation of calcium hydro silicate (CSH) gel. The growth of CSH gel retards the impeller mixing phenomenon. This type of problem can be resolved by using dispersing agent. Amorphous silica was obtained from HCl treated rice husk. Calcination temperature of rice husk was maintained at 600 oC for 90 minutes. In the presence of water, amorphous silica was treated with calcium oxide by using 0.2 % dispersing agent to develop CSH gel. The CSH gel was developed in oven for 12 hours at 90 oC followed by drying at 105 oC for 12 hours in an oven. Dried gels were heated up to 900 oC to obtain beta form of dicalcium silicate. The CSH gel and β-dicalcium silicate were examined by XRD, FTIR, SEM and TGA. It was observed that by using pretreated rice husk truly amorphous silica can be obtained. It was also observed that dispersing agent facilitated the formation of CSH gel. Observations further revealed that such amorphous CSH gel started converting into beta form of dicalcium silicate at 600 oC.read more

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Syed Hassan Javed, Mohsin Kazmi, Umair Aslam and Nadeem Feroze

Thermal and Thermo-Mechanical Behavior of Butyl based Rubber Exposed to Silicon Oil at Elevated Temperature

Silica reinforced rubbers are used as chemical resistant seals at high temperature. In this study the effect of alkali and silicon oil on the thermal and thermo-mechanical properties of the silica reinforced butyl rubber exposed as an interface between two liquid media at elevated temperature is investigated. Rubber bladder containing alkaline solution was immersed in silicon oil at 195±5oC for multiple cycles and loss in its thermal, thermo-mechanical and mechanical properties were studied by TGA, DMA and Tinius Olsen Testing Machine supported by FTIR and Optical microscopy. It was observed that the thermal and thermo-mechanical properties of butyl rubber were negatively affected due to leaching out of silica filler embedded in an organic matrix at elevated temperature. The thermal stability of exposed rubber was decreased around 200oC and the loss of storage modulus was observed up to 99.5% at -59oC.read more

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Shaukat Ali, Sadaf Ramzan, Ramsha Raza, Fiaz Ahmed, Shafiq Ullah, Rizwan Hussain and Saqib Ali

Efficiency Improvement of Electrospun TiO2 Nanofibers Based Double Heterojunction Organic Photovoltaic Devices by ZnO Cathode Buffer Layer

Polymer/fullerene solar cells with cathode buffer layer and double heterojunction electrospun metal oxide nanofibers are presented in this study. Electrospun TiO2 nanofibers on solution processed ZnO cathode buffer layer (CBL) are synthesized and introduced to inverted organic photovoltaic devices for improving their power conversion efficiency. It is found that a combination of ZnO (CBL) with electrospun TiO2 nanofibers covers a large wavelength range for light absorption and reduced device series resistance, which improved current density and fill factor of the devices. The structural and optical properties of the various structure/ layers are investigated by FESEM and UV-Vis spectrophotometer, while the devices were characterized under 1.5G illuminations by solar simulator. The resultant efficient inverted solar cells exhibit an open circuit voltage of 0.62V, short circuit current density of 12.98mA/cm2, fill factor of 0.53, and power conversion efficiency of 4.27±0.01%.read more

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Muhammad Tanveer, Amir Habib and Muhammad Bilal Khan

Optimizing the Shrinkage and Bursting Strength of Knitted Fabrics after Resin Finishing

Application of crosslinking resins is one of the effective methods used for improving the dimensional stability of cotton knitted fabrics. However, such an application often results in severe deterioration in the bursting strength of the treated fabrics. This study was undertaken for modeling and optimization of the shrinkage control and bursting strength of Lacoste Pique cotton knitted fabrics, using response surface methodology. A central composite experimental design was used to find out the optimum resin and softener concentrations along with the best curing time for maximum shrinkage control with minimum possible loss in the fabric bursting strength.read more

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Tanveer Hussain, Faiza Safdar, Ahsan Nazir and Kashif Iqbal

Comparative Hydrolysis Study of Acetylsalicylic Acid and Copper (II)-Acetylsalicylate by RP-HPLC Method

The hydrolysis of acetylsalicylic acid (ASA) and copper (II)-acetylsalicylate (CAS) was investigated by using a validated RP-HPLC method. Acetylsalicylic acid was hydrolyzed to (SA), where as CAS was hydrolyzed to ASA, SA, copper salicylate (CS), copper acetate and acetic acid. Comparison of hydrolysis was carried out by monitoring the concentration of SA, one of common hydrolysis product. The hydrolysis study was done in phosphate buffer solution in pH range from 3-11. The study was carried out at constant temperature to evaluate the effect of pH on both drugs. It was found that the hydrolysis rate of both drugs was same at pH value ranging from 3-11 as calculated from the Kapp and K values. However, there is a slight difference in the degradation of ASA and CAS as revealed from F-test. Results have indicated that CAS first hydrolyzes to acetylsalicylic acid which further hydrolyzes to SA, therefore availability of acetylsalicylic acid is increased.read more

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Muhammad Sher, Mohammad Saeed Iqbal, Muhammad Ajaz Hussain, Syed Gohar Taqi and Muhammad Rashid Hussain

Toxicity of Phthalate Esters in Fish and Shellfish

This study presents the outcome of an investigation on the occurrence of phthalates, in eight edible marine fish species from lower James River, Chesapeake Bay along the Virginia Coast of Atlantic ocean. These include shell fish like Crab(Callinectes sapidus), Clam( Merccnaria), Oyster(C.ariakensis), and white shrimp ( Litopenaeus vannamei) from aquaculture center of Virginia Tech. These were analyzed for their content of Dimethyl Phthalate, Diethyl Phthalate, Di-n-butyl Phthalate , butyl benzyl Phthalate , bis(2-ethylhexyl) Phthalate ,and di-n-octyl Phthalate Mean concentrations (range) of Di(2-ethylhexyl) phthalate (DEHP), Butyl benzyl phthalate (BBP) and di-n-butyl phthalate (DBP) in fish samples were 1.1 (<0.01-1.5), 0.22 (<0.01-1.1) and 0.14 (<0.01-1.3) µg g−1; those in shell fishery were 1.2 (<0.02-1.3), 0.13 (<0.01-0.27) and 0.09 (<0.02-0.22) µg g−1, respectively. The highest concentration of bis (2-ethylhexyl) Phthalate in fish samples were found in Atlantic mackerel (Centropristis striate) (1.98±0.92) µg/g (wet weight) and Oyster (C.ariakensis) (2.30 µg/g (wet weight), were higher than those in other fish species.read more

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Alia Bano Munshi, Nasim Karim, Sohail Shaukat, Durdana Hashmi, Gregory Dale Boardman and George Joseph Flick

Fourier Transform Infrared (FTIR) Analysis of Trapa bispinosa: A Novel Adsorbent for the Removal of Cu (II) from Aqueous Solution in Chemically Treated Form

Current study explored biosorption mechanism and kinetics of Cu (II) onto Trapa bispinosa peels (TBPs) biomass in surfactant (SDS, CTAB, and Triton X-100), organic acid (CA, TA, AA) and in Native (N) form during batch experiment. Equilibrium sorption capacity was determined at various solution parameters like pH, contact time and initial concentration. Increment in sorption capacity was observed with increase in pH until maximum is achieved at pH 5. Optimized time and concentration were 120 minutes and 100 ppm respectively. Best fitted pseudo-second order kinetic model on the data showed that sorption of Cu (II) is rate-controlling. Sorption capacity (mg g-1) for Cu (II) ions increased while % removal decreased. SDS TBPs in comparison to all TBPs show highest sorption tendency as after SDS pretreatment TBPs surface is loaded with the negatively charged groups that provide more attachment sites for Cu (II) ions. Langmuir isotherm give best description of monolayer adsorption over the surface as it fitted better to data. FTIR analysis showed presence of functional groups like amine, carbonyl and hydroxyl groups. Ionization states of these functional groups are changed with pH.read more

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Maryam Yousaf, Raziya Nadeem, Tahir Zahoor, Muzna Saeed, Muhammad Abid Rashid, Rashid Saeed and Ahmad Mukhtar Khalid

Analytical and Biological Studies of Kanji and Extracts of its Ingredient, Daucus carota L.

A fermented beverage, Kanji, prepared from roots of Daucus carota L. subsp. sativus (Hoffm.) Arcang. var. vavilovii Mazk. (Apiaceae), despite long usage history has not been investigated for analytical studies and biological activities. Therefore, the present study aimed to investigate different types of Kanji samples and various types of extracts/fractions of root of the plant for a number of analytical studies and in vitro antioxidant activities. The Kanji sample, Lab-made Kanji, having better analytical and biological profile was further investigated for preliminary clinical studies. The analytical studies indicated that Lab-made Kanji was having comparatively higher contents of phytochemicals than that of the commercial Kanji samples, different types of extracts and fractions (P < 0.05). All the Kanji samples and aqueous and ethanol extracts of fresh roots exhibited comparable antioxidant activities in DPPH assay (52.20 - 54.19%) that were higher than that of methanol extract (48.78%) of dried roots. The antiradical powers (1/ EC50) of Lab-made Kanji and aqueous extract were found to be higher than that of the ethanol and methanol extracts. In β-carotene linoleate assay, the Kanji samples showed higher activity than that of the methanol extract, but comparable to that of the vitamin-E and butylated hydroxyl anisole (BHA) (P < 0.05). A preliminary clinical evaluation indicated that Kanji has no harmful effect on blood components, liver function and serum lipid profile. The results of the present study indicate that Kanji is an effective antioxidant beverage.read more

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Abida Latif, Khalid Hussain, Nadeem Irfan Bukhari, Sabiha Karim, Amjad Hussain, Furqan Khurshid Hashmi, Rukhsana Sher, Syed Saeed-Ul-Hassan and Bashir Ahmad

Recycling Of Aluminum from Aluminum Cans

High purity salt flux composition and additive composition, which is used in the melting of scrap aluminum such as found in used beverage containers, have been optimized in this investigation. Results indicated that the use of temperatures from 450 to 950C and flux amount of at least 5 wt.% lead to good recovery of aluminum after the recycling of cans. Utilization of chlorides and fluorides in excess result in formation of craters and dendrites in the recovered metal, which denote that the magnesium and aluminum oxides in the form of drosses, a heterogeneous system, accumulate in these craters. A visual examination of the images shows visible holes which provide continuous channels to the internal surfaces of the metal to the atmosphere. It is observed that the oxidation of the internal surfaces and channels result into huge amount of drosses. The molten chlorides and fluorides in excess corrode this structure and break the oxide links, subsequently liberating the pure aluminum.read more

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Shakila Begum