VOLUME 37, NO1, FEB-2015

Modeling of the Water Uptake Process for Cowpea Seeds (Vigna Unguiculata L.) under Common Treatment and Microwave Treatment

The water uptake kinetics of cowpea seeds were carried out at two different water absorption treatments - common treatment and microwave treatment - to evaluate the effects of rehydration temperatures and microwave output powers on rehydration. Water uptake of cowpea seeds during soaking in water was studied at various temperatures of 20 - 45ºC, and at various microwave output powers of 180 – 900 W. As the rehydration temperature and microwave output power increased, the water uptake of cowpea seeds increased and the rehydration time decreased. The Peleg’s and Richards’ Models were capable of predicting water uptake of cowpea seeds undergoing common treatment and microwave treatment, respectively. The effective diffusivity values were evaluated by fitting experimental absorption data to Fick’s second law of diffusion. The effective diffusivity coefficients for cowpea seeds varied from 7.75×10-11 to 1.99×10-10 m2/s and from 2.23×10-9 to 9.78×10-9 m2/s for common treatment and microwave treatment, respectively.read more

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Elçin Demirhan and Belma Özbek

Fourth Order Connectivity Index of Hexagonal Chains

The higher order connectivity index is a graph invariant defined as h X (G)=Σu1 u2 u h+1 (du1 d u2 duh=1) -1/2, where the summation is taken over all possible paths of length h, and d u i denotes the degree of the vertex uI of the graph G. In this paper, we stick to researching the fourth order connected index of hexagonal chains and give a calculation formula and we characterize the extremal graphs with the extremal fourth-order Randi¢ index.read more

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Luozhong Gong, Meichun Zhao and Jing Chen

Production of Poly(Methyl Methacrylate) with Clariant Nuva HPC in Supercritical Carbon Dioxide as Enhanced Technology

Dispersion polymerization of methyl methacrylate (MMA) was carried out in supercritical carbon dioxide (scCO2) using Clariant Nuva HPC as stabilizer. Dry, fine powdered spherical polymethyl methacrylate particles (pMMA) were produced at optimised conditions. The resulting high yield of spherical and relatively uniform micron-size pMMA particles were formed utilizing various amounts of Clariant Nuva HPC. The effects of varying the concentration of stabilizer (1-7 w%), reaction time (4-48 h) and reaction pressure (15-35 MPa) upon the polymerization yield, molar mass and morphology of pMMA were investigated. The experiments were analyzed with Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The number-average particle size and particle size distributions were determined by measuring the diameters of 50–150 particles in the SEM images. The analyses results showed that the dispersion polymerization of MMA was carried out successfully by using Clariant Nuva HPC as flour-containing stabilizer.read more

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Nil Baran Acarali, Semra Ozkan and Salih Dincer

Supramolecular Interactions of Ionic Liquids with p-sulfonated calix[4]arene using a New Type of Fluorescent Probe

Coptisine (COP) emits weak fluorescence in acidic (pH 2) aqueous solution. However, a remarkable increase in fluorescence intensity is observed when p-sulfonated calix[4]arene (SC4A) is added to the aqueous solution. With the addition of ionic liquid, the aqueous solution of COP-SC4A complexes considerably quenches fluorescence intensity. The supramolecular interactions of SC4A with three types of 1-butyl-3-methylimidazolium ionic liquids (C4MIm+) were examined based on this fluorescent probe system. The 1-butyl-imidazolium moiety of ionic liquid was embedded in the SC4A cavity, and the counter anion slightly affected the binding capacity of the ionic liquid. 1H-NMR studies and molecular modeling theoretical calculations confirmed the formation of inclusion complexes.read more

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Hai Long Liu, Yan Zhao, Qian Du, Li Ming Du, Tao Tao Pang and Yun Long Fu

Influence of Sm-Mn Substitution on Structural, Dielectric and Electrical Properties of X-Type Hexagonal Nanoferrites

A series of Sm-Mn substituted X-type hexagonal ferrites with composition Sr2-x SmxNi2 Fe28-yMnyO46 (x=0.02, 0.04, 0.06, 0.08, .010 and y= 0.1, 0.2, 0.3, 0.4, 0.5) have been synthesized by sol gel method. The temperature at which required phase has been obtained was confirmed from the TGA/DSC analysis. X-Rays Diffraction analysis reveals the single phase of the prepared material. The lattice parameters and unit cell volume change with substitution of Sm-Mn contents. SEM and TEM analysis indicates that the crystallite size lies in the range of 60-80 nm. The dielectric constant decreases with the increase of frequency. The relaxation peaks in tangent loss curves indicates the presences of polarons in the material and make this material applicable in medium frequency (MF) devices. The results of electrical resistivity measurements indicate the enhancement in room temperature resistivity with the substitution of Sm-Mn contents. The increase in resistivity reflects the applications of synthesized material in microwave devices and reducing the eddy current losses.read more

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Imran Sadiq, Imran Khan, Evgeny V. Rebrov, M. Naeem Ashiq, Shahzad Naseem, Imran Shakir and Mazhar U Rana

Removal of Malathion from Various Waters by Advanced Oxidation Processes

The degradation of malathion was investigated under various conditions, including ultrasound (US) irradiation, ultraviolet (UV) irradiation, and the combination of US/UV, UV/ZnO, UV/H2O2, and US/UV/ZnO/H2O2. In addition, the effect of the operational parameters, such as the initial concentration of the catalyst, the initial malathion concentration, the initial salt concentration (NaHCO3 and Na2SO4), and pH, were studied. Analyses were performed by a gas chromatography-mass spectroscopy instrument. The k values were in the following order: US/UV/H2O2/ZnO > US/UV > UV/ZnO> UV/H2O2 > UV > US. ZnO concentration of 100 mg/l, malathion initial concentration of 200 µg/l, H2O2 concentration of 30 mg/l, pH of 9, and irradiation time of 105 min were the optimum conditions for degrading malathion by the US/UV/H2O2/ZnO system. Additionally, the optimized parameters were also tested for the treatment of an actual water sample containing the pesticide. As a result, the efficiency of the US/UV/H2O2/ZnO system was higher in the distilled water sample than in the actual water sample.read more

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Abdolmajid Fadaei and Mahdi Kargar

Mefenamic Acid Conjugates Based on a Hydrophilic Biopolymer Hydroxypropylcellulose: Novel Prodrug Design, Characterization and Thermal Analysis

Macromolecular prodrugs (MPDs) of mefenamic acid were designed onto a cellulose ether derivative hydroxypropylcellulose (HPC) as ester conjugates. Fabrication of HPC-mefenamic acid conjugates was achieved by using p-toluenesulfonyl chloride as carboxylic acid (a functional group in drug) activator at 80°C for 24 h under nitrogen atmosphere. Reaction was preceded under homogeneous reaction conditions as HPC was dissolved before use in DMAc solvent. Imidazole was used as a base. Easy workup reactions resulted in good yields (55-65%) and degree of substitution (DS) of drug (0.37-0.99) onto HPC. The DS was calculated by acid-base titration after saponification and UV/Vis spectrophotometry after hydrolysis. DS by both of the methods was found in good agreement with each other. Aqueous and organic soluble novel prodrugs of mefenamic acid were purified and characterized by different spectroscopic and thermal analysis techniques. The initial, maximum and final degradation temperatures of HPC, mefenamic acid and HPC-mefenamic acid conjugates were drawn from thermogravimetric (TG) and derivative TG curves and compared to access relative thermal stability. The TG analysis has indicated that samples obtained were thermally more stable especially with increased stability of mefenamic acid in HPC-mefenamic acid conjugates. These novel MPDs of mefenamic acid (i.e., HPC-mefenamic acid conjugates) may have potential applications in pharmaceutically viable drug design due to wide range of solubility and extra thermal stability imparted after MPD formation.read more

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Muhammad Ajaz Hussain, Rukhsana Kausar, Muhammad Amin and Muhammad Raza Shah

μ-Acetato / μ-Aqua Bridged Binuclear Vic-Dioxime C

A new amino vic-dioxime ligand, N,N′-[3,3′-{ethane-1,2-di-yl-bis(oxy)bis(3,1-phenylene)}bis(N′-hydroxy-)2-(hydroxyimino)-acetimidamide] (LH4) was synthesized by reaction of 1,2-bis(m-aminophenoxy)ethane and anti-chloroglyoxime. Then, its Cu(II), Ni(II), Co(III) and Cd(II) complexes were synthesized by the ligand and Cu(AcO)2.H2O, Ni(AcO)2.4H2O, Co(AcO)2.4H2O and Cd(AcO)2 metal salts, respectively. The ligand and its metal complexes were characterized by elemental analysis, FT-IR, 1H-NMR, UV-vis spectra, magnetic measurements and thermal analysis (TGA-DTA) techniques. All complexes were diamagnetic and binuclear. The Co(II) complex was oxidized to Co(III). While suggested structures of Cu(II) and Ni(II) complexes were found as square-planar, Co(III) and Cd(II) complexes were found as octahedral geometries.read more

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Sibel Duman and Memet Şekerci

A Study of Stable Graphene Oxide Dispersions in Various Solvents

The work on processibility and practical use of Graphene is expanding, so the need for stable dispersion of Graphene in different solvents is ever increasing. The dispersion behavior of Graphene oxide (GO) prepared by modified Hummer’s method was studied in ten different solvents namely Water, Tetrahydofuran(THF), Dimethyl formamide(DMF), Ethylene Glycol, Acetone, Pyridine, 2-Propanol, Methanol, Ethanol, and Dimethyl sulfoxide (DMSO). The effect of sonication and addition of surfactant (Sodium Cholate) on dispersion behavior was also investigated. Homogeneous dispersions were found in all freshly prepared GO solutions but they were short lived. The dispersions were then left as such for three weeks and after three weeks they were observed again. It was found that stable dispersions were left only in some solvents like Water, THF, DMF, Ethylene Glycol and Pyridine. Finally in a separate set of experiment we treated the GO solutions in all these solvents with surfactant (Sodium Cholate) and sonication (400 Hrs) to see the dispersion behavior. It was observed that stable dispersion remained only in few solvents like Water, DMF, Ethylene Glycol and Pyridine. These were most stable and showed no sedimentation or settling down of GO even after three weeks. These solvents are easily available and can be effectively used for dispersion formation and further processing of Graphene.read more

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Mohammad Saleem Khan, Abdul Shakoor, Gul Tiaz Khan, Sabiha Sultana and Abid Zia

Reactivity Study of Silicon Electrode Modified by Grafting Using Electrochemical Reduction of Diazonium Salts

The use of the hydrogenated surface of silicon is hampered by its chemical instability by surface oxidation. The researchers have attempted to modify this surface by direct grafting through the establishment of covalent silicon-carbon bonds from the reaction of chemical species on the surface. Different grafting methods can be implemented for the preparation of grafted surfaces. The choice of an electrochemical reaction allows fast grafting from the hydrogenated surface. We studied the formation of a phenyl layer by electrochemical reduction of aryl diazonium salts (BF4-,+N2-ph-OCH3) on a p-Si-H (111) electrode in an aqueous medium (0.05M H2SO4 + 0.05M HF). The grafting of an organic layer by reduction is confirmed by the observation of a cyclic voltammetry peak around -0.3V/SCE. In-situ infrared spectroscopy (IR) analysis allows to identify the chemical functions present on the grafted surface, allowing a direct monitoring of the grafting reaction.read more

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Abdelkader Kaiber, Mohammed Cherkaoui, Jean-Noel Chazalviel, François Ozanam