VOLUME 40, NO1, FEB-2018

Fascinating Shape Memory Alloys

This is a brief review of the Fascinating Shape Memory Alloys, commonly known as smart metal, memory metal, memory alloy, muscle wire, smart alloy. A shape memory alloy is a microtome alloy so as to remember (keeps memory) it’s initial or real shape and when heated or deformed turns in to its pre-deformed shape. Because of its unique properties, Shape Memory Alloys have found wide usage in hydraulic, pneumatic and motor-baked systems. These alloys contain applications to robots and automobile, aerospace as well as biomedical application. This article not only covers the discovery of the shape memory alloys but also the fundamental principles behind this phenomenon, the various metals and alloys exhibiting the characteristics. Physical phenomena and their applications are also discussed.read more

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Iqra Zubair Awan

A nonlinear QSAR Study Using Oscillating Search and SVM as an Efficient Algorithm to Model the Inhibition of Reverse Transcriptase by HEPT Derivatives

Quantitative structure-activity relationships were constructed for 107 inhibitors of HIV-1 reverse transcriptase that are derivatives of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT). A combination of a support vector machine (SVM) and oscillating search (OS) algorithms for feature selection was adopted to select the most appropriate descriptors. The application was optimized to obtain an SVM model to predict the biological activity EC50 of the HEPT derivatives with a minimum number of descriptors (SpMax4_Bh (e) MLOGP MATS5m) and high values of R2 and Q2 (0.8662, 0.8769). The statistical results showed good correlation between the activity and three best descriptors were included in the best SVM model. The values of R2 and Q2 confirmed the stability and good predictive ability of the model. The SVM technique was adequate to produce an effective QSAR model and outperformed those in the literature and the predictive stages for the inhibitory activity of reverse transcriptase by HEPT derivatives.read more

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Ahmed Allali, Fouad Ferkous, Khaireddine Kraim, Youcef Saihi, Mohammed Brahimi Faouzi Zaiz and Ouassila Attoui-Yahia

Microchannel as a Green Processes, Compared to Conventional Methods for Extraction of Quercitannin

In the present study, a comparison was made among the efficiencies of four common extraction methods used for extraction of Quercitannin content of oak leaves. These extraction methods are Maceration, Soxhlet, and microfluidic extraction without and with ultrasonic wave irradiation. Several solvents including methanol, ethanol, hexane, and water were used during the experiments. Amount of Quercitannin obtained through a microchannel in the ultrasonic bath was higher than those of Soxhlet, Maceration, and plain ultrasonic bath extractions. This study is also aimed to study the extraction factors including frequency, temperature, and power ultrasonic in a microchannel with ultrasonic wave irradiation. Moreover, the optimal possible hybrid of these factors over response surface methodology was obtained. The optimum condition was the ultrasonic treatment at frequency = 80 kHz, temperature = 75ºC and power = 40w. Under these conditions, the yield using ultrasonic bath with microchannel was increased 17.57% and 32.68% compared with the plain microchannel and simple ultrasonic bath, respectively. The proposed continuous flow system uses less amount of solvent, producing less amount of waste. Besides, this system needs a smaller space compared with other conventional methods. Therefore, the use of microchannels as a way of the continuous method provides an environmentally friendly and high efficiency method in comparison with conventional methods.read more

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Mahnaz Yasemi, Amir Heydarinasab, Masoud Rahimi and Mehdi Ardjmand

Performance of Nanoporous Carbon Membrane for Hydrogen Recovery

The aim of this work is to study the performance of nanoporous carbon membrane for hydrogen recovery from off-gas streams. The study is based on a rigorous mathematical model which can predict the performance of nanoporous selective surface flow (SSF) carbon membrane. Basically, the developed model is based on two transport mechanisms: the dusty gas flow through porous media and the surface adsorption-diffusion. The model was employed to simulate the hydrogen recovery from off-gas stream using SSF carbon membrane at different operating conditions. The separation performance of hydrogen-hydrocarbon mixture by nanoporous carbon membrane was evaluated and described. A comparison between the model simulation and the experimental data related to hydrogen recovery from off-gas streams shows good agreement. A parametric study is further carried out to show the effects of pressure at the membrane feed and permeate sides. The effects of flow-rate and type of sweep gas at the membrane permeate side on hydrogen recovery are also shown. SSF membrane illustrates a significant potential to be used for hydrogen recovery from refinery off-gas streams.read more

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Abdulrahman A. Al-Rabiah, Abdelhamid M. Ajbar, Moustafa A. Soliman, Omar Y. Abdelaziz

Thermodynamic Interactions and Characterization of Poly (Acetyl Benzofuran Methylmethacrylate) and Poly(Acetyl Benzofuran Methylmethacrylate-co-Acrylonitrile) by Invers Gas Chromatography

In this study, the thermodynamic and physical properties of poly(acetyl benzofuran methylmethacrylate) [poly(ABM)], poly(acetyl benzofuran methylmethacrylate%41-co-acrylonitrile) [poly(ABM%41-co-AN)] and poly(acetyl benzofuran methylmethacrylate%71-co-acrylonitrile) [poly(ABM%71-co-AN)] were researched by using inverse gas chromatography. Two groups of alcohols and alkanes with different chemical natures and polarities were used to determine certain properties of [poly(ABM), poly(ABM%41-co-AN) and poly(ABM%71-co-AN)]-solute systems. The specific retention volume, Vg0, glass transition temperature, Tg; adsorption enthalpy, ∆Ha; the sorption enthalpy, ∆H1S; sorption free energy, ∆G1S; sorption entropy, ∆S1S; the weight fraction activity coefficients of solute probes at infinite dilution, Ω1, partial molar enthalpy of solute probes at infinite dilution, ∆H1∞; and Flory-Huggins interaction parameters, χ12∞; between polymer and solvents were determined in the temperature range of 493-343 K for poly(ABM) and 473-343 K for poly(ABM%41-coAN)-poly(ABM%71-coAN). Also, the solubility parameters of poly(ABM), poly(ABM%41-coAN) and poly(ABM%71-coAN) at infinite dilution were found out by plotting the graph of [12 – (∆G1∞/V1)] versus solubility parameters, 1, of the probes.read more

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Mustafa Hamdi Karagöz and Özkan Bolat

Synthesis and Characterization of Kaolin Assisted Metal Nanocomposite and its Tremendous Adsorptive and Photo Catalytic Applications

The present work demonstrates the synthesis of Kaolin assisted Ag nanocomposite (Ag-KNC) by co-precipitation method. The surface morphology of them was studied through SEM and chemical constituents by EDS techniques. The removal of efficaciousness of Ag-KNC was tested by Malachite Green Oxalate (MGO) dye through batch adsorption and photocatalytic strategies. The sorption experiments were preceded under the optimized conditions like amount of adsorbent, stay time and pH. The feasibility of the process was determined by employing Freundlich, Langmuir and D-R (Dubinin –Radushkevich) adsorption isotherms. The pH at point of zero charge (pHpzc) was conjointly calculable to work out the surface neutrality of the system. The salt effect for the removal of MGO dye was investigated. Thermodynamic parameters like free energy (∆Go), entropy (∆So) and enthalpy (∆Ho), of the system was investigated. Adsorption Kinetic was resolute by Intra particle diffusion (IPD) and Boyd’s models. An attempt was made to prepare (Ag-KCN) nanophoto catalyst by UV light assisted degradation of Malachite Green Oxalate (MGO) dye. They were prepared by the reduction of Ag+ ion under alkaline conditions on kaolin surface. The photo degradation (PD) process was initiated by photo generated electrons. The present study recommended that projected strategies were successfully applied for the remediation of environmental problems.read more

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Hajira Tahir, Muhammad Saad, Atika Saud and Uzma Saleem

Partial Oxidation of Ethane to Acetic Acid using a Metallic Pd Promoted MoVNb Catalyst Supported on Titania

The partial oxidation of ethane to acetic acid on a multi-component Mo16V6.37Nb2.05Pdx oxide catalyst supported on Degussa P25 titania has been investigated. The catalyst was characterized using BET surface area, X ray diffractometer (XRD) and transmission electron microscopy (TEM). The reaction was carried out in a differential reactor in a temperature range of 200-275°C and at a total pressure of 200 psi. The addition of trace amounts of nano-palladium, either as palladium oxides or metallic palladium, enhanced ethane oxidation towards the formation of acetic acid with near-complete depletion of the ethylene intermediate from the reactor effluent. The introduction of nano-Pd0 to Mo16V6.37Nb2.05Ox/TiO2 decreased the required palladium source to a third when compared with nano-PdOx. A green method was applied to prepare metallic nano-palladium using polyethylene glycol (PEG) and palladium acetate. PEG acted as a stabilizer and as a reducing agent. Transmission electron microscope (TEM) images of palladium nanoparticles showed an average size of approximately 15 nm. The as-prepared palladium nanoparticles were found to be highly stable.read more

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Sulaiman I. Al-Mayman, Abdulrahman S. Al-Awadi, Yousef S. Al-Zeghayer and Moustafa A. Soliman

Retention Characteristic of Ranitidine Hydrochloride on New Polymer-Based in Zwitter Ion Chromatography-Hydrophilic Interaction Chromatography Stationary Phases

Two zwitterionic stationary phases with largely corroborated capacities were obtained by attachment sulfobetaine monomers (H2C=CHC6H4CH2N+(CH3)2-CH2-SO3- and H2C=CHC6H4CH2N+(CH3)2-(CH2)5-SO3-) onto a PS/DVB particles were investigated for chromatographic separation of ranitidine hydrochloride. The different chain lengths are used as an investigative tool for the retention behavior of pharmaceutical ranitidine hydrochloride. The retention behavior of ranitidine hydrochloride was examined with eluent at various ACN contain, buffer concentrations and pH. The separation mechanism is based on partitioning in reversed phase and ZIC ion exchange resulting in a mixed mode for the ranitidine hydrochloride. A direct calibration graph was constructed for ZIC1 and ZIC5 columns and it was found that the linear range (10-1000 ng.ml-1), RSD% (0.41-1.55), LOD (1.55 and 2.56 ng.ml-1), LOQ (5.17 and 8.53 ng.ml-1), Recovery% (101.06 ± 1.15 and 100.47 ± 0.12) and Erel% (1.666 ± 0.78 and 0.47 ± 0.12), respectively.read more

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Marwah Adnan Abbas and Ashraf Saad Rasheed

Catalytic Oxidation of Toluene Using Co-MCM-48 and CoMn-MCM-48 Mesoporous Material

Mesoporous materials are widely used as catalysts, adsorbents and supports due to their advantages such as narrow pore size distribution, large surface area and long-range order. In the present study, MCM-48 mesoporous material was synthesized at room temperature by using cetyltrimethylammoniumbromide as a structure directing agent. The catalytic activity of MCM-48 was improved by the incorporation of either single metal (Co) or two metal atoms (Co and Mn). Techniques such as SEM, TGA, BET and FTIR were used to characterize the as synthesized catalysts. The catalytic activity of the as prepared catalyst was investigated for the oxidation of toluene using hydrogen peroxide as an oxidizing agent and the reaction products were analyzed by gas chromatography and mass spectrometry. The results revealed that only benzaldehyde was obtained over Co-MCM-48 while a mixture of benzaldehyde and benzyl alcohol was obtained over CoMn-MCM-48. These results confirmed that both catalysts have high stability and activity for the oxidation of toluene.read more

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Sana Ahmad, Khushnood Yasin and Asma Tufail Shah

Synthesis and Characterization of uniform Fine particles of Manganese Oxide and its Morphological Stability towards Calcination Rates

Fine particles of manganese oxide were synthesized by following the controlled precipitation method. For this, an aqueous solution of manganese chloride (0.01–0.06 molL-1) were allowed to react with an aqueous solution of ammonium carbonate (0.01–0.03 molL-1) at various temperatures (25-60 ºC) for different periods of time (10-40 min) with and without agitation (magnetic stirring/sonication). It was observed that the applied experimental parameters significantly affected different properties of the obtained solids. Extensive optimization of experimental parameters led to produce powders, composed of particles of uniform morphological features. The targeted particles were achieved only under limited experimental conditions. Selected batches were calcined at the elevated temperature (800 ºC) with the controlled heating rate of 5, 10 and 15ºC/min). Scanning electron microscopic analysis and X-ray diffractometry of the calcined materials showed that neither the heating rate nor the final temperature affected the original morphology of the particles. Moreover, the same batches of the solids were also characterized by FTIR, XRD, and TG/DTA. It was found that the as synthesized particles were highly alike in morphology but were weakly crystalline in nature. However, heat treatment of the obtained particles resulted in Mn2O3 particles of orthorhombic crystal system of high crystallinity.read more

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Khalida Akhtar, Syed Sajjad Ali Shah, Muhammad Gul, Ikram Ul Haq and Naila Zubair