Syntheses and characterization of blend membranes of sodium alginate and poly(vinyl alcohol) for the pervaporation separation of water + isopropanol mixtures

The blend membranes of sodium alginate and poly(vinyl alcohol) have been prepared by physical mixing in different ratios (75, 50, and 25%) of sodium alginate with poly(vinyl alcohol). The membranes were crosslinked with glutaraldehyde and used in the pervaporation separation of water + isopropanol mixtures at 30°C. The crosslinking reaction was confirmed by Fourier transform infrared spectra. Permeation flux increased with an increase in mass % of water in the feed mixture as well as with an increase in the amount of poly(vinyl alcohol) in the blend, but separation selectivity decreased. Diffusion coefficients of water + isopropanol mixtures have been calculated using the Fick's equation from the sorption data. Arrhenius activation parameters were calculated for 10 mass % of water in the feed mixture using the values of flux and diffusion coefficients obtained at 30, 40, and 50°C. The diffusion and pervaporation results have been explained on the basis of solution‐diffusion principles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3642–3651, 2002     

Understanding user privacy expectations: A software developer’s perspective

Software developers are trained to develop and design software applications that provide services to users. However, software applications sometimes collect users’ data without their knowledge. When applications collect and use users’ data without transparency, this leads to user privacy invasions because users do not expect the application to collect and use these information. Therefore, it is important that software developers understand users’ privacy expectations when designing applications in order to handle user data transparently in software applications. However, due to the lack of systematic approaches to extract user privacy requirements, developers end up designing applications either based on their assumptions on user privacy expectations, or relating to their own expectations of privacy as a user. Nevertheless, how accurate these perceived privacy expectations are against actual user expectations is not currently known. This research focuses on investigating developers’ privacy expectations from a user point of view against users’ privacy expectations. We also investigate developers’ assumptions on user privacy expectations against actual user privacy expectations. Our findings revealed that developers’ assumptions on user privacy expectations are close to their own expectations of privacy from a user point of view and that developers’ privacy expectations from a user point of view are significantly different from actual user privacy expectations. With this understanding, we provide recommendations for software developers to understand and acknowledge user expectations on privacy when they design and develop applications.     

Enhancing the electrochemical performance of ZnO anode by novel additive of MoS2–SnO2 nanocomposite for the zinc alkaline battery application

Journal of Materials Science: Materials in Electronics - ZnO nanorods and ZnO microrods are synthesized as the anode material for the Zn alkaline battery application. The present work studies the...     

Advanced lumber manufacturing model for increasing yield in sawmills using GPR-based defect detection system

This paper proposes an advanced lumber manufacturing model for real-time process control in saw mills in order to increase the yield of high value defect-free lumber. Detecting subsurface defects by scanning canted logs and generating a process plan to cut the logs can increase the yield of high-grade lumber in a saw mill industry. The defect detection process is performed using the ground-penetrating radar (GPR) system. More recently, a defect detection algorithm was developed to process GPR scanned data using the MATLAB? software. This research uses the distance and depth coordinates generated by the defect detection algorithm to develop the process plan that generates a cutting sequence for the resaw machine. The process plan is in the form of an algorithm written in MATLAB? with a simple user interface. The generated cutting sequence was validated by comparing to the conventional sawing sequence, where the operator of the resaw machine randomly performs the cutting of boards. An increase in the yield (in terms of dollar value) of about 27% was noticed using the GPR-based detection system which can map interior defects prior to sawing the log and enable an optimal sawing pattern.     

Optimisation of ethanol modified supercritical carbon dioxide on the extract yield and antioxidant activity from Garcinia mangostana L.

Xanthones are an important class of secondary metabolites present in mangosteen fruit pericarp. Herein we have used supercritical fluid technology to extract the active constituents from mangosteen pericarp. Ethanol was added (5% w/w) as a co-solvent to increase the polarity of the CO₂, thus favouring the extraction of xanthones. The maximum extraction yield of 15 wt.% was achieved at a pressure of 280 bar, temperature of 50 °C and a time of 8 h, while without co-solvent the yield was 7.5 wt.%. Conditions for antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay was 280 bar at 50 °C and 5 h. Box–Behnken design was used to study the efficiency of extraction pressure (180, 280, and 380 bar), temperature (40, 50, and 60 °C) and time (2–8 h) on the total extraction yields and their radical scavenging activity. Experimental results of the total extract yield and radical scavenging activity were close to the predicted values calculated from the polynomial response surface models equations (R² = 0.99 and 0.98).     

Microstructural studies in low specific energy laser surface treated Al(A356)-SiCP composites

SiC particulate reinforced A356 Al metal matrix composites were laser treated using pulsed Nd-YAG laser beam. The processing was carried out in air atmosphere at varying pulse energy (5 to 20 J) and scan rates (30 to 150 mm/sec). The samples were cut perpendicular to the track and they were characterized using optical microscopy, scanning electron microscopy and X-ray diffraction. Microstructure of laser treated region consists of regular succession of coarse and fine microstructure signifying the presence of low velocity bands. Transition from cellular/columnar dendritic to equiaxed dendritic structure has been observed. Microstructure of samples laser treated with specific energy greater than 13 kJ/cm² show presence of Al₄C₃ platelets.     

Optimal large linear complexity frequency hopping patterns derivedfrom polynomial residue class rings

We construct new sequences over finite rings having optimal Hamming correlation properties. These sequences are useful in frequency hopping multiple-access (FHMA) spread-spectrum communication systems. Our constructions can be classified into linear and nonlinear categories, both giving optimal Hamming correlations according to Lempel-Greenberger (1974) bound. The nonlinear sequences have large linear complexity and can be seen as a generalized version of GMW sequences over fields     

Absorption and Emission Spectral Analysis of Sm3 : Bi2O3-B2O3-Li2O Glasses

In order to enhance UV-transmission ability of B₂O₃ based glass, a suitable quantity of Bi₂O₃ and Li₂O salts have been added and hence the UV cut-off wavelength of Bi₂O-B₂O₃-Li₂O glass (abbreviated as BBL glass) has been found to be 268 nm. In this newly developed glass a luminescent rare earth ion namely Sm³⁺ (1 mol.%) has been incorporated to examine its absorption, excitation, emission and lifetimes of different measured emission bands. Under an UV-source, it has displayed a bright orange emission color. Apart from understanding its various optical properties, different physical properties of the un-doped reference glass have been investigated. The XRD profile of this glass has confirmed its amorphous nature. The measured excitation spectrum has shown a bright excitation band at 483 nm with which, the Sm³⁺ glass has been excited and thus obtained four emission bands at 563 nm, 598 nm, 648 nm and 709 nm respectively. An energy level diagram has been shown to explain the emission process involved in the glass system investigated in the present work.

Communicated by Prof. Jinzo Kobayashi     

Oxidative stability of oil from blubber of harp seal (Phoca groenlandica) as assessed by NMR and standard procedures

Oils from seal blubber and cod liver were extracted, refined and bleached in a laboratory scale process. Oxidative stability of oils was evaluated over a 16-day period under accelerated oxidation conditions at 65°C. Peroxide value (PV), contents of conjugated dienes (CD) and trienes (CT), 2-thiobarbituric acid reactive substances (TBARS) and p-anisidine values (AnV) were determined. In addition, NMR spectroscopy was used to monitor relative changes in the proton pattern of the fatty acids of oils during storage. Cod liver oil showed higher PV, CD, CT and TBARS values as compared with seal blubber oil. The ratio of aliphatic to olefinic protons in both oils determined by NMR spectroscopy increased steadily over the entire length of the storage period, indicating progressive oxidation of unsaturated fatty acids in both oils. A significant correlation (P ≤0·05) was found between these ratios and TOTOX values (2PV + AnV) for both oils, thus suggesting that NMR methodology can be used as an effective means to simultaneously estimate both primary and secondary oxidation changes.     

Hall current,radiation absorption,and diffusion thermoeffects on unsteady MHD rotating chemically reactive second-grade fluid flow past a porous inclined plate in the presence of an aligned magnetic field,thermal radiation,and chemical reaction

In this paper, we analyze the effects of Hall current, radiation absorption and diffusion thermo on unsteady magnetohydromagnetic free convection flow of a viscous incompressible electrically conducting and chemically reacting second-grade fluid past an inclined porous plates in the presence of an aligned magnetic field, thermal radiation, and chemical reaction. An exact analytical solution of the governing equations for fluid velocity, fluid temperature, and species concentration subject to appropriate initial and boundary conditions is obtained using the perturbation technique. Expressions for shear stress, rate of heat transfer, and rate of mass transfer at the plate are derived. The numerical values of primary and secondary fluid velocities, fluid temperature and species concentration are displayed graphically, whereas those of shear stress and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. In addition, the skin friction on the boundary, the heat flux expressed in terms of the Nusselt number, and the rate of mass transfer described in the Sherwood number are all derived, and their behavior is studied computationally. It can be deduced that an increase in radiation absorption and hall current parameters over the fluid region increases the velocity produced. The resulting velocity continually increases to a very high level, with contributions coming from thermal and solutal buoyancy forces. Skin friction may decrease by manipulating the rotation parameter, but the Hall effect can worsen it. When the parameter for the chemical reaction increases, there is a concomitant rise in the mass transfer rate.