Electrochemical impedance spectroscopic characterization of the oxide film formed over low modulus Ti–35.5Nb–7.3Zr–5.7Ta alloy in phosphate buffer saline at various potentials

Electrochemical impedance spectroscopic characterization of the low modulus Ti–35.5Nb–7.3Zr–5.7Ta alloy has been performed in phosphate buffer saline solution at 37 °C. Measurements were performed at various immersion intervals up to 720 h at OCP and also at various anodic potentials up to 2 V. The alloy exhibits a two time constant impedance response at the OCP and a one-time constant response at anodic potentials in the passive region. The thickness of the oxide film formed has been evaluated and the electrochemical interpretation of the results has been reported. Cyclic potentiodynamic profile of the alloy displays valve metal characteristics and the presence of a wide passive region that extends up to the maximum potential value of 2 V studied.     

Characterisation of a uranium ore using multiple X-ray diffraction based methods

Uranium bearing ores are often a complex mixture of minerals and compounds, a number of which are not of economic importance and are commonly referred to as gangue materials. In order to improve the efficiency of the dissolution stage of the overall uranium extraction process, a greater understanding of the minerals and compounds present in the ore is required. A greater knowledge of the gangue materials present is important as they can influence various aspects of the dissolution process such as providing potential adsorption sites for aqueous uranium species and through influencing the equilibrium of reactions involving aqueous uranium species. In this study the mineralogy of a uranium ore was investigated using a range of X-ray diffraction (XRD) based methods including in situ high temperature XRD and XRD using a synchrotron beam line. The results obtained from standard XRD (Cu Kα), high temperature XRD and synchrotron XRD (16.534 keV) were compared and a number of minerals were identified. The improved spatial resolution and intensity of the synchrotron data allowed for superior phase identification of a variety of minerals where standard X-ray techniques gave inconclusive results.     

Swelling behaviour of a geofiber-reinforced expansive soil

This paper reports the results of laboratory study performed on expansive soil reinforced with geofibers and demonstrates that discrete and randomly distributed geofibers are useful in restraining the swelling tendency of expansive soils. Swelling characteristics of remoulded expansive soil specimens reinforced with varying fiber content (f = 0.25% and 0.50%) and aspect ratio (l/b = 15, 30 and 45) were studied. One-dimensional swell-consolidation tests were conducted on oedometer specimens. Reduction in heave and swelling pressure was the maximum at low aspect ratios at both the fiber contents of 0.25% and 0.50%. Finally, the mechanism by which discrete and randomly distributed fibers restrain swelling of expansive soil is explained with the help of soil–fiber interaction.     

Kinetic Modelling of Colour Degradation in Tomato Puree (Lycopersicon esculentum L.)

The kinetics of colour (measured as Hunter ‘a’ value) degradation in tomato puree (Lycopersicon esculentum L.) has been studied over a temperature range of 50–120 °C (isothermal condition), and also during normal open pan cooking, pressure cooking and cooking in a newly developed and patented fuel-efficient ‘EcoCooker’ (non-isothermal condition). The degradation of colour as measured by Hunter ‘a’ value was found to follow first order kinetics. The temperature dependence of degradation was adequately modelled by Arrhenius equation. A mathematical model has been developed using the isothermal parameters obtained to predict correctly the losses of red colour from the time–temperature data of non-isothermal heating/processing method. The results obtained indicate a colour degradation of similar magnitude in all the three modes of cooking used in the study.     

Slip in flows of power-law liquids past smooth spherical particles

The effect of slip in flows of power-law liquids past smooth spherical particles is numerically studied by using Navier’s linear slip model. For computational simplicity, a sphere-in-sphere type computational domain has been chosen. Thus, the governing conservation equations of mass and momentum are considered in spherical coordinates. These are solved by using a finite difference method-based simplified marker and cell algorithm implemented on a staggered grid arrangement. The non-Newtonian terms of the momentum equation are discretized by a second-order central differencing scheme, whereas the convective terms are discretized by using QUICK scheme. The reliability and accuracy of the solver is established by comparing the present numerical results with the existing literature counterparts. Furthermore, extensive new results are obtained in the range of conditions for Reynolds number, Re: 0.1–200; power-law behavior index, n: 0.5–1.6; and a dimensionless slip parameter, λ: 0.01–100. Finally, effects of these dimensionless parameters on near surface flow kinematics are thoroughly delineated.     

Magnetic resonance image denoising using nonlocal maximum likelihood paradigm in DCT‐framework

The data acquired by magnetic resonance (MR) imaging system are inherently degraded by noise that has its origin in the thermal Brownian motion of electrons. Denoising can enhance the quality (by improving the SNR) of the acquired MR image, which is important for both visual analysis and other post processing operations. Recent works on maximum likelihood (ML) based denoising shows that ML methods are very effective in denoising MR images and has an edge over the other state‐of‐the‐art methods for MRI denoising. Among the ML based approaches, the Nonlocal maximum likelihood (NLML) method is commonly used. In the conventional NLML method, the samples for the ML estimation of the unknown true pixel are chosen in a nonlocal fashion based on the intensity similarity of the pixel neighborhoods. Euclidean distance is generally used to measure this similarity. It has been recently shown that computing similarity measure is more robust in discrete cosine transform (DCT) subspace, compared with Euclidean image subspace. Motivated by this observation, we integrated DCT into NLML to produce an improved MRI filtration process. Other than improving the SNR, the time complexity of the conventional NLML can also be significantly reduced through the proposed approach. On synthetic MR brain image, an average improvement of 5% in PSNR and 86%reduction in execution time is achieved with a search window size of 91 × 91 after incorporating the improvements in the existing NLML method. On an experimental kiwi fruit image an improvement of 10% in PSNR is achieved. We did experiments on both simulated and real data sets to validate and to demonstrate the effectiveness of the proposed method. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 256–264, 2015     

Modelling and kinetic aspects of a BTEX contaminated air-treating biofilter

In this study, the overall performance of a biofilter was evaluated in terms of its elimination capacity by using 3-D mesh techniques. The overall results indicate that the agreement between experimental data and model predictions is excellent for benzene, toluene, ethylbenzene and o-xylene (BTEX). In this study, the maximum removal rate (r _max) values for BTEX were 0.0117, 0.0126, 0.0081 and 0.0146 g m^–3 h^–1, and the half-saturation constant (K_S ) values were calculated to be 0.269, 0.297, 0.156 and 0.394 g m^–3, respectively. For this system, the coefficients of determination (r ²) of BTEX compounds were greater than 0.97. The BTEX concentration profiles along the depth were also determined using a convection–diffusion reactor (CDR) model. The sums of squares of the errors (SSEs) of BTEX were 0.0078, 0.0059, 0.0129 and 0.0269, respectively, with r ² values greater than 0.99 for all four compounds at low concentrations.     

A Review: Tailor-made Hydrogel Structures (Classifications and Synthesis Parameters)

Hydrogels are being prepared for use in a wide variety of applications ranging from medicines, tissue engineering, superabsorbents, controlled release of drugs & fertilizers, and oil absorbers etc. This review highlights hydrogel structure and their different classifications under various heads. It also discusses various routes to obtain tailormade hydrogels by polymerizing a combination of two or more monomers with proper type of crosslinks in order to obtain desired properties in the resulting hydrogel. Novel hydrogel configurations like microgels and nanogels, slide ring gels, double network hydrogels and nanocomposite gels have also been reviewed.     

Enhanced Visible Light Photocatalytic Activity of Curcumin‐Sensitized Perovskite Bi0.5Na0.5TiO3 for Rhodamine 6G Degradation

Curcumin‐sensitized perovskite Bi_0.5Na_0.5TiO₃ (BNT) was synthesized for visible light photocatalytic decolorization of rhodamine 6G (Rh6G). Cube‐shaped perovskite BNT was synthesized by solid‐state route, and curcumin sensitization was performed using hydrothermal method. The surface sensitization of curcumin was analyzed by UV–Vis absorption spectra and FTIR. The degradation kinetics of Rh6G over Cur‐BNT were investigated and discussed through first‐order Langmuir–Hinshelwood kinetic model. The effect of catalyst dose on photocatalytic decolorization process was investigated. Photocatalysis was performed with different scavengers to investigate the role of active hole and radical species and photocatalytic degradation mechanism of Rh6G.     

Effect of ferroelectric polarization on piezo/photocatalysis in Ag nanoparticles loaded 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.1Ti0.9)O3 composites towards the degradation of organic pollutants

A 0.5(Ba_0.7Ca_0.3)TiO₃–0.5Ba(Zr_0.1Ti_0.9)O₃ (BCT-BZT) ceramic was studied for photocatalysis and piezocatalysis effects using dye degradation (methylene blue, rhodamine B, and methyl orange) and bacterial (Escherichia coli) disinfection from aqueous solution. To examine the effect of ferroelectric polarization, BCT-BZT powder was poled using the corona poling technique. Same time, BCT-BZT was converted into Ag/BCT-BZT composites as Ag induced surface plasmon resonance effect during photocatalysis. Piezocatalysis performance was assessed for dyes mineralization under ultrasonication. There was a significant impact of silver nanoparticles on the photo/piezocatalysis performance of BCT-BZT. Similarly, electric poling has also played a positive role in improving the photo/piezocatalysis in view of various dye degradation. These samples also showed effective antibacterial performance.