Numerical analysis and experimental investigation into the performance of a wire-on-tube condenser of a retrofitted refrigerator

The present paper discusses (a) the analysis of a wire-on-tube condenser under varying operating conditions of free convection using FEM, and (b) experimental verification of the performance of two wire-on-tube condensers in a retrofitted domestic refrigerator using refrigerant R-134a. The study is motivated by the desire to investigate if the wire-on-tube condensers used in R-12 based refrigerators could be used in a modified refrigerator using R-134a refrigerant. Experiments were conducted in a climate chamber under controlled and varying ambient temperatures and mass flow rates to determine the locations where phase change occurs and the degree of subcooling achieved. In terms of initial and final phase change point locations the predicted results agree with the experimental results to within ±10%. The analysis and the experiments also lead to the information about the adequacy of the number of tubes for complete condensation of the refrigerant vapour under given operating conditions. The methodology can be used as a design tool for the design of wire-on-tube condenser of a small refrigerator as well as the suitability of specific decommissioned condensers for use in a retrofitted refrigerator. It also indicates that R-12 based refrigerators using wire-on-tube condensers retrofitted with R-134a compressor and refrigerant deserve and warrant further studies for adoption.     

An extended element free Galerkin method for fracture analysis of functionally graded materials

An extended element free Galerkin method (XEFGM) has been adopted for fracture analysis of functionally graded materials (FGMs). Orthotropic enrichments functions are used along with the sub-triangle technique for enhancing the Gauss quadrature accuracy near the crack, and the incompatible interaction integral method is employed to calculate the stress intensity factors. Numerical simulations have proved that XEFGM provides more accurate results by less number of nodes (DOFs) in comparison with the unenriched EFGM and other conventional methods for several FGM problems with different crack locations and loadings. The results have been compared with the reference results, showing the reliability, stability, and efficiency of present XEFGM.

Received 9 June 2014 Accepted 17 September 2014.     

Bio‐inspired synthesis of silver nanoparticles from leaf extracts of Cleistanthus collinus (Roxb.): its potential antibacterial and anticancer activities

In this investigation, the biological synthesis method was adopted to synthesise silver nanoparticles (AgNPs) by using the leaf extracts of Cleistanthus collinus (C. collinus). This plant has traditionally been used to remove the harmful pest from the agriculture field. Leaf extract of C. collinus was used as bioreductant on the precursor solvent of AgNO₃. The synthesised AgNPs were characterised by spectroscopic method such as UV–vis spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, dynamic light scattering and microscopic method by field‐emission scanning electron microscopy analysis. The AgNPs were studied for both antibacterial and antifungal activities and found to exhibit potential antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. The anticancer activity of AgNPs was screened against A‐431 osteosarcoma cell line by [3‐(4, 5‐dimetheylthiazol‐2)‐2, 5 diphenyl tetrazolium bromide] assay and the IC₅₀ value was found to be 91.05 ± 1.53 μg/ml. This trend of eco‐friendly stable synthesis of AgNPs could prove a better substitute for the chemical methods and offer greater opportunity to use these nanosilvers in agricultural and biomedical sectors.Inspec keywords: bio‐inspired materials, silver, nanoparticles, nanomedicine, antibacterial activity, cancer, biomedical materials, microorganisms, nanofabrication, attenuated total reflection, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, light scattering, scanning electron microscopy, field emission electron microscopy, cellular biophysicsOther keywords: bio‐inspired synthesis, silver nanoparticles, Cleistanthus collinus, antibacterial activity, anticancer activity, leaf extracts, biological synthesis method, bioreductant, precursor solvent, UV‐visible spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, dynamic light scattering, field‐emission scanning electron microscopy, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, A‐431 osteosarcoma cell line, 3‐(4, 5‐dimetheylthiazol‐2)‐2,5 diphenyl tetrazolium bromide assay, eco‐friendly stable synthesis, Ag     

Design,simulation and analysis of micro electro‐mechanical system microneedle for micropump in drug delivery systems

This article reports on the mechanical strength analysis and flow characteristics of square tip and circular tip microneedles by employing highly potent drugs that are given in extremely little quantity (microlitres) using MEMS technology, which proves to be a significant component of micropump in the application of Bio‐MEMS. These microneedles are well suitable for a MEMS‐based micropump in the drug delivery systems. It is an essential part of the micropump through which the drug is released into the patient’s body. The proposed microneedles can withstand a stress of 23 MPa and 20 KPa. An extensive investigation on selection of material for the microneedle is carried out to meet the requirements of the biocompatibility and high yield, as well as tensile strength. As mighty drugs such as vasopressin, atropine and digoxin are administered in large quantities, the microneedle is designed so as to deliver 800 µl of drug, with each microneedle delivering 90 µl. in a 3 3 array. 3 × 3 array releasing 90 µl.     

Microscopic techniques for characterization and authentication of oil-yielding seeds

Investigation of alternative energy sources is need of current time due to growing power crisis and associated environmental issues. Biodiesel is considered as sustainable power source and promising alternative to fossil fuels. Therefore, our current investigation aimed to identify micromorphological characters of 10 novel nonedible oil-yielding seeds through scanning electron microscopy. It was revealed from light microscopic study that there is variation in seed size from 3 to 15 mm in length and 2 to 11 mm in width. Likewise, a huge variation in color was observed such as light green, greenish yellow, blackish brown, and various shades of brown. Presence and absence of Hilum was observed, and compression of seeds varied from depressed, lateral, and dorsoventral. Seed's shape differs from ovate, clavate, triangular ovate, cuneiform, ovoid, and elliptical shape. Seed oil content fall in range of 18–58% (wt/wt). Free fatty acid content of the seeds varies from 0.3 to 3.1 mg KOH/g. Ultrastructure of seeds exhibited huge variation in shape, size, periclinal wall, anticlinal wall, and surface ornamentation. Nonedible seeds varied in wall structure from angular, wavy, dentate entire, irregular, puzzled, elongated, even, and polygonal. The periclinal wall arrangements show alteration from flat, looped, raised, depressed, lofty, even, pentagonal, polygonal, and undulate seed margins. Outcomes of this investigation recommended that scanning electron microscopy could act as a helpful tool in disclosing the hidden micromorphological characters among nonedible oil-yielding seeds and subsequently helping in correct, authentic seed identification and classification as potential feedstock for biodiesel.     

An exploration of 3-methoxypropionitrile chemical sensor based on layered hexagonal NiCo2O4 nanoplates as electrode material

Binary metal oxide, nickel-cobalt oxide (NiCo₂O₄), was hydrothermally synthesized for the successful utilization as electrochemical electrode in chemical sensor. Benefited from the large surface area, binary NiCo₂O₄ stacked hexagonal nanoplates (HNPs) based electrode was utilized for the electrochemical sensing application towards teratogenic chemical i.e. 3-methoxypropionitrile (3-MPN). The sensing results displayed a reproducible sensitivity of ~605 μAμM^?1cm^?2, detection limit of ~11.8 μM with the correlation coefficient (R) of ~0.99502 and good linearity from ~10 μM to ~100 μM. Stability and repeatability of binary NiCo₂O₄ stacked HNPs based electrode was investigated with satisfactory results. Our synthesized binary NiCo₂O₄ stacked HNPs based electrode is promising for sensor applications and thus, enlightens the possibility of synthesizing other binary oxide materials.     

Relating research growth,authorship patterns and publishing outlets: a bibliometric study of LIS articles produced by Pakistani authors

Scientometrics - Research is a key element of any profession and an analysis of published research enables professional communities to understand the dynamics of growth in a profession and its...     

Attenuating noise from computed tomography medical images using a coefficients‐driven total variation denoising algorithm

The aim of image denoising is to recover a visually accepted image from its noisy observation with as much detail as possible. The noise exists in computed tomography images due to hardware errors, software faults and/or low radiation dose. Because of noise, the analysis and extraction of accurate medical information is a challenging task for specialists. Therefore, a novel modification on the total variational denoising algorithm is proposed in this article to attenuate the noise from CT images and provide a better visual quality. The newly developed algorithm can properly detect noise from the other image components using four new noise distinguishing coefficients and reduce it using a novel minimization function. Moreover, the proposed algorithm has a fast computation speed, a simple structure, a relatively low computational cost and preserves the small image details while reducing the noise efficiently. Evaluating the performance of the proposed algorithm is achieved through the use of synthetic and real noisy images. Likewise, the synthetic images are appraised by three advanced accuracy methods –Gradient Magnitude Similarity Deviation (GMSD), Structural Similarity (SSIM) and Weighted Signal‐to‐Noise Ratio (WSNR). The empirical results exhibited significant improvement not only in noise reduction but also in preserving the minor image details. Finally, the proposed algorithm provided satisfying results that outperformed all the comparative methods.     

Coplanar waveguide‐fed electrically small dual‐polarized short‐ended zeroth‐order resonating antenna using Ω‐shaped capacitor and single‐split ring resonator for GPS/WiMAX/WLAN/C‐band applications

This work explains the design and analysis of a triple‐band electrically small (ka = 0.56 < 1) zeroth‐order resonating (ZOR) antenna with wideband circular polarization (CP) characteristics. The antenna compactness is obtained due to ZOR frequency of composite right/left‐handed (CRLH) transmission line (TL) and wideband CP radiation are achieved due to the introduction of single‐split ring resonator and asymmetric coplanar waveguide fed ground plane. The proposed antenna obtains an overall electrical size including the ground plane of 0.124 λ₀ × 0.131 λ₀ × 0.005 λ₀ at 1.58 GHz and physical dimension of 23.7 × 25 × 1 mm³ are achieved. The antenna provides a size reduction of 44.95% compared to a conventional monopole antenna. The novelty behind the ohm‐shaped capacitor is the generation of extra miniaturization with better antenna compactness. The antenna provides dual‐polarized radiation pattern with linear polarization radiation at 1.58 and 3.54 GHz, wideband CP radiation at 5.8 GHz. The antenna measured results shows good impedance bandwidth of 5%, 6.21%, and 57.5% for the three bands centered at 1.58, 3.54, and 5.8 GHz with a wider axial ratio bandwidth (ARBW) of 25.47% is obtained in the third band. The antenna provides a higher level of compactness, wider ARBW, good radiation efficiency, and wider S₁₁ bandwidth. Hence, the proposed antenna is suitable for use in GPS L1 band (1.565‐1.585 GHz), WiMAX 3.5 GHz (3.4‐3.8 GHz) GHz, WLAN 5.2/5.8 GHz (5.15‐5.825 GHz), and C‐band (4‐8 GHz) wireless application systems.