Numerical Analysis of Artificial Electron Heating Effects on Polar Mesospheric Winter Echoes

In this paper, an analytical model is used to analyze the modulated polar mesospheric winter echoes (PMWE). The winter parameters were introduced to simulate the effects of different parameters during the artificial electron heating of PMWE. The important role of the charged dust particle in the creation of PMWE is confirmed again. It is found that during the heating of PMWE, the increases of the dust size, dust charge, electron temperature, initial electron density, and ion-neutral collision frequency cause the increase of the electron density irregularity, and hence the PMWE strength. However, with increasing the dust density, the electron density irregularity and the PMWE strength decrease.     

Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

In this work, a novel compact wideband reconfigurable circularly polarised (CP) dielectric resonator antenna (DRA) is presented. The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed. This arrangement of feed-line helps to generate two orthogonal modes inside the DR, which makes the design circularly polarised. A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches. These switches located at the left and right of the micro-strip line helps in performing two switching operations. The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications. For the switching operation I, the achieved impedance bandwidth is 24% while axial ratio bandwidth (ARBW) is 42%. For this switching state, the design has 100% CP performance. Similarly, the switching operation II achieves 60% impedance bandwidth and 58.88% ARBW with 76.36% CP performance. The proposed design has a maximum measured gain of 3.4 dBi and 93% radiation efficiency. The proposed design is novel in terms of compactness and performance parameters. The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.     

Compositional and thermal characterization of genuine and randomized lard: A comparative study

Composition and thermal characterization of genuine and randomized lard were investigated comparatively in an attempt to find common merits that assess lard detection. The investigation included compositional and positional distribution of fatty acids, triacylglycerol profiling by gas chromatography (GC) and reversed-phase high-performance liquid chromatography (RP-HPLC), as well as thermal behavior by differential scanning calorimetry (DSC) of both samples. Individual and total saturated and unsaturated fatty acid composition in total fats of both genuine and randomized lard were identical. On the other hand, the results of pancreatic lipolysis/GC analysis showed that the average percent palmitic acid [PAEF(%)] and myristic acid [MAEF(%)] enrichment factors of genuine (280 and 270) and randomized lard (110 and 98) were quite different. Thus, application of PAEF to detect randomized lard is of no value. However, normalization of fatty acid distribution by randomization in 2-monoacylglycerols made the individual and total saturated and unsaturated fatty acids almost identical to that of total fat and neutral triacylglycerols (TG) of lard. TG compositional analysis by GC revealed that both genuine and randomized lard had six dominant TG (C_46′C_48′C_50′C_52′C_54′ and C₅₆) with quite different concentrations. TG with C₅₂ represent the major constituent of genuine and randomized lard. TG profiling of samples was also carried out by RP-HPLC with a refractive index detector. The same peaks were eluted in both samples, but the area % of major peaks changed due to randomization. 2-Palmitooleostearin (SPO) was found in high proportion in lard. However, the ratios of SPO to 2-palmitooleolinolein of both genuine and randomized lard are close (0.6±0.05) and significantly distinguishable from that of beef (4.24), mutton (6.17), chicken (0.21), and turkey (0.14) fats. The DSC thermogram and thermodynamics of phase transitions of both samples were quite different and do not reveal common characteristic(s) that could be used for immediate detection of lard substances in fat admixtures.     

Removal characteristics of chromium by activated carbon/CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> magnetic composite and <Emphasis Type="Italic">Phoenix dactylifera</Emphasis> stone carbon

Activated carbon (AC) was synthesized from Phoenix dactylifera stones and then modified by CoFe₂O₄ magnetic nanocomposite for use as a Cr(VI) adsorbent. Both AC/CoFe₂O₄ composite and AC were fully characterized by FTIR, SEM, XRD, TEM, TGA, and VSM techniques. Based on the surface analyses, the addition of CoFe₂O₄ nanoparticles had a significant effect on the thermal stability and crystalline structure of AC. Factors affecting chromium removal efficiency like pH, dosage, contact time, temperature, and initial Cr(VI) concentration were investigated. The best pH was found 2 and 3 for Cr adsorption by AC and AC/CoFe₂O₄ composite, respectively. The presence of ion sulfate had a greater effect on the chromium sorption efficiency than nitrate and chlorine ions. The results illustrated that both adsorbents can be used up to seven times to adsorb chromium. The adsorption process was examined by three isothermal models, and Freundlich was chosen as the best one. The experimental data were well fitted by pseudo-second-order kinetic model. The half-life (t_1/2) of hexavalent chromium using AC and AC/CoFe₂O₄ magnetic composite was obtained as 5.18 min and 1.52 min, respectively. Cr(VI) adsorption by AC and AC/CoFe₂O₄ magnetic composite was spontaneous and exothermic. In general, our study showed that the composition of CoFe₂O₄ magnetic nanoparticles with AC can increase the adsorption capacity of AC from 36mg/L to 70mg/L.     

Analysis of Rainfall Severity and Duration in Victoria,Australia using Non-parametric Copulas and Marginal Distributions

The analysis of joint probability distributions of rainfall characteristics such as severity and duration is important in water resources management. Deriving their distributions using standard statistical techniques are often problematical due to its complexity. Standard methods usually assume that the rainfall characteristics are independent or that their marginal distributions belong to the same family of distributions. The use of copulas based methodologies can circumvent these restrictions and are therefore increasingly popular. However, the copulas and marginal distributions that are commonly used belong to specific parametric families and their adoption could lead to spurious inferences if the underlying assumptions are violated. For this reason, we recommend a nonparametric or semiparametric approach to estimate the joint distribution of rainfall characteristics. In this paper, we introduce and compare several copula–based approaches, each involving a combination of parametric or nonparametric marginal distributions conjoined by a parametric or nonparametric copula. An empirical illustration of the different approaches using rainfall data collected from six stations in the state of Victoria, Australia, demonstrated that a nonparametric approach can often give better results than a purely parametric approach.     

Adsorption performance of amine functionalized cellulose grafted epichlorohydrin for the removal of nitrate from aqueous solutions

Cellulose grafted epichlorohydrin (Cell-g-E) copolymer was synthesized and functionalization carried out using polyethylenimine (Cell-g-E/PEI). Characterization studies using FTIR, XRD and TGA, confirmed the grafting and functionalization process. Batch adsorption reaction was carried out for removal/recovery of nitrate ions and maximum adsorption capacity was obtained at pH 4.5. Kinetic studies explained pseudo-second-order as the best fit. Isotherm studies conducted at different temperatures revealed applicability of Freundlich isotherm model. Comparative studies proved effectiveness of Cell-g-E/PEI to other reported adsorbents. The adsorption process was spontaneous and exothermic. Batch adsorption/desorption studies for over six cycles showed the repeatability and regeneration capability of the adsorbent.     

Silver nanoparticles and silver salt (AgNO3) elicits morphogenic and biochemical variations in callus cultures of sugarcane

The research work was arranged to check the role of AgNPs and silver ions on callus cells of sugarcane (Saccharum spp. cv CP‐77,400). AgNPs were synthesized chemically and characterized by UV‐Vis spectra, XRD and SEM. AgNPs and silver ions were applied in various concentrations (0, 20, 40, 60 ppm) to sugarcane calli and the induced stress was characterized by studying various morphological and biochemical parameters. AgNPs and silver ions treatments produced high levels of malondialdehyde, proline, proteins, TP and TF contents. Similarly, CAT, SOD and POX activity was also significant in both treatments. The lower concentration of AgNPs and silver ions (20 ppm) provided maximum intracellular GSH level. This work mainly showed effects of AgNPs and silver ions on sugarcane calli in terms of morphological aberrations and cell membrane damage due to severe oxidative stress and production of enhanced levels of enzymatic and non‐enzymatic antioxidants as self‐defence to tolerate oxidative stress by scavenging reactive oxygen species. These preliminary findings will provide the way to study ecotoxicity mechanism of the metal ions and NPs in medicine industry and in vitro toxicity research. Furthermore, silver ions alone and their chemically synthesised AgNPs can be used for various biomedical applications in future.Inspec keywords: nanoparticles, biomedical materials, X‐ray diffraction, scanning electron microscopy, silver, molecular biophysics, toxicology, enzymes, visible spectra, nanofabrication, ultraviolet spectra, microorganisms, nanotechnology, plant diseases, crops, agricultural safetyOther keywords: silver nanoparticles, silver salt, scanning electron microscopy, total flavonoid contents, callus cultures, sugarcane cultivation, Saccharum spp, UV‐visible spectroscopy, X‐ray diffraction analysis, malondialdehyde, proline, proteins, total phenolic content, catalase, superoxide dismutase, peroxidases activities, scavenging reactive oxygen species, biomedical applications, microbial disease resistance, AgNO₃ , Ag     

Experimental results on kinematic calibration of parallel manipulators using a partial pose measurement device

This paper presents kinematic calibration of parallel manipulators with partial pose measurements, using a device that measures a rotation of the end-effect or along with its position. The device contains a linear variable differential transformer, a biaxial inclinometer, and a rotary sensor. The device is designed in a modular fashion, and links of different lengths can be used. Two additional kinematic parameters required for the measurement device are discussed, kinematic relations are derived, and cost function is established to perform calibration with the proposed device. The study is performed for a six-degree-of-freedom fully parallel HexaSlide mechanism (HSM). Experimental results show significant improvement in the accuracy of the HSM.