Optical,FTIR and ESR Spectral Investigations of Tungsten Ions in Barium Phosphate Host Glass and Effects of Gamma Irradiation

Silicon - Tungsten oxide (0.25 – 3% WO3) doped barium phosphate glasses were prepared by the conventional melting annealing procedure. Spectroscopic FTIR infrared and ESR measurements were...     

Survival, developmental and morphogenic deficiencies of Parasarcophaga argyrostoma (Diptera: Sarcophagidae) induced by the biosynthesis inhibitor, chlorfluazuron (IKI-7899)

To evaluate the activity of benzoylphenyl urea chitin biosynthesis inhibitor chlorfluazuron (IKI-7899) against Parasarcophaga argyrostoma, seven doses were topically applied (once) onto early third (last) instar larvae, puparia, or newly formed pupa: 150, 100, 50, 10, 1.0, 0.5, and 0.25 microgram/insect. After topical treatment of last instar larvae, the highest mortality was caused by both higher doses and the lowest mortality was caused by the lowest dose. The lethal activity of IKI-7899 as pronouncedly decreased as the treatment was lately carried out (at the puparial time). IKI-7899 failed to cause cumulative mortality because no pupal or adult mortalities were observed, irrespective of the time of treatment. Treated larvae suffered the action of IKI-7899 because they had decreased weight gain. Except the lowest dose, the weight gain of larvae inversely correlated with the dose-levels. IKI-7899 prolonged not only the larval duration but also the pupal duration after topical treatment of last instar larvae with doses 50-0.25 micrograms/larva. With no exception, all doses topically applied onto puparia or newly formed pupae enhanced pupae to live longer. Topical application onto last instar larvae resulted in different degrees of reduction of pupation rate, but IKI-7899 could not affect the pupal morphogenesis after larval treatment except by its highest dose which led to 8.33% pupal deformities and 7.69% larval-pupal intermediates. The dose 100 micrograms/larva topically applied onto last instar larvae detained 7.69% of what known as "permanent larvae" which suffered the action of the compound along 16 days and eventually perished without any external feature of puparium formation. A metamorphic effect of IKI-7899 pronouncedly appeared in the adult stage. Three higher doses completely arrested the adult flies. Topical application of the compound onto prepupae did not greatly reduce the pupation rate especially at the doses 50, 10 and 1.0 micrograms/puparium. The dose 50 micrograms/puparium was only the dose halting the pupal moulting program because 7.14% of permanent prepupae remained about 12 days and then died. In respect to adult emergence, the highest dose led to zero rate and the lowest dose allowed to all pupae to emerge without malformation.     

Mining tag-clouds to improve social media recommendation

Multimedia Tools and Applications - Massive amounts of data are available on social websites, therefore finding the suitable item is a challenging issue. According to recent social statistics, we...     

Relaxation dynamic and electrical mobility for poly(methyl methacrylate)‐polyaniline composites

Composites of emeraldine form of polyaniline (PAni) and poly(methyl methacrylate) (PMMA) are prepared by emulsion polymerization method in definite ratios. The chemical structure of the samples and their morphologies have been investigated by different techniques including FTIR, UV–vis, XRD, SEM, and TGA. Enhancement in thermal stability of the obtained composites by PAni additions has been confirmed. Alpha analyzer, in frequency range 0.1 Hz to 20 MHz, was employed to investigate the molecular dynamics of the prepared samples and the accompanied electrical conductivity at temperatures ranging from 223 to 423 K. Conductivity investigations showed that mobility has the more dominant effect on the charge transportation. The dynamic peak at lower temperatures of the PMMA has high activation energy (83.8 kJ/mol). While, Maxwill‐Wagner‐Siller process due to the interfacial polarization in the composites has only 7.5 kJ/mol activation energy. This is a clear indication of the ease of the investigated dynamic. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45415.     

An Interface-Enriched eXtended Finite Element-Level Set Simulation of Solutal Melting of Additive Powder Particles during Transient Liquid Phase Bonding

A new numerical simulation model is developed by using an interface-enriched eXtended Finite Element-Level Set (XFE-LS) method to study the solute-induced melting of additive powder particles (APPs) during transient liquid phase (TLP) bonding. The robust model captures rapidly occurring concurrent interfacial events at multiple propagating liquid-solid interfaces to simulate the melting behavior. In contrast to the critical assumption in analytical models, numerical calculations show that solute-transport into the APPs during the equilibration of the liquid composition is a significant factor that affects the APPs melting behavior. Also, the study shows that the solute-transport dependence of extent of APPs melting is influenced by the kinetics of solid-state solute diffusion within the particles. The understanding generated by the numerical analysis has resulted in the use of interlayer powder mixture that contains base-alloy APPs to produce single crystal TLP joint that has matching crystallographic orientations with single crystal substrate material, at a substantially reduced processing time, which has been previously considered unfeasible.     

Performance analysis of high-concentrated multi-junction solar cells in hot climate

Multi-junction concentrator solar cells are a promising technology as they can fulfill the increasing energy demand with renewable sources. Focusing sunlight upon the aperture of multi-junction photovoltaic (PV) cells can generate much greater power densities than conventional PV cells. So, concentrated PV multi-junction solar cells offer a promising way towards achieving minimum cost per kilowatt-hour. However, these cells have many aspects that must be fixed to be feasible for large-scale energy generation. In this work, a model is developed to analyze the impact of various atmospheric factors on concentrator PV performance. A single-diode equivalent circuit model is developed to examine multi-junction cells performance in hot weather conditions, considering the impacts of both temperature and concentration ratio. The impacts of spectral variations of irradiance on annual performance of various high-concentrated photovoltaic (HCPV) panels are examined, adapting spectra simulations using the SMARTS model. Also, the diode shunt resistance neglected in the existing models is considered in the present model. The present results are efficiently validated against measurements from published data to within 2% accuracy. Present predictions show that the single-diode model considering the shunt resistance gives accurate and reliable results. Also, aerosol optical depth (AOD) and air mass are most important atmospheric parameters having a significant impact on HCPV cell performance. In addition, the electrical efficiency (η) is noticed to increase with concentration to a certain concentration degree after which it decreases. Finally, based on the model predictions, let us conclude that the present model could be adapted properly to examine HCPV cells' performance over a broad range of operating conditions.     

Evaluation of the Suitability of Agriglasses Containing ZnO for Plant Fertilization

Six different samples from borosilicate and phosphate glassy systems have been synthesized. Glass batches were prepared from chemically pure materials and melted in platinum or porcelain crucibles and at temperatures in the range 1,000–1,450 °C for 2-3 h until homogeneity was reached. The prepared specimens were annealed at the appropriate temperatures of 380 or 520 °C for the phosphate and borosilicate glasses, respectively. Samples of 2 mm dimensions were tested for dissolution behavior in 2% citric acid solution for 1, 2, 3, and 4 weeks and the released phosphorous and potassium ions (macroelements) and zinc ions (microelement) were measured. Also, Infrared (IR) absorption spectra of the samples were measured before and after immersion in the leaching solution. The experimental results indicate that the release of the macroelements and microelements depends primarily on the composition of the agriglass and the percent of constituent ions and the released ions vary slightly from 1 week to 4 weeks. The IR spectra show characteristic IR absorption bands due to vibrations of collective silicate, phosphate, and borate groups, depending on the agriglass composition and the chains or units seem to be interconnected with each other within the glass network. The interpretation of the dissolution behavior is based on a suggested mechanism for the release of the easily soluble components from the glass specimens. The IR absorption spectra support and confirm the proposed behaviour for the corrosion mechanism.     

Optimum groundwater locations in the northern United Arab Emirates

Due to the increase in urban and agricultural activities in arid regions, the exploration of new locations of possible groundwater discharge and accumulation is required to augment the limited water resources. In order to locate such discharge areas, it is necessary first to identify zones of high recharge potentials. In such an arid region, like the northern United Arab Emirates (UAE), one of the ways to predict areas of potential groundwater recharge is by understanding the hydrological response of its drainage basins to rainfall events. Due to the scarcity of basic hydrological data, a hydrological model driven mainly by information on the physiographic characteristics, drainage network properties (generated from DEM), and surface cover distribution (generated from satellite images) was used to comprehend the dynamics of surface runoff through hydrographs, and hence water loss in the study area. Results show that the northern UAE is drained by 48 drainage basins emerging from the Oman Mountains. Two‐thirds of these basins drain easterly toward the Gulf of Oman, and one‐third drain westerly toward the Arabian Gulf. These basins are found to be structurally controlled by three major fault trends, which are the NE trend (Dibba zone), NW trend (Ham Zone), and WNW trend (Hatta zone).

The hydrological response of a basin is correlated with its morphological characteristics. Based on these characteristics, and through the application of a cluster analysis, it was feasible to classify the largest basins in the region into four groundwater potentiality groups in accordance with the magnitude of their peak discharges. From this study, it became evident that the downstream area of the two major basins of Ar‐Rafiah and Limhah, and their vicinities are the most probable sites for groundwater accumulation. The drainage systems of these two basins, especially those controlled by major fault lines, play a vital role in transmitting surface–subsurface rainwater from the Oman Mountains, the recharge zone, into the western desert plain, the discharge zone, where freshwater accumulates underground. The study also revealed that a large volume of groundwater is dissipated into the sea along the eastern coast. A detailed examination of MODIS thermal data supports this by revealing cool surface anomalies issuing from the mountain range toward both the western desert plain and the Gulf of Oman following major rainfall events. Thus, the technique used facilitates the prediction of new locations of optimum groundwater resources in the northern UAE. Such a technique could be adopted, with appropriate modifications, elsewhere in arid regions, where groundwater is restricted and subject to greater complexity.     

Simultaneous determination of trace aluminum (III), copper (II) and cadmium (II) in water samples by square-wave adsorptive cathodic stripping voltammetry in the presence of oxine

A validated adsorptive cathodic stripping voltammetry method is described for simultaneous determination of Al(III), Cu(II) and Cd(II) in water samples. In acetate buffer (pH 5) containing 10 μM oxine, these metal ions were determined as oxine complexes following adsorptive accumulation onto the HMDE at −0.05 V versus Ag/AgCl/KCl_s. The best signal to noise ratio was obtained using a square wave of scan increment 10 mV, frequency 120 Hz, and pulse-amplitude 25 mV. Limits of detection as low as 0.020 μg L⁻¹ Al(III), 0.012 μg L⁻¹ Cu(II) and 0.028 μg L⁻¹ Cd(II) were achieved. Interference due to various cations (K(I), Na(I), Mg(II), Ca(II), Mn(II), Fe(III), Bi(III), Sb(III), Se(IV), Pb(II), Zn(II), Ni(II), Co(II)), anions (Cl⁻, NO³⁻, SO₄ ²⁻, PO₄ ³⁻) and ascorbic acid was minimal as the measured signals change by 4% at the maximum. The stripping voltammetry method was successfully applied for simultaneous determination of Al(III), Cu(II) and Cd(II) in tap and natural bottled water samples.     

Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm) and the smallest pores (0.4–1.7 nm). The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give E_a and ΔS¹ values compatible with the characterization data of the catalysts.