Optimization of Preparation Conditions to Control Structural Characteristics of Silicon Dioxide Nanostructures Prepared by Magnetron Plasma Sputtering

In this work, highly-pure silicon oxide nanostructures were prepared by a closed-field unbalanced magnetron plasma sputtering technique. These nanostructures were characterized by Fourier-transform infrared spectroscopy, UV-visible spectroscopy, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy and atomic force microscopy in order to determine the optimum preparation conditions. Minimum particle size of 20 nm was determined for the samples prepared at an inter-electrode distance of 4 cm, Ar:O₂ gas mixing ratio of 70:30, total gas pressure of 0.08 torr, discharge voltage of 2.5 kV, discharge current of 35 mA, anode temperature of 27 ^°C (room temperature) and cathode temperature of about 40 ^°C. These conditions are optimized to control the structural characteristics of such nanostructures and hence to satisfy certain requirements and purposes in spectroscopic and photonic applications of SiO₂ nanostructures.     

Effects of space velocity on methanol synthesis from Co2/Co/H2 over Cu/ZnO/Al2O3 catalyst

The space velocity had profound and complicated effects on methanol synthesis from CO₂/CO/H₂ over Cu/ZnO/Al₂O₃ at 523 K and 3.0MPa. At high space velocities, methanol yields as well as the rate of methanol production increased continuously with increasing CO₂ concentration in the feed. Below a certain space velocity, methanol yields and reaction rates showed a maximum at CO₂ concentration of 5–10%. Different coverages of surface reaction intermediates on copper appeared to be responsible for this phenomenon. The space velocity that gave the maximal rate of methanol production also depended on the feed composition. Higher space velocity yielded higher rates for CO₂/ H₂ and the opposite effect was observed for the CO/H₂ feed. For CO₂/CO/H₂ feed, an optimal space velocity existed for obtaining the maximal rate.     

Equilibrium modeling and kinetic studies on the adsorption of basic dye by a low-cost adsorbent: coconut (Cocos nucifera) bunch waste

In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 degrees C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 degrees C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.     

Point Defects in CdZnTe Crystals Grown by Different Techniques

We studied, by current deep-level transient spectroscopy (I-DLTS), point defects in CdZnTe detectors grown by different techniques. We identified 12 different traps with energy levels from 7 meV to 1.1 eV. Although the levels of most of the identified defects were independent of the crystal growth techniques, nevertheless there were some associated differences in the traps’ energies and densities.     

Changes in total phenols, total flavonoids, and antioxidant activities of common beans and pinto beans after soaking, cooking, and in vitro digestion process

Even though bean varieties are widely consumed all over the world, data related to how cooking methods and in vitro digestion affect bioactive compounds they contain and data related to bioavailability of polyphenols are limited. The aim of the present study was to investigate how some cooking methods and in vitro digestion influence antioxidant activity, total phenols (TP), and total flavonoids (TF) of widely consumed beans in Turkey. Soaking caused a significant decrease (25.61–38.63%) in the bioavailability of TP of dry common beans (CB). Soaking in cold water resulted in a significant decrease in TP bioavailability of dry pinto beans (PB). TF content was well retained in PB cooked without soaking but was not detected in CB after in vitro digestion. CB soaked in hot water and cooked with the addition of NaHCO₃ showed the greatest inhibition effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (p<0.05). In vitro digestion caused increase in the antioxidant activity of both CB and PB.     

Catalytic fluorination of HCFC-133a (1,1,1-trifluoro-2-chloroethane)

Catalytic fluorination of HCFC-133a was performed over metal oxide catalysts. Chromium oxide showed the best catalytic activity among several metal oxides tested. An increase in the crystallinity with decreased surface area resulted in a decrease of catalytic activity for the fluorination reaction. Active phase of chromia is Cr-O-F-OH having a proper ratio of O/F and a high hydroxyl content. The hydroxyl content on the catalyst is strongly dependent on support material. The selectivity to HFC-134a is independent of the O/F ratio on the Cr surface.     

Postponement growth and antioxidative response of Brassica nigra on CuO and ZnO nanoparticles exposure under soil conditions

Due to unique physiochemical properties, nanoparticles (NPs) have acquired substantial attention in the field of research. However, threats of ecotoxicity and phytotoxicity have limited their biological applications. In this study in vivo experiments were performed to determine the effect of CuO (12.5, 25 and 50 mg/kg) and ZnO (200, 400 and 600 mg/kg) NPs on growth, and antioxidant activities of Brassica nigra. The results showed that CuO NPs did not affect the seed germination while presence of ZnO NPs in the soil generated an inhibitory effect. Both CuO and ZnO NPs positively influenced the growth of stem and other physiological parameters i.e. stem height increased (23%) at 50 mg/kg CuO while root length decreased (up to 44%) with an increase in the concentration of NPs. Phytochemical screening of apical, middle and basal leaves showed elevated phenolic and flavonoid contents in the range of 15.3–59 μg Gallic Acid Equivalent (GAE)/mg Dry Weight (DW) and 10–35 μg Querceitin Equivalent (QE)/mg DW, respectively, in NPs‐treated plants. Antioxidant activity was higher in CuO NPs‐treated plants as compared to ZnO and control plants. Results conclude that CuO and ZnO NPs at low concentrations can be exploited as nanofertilisers in agriculture fields.Inspec keywords: biochemistry, enzymes, renewable materials, crops, nanoparticles, soil, nanofabrication, zinc compounds, organic compounds, agricultural products, toxicology, nanobiotechnologyOther keywords: antioxidative response, ZnO nanoparticles exposure, soil conditions, unique physiochemical properties, germination, antioxidant activities, brassica nigra plant, antioxidant activity, CuO NP‐treated plants, control plants, ZnO NPs effect, mass 15.3 mug to 59.0 mug, mass 10.0 mug to 35.0 mug, CuO, ZnO     

Damage of Neuroblastoma Cell SH-SY5Y Mediated by MPP+ Inhibits Proliferation of T-Cell Leukemia Jurkat by Co-Culture System

The adaptive immune system has implications in pathology of Parkinson’s disease (PD). Research data demonstrated that the peripheral CD4⁺ T-cell population decreased in pathogenesis of PD. The effect of damaged dopaminergic neurons on peripheral T cells of PD is still unknown. In this study, we constructed a neuronal and glial cells co-culture model by using human neuroblastoma cells SH-SY5Y and gliomas cells U87. After the co-culture cells were treated with neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺) for 24 h, the conditioned media was harvested and used to cultivate T-cell leukemia Jurkat cells for another 24 h. We then analyzed the cell proliferation, cell cycle and necrosis effect of Jurkat cells. The results showed that co-culture medium of SH-SY5Y and U87 cells with MPP⁺ treatment inhibited the proliferation of Jurkat cells compared to control medium without MPP⁺, even though the same concentration of MPP⁺ had very little toxicity to the Jurkat cell. Furthermore, co-culture medium with low concentration of MPP⁺ (100 µM) arrested Jurkat cells cycle in G2/M phase through increasing cell cycle division 2 (CDC2) and CyclinB1 expression level, whereas co-culture medium with high concentration of MPP⁺ (500 µM) induced Jurkat cell necrosis through cellular swelling and membrane breakage. Our data implies that damaged dopamine neurons with glial cells can lead to the reduced number or inhibited proliferation activity of peripheral T cells.     

Transformation and intensification of tornado-like flow in a narrow channel during elongation of an oval dimple with constant area

Technical Physics Letters - Reynolds averaged Navier–Stokes equations closed using the Menter shear-stress-transfer model have been numerically solved on multiblock intersecting structured...     

Highly Efficient,Solution‐Processed,Single‐Layer,Electrophosphorescent Diodes and the Effect of Molecular Dipole Moment

A new family of highly soluble electrophosphorescent dopants based on a series of tris‐cyclometalated iridium(III) complexes (1–4) of 2‐(carbazol‐3‐yl)‐4/5‐R‐pyridine ligands with varying molecular dipole strengths have been synthesized. Highly efficient, solution‐processed, single‐layer, electrophosphorescent diodes utilizing these complexes have been prepared and characterized. The high triplet energy poly(9‐vinylcarbazole) PVK is used as a host polymer doped with 2‐(4‐biphenylyl)‐5‐(4‐tert‐butyl‐phenyl)‐1,3,4‐oxadiazole (PBD) for electron transport. Devices with a current efficiency of 40 cd A^?1 corresponding to an EQE of 12% can thus be achieved. The effect of the type and position of the substituent (electron‐withdrawing group (CF₃) and electron‐donating group (OMe)) on the molecular dipole moment of the complexes has been investigated. A correlation between the absorption strength of the singlet metal‐to‐ligand charge‐transfer (¹MLCT) transition and the luminance spectral red shift as a function of solvent polarity is observed. The strength of the transition dipole moments for complexes 1–4 has also been obtained from TD‐DFT computations, and is found to be consistent with the observed molecular dipole moments of these complexes. The relatively long lifetime of the excitons of the phosphorescence (microseconds) compared to the charge‐carrier scattering time (less than nanoseconds), allows the transition dipole moment to be considered as a “quasi permanent dipole”. Therefore, the carrier mobility is sufficiently affected by the long‐lived transition dipole moments of the phosphorescent molecules, which are randomly oriented in the medium. The dopant dipoles cause positional and energetic disorder because of the locally modified polarization energy. Furthermore, the electron‐withdrawing group CF₃ induces strong carrier dispersion that enhances the electron mobility. Therefore, the strong transition dipole moment in complexes 3 and 4 perturbs both electron and hole mobilities, yielding a reduction in exciton formation and an increase in the device dark current, thereby decreasing the device efficiency.