Photocatalytic degradation of dimethyl sulphoxide by CdS/TiO2 core/shell catalyst: A novel measurement method

In the present research, the photocatalytic degradation of dimethyl sulphoxide (DMSO) by means of CdS/TiO₂ core/shell nanocomposite was investigated and modelled for the direct measurement of degradation rate. Instead of common measurement methods, liquid freezing point measurement was used in order to determine the rate of DMSO decomposition. To model the photocatalytic behaviour, two empirical-statistical equations based on photocatalytic retention time, amount of catalyst and pollutant were introduced. The effect of parameters such as retention time, amount of catalyst and pollutant were studied by statistical methods. The design of experiments, acquisition and optimization of statistical models was performed by response surface methodology (RSM) through central composite design (CCD). The rates of disappearance fitted the Langmuir-Hinshelwood kinetics model and the parameter k was determined to be up to 0.0105 per minute for a low concentration and 0.0073 per minute for a high concentration of DMSO. In addition, more than 85% degradation of 1% DMSO was attained by 8% catalyst in 150 minutes. Finally, the accuracy and consistency of the statistical models was verified by the HPLC method and ~ ± 2.7% difference was observed. The other results indicate that the CdS/TiO₂ nano photocatalyst can efficiently remove dimethyl sulphoxide from wastewater under visible light irradiation.     

CH4 reforming with CO2 for syngas production over nickel catalysts supported on mesoporous nanostructured γ-Al2O3

Nanostructured γ-Al₂O₃ with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, BET, TPR, TPH, SEM and TPO techniques. The BET analysis showed a high surface area of 204m²g^?1 and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The results revealed that an increase in nickel loading from 5 to 15 wt% decreased the surface area of catalyst from 182 to 160 m²g^?1. In addition, the catalytic results showed an increase in methane conversion with increase in nickel content. TPO analysis revealed that the coke deposition increased with increasing in nickel loading, and the catalyst with 15 wt% of nickel showed the highest degree of carbon formation. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Increasing CO₂/CH₄ ratio increased the methane conversion. The BET analysis of spent catalysts indicated that the mesoporous structure of catalysts still remained after reaction.     

A new route to mass production of metal hydroxide/oxide hydroxide nanoparticles

Aluminum hydroxide/oxide hydroxide nanofibers were self-assembled by hydration of highly activated aluminum powder using no surfactants or templates. The activation was performed by milling aluminum powder with sodium chloride as nano-miller. Transmission electron microscopy images and X-ray diffraction patterns confirm that this method leads to smaller size of aluminum particles (less than 50 nm) and increases the lattice strain. These factors provide conditions under which hydration procedure proceeds until it reaches the core of aluminum particles. The synthesized powder consists of nanofibers with thickness less then 10 nm and average length of 120 nm and specific surface area of 309 m² g⁻¹. The process is convenient, highly efficient and capable to be implemented in mass production. It may be extended to produce hydroxide/oxide hydroxide nanopowders of other metals, as well.     

Rate of heat transfer in polypropylene tubes in solar water heaters

A heat transfer rate was determined for polypropylene tubes in solar water heaters for the Reynolds number range 800-5600. Experiments were conducted in ambient temperatures of 34 to 37 °C. Data were correlated in the form of Nusselt numbers as: Nu=0.0015 Re^0.75Pr^1/3 with correlation coefficient of 0.95. Such data can be used to predict heat transfer rates in a polypropylene solar heater in Tehran where the experiments were performed. An application of the results is shown in an example.     

The Influence of Resonance Helical Field on the Z eff and Impurity Radiation in IR-T1 Tokamak

The influence of resonant helical field, RHF, on effective ion charge, Z _eff, and impurity radiations on IR-T1 tokamak discharges was studied. The theoretical calculation of Z _eff with RHF indicated that the Z _eff decreased. To observe the effects of reduced Z _eff on impurity radiation, two important parts of plasma were investigated, equilibrium region of plasma and disruptive plasma. The results obtained from previous experiments on equilibrium plasma showed the increased radiation of impurities, in comparison with preceding and next regions, whereas the new results indicate that the impurities radiation decreases remarkably in disruptive part of plasma.     

A low-power and robust quaternary SRAM cell for nanoelectronics

This paper presents an efficient and low-power quaternary static random-access memory (SRAM) cell based on a new quaternary inverter. For implementation, carbon nanotube field-effect transistors (CNTFETs) are used. Stacked CNTFETs are appropriately used in the proposed design to achieve a considerably low static power dissipation. The proposed SRAM has a more significant static noise margin due to its single quaternary digit line, and it is appropriate for MVL SRAM design as there are more than two stable states. The simulation results using Synopsys HSPICE with 32 nm Stanford comprehensive CNTFET model demonstrate the correct and robust operation of the proposed designs even in the presence of major process variations. In addition, the proposed SRAM cell is applied in a 4?×?4 SRAM array structure to demonstrate the efficiency of the proposed SRAM. The results indicate that the proposed design significantly lowers the power consumption and provides comparable static noise margins compared to the other state-of-the-art CNTFET-based circuits.

     

Acidic Derivatives of Melamine as Template in Copolymerization of Aniline and Metanilic Acid

In this paper, new polymer composites were synthesized by template copolymerization of aniline and metanilic acid in the presence of prepared melamine triacetic acid and poly(melamine-co-citric acid) as polyacids and dopants. The properties of the poly(aniline-co-metanilic acid) composites were studied by Fourier transform infrared, X-ray diffraction, scanning electron microscope, CV, and differential scanning calorimeter analysis. The four-point probe technique was used for evaluating the electrical conductivity of the composites. The scanning electron micrographs disclosed that the products had the morphology with agglomerated distorted spherical shapes with the average size of 40–50?nm. Also, the solubility of the composites had been improved notably in organic solvents.     

High-Stability Platinum Nano-Electrocatalyst Synthesized by Cyclic Voltammetry for Oxygen Reduction Reaction

Cyclic voltammetry as a simple electrochemical deposition method was developed in order to prepare a platinum nano-electrocatalyst for oxygen reduction reaction (ORR) in low-temperature fuel cell systems. The morphology of the prepared platinum was evaluated by scanning electron microscopy and energy dispersive x-ray analysis. The effects of platinum concentration in electrodeposition solution and scan numbers of cyclic voltammetry (scan rate: 50 m V s^?1, between 1.489 and ??0.311 versus reversible hydrogen electrode) on the performance of prepared electrocatalysts for ORR were studied. The fabricated electrodes were evaluated by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The results revealed that the optimum conditions for the preparation of electrocatalysts were 2E?3 M H₂PtCl₆ and 30 scan numbers. The optimized electrode showed high stability after 1200 cycles.     

A quick method to fabricate large glass micromodel networks

Microsystem Technologies - The study of multi-phase fluid flow in microfluidic devices provides an opportunity for researchers to characterize effective factors and mechanisms in microscale. The...