Phytochemical fabrication,characterization, and antioxidant application of copper and cobalt oxides nanoparticles using <Emphasis Type="Italic">Sesbania sesban</Emphasis> plant

In this work, an ecofriendly and economic strategy for synthesize of CuO and Co₃O₄ were developed using extracted Sesbania sesban solution (ESS) as a reducing and stabilizing agent, and bioreactor. These novel nano metal oxides (NMOs) were characterized by high-resolution-transmission electron microscopy (TEM), EDAX thermo gravimetric analysis and X-ray diffraction (XRD). Morphology and size of them were investigated by TEM and the average sizes of for spherical CuO and Co₃O₄ nanoparticles are 20–40 and 15–30 nm, respectively. The XRD and EDAX confirmed the high purity for NMOs. The thermal behaviors of the NMOs exhibited good crystallographic stability within the investigated temperature range. The antioxidant and antibacterial activities of NMOs were investigated and compared to manganese(III) meso-tetraphenylporphyrin complex/Ag nanocomposite (Ag/P nanocomposite) synthesizing by ESS. The results obtained from this work showed that copper(II) oxide, cobalt oxide nanoparticles, and Ag/P nanocomposite have DPPH scavenging activity. On the other hand, NMOs have no antibacterial activity against Gram-negative bacterial strains. Cobalt oxide nanoparticles have antibacterial activity against Staphylococcus aureus, while Ag/P nanocomposite showed the antibacterial activities against both Gram-negative and Gram-positive bacterial strains.     

Non-isothermal crystallization of NaX nanocrystals/poly (vinyl alcohol) nanocomposite

Journal of Thermal Analysis and Calorimetry - This paper reports the successful synthesis of NaX nanocrystals using an organic, additive-free hydrothermal approach. Then, solution casting was used...     

Syntheses of 1-substituted 1,2,4-triazoles,imidazoles and benzimidazoles

Substituted 2-phenethyl-1,2,4-triazoles, 1-phenethylimidazoles 3 and 1-phenethylbenzimidazoles 5 were synthesized from the reaction of compound 8 with tri-n-butyltin hydride in good yield. The reaction of substituted-2-phenethyl halide with 1H-1,2,4-triazoles, imidazoles and benzimidazoles gave a low yield. The yield was increased by the use of substituted-2-phenethyl p-toluensulfonate.     

On the discontinuous Galerkin computation of N‐waves focusing

Sonic boom focusing phenomenon can be predicted using the solution to the nonlinear Tricomi equation which is a hybrid (hyperbolic‐elliptic) second‐order partial differential equation. In this paper, the hyperbolic conservation law form is derived, which is valid in the entire domain. In this manner, the presence of two regions where the equation behaves differently (hyperbolic in the upper and elliptic in the lower half‐plane) is avoided. On the upper boundary, a new mixed boundary condition for the acoustic pressure is employed. The discretization is carried out using a discontinuous Galerkin (DG) method combined with a Runge–Kutta total‐variation diminishing scheme. The results show the accuracy of DG methods to solve problems involving sharp gradients and discontinuities. Comparisons with analytical results for the linear case, and other numerical results using classical explicit and compact finite difference schemes and weighted essentially non‐oscillatory schemes are included. Copyright © 2010 John Wiley & Sons, Ltd.     

Two‐dimensional modeling for stability analysis of two‐phase stratified flow

The effect of wavelength and relative velocity on the disturbed interface of two‐phase stratified regime is modeled and discussed. To analyze the stability, a small perturbation is imposed on the interface. Growth or decline of the disturbed wave, relative velocity, and surface tension with respect to time will be discussed numerically. Newly developed scheme applied to a two‐dimensional flow field and the governing Navier–Stokes equations in laminar regime are solved. Finite volume method together with non‐staggered curvilinear grid is a very effective approach to capture interface shape with time. Because of the interface shape, for any time advancement, a new grid is performed separately on each stratified field, liquid, and gas regime. The results are compared with the analytical characteristics method and one‐dimensional modeling. This comparison shows that solving the momentum equation including viscosity term leads to physically more realistic results. In addition, the newly developed method is capable of predicting two‐phase stratified flow behavior more precisely than one‐dimensional modeling. It was perceived that the surface tension has an inevitable role in dissipation of interface instability and convergence of the two‐phase flow model. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of Iridium Oxide Nanotubes by Electrodeposition into Polycarbonate Template: Fabrication of Chromium(III) and Arsenic(III) Electrochemical Sensor

For the first time iridium oxide (IrO₂) nanotubes are synthesized by electrodeposition in a polycarbonate (PC) template. Potential cycling (90 cycles) between 0.0 and 0.9 V is used for the preparation of IrO_x nanotubes onto the PC template with a pore diameter of 100 nm. Field‐emission scanning electron microscopy (FESEM) images show, that IrO₂ nanotubes with uniform diameters of 110±10 nm and an estimated length of 1–3 µm are formed. The electrochemical properties and the electrocatalytic activity of a glassy carbon‐IrO_x nanotube modified electrode toward Cr³⁺ and As³⁺ oxidation are investigated. Finally, the modified electrode is used for micromolar detection of the proposed analytes using differential pulse voltammetry.     

An ultra-small heterostructure wavelength division multiplexer (WDM) with the ability to select two wavelengths from the s-band

In this article, a photonic crystal channel drop filter (CDF) based on \(2\times 3\) ring resonators is presented. At first, the effects of changing the radius of lattice rods and the lattice dielectric constant on the dropping efficiency of a 3-port CDF with one resonator are investigated. Then by developing this base structure, a new 4-port heterostructure CDF composed of two regions with rods made of silicone and germanium is presented, which can operate in the ‘S’ band of the communication window. The photonic crystal heterostructure CDF consists of a horizontal waveguide and two ring resonators that have been installed, in symmetry to the horizontal axis, in two regions with different refractive indices. These ring resonators act as energy couplers and capture at their resonant frequencies the electromagnetic energy which is propagated in the bus waveguide. For the analysis of transmission characteristics and the band structure of the filter, two methods have been employed: the two-dimensional Finite–difference time domain method and the Plane Wave Expansion method. In the final structure, dropping efficiencies of 97 and 89 % can be achieved at ports D and B, respectively, and also an acceptable quality factor can be obtained in the communication window. The overall size of this device is 174.14  \(\upmu \hbox {m}^{2}\) . Due to its small size, this structure can be used in Wavelength Division Multiplexer applications in the Optical Integrated Circuits.     

Renewable sol-gel carbon ceramic electrodes modified with a Ru-complex for the amperometric detection of l-cysteine and glutathione

A renewable three-dimensional chemically modified carbon ceramic electrode containing Ru [(tpy)(bpy)Cl] PF₆ was constructed by sol-gel technique. It exhibits an excellent electro-catalytic activity for oxidation of l-cysteine and glutathione at pH range 2-8. Cyclic voltammetry was employed to characterize the electrochemical behavior of the chemically modified electrode. The electrocatalytic behavior is further exploited as a sensitive detection scheme for l-cysteine and glutathione by hydrodynamic amperometry. Optimum pH value for detection is 2 for both l-cysteine and glutathione. The catalytic rate constants for l-cysteine and glutathione were determined, which were about 2.1×10³ and 2.5×10³ M⁻¹ s⁻¹, respectively. Under the optimized condition the calibration curves are linear in the concentration range 5-685 and 5-700 μM for l-cysteine and glutathione determination, respectively. The detection limit (S/N=3) and sensitivity is 1 μM, 5 nA/μM for l-cysteine and 1 μM, 7.8 nA/μM for glutathione. The relative standard deviation (RSD) for the amperogram's currents with five injections of l-cysteine or glutathione at concentration range of linear calibration is <1.5%. The advantages of this amperometric detector are: high sensitivity, good catalytic effect, short response time (t<3 s), remarkable long-term stability, simplicity of preparation and reproducibility of surface fouling (RSD for six successive polishing is 3.31%). This sensor can be used as a chromatographic detector for analysis of l-cysteine and glutathione.     

Highly sensitive carbon paste electrode with silver-filled carbon nanotubes as a sensing element for determination of free cyanide ion in aqueous solutions

We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing element in ion-selective carbon paste electrodes for the determination of free cyanide in aqueous solution. The electrode was obtained by entrapping the silver-filled nanotubes into a carbon paste and displays a Nernstian response with a slope of 59.8?±?0.3?mV decade^?1, a very wide linear range (from 21.0?nM to 0.1?M of cyanide), a lower detection limit of 13.0?nM, and a response time of <2?min. The operational lifetime is up to 3?months without significant deviation in normal function.