Sharif Digital Repository

We report the results of the electronic structure calculation of a newly discovered member of the YBCO high-T c family, i.e., Y 3Ba 5Cu 8O 18 (Y358) with T c>100, based on the full-potential linearized augmented plane waves method (FP-LAPW) of density functional theory in the generalized gradient approximation (GGA). The evolution of the number of hole carriers in different sites of the CuO 2 planes and CuO chains has been investigated in comparison with the other YBCO family members, i.e., Y123, Pr123, Y124, and Y247. The results suggest that pumping hole carriers out of the chains toward the planes enhances the transition temperature. The band structure calculations have been performed for... 

An easy method for preparing CuO nanoparticles incorporated in a mesoporous structure was presented based on the thermal decomposition of a copper complex. The novel copper coordination compound of [Cu(anic)2]·0.75H2O (anic= 2-aminonicotinate) with the microflake morphology was synthesized through the reaction of 2-aminonicotinic acid (Hanic) and copper(II) nitrate. Using elemental analysis and Fourier transform infrared (FTIR) spectroscopy, the chemical composition of CuC12H11.5N4O4.75 was proposed. Calcination process at 550 °C for 4 h transformed the microflakes into CuO nanoparticles incorporated in a mesoporous structure. The FTIR peaks assigned to 2-aminonicotinate were completely... 

Numerical investigation on the application of nanofluids in Micro-Pin-Fin Heat Sinks (MPFHSs) has been presented in this paper. To investigate flow and heat transfer behavior in MPFHS the three-dimensional steady Navier-Stokes and energy equations were discretized using a finite volume approach and have been solved iteratively, using the SIMPLE algorithm. DI-water is used as a base coolant fluid while the nanoparticles used in the present study are CuO nanoparticles with mean diameters of 28.6 and 29 nm and Al 2O 3 nanoparticles with mean diameters of 38.4 and 47 nm. The results show that (i) a significant enhancement of heat transfer in the MPFHS due to suspension of CuO orAl 2O 3... 

The present study deals with the investigation of Cu2+, Ni2+ and Pd2+ chelating potential of the Schiff base, (E)-N-(2-((2-hydroxybenzylidene)amino)benzyl)-4-methylbenzenesulfonamide (H2SB). Crystal structures of Ni(HSB)2, Pd(HSB)2 and Cu(HSB)2 have been elucidated from single crystal X-ray diffraction data. NMR spectroscopy showed the presence of two conformers of Pd(HSB)2 in solution, both with an E configuration of the ligand. The determination of binding constants by fluorescence quenching showed that affinity of H2SB to Cu2+ in solution is higher than for Ni2+ and Pd2+. Since there is a high demand for selective, sensitive, rapid and simple methods to detect copper in aqueous samples... 

Recyclable CuO nanoparticles provide an efficient, economic, and novel method for the synthesis of quinoxaline, benzoxazine, and benzothiazine. This method provides a wide range of substrate applicability, avoids the use of organic solvents, and gives benzoheterocycles in satisfactory yields  

Copper oxide-titania catalysts with nanocrystalline mesoporous structure were prepared by sol-gel technique using tetra isopropyl ortho titanate (TiPT) as the inorganic precursor and amino-2 ethanol as the swelling agent. Characterization was performed using X-ray diffraction (XRD), fourier transformed infrared spectra (FTIR), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy (DRS), and N2 adsorption-desorption measurements. It was found that CuO (0.025-0.1 mol ratio) has some effect on the particle size, surface area, pore-volume, pore-diameter, crystallinity of the particles, and crystalline phase of TiO2 nanocrystalline. The results indicated that 0.1 CuO-TiO2... 

Copper oxide-titania catalysts with nanocrystalline mesoporous structure were prepared by sol-gel technique using tetra isopropyl ortho titanate (TiPT) as the inorganic precursor and amino-2 ethanol as the swelling agent. Characterization was performed using X-ray diffraction (XRD), fourier transformed infrared spectra (FTIR), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy (DRS), and N2 adsorption-desorption measurements. It was found that CuO (0.025-0.1 mol ratio) has some effect on the particle size, surface area, pore-volume, pore-diameter, crystallinity of the particles, and crystalline phase of TiO2 nanocrystalline. The results indicated that 0.1 CuO-TiO2... 

Purpose: This paper aims to to simulate the flow and heat transfer during free convection in a square cavity using double-multi-relaxation time (MRT) lattice Boltzmann method. Design/methodology/approach: The double-MRT lattice Boltzmann method is used, and the natural convection fluid flow and heat transfer under influence of different parameters are analyzed. The D2Q5 model and D2Q9 model are used for simulation of temperature field and flow field, respectively. The cavity is filled with CuO-water nanofluid; in addition, the thermo-physical properties of nanofluid and the effect of nanoparticles’ shapes are considered using Koo–Kleinstreuer–Li (KKL) model. On the other hand, the cavity is... 

Hydrothermal synthesis of CuO nanoparticles under near-critical and supercritical conditions was investigated from two different standpoints in the current study. The first standpoint was optimization of "yield", "purity", and "size of the nanoparticles" that were optimized at T = 500 °C, time = 2 h, [Cu(NO3)2] = 0.1 mol dm-3, and pH 3. This was achieved by undertaking an orthogonal experiment design methodology and performing different instrumental analyses, such as X-ray diffractometry, inductively coupled plasma spectrometry, and transmission electron microscopy, along with treatment of the data by analysis of variance (ANOVA). The second goal of the study was elucidation of the... 

In this paper, ultra-small CuO nanoparticles (NPs) were synthesized through a mechanochemical method using two different Cu-containing precursors (i.e. CuSO4·5H2O and CuCl2·2H2O), and their structure and antibacterial activity were studied. From the microstructural studies, it was observed that CuO NPs have a spherical morphology and a narrow size distribution with 7 and 14 nm median particle sizes for CuCl2·2H2O and CuSO4.5H2O precursors, respectively. The CuCl2·2H2O derived nanoparticles showed more antibacterial activity than CuSO4.5H2O derived nanoparticles. The minimum inhibitory concentration (MIC) of the synthesized nanoparticles (derived from both precursors) against E. coli and... 

In this study, we present fabrication and characterization of a gas ionization sensor based on high aspect ratio one-dimensional CuO nanowires as the field enhancing medium. Self-organized arrays of CuO nanowires have been synthesized based on a low-cost thermal oxidation method and integrated into a gas ionization sensor (GIS). The self-organized arrays of CuO nanowires have been employed to detect the identity of several gas species such as He, Ar and CO at ambient temperature and pressure. The sharp nanoscale size of CuO tips provide very high electric fields at moderate voltages (less than 100 V) and provoke the breakdown of different gases. The reduced breakdown current of the metal... 

Enhancing stability against photocorrosion and improving photocurrent response are the main challenges toward the development of cupric oxide (CuO) based photocathodes for solar-driven hydrogen production. In this paper, stable and efficient CuO-photocathodes have been developed using in situ materials engineering and through gold-palladium (Au-Pd) nanoparticles deposition on the CuO surface. The CuO photocathode exhibits a photocurrent generation of ∼3 mA/cm2 at 0 V v/s RHE. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis and X-ray spectroscopy (XPS) confirm the formation of oxygen-rich (O-rich) CuO film which demonstrates a highly stable photocathode with retained... 

This research focused on making novel low-voltage SnO2 varistors by CuO addition on conventional high-voltage SnO2 varistors. Moreover, the withstand surge capability of samples was studied. The results showed that CuO addition enhances grain growth of SnO2 and coarse-grained SnO2 varistors with simple microstructures were acquired in 1 mol% CuO-doped sample. This coarse-grained SnO2 varistor presented a high nonlinear coefficient (23) and low leakage current density (23 µA/cm2) with low breakdown field value of 0.6 kV/cm. Despite the large grain size, the low residual voltage ratio (2.3) was obtained for this sample compared to the CuO-free sample. The decrease in grain electric resistivity... 

Up to now, attempts for developing coarse-grained SnO2-based varistors which exhibit high nonlinearity property at lower voltage have become a challenge without any prominent result because of its unknown grain growth mechanism. In this study, the effect of CuO addition to SnO2-based varistors as a grain growth enhancer additive on microstructural development, grain growth kinetics, and electrical properties was investigated. The characterization of grain growth kinetics showed that CuO addition encouraged grain growth and enhanced the grains size as it could be seen in the activation energy which decreased from 594 kJ/mol to 364 kJ/mol. In the samples with a low amount of CuO, the solute... 

In this study, the effect of adding 5–12.5 wt% CuO to TiO2 on photocatalytic properties of the nano-composite TiO2/CuO was investigated. The products were characterized by X-ray diffractometer, SEM, Brunauer–Emmett–Teller (BET), and DRS. BET-specific surface area of the TiO2/CuO composites was lower than that of the pure TiO2. Incorporation of CuO into TiO2 shifted absorption spectra to the visible region. As the CuO content increased from 0 to 12.5%, a clear decrease in optical band gap from 2.95 to 2.30 eV was observed. The photocatalytic performance was determined by methyl orange degradation and cyanide photo-oxidation under ultraviolet irradiation. However, the excessive incorporation... 

The bidentate carboxamide ligand N-(thiazole-2-yl) picolinamide (LH) was synthesized in the environmentally friendly ionic liquid TBAB, and the five-coordinated CuII-complex, [Cu(L)2(H2O)].CHCl3 (1) was synthesized from LH and copper(II)acetate. Cupric oxide [CuO] nanoparticles (2) have been prepared by the thermal decomposition of (1) as a new precursor at 600 °C for 3 h under air atmosphere. (1) was characterised using FT-IR spectroscopy, elemental analyses and its solid state structure was confirmed by single crystal X-ray diffraction. (2) were identified by FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray analysis and thermo-gravimetric... 

Purpose: The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach: For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings: The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization,... 

In the current study, CuO nanoparticles were dispersed in a mixture of Ethylene Glycol-Water (60/40 wt. %) to prepare stable nanofluid in different concentrations (0.05 − 0.8 vol. %). The samples were used as the coolant fluid in a specific car radiator to evaluate the thermal performance of nanofluid and base fluid in the system. Five different and novel Machine-learning methods were applied over experimental data to predict the Nusselt number and output temperature of the coolant in the system. These methods are M5 tree regression, Linear and Cubic Multi-Variate Adaptive Regression Splines (MARS), Radial Basis Function (RBF), and Artificial Neural Network-Levenberg Marquardt Algorithm... 

Ultra fine CuO nanoparticles In the range of 2 ± 0.2 nm were synthesized by the supercritical hiydrotliermal method in a batch reactor. Itwas demonstrated that elevating the pH of the Cu2+ precursor solution to around 6 (neutral condition) not only does not lead to excessive agglomeration of the particles, but also reduces particle size and in general promotes their nanoscale characteristics. Prepared nanoparticles were immobilized in the biopolymcric matrix of barium alginate and calcined at different temperatures resulting in micro spherical granules of high porosity and elevated mechanical strength. The fabricated samples were characterized using x-ray diffractometry (XRD), transmission...