GaN thin films were deposited by thermal evaporation onto
glass substrates at substrate temperature of 403 K and a thickness of
385 nm . GaN films have amorphous structure as shown in X-ray
diffraction pattern . From absorbance data within the range ( 200-
900 ) nm direct optical energy gap was calculated . Also the others
optical parameters like transmittance T, reflectance R , refractive
index n , extinction coefficient k , real dielectric constant 1 Î , and
imaginary dielectric constant 2 Î were determined . GaN films
have good absorbance and minimum transmittance in the region of
the visible light .
Ultrasonic pulse echo measurements on porous alumina as ceramic
material with porosities ranging from (20-40)% showed effect of volume
fraction of porosity on both thermal and elastic properties. A quadratic relationships, by using a least squares method, is deduced for the dependence of the shear velocity, longitudinal velocity, shear modulus, Young's modulus, bulk modulus, Poisson 's ratio, Debye temperature, specific heat, and thermal conductivity on the total porosity. By these relationships, the thermal and elastic properties results of pore-free alumina were calculated. The elastic properties results of
... Show MoreIn this research, the study effect of additive titanium dioxide powder (TiO2) as a lone composite ( Ep+TiO2) and a mixture of (TiO2) and silicon oxide (SiO2), ( Ep+ TiO2+SiO2)as a hybrid composite on the mechanical and physical properties for epoxy coating. Thescompsiteswere prepared by (Hand Lay- the molding) method. The samples were tested for compressive strength, surface hardness, modulus of elasticity, thermal conductivity and diffusion coefficient, from the results obtained showed improvement in mechanical properties after adding ceramic powders, as the alone composite (EP+ TiO2) had the highest compressive strength ( 53.738 ) ᴍPa, the hybrid composite ( EP+TiO2 +SiO2 ) had the
... Show MoreThe corona virus epidemic outbreak has urged an extreme worldwide effort for re‐purposing obtainable approved medications for its treatment. In this review, we're focusing on the chemicals properties andpharmacologicaleffectiveness of medicationsofsmallmolecule that are presently being evaluated in clinical trials for the management of corona virus (COVID‐19). The current review sheds light on a number of drugs that have been diagnosed to treat COVID‐19 and their biological effects.
In this investigation, metal matrix composites (MMCs) were manufactured by using powder technology. Aluminum 6061 is reinforced with two different ceramics particles (SiC and B4C) with different volume fractions as (3, 6, 9 and 12 wt. %). The most important applications of particulate reinforcement of aluminum matrix are: Pistons, Connecting rods etc. The specimens were prepared by using aluminum powder with 150 µm in particle size and SiC, B4C powder with 200 µm in particle size. The chosen powders were mixed by using planetary mixing setup at 250 rpm for 4hr.with zinc stearate as an activator material in steel ball milling. After mixing process the powders were compacted by hydraulic
... Show MoreThe mechanical properties of fiber-reinforced-polymer (FRP)
composites are dependent on the type amount, and orientation of fiber that is selected for a particular service. There are many commercially available reinforcement forms to meet the design requirements of the user. The ability of failure in the fiber architecture allows for optimized performance of a product that saves both weight and cost ( 12).
A modem technology is adopted to produce fibers (glass, kevelar,
and carbon) reinforced composite by using unsaturated polyester, where different volume fraction of these fibers are used (0, 0.2, 0.4, 0.6, 0.8, I)
reinfor
... Show MoreA numerical model for Polypropylene 575 polymer melts flow along the solid conveying screw of a single screw extruder under constant heat flux using ANSYS-FLUENT 17.2 software has been conducted. The model uses the thermophysical properties such as Viscosity, thermal conductivity, Specific heat and density of polypropylene 575 that measured as a function of temperature, and residence time data for process simulation. The numerical simulation using CFD models for single screw extruder and the polymer extrusion was analysed for parameters such as (thermal conductivity, specific heat, density and viscosity) reveals a high degree of similarity to experimental data measured. The most important outcome of this study is that geometrical, parame
... Show MoreNuclear structure of 29-34Mg isotopes toward neutron dripline have been investigated using shell model with Skyrme-Hartree–Fock calculations. In particular nuclear densities for proton, neutron, mass and charge densities with their corresponding rms radii, neutron skin thicknesses and inelastic electron scattering form factors are calculated for positive low-lying states. The deduced results are discussed for the transverse form factor and compared with the available experimental data. It has been confirmed that the combining shell model with Hartree-Fock mean field method with Skyrme interaction can accommodate very well the nuclear excitation properties and can reach a highly descriptive and predictive power when investiga
... Show MoretA novel synthesis procedure is presented for preparing triethanolamine-treated graphene nanoplatelets(TEA-GNPs) with different specific areas (SSAs). Using ultrasonication, the covalently functionalizedTEA-GNPs with different weight concentrations and SSAs were dispersed in distilled water to prepareTEA-GNPs nanofluids. A simple direct coupling of GNPs with TEA molecules is implemented to synthesizestable water-based nanofluids. The effectiveness of the functionalization procedure was validated by thecharacterization and morphology tests, i.e., FTIR, Raman spectroscopy, EDS, and TEM. Thermal conduc-tivity, dispersion stability, and rheological properties were investigated. Using UV–vis spectrometer, ahighest dispersion stability of 0.876
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