Iranian Journal of Materials Science and Engineering

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Abstract
Gelatin (GEL) is most extensively used in various fields, particularly in therapeutics and pharmaceuticals. GEL was extracted from goat skin using hot temperature extraction process and compared with that of commercial GEL. The physico-chemical characterization and functional properties were investigated by using temperature denaturation (T_d), water-holding and fat-binding capacities (WHC and FBC), colour measurement and UV-light spectrum. In vitro biocompatibility was studied for the first time and was evaluated by blood coagulation index (BCI) and haemolytic tests for using as wounds dressing. The results revealed thermal stability of goat GEL at T_d 37°C. WHC and FBC capacities represented 2.5 and 1.2 g/ml, respectively. The hunter colour spaces a*, b* and L* showed a -0.27, -1.97 and 25.23 values, respectively. UV-Vis absorption spectrum of the goat GEL showed a maximum absorption peak at 280 nm. The in vitro anticoagulant activities of extracting GEL were higher than 70% after incubation for one hour. After being in contact with red blood cells for 1 h, the haemolysis ratio increased from to 0.46 to 1.4 when the concentration of goat GEL increased from 1 to 50 mg/ml suggesting the safety of the tested samples. These results suggest that thromboresistivity and hemocompatibility of this biopolymer retained the biological activity of our samples for biomaterial applications. According to this, goat GEL successfully competes with, and significantly could be useful for substitution of bovine in wound healing.

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The present study used a hydrothermal technique to synthesize undoped and Mn2+ doped CdS/Zn3(PO4)2 semiconducting nanocomposite materials. Powder X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectrometer, Fourier transform-Infrared Spectroscopy-FT-IR, and photoluminescence techniques were employed to study structural, optical, and luminescence properties of produced nanocomposites. The hexagonal structure of CdS and the monoclinic structure of Zn3(PO4)2 are both reflected in the powder X-ray diffraction spectra. When Mn2+ ions are present in the host lattice, a lattice distortion occurs, causing a phase change from the phase of γ-Zn3(PO4)2 to the β-phase of Zn3(PO4)2, without affecting the hexagonal phase of CdS. The average crystallite size of produced nanocomposites was 22-25 nm, and also calculated the lattice strain and dislocation density to better understand internal deformation of the samples. The FT-IR spectra were used to investigate the molecular vibrations and functional groups in the samples. The surface morphology of the nanocomposites is hexagonal spheres on rectangular shaped nano-flakes, and the interatomic distance between the hexagonal spheres is decreased as the doping concentration increases, forming a rod-like structure on the flakes. EDAX results confirm the presence of various relevant elements in the prepared samples. The quantum confinement of produced samples reduces as the Mn2+ doping concentration in the host lattice increases. The photoluminescence results demonstrate shallow trapped states due to the transition: d-d (4T1 → 6A1) of the tetrahedrally coordinated Mn2+ states and the impact of Mn2+ ions exhibiting several peaks in the UV-Visible region (365-634 nm) generating RGB (Red, Green, Blue) luminescence. Color coordinates and CCT values were calculated using the CIE diagram, and color correlated temperatures in the range of 2513–7307 K were discovered, which might be used in solid state lighting applications.

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This paper investigated the optimization, modelling and effect of welding parameters on the tensile shear load bearing capacity of double pulse resistance spot welded DP590 steel. Optimization of  welding parameters was performed using the Taguchi design of experiment method. A relationship between input welding paramaters i.e., second pulse welding current, second pulse welding current time and first pulse holding time and output response i.e, tensile shear peak load was established using regression and neural network. Results showed that maximum average tensile shear peak load of 26.47 was achieved at optimum welding parameters i.e., second pulse welding current of 7.5 kA, second pulse welding time of 560 ms and first pulse holding time of 400 ms. It was also found that the ANN model predicted the tensile shear load with higher accuracy than the regression model.

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In this research, after pressing in a cylindrical mold, the AA 7075 alloy swarf was melted and cast in a wet sand mold. After rolling and cutting, sheets with two different thicknesses of 6 and 20 mm were obtained. The sheets after homogenization were solutionized at 485°C for 30 and 90 minutes, respectively, due to differences in thickness and thermal gradients. The solutionized samples were quenched in 3 polymer solutions containing 10, 30, and 50% Poly Alekylene Glycol. The results showed that melting, casting, rolling, and heat treatment of AA7075 alloy swarf similar properties to this alloy is achievable. Microstructural studies by optical microscopes (OM), Field Emission Scanning Electron Microscopy (FESEM), and X-ray diffraction (XRD) showed that by increasing the quenching rate after the solutionizing process, precipitation increases during aging. The tensile test results indicated that as the quench rate and internal energy increase, the diffusion driving force would increase the precipitation of alloying elements. Hence, this leads to an increase in hardness and reduction of its strain after aging.

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Nowadays metal oxide nanoparticles and transition metal dichalcogenides play a vital role in various areas like optical sensors, solar cells, energy storage devices, gas sensors and biomedical applications. In the current research work, we synthesized ZrSe₂ nanoparticles by hydrothermal method. The ZrSe₂ nanoparticles were synthesis using precursors such as ZrOCl₂.8H₂O and Na₂SeO₃.5H₂O in the addition of surfactant cetyl trimethyl ammonia bromide CTAB and reductant hydrazine hydrate, respectively. By using synthesized ZrSe₂ nanopowder thick films were developed on a glass substrate
using the screen printing method. The structural properties of ZrSe₂ powder were studied by X-ray diffraction (XRD). The X-ray diffraction analysis revealed that the hexagonal crystal structure and crystalline size were found to be 55.75 nm. The thick films of ZrSe₂ were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The surface morphological analysis of ZrSe₂ nanostructured thick film shows hierarchical nanoparticles. The energy band gap of synthesized powder was calculated using a Tauc plot from UV-visible spectroscopy. The gas-sensing properties of ZrSe₂ thick films were studied. The developed ZrSe₂ thick films show maximum sensitivity and selectivity towards the ammonia NH₃ gas at an operating temperature of 120 °C and the gas concentration was 500 ppm. The developed thick films show fast response and recovery time.Nowadays metal oxide nanoparticles and transition metal dichalcogenides play a vital role in various areas like optical sensors, solar cells, energy storage devices, gas sensors and biomedical applications. In the current research work, we synthesized ZrSe₂ nanoparticles by hydrothermal method. The ZrSe₂ nanoparticles were synthesis using precursors such as ZrOCl₂.8H₂O and Na₂SeO₃.5H₂O in the addition of surfactant cetyl trimethyl ammonia bromide CTAB and reductant hydrazine hydrate, respectively. By using synthesized ZrSe₂ nanopowder thick films were developed on a glass substrate
using the screen printing method. The structural properties of ZrSe₂ powder were studied by X-ray diffraction (XRD). The X-ray diffraction analysis revealed that the hexagonal crystal structure and crystalline size were found to be 55.75 nm. The thick films of ZrSe₂ were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The surface morphological analysis of ZrSe₂ nanostructured thick film shows hierarchical nanoparticles. The energy band gap of synthesized powder was calculated using a Tauc plot from UV-visible spectroscopy. The gas-sensing properties of ZrSe₂ thick films were studied. The developed ZrSe₂ thick films show maximum sensitivity and selectivity towards the ammonia NH₃ gas at an operating temperature of 120 °C and the gas concentration was 500 ppm. The developed thick films show fast response and recovery time.

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This research explored the impact of the nickel-to-manganese ratio and the influence of the matrix phase on the properties of W-Ni-Mn tungsten heavy alloys (WHAs), aiming to determine the optimal composition for achieving desirable alloy properties.  For this purpose, tungsten, nickel, and manganese powders with specified weight percentages underwent two rounds of wet milling.  Powder mixtures were obtained with weight ratios of 90W-6Ni-4Mn, 90W-8Ni-2Mn, and 88W-10Ni-2Mn. These mixtures were then compressed through the cold pressing method at a pressure of 250 MPa. Subsequent reduction and sintering processes were carried out in a tube furnace at temperatures of 1150 and 1400 °C, respectively. Microstructural characterization was conducted using both optical and electron microscopy. The results showed that the change in chemical composition is not significantly effective on the sintering density of the samples and also the highest sintering density, reaching 90.11%, was achieved with the 88W-10Ni-2Mn sample. Furthermore, the results demonstrated that carburization of W-Ni-Mn WHAs during the sintering process led to an increase in the micro-hardness of the samples. The highest hardness, measuring 381 Hv, was observed in the 90W-6Ni-4Mn alloy, where carburization occurred. XRD results revealed that an increase in the nickel-to-manganese ratio led to a reduction in the peaks of manganese carbide and tungsten carbide. Consequently, this decrease in carbide peaks resulted in a reduction in hardness, reaching 352 Hv in the case of the 88W-10Ni-2Mn sample. Additionally, the alloys 90W-6Ni-4Mn and 88W-10Ni-2Mn both exhibited the lowest continuity, a value of 0.5. Fracture surface SEM images illustrated that the 90W-6Ni-4Mn alloy, characterized by the lowest nickel-to-manganese ratio (1.5), exhibited the highest trans-granular fracture mode involving cleavage and matrix tearing, which is considered desirable. Furthermore, an increase in the matrix phase content resulted in a shift of the preferred crack path, originating from the matrix phase.