Search

The present work investigates the effects of antimony and hot rolling on the microstructure, texture, and magnetic properties of a 1.2 wt%Si electrical steel. For this purpose, three samples with 0.002, 0.012, and 0.026 wt% antimony were produced by melting in an induction furnace and casting into ingots, followed by hot rolling with a 75 % reduction. The aim was to better understand the interaction effects of adding antimony and hot rolling on the microstructure, texture, and magnetic properties. Microstructural studies were performed using optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The macrotexture measurement was performed via X-ray diffraction (XRD), while magnetic properties were measured by a vibrating sample magnetometer (VSM). The results showed that increasing the antimony content gradually reduces the grain size, which is due to the effect of antimony on the migration rate of grain boundaries. This behavior was observed in both as-cast and hot-rolled samples. The texture in as-cast samples is random, and θ-fiber is observed after hot rolling. The examination of the texture parameter (TP) showed that the sample with 0.002 wt%Sb has a higher TP compared to other samples. Moreover, the lowest levels of coercivity and remanence are observed in this sample, which is due to the inverse relationship between the grain size and coercivity. The addition of antimony reduces the grain size, thus destroying the magnetic properties under these conditions.

‎In this paper‎, ‎we investigate an improved method for stabilizing a class of uncertain chaotic nonlinear dynamical system‎. ‎Our approach follows techniques of optimal principle for time-delayed feedback control and adaptive tracking control theory for stabilizing unstable periodic orbits in a chaotic bounded attractor‎. ‎The uncertain parameters expressed in the system can be separated‎. ‎Analysis and proof are presented using the Lyapunov stability theorem‎. ‎In particular‎, ‎we use the adaptive control theory to design an adaptive law for the estimation of uncertain time-delayed controlled chaotic nonlinear dynamical systems‎. ‎The predictions are presented by numerical simulation through the Rossler system to demonstrate theoretical results‎.

The aims of this research were to evaluate the effects of different thermomechanical treatments on the microstructure and investigate some of the mechanical properties of a TWIP steel rich in Mn & Al. So, a block of a TWIP steel with nominal composition Fe-17.5Mn-1.36Al-0.8C was cast and then subjected to hot rolling followed by cold rolling and heat treatment. Cold rolling was performed before heat treatment in order to reduce the grain size and improve the tensile and fatigue properties. X-ray diffraction technique was used before and after the heat treatment to evaluate the possibility of any phase formation. No sign of martensitic transformation after cold deformation was observed. However, by increasing the amount of cold deformation, the number of mechanical twins and slip band increased resulted to an increase in hardness and strength. The best tensile and fatigue result were obtained after 47% thickness reduction and annealing at 715˚C for 10 min. Under these conditions, the mean grain size reduced from 138 to 9 μm resulted to an increase in yield strength from 395 to 510 MPa, and the fatigue life improvement from the mean life of 10200 for the cast sample to 21500 cycles for the treated sample, when these samples underwent fatigue tests at a stress range of 650 MPa and R=0. In addition, the diameter and depth of dimples in fracture surfaces decreased by reducing the grain size but the fracture mode was remained ductile and adequate plastic deformation occurred before failure.

The aim of this study was to investigate the effect of under electro slag re-melting (ESR) process on the fatigue behavior of GTD-450 steel used for manufacturing gas turbin blades. These parts are always at risk of failure due to fatigue. Refining of steel by ESR process is one of the most important modern methods of steelmaking in order to achieve a homogeneous structure, minimal elemental and structural segeregation, as well as reducing non-metallic impurities in terms of their number and size and most importantly their uniform distribution in the steel structure. Due to dependency of fatigue properties of steels on structural factors of steel, the role of ESR process using different slag compositions on this important property of GTD-450 steel was investigated. Microstructural studies by optical and electron microscopes showed that grain size of ESR samples were averagely 10% finer than non-ESR ones. As well as performing various mechanical tests including tensile and fatigue on samples prepared in different conditions, showed that although ESR had a minor effect on tensile properties of steel but impact energy of steel in ESR condition were averagely 16% more than non-ESR condition. Finally, the core finding of this paper is that, fatigue life of GTD-steel turbine blade produced via ESR method can be improved by 30%.

This study investigates the synthesis of Al/MoS2 nanocomposite coating by the electro spark deposition (ESD) method for its lubricating properties. ESD method was selected because it is a very easy, rapid, and cost-saving method and the resulting coating has a strong bonding with the substrate. As a substrate, a Ti-6Al-4V alloy sheet containing 6.12 % Al, 4.06 % V, 0.19% Fe, and 0.05 % Ni was used. For coating, an aluminum-molybdenum disulfide composite electrode in the form of a cylindrical rod was employed. Three frequencies of 5, 8, and 11 kHz, three current limits of 15, 25, and 35 amps, and three duty cycles of 50, 60, and 70% were used in the coating operation. AFM analysis was used to study the topography, morphology, and calculate roughness. The samples were then subjected to hardness tests. To determine the wear resistance of the samples, pin on disk tests were performed. XRD analysis was performed to identify the phases on the surface of the coated samples. SEM was used to examine the microstructure of the coating before and after wear testing, in order to determine the wear mechanism. The results indicated that the Al/MoS2 nanocomposite coating was synthesized on the substrate surface. The hardness of the reference sample is 353 Vickers, and that of the coated samples is about 200 Vickers. For the reference sample, the roughness was measured at 15.7 nm, and for the coated sample at 268.1 nm. As spark energy increased, the coefficient of friction increased by approximately 0.09. As spark energy increased, the wear rate increased by 27%. A significant increase in the Lancaster coefficient occurred around 5 joules of energy. According to the wear rate results, the sample with the lowest thickness wears 4% less than the sample with the highest thickness. The wear rate of sample 351170 is 78% lower than that of sample 150550.

Abstract Hepatocellular carcinoma is one of the leading causes of cancer-associated death across the globe. Malignant ascites are the major clinical attributes in cancer patients. Despite the advancements in HCC treatments such as chemotherapy, radiotherapy, surgery, and hormonal therapy, researchers are pursuing novel natural edible compounds for the treatment of cancer to eliminate dreadful side effects. Pleurotus ostreatus is one of the most edible cuisines in Asia as well as all over the world. It has been a source of nutritious diet since it was classified as an edible mushroom with no or negligible side effects. The present study focused on the natural anti-cancerous and anti-ascites capabilities of polysaccharides extracted from Pleurotus ostreatus in-vivo as well as in-vitro. Administration of polysaccharide Pleurotus ostreatus showed a significant decrease in tumor cell metastasis while the increase in the survival period among mice models of H22 malignant ascites. Downregulation of regenerative genes Foxp3 and Stat3 and secretion of immunological factors such as IL-2, TNF α, and INF γ were observed after treating with the partially pure extracted polysaccharide. Twining with the hypothesis of tumor suppression in-vivo model polysaccharide showed a decrease in invasion and migration abilities and henceforth responsible for the gene regulation such Cytochrome C which supposedly induced the chain of gene regulation process resulting in apoptosis in HCC cell lines observed in-vitro experiments. Collective research findings manifested that polysaccharide extracted from Pleurotus ostreatus bears anti-proliferative activity and thus influence tumor suppression in-vivo and in-vitro against hepatocellular carcinoma and can be used for therapeutic purposes as a potential anti-cancerous source in the future.

This study examined the heat characteristics of a vertical shell-tube thermal storage system with phase change materials. A three-dimensional finite volume method involving an interface mesh was employed to reduce the computational time. The regime of the heat transfer flow was laminar based on the heat transfer fluid flow regime. The numerical method was first validated against data obtained from the literature, and a Mushy coefficient of 105 was found to yield accurate results. Furthermore, the effects of a continuous porous medium with varying porosity and locally porous media in three different zones of the phase change system on related parameters of the phase changing process were investigated. These parameters include temperature changes, the solid-liquid interface, the distribution of the liquid fraction, and the total melting time of the phase change materials. It was found that as the porosity decreased, it was possible to reduce the melting time by up to 82%. Furthermore, using the middle part of the phase change material as a porous zone led to an increase in temperature gradient and a reduction in the resistance of the PCM to melting, which eventually increased the rate of phase change.