Observation of Enhanced Magnetic Pinning in Sm3+ Substituted Nanocrystalline MnZn Ferrites Prepared by Propellant Chemistry Route

We report the effect of Sm3+ substitution on the structural and magnetic properties of nanocrystalline Mn0.5Zn0.5SmyFe2-yO4 (y = 0.00, 0.01, 0.03 and 0.05) samples prepared by propellant chemistry route using a mixture of fuels. Rietveld refinement of XRD patterns confirmed the formation of cubic spinel phase with space group View the MathML source. The lattice parameter values decreased with Sm3+ substitution up to y = 0.03, but with a noticeable increase for the sample with y = 0.05. In all the samples, entire amount of Zn2+ and Sm3+ were found to be present at the A and B sites, respectively. A distribution of Mn2+ ions at the tetrahedral (A) and the octahedral (B) sites of the spinel Mn0.5Zn0.5Fe2O4 was observed. The microstructures of the samples were observed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). For all the samples, the average crystallite size decreased with increase in Sm3+ concentration, as determined using Williamson-Hall method. The FTIR spectra showed prominent absorption bands at ∼540 and ∼390 cm−1 corresponding to the stretching vibrations of the metal ion complexes at the tetrahedral (A) and the octahedral (B) sites, respectively. Magnetic properties such as saturation magnetization (Ms), remanence (Mr) and magneton number (ηB) were found to decrease, while the coercivity (Hc) and reduced remanence (Mr/Ms) of the samples were found to increase with increasing Sm3+ content. The increase in Hc with increase in Sm3+ concentration is interpreted as the enhanced pinning of the magnetic moments at the magnetic defects created by Sm3+ ions, which is further confirmed by Mössbauer spectroscopy through a nearly constant magnetic hyperfine field. This results in an increase in the magnetic particle size in spite of decreasing average crystallite size. Our work suggests that, Sm3+ substitution can be used to alter the magnetic hardness of Mnsingle bondZn ferrites and to enable them to be used as potential materials for various technological applications

Synthesis and study of Structural, Microstructural and Dielectric Properties of Ce3+ doped Co-Ni Ferrites for automotive applications

Nano crystalline spinel ferrites of Co0.5Ni0.5CexFe2−xO4 (x=0.01, 0.015, 0.02, 0.025 and 0.03) was prepared by modified solution combustion method using a mixture of fuels for the first time. The influence of rare earth Ce3+ substitution at the Fe3+ site on the structural, microstructural and dielectric properties of Co0.5Ni0.5CexFe2-xO4 was investigated. The X-ray diffraction (XRD) studies confirmed the formation of monophasic nano crystalline samples without any secondary phases. The crystallite size decreases and density increases with the increases of Ce3+ contents. Surface morphology was studied through Scanning Electron Microscopy (SEM). Dielectric properties of these ferrites have been studied at room temperature using impedance analyzer in the frequency range up to 20 MHz. The effect of frequency and composition on dielectric constant (ε’), dielectric loss (tanδ) and ac conductivity (σac) have been discussed in terms of hopping of charge carriers (Fe2+↔Fe3+). The decrease in dielectric loss with frequency follows Debye's relaxation phenomena. Both the variation in tan loss and dielectric loss with frequency shows a similar. AC conductivity increases with the increases of frequency which directly proportional to concentration of Ce3+ ions follows Jonscher law. These Cerium doped Cobalt-nickel ferrites are very helpful for automotive applications

Evolution of microstructure and crystallographic texture during dissimilar friction stir welding of duplex stainless steel to low carbon-manganese structural steel

Electron backscattered diffraction (EBSD) was used to analyze the evolution of microstructure and crystallographic texture during friction stir welding of dissimilar type 2205 duplex stainless steel (DSS) to type S275 low carbon-manganese structural steel. The results of microstructural analyses show that the temperature in the center of stirred zone reached temperatures between Ac 1 and Ac 3 during welding, resulting in a minor ferrite-to-austenite phase transformation in the S275 steel, and no changes in the fractions of ferrite and austenite in the DSS. Temperatures in the thermomechanically affected and shoulder-affected zones of both materials, in particular toward the root of the weld, did not exceed the Ac 1 of S275 steel. The shear generated by the friction between the material and the rotating probe occurred in austenitic/ferritic phase field of the S275 and DSS. In the former, the transformed austenite regions of the microstructure were transformed to acicular ferrite, on cooling, while the dual-phase austenitic/ferritic structure of the latter was retained. Studying the development of crystallographic textures with regard to shear flow lines generated by the probe tool showed the dominance of simple shear components across the whole weld in both materials. The ferrite texture in S275 steel was dominated by D 1, D 2, E, E¯ , and F, where the fraction of acicular ferrite formed on cooling showed a negligible deviation from the texture for the ideal shear texture components of bcc metals. The ferrite texture in DSS was dominated by D 1, D 2, I, I¯ , and F, and that of austenite was dominated by the A, A¯ , B, and B¯ of the ideal shear texture components for bcc and fcc metals, respectively. While D 1, D 2, and F components of the ideal shear texture are common between the ferrite in S275 steel and that of dual-phase DSS, the preferential partitioning of strain into the ferrite phase of DSS led to the development of I and I¯ components in DSS, as opposed to E and E¯ in the S275 steel. The formations of fine and ultrafine equiaxed grains were observed in different regions of both materials that are believed to be due to strain-induced continuous dynamic recrystallization (CDRX) in ferrite of both DSS and S275 steel, and discontinuous dynamic recrystallization (DDRX) in austenite phase of DSS

Sequence Analysis and Phylogenetic Studies of Hypoxia-Inducible Factor-1α

Hypoxia-inducible factors (HIF) belong to the basic helix loop helix–PER ARNT SIM (bHLH-PAS) family of transcription factors that induce metabolic reprogramming under hypoxic condition. The phylogenetic studies of hypoxia-inducible factor-1α (HIF-1α) sequences across different organisms/species may leave a clue on the evolutionary relationships and its probable correlation to tumorigenesis and adaptation to low oxygen environments. In this study, we have aimed at the evolutionary investigation of the protein HIF-1α across different species to decipher their sequence variations/mutations and look into the probable causes and abnormal behaviour of this molecule under exotic conditions. In total, 16 homologous sequences for HIF-1α were retrieved from the National Center for Biotechnology Information. Sequence identity was performed using the Needle program. Multiple aligned sequences were used to construct the phylogeny using the neighbour-joining method. Most of the changes were observed in oxygen-dependent degradation domain and inhibitory domain. Sixteen sequences were clustered into 5 groups. The phylogenetic analysis clearly highlighted the variations that were observed at the sequence level. Comparisons of the HIF-1α sequence among cancer-prone and cancer-resistant animals enable us to find out the probable clues towards potential risk factors in the development of cancer

Sensorless Field Oriented Control in Six phase Permanent Magnet Synchronous Machine

An ever increasing emphasis on climate change and limiting carbon emission into the atmosphere, has led to lot research and innovation towards the greener mode of transport in the areas such as More Electric Aircraft (MEA), electric ship propulsion, electric and hybrid vehicles. Electric machines are largely used as the mean of a propulsion system for all the transportation related application, except for the aircraft where it is used controlling subsystems. For improving the efficiency, reliability, and maintainability in an aircraft, the technological advances in the aerospace industry is moving towards the electrification of onboard services by reducing or removing the presence of the hydraulic, mechanical and air/pneumatic systems. The modular design multiphase machine offers a number of advantages compared to the traditional three-phase machine, in terms of the fault tolerance and reliability in aerospace applications. Modular systems refer to the system which can be decomposed into a number of independent modules or components. This system can have their faulted modules bypassed and continue operation after fault, increasing system availability. Modular design permanent magnet drives are widely selected for aerospace application in the high-performance drive systems, due to their fault tolerant capability, power density, reliability and high efficiency associated with the control possibilities. At first, the modular design of the Permanent Magnet Synchornous Machin and power converter under consideration is explained using literature. Further, application of the modularity to the whole electrical drive system including the control circuit is presented. Subsequently, sensorless field oriented control (FOC) was implemented in the three phases of the machine using the inbuilt InstaSPIN FOC algorithm in microcontroller device. The control technique is later extended from three phase to six phase machine.Electrical Engineering, Mathematics and Computer ScienceElectrical Sustainable Energ

Sequence Analysis and Phylogenetic Studies of Hypoxia-Inducible Factor-1α

Hypoxia-inducible factors (HIF) belong to the basic helix loop helix–PER ARNT SIM (bHLH-PAS) family of transcription factors that induce metabolic reprogramming under hypoxic condition. The phylogenetic studies of hypoxia-inducible factor-1α (HIF-1α) sequences across different organisms/species may leave a clue on the evolutionary relationships and its probable correlation to tumorigenesis and adaptation to low oxygen environments. In this study, we have aimed at the evolutionary investigation of the protein HIF-1α across different species to decipher their sequence variations/mutations and look into the probable causes and abnormal behaviour of this molecule under exotic conditions. In total, 16 homologous sequences for HIF-1α were retrieved from the National Center for Biotechnology Information. Sequence identity was performed using the Needle program. Multiple aligned sequences were used to construct the phylogeny using the neighbour-joining method. Most of the changes were observed in oxygen-dependent degradation domain and inhibitory domain. Sixteen sequences were clustered into 5 groups. The phylogenetic analysis clearly highlighted the variations that were observed at the sequence level. Comparisons of the HIF-1α sequence among cancer-prone and cancer-resistant animals enable us to find out the probable clues towards potential risk factors in the development of cancer