Papers by Keyword: Susceptibility

Abstract: High-Temperature Superconductor Cuprates (HTSC) are materials that exhibit superconductivity at higher temperatures compared to conventional superconductors. The effect of impurities in HTSC in the overdoped region is very important to study because there are interesting phenomena such as the spin-glass state. In this study, we have synthesized Eu₂₋_(x+y)Ceₓ_-yCu₁₋_yFe_yO₄₊_α₋δ (ECCFO) materials with x = 0.18; 0.19; 0.20; 0.21 and 𝑦 = 0; 0.03 using the solid-state reaction method to study the effect of Fe impurities on the crystal structure and magnetic properties in the overdoped region. The crystal structure was characterized using XRD measurements, and the magnetic properties were characterized using SQUID measurements at temperatures of 2 K to 30 K with a magnetic field of H = 5 Oe. The XRD measurement results show that all samples have a tetragonal T' structure, which corresponds to the ECCO crystal structure. The values of the lattice parameter c, unit cell volume, and CuO bond length increase with increasing y. From the SQUID measurements, for y = 0 with x = 0.19; 0.20, shows superconducting properties with T_c onset around 11 K. For variation y = 0.03 with x = 0.18; 0.20; 0.21, antiferromagnetic-like properties were observed, while the samples with x = 0.19 shows paramagnetic properties. These results indicate that Fe as a magnetic impurity affects spin arrangement in the conduction layers, as evidenced by an increase in the Curie constant and the effective magnetic moment.

Abstract: Bi_1.6Pb_0.4Sr₂Ca_2-xEu_xCu₃O_δ cuprates superconductor doped with Eu nanoparticles (x = 0.0000, 0.0025, 0.0200 and 0.0500) were synthesized through conventional solid state reaction method. Crystalline sucrose was added during pelletization and burn at 400°C for two hours to create low density sample. The effect of doping Eu₂O₃ nanoparticles on the structural and superconducting properties by means of critical temperature (T_c), critical current density (J_c), X-ray diffraction (XRD) together with Field Emission Scanning Electron Microscopy (FESEM) and Alternating Current Susceptibility (ACS) were studied. Based on XRD analyses, the crystallographic structure has shown slightly changed from tetragonal to orthorhombic. The amount of 2223 phase gradually decreased with the increment of Eu concentration which indicates that Eu nanoparticles substitution favours the growth of 2212 phases. The resistivity measurements show that the highest T_c value for doped samples found at 90 K for x = 0.0025. The FESEM images showed that the plate-like grains become smaller and distributed randomly without specific alignment due to the increment of Eu concentration.

Abstract: Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu_1.88Ce_0.12Cu_1-yZn_yO_4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, T_c and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu_1.88Ce_0.12Cu_1-yZn_yO_4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.

Abstract: A modelling system was utilised to simulate the movement and behaviour of oil slicks for two types of hydrocarbons, a diesel and another residual, considering hydrodynamic variations. Susceptible areas to oil touching were found in adjacent regions of two vessel manoeuvring zones, in two types of zones, one in a marine coastal and another in an estuarine environment. The evaporation rates were calculated for an estimate of the mass losses. For the maritime zone, the oil particles reached the vicinity of the beaches in approximately 4 to 8 hours after the beginning of the spill simulations, while for the estuary in approximately 1 hour. For the scenarios with diesel oil, mass losses oscillated between 13 to 16% in the estuarine region, and between 23 and 29% in the marine coastal zones. The evaporation rates for scenarios with residual oil, between 2 and 5%, were considerably lower than for diesel (15 and 22%), especially for spills simulated in the estuarine region, where the oil particles reached the lagoon banks after 1 hour. Mass losses by evaporation were more intense in marine coastal areas than for oil spills simulated in estuarine regions, possibly due to the more intense hydrodynamic conditions and the longer time that the oil needs to reach the coast. The fluctuations of observed environmental conditions justify the need for a robust number of simulations for reducing the uncertainties related to the oceanographic and meteorological variability that affect oil spill movement.

Abstract: Numerical models have been widely used to simulate and predict the behavior and transport of oil spills in marine environments. Their behavior is governed by physical, chemical and biological processes which are related to the hydrocarbon properties, hydrodynamic and weather conditions, and other environmental variables. The transport and interactions of oil particles were evaluated in simulations reproducing two oil spills recorded in the northern part of the Southern Brazilian Shelf (SBS). The numerical simulations were performed using the ECOS (Easy Coupling Oil System) model coupled to the three-dimensional hydrodynamic module TELEMAC3D. The hydrodynamic model provides the variables needed by oil spill model to calculate and infer the properties and behavior of the oil slick. The results indicate that the local wind forcing is the most important factor in determining the oil fate, followed by the intensities and directions of coastal currents. Regarding the events, in 2012 the oil reached the coast after 10 hours of the leak while in 2014 it was transported towards the ocean. The simulation strategy used in this article did not prove to be appropriate for estimates of the oil risk in the region, due to the distinct susceptibility responses between the events simulated.

Abstract: In this work we report the study of magnetic relaxation process presented in the bimetallic Co/Au nanoparticles prepared utilizing the reverse micelle method. Structural analysis of the system using synchrotron X-ray diffraction and transmission electron microscopy documented individual nanocrystalline particles of average size about 7 nm. Magnetic properties of the particles were examined by ac magnetic susceptibility measurements at temperature range 2 – 300 K at different frequencies of magnetic field. The relaxation process was revealed at temperature about 6 K. Application of several theoretical models on experimental data of magnetic susceptibility confirmed strong inter-particle interactions and novel superspin glass state in the nanoparticle system at low temperatures.

Abstract: The Henkel plot and the Δm plot of a longitudinal barium ferrite hard disk and γ-Fe2O3 flexible disk were simulated by the improved Preisach-DOK model.The study results show that the barium ferrite exhibit large positive interactions, as shown by large positive in the Δm plot, and tend to resist demagnetization, leading the oriented barium ferrite possess the unusual remanence characteristic.

Abstract: Polymorphisms in the regulatory regions of cytokine genes can affect the level of cytokine production, and may be associated with predisposition to infectious diseases. Some reports suggest that the cytokine gene polymorphisms can contribute to the susceptibility to brucellosis. The aim of this review is to find out any probable association of genetic polymorphisms of interleukin gene, transforming growth factor gene, tumor necrosis factor gene and other genes with brucellosis in terms of susceptibility to the disease or occurrence of focal complications. The study of this review finds that the inheritance of the above-mentioned gene polymorphisms and alleles are considered conferring susceptibility to brucellosis, and this review would provide the basis for further research and development about susceptibility to brucellosis.

Abstract: Some physical properties (such as lattice parameter, curie temperature, ac susceptibility) of Mg1-xZnxFe2O4 (where x = 0.3,0.4,0.5,0.6) ferrites have been studied. Magnesium Zinc Ferrites was synthesized by oxalate co-precipitation method at different synthesis temperature and characterized by X-ray diffraction and far IR absorption techniques, scanning Electron microscopy .The lattice parameter were computed. The X-ray diffraction studies reveal the formations of single phase cubic spinel structure.IR absorption bands are observed around 600 cm-1 and 400 cm-1 on the tetrahedral and octahedral sites respectively. Magnetization parameters such as saturation magnetization, and magnetic moment were calculated and the results are discussed with the help of the existing theories. Saturation magnetization was found to be in the range 2 emu/gm to 8.28 emu/gm when the samples were synthesized below 100°C. The variation of A.C. susceptibility with temperature shows the existence of super paramagnetic nature. The Curie temperature was determined from the measurement of the susceptibility verses temperature. The SEM micrograph shows the uniform distribution of the particles, the average size was estimated to be 0. 350 µm.

Abstract: In recent years, the growth of urban populations in hazardous areas has increased the impact of natural disasters in both developed and developing countries. The purpose of the current study is to assess the landslide susceptibility in Kalaleh township of Golestan province, Iran. In this study the Shannon’s entropy approach was applied. A total of 82 landslide locations were identified primarily from aerial photographs and field surveys. Then eighteen landslides conditioning factors were prepared in GIS. These landslide conditioning factors are: slope degree, slope aspect, altitude, plan curvature, profile curvature, tangential curvature, surface area ratio (SAR), lithology, land use, soil texture, distance from faults, distance from rivers, distance from roads, fault density, road density, topographic wetness index (TWI), stream power index (SPI), and sediment transport index (STI). Using these conditioning factors, landslide susceptibility index was calculated using Shannon’s entropy. For model validation, the results of the analyses were then compared with the field-verified landslide locations. Additionally, the receiver operating characteristics (ROC) curves for landslide susceptibility maps were drawn and the area under curve values was calculated. Verification results showed 82.15% accuracy. According to the results of the AUC (area under curve) evaluation, the map produced exhibits satisfactory properties.