In this study, we use the first-principle calculations of density functional theory with gradient generalized approximation of Wu–Cohen to investigate the doping effect of vanadium impurity on structural, electronic and magnetic properties of In1?xVxP and B1?xVxP alloys at various concentrations x = 0.0625, 0.125 and 0.25. Owing to the metallic nature of majority spin and semiconducting minority spin, the In1?xVxP compounds exhibit a half-metallic character with total magnetic moments of 2 μB, while the B1?xVxP has metallic nature for all concentrations. The results of exchange parameters revealed that exchange coupling between vanadium atoms and the conduction band is ferromagnetic, confirming the magnetic feature of In1?xVxP and B1?xVxP. From our findings, we have predicted that the In1?xVxP alloys seem to be potential materials for spintronics. 相似文献
Energy is a scarce resource in Wireless Sensor Networks (WSN). Some studies show that more than 70% of energy is consumed in data transmission in WSN. Since most of the time, the sensed information is redundant due to geographically collocated sensors, most of this energy can be saved through data aggregation. Furthermore, data aggregation improves bandwidth usage and reduces collisions due to interference. Unfortunately, while aggregation eliminates redundancy, it makes data integrity verification more complicated since the received data is unique. 相似文献
Different polyurethanes (PU) were synthesized from polycaprolactone diol, 1.6-hexamethylene diisocyanate and bis(2-hydroxyethyl)terephthalate,
using a two- and one-step methods providing regular and random distributions of starting monomers in the polyurethane chains.
Even with an identical molar monomer composition, the properties of obtained PU are different depending on the method of synthesis.
The chemical structure of PU was characterized by 1H and 13C NMR spectroscopy, as well as by FTIR and UV–Visible spectroscopy. The thermo-mechanical and hydrophilic properties of synthesized
PU were also studied demonstrating the influence of aromatic ring in the macromolecular chain. 相似文献
Finite element analysis (FEA) combined with the concepts of Linear Elastic fracture mechanics (LEFM) provides a practical and convenient means to study the fracture and crack growth of materials. A numerical analysis (FEM) of cracks was developed to derive the SIF for two different geometries, i.e., a rectangular plate with half circle-hole and central edge crack plate in tension loading conditions. The onset criterion of crack propagation is based on the stress intensity factor, which is the most important parameter that must be accurately estimated and facilitated by the singular element. Displacement extrapolation technique (DET) is employed, to obtain the stress intensity factors (SIFs) at crack tip. The fracture is modeled by the splitting node approach and the trajectory follows the successive linear extensions of each crack increment. These comprehensive tests are evaluated and compared with other relevant numerical and analytical results obtained by other researchers. 相似文献
We analyzed a lubricated journal plain bearing supporting heavy loaded rotary mill. During start-up operating, after the shaft is lifted by high external pressure lubricant, the speed of the shaft grows from 0 to the operating hydrodynamic speed when, suddenly after the first thirty seconds of shaft rotation, the pressure drops in one recess causing excessive damage to the pad bearing interface. The aim was to understand and provide some answers to the pressure drop in order to give an appropriate correction. Misalignment between the shaft and bearing surfaces was considered and analyzed in first part of the study. According to the obtained results the proposed correction is to use a suitable constant flow lubrication system which avoids the pressure to drop in recesses. A real application was made on a partial pad bearing supporting a heavy rotary cement mill localized at the cement plant of Chlef in Algeria.
In a previous study using transgenic mice ectopically expressing Hoxa2 during chondrogenesis, we associated the animal phenotype to human idiopathic proportionate short stature. Our analysis showed that this overall size reduction was correlated with a negative influence of Hoxa2 at the first step of endochondral ossification. However, the molecular pathways leading to such phenotype are still unknown. Using protein immunodetection and histological techniques comparing transgenic mice to controls, we show here that the persistent expression of Hoxa2 in chondrogenic territories provokes a general down-regulation of the main factors controlling the differentiation cascade, such as Bapx1, Bmp7, Bmpr1a, Ihh, Msx1, Pax9, Sox6, Sox9 and Wnt5a. These data confirm the impairment of chondrogenic differentiation by Hoxa2 overexpression. They also show a selective effect of Hoxa2 on endochondral ossification processes since Gdf5 and Gdf10, and Bmp4 or PthrP were up-regulated and unmodified, respectively. Since Hoxa2 deregulation in mice induces a proportionate short stature phenotype mimicking human idiopathic conditions, our results give an insight into understanding proportionate short stature pathogenesis by highlighting molecular factors whose combined deregulation may be involved in such a disease. 相似文献
The high-temperature corrosion (700–1000°C) kinetics and processes in sulfur vapor and hydrogen sulfide were investigated for ferritic steels containing Cr and Al. Observation and analysis of the reaction curves obtained allowed the various corrosion steps to be clarified. Formation of compact, protective layers, at either the alloy-sulfide or at the sulfide-gas interface, occurred in the early stages of reaction and subsequently, most of the layers formed were microcrystalline and porous. The influence of the system parameters, i.e., temperature, pressure of the sulfidizing agent, and alloy composition, is reported in this paper. 相似文献