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In this paper, two kinds of coatings (iron-based and cobalt-based) were successfully prepared on the surface of AISI 304 stainless steel using laser cladding technology as substitute materials with excellent wear resistance and corrosion resistance, respectively. Subsequently, the phase composition, microstructure, crystallographic texture, microhardness distribution, wear behavior and corrosion behaviour of the two coatings were investigated. The results showed that the iron-based coating mainly composed of α-Fe and Cr23C6 phases, while the cobalt-based coating mainly composed of γ-Co and Cr23C6. There was no obvious texture in the two coatings, and the grain orientation showed a random characteristic. The grain size of iron-based coatings is greatly smaller than that of cobalt-based coatings. The average microhardness of the iron-based and cobalt-based coatings is 704 HV and 502 HV. The simultaneous effect of fine grain strengthening and second phase strengthening ensures high wear resistance of the iron-based coating. The combination of Cr-rich passive film and fine dispersed carbides ensures high corrosion resistance of the cobalt-based coating. [ABSTRACT FROM AUTHOR]

An investigation was designed to research the effect of molybdenum (Mo) content on the microstructure and properties of novel ferritic stainless steel (FSS) fabricated by laser melting deposition (LMD). In this study, the stainless steel specimens with different Mo content were manufactured using LMD and the microstructures, the microhardness, wear resistance and corrosion resistance of the as-deposited specimens were evaluated. Experimental results demonstrated that the phase composition of the specimens had no change and consisted of α-Fe and carbide M7C3 phase. The typical dendrite and interdendrite structures were observed, and the grains are obviously refined with the increase of Mo element. The microhardness value of as-deposited specimens increased from 643 to 803 HV, and the specific wear rate was reduced from 1.14 × 10−5 to 5.90 × 10−6 mm3/Nm, correspondingly one order of magnitude reduction, which verified that the wear resistance was obviously improved. The corrosion current density of FSS-Mo is two orders of magnitude lower than that of FSS, and it shows better impedance parameters, indicating that the addition of Mo can effectively improve the electrochemical corrosion performance of materials. [ABSTRACT FROM AUTHOR]

The management of nuclear wastes has long been a problem that hinders the sustainable and clean utilization of nuclear energy since the advent of nuclear power. These nuclear wastes include minor actinides (MAs: 237Np, 241Am, 243Am, 244Cm and 245Cm) and long-lived fission products (LLFPs: 79Se, 93Zr, 99Tc, 107Pd, 129I and 135Cs), and yet are hard to be handled. In this work, we propose a scheme that can transmute almost all the MAs and LLFPs with a lead-cooled fast reactor (LFR). In this scheme, the MAs and the LLFPs are loaded to the fuel assembly and the blanket assembly for transmutation, respectively. In order to study the effect of MAs loading on the operation of the core, the neutron flux distribution, spectra, and the keff are further compared with and without MAs loading. Then the LLFPs composition is optimized and the support ratio is obtained to be 1.22 for 237Np, 1.63 for 241Am, 1.27 for 243Am, 1.32 for 79Se, 1.53 for 99Tc, 1.02 for 107Pd, and 1.12 for 129I, respectively, indicating that a self-sustained transmutation can be achieved. Accordingly, the transmutation rate of these nuclides was 13.07%/y for 237Np, 15.18%/y for 241Am, 13.34%/y for 243Am, 0.58%/y for 79Se, 0.92%/y for 99Tc, 1.17%/y for 107Pd, 0.56%/y for 129I. Our results show that a lead-cooled fast reactor can be potentially used to manage nuclear wastes with high levels of long-lived radioactivity. [ABSTRACT FROM AUTHOR]

Disposal of long-lived fission products (LLFPs) produced in reactors has been paid a lot attention for sustainable and clean nuclear energy. Although a few transmutation means have been proposed to address this issue, there are still scientific and/or engineering challenges to achieve efficient transmutation of LLFPs. In this study, we propose a novel concept of advanced nuclear energy system (ANES) for transmuting LLFPs efficiently without isotopic separation. The ANES comprises intense photoneutron source (PNS) and subcritical reactor, which consist of lead–bismuth (Pb-Bi) layer, beryllium (Be) layer, and fuel, LLFPs and shield assemblies. The PNS is produced by bombarding radioactive cesium and iodine target with a laser-Compton scattering (LCS) γ-ray beam. We investigate the effect of the ANES system layout on transmutation efficiency by Monte Carlo simulations. It is found that a proper combination of the Pb-Bi layer and the Be layer can increase the utilization efficiency of the PNS by a factor of ~ 10, which helps to decrease by almost the same factor the LCS γ-beam intensity required for driving the ANES. Supposing that the ANES operates over 20 years at a normal thermal power of 500 MWt, five LLFPs including 99Tc, 129I, 107Pd, 137Cs and 79Se could be transmuted by more than 30%. Their effective half-lives thus decrease drastically from ~ 106 to less than 102 years. It is suggested that this successful implementation of the ANES paves the avenue towards practical transmutation of LLFPs without isotopic separation. [ABSTRACT FROM AUTHOR]

The gearbox is designed with the static strength design theory. However, it cannot accurately reflect the dynamic characteristics of its components under different task conditions, and the limitations of traditional measuring methods and testing means, make it very difficult to study the reliability and life prediction of the components of the gearbox at random loads, resulting in a large gap between the actual and design lives, which seriously affects the gearbox reliability. The multibody kinetics simulation method is used to simulate the gearbox kinetics in different gears of a test site, and the alternating load of the gearbox main shaft is obtained. Based on MSC.Patran software, the fatigue life prediction for the gearbox is investigated; the optimal design of gearbox gears is studied to provide important data for improving the gearbox reliability. [ABSTRACT FROM AUTHOR]

The transmission synchronizer is an important variable speed synchronization mechanism of a vehicle. Since accurate and feasible working load data at the design stage of the synchronizer are lacking, the design loads are taken to be static rather than actual working ones, resulting in a high failure rate of the synchronizer in service, which seriously affects the reliability of the whole transmission. The virtual prototype model of a transmission synchronizer is presented. The working load-effected fatigue life of a synchronizer pin is calculated with MSC.Patran software. The failure mechanism of the synchronizer pin is analyzed to predict its fatigue life under complicated working conditions. It provides an important theoretical basis for the optimum design of synchronizer mechanism parameters and reliable transmission design, which is of great practical significance. [ABSTRACT FROM AUTHOR]

Based on the state-of-the art methods of gas turbine cascade heat transfer assessment, a theoretical model of the two-dimensional air turbine cascade is proposed, wherein gas flows past the turbine blade profile. The velocity, temperature, and pressure fields, as well as the heat transfer distribution along the pressure and suction surfaces, the leading and trailing edges of the turbine blade were computed via FLUENT software at different pressure ratios. This permitted of studying the heat transfer evolution at different pressure ratios in the same position and at the same pressure ratio in different positions. [ABSTRACT FROM AUTHOR]

The hypothesis of niche differentiation with respect to resources is considered to be one of the most influential explanations for the maintenance of species diversity. The hypothesis has been examined extensively by testing its prediction of species-habitat association, which posits that the spatial distribution of species is highly correlated with environmental variables. However, we argue that widespread evidence of the species-habitat association lacks adequate rigor to justify the niche differentiation hypothesis. In this study, we tested whether and to what extent the observed species-habitat association could be caused by ecological processes other than niche differentiation, in a 20-ha subtropical forest plot. The niche differentiation hypothesis was evaluated by testing the species-habitat association and performing a cross-evaluation of the habitat-diversity expectation, which posits that a strong positive correlation exists between species diversity and habitat complexity. Failure to support the habitat-diversity expectation would at a minimum indicate that the niche differentiation hypothesis might not be the main underlying process of species distribution, despite prevalence of the species-habitat association in the same plot. Our analysis revealed that distributions of most species (86.11%) in the plot were significantly associated with at least one of eight topographical and soil nutrient variables. However, there was almost no significant positive correlation between species diversity and habitat complexity at various spatial scales in the same plot. The results indicate that additional caution is warranted when interpreting the species-habitat association from the niche differentiation perspective. A significant species-habitat association indicates only a species' habitat preference. The association may reveal nothing about interspecific differences in habitat preference, which is a requirement of the niche differentiation hypothesis. [ABSTRACT FROM AUTHOR]

In this study, which is a continuation of our earlier work, the effect of double-atom vacancy defects (DAVD) on the elastic properties of single-layered graphene sheets (SLGS)-polymer nanocomposites is assessed by the multiscale modeling. According to the latter approach, the polymer matrix is modeled by finite element approach, while the SLGS and interphase layer are simulated at the atomistic scale by the molecular structural mechanics approach. In view of the Lennard-Jones potential concept, it is assumed that the SLGS and polymer matrix are related by van der Waals reciprocity. The fact that the elastic modulus of a polymer with 5% volume fraction of SLGS is increased by 17 times is demonstrated by numerous simulation results. It is also shown that the elastic modulus of SLGS-polymer nanocomposites with DAVDs is deteriorated with an increase in the number of DAVDs and improved with the increased volume fraction of SLGS. [ABSTRACT FROM AUTHOR]

Lead magnesium niobate-lead titanate (PMN-PT) ceramic powder and Poly[VinyliDeneFluoride-co-TriFluoroEthylene] (P[VDF-TrFE]) have been used to fabricate 0-3 composites thick films on ITO substrates by tape casting. The phase structure and grain size of PMN-PT were analyzed by XRD and SEM. The distribution of ceramic powder in polymer matrix was characterized by SEM. In order to find out the optimal poling temperature, dielectric-temperature spectrums of the composite films were measured to calculate the electric field applied to the ceramic phase (E). Finally, PMN-PT/P[VDF-TrFE] composite films were polarized by one-step polarization under optimized polarization temperature and their pyroelectric constant were compared with these of samples poled using conventional two-step polarization method. The results showed that the pyroelectric coefficient increases to 58.6 μC m K at a ceramic mass fraction of 55% at the optimized polarizing temperature 110 °C. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have attracted great interest in cancer therapy owing to their tumor-oriented homing capacity and the feasibility of autologous transplantation. Currently, pancreatic cancer patients face a very poor prognosis, primarily due to the lack of therapeutic strategies with an effective degree of specificity. Anticancer gene-engineered MSCs specifically target tumor sites and can produce anticancer agents locally and constantly. This study was performed to characterize pancreas-derived MSCs and investigate the effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-engineered MSCs on pancreatic cancer cells under different culture conditions. Pancreas-derived MSCs exhibited positive expression on CD44, CD73, CD95, CD105, negative on CD34 and differentiated into adipogenic and osteogenic cells. TRAIL expression was assessed by both enzyme-linked immunosorbent assay and western blot analysis. Different patterns of TRAIL receptor expression were observed on the pancreatic cancer cell lines, including PANC1, HP62, ASPC1, TRM6 and BXPC3. Cell viability was assessed using a real-time monitoring system. Pancreatic cancer cell death was proportionally related to conditioned media from MSCnsTRAIL and MSCstTRAIL. The results suggest that MSCs exhibit intrinsic inhibition of pancreatic cancer cells and that this effect can be potentiated by TRAIL-transfection on death receptor-bearing cell types. [ABSTRACT FROM AUTHOR]

BaCO and anatase-type TiO were adopted as initial materials to prepare BaTiO powder by the solid-state reaction method at a heating rate of 350°C/h. The electron paramagnetic resonance (EPR) technique was employed to monitor the formation of BaTiO. TiO showed a series of complicated EPR signals associated primarily with Fe impurities. The formation of BaTiO can be monitored in terms of the evolution of EPR signals associated with Fe impurities with calcination and measurement temperatures. The activation of the g = 2.004 signal above the Curie point of BaTiO and the disappearance of the other EPR signals in the BaCO/TiO mixture at room temperature are characteristic of the formation of BaTiO. [ABSTRACT FROM AUTHOR]

The equilibrium structures, electronic properties of bimetallic Ti1-4M (M=V, Fe, Ni) clusters are investigated by using the density functional method within generalized gradient approximation in conjunction with the valence basis set. Considering the spin multiplicity effect, the geometries with different spins are optimized to find the ground states. For the ground states, the natural bonding orbital analysis (NBO) is performed and shows that the 4s electrons always transfer to the 3d orbital in the bonding atoms so that 4s and 3d orbitals hybridize with each other. The electron transfers from Ti atoms to the ‘impurity’ atoms (V, Fe, and Ni) are also found. The two kinds of electron transfer mechanisms are considered to be the contributor for the stabilities of the studied clusters. The Wiberg bond order and AIM (atoms in molecules) analyses indicate that the relative stabilities of chemical bonds are: $\text{Ti-V/Ti-Fe} > \text{Ti-Ti} > \text{Ti-Ni}$. The spin magnetic moments are found to be mostly located at Ti atoms. Several clusters like Ti2V, Ti3V, Ti3Ni and Ti4Ni present the high moments. [ABSTRACT FROM AUTHOR]