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The process of grain rotation with small initial misorientation angles in nanocrystalline materials is investigated by using the phase field crystal (PFC) method. Simulation results reproduce the grain rotation process of nanocrystalline grains and are consistent with the classical coupled motion theory excellently. The grain rotation with very small initial misorientations, which cannot be illustrated via the Frank formula because of the large elastic distortion in the grain, is reasonably described by the strain field analysis. It is also revealed that the significant elastic distortion induced by grain boundaries (GBs) determines the rotational dynamics; moreover, the movement of grain boundary dislocations (GBDs) plays a dominant role in the evolution of elastic distortions which results in the grain rotation.

The application of continuous wavelet transformation in the phase field crystal model has yielded excellent results for the crystal lattice orientation and grain boundaries with different misorientation angles [H.M. Singer, I. Singer, Phys. Rev. E 74 (2006) 031103]. However, we show here that the orientation map from this simple method cannot distinguish symmetric orientations using a single convolution template. By introducing additional rotational templates, the grain orientation can be uniquely visualized in two and three dimensions.

For a two-echelon supply chain system which consists of upstream node enterprises and downstream node enterprises, cooperation mechanism between bounded rational upstream and downstream nodes through collaborative establishment and implementation of food traceability system was modeled based on evolutionary game theory. The study shows that the probability of cooperation between both sides has a a negative correlation with the total cost of establishment and positive correlations with the probability of risk occurrence, the total excess income and reduction in risk loss from cooperation of both sides, and the excess income from the establishment of one side. Cost shared by both sides should be positively related to the excess income they obtaine. And there are an optimal coefficient of total excess income allocation and an optimal coefficient of reduction in risk loss allocation to maximize the probability of cooperation.

Using the phase-field crystal method, we investigated the bcc {1 0 1} vicinal surface growth from melts at the atomic scale with emphasis on the growth kinetics of two growth modes: step flow growth and island growth on terrace. Simulation results show that, for step flow growth, with the decrease of terrace width, the competition for feeding atoms between neighboring steps causes growth rate vs. step density to deviate from a linear relationship, and finally converge to a finite value. The step crystal direction also strongly influences the growth kinetics: vicinal surface with steps along the closest packed direction-[1 1 1] grows slower than that with [0 0 1] step. For island growth on terrace, the growth exponent of each layer in multi-layer island gradually transits from 1/2 for the top layer to 1/3 for the bottom layer, which demonstrates the transition from global diffusion controlled growth for top layer to surface diffusion controlled growth for bottom layer. The growth mechanism selection map with respect to terrace width and supersaturation is summarized and atom attaching rates of different growth mechanisms are also compared. (c) 2013 Elsevier B.V. All rights reserved.

Due to the large grain boundary (GB) volume fraction in nanocrystalline materials, interactions between GB and compositional domain boundary (CDB) play an important role in determining the nanoscale-modulated domain structures during spinodal decomposition. In the present paper, the phase field crystal model is employed to investigate the interactions between GB and CDB. Simulation results show that CDB coarsening can drive the GB migration and bring the impingement of particles with different orientations; the large volume fraction of GB can increase the dislocation volume fraction in CDBs but does not change its proportion in the whole defects number; the crossover point of the coarsening dynamic comes from the block effect of GB with large volume fraction.

This paper compares four different commutation strategies for a new monolithic dual-gate bidirectional IGBT (BD-IGBT) in matrix converters. A new variable-timing four-step commutation and an one-step commutation control strategies are proposed and compared with the conventional and the two-level four-step commutation methods reported previously. Operation modes and power losses of the BD-IGBT using these commutation strategies are analyzed with mixed-mode device/circuit simulation. The power loss and efficiency of a 13 kW three-phase to three-phase matrix converter are compared between the conventional combo switch and the new single-chip BD-IGBT implementations. It is found that the BD-IGBT, when using an optimal commutation strategy, offers significant advantages over the conventional IGBT/diode cell in terms of efficiency and cost.

This paper investigates the applicability and commutation strategy of a new monolithic dual-gate bidirectional IGBT (BD-IGBT) in matrix converters. Physics-based device model of the BD-IGBT is first developed and experimentally validated. Operation modes and power losses of the new BD-IGBT using an adapted four-step commutation control strategy are analyzed with mixed-mode device/circuit simulation. A new two-level gate control approach is proposed to maximize the benefit of the BD-IGBT with a considerably reduced conduction loss. The power loss, efficiency, and component cost of a 13 kW three-phase to three-phase matrix converter are compared between the conventional IGBT/diode combo switch and the new single-chip BD-IGBT implementations. It is found that the BD-IGBT implementation exhibits significant advantages over the conventional IGBT/diode cell in efficiency and cost in same matrix converter.

SIRT6has been demonstrated to exert protective effects on endothelial cells and is closely associated with lipid metabolism, glucose metabolism, and obesity, indicating an important role in the pathogenesis and progression of coronary artery disease (CAD). Nonetheless, the biological significance ofSIRT6variants on CAD is far to be elucidated. Here we aimed to investigate the influence ofSIRT6polymorphisms on individual susceptibility and severity of CAD. Multivariate logistic regression analysis exhibited no significant association between these five polymorphisms and CAD risk in the genotype and allele frequencies. However, we found that the rs352493 polymorphism inSIRT6exhibited a significant effect on the severity of CAD; C allele (χ2= 7.793, adjustedP=0.013) and the combined CC/CT genotypes (χ2= 5.609, adjustedP=0.031) presented the greater CAD severity. In addition, A allele (χ2= 5.208, adjustedP=0.046) and AA (χ2= 4.842, adjustedP=0.054) of rs3760908 were also associated with greater CAD severity in Chinese subjects. Our data provided the first evidence thatSIRT6tagSNPs rs352493 and rs3760908 play significant roles in the severity of CAD in Chinese Han subjects, which might be useful predictors of the severity of CAD.

lincRNA-p21 plays an important role in the pathogenesis and progression of coronary artery disease (CAD). To date, the biological significance of polymorphisms inlincRNA-p21on CAD risk remains unknown. Here we aimed to evaluate the influence oflincRNA-p21polymorphisms on individual susceptibility to CAD. Genotyping of four tagSNPs (rs9380586, rs4713998, rs6930083, and rs6931097) withinlincRNA-p21gene was performed in 615 CAD and 655 controls. The haplotype analysis showed that the haplotype G-A-A-G (rs9380586-rs4713998-rs6930083-rs6931097) was statistically significantly associated with the reduced risk for CAD (OR = 0.78,P= 0.023). Stratified analysis revealed that G-A-A-G haplotype was at a significantly lower risk for myocardial infarction (MI) (OR = 0.68,P= 0.010). We also found that haplotype G-A-A-G had a more pronounced decreased risk for premature CAD or MI subjects (OR = 0.67,P= 0.017 for premature CAD, and OR = 0.65,P= 0.041 for premature MI, resp.). Our data provide the first evidence that the G-A-A-G haplotype oflincRNA-p21is associated with decreased risk of CAD and MI, particularly among premature CAD/MI in the Chinese Han population. Further studies with more subjects and in diverse ethnic populations are warranted to clarify the general validity of our findings.

Using the phase-field crystal model, we investigate the orientation selection of the cubic dendrite growth at the atomic scale. Our simulation results reproduce how a face-centered cubic (fcc) octahedral nucleus and a body-centered cubic (bcc) truncated-rhombic dodecahedral nucleus choose the preferred growth direction and then evolve into the dendrite pattern. The interface energy anisotropy inherent in the fcc crystal structure leads to the fastest growth velocity in the directions. New {111} atomic layers prefer to nucleate at positions near the tips of the fcc octahedron, which leads to the directed growth of the fcc dendrite tips in the directions. A similar orientation selection process is also found during the early stage of bcc dendrite growth. The orientation selection regime obtained by phase-field crystal simulation is helpful for understanding the orientation selection processes of real dendrite growth. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

We introduce the Besov spaces B"p"@q^@W(S^d^-^1) of generalized smoothness on the sphere S^d^-^1, and obtain the representation theorem, an embedding theorem, and the characterization using a frame. We also study the Kolmogorov, linear and Gelfand widths of Besov classes BB"p"@q^@W(S^d^-^1) of generalized smoothness in L"q(S^d^-^1) for 1@?p,q@?~, and obtain their asymptotic orders.

The mechanism of formation of the large-dimension rare-earth(RE) inclusions in steels is discussed by TEM(Transmission Electron Microscope) taking steel 5CrNiMo with addition of RE as example. The two or several large-dimension RE inclusions come out independent nucleation which grow up into a 0.3~0.5 micron in length, then attract and integrate into the large-dimension with 1~5 micron in length. Though the dimension difference between the RE inclusions is varied, the shape is spherical or approximate spherical or elliptical, but no sharply corneous, because RE can promote the inclusion shape variation through metamorphism.

We investigate surface-enhanced Raman scattering(SERS) spectra of pyridine-A(n) (n = 2-8) complexes by density functional theory (DFT) and time-dependent DFT (TDDFT) methods. In simulated normal Raman scattering (NRS) spectra, profiles of pyridine-Ag-n (n = 2-8) complexes are analogical with that of isolated pyridine. Nevertheless, calculated pre-SERS spectra are strongly dependent on electronic transition states of new complexes. Wavelengths at 335 nm, 394.8 nm, 316.9 nm and 342.6 nm, which are nearly resonant with pure charge transfer excitation states, are adopted as incident light when simulating pre-SERS spectra for pyridine-Ag-n (n = 2-8) complexes, respectively. We obtain enhancement factors from 103 to 105 in pre-SERS spectra compared with corresponding NRS spectra. The obvious increase in Raman intensities mainly result from charge transfer resonance Raman enhancement. A charge difference densities (CDDs) methodology is adopted in describing chemical enhancement mechanism. This methodology aims at visualizing charge transfer from Ag-n (n = 2-8) clusters to pyridine on resonant electronic transition, which is one of the most direct evidences for chemical enhancement mechanism. (C) 2011 Elsevier B.V. All rights reserved.

The growth behavior of Ni 3 Al phase layer in the β/γ diffusion couple of Ni–Al binary system, including the shape evolution and growth kinetics, have been simulated by using the KKS multiphase field model. Simulation results indicate that, when Ni 3 Al layer growth is controlled completely by volume diffusion, it could be regarded as parabolic growth. However, if the fast grain boundary diffusion is taken into account, the growth rate of Ni 3 Al phase is accelerated, and the growth kinetics deviates from parabolic growth, which is consistent with experiments and other simulation results. Simulation results also demonstrate some details of shape evolution of grains, such as the uneven Ni 3 Al/γ and Ni 3 Al/β interfaces and the grain boundary migration of Ni 3 Al grains caused by fast grain boundary diffusion.

As one of the most attractive post-silicon power semiconductor devices, SiC bipolar junction transistor (BJT) has been studied intensively and commercialized in the past few years. However, SiC BJT has not been widely accepted in the market because of high driver loss in the on-state, which is induced by a relatively large constant base current in order to ensure its fully turning on. In this paper, a new proportional base driver for the SiC BJT is proposed in order to reduce its driver loss. It utilizes a silicon MOSFET as a variable resistor between the base driver and the base of the SiC BJT. The gate voltage of the silicon MOSFET decreases with the collector current of the SiC BJT via a Hall device, thus the on-state resistance of the MOSFET increases and the actual base driver current of the SiC BJT decreases. Comparing to the conventional SiC BJT driver, the proposed new proportional base driver can achieve the decrease of the base current with the decreasing of the collector current of SiC BJTs and has simple circuitry, resulting in the reduction of base driver loss. The simulation and experiment have verified that the proportional base driver of SiC BJT can reduce the driver loss by approximately 70% under the light load condition.

A modified phase-field-crystal (PFC) model is proposed to describe solid-liquid phase transitions by reconstructing the correlation function. The effects of fitting parameters of our modified PFC model on the bcc-liquid phase diagram, numerical stability, and solid-liquid interface properties during planar interface growth are examined carefully. The results indicate that the increase of the correlation function peak width at k=k(m) will enhance the stability of the ordered phase, while the increase of peak height at k=0 will narrow the two-phase coexistence region. The third-order term in the free-energy function and the short wave-length of the correlation function have significant influences on the numerical stability of the PFC model. During planar interface growth, the increase of peak width at k=k(m) will decrease the interface width and the velocity coefficient C, but increase the anisotropy of C and the interface free energy. Finally, the feasibility of the modified phase-field-crystal model is demonstrated with a numerical example of three-dimensional dendritic growth of a body-centered-cubic structure.

Background Hypercholesterolemia arising from abnormal lipid metabolism is one of the critical risk factors for coronary artery disease (CAD), however the roles of genetic variants in lipid metabolism-related genes on premature CAD (≤60 years old) development still require further investigation. We herein genotyped four single nucleotide polymorphisms (SNPs) in lipid metabolism-related genes (rs1132899 and rs5167 in APOC4, rs1801693 and rs7765781 in LPA), aimed to shed light on the influence of these SNPs on individual susceptibility to early-onset CAD. Methods Genotyping of the four SNPs (rs1132899, rs5167, rs1801693 and rs7765781) was performed in 224 premature CAD cases and 297 control subjects (≤60 years old) using polymerase chain reaction-ligation detection reaction (PCR–LDR) method. The association of these SNPs with premature CAD was performed with SPSS software. Results Multivariate logistic regression analysis showed that C allele (OR = 1.50, P = 0.027) and CC genotype (OR = 2.84, P = 0.022) of APOC4 rs1132899 were associated with increased premature CAD risk, while the other three SNPs had no significant effect. Further stratified analysis uncovered a more evident association with the risk of premature CAD among male subjects (C allele, OR = 1.65, and CC genotype, OR = 3.33). Conclusions Our data provides the first evidence that APOC4 rs1132899 polymorphism was associated with an increased risk of premature CAD in Chinese subjects, and the association was more significant among male subjects. Electronic supplementary material The online version of this article (doi:10.1186/s12944-015-0065-7) contains supplementary material, which is available to authorized users.

Two-dimensional materials with unique and excellent physical and chemical properties have attracted much attention in recent years. Among the two-dimensional materials, graphene or grapheme-like materials with honeycomb structure can be mainly prepared by the chemical vapor deposition (CVD) method. The key of this method is to select the substrates and control the nucleation and growth process of honeycomb structures. Graphene prepared by CVD contains many structure defects and grain boundaries, which mainly arise from nucleation process. However, the nucleation mechanism of graphene prepared by CVD method is not very clear. In addition, more than ten kinds of metal substrates can be used as substrate materials in CVD methods, such as Cu and Ni, which have nearly always face-centered cubic (FCC) structures and similar functions in the preparation process. In order to better describe the nucleation of graphene and understand the influences of metal substrates, we introduce the structural order parameter into the three-mode phase-field crystal model to distinguish the low-density gas phase from condensed phases. Nucleation processes of graphene on substrates with different symmetries are studied at an atomic scale by using the three-mode phase-field crystal model, which can simulate transitions between highly correlated condensed phases and low-density vapor phases. Simulation results indicate that no matter whether there is a substrate in the nucleation process, firstly gaseous atoms gather to form amorphous transitional clusters, and then amorphous transitional clusters gradually transform into ordered graphene crystals, with continuous accumulation of new gaseous atoms and position adjustment of atoms. In the nucleation process, five membered ring structures act as a transitional function. When grown on the substrate with a good geometric match with the honeycomb lattice, such as (111) plane of FCC metals, the graphene island has small structural defects. However, when grown without a substrate or on the substrate with a bad geometric match, such as (100) plane of FCC metals, the graphene island contains many structural defects and grain boundaries, which are not conducive to the preparation of high quality graphene. Compared with the (100) crystal plane of the tetragonal cell, the (110) crystal plane of the rectangular cell is favorable for the preparation of graphene single crystals with less defects. Therefore, the appropriate metal substrate can promote the nucleation process of graphene and reduce the formation of distortions and defects during the nucleation and growth of graphene.

By using the phase field crystal model, we simulate the morphological transition of the crystal growth of equilibrium crystal shape, dendrite, and spherical crystal shape. The relationship among growth morphology, velocity, and density distribution is investigated. The competition between interface energy anisotropy and interface kinetic anisotropy gives rise to the pattern selection of dendritic growth in the diffusion controlled regime under low-crystal-growth velocities. The trapping effect in density diffusion suppresses morphological instabilities under high-crystal-growth velocities, resulting in isotropic growth of spherical crystal. Finally, a morphological phase diagram of crystal growth is constructed as function of the phase field crystal model parameters.

Wireless Sensor Networks (WSNs) are widely used in various applications for tracking or surveillance purposes. Border security monitoring and terrorist attack prevention are just two of many crucial homeland security applications which rely upon WSN technologies. In these applications, a great amount of sensors powered by batteries are deployed in a particular region. They detect events, process and relay data to the sink node at the base station. Power conservation is critical to these sensors. In this paper, we propose a routing algorithm which separates the sensor nodes to several scheduling sets and keeps track of the energy level of each sensor. This algorithm balances power consumption among sensors, and therefore prolongs the network lifetime. Simulation results verify that our algorithm outperforms the EECCR algorithm proposed in [1].

Steady-state dendrite growth is controlled by the states of dendrite tips, thus the morphology and growth kinetics of dendrite tip have always been a highly-studied issue in the field of dendrite growth. A crucial problem is to find out the factors influencing the morphology of dendrite tip, and to clarify their working mechanism. Since dendrite tip is at micrometer or even atomic scale, interface energy may probably plays an important role during the formation and stabilization of dendrite tips. Investigations of this issue at atomic scale is of significant because it can help us to clearly observe the morphology evolution of dendrite tip fundamentally, and specifically reveal the relationship between interface energy anisotropy and dendrite tip morphology. We investigate growth kinetics and morphology of dendrite tips at atomic scale by using phase-field crystal simulation. Atomic scale steady-state dendrite tips are obtained at different interface energy anisotropy and growth driving force. It is shown that the morphology of the forefront of dendrite tip varies periodically with time, which is related to the behavior of atom attachment during the steady-state growth of dendrite tip. Moreover, we demonstrate that growth driving force determines the overall shape of dendrite tip, but exerts little influence on the morphology of the forefront of dendrite tip which actually is determined by interface energy anisotropy. The dendrite tip of high interface energy anisotropy often presents sharp shape which is in favour of the formation of dendrite tip. Nevertheless, the shape of dendrite tip approaches to circle with decreasing magnitude of interface energy anisotropy, indicating that it is more difficult for the formation of dendrite tip under the circumstance of lower interface energy anisotropy.