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Zirconia has many important phases with Zr coordination varying from six-fold in the orthorhombic phase to eight-fold in the cubic and tetragonal phases. Development of empirical potentials to describe these zirconia phases is an important but long-standing challenge, and it is a bottleneck for theoretical investigation of large zirconia structures. Here, instead of using the standard core—shell model, we developed a new potential for zirconia by combining the long-range Coulomb interaction and bond-order Tersoff model. The bond-order characteristic of the Tersoff potential enables it to be well suited to describe the zirconia phases with different coordination numbers. In particular, the complex monoclinic phase with two inequivalent oxygen atoms, which is difficult to describe with most existing empirical potentials, is well described by this newly developed potential. This potential provides reasonable predictions of most of the static and dynamic properties of various zirconia phases. Besides its clear physical essence, this potential is at least one order of magnitude faster than core—shell based potentials in molecular dynamics simulation. This is because it does not include an ultralight shell that requires an extremely small time step. We also provide potential scripts for the widely used simulation packages GULP and LAMMPS.

Quantitative risk assessment method based on information entropy: Because there was short effective assessment way for the risk level of the whole information system. I brought the information entropy into risk assessment of information security. The definition of risk degree was given first, which was the Likelihood estimate of probability and impact of risk, to scale risk degree of the whole information system. Since the evaluation on the probability and impact of risk were fuzzy, the risk factors were evaluated by means of fuzzy comprehensive evaluation method. For this method, the weight of each risk would be gained by entropy-weight coefficient; the subjective of expert assignment will be overcome. The risk degree will be gained by combining fuzzy comprehensive evaluation with information entropy, to measure off the risk degree of information system. In the paper I gave examples to show the application of this method.

Misfit strain is inevitable in various heterostructures like the graphene/MoS

Misfit strain is inevitable in various heterostructures like the graphene/MoS 2 van der Waals heterostructure. Although the misfit strain effect on electronic and other physical properties have been well studied, it is still unclear how will the misfit strain affect the performance of the nanomechanical resonator based on the graphene/MoS 2 heterostructure. By performing molecular dynamics simulations, we disclose a misfit strain-induced decoupling phenomenon between the graphene layer and the MoS 2 layer during the resonant oscillation of the heterostructure. A direct relationship between the misfit strain and the decoupling mechanism is successfully established through the retraction force analysis. We further suggest to use the graphene/MoS 2 /graphene sandwich heterostructure for the nanomechanical resonator application, which is able to prevent the misfit strain-related decoupling phenomenon. These results provide valuable information for the future application of the graphene/MoS 2 heterostructure in the nanomechanical resonator field.

We perform molecular dynamics simulations to investigate the energy dissipation of the resonant oscillation for the group IV monolayers of puckered configuration, in which the oscillation is driven with different actuation velocities. We find that, in the moderate actuation velocity regime, the nonlinear coupling between the resonant oscillation mode and other high-frequency modes will lead to the non-resonant motion of the system. For the larger actuation velocity, the effective strain generated during the resonant oscillating causes a structural transition from the puckered configuration into the planar configuration, which is a characteristic energy dissipation mechanism for the resonant oscillation of these group IV puckered monolayers. Our findings shed light on mechanical applications of the group IV monolayers in the nanomechanical resonator field.

The thermal stability and crystallization kinetics of isotactic polypropylene (iPP) and iPP/organomontmorillonite (organo-MMT) nanocomposites were investigated with differential scanning calorimetry and thermogravimetry. The incorporation of organo-MMT up to a concentration of 4 wt % did not affect the melting temperature of iPP but did increase the peak thermal degradation temperature by 60°C. The isothermal crystallization kinetics showed that the addition of organo-MMT increased the crystallization rate of iPP but reduced the isothermal Avrami exponent. The crystallization temperature of the nanocomposites measured with nonisothermal crystallization was higher than that of plain iPP, and this indicated an enhanced crystallization rate. The nonisothermal Avrami exponent, like the isothermal exponent, decreased with the addition of organo-MMT, and this suggested changes in the crystallite growth geometry. Subsequently, the tensile yield strength and the tensile modulus both increased, but the elongation at break and the notched Izod impact strength did not change significantly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3404–3415, 2003

To assess the efficacy and safety of 10-day sequential therapy for Helicobacter pylori (H.pylori) eradication in children.The databases of Cochrane Central Register of Controlled Trials (CENTRAL, 2013,N01), Medline, Embase, OVID, Chinese Biological Medicine database (CBMDisc), CNKI, Chinese VIP and WANFANG (all from 2000-2013) were searched. And manual searches were performed for the relevant journals and conference proceedings. Prospective, randomized controlled trials of 10-day sequential therapy for H.pylori eradication in children were selected. The systematic review was conducted with the method recommended by The Cochrane Collaboration.Fifteen trials with a total of 1348 patients were included for analysis. The meta-analysis showed: (1) H.pylori eradication rates: 10-day sequential therapy were superior to triple therapy (80.78% (521/645) vs 69.84% (491/703), OR 2.13, 95%CI: 1.62-2.80, P0.01). It was also superior to 7-day and 10-day standard triple therapy (86.03% (271/315) vs 73.77% (225/305), 79.04% (181/229) vs 65.19% (176/270); OR 2.23, 2.11; 95%CI:1.47-3.36, 1.37-3.24;both P0.01) . There were non-superior to 14-day standard triple therapy (73.97% (108/146) vs 70.31% (90/128), OR 1.87, 95%CI: 0.46-7.69, P = 0.38). (2) Adverse effect rate: adverse events were similar between sequential and standard triple therapies (P = 0.58).The 10-day sequential therapy may be a new effective and safe option in treatment of H.pylori infections in children.

Novel starlike C60-bonding polymers were synthesized by using the iniferter technique. The fullerene C60 with pendent N,N-diethyldithiocarbamate groups (C60–SR) was used as polyfunctional photoiniferter. The effects of UV-irradiation time and ambient temperature on the molecular weight of polymer were investigated. The photopolymerization with C60–SR proceeded via a living-radical mechanism, and gave soluble polyfunctional polymers (photoiniferters). Multiple polymer arms were attached to the C60 core and the polymers obtained by C60–SR could also be used as excellent crosslinking agents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1286–1290, 2001

Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB–HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB–HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by To = 0.75B + 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was Tp = 0.91B + 320, and the temperature at which degradation was completed was Tf = 1.00B + 325. In the thermal degradation of P(HB–HV) (70:30), To = 0.96B + 308, Tp = 0.99B + 320, and Tf = 1.09B + 325. In the thermal degradation of P(HB–HHx) (85:15), To = 1.11B + 305, Tp = 1.10B + 319, and Tf = 1.16B + 325. The derivative thermogravimetry curves of PHB, P(HB–HV), and P(HB–HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures To, Tp, and Tf relative to those of PHB by 3–12°C (measured at B = 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 90–98, 2001