DIP angle dependence on track formation sensitivity in antioxidant doped CR-39 plates

Recently, space radiation dosimetry measurements were made by passive and active detectors inside the Spacelab [STS-47 (FMPT): 300km, 57°, STS-65 (IML-2 mission): 300km, 28.5°]. The LET distributions obtained by antioxidant doped CR-39 inside the Spacelab were compared with those measured by the tissue equivalent proportional counter (TEPC) and the real time radiation monitoring device (RRMD) consisting of eight silicon detectors. While both distributions by CR-39 are in good agreement with those obtained by active detectors over the region of LET of several tens to 200 keV/μm, a significant difference in the LET region of smaller than several tens keV/μm is seen. It is considered to be caused by the dip angle dependence of track formation sensitivity in CR-39. The track formation sensitivity for different dip angle were measured for several high heavy energy ions. Using these results, the correction for the dip angle was made for the LET distribution. The corrected result is consistent with the results obtained by active detectors.     

Copula convergence theorems for tail events

Tail dependence is studied from a distributional point of view by means of appropriate copulae. We derive similar results to the famous Pickands–Balkema–de Haan Theorem of Extreme Value Theory. Under regularity conditions, it is shown that the Clayton copula plays among the family of archimedean copulae the role of the generalized Pareto distribution. The practical usefulness of the results is illustrated in the analysis of stock market data.     

pH-dependent conformational switching in 2,6-benzamidodiphenylacetylenes

The conformational equilibrium of a pH-dependent switch based on an intramolecularly H-bonded diphenylacetylene can be predictably biased by using electron-donating or -withdrawing groups. Furthermore, protonation of the electron-donating dimethylamino group converts it into an electron-withdrawing dimethylammonium cation with a concomitant switch in conformation.     

Temperature Dependence of the Viscosity and Conductivity of Mildly Functionalized and Non‐Functionalized [Tf2N]− Ionic Liquids

A series of bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) with classical as well as mildly functionalized cations was prepared and their viscosities and conductivities were determined as a function of the temperature. Both were analyzed with respect to Arrhenius, Litovitz and Vogel–Fulcher–Tammann (VFT) behaviors, as well as in the context of their molecular volume (V_m). Their viscosity and conductivity are highly correlated with V_m/T or related expressions (R²≥0.94). With the knowledge of V_m of new cations, these correlations allow the temperature‐dependent prediction of the viscosity and conductivity of hitherto unknown, non‐ or mildly functionalized ILs with low error bars (0.05 and 0.04 log units, respectively). The influence of the cation structure and mild functionalization on the physical properties was studied with systematically altered cations, in which V_m remained similar. The T_o parameter obtained from the VFT fits was compared to the experimental glass temperature (T_g) and the T_g/T_o ratio for each IL was calculated using both experimental values and Angell’s relationship. With Walden plots we investigated the IL ionicity and interpreted it in relation to the cation effects on the physical IL properties. We checked the validity of these V_m/T relations by also including the recently published variable temperature viscosity and conductivity data of the [Al(OR^F)₄]^? ILs with R^F=C(H)(CF₃)₂ (error bars for the prediction: 0.09 and 0.10 log units, respectively).     

正态变量相关情况下可靠性灵敏度分析的新方法

基于独立正态变量情况下可靠性灵敏度分析的线抽样法,提出了一种求解正态相关变量情况下可靠性灵敏度的新方法。在所提方法中,首先将正态相关变量等效变换为正态独立变量,然后利用线抽样方法独立完成等效独立变量情况下失效概率对独立变量的所有分布参数的灵敏度分析,最后依据等效变换前后变量分布参数之间的解析关系和复合函数求导公式,求得...     

Optimization of parameters for molecular dynamics simulation using smooth particle-mesh Ewald in GROMACS 4.5

Based on our critique of requirements for performing an efficient molecular dynamics simulation with the particle-mesh Ewald (PME) implementation in GROMACS 4.5, we present a computational tool to enable the discovery of parameters that produce a given accuracy in the PME approximation of the full electrostatics. Calculations on two parallel computers with different processor and communication structures showed that a given accuracy can be attained over a range of parameter space, and that the attributes of the hardware and simulation system control which parameter sets are optimal. This information can be used to find the fastest available PME parameter sets that achieve a given accuracy. We hope that this tool will stimulate future work to assess the impact of the quality of the PME approximation on simulation outcomes, particularly with regard to the trade-off between cost and scientific reliability in biomolecular applications.     

The density of interface states and their relaxation times in Au/Bi4Ti3O12/SiO2/n‐Si(MFIS) structures

Bismuth titanate (Bi₄Ti₃O₁₂) (BTO) thin films were fabricated on an n‐type Si substrate and annealed by rapid thermal annealing methods. The I‐V measurement shows that the device has properties of Schottky diode with the Φ_B0 of 0.76 eV, n of 2.42, and leakage current of about 10^?7 A at ? 8 V. The experimental C‐V‐f and G/w‐V‐f characteristics of metal‐ferroelectric‐insulator‐semiconductor (MFIS) structures show fairly large frequency dispersion especially at low frequencies due to interface states N_ss. The energy distribution of (N_ss) has been determined by using the high‐low frequency capacitance (C_HF? C_LF) and conductance method. The relaxation time (τ) of interface states was calculated from the conductance method. It has been shown that both the N_ss and relaxation time increase almost exponentially with bias, which activates traps located at deeper gap energies. Copyright © 2011 John Wiley & Sons, Ltd.     

Analytical approximations for speed-dependent spectral line profiles

Analytical approximate expressions for speed-dependent Rautian-Sobel'man, Voigt, and general line profiles, including spectral line mixing, were obtained. Systematic errors of the approximate profiles are within 0.7% for the mass ratios of perturbing and absorbing molecules m_b/m_a≤9. The calculation time of the approximate line profiles is much shorter than the time required for calculating exact expressions for the line profiles. An approximate analytical expression for the observable homogeneous line width was derived. A least-square fitting of the singlet methane absorption line centered at 6107.17 cm⁻¹ was performed, using the approximate line profiles obtained.     

The bivariate normal copula function is regularly varying

We derive the rate of decay of the tail dependence of the bivariate normal distribution and establish its link with regularly varying functions. This result is an initial step in explaining the discrepancy between a zero asymptotic tail dependence coefficient and mass in the tail of a joint distribution.     

Size-dependence of the anharmonicities in the vibrational potential of colloidal CdSe nanocrystals

We investigated multi-phonon processes in two types of CdSe nanocrystals, spherical quantum dots and nanorods by temperature-dependent Raman spectroscopy. We find the anharmonic constants relating to the two- and three-phonon decay channels to systematically change with changing nanocrystal size. The contributions from two-phonon processes decrease with decreasing diameter, while the contributions from higher-order processes increase. The anharmonicities in the vibrational potential increase due to the phonon confinement, and we did not find a shape dependence.