Infrared spectrum of poly(vinylidene fluoride)

Two crystalline forms (α and β) of poly(vinylidene fluoride) were studied by infrared spectroscopy. The spectral differences permitted the study of the transformation and the ratio of the two forms. The ordinary \documentclass{article}\pagestyle{empty}\begin{document}$ \vec G,\vec F $\end{document} matrix method was used to calculate the fundamental mode with a Urey-Bradley type potential field, and a preferred set of the force constants was obtained.     

Combinatorially homogeneous graphs

Gardiner classified ultrahomogeneous graphs and posed the problem of defining “combinatorial homogeneity”. Later, Ronse proved that homogeneous graphs are ultrahomogeneous by classifying such graphs. In this paper, we give a direct proof that (suitably defined) combinatorially homogeneous graphs are ultrahomogeneous. Also, we clasify combinatorially C-homogeneous graphs.     

Investigation on trap distribution and photoelectronic effect due to UV,IR and visible light excitation in self-activated zns crystals

Photoelectronic effects in IR sensitive ZnS crystals are found for IR, UV and visible light excitations. The transient rise characteristic of UV excited photoluminescence (UPL) saturates faster than UV produced photoconductivity (UPC). The UPC shows a typical S-shaped rise curve for any 365 run excitation irradiance and temperature. Simultaneously measured transient behaviors of IR induced photoconductivity (INP) and IR stimulated luminescence (STL) have a strong IR excitation intensity dependence for λ_IR = 2.5?4.6 microm. A unique phenomenon, quick rise followed by quick decay during the initial 20 msec, is found in INP before reaching final maximum but is not observed in STL. During UV steady irradiation, additional photoconductivity and luminescence are quickly induced by an abrupt IR excitation of 2.5 microm. Then, the photoconductivity reaches a new steady state level below UPC steady state. However, the luminescence sets the same UPL steady state level. This means that photoconductivity exhibits an IR optical quenching but not stimulation, while neither optical quenching nor stimulation is found in luminescence. It is also possible to quench the UPC response with visible light excitation at 570 nm. These observations support the previously reported discussion that IR absorbing impurity centers and shallow traps, including recombination (or luminescence) centers must be involved in IR stimulable ZnS crystals. They also indicate the presence of deep trap centers for E_T ≈ 2.18 eV, which have a strong role in slow UPC rise.     

Current-voltage characteristics of charge-ordered organic crystals

The current-voltage characteristics of layered organic crystals theta-(BEDT-TTF)2MZn(SCN)4 (M = Cs, Rb) follow the power law with a large exponent (e.g., 8.4 at 0.29 K for M = Cs) over a wide range of currents in the low-temperature insulating state. The power-law characteristics are attributed to electric field-induced unbinding of electron-hole pairs that are thermally excited in the background of the two-dimensional charge order. The magnitude of crossover electric fields from Ohmic to the power-law characteristics indicates that the electron-electron Coulomb interaction is significantly long-ranged: The screening length is greater than 10 molecule sites.     

Products of the triplet excited state produced in the radiolysis of liquid benzene

The radiation chemical yields of the products derived from the triplet excited state produced in the radiolysis of liquid benzene with gamma-rays, 10 MeV 4He ions, and 10 MeV 12C ions have been determined. Iodine scavenging techniques have been used to examine the formation and role of radicals, especially the H atom and phenyl radical. For all irradiation types examined here, the increase in hydrogen iodide yields with increasing iodine concentration matches the increase in iodobenzene yields. This agreement suggests that the benzene triplet excited state is the common precursor for the H atom and the phenyl radical. Pulse radiolysis studies in liquid benzene have determined the rate coefficients for the reactions of phenyl radicals with iodine and with the solvent benzene to be 9.3 x 10(9) M(-1) s(-1) and 3.1 x 10(5) M(-1) s(-1), respectively. Direct measurements of polymer formation, which refers to trimers (C18) and higher order compounds (>C18), in liquid benzene radiolysis using gamma-rays, 4He ions, and 12C ions at relatively high doses have been performed using gel permeation chromatography. The yields of trimers increase from gamma-rays to 12C ions due to the increased importance of intratrack radical-radical reactions that can be scavenged by the radical scavenging reactions of iodine. On the other hand, the >C18 product yields decrease from gamma-rays to 12C ions. The structure of the polymer consists of a partly saturated ring as determined by infrared and gas chromatography/mass spectrometry studies. A schematic representation for the radiolytic decomposition of the benzene triplet excited state is presented.     

The total mixed curvature of open curves in $$E^3$$

The total mixed curvature of a curve in \(E^3\) is defined as the integral of \(\sqrt{\kappa ^2+\tau ^2}\), where \(\kappa \) is the curvature and \(\tau \) is the torsion. The total mixed curvature is the length of the spherical curve defined by the principal normal vector field. We study the infimum of the total mixed curvature in a family of open curves whose endpoints and principal normal vectors at the endpoints are prescribed. In our previous works, we studied similar problems for the total absolute curvature, which is the length of the spherical curve defined by the unit tangent vector, and for the total absolute torsion, which is the length of the spherical curve defined by the binormal vector.     

High-resolution photoassociation spectroscopy of ultracold ytterbium atoms by using the intercombination transition

We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden 1S0 - 3P1 intercombination line. The rovibrational levels in the 0u+ state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of 174Yb and those of 176Yb, a d-wave shape resonance for 174Yb is strongly suggested.     

The Total Squared Curvature of Curves and Approximation by Piecewise Circular Curves

For a smooth curve in the Euclidean spaces, the total squared curvature is defined as the integral of the square of the curvature. If one takes three points on the curve which are close to one another, the reciprocal of the radius of the circle passing through those points approximates the curvature. We use this to approximate the total squared curvature and study its convergence rate.     

Percentile estimation based on the power-normal distribution

The authors propose several estimation methods for the confidence interval of the percentile of the power-normal distribution, which specifies the distribution of the observed values before Box–Cox transformation and assumes that transformed distribution is the truncated normal distribution. Their approaches are based on the delta method and the inverse transformation method. Then the finite sample performance of each estimation method is compared through a simulation, and it is shown that the performance of the inverse transformation method is superior to the delta method. A reparametrization method of the power-normal distribution, which is useful parameter setting tool in simulations, is suggested. The authors also investigate the asymptotic behavior of the coverage probability of the confidence interval of the percentile of the power-normal distribution in the case wherein the variance inflation of the MLE associated with the estimation of the transformation parameter of the power-normal distribution is ignored.     

Interaction of anti-aggregation agent dimethylethylammonium propane sulfonate with acidic fibroblast growth factor

Prevention of aggregation is critical for analyzing protein structure. Non-detergent sulfobetaines (NDSBs) are known to prevent protein aggregation, but the molecular mechanisms of their anti-aggregation effect are poorly understood. To elucidate the underlying mechanisms, we analyzed the effects of dimethylethylammonium propane sulfonate (NDSB-195) on acidic fibroblast growth factor (aFGF). NDSB-195 (0.5M) increased both aggregation and denaturation temperatures of aFGF by 4 degrees C. Chemical shift perturbation analyses indicated that many affected residues were located at the junction between a beta-strand (or 3(10)-helix) and a loop, irrespective of the chemical properties of the residue. The apparent dissociation constants of the interaction ranged from 0.04 to 3M, indicating weak interactions between NDSB and protein molecules.