Initial stage of fiber structure development in the continuous drawing of poly(ethylene terephthalate)

The initial stage of fiber structure development in the continuous neck‐drawing of amorphous poly(ethylene terephthalate) fibers was analyzed by in situ wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, and fiber temperature measurements. The time error of the measurements (<600 μs) was obtained by synchrotron X‐ray source and laser irradiation heating. A highly ordered fibrillar‐shaped two‐dimensional (smectic‐like) structure was found to be formed less than 1 ms after necking. By analyzing its (001′) and (002′) diffractions, the length of the structure 60–70 nm were obtained. A three‐dimensionally ordered triclinic crystal began to form with the vanishing of the structure around 1 ms after necking. The amount and size of the crystal were almost saturated within several milliseconds of necking, during which time a mainly exothermic heat of crystallization was also observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2126–2142, 2008     

Carotenoids extraction from Japanese persimmon (Hachiya-kaki) peels by supercritical CO(2) with ethanol.

The extraction of carotenoids from Japanese persimmon peels by supercritical fluid extraction (SFE), of which the solvent was CO(2), was performed. In order to enhance the yield and selectivity of the extraction, some portion of ethanol (5 - 20 mol%) was added as an entrainer. The extraction temperature ranged from 313 to 353 K and the pressure was 30 MPa. The effect of temperature on the extraction yield of carotenoids was investigated at 10 mol% of the ethanol concentration in the extraction solvent, and a suitable temperature was found to be 333 K among the temperatures studied with respect to the carotenoid yield. With increasing the entrainer amount from 0 to 10 mol% at a constant temperature (333 K), the carotenoid yield in the extraction was improved, whereas the selectivity of the extracted carotenoids was drastically depressed. We also conducted qualitative and quantitative analyses for the carotenoid components in the extract by HPLC, and analyzed the extraction behavior of each individual carotenoid (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin). The selectivity of each carotenoid changed with the elapsed time and its time evolution was dependent on the carotenoid component, indicating that the location profile and the content can be important factors to understand the SFE behavior of each carotenoid in persimmon peels.     

Impedance spectra analysis of thermoresponsive poly(acryloyl‐L‐proline methyl ester) gel membrane in LiCl solution

Impedance spectra analysis of a thermoresponsive poly(acryloyl‐L ‐proline methyl ester) (poly(A‐ProOMe)) hydrogel membranes in an aqueous solution of LiCl was carried out using a simple equivalent model. The hydrogel membrane was synthesized by γ‐radiation‐induced polymerization and crosslinking of A‐ProOMe monomer aqueous solution in a glass‐cast. By means of the impedance spectra analysis, a novel method for the calculation of the ionic conductivity of the hydrogel membranes in LiCl solution was proposed. The calculated ionic conductivity was in agreement with the determined value. In addition, effects of temperature and LiCl concentration on the impedance spectra and ionic conductivity of the gel membrane were analyzed. Results indicated that the impedance spectra analysis is a very useful tool for evaluating the electric properties of gel membranes in an electrolyte solution. The poly (A‐ProOMe) gel membrane in 1.0 M LiCl solution showed a high ionic conductivity of about 0.2 S/cm at 14 °C. The temperature‐dependence of the ionic conductivity was a complex nonlinear form due to the volume phase transition of the thermoresponsive poly(A‐ProOMe) gel membrane, and the volume phase transition temperature appeared to be decreased with the increase in the LiCl concentration. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2843–2851, 2005     

Theory for the effect of the tip–surface interaction potential on atomic resolution in forced vibration system of noncontact AFM

We present a perturbation theory which enables us to understand the physics of the cantilever-forced vibration in noncontact atomic-force microscopy (nc-AFM). Analytical expressions of the resonance curve and frequency shift are given. This theory is applied to the model system with a van der Waals tip–surface interaction potential. Based on this case study, it is elucidated how the resonance frequency shift is analytically described by an integral of the tip–surface interaction force. Then nc-AFM image of Si(111) 7×7 surface is calculated by the present theory. It is examined that this theory works as an algorithm for nc-AFM image simulator.     

Global smooth solutions of IBVP to nonlinear equation of suspended string

We shall consider IBVP to a nonlinear equation of suspended string with uniform density to which a nonlinear time-independent outer force works. The nonlinear term is smooth but not monotone. We shall show that IBVP has a unique time-global smooth solution. The regularity of the solutions shall be also studied.     

A model for the temperature dependence of the viscosity in Cu–As–Se system

The microscopic bonding behavior of amorphous Cu_x(As₂Se₃)_1?x (x = 0.00, 0.01, 0.05, 0.10 and 0.20) is studied from the point of view of the viscosity. The model used in this analysis describes the temperature dependence of the viscosity in terms of the mean bond strength E₀, the mean coordination number Z₀, and their fluctuations ΔE, ΔZ of the structural units that form the melt. The model reproduces quite well the temperature dependence of the viscosity of Cu_x(As₂Se₃)_1?x observed experimentally. According to the theory, the fragility of the system increases as the fluctuation of the total bond strength increases. It is shown that the viscous flow is accompanied by the cooperative movements of the structural units and occurs by breaking selectively the weaker parts of the bonds between the structural units. This notion is related to the concept of Cooperatively Rearranging Region (CRR) in the theory of Adam–Gibbs. By analyzing the model, the fluctuation of the total bond strength in Cu–As–Se system is evaluated quantitatively, and the composition dependence of the fragility is discussed in terms of bond strength and the coordination number between the structural units. The analysis suggests that in the Cu_x(As₂Se₃)_1?x system, there must be a strong composition dependence in the bond strength and a weak composition dependence in the fragility and coordination number fluctuation.     

Analysis of heat conduction in a rarefied gas at rest with a temperature jump at the boundary by consistent-order extended thermodynamics

In the context of the first- and second-order theories of consistent-order extended thermodynamics, a systematic approach is established for analyzing the temperature jump at the boundary through studying one-dimensional stationary heat conduction in a rarefied gas at rest. Thereby an approach to the free boundary-value problem in general is explored. Boundary values of temperature are assumed to be in the form of power expansion with respect to the Knudsen number, based on which analytical expressions of the temperature jump aswell as entropy production at the boundary are derived explicitly. Dependencies of these two boundary quantities on both the Knudsen number and accommodation factor are also extensively discussed. The present analysis is expected to be the basis for the study of higher-order theories of consistent-order extended thermodynamics.      

Tetragonal SmBa2Cu3O7−x [x = 0.74 (4)]

Crystals of the title compound, samarium barium copper oxide, were prepared by a modified top‐seeded solution‐growth method. The crystals thus prepared showed no superconductivity down to 4.2 K. A careful examination showed that the structure closely resembles that of tetragonal YBCO, and there is no atom mixing at the Ba or other sites, within experimental accuracy. A bond‐valence‐sum calculation at the Ba site also indicated the absence of Sm. Each site is fully occupied by a single atom, except for the oxy­gen site in the basal plane of the CuO₆ octahedron. The occupancy of this oxy­gen site is significantly reduced [0.13 (2)], as is commonly observed in the 123 system. The atomic displacement parameters of the atoms in the CuO₂ plane, as well as of the Sm atom, are very small, indicating that two equivalent CuO₂ planes tightly sandwich the Sm atom.     

纳米孔径核孔膜的制备研究

高能硫、氪、氙离子轰击聚酯(PET)和聚碳酸酯(PC)膜后,对样品进行陈化和紫外线照射敏化.用电导法着重研究蚀刻条件对样品的归一化径迹蚀刻速率(灵敏度)的影响,结果表明优化条件下灵敏度较通用条件下提高约2倍,PET的灵敏度可达1000,PC的灵敏度可达2000,可以用于制备纳米孔径核孔膜.核孔膜中填充的铜纳米线的电镜照片显示出纳米线最小直径为20nm.用电导法计算纳米孔的孔径,该值与纳米线直径的电镜测量值在孔径大于30nm时符合良好.     

Electronic transmission of three-terminal pyrene molecular bridge

This paper investigates theoretically the electronic transmission spectra of the three terminal pyrene molecular bridge and the quantum current distribution on each bond by the tight-binding model based on nonequilibrium Green's function and the quantum current density approach, in which one π molecular orbital is taken into account per carbon atom when the energy levels and HOMO-LUMO gap are obtained. The transmission spectra show that the electronic transmission of the three terminal pyrene molecular bridge depends obviously on the incident electronic energy and the pyrene eigenenergy. The symmetrical and oscillation properties of the transmission spectra are illustrated. A novel plus-minus energy switching function is found. The quantum current distribution shows that the loop currents inside the pyrene are induced, and some bond currents are much larger than the input and the output currents. The reasons why the loop currents and the larger bond currents are induced are the phase difference of the atomic orbits and the degeneracy of the molecular orbits. The calculations illustrate that the quantum current distributions are in good agreement with Kirchhoff quantum current conservation law.