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71.
Chi Wang Yong‐Wen Cheng Yao‐Chung Hsu Tsang‐Lang Lin 《Journal of Polymer Science.Polymer Physics》2002,40(15):1626-1636
Lamellar morphology and thickness of syndiotactic polystyrene (sPS) samples melt‐crystallized at various temperatures were probed using transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS). In addition, the melting temperature and enthalpy of the crystallized samples were characterized with differential scanning calorimetry. Under appropriate thermal treatments, all the samples investigated in this study were crystallized into β′ crystal modification, as revealed by wide‐angle X‐ray diffraction. From the SAXS intensity profiles, a scattering peak (or shoulder) associated with lamellar features as well as the presence of anomalous scattering at the zero‐scattering vector were evidently observed. The peculiar zero‐angle scattering was successfully described by the Debye–Bueche model, and subtraction of its contribution from the raw intensity profiles was carried out to deduce the intensity profile merely associated with the lamellar feature. The lamellar thickness obtained from Lorentz‐corrected intensity profiles in this manner agrees with that measured from the TEM images, provided that the two‐phase model is applied. On the basis of the Gibbs–Thomson equation, the modest estimations of equilibrium melting temperature and the surface free energy of the fold lamellar surface are 292.7 ± 2.7 °C and 20.2 ± 2.6 erg/cm2, respectively, when lamellar thicknesses measured by TEM are applied. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1626–1636, 2002 相似文献
72.
A dual-wavelength-injection-locked (DWIL) Fabry-Perot (FP) laser is used as an all-optical wavelength converter and regenerator.Regenerated pulses have narrower pulse-width of 37ps.Power penalty and extinction-ratio improvement of 1.5dB and 4dB respectively were achieved. 相似文献
73.
McIntosh AB Hudan S Metelko CJ de Souza RT Charity RJ Sobotka LG Lynch WG Tsang MB 《Physical review letters》2007,99(13):132701
We examine the decay of the 3.03 MeV state of (8)Be evaporated from an excited projectilelike fragment following a peripheral heavy-ion collision. The relative energy of the daughter alpha particles exhibits a dependence on the decay angle of the (8)Be(*), indicative of a tidal effect. A comparison of the measured tidal effect with a model suggests a measurable nuclear proximity interaction. 相似文献
74.
Let Δ(x) and E(x) denote respectively the error terms in the summatory formula for the divisor function and in the mean square formula for ζ(s) on the critical line. We consider some general mean values for Δ(x) and E(x) and discover interesting differences between these two functions. In particular, this yields evidence that E(x) is more negative than Δ(x). 相似文献
75.
Wang B Tsang SW Zhang W Tao Y Wong MS 《Chemical communications (Cambridge, England)》2011,47(33):9471-9473
Two newly synthesized naphthodithiophene-based copolymers, PNB, exhibit a low optical bandgap of ~1.64 eV with which the solar cells fabricated from the blend of PNB and PC(71)BM afforded a power conversion efficiency of 5.3% with external quantum efficiency over 60% in a broad spectral range. 相似文献
76.
The thermal decomposition of 3,4-dihydro-2H-pyran (DHP, C5H8O) has been investigated by two methods: in shock waves with the laser-schlieren technique using mixtures of 5 and 10% DHP in krypton over 900–1500 K, 110–560 torr; in a flow tube having a reaction pressure 0.5 torr above atmospheric using the decomposition of allylethyl ether as an internal standard, and covering 663–773 K. The retro-Diels-Alder dissociation to the stable acrolein and ethylene is the dominant channel for all conditions. Precise rate constants (rms deviation of 10%) were obtained for this process over the indicated temperature ranges. Unimolecular falloff is evident in the shock-tube results, and RRKM calculations also predict a slight falloff at the lower temperatures. These RRKM calculations use a routine vibration model transition state and agree closely with the high-temperature data when 〈ΔE〉down is a fixed 400 cm?1. Arrhenius expressions for k∞ derived from the two measurements are in close accord and also consistent with most previous studies of this reaction. © 1995 John Wiley & Sons, Inc. 相似文献
77.
The time-dependent Navier–Stokes equations and the energy balance equation for an incompressible, constant property fluid in the Boussinesq approximation are solved by a least-squares finite element method based on a velocity–pressure–vorticity–temperature–heat-flux ( u –P–ω–T– q ) formulation discretized by backward finite differencing in time. The discretization scheme leads to the minimization of the residual in the l2-norm for each time step. Isoparametric bilinear quadrilateral elements and reduced integration are employed. Three examples, thermally driven cavity flow at Rayleigh numbers up to 106, lid-driven cavity flow at Reynolds numbers up to 104 and flow over a square obstacle at Reynolds number 200, are presented to validate the method. 相似文献
78.
We review experimental and theoretical studies devoted to extract information on the behaviour of the symmetry energy, in
density regions different from the normal value, with charge-asymmetric reactions at Fermi energies. In particular, we focus
on the analysis of fragmentation reactions and isotopic properties of the reaction products. Results concerning “isoscaling”
properties and the N/Z equilibration among the reaction partners in semi-peripheral reactions are also discussed. 相似文献
79.
A. Miller D. A. B. Miller M. Bensoussan J. M. Moison D. C. Haueisen D. A. Depatie P. W. Kruse M. A. Khan A. L. Smirl B. S. Wherrett T. F. Boggess G. P. Perryman D. S. Chemla P. W. Smith A. C. Gossard W. T. Tsang S. Chu P. Hu T. M. Jedju S. Y. Yuen P. A. Wolff V. Moloney F. A. Hopf H. M. Gibbs S. L. McCall D. L. Kaplan S. Ovadia J. V. Moloney D. F. Walls 《Applied physics. B, Lasers and optics》1982,28(2-3):92-101
80.