Straight‐Chain Segment Length Distribution in Oriented Polyethylene as Revealed by LAM-Raman Spectroscopy

With the help of low-frequency Raman spectroscopy, the peculiarity of structural organization of oriented PE produced by multistage zone drawing of melt-crystallized films was studied. The draw ratios varied from DR=6 to 21 for PEI with M_η=8·10⁴ and from 3.5 to 5.7 for PEII with M_η≈10⁶.

The half widths (Δν) of all observed LAM bands were larger than 10–20 cm^?1. This means that the bands comprise a continuum of the overlapped elementary bands with Δν≈3 cm^?1 because of the wide straight–chain segments (SCS) length distribution. The length (L) of straight segments calculated from LAM-spectra, following a routine procedure, lies in the range from 7–8 to 60 nm.

Weight fractions G_MW of the SCS, as functions of their length, have a bell-like shape. Comparison of the SCS lengths with the value of the long periods (D) inferred from SAXS data for the same samples indicates that the lengths do not exceed 2D. The structural interpretation of the data obtained is given on the basis of microfibrillar models of oriented polymers. The peculiarity of the microfibrillar structure in PEI and PEII samples such as crystallite sizes and shapes and concentrations of inter- and intrafibrillar tie molecules, manifest themselves as the shape of G_MW (L) functions obtained for PE samples of various M_w and DR.     

The Diagonalization of Hamiltonian in XY Spin Chain with Dzyaloshinskii–Moriya and Three-Body Interactions

By the methods of Jordan–Wigner transformation and Bogolyubov transformation, in this paper, we diagonalized the Hamiltonian in one-dimensional Heisenberg spin chain model with Dzyaloshinskii–Moriya interactions and three-body interactions, and further analyze the effect of the Dzyaloshinskii–Moriya interaction and different three-body interactions on the Bogolyubov transformation and the energy spectrum of quantum spin chains. The results shows that only the energy spectrum but not the coefficients of the Bogolyubov transformation depends on DM interaction and one type of three-site exchange interaction. Another kind of three-body interaction not only can move the criticality region, but also can generate a new critical point.     

Hydrogen and Neutron Irradiation Induced Hardening in Vanadium Alloys

It is well known that vanadium alloy will face to strong neutron irradiation and hydrogen environments as a structural material in a fusion reactor. Some researches have reported that vanadium alloy took strongly hardening after an exposure to hydrogen environment and irradiation by neutron at a temperature lower than 400℃. The ductility of the alloy was lost largely, even entirely brittle fracture occurred sometimes in tension loading of the alloy. Therefore, it‘s to get the knowledge of the hardening mechanism and the fracture mechanical for the purpose to improve the performances of the alloy under the circumstances.     

Nanocavity Shrinkage and Preferential Amorphization during Irradiation in Silicon

We model the recent experimental results and demonstrate that the internal shrinkage of nanocavities in silicon is intrinsically associated with preferential amorphization as induced by self-ion irradiation. The results reveal novel thermodynamic nonequilibrium properties of such an open-volume nanostructure in condensed matter and also of covalently bound amorphous materials both at nanosize scale and during ultrafast interaction with energetic beam.     

Ground-State Entanglement and Mixture in an XXZ Spin Chain

We study the pairwise entanglement and mixture of a three-qubit XX Z spin chain in the ground state in the presence of an external magnetic field B. The effects of the magnetic field, the anisotropy and the temperature on the entanglement and mixture are considered, and entanglement versus the mixture of all the two-spin states is investigated. We find that the maximal entangled mixed state can be obtained in the considered system by controlling the magnetic field. Our results provide another way to generate maximally entangled mixed states.     

Charged Particle Motion in Temporal Chaotic and Spatiotemporal Chaotic Fields

We investigate charged particle motion in temporal chaotic and spatiotemporal chaotic fields.In its steady wave frame a few key modes of the solution of the driven/damped nonlinear wave equation are used as the field.It is found that in the spatiotemporal chaotic field the particle drifts relative to the steady wave,in contrast to that in the temporal chaotic field where the particle motion is localized in a trough of the wave field.The result is of significance for understanding stochastic acceleration of particles.     

The Anomalous Effect of Interface Traps on Generation Current in Lightly Doped Drain nMOSFET＇s

The anomalous phenomenon of generation current ICD in the lightly doped drain （LDD） nMOSFET measured under the drain bias VD-step mode is reported. We propose an assumption of activated （A） and frozen （F） traps for the VD-step mode： The A traps contributes to ICD while the F process can make them lose the roles as generation centers. The A and F regions can form the F-A region. The comparison of the F and A regions decides the role of the F-A region. The experiments confirm the assumption.     

The Split Property and the Symmetry Breaking¶of the Quantum Spin Chain

We consider the relationship between the symmetry breaking and the split property of pure states of quantum spin chains. We obtain a representation theoretic condition implying that the half-sided uniform mixing condition leads to symmetry breaking of translationally invariant pure states. This is a mathematical generalization of Dichotomy previously found by I. Affleck and E. Lieb and M. Aizenman and B. Nachtergaele for ground states of a special class of Hamiltonians. Received: 1 February 1999 / Accepted: 5 December 2000     

Subtraction of Spurious Centre-of-Mass Motion in Quark Delocalization and Colour Screening Model

The quark delocalization colour screening model provides an alternative approach for the NN intermediate range attraction, which is attributed to the σ meson exchange in the meson exchange and chiral quark model. However the quark delocalization induces the spurious centre-of-mass motion （CMM）. A method for subtracting the spurious CMM proposed before is applied to the new scattering calculation. The subtraction of the spurious CMM results in an additional NN attraction. The NN scattering data are refitted by a fine tune of the colour screening constant.     

The Solution of Dynamical Equation of Motion of IBM-Ⅱ in Continuous Variable Representation

In this article the solution of dynamical equation of motion of IBM-Ⅱ in continuous variable representation is discussed.With appropriate transformation and approximation,the on-phase part of system manifests the vibration-rotation mode and the off-phase part the 'scissor mode',ect.In the last section the energy spectrum of ¹⁵⁶Gd is calculated.The result can well reproduce the algebraic result of IBM-Ⅱ.     

Comparison of Cavities Formed in Single Crystalline and Polycrystalline α-SiC after H Implantation

Cavities and extended defects formed in single crystalline and polycrystalline α-SiC implanted with H+ions are compared.The samples are investigated by cross-sectional transmission electron microscopy.H₂ bubbles are formed during H implantation and H₂ molecules escape the sample to form cavities during thermal annealing at 1100℃.Microcracks and the extended defects prefer to nucleate in single crystalline α-SiC,but not polycrystalline α-Si C.Grain boundaries can account for...     

Motion of vortex lines and mutual friction in superfluid4He nearT λ

The motion of a single vortex line in superfluid⁴He nearT is studied within modelF. The linear response of the vortex-line velocityv _L to a homogeneous counterflowv _s –v _n is calculated up to lowest order of renormalized perturbation theory. The critical temperature dependence is taken into account via the renormalizationgroup theory. Non-asymptotic critical effects are found to be important. The results are generalized to describe collective vortex motion and mutual friction in rotating superfluid⁴He. The phenomenological mutual-friction coefficientsB andB of Hall and Vinen are determined without adjustment of parameters. ForB quantitative agreement with experiments nearT is found whereas forB the agreement is only semiquantiative.     

The Use of the Levenberg–Marquardt and Variable Projection Curve-Fitting Algorithm in Intravoxel Incoherent Motion Method for DW-MRI Data Analysis

The objective of this study was to evaluate the performances of different algorithms for diffusion parameters estimation in intravoxel incoherent motion method for diffusion-weighted magnetic resonance imaging (DW-MRI) data analysis. Traditionally, the method of non-linear least squares analysis by means of Levenberg–Marquardt algorithms has been used to estimate the parameters obtained from exponential decay data. In this study, we evaluated the Variable Projection curve-fitting algorithm and the performance of two non-linear regression methods when single and multiple starting points were used. Analysis was done on simulation data to which different amounts of Gaussian noise had been added. The performance of two non-linear regression methods was compared using the residual sum of squares and the number of failures in data fitting. We conclude that the VarPro algorithm is superior to the LM algorithm for curve fitting in intravoxel incoherent motion method for DW-MRI data analysis.     

Vacuum Fluctuations and Motion of a Charged Test Particle in a Cylindrical Spacetime

The effects of quantum electromagnetic fluctuations upon the motion of a test charged particle are examined in a cylindrical spacetime in which one spatial is compactified. The mean squared fluctuations in the velocity and position of the test particle are calculated. It is found that the random motion of the test particle will be anisotropic. The possible consequences for theories with extra compactified spatial dimensions are discussed.     

Traps in the Nanocomposite Layer of Silicon–Silicon Dioxide and Their Effect on the Luminescent Properties

Physics of the Solid State - The traps of charge carriers in thermal films of silicon dioxide and silicon dioxide with a nanocomposite layer consisting of silicon oxide and silicon nanocrystallites...     

Light Irradiation through Small Particles and Its Applications for Surface Nanostructuring in Near Field

We investigate the light scattering through small particles and its applications in nanostructuring, such as nanobumping, nanopatterning and dry laser cleaning. The theoretical calculation based on Mie theory provides an exact solution for sphere cavity resonance and plasmon resonance, which are two mechanisms for dielectric and metallic particles assisted surface nanostructuring in near field. The experimental results indicate that nanobumps on glass surface and subwavelength holes array on silicon surface can be formed without cracks with the self-assembly of 1 μm silica particle mask under laser irradiation. It is also found that the scattering wave by 40 nm gold particles can propagate 200 times away in terms of particle radius as recorded by photoresist under the UV light irradiation. Meanwhile, dry laser cleaning of 40nm gold particle on silicon wafer is demonstrated at plasmonic resonance frequency. The total cleaning efficiency is estimated to be 80%.     

The Motion of a Nonholonomic Chaplygin Sphere in a Magnetic Field,the Grioli Problem,and the Barnett–London Effect

Doklady Physics - In this paper, we consider the motion of a nonholonomic Chaplygin sphere on a plane in a constant magnetic field under the assumption that the sphere has dielectric and...     

Motion of charged particles in a NUTty Einstein–Maxwell spacetime and causality violation

We investigate the motion of electrically charged test particles in spacetimes with closed timelike curves, a subset of the black hole or wormhole Reissner–Nordström-NUT spacetimes without periodic identification of time. We show that, while in the wormhole case there are closed worldlines inside a potential well, the wordlines of initially distant charged observers moving under the action of the Lorentz force can never close or self-intersect. This means that for these observers causality is preserved, which is an instance of our weak chronology protection criterion.     

Influence of Femtosecond Laser Irradiation and Heat Treatment on Precipitation of Silver Nanoparticles in Glass

Silver nanoparticles were precipitated inside an Ag2O-doped glass by femtosecond laser irradiation and successive heat treatment. The influence of heat treatment temperature on the precipitation of silver nanoparticles was investigated. Absorption spectra show that the femtosecond laser irradiation results in an apparent decrease of the treatment temperature for the precipitation of Ag nanoparticles. We demonstrate the control of precipitation, dissolution and growth of silver nanoparticles inside glass by changing the heat treatment temperature of using further femtosecond laser irradiation.