Materials Literature
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Abstract Surface degradation of implanted poly(ether urethane)s was studied quantitatively with a micro‐ATR–FTIR technique. Substantial degradation was observed particularly in the soft segment at the α‐carbon adjacent to the ether linkage. The degradation caused changes in the concentration profiles of the soft‐segme…
Raman spectra of B ion-implanted glassy carbon (GC) and hydrogenated amorphous carbon (a-C:H) films have been measured as a function of polarization direction of the scattered light and excitation wavelength. Raman bands of GC implanted heavily with a fluence of more than 5\ifmmode\times\else\texttimes\fi{}${10}^{15}$…
This paper presents a light scattering study of the dynamics of concentrated solutions of nearly monodisperse (σ≊0.16) spherical micronetwork particles consisting of highly cross-linked polystyrene dissolved in carbon disulfide, i.e., a ‘‘good’’ solvent. Above volume fractions of φ=0.50 the intermediate scattering fun…
The self-diffusion coefficient of hydrogen in the dihydrides TiH x and YH x was investigated by neutron spectroscopy (1.59 < x < 2.09, 350 °C < T < 950 °C). The two hydrides differ in that hydrogen in TiH x occupies solely tetrahedral interstitial sites, whereas a small percentage (< 10%) of the hydrogen in YH x is al…
An electron-energy-loss (EELS) study has been carried out on polycrystalline Sn before and after room-temperature exposures of 100, 500, 1500, and 3500 L [1 Langmuir (L)=${10}^{\mathrm{\ensuremath{-}}6}$ Torr s] to ${\mathrm{O}}_{2}$ at low pressure (${10}^{\mathrm{\ensuremath{-}}6}$ Torr) and to ${\mathrm{O}}_{2}$ at…
Results are summarized of ion-scattering analysis of the surface structure obtained following deposition and annealing of ultrathin layers of Sn on Cu(111), Ni(111), and Pt(111). It is found that on each substrate, annealing to about 0.4 of the substrate melting temperature gives rise to a stable structure characteriz…
Abstract Chitin was isolated from prawn shells, and chitosan was prepared from it. The degree of N ‐deacetylation and the molecular weight were determined using IR spectroscopy and viscometry, respectively. A series of different modified chitosan membranes were prepared by blending with polyvinylpyrrolidone (PVP). The…
Abstract It has been found that carbon dioxide remarkably accelerates the absorption of many low molecular weight additives into a number of glassy polymers. This effect is due to the high diffusivity, solubility, and plasticizing action of compressed CO 2 in polymers. The transport of CO 2 and the effects of CO 2 pre…
Results of an ab initio density-functional study of interlayer binding in graphite are presented. We obtain good agreement with experimental results for the equilibrium c-axis lattice parameter, exfoliation energy, and uniaxial compressibility for this highly anisotropic material. We also present the calculated band s…
We have considered theoretically the polarization of the luminescence of small CdSe microcrystals due to the hexagonal structure of the lattice. We derive the energy spectrum and wave functions of holes in spherical microcrystals. It is shown that the value of the splitting between the A and B hole states in microcrys…
We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green's-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results are in excellent agreemen…
The dependences of the specific saturation magnetization sigma (C), magnetic ordering temperature T C (C), average hyperfine field H(C) and average isomer shift delta (C) on Si concentration are measured in crystalline Fe-Si alloys disordered by mechanical crushing. It is shown that topological disordering does not de…
We present a model for the injection of minority carriers into porous silicon films which results in visible dc electroluminescence. A thin interfacial dielectric region is postulated between the surface of the porous silicon layer and a transparent conductive oxide on the surface, which allows alignment of states bet…
The authors report a comparative study of the L 3 -M 45 M 45 Auger spectra of Cu, Cu 2 O and CuO. The large intensity of the uncorrelated two-hole band-like spectrum in the L 3 -M 45 M 45 Auger spectra of Cu 2 O and CuO and the spectral shapes for these transitions indicate strong Cu 3d-O 2p hybridization in the oxide…
Using a multiple light scattering technique and a stabilizing counterflow (i.e., a fluidized bed), we measured the average sedimentation velocity, its variance, and the short-time self-diffusion coefficient in a concentrated hard-sphere suspension. Many-body hydrodynamic interactions slow both the Brownian diffusion a…
In the above reference, we prove that certain quantum spin chains with quantumalgebra symmetry are integrable. Specifically, these are the quantum-algebra-invariant open chains associated with the affine Lie algebras A (1) 1, A(2) 2n, A(2) 2n−1, B(1) n, C (1) n, and D (1)
The radiation-induced absorption in erbium-doped optical fibres (EDfs) has been found to be strongly dependent on the fibre core composition. Implictions for erbium-doped fibre amplifier (EDFs) performance have been modelled, and compositional variations which may increase their radiation hardness have been tentativel…
The phenomenon of interfacial AC and DC breakdown is the subject of this paper. Two pieces of EPDM rubber were pressed together and a special jig was conceived so as to provoke arcing along the interface. The voltage at which breakdown occurred was measured and its dependence on the type of voltage (AC or DC), the int…
Many aspects of electrical tree growth can be simulated by a model which neglects the microscopic degradation processes involved and models only the overall form of the tree and its interaction with the material and the applied field. The simulated trees generated by the model, like real electrical trees, have a distr…
It is shown by dielectric resonance absorption at 60 GHz that there is a linear coupling of the electric field to the ground state of effective mass acceptors in Si reflecting the lower ${\mathit{T}}_{\mathit{d}}$ symmetry in the central portion of the ground-state wave function. The coupling increases strongly with i…