Materials Literature
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Abstract Degradation is an essential factor in polymer biocompatibility. The physiological environment of the human body can be aggressive to polymers. Most implanted polymers suffer degradation and the kinetics and mechanisms of the processes can be significantly affected by various biologically active species, espec…
Abstract The measurement of physical properties of thermoplastic natural rubber (TPNR) of NR–HDPE blends have been made at various compositions of high‐density polyethylene (HDPE). The tensile properties and hardness of TPNR improve significantly with the addition of liquid natural rubber (LNR) to the blend. The degre…
The absolute stereochemical courses of cis,cis-muconate lactonizing enzyme (MLE;EC 5.5.1.1) from Trichosporon cutaneum (TcMLE) and chloromuconate cycloisomerase (MLE II; EC 5.5.1.7) from Pseudomonas sp B13 have been determined from 1H NMR measurements. Both cycloisomerases convert cis,cis-muconate to (4S)-muconolacton…
Evidence for efficient non-radiative energy transfer between erbium ions in Cs 2 NaErCl 6 is provided by excitation and luminescence spectra and luminescence lifetimes. In one of the cross relaxation schemes the excitation of the 4 F 3/2 level is transferred almost exclusively to the 4 F 9/2 level in the 50-300 K temp…
Domainlike antiferromagnetic correlations are detected by SQUID measurements of the low-frequency susceptibility in the metamagnet ${\mathrm{FeCl}}_{2}$ when exposed to an axial magnetic field H at temperatures ${\mathit{T}}_{\mathit{c}}$(H)\ensuremath{\le}T\ensuremath{\le}${\mathit{T}}_{\mathit{N}}$. A distinct chang…
The topology of liquid Ge y Se 1-y (0<or=y<or=1) alloys, at the compositions y=0.33, 0.4, 0.5 and 1, is studied using neutron diffraction to measure the Bhatia-Thornton number-number partial structure factor S NN (kr 1 ), where k and r 1 are, respectively, the scattering vector and nearest-neighbour distance in real s…
We have investigated the role of surface H in Si(001) homoepitaxy using in situ medium energy ion scattering and time-of-flight H recoil detection. The addition of submonolayer coverages of atomic H produce relatively modest effects on epitaxy for ${\mathit{T}}_{\mathit{g}}$\ensuremath{\le}200 \ifmmode^\circ\else\text…
We report dielectric measurements of the orientationally disordered crystalline phase of cyclo-octanol over the frequency range 1.3 mHz--5.5 kHz. The data show that cyclo-octanol exhibits a slow relaxation that is indistinguishable in every respect from that exhibited by a supercooled liquid near its glass transition.…
The concept of exchange length is used to determine the effects of boundary scattering on transport in samples of circular and rectangular cross section. Analytical expressions are presented for an effective mean-free path for transport in the axial direction. The relationship to the phonon thermal conductivity is dis…
From a very simple description of vortices and pinning centers and without using any electrodynamical assumptions, we obtain nonlinear density profiles of vortices in type-II dirty superconductors that result from raising or lowering an external magnetic field. The results confirm a modified Bean model description of…
Rare-earth ions can easily be incorporated into fluoride glasses in moderate to large concentrations. Because these glasses possess low fundamental frequencies, they appear to have many advantages over oxide glasses as hosts for rare-earth ions used in optical amplifiers and lasers. We have investigated the optical pr…
The attenuation characteristics of a metal-clad planar optical waveguide polarizer are computed by a modified finite-difference beam propagation method, taking into consideration the complex refractive indices of the metals used and the vector characteristics of the guided mode. Numerical results for practical optical…
Despite four additional electron-withdrawing substituents, the octahalogenated porphyrins 2 are more easily oxidized than their tetra-halogenated counterparts 1. This apparent paradox can be explained by the structures of the molecules: porphyrins 2 are almost planar, whereas in 1 steric interactions are minimized by…
A hollow sphere, constructed from VO5 square pyramids and PhPO3 tetrahedra, which encapsulates a chlorine atom—this is an apt description of the anion in 1 (structure shown on the right). At first glance this anion, with its spheroidal structure, appears similar to known polyoxoanions; however, closer inspection revea…
Der Entwurf neuartiger magnetischer Materialien auf molekularer Basis , die für eine Vielzahl von Anwendungen von Interesse sind, ist immer noch eine Kunst. Um ein makroskopisches ferro‐oder ferrimagnetisches Verhalten zu erzielen, ist es erforderlich‐unter Zugrundelegung von Modellen zur Spin‐Spin‐Kopplung‐, Material…
The Rayleigh scattering coefficients of fluorine (F) and GeO2 codoped silica glasses are investigated experimentally. It is found that the Rayleigh scattering coefficients of F and GeO2 codoped silica glasses increase linearly with GeO2 dopant concentration and parabolically with F dopant concentration.
Microstructure and domain structure of sintered Nd14DyFe69.5Co5AlCr2B7.5 magnets with different grain sizes are analysed. The domain structure observed is typical for materials with high uniaxial magnetocrystalline anisotropy. Moreover, the changes in the value of coercivity μ0JHC connected with the different grain si…
Li2B4O7 is a low-Z, tissue-equivalent material and several phosphors based on this material are proposed for use in dosimetry of ionizing radiations using thermoluminescence. The synthesis of this phosphor using boric acid is a bit tricky as the stoichiometry and the crystallinity of the product depend on several fact…
A new laser crystal Lu3Sc2Ga3O12:Nd3+ with ordered garnet structure is developed. Its stimulated emission at 1.0622 μm wavelength (4F3/2 → 4I11/2 generating channel) with laser-diode and Xe-flashlamp pumping at room temperature is excited. For prospecting spectroscopic and laser investigations with Nd3+ -ion doped cry…
The electronic and transport properties of a perfect amorphous graphitic carbon model constructed by Townsend et al. [Phys. Rev. Lett. 69, 921 (1992)] are studied by first-principles calculations within the local-density approximation. It is shown that such a random system with two-dimensional interaction in a three-d…