Materials Literature
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Infinitely degenerate states at an energy E=0 on a two-dimensional Penrose lattice are investigated in a tight-binding model where atomic orbitals are located at vertices of rhombuses. The states with E=0 are all strictly localized and have amplitudes only on some specific vertices, which are three-edge vertices and s…
The large third-order nonlinear optical properties ${\ensuremath{\gamma}}_{\mathrm{ijkl}}(\ensuremath{-}{\ensuremath{\omega}}_{4};{\ensuremath{\omega}}_{1},{\ensuremath{\omega}}_{2},{\ensuremath{\omega}}_{3})$ observed for conjugated organic linear chains, such as polyenes, are explained by strong electron-correlation…
We have derived a nonlocal theory of thermal conductivity for the case in which the heat is carried by phonons. There is a nonlocal relation between the heat current J(r) and the temperature gradient \ensuremath{\nabla}T(r'). The nonlocal theory is needed whenever the phonon mean free path is long compared to the dist…
Hybrid elements containing optical power with both diffractive (holographic) and refractive components are shown to be useful for obtaining arbitrary or, in special cases, achromatic dispersive characteristics. In one configuration a volume holographic element is coated on the surface of a crown glass lens, and by var…
A new approach for including full-potential terms in a linear-muffin-tin-orbital calculation is presented. The implementation for crystals leads to a method which is at the same time fast and accurate. Calculated elastic constants and phonon frequencies for Si agree well with experiment.
The infrared-absorption spectrum of a-${\mathrm{SiO}}_{2}$ is analyzed in terms of its transverse-optic (TO) and longitudinal-optic (LO) vibrational modes. It is shown that the independent-oscillator model for the a-${\mathrm{SiO}}_{2}$ dielectric function fails to yield a consistent value of mode strength for the opt…
Barium titanate semiconducting ceramics with positive temperature coefficients of resistance (PTCR) which were donor doped with holmium have been studied with respect to the effect of holmium concentration on the conductivity in the range of 0.05 to 0.8 at.%. The transition from conductive to insulating behaviour at r…
The electrodeposition of poly(pyrrole) in the presence of a polyanionic electrolyte (poly(styrenesulphonate), poly(vinylsulphate) or Nafion) leads to the formation of a film of a composite polymer at the surface of the two polymeric structures prevents the anionic dopants from being expelled during the dedoping, conse…
The magnetic properties of AISI 4130 steel after eight heat treatments have been investigated. Properties such as hysteresis loss, coercivity, and initial permeability were found to be closely interrelated. Furthermore, they were each dependent on the hardness of the material. A relationship between the hardness and p…
The magnetic properties of a number of specimens of AISI 1000 series plain carbon steels have been measured as functions of chemical composition, microstructure and heat treatment. The results showed that for a given morphology of the carbides the magnetic properties such as coercivity and permeability varied smoothly…
A microscopic theory for obtaining the polarized Raman spectrum of Fibonacci chains is developed and applied to GaAs-AlAs heterostructures. The results of the theory, without adjustable parameters, are compared with experimental data, and remarkable agreement is attained. The treatment is performed in real space and,…
After recoil implantation of Coulomb-excited $^{57}\mathrm{Fe}$ into $\ensuremath{\alpha}\ensuremath{-}\mathrm{Z}\mathrm{r}$ at 24 K, 30% of the implanted atoms end up on interstitial positions where they experience large electric field gradients. Between 40 and 100 K the quadrupole splitting shrinks by a factor of 2…
We report neutron-scattering experiments on single crystals of the layered perovskite ${\mathrm{La}}_{2}\mathrm{Ni}{\mathrm{O}}_{4+\ensuremath{\delta}}$. Three-dimensional magnetic order sets in at ${T}_{N}=70$ K for $\ensuremath{\delta}\ensuremath{\cong}0.05$. Strong two-dimensional magnetic correlations exist for $T…
The photochromism of N‐phenyl‐rhodaminelactame (3′ ,6′ ‐bis‐(diethylamino)‐2‐phenyl‐spiro[1H‐isoindole‐1,9′[9H] Xanthaen]‐3‐[2H]‐one) was investigated in solutions of acetonitrile, dioxane and mixtures of dioxane with H 2 0, methanol and ethanol by laser flash time resolved absorption measurements. The colouring react…
Abstract The paper describes the arrangement of the atoms within rhombohedral crystals of 2Zn pig insulin as seen in electron density maps calculated from X-ray data extending to 1.5 Å (1 Å = 10-10 m = 10-1 nm) at room temperature and refined to R = 0.153. The unit cell contains 2 zinc ions, 6 insulin molecules and ab…
Batch foam separation has been employed to separate Saccharomyces carlsbergensis cells from their broth without the use of any external surface-active agent. A model has been developed to predict the foamate cell concentration as well as the variation of cell concentration in the bulk liquid in the foam column as a fu…
Abstract The effect of dibenzylidene sorbitol (DBS) as a nucleating agent on the crystallization of poly(ethylene terephthalate) (PET) has been studied. It has been found that DBS, when incorporated into the polyester, at a 0.5–1.0 wt % level, significantly lowers the induction period and reduces the half‐time of crys…
Abstract The thermal and crystallization behavior of blends of glass fiber reinforced polyphenylene sulfide (PPS) with polyethylene terephthalate (PET) has been reported. The blends showed two overlapping melting peaks and two separate crystallization peaks. The heat of crystallization of PPS was found to decrease con…
Sandvik introduces ‘second generation’ Duplex stainless steel hollow bar. Sandvik Steel UK has announced the introduction of SAF 2205 stainless steel hollow bar for use in the manufacture of machined components. This new grade represents. Sandvik's ‘second generation’ of Duplex stainless steel — combining the properti…
Abstract Four soils (Umbric Dystrochrepts) formed in loess in eastern Southland, at altitudes of 195‐365 m and under a rainfall of 1000 mm to over 1400 mm, were mineralogically and chemically analysed to determine the soil variation in this area, and to establish whether mineralogical or chemical criteria could be use…