Materials Literature
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Polymer-dispersed liquid crystals (PDLCs) are electrooptic materials that modulate light through electrical control of the refractive index similar to other liquid devices. Like dynamic scattering and smectic displays, PDLCs switch between scattering and clear states. PDLC-type devices consist of droplets of low-molec…
This chapter provides an overview of current researches on liquid crystalline polymers (LCP's). Topics include syntheses of main-chain and side-chain LCP's, structured characterization of LCP's and LCP networks and rheology and processing. Applications of LCP/polymer blends as self-reinforced polymers and electro-opti…
The protein Felix was designed de novo to fold into an antiparallel four-helix bundle of specific topology. Its sequence of 79 amino acid residues is not homologous to any known protein sequence, but is "native-like" in that it is nonrepetitive and contains 19 of the 20 naturally occurring amino acids. Felix has been…
A quantum Ising spin chain with nearest-neighbour couplings arranged in a quasiperiodic sequence is considered. The Cantor set structure of the energy spectrum is analysed in terms of the thermodynamic description of multifractals. Evidence is given that the spectrum of scales develops a singular behaviour: this is as…
The authors propose to use multifractal analysis in reciprocal space as a tool to characterise, in a statistical and global sense, the nature of the Fourier transform of geometrical models for atomic structures. This approach is especially adequate for shedding some new light on a class of structures introduced recent…
It is argued that the threshold transition that occurs in the phase-deformation model of charge-density-wave systems in an applied electric field is destroyed in all dimensions by phase slips (amplitude fluctuations). The one-dimensional case is demonstrated using an exactly soluble model.
The structure of succinonitrile in its orientationally disordered phase was reexamined through extended X-ray diffraction measurements. It was solved by using both the analytic procedures of symmetry-adapted functions and a Frenkel model assuming discrete orientations. A possible translation-rotation coupling was incl…
Inelastic neutron scattering was used to investigate liquidlike motions and the nature of a dynamic transition in myoglobin, a small globular protein. The signature of the transition is a strong enhancement of low-frequency density fluctuations and a corresponding decrease in elastic scattering above 180 K. It is show…
The distribution functions and RMS value of the Barkhausen noise are studied in samples of (110)[001] Fe-Si3% as function of the magnetization and applied field for several angles between the applied field and the [001] crystallographic axis. The results obtained are explained in terms of C domain nucleation, growth,…
The anelastic relaxations observed between 100 and 600 K for a very high purity magnesium are presented. The performed experiences show an internal friction peak P1 placed around 410 K whose activation parameters are determined (v = 1000b3, HP1 = 1 eV). The P1 behaviour is similar to that of the P1 peak observed in 99…
The crystal structure of the natural thromsonite, Na 1•00 Ca 1•88 Sr 0•12 Al 5 Si 5 O 20 •6H 2 O, at 13 K has been refined from neutron diffraction data. The structure is generally very close to the room-temperature structure and shows no sign of cation ordering. Among the significant differences are decreased T-O-T a…
Young's modulus was measured as a function of electrical bias on o-${\mathrm{TaS}}_{3}$ between 60 K and the Peierls transition temperature, ${\mathit{T}}_{\mathit{c}}$=220 K. ${\mathit{Y}}_{\mathrm{CDW}}$, the modulus difference between stationary and rapidly sliding charge-density-wave states, increases as the squar…
The validity of Rayleigh's hypothesis with permeable media is investigated. For the two-dimensional transmission problem, the extinction theorem and boundary integral equations are obtained within a common framework, for the surface with periodic corrugations. The surface field functions are found from the integral eq…
X-ray diffraction and magnetization have been measured for Fe 1- x Al x alloys produced by facing target type DC sputtering. The bcc phase is obtained for x =0-0.65, the amorphous phase for x =0.7-0.9 and the fcc phase for x =0.9-1.0 on water-cooled (WC) substrates, while the bcc phase is obtained for x =0-0.55, the a…
A new formulation of the weighted density approximation, the so-called modified weighted density approximation (MWDA), has been developed recently by Denton and Ashcroft [Phys. Rev. A39, 4701 (1989)]. In the present article, the MWDA theory is examined by applying it to the freezing of simple liquids in low dimensions…
A semiempirical many-body potential [J. Tersoff, Phys. Rev. Lett. 61, 2879 (1988)] has been used to model carbon clusters (${\mathit{C}}_{\mathit{n}}$) in the size range 50\ensuremath{\le}n\ensuremath{\le}72. Ground-state geometries are identified by simulated annealing. Our results show that, for these sizes, all the…
An angle-resolved high-resolution electron-energy-loss-spectroscopy study is reported of the surface-plasmon spectrum on Ag(001) along different azimuths. A single loss energy is observed which disperses linearly with exchanged momentum ${\mathit{q}}_{\mathrm{?}}$ from 3.69\ifmmode\pm\else\textpm\fi{}0.01 eV with a sl…
A Fibonacci optical superlattice is analyzed which is made from a single crystal with quasiperiodic laminar ferroelectric domain structures. The second-harmonic generation in this system is studied. Because of the dispersive effect of the refractive index, the second-harmonic spectrum does not reflect the symmetry of…
The adsorption and desorption kinetics for SiCl4 on Si(111)7×7 were studied using laser-induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. TPD experiments monitored SiCl2 as the desorption product at approximately 950 K using a heating rate of β=9 K/s. SiCl2 was also observed as…
Cristallisation dans Cmca avec a=13,215, b=5,943, c=5,938 A, z=4; affinement jusqu'a R=0,017. La structure est constituee de couches infinies d'antisprismes carres de LaO 4 S 4 , qui sont connecte entre eux par leurs aretes. Ces couches, paralleles a (100), ont en commun un oxygene ou un plan de disulfure. Les liaison…