Materials Literature
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Liquid crystals with one or more trans-1,3-dioxane building blocks (see Figure) combine high dielectric anisotropy with low birefringence and favorable mesogenic and viscoelastic properties. A new, building-block-oriented synthetic strategy is described that offers convenient access to trans-1,3-dioxane–based core str…
The pretilted planar-to-homeotropic reorientation transition of nematic liquid crystals with positive dielectric anisotropy is achieved with a record fast risetime, as fast as 40 ns, by employing a customized electro-optic cell with small area and cell gap and with metal-coated electrodes and by applying electric fiel…
ZnO:In films were prepared by a sputtering method with targets facing. The lowest resistivity film is obtained at a substrate temperature of 150 °C using a ZnO target doped with 3 wt % In2O3. At substrate temperatures above 300 °C the resistivity of the film increases as the carrier concentration decreases. This impli…
Secondary ion mass spectrometry (SIMS) was used to determine the nature of the adhesive bonding which occurs through interchain transesterification (ITR) in thermosetting polyester materials (TS) and in liquid crystalline polyester polymers (LCP). An all aromatic copolyester thermoset was prepared as a deuterated and…
The ESRF undulator beamline ID14 'Quadriga' is dedicated to monochromatic macromolecular crystallography. Using two undulators with 23 mm and 42 mm periods and a minimum gap of 16 mm installed on a high-beta section, it will provide high-brilliance X-ray beams at around 13.5 keV, as well as a wide tuneability between…
Proposes an algorithm for the computation of maximum needle penetration force; it introduces the direct dependence of penetration force on fabric structural parameters and warp and weft geometrical and mechanical properties. Uses the approach to the simulation of local deformation of woven material which accounts for…
Si 3 N 4 /SiC composite materials have been fabricated by reaction‐sintering and postsintering steps. The green body containing Si metal and SiC particles was reaction‐sintered at 1370°C in a flowing N 2 /H 2 gas mixture. The initial reaction product was dominated by alpha‐Si 3 N 4 . However, as the reaction processed…
The electrochemical deposition of polypyrrole (PPy) potentiodynamically and potentiostatically over monolayers of 1-(2-thioethyl)pyrrole (1-TEP) is described. The relationship between monolayer oxidation and PPy growth depended strongly on the electrolyte. In propylene carbonate/LiClO 4, the PPy polymerization potenti…
S2 p and O1 s photoelectron spectra were obtained for the 95(0.6Li 2 S0.4SiS 2 )5Li 4 SiO 4 oxysulfide glass prepared by twin‐roller quenching. A four‐peak deconvolution technique was used to separate the S2 p peak of the glass into the components of bridging and nonbridging sulfur atoms. As a result of the deconvolut…
Electronic and structural properties of polypyrroles oxidized by different concentrations of chlorine atoms or molecules are studied with the use of a density functional method implemented with plane waves and pseudo-potentials for the core electrons. The calculated properties are compared with those obtained for the…
Shape memory alloy (SMA) wires can be embedded in a host material to alter the stiffness or modal response and provide vibration control. The interaction between the embedded SMA and the host material is critical to applications requiring transfer of loads or strain from the wire to the host. Although there has been a…
The motion of charge carriers in many solid ionic conductors is determined both by long-range Coulomb interactions and by structural disorder in the host matrix. While the dynamical behaviour at low frequencies is governed by long-range, thermally activated hopping processes, localized motions of the charge carriers w…
During the synthesis of ZnS powders by wet chemical precipitation, the formation of nanoporous spheres is observed. The powders have been investigated using thermogravimetric analysis, X-ray diffraction and optical spectroscopies. Nanopore formation can be explained by several stages of growth. The formation of nanopa…
A ridge and fringe field multi-domain homeotropic (RFFMH) liquid crystal display was demonstrated. The operating principle of this new display mode is the combination effect of a fringe field and ridge structure to control the tilt direction of the liquid crystal molecules when a voltage is applied. No rubbing treatme…
The nucleation and growth of wollastonite crystals have been investigated in stoichiometric CaO⋅SiO2 glass. In the temperature range of 1043 to 1073 K, the nucleation rate was evaluated from crystallite densities, determined by optical microscopy on samples subjected to double-stage heat treatment. Turnbull’s method w…
A negative temperature coefficient of electrical resistivity (TCR) has been observed in Ti 50- X Ni 50+ X (at.%; X =1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5) in the temperature range between 20 and 350 K. The resistivity vs temperature curve has no hysteresis and the relative resistivity at 20 K (ρ 20 K /ρ 350 K ) decreases…
Thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry (DSC) have been used to study the effect of physical ageing in polyetherimide (PEI: ULTEM 1000™). Ageing temperatures (Ta) between 48 and 8°C below the glass transition temperature (Tg) measured by DSC at 10°Cmin-1 heating rate (…
The synthesis and mesomorphic properties of several homologues of (S)-(+)-1-methylheptyl 4-[4(trans-4-n-alkoxycinnamoyloxy)benzoyloxy]benzoates (series I) and (S)-(+)-1-methylheptyl 4-[4-(trans-4-n-alkoxy-alpha-methylcinnamoyloxy)benzoyloxy]benzoates (series II) are described. The influence of the alpha -methyl group…
This paper describes studies of some photophysical properties of non-covalent planar aggregates of hematoporphyrin and protoporphyrin. This porphyrin species has been recently discovered and can be generated in lipid bilayers such as liposomes and inner mitochondrial membranes. The relative weight of this species in d…
In this study, we sputter deposited titania films of thickness ranging from 256 to 705 nm on unheated substrates and studied changes in phase constituency as a function of film thickness. X-ray diffraction, and infrared spectroscopy were used for post-deposition analysis. The results show that the thinnest films consi…