Materials Literature
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We report a theoretical study of various structures of chiral nematic liquid crystals, confined to submicrometer cylindrical cavities with tangential anchoring conditions. The Frank-Oseen free energy with additional surface energy terms is used to find nematic director fields, free energies, and stability diagrams of…
Abstract A series of smectic C * liquid‐crystalline (LC) block copolymers were successfully synthesized via the living anionic polymerization of polystyrene with optically active methacrylate monomers containing ( S )‐2‐methylbutyl 4‐(4‐hydroxyphenylcarbonyloxy)‐biphenyl‐4′‐carboxylate mesogens. These materials are th…
The effect of non-tetrahedral cations on the silicon–oxygen vibrational modes in complex silicates was modelled in a small-cluster approximation by introducing a shell containing first- and second-order neighbours of the peripheral oxygen atoms of the Si—O cluster. As an example, the proposed method was applied to stu…
To unravel the effects of the volume-excluding central core and the mesogenic pendant group on both the glass-forming ability and morphological stability of the thermally quenched glass, nine model compounds were synthesized that contain various nematogenic and cholesteryl pendant groups. The glass-forming ability of…
Abstract It is known that chromium influences the growth of an alumina oxide layer on β‐NiAl at high temperatures. It has been claimed that oxidized chromium will act as nuclei for the θ → α‐alumina phase transformation. This study presents RBS‐data on the presence of chromium in the oxide scale which tends to substan…
Abstract An azobenzene-functionalized meterial was used to perform comparative investigation of molecular arrangements in self-assembled monolayer film and in crystalline state. By the means of atomic force microscopy and absorption spectroscopy, a unique herringbone structure was revealed in the densely packed self-a…
In this paper we present findings from molecular dynamics simulations that investigated the changes induced in molecularly thin n-octane films, as a result of increasing solid-methylene unit energetic affinity. The solid surfaces were deprived of any topographical features and were modeled as atomically smooth 10-4 Le…
Abstract Polyethylene blends (LLDPE:HDPE ≈ 2:1 by wt) used in NASA's balloon film applications can be effectively reinforced by addition of a small amount of liquid crystalline polymer (LCP). Cast and blown PE films containing ≈ 10% LCP show an appreciable enhancement in tensile modulus ≈400% over that of the neat PE…
Ceramics of the two compositions of KTa1−xNbxO3 (KTN) with x = 0.3 and 0.4 have been densified thanks to the addition of LiF. Densities been determined as a function of sintering temperature, time and amount of LiF. Dielectric investigations have shown that the composition corresponding to x = 0.4 is more densified th…
X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and electrochemical potentiodynamic experiments have been used to study the pretreatment of 2024–T3 aluminium alloy before conversion coating. The pretreatment process included vapour degreasing, alkaline cleaning and Cr based acidic deoxidising ste…
The three-dimensional structure of the Saccharomyces cerevisie fatty acid synthase was computed from electron microscopy of stain images. The barrel-shaped structure (point group symmetry 32) has major and minor axes of approximately 245 x 220 A, respectively, and consists of two different subunits organized in an alp…
Designs are given for gallium-arsenide subwavelength grating retarders operating at 10.6 μm. A design procedure is detailed that takes into account the reflections at all surfaces and that uses numerical optimization to improve the transmittance of the retarders to nearly 100%. It is shown that the homogeneous uniaxia…
A second virial theory is presented to study the influence of a slight flexibility on the nematic-smectic A transition in fluids of freely rotating hard rods. The spinodal is located by performing a bifurcation analysis of the equation describing the single-particle distribution function. A closed expression for the s…
A photolithographic process has been used to form cross-shaped patterns in 3-μm-thick nickel foils. Patterns with cross arm dimensions in the 10-20-μm range, and with periodicities in the 16-26-μm range, yield self-resonant bandpass filters for wavelengths in the 20-25-μm region. Transmittances as high as 80% were ach…
Abstract The radical polymerization of acrylic acid and sodium 4‐styrenesulfonate in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan‐poly(acrylic acid) and chitosan‐poly(4‐styrenesulfonate). Kinetic results do not permit to propose any mechanism in…
Abstract A backscattered electron energy spectrometer, based on a toroidal energy analyser and an annular detector, has been devised and adapted for use in a scanning electron microscope. Computer simulations have been carried out for equipotentials and trajectories of electrons in the toroidal deflector, which permit…
We have studied the scaling behavior of the bulk structure in a symmetric diblock copolymer system using small-angle scattering. We have identified a crossover between the inter mediate-segregation regime and the strong-segregation limit at χ N ≃ 29. In the inter mediate-segregation regime (χ N ≃ 5 − 29), the characte…
Abstract Ferroelectricity and thus piezoelectricity are well known features of low molar mass chiral smectic C (S c * ) liquid crystals. We present a new technique to orientate macroscopically the director as well as the smectic layers of a S c * ‐polymer network by applying a suitable mechanical field. The uniform or…
Interposition of a fine-scale X-ray absorbing mesh between a Laue-diffracting crystal specimen and the photographic plate recording its topographic image splits the diffracted beam into an array of individually identifiable microbeam elements. Direction differences between the microbeams in the array, which are twice…
Using light scattering, the thickness dependence of the isotropic-nematic phase transition temperature ${\mathit{T}}_{\mathit{NI}}$ in a thin film of octylcyanobiphenyl (8CB) is studied in two distinct geometries: with and without strain. We observed a large stress induced shift in ${\mathit{T}}_{\mathit{NI}}$, as a f…