Materials Literature
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A biomimetic templating approach to the synthesis of lamellar silicas is demonstrated. The procedure is based on the hydrolysis and cross-linking of a neutral silicon alkoxide precursor in the interlayered regions of multilamellar vesicles formed from a neutral diamine bola-amphiphile. Unlike earlier surfactant-templa…
Abstract Vision and other light‐triggered biochemical transformations in plants and living organisms represent a sophisticated biological processes in which optical signals are recorded and transduced as (physico)chemical events. Photoswitchable biomaterials are a new class of substances in which optical signals gener…
Composite structures in which amorphous and crystalline phases coexist are formed by some organisms. The spicules of the sponge Clathrina are shown to be composed of a crystalline calcitic core and an outer layer of amorphous CaCO 3 (see figure). The latter material, normally a highly unstable mineral, is stabilized i…
Shear-induced crystallization of isotactic polypropylene (iPP) homo-, block, and random copolymers was studied and compared to that in quiescent melt. It was evidenced by means of the thermo-optical technique that melt-shearing, caused by fiber pulling, is associated with the development of α-row-nuclei. The surface o…
Corrosion of steels causes a loss of about 121 billion dollars annually and half the iron produced at present is used for the replacement of the existing deteriorated structures. Corrosion, being an electrochemical phenomenon, can be tackled through the use of electrochemistry and conducting polymers. Stainless steels…
Abstract The equilibrium H- and O-isotope fractionations can be approximated by the following equations which are based on experimental, empirical and/or theoretical data: Hydrogen: 1000 ln α kaolinite-water = −2.2 × 10 6 × T −2 − 7.7 Oxygen: 1000 ln α kaolinite-water = 2.76 × 10 6 × T −2 − 6.75 1000 ln α smectite-wat…
An existence result for the Cahn–Hilliard equation with a concentration dependent diffusional mobility is presented. In particular, the mobility is allowed to vanish when the scaled concentration takes the values $ \pm 1$, and it is shown that the solution is bounded by 1 in magnitude. Finally, applications of our met…
Electrochemical polymerization of aniline, on a Pt foil electrode coated with poly(methyl methacrylate) (PMMA), produces a homogeneous, free-standing, flexible, and conductive polymer film. The conductivity of the films depends on the aniline content and reaches 0.1–0.2 S/cm for films having aniline content of 15% or…
Rubber particle size is an important issue in toughening of engineering thermoplastics. Use of core-shell impact modifiers offers the advantage of a predetermined particle size; however, these particles must be appropriately dispersed in the matrix polymer to be effective for toughening. Recent work has shown that cor…
To improve the performance of rubber compounds using precipitated silica as a reinforcing filler, the silica surface was directly modified by (1) adsorption of a surfactant onto the surface, (2) adsolubilization of an organic monomer, (3) in situ polymerization of the monomer in the surfactant bilayer, and (4) partial…
Blends of chitosan with strongly crystalline polyamides (nylon-4 and nylon-6) and weakly crystalline polyamides (caprolactam/laurolactam and Zytel®) were investigated. Phase behavior, morphology, interactions with water, mechanical properties, and catalytic reactivity were studied. Films were made from formic acid sol…
The effect of hydrogen on the stacking-fault energy has been evaluated in a 310 austenitic stainless steel. The stacking-fault energy was calculated from measurements of the radius of curvature of dislocation nodes, which were imaged using weak-beam conditions. Preliminary results indicate that the presence of 40 torr…
We have investigated the effect of hydrostatic pressure on interdiffusion in multilayers composed of alternating layers of amorphous Si (2.7 nm) and Ge (3.1 nm). Samples were annealed at 420 °C at pressures between 0 and 2.8 GPa in an externally heated diamond anvil cell. Interdiffusion was measured by monitoring the…
The symmetry classification of three-dimensional periodic or aperiodic crystals is given a coordinate independent formulation which establishes the precise connection between Fourier-space and superspace crystallography. Superspace groups emerge without having to embed an aperiodic crystal in a higher-dimensional spac…
The crystallographic and magnetic structures of at 77 K have been refined by Rietveld analysis of the high-resolution neutron powder diffraction data. The analysis indicates that has -type structure ( ). The Cr atoms occupy 12j, 6g and 4f sites with occupancies 0.12, 0.10 and 0.50 respectively, but Cr atoms are absent…
High-quality homoepitaxial diamond films having large terrace width have been successfully grown on (001) diamond substrates. Schottky contact properties as well as the surface morphology and the film crystallinity of the deposited films were characterized in order to examine a potential for electronic applications. I…
The role of ion energy over the range 5 eV≤E≤20 keV in the production of the dense diamondlike sp3-bonded phase of carbon films deposited from ion beams has been investigated. Films with a significant sp3 component (≳40%), as determined by electron energy loss spectroscopy (EELS), can be formed over the wide energy re…
We report on studies using the x-ray surface forces apparatus (XSFA) to compare the structure of a liquid crystal confined between hard surfaces and, for the first time, between soft surfaces that can deform due to the stresses imposed by the confined fluid. We find that the alignment of smectic domains in confined fi…
Core and valence band photoemission data of hydrogen passivated Si(111):H surfaces yield surface Fermi level positions that are indicative of a near-surface depletion layer for n- as well as p-type samples. The bulk Fermi level positions are attained after annealing at ∼400 °C. These observations are explained in term…
Stable blue photoluminescence (PL) at 580 nm visible to the naked eye has been observed for the samples consisting of Ge nanocrystals (nc-Ge) embedded in a silicon oxide (SiO2) solid matrix, fabricated by atmospheric pressure chemical vapor deposition techniques. Raman spectroscopy measurement strongly suggests the ex…