Materials Literature
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We have been developing an instrument that combines the techniques of x-ray photoelectron spectroscopy and zone plate microfocusing to perform spectromicroscopy. The X1A undulator provides a bright photon source in the soft x-ray range with a high degree of spatial coherence (a requirement for zone plate focusing). A…
Novel composite electrode structures have been fabricated by single‐step electropolymerization of polypyrrole onto a porous graphite fiber matrix. The graphite substrate provides a lightweight structure with high surface area. The available charge capacity of the composite electrodes was proportional to the electropol…
ABSTRACT The role of environmental factors in seasonal succession of six clones of marine diatoms was examined by testing effects of various combinations of temperature (5°, 10°, 15°, 20°C) and photoperiod (10, 12, 14, 16 h) on time to germination of resting stages and subsequent vegetative cell division rates. Restin…
Abstract Potassium beryllium borate fluoride, KBe 2 · BO 3 F 2 , is rhombohedral (hexagonal axes) R 32 (No.155), a = b = 4.427(4) Å, c = 18.744(9) Å, V = 318.3(4) Å 3 , M = 153.93, D m = 2.40g · cm −3 , D x = 2.41 g · cm −3 for Z = 3, F (000) = 222, μ = 11.84 cm −1 , T = 296 K. The crystal structure has been determine…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical Oxidation of Polyaniline in Nonaqueous Electrolytes: "In Situ" Raman Spectroscopic StudiesM. Lapkowski, K. Berrada, S. Quillard, G. Louarn, S. Lefrant, and A. PronCite this: Macromolecules 1995, 28, 4, 1233–1238Publication Date (Print):February 1, 1995Publica…
The cooperative diffusion coefficient ${\mathit{D}}_{\mathit{c}}$ for spherical particle suspensions is calculated using a ``mode-coupling'' method which extends previous calculations of ${\mathit{D}}_{\mathit{c}}$ for critical fluids and semidilute polymer solutions. The renormalization of the viscosity in the veloci…
Intersystem crossing is the crucial first step determining the quantum efficiency of very many photochemical and photophysical processes. Spin-crossover compounds of first-row transition metal ions, in particular of Fe(II), provide model systems for studying it in detail. Because in these compounds there are no compet…
The thermal conductivity and diffusivity of free-standing silicon nitride (Si-N) films of 0.6 and 1.4 μm in thickness are measured. A new experimental technique, the amplitude method, is proposed and applied to measurement of the thin-film thermal diffusivity. The thermal diffusivity is determined by three independent…
Poly(A) polymerase synthesizes poly(A) tails rapidly and processively only when the substrate RNA is bound simultaneously by two stimulatory proteins, the cleavage and polyadenylation specificity factor (CPSF) and poly(A)-binding protein II (PAB II). A burst of synthesis terminates after the addition of about 250 nucl…
Experimentally derived optical constants and X-ray attenuation cross sections were used to construct the complete dipole oscillator strength distribution for solid, dry DNA. Monte Carlo simulations of the energy loss by electrons of initial energy 5 keV to 1 MeV in DNA were performed using cumulative inelastic cross s…
In this paper we discuss the optical reflective properties of single and multidomain cholesteric liquid crystals both experimentally and theoretically. The multidomain system has been prepared by dispersing a low concentration of polymer in a cholesteric liquid crystal. This results in a (passive) bistable colorful re…
We present the results of computer simulation studies of SrTiO 3 . After deriving a reliable potential model, we concentrate on the properties of defects and dopants. Our calculations are used to propose a defect model that is consistent with experimental observations. For vacancy disorder, the calculations show that…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdsorption of DNA to Mica, Silylated Mica, and Minerals: Characterization by Atomic Force MicroscopyMagdalena Bezanilla, Srinivas Manne, Daniel E. Laney, Yuri L. Lyubchenko, and Helen G. HansmaCite this: Langmuir 1995, 11, 2, 655–659Publication Date (Print):February 1, 1995P…
A suspended particle with specific director anchoring on its surface introduces a complex distortion field in a nematic liquid crystal matrix. Topological defects---disclination loops, boojums, and hedgehogs, are needed to match the director near the particle surface with that at the far distance, which is determined…
Techniques for the design of continuously tapered two-dimensional (2D) subwavelength surface-relief grating structures for broadband antireflection surfaces are investigated. It has been determined that the Klopfenstein taper [ Proc. IRE44, 31 ( 1956)] produces the optimum graded-index profile with the smallest depth…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNegative Thermal Expansion and Phase Transitions in the ZrV2-xPxO7 SeriesV. Korthuis, N. Khosrovani, A. W. Sleight, N. Roberts, R. Dupree, and W. W. Jr. WarrenCite this: Chem. Mater. 1995, 7, 2, 412–417Publication Date (Print):February 1, 1995Publication History Published on…
Silicon oxycarbide glasses have been synthesized by inert atmosphere pyrolysis at 1000°C of gel precursors obtained by cohydrolysis of triethoxysilane, HSi(OEt) 3 , and methyl‐diethoxysilane, HMeSi(OEt) 2 . The oxycarbide structures have been carefully characterized by means of different techniques such as 29 Si magic…
Abstract Modified atmosphere packaging is becoming increasingly common. It has been claimed that the technique enables significant shelf‐life extension but in so doing presents an increased public health risk. This paper reviews the literature relating to the scientific basis of these claims. It demonstrates that shel…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparing Catalytic Materials by the Sol-Gel MethodDavid A. Ward and Edmond I. KoCite this: Ind. Eng. Chem. Res. 1995, 34, 2, 421–433Publication Date (Print):February 1, 1995Publication History Published online1 May 2002Published inissue 1 February 1995https://pubs.acs.org/d…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTWater Content and Particle Texture of Synthetic Hydrotalcite-like Layered Double HydroxidesSang Kyeong Yun and Thomas J. PinnavaiaCite this: Chem. Mater. 1995, 7, 2, 348–354Publication Date (Print):February 1, 1995Publication History Published online1 May 2002Published iniss…