Materials Literature
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Living free-radical bulk polymerization using a stable free radical initiator system based on nitroxide stable radicals such as TEMPO (2,2,6,6,-tetramethyl-1-piperidynyloxy) has permitted the synthesis of polymers with molecular weight distributions only slightly broader than those obtained via anionic polymerization…
To prepare medium-chain-length poly-3-hydroxyalkanoates (PHAs) with altered physical properties, we generated recombinant Escherichia coli strains that synthesized PHAs with altered monomer compositions. Experiments with different substrates (fatty acids with different chain lengths) or different E. coli hosts failed…
Abstract The formation of kaolin-group minerals in the weathering profile of granite, under the humid, temperate climate as found in Korea, was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron microprobe analysis (EMA). The granite was gradually weathered to saprolite. K-rich feldsp…
Recently, diagnostic techniques have been investigated to detect a partial discharge (PD) associated with a dielectric material defect in a high-voltage electrical apparatus. Gas insulated switchgear (GIS) is an important equipment in a substation, it is highly desirable to measure a partial discharge (PD) occurring i…
The nonlinear optical coefficients of YCa4O(BO3)3 (YCOB) have been calculated for the first time to the authors’ knowledge by use of the revised Gaussian 92 program on the basis of the anionic group theory. The d11,d12,d32, and d33 coefficients of the crystal were determined by the Maker fringes method at λ=1064 nm, a…
A great technological development for food packaging has been developed over the past few decades to satisfy consumer demands relating to more natural forms of preservation, and methods to control packaging and storage for assurance and food safety. Active packaging is, certainly, one of the most important innovations…
This paper summarises the results obtianed in the MICAT (Mapa Ibero-Americano de Corrosão Atmosférica (Latin American Map of Atmospheric Corrosion)) atmospheric corrosion project (an Iberoamerican project on atmospheric corrosion, involving 14 countries and 75 atmospheric test sites) for zinc specimens exposed for 1–4…
Annealing studies were carried out to investigate the morphological changes in segmented polyurethane elastomers (PUR) induced by annealing as a function of temperature. Four series of PUR elastomers were studied by varying the hard segment type (MDI/BD and H 12 MDI/BD), the content of the hard segment (35-57% by weig…
Praseodymium‐doped glasses were prepared in the Ga‐Na‐S (GNS) system and their optical properties were studied. A single‐mode fiber with an attenuation loss of 1.2 dB/m at a wavelength of 1.31 μm was fabricated using an extrusion method, and the amplification characteristics were measured in the bidirectional pumping…
Two different lengths of P-O bonds in the PO 4 units of phosphate glasses are found by neutron diffraction experiments of high resolution in real space. The two lengths are related to bonds of the phosphorus atom with the terminal and the bridging oxygen atoms. The mean lengths and widths of both P-0 distance peaks ch…
We report the results of a study, using digital video microscopy, of the melting transition in a quasi-two-dimensional suspension of uncharged silica spheres. This system was chosen to further test the dependence of the two-dimensional melting transition on the functional form of the colloid-colloid interaction. Our e…
Abstract Gold nanoparticles can be deposited on several metal oxides by liquid phase grafting (LG) of dimethyl gold acetylacetonate. They exhibit high catalytic activities for the oxidation of CO and of H2 at low temperatures, below and above 273 K, respectively.
Pulsed magnetic fields up to 50 T and neutron-diffraction measurements have been used in a systematic investigation of the lattice and magnetic factors contributing to the charge-melting transition in ${L}_{1/2}{\mathrm{Ca}}_{1/2}{\mathrm{MnO}}_{3}$ perovskites $(L:\stackrel{\ensuremath{\rightarrow}}{Y}\mathrm{La}).$…
As part of a program to develop high temperature/high performance structural resins for applications on a Mach 2.4 high speed civil transport, a phenylethynyl terminated imide oligomer designated PETI-5 has been under investigation. The oligomer was prepared at a calculated number average molecular weight of about 500…
The structure of canavalin was refined to 2.1 and 2.0 A resolution in cubic and hexagonal crystals of space group P2(1)3 and P6(3), respectively. The threefold molecular symmetry is expressed in the symmetry of both crystals, where each identical subunit is an asymmetric unit. The canavalin subunit consists of two ver…
The effects of fluorinated acrylate monomers on the electro-optical and morphological properties of polymer dispersed liquid crystal (PDLC) films are reported. The partial fluorination of host polymer matrices resulted in improved optical properties and better defined morphologies. An enhancement in contrast ratio was…
The trap-related photoluminescence dynamics in CdSxSe1−x nanocrystals (for x=0.24 and x=0.74) in glass were studied in the temperature interval 10–300 K. A close link between the temperature behavior of the photoluminescence decay rate and that of the photoluminescence efficiency was found, which indicates a dominant…
The chemical diffusivity of 1.8 mol% aluminum‐doped BaTiO 3−δ was measured on single‐crystal specimens, as a function of ambient oxygen partial pressure, in the range 10 −18 atm ≤ P O2 ≤ 1 atm and at temperatures of 800°≤ T ≤ 1100°C, via a conductivity‐relaxation technique. As in the polycrystalline, undoped BaTiO 3−δ…
The inhibitive action of triazoles on the corrosion of mild steel has been studied through weight loss and various electrochemical techniques. Results obtained show that these organic compounds are very good inhibitors. Triazoles are able to reduce the corrosion of steel more effectively in 1M HCl than in 0·5M H2 SO4…
Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.