Materials Literature
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Alkali-retting was applied to kenaf bast ribbons and the mechanical properties and the structure of the retted fibers were investigated. In order to produce the fibers with preferable surface smoothness, the retting should be made at the NaOH concentration higher than 4 %. The tensile properties, however, showed a max…
Field emission from nanostructured carbon materials is analyzed by applying the model of emission center in which the emitting surface contains two phases of carbon having substantially different electronic properties. In accordance with this model, the proposed mechanism involves electron tunneling through two potent…
Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol-water molar ratio, gamma, in the precursor solution was va…
Abstract A ternary hybrid of bismaleimide‐polyetherimide‐silica (BMI‐PEI‐SiO 2 ) was synthesized by sol‐gel reaction and characterized by scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDX), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that…
This work studies the influence of the climatic conditions during the Canadian winter using high-density PE (HDPE) samples exposed to weather conditions during different periods of time. Under these conditions, it is reasonable to think that the chemical changes caused by the climatic degradation will at first sight b…
The taxonomic and environmental characteristics of the diatom flora found in three bodies of water in the wetlands of Jilotepec-Ixtlahuaca, Estado de Mexico are described. Six samplings were made (January-October, 2001). Benthic and planktonic diatoms growth were collected.The samples were analyzed with a Light Micros…
Spectroscopic data on crystals of rare-earth compounds having structural instability due to the cooperative Jahn–Teller effect are reviewed. Based on an analysis of these data, it is inferred that the dynamic coupling of low-frequency electronic excitations of the rare-earth ions with crystal lattice vibrations plays…
The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition reg…
The microstructures of four kinds of Zircaloy-2-type materials with neutron exposure up to about 15 × 1025 n/m2 (E>1MeV) were examined to investigate the microstructural evolution and to correlate it with the in-reactor corrosion behavior at very high fluences. The materials examined in this study included two…
Recuperation increases the efficiency of a gas turbine engine by extracting heat from the exhaust gas stream and using it to pre-heat the compressor discharge air. High temperature oxidation and creep are major concerns, necessitating the use of heat-resistant alloys for the recuperator panels. Most current recuperato…
An attempt to improve the durability of the flame retardancy to washing of water soluble phosphate-based flame retardant on cotton fabric was studied. In this study, the poorly substantive phosphate treated fabric was further padded with chitosan solution. After drying, the chitosan formed film layer covering the fabr…
Supercritical carbon dioxide (scCO2) was utilized to impregnate ethyl methacrylate (EMA) and propyl methacrylate (PMA) monomers within an Ultra High Molecular Weight Polyethylene (UHMWPE) matrix where they were subsequently copolymerised in situ. The ratio of EMA to PMA was varied in the monomer feedstock in order to…
Metal complexes (Cu, VO, Zn, Mn, and Ni) with 5-alkoxy-, 5-alkoxycarbonyl-, 5-alkanoyloxy-, and 5-alkyl-tropolonato structures as well as bis(5-alkoxy-2-aminotroponato)copper were synthesized. All bistropolonato Cu complexes showed ordered smectic phases such as hexatic smectic B, smectic G(J), and smectic H phases. T…
A novel preparation method for core/shell nanoparticles with hydrophilic polymeric shell was designed and characterized. The core is composed of poly(lactide-co-glycolide) and polymeric shell is composed of pluronics (poly (ethylene oxide)-poly (propylene oxide)-poly(ethylene oxide) triblock copolymer, F-127) and hyal…
A novel phosphorus(V) porphyrin bearing two ptp[4'-(4-phenyloxy)-2,2'ratio6',2''-terpyridine] groups was prepared and modulation of the intramolecular PET (lambda(ex)= 566 nm) and PET --> EET (lambda(ex)= 300 nm) processes was studied from ptp to phosphorus(V) porphyrin by Zn2+ or Cd2+ ions.
We present calculations for the optical absorption spectra of hexagonal boron nitride (hBN) and BN nanotubes, using many‐body perturbation theory. Solution of the Bethe‐Salpeter equation for hBN leads to optical absorption and loss spectra where the positions and shapes of the peaks are strongly dominated by excitonic…
Surface structures of seven different commercial Si3N4 powders were investigated by X-ray photoelectron spectroscopy (XPS). The evaluated powders were produced by three different methods: diimide precipitation, carbothermal reduction and nitridation of silicon using different nitriding media with final treatments. The…
Abstract This article addresses dies and die materials used for hot forging in vertical presses, hammers, and horizontal forging machines (upsetters). It reviews the properties of die materials for hot forging, including good hardenability, resistance to wear, plastic deformation, thermal fatigue, and mechanical fatig…
X-ray powder diffraction is a standard technique in materials chemistry, yet it is often still used in the laboratory as a "one-hit" technique, e.g. for fingerprinting and following the progress of reactions. It is important, however, that the wealth of information available from powder data is not overlooked. While i…
P-type (Bi2Te3)x(Sb2Te3)1−x thermoelectric materials with various chemical compositions (x=0.16, 0.20 and 0.24) were fabricated through the zone melting (ZM) method and spark plasma sintering (SPS) technique. The dimensionless figure of merit (ZT=α2σT⁄κ) of the zone-melted crystals increased with increasing the Bi2Te3…