A thousandfold creep strengthening by Ca addition in die-cast AM50 magnesium alloy

The effect of calcium addition on the microstructure and creep strength of the die-cast AM50 magnesium alloy was investigated. The α-Mg grains with the diameter of 4.9 μm are surrounded by the eutectic phases for the AM50-1.72 mass pct Ca alloy, while the β(Mg₁₇Al₁₂) particles are located mainly on the grain boundaries of the α grains for the AM50 alloy. The minimum creep rates of the AM50-1.72 mass pct Ca alloy are three orders of magnitude lower than those of the AM50 alloy at 423 K typically below 120 MPa. The thousandfold creep strengthening by the Ca addition is ascribed to the thermally stable eutectic phases appearing in the AM50-1.72 mass pct Ca alloy, which is expected to yield effective grain boundary strengthening or to resist the plastic flow of the α-Mg grains.     

Evaluation of molecular orientation and alignment of poly(3-hexylthiophene) on Au (111) and on poly(4-vinylphenol) surfaces

The orientation and alignment of regioregular poly(3-hexylthiophene) (P3HT) molecules on Au (111) surface and on poly(4-vinylphenol) (PVP) thin film were investigated. The P3HT molecules on the smooth Au (111) are oriented with both the backbones and the side chains parallel to the substrate (plane-on orientation) as revealed by the scanning tunneling microscope (STM) images. However, the P3HT molecules on the PVP thin films are preferably oriented with side chains perpendicular to the surface (edge-on orientation). Surface modification of the PVP by hexamethyldisilazane (HMDS) can increase the crystalline size in the P3HT semicrystalline films. The performance of an all-polymer organic field-effect transistor (OFET) with the drop-cast P3HT semiconductor layer and the crosslinked PVP gate insulator on poly(ethylene naphthalate) (PEN) substrate was evaluated.     

Preparation and characterization of magnetically separable photocatalyst (TiO2/SiO2/Fe3O4): effect of carbon coating and calcination temperature

TiO2/SiO2/Fe3O4 composite was synthesized by sol-gel technique for silica and titania coatings on magnetite core to enable recovery after photocatalytic degradation. Carbon coating was also carried out by calcination of TiO2/SiO2/Fe3O4 under nitrogen atmosphere in presence of PVA as a source of carbon to enhance the adsorption of organic compounds on catalyst surface and to get better activity. All prepared samples were characterized using EDX, CN analyzer, XRD, BET and SEM. Degradation of methyl orange dye was used to assess the photocatalytic performance of the prepared samples. Calcination temperature was found to affect rate of reaction because of the formation of rutile phase at high calcination temperature. Carbon coated samples unexpectedly exhibited lower rate of reaction at almost all calcination temperatures.     

Feasibility of direct oxygenation of primary-cultured rat hepatocytes using polyethylene glycol-decorated liposome-encapsulated hemoglobin (LEH)

We tested the short-term efficacy of liposome-encapsulated hemoglobin (LEH) in cultured rat hepatocytes. Supplementation with LEH (20% of the hemoglobin concentration of blood) did not lower albumin production in static culture, and completely reversed the cell death and deterioration in albumin production caused by an oxygen shortage in 2D flat-plate perfusion bioreactors.     

Bioaccumulation profiles of S-labelled sodium alkylpoly(oxyethylene) sulfates in carp (Cyprinus carpio)

The uptake, distribution and elimination of two labelled surfactants, ³⁵S-labelled sodium dodecyltri(oxyethylene) sulfate (³⁵S-C12-AES(3)) and ³⁵S-labelled sodium dodecylpenta(oxyethylene) sulfate (³⁵S-C12-AES(5)) were investigated in carp (Cyprinus carpio) exposed to concentrations of 0.3–0.6 mg l⁻¹, using whole-body autoradiography and the liquid scintillation counting method. ³⁵S-Radioactivity was first rapidly absorbed by the gills and skin and transferred to other organs and tissues. After 24 h-exposure, there was a comparatively high accumulation of ³⁵S-radioactivity in the gills, hepatopancreas, gall bladder, intestinal content, and nasal and oral cavity. The distribution patterns of ³⁵S-radioactivity derived from ³⁵S-C12-AES(3) and ³⁵S-C12-AES(5) in tissues and organs were similar. The whole-body concentration factors of ³⁵S-radioactivity in fish exposed to ³⁵S-C12-AES(3) and ³⁵S-C12-AES(5) for 72 hr were 18 and 4.7, respectively. In surfactant-free water, the absorbed ³⁵S-radioactivity was eliminated more rapidly from the fish body exposed to ³⁵S-C12-AES(3) than ³⁵S-C12-AES(5). It was eliminated relatively fast from gills and hepatopancreas, but elimination from gall bladder was rather slow.     

Synergic effect of vanadium trichloride on the reversible hydrogen storage performance of the MgMgH2 system

Vanadium trichloride (VCl₃) is one of the best catalysts for the hydrogenation-dehydrogenation MgMgH₂ system. X-ray photoelectron spectroscopy (XPS) has shown that VCl₃ reduced to metallic vanadium during ball milling along with MgH₂. The in-situ-formed metallic vanadium doped over the MgH₂ surface which has shown an excellent catalytic effect on hydrogenation-dehydrogenation of the MgMgH₂ system. The catalyzed surface reduced the activation energies of hydrogenation-dehydrogenation reactions and correspondingly on-set hydrogenation-dehydrogenation temperatures. The microstructural analysis has also shown an excellent grain refinement property of VCl₃ which reduced the crystallite size of MgH₂. The decreased crystallite size decreases the diffusion path length of hydrogen and increases the active surface area which eventually enhances the hydrogenation-dehydrogenation kinetics of MgMgH₂.     

Remarkably improved dehydrogenation of ZrCl4 doped NaAlH4 for hydrogen storage application

Thermal dehydrogenation kinetics of sodium alanate (NaAlH₄) has been studied with respect to ZrCl₄ additive, and the results were compared with pure NaAlH₄. The FTIR analysis has shown insignificant effects of ZrCl₄ on the structural integrity of AlH₄^? anion after ball milling. Partial reduction of ZrCl₄ has been observed during ball milling with NaAlH₄. The in-situ reduction favors to homogeneous and adherent dropping of ZrCl₄ over the NaAlH₄ surface which leads to remarkably improved dehydrogenation process. The dehydrogenation of ZrCl₄ doped NaAlH₄ occurred in three steps similar to pure NaAlH₄. The dehydrogenation temperatures of all the steps were substantially decreased as compared to pure NaAlH₄. The apparent activation energy of dehydrogenation of ZrCl₄ doped NaAlH₄ was evaluated for all the dehydrogenation steps and found to be significantly less with respect to pure NaAlH₄.     

Iridescence of 2‐hydroxyethyl methacrylate/aromatic allyl ester reaction mixtures

Reaction of 2‐hydroxyethyl methacrylate and diallyl phthalate or vinyl 4‐tert‐butylbenzoate has been found to give an iridescent reaction mixture. Transmittance spectra of the reaction mixture depended on the temperature in the range of 0 to 60°C. The temperature‐transmittance curves showed a discrete stepwise change near the room temperature. Polymerization reaction of 2‐hydroxyethyl methacrylate (PHEMA) in a nonreactive monomer substitute, dipropyl phthalate, showed a temperature dependence as was seen for the iridescent reaction mixture, but was not iridescent. PHEMA suspension in several aromatic solvents also showed iridescence, and some of them were temperature dependent. The mechanism of temperature‐dependent iridescence of the copolymerization reaction mixtures is discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 125–131, 1999     

In-Plane Optical Spectra of Optimally-Doped LSCO Single Crystals

The in-plane optical spectra of an optimally doped La_1.85Sr_0.15CuO₄ single crystal were investigated over a wide range of frequency 8–30000 cm^–1, including a submillimeter wavelength region. While the in-plane conductivity shows a depression below 150 cm^–1 for T<T _c, which can be the signature of a gap formation, the spectral weight transferred to superfluid condensate is found to amount only to 48% at most of the value estimated from a London penetration depth in muon spin rotation study, suggesting the kinetic energy-driven superconductivity in this system.