Microstructural Characterization of C60-Doped Zirconia

Zirconia powders doped with C₆₀ molecules were prepared from an aqueous solution of zirconium oxynitrate dihydrate, C₆₀ and C₁₆TMA, and sintered at 600°C under 5.5 GPa for 2 h. C₆₀ was found to be retained in the sintered specimens by HRTEM, and carbon was observed to be uniformly dispersed by the SEM-EDX analysis. HRTEM observations of the sintered specimens exhibited the formation of ZrO₂ crystal grains covered with thin graphitic or amorphous carbon films.     

The rapid,living, anionic polymerization of 2‐vinylnaphthalene at ambient temperature: Characterization of an n‐butyllithium/tetrahydrofuran system in 1,2,3,4‐tetrahydronaphthalene

We report the first well‐controlled room temperature anionic polymerization of 2‐vinylnaphthalene (2‐VNP), using alkyllithium (RLi) initiators. The nucleophilicity and solubility of the RLi as well as that of the 2‐vinylnaphthalenyllithium (VNPLi) and poly(2‐vinylnaphthalenyl)lithium (PVNPLi) propagating species were found to be very important factors in this reaction. An initiator system composed of n‐butyllithium (n‐BuLi) with tetrahydrofuran (THF) in 1,2,3,4‐tetrahydronaphthalene (THN) was determined to be the most effective of the various systems examined. The n‐BuLi/THF complex initiates polymerization and the resulting VNPLi/THF and PVNPLi/THF complexes act as propagating species at room temperature. These species offer adequate nucleophilicity and stability without promoting side reactions. As a result, rapid anionic polymerization was achieved. Various poly(2‐VNP) products with well‐defined polymeric chain structures were synthesized by this process at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41901.     

Multi-shot flash lamp annealing method for electroless-plated Ni-P film on UV-surface-modified ABS

The multi-shot flash lamp annealing (FLA) method as a rapid annealing technique was developed for an electroless-plated Ni-P film on UV-surface-modified acrylonitrile–butadiene-styrene (ABS) in place of the conventional annealing method. The new multi-shot FLA method continuously irradiates a Xe flash discharge with low irradiance (<1?J?cm^–2) with a frequency of 3?Hz. An adhesion strength between the electroless Ni-P film and ABS of more than 1.2?kN?m^–1 was achieved in a short time of approximately 30?s; this adhesion strength was larger than that obtained in the conventional method of 1?h duration. The etching effect of the FLA method was assessed by a study of the surface morphologies of the Ni-P films. XRD spectra of the Ni-P films showed an improvement in the crystallinity of the films. Considering surface elemental analyses of the peeled Ni-P-film/ABS, a cohesive failure, which implies high adhesion, was observed in the ABS. The proposed FLA method is expected to efficiently improve the adhesion and significantly reduce the annealing time in the electroless plating process.     

Prevention of Cracks in Functionally Graded SiO2‐Mo Materials Fabricated by Uniaxial Compression Casting and Pressureless Sintering

In industrial high‐intensity discharge lamps, cracks and delaminations occasionally develop at the interface between SiO₂ and the Mo foil in the seal. Here, functionally graded SiO₂‐Mo materials for use in these lamps were fabricated by uniaxial compression casting and pressureless sintering. Consequently, vertical cracks developed across the sintered body layers, and interfacial cracks developed between the 100 wt% SiO₂ and 90 wt% SiO₂‐Mo layers. Therefore, the effects of residual stress, difference in the coefficient of thermal expansion (CTE), and difference in the volume shrinkage on these cracks were investigated. Vertical cracks were suppressed when residual stress was relaxed by annealing near the annealing point of silica glass during the cooling step in the sintering process. Interfacial cracks were suppressed when the difference in the CTE of the interface between the 100 wt% SiO₂ and 90 wt% SiO₂‐Mo layers was relaxed by inserting layers of 95 wt% SiO₂‐Mo between them. Furthermore, the suppression effect became stronger when the difference in the volume shrinkage of the layers was relaxed by sintering to join the separately sintered monolayers. Thus, the development of these cracks was influenced by the residual stress, CTE, and volume shrinkage. Therefore, these cracks can be prevented by optimizing these factors.     

Formation Behavior and High Electrical Conductivity of Metastable Lithium Iron Silicate Crystals in Rapid Quenching of Li2O–Fe2O3–SiO2 Melts

The formation behavior of spinel‐type LiFeSiO₄ crystals in the quenching of melts in the Li₂O–Fe₂O₃–SiO₂ system was examined. It was found that high quenching rates of 10³ ~ 10⁶ K/min are favorable for the formation of LiFeSiO₄ crystals. The rapid quenched samples showed high electrical conductivities of the order of 10^?2–10^?4 S/cm at room temperature and low activation energy for conduction of 0.1–0.2 eV. Both valences of Fe²⁺ and Fe³⁺ were present in the melt‐quenched samples, and rapid‐quenched samples showed ferrimagnetism. It is proposed that the chemical composition of LiFeSiO₄ formed in the rapid quenching of melts would be spinel‐type Li_1 + xFe³⁺_1 ? xFe²⁺_xSiO₄. Because the Li_1 + xFe³⁺_1 ? xFe²⁺_xSiO₄ crystalline phases are metastable, the rapid quenching technique is necessary for their synthesis. The effects of quenching rate and composition on the formation of spinel‐type LiFeSiO₄ and on the electrical conductivity of quenched samples were discussed.     

The influence of interlayer molecules in luminescence of self-assembled bilayer PbS quantum dot films

We synthesized organic solvent-soluble and water-soluble PbS quantum dots (QDs) with different sizes. The organic solvent-soluble PbS QDs dispersed in tetrachloroethylene were used to prepare bilayers structures of QDs bound by dithiol linkers on GaAs. The water-soluble PbS QDs were used to prepare bilayer structures of QDs on quartz based on alternating adsorption of polyelectrolyte. For bilayer films on GaAs, it was found that the stacking sequence of QDs affects the quantum yield and emission wavelength of the larger QDs. However, for bilayer films with different stacking sequences on quartz, the larger QDs show similar PL intensities and emission wavelength independent of the sequence. The probable mechanism for this difference observed is discussed in terms of charge transfer between QDs.     

Expression and purification of recombinant human annexin A2 in Pichia pastoris and utility of expression product for detecting annexin A2 antibody

Annexin A2, a Ca2+-dependent phospholipid binding protein, is abundantly expressed in various human organs, which exists as either a membrane-associated, cytosolic or soluble form in serum. We constructed expression systems for recombinant human annexin A2 (rhA2) using Pichia pastoris. The systems are designed to secrete rhA2 as either the N- or C-terminally His6-tagged form to facilitate purification. Both types of rhA2 were overexpressed, but in the N-terminal-truncated form as revealed from the results of N-terminal amino acid sequencing and Western blotting. Therefore, further purification of N-terminally His6-tagged rhA2 was not feasible because of the removal of the N-terminal His6-tag sequence. C-terminally His6-tagged rhA2 was expressed as either a glycosylated or a nonglycosylated form, and the nonglycosylated form was purified using the combination of nickel-immobilized affinity, concanavalin A and cation exchanged column chromatographies. The solid-phase binding of rhA2 was examined by enzyme-linked immunosorbent assay (ELISA), which revealed the specific reactivity of rhA2 against an anti-annexin A2 monoclonal antibody. These results suggest that the expression system using P. pastoris is useful for the preparation of rhA2 that is applicable to the ELISA detection of the anti-annexin A2 antibody.     

Functional Qbeta replicase genetically fusing essential subunits EF-Ts and EF-Tu with beta-subunit

Qbeta replicase, an RNA-dependent RNA polymerase of RNA coliphage Qbeta, is a heterotetramer composed of a phage-encoded beta-subunit and three host-encoded proteins: the ribosomal protein S1 (alpha-subunit), EF-Tu, and EF-Ts. Several purification methods for Qbeta replicase were described previously. However, in our efforts to improve the production of Qbeta replicase, a substantial amount of the beta-subunit overproduced in Escherichia coli cells was found as insoluble aggregates. In this paper, we describe two kinds of method of producing Qbeta replicase. In one kind, both EF-Tu and EF-Ts subunits were expressed with the beta-subunit, and in the other kind, the beta-subunit was genetically fused with EF-Tu and EF-Ts. The fused protein, a single-chain alpha-less Qbeta replicase, was mostly found in the soluble fraction and could be readily purified. These results pave the way for the large-scale production of the highly purified form of this enzyme.     

Inhibitory effects of diazepam and midazolam on Ca2+ and K+ channels in canine tracheal smooth muscle cells

BACKGROUND: Benzodiazepines have a direct bronchodilator action in airway smooth muscle, but the mechanisms by which these agents produce muscle relaxation are not fully understood. The current study was performed to identify the effects of the benzodiazepines diazepam and midazolam on Ca2+ and K+ channels in canine tracheal smooth muscle cells. METHODS: Whole-cell patch-clamp recording techniques were used to evaluate the effects of the benzodiazepines diazepam (10(-8) to 10(-3) M) and midazolam (10(-8) to 10(-3) M) on inward Ca2+ and outward K+ channel currents in dispersed canine tracheal smooth muscle cells. The effects of the antagonists flumazenil (10(-5) M) and PK11195 (10(-5) M) on these channels were also studied. RESULTS: Each benzodiazepine tested significantly inhibited Ca2+ currents in a dose-dependent manner, with 10(-6) M diazepam and 10(-5) M midazolam each causing approximately 50% depression of peak voltage-dependent Ca2+ currents. Both benzodiazepines promoted the inactivated state of the channel at more-negative potentials. The Ca2+-activated and voltage-dependent K+ currents were inhibited by diazepam and midazolam (> 10(-5) M and > 10(-4) M, respectively). Flumazenil and PK11195 had no effect on these channel currents or on the inhibitory effects of the benzodiazepines. CONCLUSIONS: Diazepam and midazolam had inhibitory effects on voltage-dependent Ca2+ channels, which lead to muscle relaxation. However, high concentrations of these agents were necessary to inhibit the K+ channels. The lack of antagonized effects of their antagonists is related to the non-gamma-aminobutyric acid-mediated electrophysiologic effects of benzodiazepines on airway smooth muscle contractility.