SOLVENT EXTRACTION OF ZINC FROM CHLORIDE MEDIA WITH SECONDARY LONG-CHAIN ALKYLAMINE

In the solvent extraction of zinc from chloride media with a secondary long-chain alkylamine, Amberlite LA-2, aggregations of ammonium chloride salt of alkylamine and zinc-complex with alkylamine and distribution equilibrium of zinc were investigated at 30 "C using n-hexane as a diluent. The ammonium chloride salt of alkylamine exists as monomeric, dimeric, trimeric and tetrameric species (BHCl, (BHCl)₂, (BHCl)₃ and (BHCl)₄, respectively). The zinc-complex exists as monomeric and dimeric species ((BH)₂ZnCl₄ and ((BH)₂ZnCl₄)₂, respectively). Zinc is extracted according to the extraction reaction in the lower loading region of zinc to alkylamine and according to the extraction reaction in the higher loading region.     

Regio‐ and Stereochemical Controlled Koenigs–Knorr‐Type Monoglycosylation of Secondary Hydroxy Groups in Carbohydrates Utilizing the High Site Recognition Ability of Organotin Catalysts

The catalytic regio‐ and stereoselective monoglycosylation of carbohydrates using organotin catalysts is demonstrated. The one‐step reaction affords various oligosaccharides linked at the secondary hydroxy group in high chemical yield and good regio‐ and stereoselectivities. The regioselectivity of the glycosylation is shown to depend on the spatial arrangement of the hydroxy groups in the carbohydrates.

     

Immunomodulatory Properties and Osteogenic Activity of Polyetheretherketone Coated with Titanate Nanonetwork Structures

Polyetheretherketone (PEEK) is a potential substitute for conventional metallic biomedical implants owing to its superior mechanical and chemical properties, as well as biocompatibility. However, its inherent bio-inertness and poor osseointegration limit its use in clinical applications. Herein, thin titanium films were deposited on the PEEK substrate by plasma sputtering, and porous nanonetwork structures were incorporated on the PEEK surface by alkali treatment (PEEK-TNS). Changes in the physical and chemical characteristics of the PEEK surface were analyzed to establish the interactions with cell behaviors. The osteoimmunomodulatory properties were evaluated using macrophage cells and osteoblast lineage cells. The functionalized nanostructured surface of PEEK-TNS effectively promoted initial cell adhesion and proliferation, suppressed inflammatory responses, and induced macrophages to anti-inflammatory M2 polarization. Compared with PEEK, PEEK-TNS provided a more beneficial osteoimmune environment, including increased levels of osteogenic, angiogenic, and fibrogenic gene expression, and balanced osteoclast activities. Furthermore, the crosstalk between macrophages and osteoblast cells showed that PEEK-TNS could provide favorable osteoimmunodulatory environment for bone regeneration. PEEK-TNS exhibited high osteogenic activity, as indicated by alkaline phosphatase activity, osteogenic factor production, and the osteogenesis/osteoclastogenesis-related gene expression of osteoblasts. The study establishes that the fabrication of titanate nanonetwork structures on PEEK surfaces could extract an adequate immune response and favorable osteogenesis for functional bone regeneration. Furthermore, it indicates the potential of PEEK-TNS in implant applications.     

Characterization of anisotropic gas permeability and thermomechanical properties of highly textured porous alumina

Porous alumina with a highly textured microstructure was fabricated by pulse electric current sintering (PECS) using alumina platelets. Highly oriented porous alumina with a porosity of 3%–50% was obtained by a pressure-controlled method of PECS. The properties of the highly textured porous alumina were measured in two directions. The nitrogen gas permeance and thermal conductivity at room temperature were higher in the direction along the platelet length due to the higher continuity of pores and the connectivity of alumina platelets, respectively. The anisotropy of the thermal conductivity at room temperature was investigated and explained by the effect of grain size of platelets as well as morphology and orientation of pores. The bending strength was higher with the loading direction along the platelet thickness. The thermal shock strength was clearly different in the two directions. The difference in the thermal shock strength was investigated by the measurement of properties and thermal stress analysis.     

A negative resist for KrF excimer laser lithography

The design and preparation of a series of negative resists for KrF excimer laser lithography are described. Each resist is composed of poly(hydroxystyrene) and an aromatic azide. The base resin shows high transmittance of 62%/μm at 248 nm, when p-ethylphenyl p-azidophenylsulfonate. 4-azido-4α-methoxy-chalcone, 1-(4 azidobenzylidene)-3-(α-hydroxy-4-azidobenzyl)-indene, 4,4α-diazido-3,3α-dimethoxybiphenyl, or 1-(4-azidostyryl)-5, 5-dimethyl-2-cyclohexen-1-one is employed as a sensitizer. These azides are obtained by red-shifting the absorption maxima to lower energy regions than the exposing wavelength of 248 nm. Transmittance of resists can be controlled from 10 to 30%. The resist is exposed with a KrF excimer laser stepper and developed in an alkaline solution. Sensitivities of about 15 mJ/cm² are observed. A good, subhalf-micron resist profile is achieved. The photochemical reaction mechanisms of poly(hydroxystyrene) and 4,4α-diazido-3,3α-dimethoxybiphenyl were studied at 248 nm and 313 nm exposure. Quantum yield for photodecomposition at 248 nm is seven times larger than that at 313 nm, but dissolution-inhibition effects are larger at 313 nm exposure. Consequently, the resist shows higher sensitivity at 313 nm than at 248 nm.     

Formation Mechanism and Synthesis of Apatite-Type Structure Ba2+xLa8−x(SiO4)6O2−δ

The formation process of Ba₂La₈(SiO₄)₆O₂ was clarified using thermogravimetry–differential thermal analysis (TG-DTA) and a high-temperature powder X-ray diffraction (HT-XRD) method. Phase changes identified from the HT-XRD data surprisingly corresponded to the weight loss and/or endothermic peaks observed in the TG-DTA curves. Raw material with the composition Ba₂La₈(SiO₄)₆O₂ was completely reacted at 1400°C and produced only an apatite-type compound without a secondary phase. Moreover, the synthesis of Ba_{2+ x} La_{8− x} (SiO₄)₆O_2−δ crystals with x = 0–2 was attempted using a solid-state reaction.     

Dynamic in situ observation of automotive catalysts for emission control using X-ray absorption fine structure

Two main pivotal subjects of research in automotive catalysts were studied by modern X-ray absorption analysis techniques. One is oxygen storage/release behaviour, and the other is sintering inhibition of Pt particles. First, three types of CeO₂–ZrO₂ (Ce:Zr = 1:1 molar ratio) compounds with different oxygen storage/release capacities and different structural properties were prepared, and the valence change of Ce as a function of temperature during oxygen release/storage processes was investigated. The reduction of surface Ce mainly occurred in the range 100–170 °C, and the reduction of bulk Ce progressed at high temperatures of 170 °C and above. The Ce reduction behaviour depended not only on the homogeneity of the Ce and Zr for bulk reduction at high temperatures but also on the particle size of the CeO₂–ZrO₂ samples for surface reduction at low temperatures. Secondly, sintering inhibition of Pt in Pt/Al₂O₃, Pt/MgO and Pt/ceria-based catalysts after 800 °C ageing in air was studied. We found that the Pt–O–M (M = Mg, Ce) bond acted as an anchor and inhibited the sintering of Pt particles on MgO or ceria-based oxide. Especially, it was noteworthy that the Pt–O–Ce⁴⁺ bond on the ceria-based support breaks easily through the reduction of Ce (Ce⁴⁺ → Ce³⁺) during the usual stoichiometric and reducing conditions.     

Gravity consolidation-sedimentation behaviors of concentrated TiO2 suspension

Consolidation-sedimentation behaviors of consolidated sediment under action of gravity were investigated using highly concentrated suspension of titanium dioxide particles under conditions of various pHs, initial heights, and initial concentrations. The average consolidation ratio of the consolidated sediment was analyzed on the basis of the simplified analytical solution obtained using the modified Terzaghi's model under the moving Lagrangian coordinate system. Although the solution pH strongly affects consolidation-sedimentation behaviors, the modified average consolidation coefficient was little influenced by the solution pH. Also, the consolidation coefficient increased in almost direct proportion to the total volume of solids per unit cross-sectional area, which changes the driving force of consolidation-sedimentation due to the overlying weight of the solid particles. The variations with time of the height of the consolidated sediment were adequately described using the analytical solution describing the average consolidation ratio with the aid of the relation that the equilibrium height was represented by a power function of the total volume of solids for a specified pH.     

Direct synthesis of H2O2 acid solutions on carbon cathode prepared from activated carbon and vapor-growing-carbon-fiber by a H2/O2 fuel cell

Direct synthesis of H₂O₂ acid solutions was studied using a gas-diffusion cathode prepared from activated carbon (AC), vapor-growing-carbon-fiber (VGCF) and poly-tetra-fluoro-ethylene (PTFE) powders, with a new H₂/O₂ fuel cell reactor. O₂ reduction to H₂O₂ was remarkably enhanced at the three-phase boundary (O₂(g)-electrode(s)-acid(l)) at the [AC + VGCF] cathode. Fast diffusion processes of O₂ to the active surface and of H₂O₂ to the bulk acid solutions were essential for H₂O₂ accumulation. Synergy of AC and VGCF was observed for the H₂O₂ formation. RRDE and cyclic voltammetry studies indicated that the surface of AC functioned as the active phase for O₂ reduction to HO₂, and VGCF functioned as an electron conductor and a promoter to convert HO₂ to H₂O₂. A maximum H₂O₂ concentration of 353 mM (1.2 wt%) was accomplished under short-circuit conditions (current density 12.7 mA cm⁻², current efficiency 40.1%, geometric area of cathode 1.3 cm², reaction time 6 h).