Processing low-grade oxidized coal to produce effective carbon sorbents

High-porosity sorbents may be produced by carbonization of low-grade oxidized coal in the presence of alkali.     

Liquid phase growth of graphene on silicon carbide

We developed a novel method to produce graphene on silicon carbide (SiC) at a temperature as low as 1000 °C. The method is based on liquid phase growth (LPG) of graphene mediated by liquid gallium, which acts not only as a flux to store carbon dissolved from a surface of SiC when heated, but also as a catalyst to promote the formation of graphene on SiC when cooled. Our experimental results revealed that gallium-treated SiC substrates are coated with uniform and continuous graphene films. The LPG method is able to supply graphene films consisting of one to several hundreds of layers, depending on heating temperatures. Our approach can not only provide an alternative way to form graphene natively on SiC, but will also bring a technological breakthrough in industrial applications of graphene, e.g. the realization of graphene-on-insulator substrates.     

Charge state of copper ions in the YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>6.8</Subscript> single crystal (1.5 at % Ce): X-ray photoelectron and absorption studies

X-ray photoelectron and absorption spectra of YBa₂Cu₃O_6.8 single crystals (1.5 at % Ce) annealed in vacuum, in argon, and in air have been studied. It has been established that the heat treatment in air at 200°C for 100 h led to the appearance of Cu₁₊ ions in a subsurface layer and to an increase in the degree of covalence of the Cu-O bonds in the “bulk” of the sample.     

Serum and urine metal levels in patients with metal-on-metal surface arthroplasty

The resurgence of metal-on-metal articulating surfaces for hip arthroplasty has also heightened concerns about the degree and magnitude of metal particle generation and the accompanying increase in circulating metal ion concentrations. In this study, we measured the concentration of chromium in serum and urine and the concentration of cobalt in serum in twenty-five patients with modern metal-on-metal surface arthroplasty of the hip in a prospective manner. The results showed that the mean post-operative chromium in serum levels were 22-fold, 23-fold and 21-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative cobalt in serum levels were 8-fold, 7-fold and 6-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative chromium in urine levels were 9-fold, 10-fold and 14-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The values seen in this study with the current generation of surface arthroplasties are: (a) lower than those seen in an earlier generation of surface arthroplasties; (b) in the same range as those observed in association with metal-on-metal conventional total hip replacements, which typically have smaller head sizes; (c) higher than values observed in patients with conventional metal-on-polyethylene articulating couples.     

Radiation-chemical synthesis of poly(vinyl alcohol) hydrogel containing dicyclohexano-18-crown-6

Radiation-chemical synthesis of poly(vinyl alcohol) hydrogels containing physically immobilized dicyclohexano-18-crown-6 was carried out. Remarkable gel fraction of 40-70% was observed at absorbed dose of about 5 kGy. Increasing degree of poly(vinyl alcohol) crosslinking led to growth of the efficiency of crown ether immobilization. Post-irradiation thermal annealing of the hydrogel samples at 120 °C for 0.5-5 h resulted in an increase of crown ether retention as compared with non-annealed samples by approximately 20% at the same absorbed dose. Preliminary results on a sorption behavior of the crown-containing hydrogels with respect to Sr²⁺ cations in 2.4 M HNO₃ solution are presented.     

Ti-TiNi-HfNi-Hf Liquidus surface

Physical and chemical analysis methods are used for the first time to examine the Ti-TiNi-HfNi-Hf alloys in the melting-crystallization region. The liquidus surface is shown to consist of six fields of primary phase crystallization: λ₁, η, δ, θ, β, and α. The largest fields are of δ-and β-phases. The λ₁ ternary phase is formed by peritectic reaction l + δ → λ₁. There are five invariant equilibria involving liquid on the Ti-TiNi-HfNi-Hf solidus surface. The liquidus surface, vertical sections, and alloy crystallization scheme are constructed.     

Creep of oksalon fibres in aqueous sulfuric acid solutions

Conclusions Oksalon yarns do not display an accumulation of plastic deformations in sulfuric acid solutions in stretching in a creep regime, up to a concentration of about 80% by wt.The equilibrium reversible deformation which is reached under conditions of constant tension has a maximum at a sulfuric acid content in the solution of about 70%, and a minimum at 72–73%.The characteristic changes in deformation properties of yarns as a function of the sulfuric acid content of the stretching medium are explained by structural changes which occur in the polyoxadiazole.Stretching Oksalon yarns in a 75% sulfuric acid solution leads to a 25–30% rise in the strength of washed and dried yarnsTranslated from Khimicheskie Volokna, No. 6, pp. 34–36, November–December, 1984.