Solvent Extraction of Indium,Gallium, and Zinc Ions with Acidic Organophosphates having Bulky Alkyl Groups

The extraction equilibria of In³⁺, Ga³, and Zn²⁺ with bis(4‐ethylcyclohexyl)phosphoric acid (D4ECHPA), bis(4‐cyclohexylcyclohexyl)phosphoric acid (D4DCHPA), and bis(2‐ethylhexyl)phosphoric acid (D2EHPA) were investigated in acidic aqueous sulfate media. The order of extractability of metal ions is D4DCHPA > D2EHPA > D4ECHPA, which corresponds to the lipophilicity (log P) of the extractants. The separation factors, β_(In/Ga) and β_(Ga/Zn), of D4ECHPA and D4DCHPA are greater or comparable than that of D2EHPA, because of the steric hindrance of the bulky cyclohexyl groups. In³⁺ can be therefore separated from simulated liquor containing a high concentration of Zn²⁺ by D4DCHPA.     

The mechanism of atmospheric rusting and the protective amorphous rust on low alloy steel

Atmospheric rusting of mild and low alloy steels was studied by means of infra-red and far infra-red spectrophotometries, X-ray and electron diffraction methods and scanning electron microscopy. The rusting process can be interpreted on the basis of a previously reported diagram for rust formation in aqueous solution.A large amount of amorphous matter in rust formed in semi-rural atmosphere was identified by infra-red and far infra-red spectra as amorphous ferric oxyhydroxide, FeO_x (OH)_8–2x. The amorphous ferric oxyhydroxide rust on low alloy steel was dense and uniform, and contained a considerable amount of bound water. From these results it can be concluded that the amorphous ferric oxyhydroxide rust acts as a protective barrier against atmospheric rusting of the steels. Cu, P and Cr in low-alloy steels are inferred to favour the formation of crack-free, uniform rust layer and help to produce uniform amorphous ferric oxyhydroxide.     

Effect of CF/GF fibre hybrid on impact properties of multi-axial warp knitted fabric composite materials

The multi-axial warp knitted fabric (MWK) is a useful reinforcement for composite. Higher mechanical performance resulted from no crimp of the fibre bundle is achieved compared with the general textile composites. For the fibre bundle of MWK, only one type of reinforcement fibre among glass, carbon fibre bundle, and so on has been selected. The mechanical properties and the cost of MWK composite depend on the feature of the fibre bundle. In order to extend the applicability of composite, the concept of “fibre hybrid composite” was applied into the MWK composite. Two kinds of fibre bundle; carbon and glass, were used in the 0/90 multi-axial warp knitted fabric. As the fibre hybrid composite; the inter-layer hybrid composite in which each layer was fabricated by carbon and glass fibre bundle respectively was investigated. Impact properties of composite were investigated by using drop weight impact tests. In case of unsaturated polyester, total energy and progressive energy of inter-layer fibre hybrid composite realized the highest value in all specimens. However, in case of epoxy resin, inter-layer hybrid composite didn’t realize the highest value in all specimens. The difference in energy absorption capability could be described with the fracture mechanism.     

Characterization of oxygen-dependent lysis of Escherichia coli cells infected by bacteriophage T4

Infection of Escherichia coli cells by T4 phage at a multiplicity of infection (MOI) of 0.01 caused inhibition of cell lysis for up to 4 h. Such cells grown under aerobic condition were lysed by external stimuli such as cold shock, osmotic shock or addition of toxic substances, e.g., carbonyl cyanide m-chlorophenylhydrazone (CCCP). However, the effects of these external stimuli were reduced by transferring the cells to static incubation, by which dissolved oxygen was consumed by the cells within 10 min. The cells became insensitive to such external stimuli when the culture was deoxygenated with nitrogen gas. Following infection with a lysozyme amber mutant, eL1a, the cell membrane permeability was found to be increased either by cold shock or osmotic shock treatment of cells grown under aerobic conditions, but not in cells transferred to the static incubation. Oxygen limitation was suggested to enhance membrane stability in relation to cell lysis following the cold or osmotic shock treatment.     

An XPS study of the surfaces on Fe-Cr,Fe-Co and Fe-Ni alloys after mechanical polishing

Using an XPS technique, the composition and thickness of the surface film and the composition of the underlying alloy surface on Fe-Cr, Fe-Co and Fe-Ni alloys were studied after polishing with silicon carbide paper in trichloro-ethylene and cyclohexane. The compositions of the underlying alloy surface after polishing were almost the same as those of the bulk alloys but the film compositions depended on the alloying addition and environment during polishing. The cationic fractions in the surface films on the Fc-Cr alloys polished in both solvents were almost the same as the corresponding atomic fractions of the bulk alloys. In contrast, iron ions were apt to be concentrated in the surface films on the Fe-Co and Fe-Ni alloys, and the weights of nickel ions were different in the surface films on the Fe-Ni alloys polished in different solvents. Chloride ions were found in the surface films due to the reaction of the metal surface with trichloro-ethylene. The amount of chloride ions was particularly large in the surface films on the Fe-Ni alloys. Heating the alloy specimens under the vacuum of the spectrometer resulted in almost complete reduction of the surface films on the Fe-Co and Fe-Ni alloys, and in the change in the compositions of all alloy surfaces.     

Effects of passive smoking on the regulation of rat aortic cholesteryl ester hydrolases by signal transduction

The effects of exogenous oxidative stress due to passive smoking on cholesteryl ester (CE)-metabolizing enzymes and their regulatory kinases were examined by exposing rats to cigarette smoke (CS) for a 1-h period twice a day for 8, 12, or 20 wk. An oxidatively modified low density lipoprotein (Ox-LDL) with a high lipid peroxide was identified in three CS groups after all three exposure periods. The rat aortic acid and neutral CE hydrolases (ACEH and NCEH) were activated to similar extents by both cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) in the presence of their respective cofactors. The aortic PKC activity in the three CS groups exhibited significant reductions of 72, 84, and 75% as compared with the respective controls, which coincided with the reductions in the ACEH activities (86, 71, and 80%, respectively), whereas the PKA activities increased to 121, 197, and 252% in the three CS groups, respectively. Reflecting the increase of the PKA activity, the NCEH activity exhibited increases of 112% at 8 wk and 140% until 12 wk of exposure and decreased by 50% of the control value at 20 wk of exposure, suggesting inactivation of NCEH itself. The activation of acyl-CoA:cholesterol O-acyl-transferase activity was associated with an increase of free cholesterol in aorta. The vitamin E diet prevented the formation of Ox-LDL and the oxidative inactivation of most enzymes, especially PKC, until 12 wk, but was less effective by 20 wk. The oxidative inactivation of PKC, particularly its activated form that translocated to the membrane fraction, was confirmed in the in vitro exposure to active oxygen generators at an optimal concentration; this inactivation was prevented by catalase and superoxide dismutase. These results suggested that the formation of Ox-LDL and alterations in CE-metabolizing enzymes caused by passive smoking could contribute to a twofold increase in the aortic CE content, thereby contributing to one of the mechanisms for atherosclerosis associated with smoking.     

Microstructure and electrochemical behavior of Ti-coatedZr55Al10Ni5Cu30 bulk metallic glass

In this study, pure Ti was coated on Zr₅₅Al₁₀Ni₅Cu₃₀ bulk metallic glass (BMG) using a physical vapour deposition (PVD) technique with magnetron sputtering. Microstructures of Ti coating, BMG substrate and interface were investigated by conventional and high-resolution transmission electron microscopy (TEM and HREM). The electrochemical behavior of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG was studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in Hanks' solution. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the coating after electrochemical testing. HRTEM observation reveals that the sputtering Ti coating consists of α-Ti nano-scale particles with the size about 10 nm. The polarization curves revealed that the open-circuit potential shifted to a more positive potential and the passive current density was lower after Ti coating was applied in comparison with that of the monolithic Zr₅₅Al₁₀Ni₅Cu₃₀ BMG. Electrochemical impedance spectroscopy (EIS) measurements showed that the Bode plots of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG presented one time constant for 1 h and 12 h immersion and two time constants after 24 h immersion. The good bonding condition between Ti coating and Zr₅₅Al₁₀Ni₅Cu₃₀ BMG substrate may be responsible for the high corrosion resistance of Ti-coated Zr₅₅Al₁₀Ni₅Cu₃₀ BMG.     

Changes in the surface compositions of FeCr alloys caused by heating in a high vacuum

The change in the alloy surface by heating in a vacuum up to 380°C has been studied for a series of iron—chromium alloys by means of X-ray photo-electron spectroscopy (XPS). Remarkable enrichment of chromium occurs in surface films on the alloys containing 13 % chromium or more. Dependence of composition and thickness of film and composition of alloy surface directly beneath the film on alloy composition has been examined in detail and has been interpreted in terms of the oxidation of chromium and the conversion of the pre-existing surface film, such as decomposition of the oxyhydroxide-like structure and reduction of oxidized iron.