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[en] Highlights: • Core-shell (BiO)2CO3@Bi2S3 nanowires are prepared and characterized in detail. • (BiO)2CO3@Bi2S3 nanowires show strong PL emission from violet to blue light range. • The sulfur content in (BiO)2CO3@Bi2S3 core-shell nanowires affect their PL emissions. • The growth mechanism of the core-shell nanowires relies on the ion-exchange reaction.
[en] The composition and properties of heavy residues of Israeli shale oil (S content 6.8 %) were investigated as a source for bitumens. Both principal methods of asphalt production - vacuum distillation and oxidizing with air -were studied. Straight-run bitumen had satisfactory characteristics. As to oxidized bitumen, the values of its penetration, ductility and softening point were also satisfactory. The drawback of shale oil bitumens is their high viscosity after the thin film oven test, which means their high sensitivity to aging. The shale oil composition changes significantly as a result of distillation and oxidation. The content of asphaltenes sharply increases: from 3.5 to 20-22 % in straight-run bitumen and to 30 % in oxidized bitumen. It is explained by the reactions of condensation and polymerization of the most unstable polar components during heating and oxidation. Unlike petroleum, shale oil is a product of pyrogenic origin, i.e., it is formed as a result of thermal decomposition of large molecules of kerogen and a part of this cracked material consists of unstable fragments of these molecules, which have a tendency to polymerization. The C/H ratio and nitrogen content increase significantly in the order 'saturated hydrocarbons-naphthenoaromatics - aromatics - asphaltenes'. (author)
[en] To understand the corrosion behavior of L80 steel in different temperature and sulfur content, the experiment which simulated the downhole corrosive environment was conducted. From the experiment result, when other factors were constant, the lowest corrosion rate was appeared when the temperature was 90°C. The influence of sulfur was complex. When temperature was low, the corrosion rate was decreased with the increase of sulfur content and the experimental result was opposite when temperature was high. (paper)
[en] The v-sharp grooving corrosion of ERW(electrical resistance welding) steel pipes limited their wide application in the industry in spite of their high productivity and efficiency. The grooving corrosion is caused mainly by the different microstructures between the matrix and weld that is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. Even though the diminishing of sulfur content is most effective to decrease the susceptibility of grooving corrosion, it requires costly process. In this study, improvement of grooving corrosion resistance was pursuited by post weld heat treatment in the temperature range between 650 .deg. C and 950 .deg. C. Also, the effect of heat input in the welding was investigated. By employing chromnoamperometry and potentiodynamic experiment, the corrosion rate and grooving corrosion index(α) were obtained. It was found that heat treatment could improve the grooving corrosion resistance. Among them, the heat treated at 900 .deg. C and 950 .deg. C had excellent grooving corrosion resistance. The index of heat treated specimen at 900 .deg. C and 950 .deg. C were 1.0, 1.2, respectively, which are almost immune to the grooving corrosion. Potential difference after the heat treatment, between base and weld metal was decreased considerably. While the as-received one measured 61∼71 mV, that of the 900 .deg. C heat treated steel pipe measured only 10mV. The results were explained and discussed
[en] Highlights: • Metallic and polar Co9S8 nanocrystals inlaid carbon (Co9S8/C) hollow nanopolyhedra as sulfur host have been prepared. • The Co9S8/C hollow nanopolyhedra can ensure the loading mass and buffer the volume expansion of sulfur during cycling. • The Co9S8/C shell offers synergetic spatial confinement and chemical binding to prevent the shutting effect. Lithium−sulfur (Li−S) batteries are promising to replace current commercial Li−ion batteries due to the high energy density. Despite this, the poor cyclic stability induced by the shuttle effect of electrolyte-soluble intermediate polysulfides is one of the great obstacles for the application of Li−S batteries. To overcome this issue, here we report a self-template synthesis of metallic and polar Co9S8 nanocrystals inlaid carbon (Co9S8/C) hollow nanopolyhedra as an efficient sulfur host material. The Co9S8/C hollow nanopolyhedra with large inner space can ensure the loading mass of sulfur and buffer the volume expansion of Li2Sx species during cycling; while the metallic and polar Co9S8/C shell offers synergetic spatial confinement and chemical binding to immobilize polysulfides and prevent the shutting effect. The Co9S8/C-S composite cathode exhibits high capacity and long cycle life with a low capacity decay of 0.041% per cycle over 1000 cycles at 2.0 C. When the areal sulfur content is as high as 3.0 mg cm–2, the Co9S8/C-S cathode still maintains high cycling stability.
[en] Fatigue crack growth test of low alloy steel was performed in high temperature water. Test parameters were dissolved oxygen content, loading frequency and R-ratio (Pmm/Pmax). Since the sulfur content of the steel was low, there were no environmentally assisted cracks (EAC) in low dissolved oxygen(DO) water. At high DO, the crack growth rate at R = 0.5 tests was much increased due to environmental effects and the crack growth rate depended on loading frequency and maximized at a critical frequency. On the other hand, R = 0.7 test results showed an anomalous decrease of the crack growth rate as much different behavior from the R = 0.5. The main reason of the decrease may be related to the crack tip closure effect. All the data could be qualitatively understood by effects of oxide rupture and anion activity at crack tip
[en] The cyanobacteria Prochlorococcus is a cyanbacterial genus, with some strains adapted to sea surface environments, which are poor in nutrients and have high-light intensity, and some strains adapted to deep sea conditions, which have relatively higher concentrations of nitrogen and phosphorus and lower light intensity. Here, we report pairwise comparisons between strains isolated from different depths of the same sea, which reveal a close association between atomic composition of the proteome and the availability nitrogen and phosphorus in the environment. The atomic composition of proteomes differs significantly among Prochlorococcus strains with different supplies of nitrogen in vivo; these different supplies result from different capacities for nitrogen assimilation. We repeated our whole-proteome analysis with the core proteomes of Prochlorococcus and obtained similar results. Our findings indicate that the elemental composition of proteomes is shaped by the availability of resources in the environment
[en] The determination of total sulfur in coal by the energy dispersive X-ray fluorescence analysis and its basic principle are introduced in this paper. The research focuses on the effect of matrix effect on measurement results, and the calibration model has been established. The test results show that the mean absolute error in determining the sulfur content in coal is 0.07%, the relative standard deviation is 1.80%, and single analysis needs only 200 s. (authors)
[en] Present article is devoted to geochemical characteristics of borosilicate ores of danburite of Ak-Arkhar Deposit. Geochemical characteristics of Ak-Arkhar Deposit of Tajikistan, including its chemical and mineralogical composition has been studied in detail.