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[en] Coal mining wastes are associated with serious environmental problems; they have potential as building materials, including alkali-activated cement. In this study, the effect of different coal mining wastes on the mechanical properties and microstructural development of alkali-activated materials (AAMs) was evaluated through XRD, SEM and FTIR spectroscopy. Different alkali-activated compounds were produced; the alkaline solution was composed of NaOH+Na2SiO3. The results obtained using the calcined coal sludge showed excellent mechanical performance, with compressive strength higher than 60 MPa. However, addition of metakaolin and ordinary Portland cement was necessary to increase the mechanical performance of calcined coal gangue materials. The formation of N-A-S-H gel and the incorporation of iron ions into the cementitious matrix were evidenced. Ultrasonic pulse velocity indicated the early polymerization during the reaction processes. The study verified that the different characteristics of the wastes influence the performance of alkali-activated materials.
[es]Los residuos de minería de carbón causan serios problemas ambientales, no obstante, tienen potencial como material de construcción, destacándose los cementos activados alcalinamente. El efecto de los residuos de carbón sobre las propiedades mecánicas y el desarrollo microestructural de los cementos activados alcalinamente son objeto de este estudio. Para ello, se utilizaron las técnicas de DRX, SEM y FTIR. Se produjeron diferentes compuestos activados alcalinamente, utilizando NaOH + Na2SiO3 como activador alcalino y curado térmico (50 °C durante 24 h). Los resultados obtenidos a partir del lodo de carbón calcinado mostraron un excelente rendimiento mecánico, con una resistencia a la compresión superior a 60 MPa. Sin embargo, en el caso de los materiales obtenidos a partir de la ganga de carbón calcinada, fue necesaria la adición de metacaolín y cemento Portland para aumentar sus resistencias mecánicas. Asimismo, se evidenció la formación de gel N-A-S-H y la incorporación de iones de hierro en la matriz cementante. El ensayo de velocidad de pulso ultrasónica indicó la polimerización inicial durante el proceso de reacción. Gracias a este se ha comprobado que las diferentes características de los residuos influyen en las propiedades y comportamiento de los correspondientes materiales activados alcalinamente.
[en] This study evaluated the effect of the application of liquid aerobic treated manure (continuous liquid composting, CLC) on physical, chemical and biological soil properties, with the objective of monitoring changes induced by soil management with CLC as a biofertilizer. Colonia, Uruguay (lat. 34,338164 S, long. 57,222630 W). Soil’s chemical properties, including nitrogen mineralization potential (NMP) and 15 microbiological properties (microbial biomass carbon, MBC; mesophylic aerobic bacteria; actinobacteria; filamentus fungi; fluorescein diacetate hydrolysis; dehydrogenase; with NMP; acid and alkaline phosphatase; cellulolose degraders; P-solubilizing bacteria; nitrifying; denitrifying and free-living N-fixing microorganisms; glomalin; and soil-pathogenicity index, SPI) were evaluated in two sites with similar cropping history, with one and three years of respective CLC application. CLC application had significant effects on soil microbial biomass (p<0.05), soil enzyme (p<0.1) and functional groups activity (p<0.05). SPI decreased in both sites with CLC application. No significant variations were detected for the chemical variables, with the exception of NMP, which was significantly high (p<0.05) in soil treated with CLC at both sites. The improved biological soil properties analyzed (MBC, soil enzyme activities and SPI, together with NMP) emerged as reasonable indicators to assess and monitor the effects of CLC application.
[en] The conference is dedicated to the very actual problem of nuclear energy production and chemical technology, which has been in the spotlight of the world scientific community for many years - radiation and chemical safety. It is hope that the result of this Conference will be an important stage in the history of science in the area of Radiation Chemical Safety.
[en] Starting from the Breit–Wigner model, we present a generalized approach for calculating the electrical conductance of a one-atom metallic constriction with electrochemical-potential control. In addition, the corresponding current intensity is determined. On the one hand, the nanoconstriction is conceived as a dilute (degenerate) Fermi gas (relatively low electron concentrations are considered) and, on the other hand, non-dilute gas is considered. Under these conditions, the Fermi energy-level into the Breit–Wigner formula is replaced by the corresponding chemical-potential energy. We emphasize the role of the optical potential as significant ingredient of the chemical potential.
[en] A steady magnetic field (SMF) was imposed during solidification of pure Mg. The effects of SMF on structure and bio-corrosion behavior of pure Mg were investigated. Results show that no detectable difference can be discerned with regard to the influence of SMF on the macrostructure of pure Mg. The (0002) basal plane replaced the () pyramidal plane as the primary plane with SMF treatment. The (0002) plane was further intensified with the increase of magnetic field intensity, while the relative intensity of the () plane became lower and lower. Immersion testing and electrochemical measurements have indicated that the beneficial effect of SMF treatment on the bio-corrosion resistance of pure Mg. The bio-corrosion resistance of pure Mg was further increased as magnetic field intensity increased. (paper)
[en] A re-usable in-situ-SQUID electrochemical cell for magnetisation studies during electrochemical cycling is presented. The proof of function is demonstrated by recording reversible magnetisation changes in LiFeO nanoparticles upon electrochemical cycling. The data imply the transition from inverse spinel structure (x=0) to a rocksalt phase (x=2). In addition, the setup is utilised to study the effect of lithiation on the Mott-Hubbard transition in VO.
[en] In this paper, CoxNi(1−x)(OH)2 with various molar ratios of Ni/Co is synthesized through chemical treatment. Effects of Ni/Co molar ratios on microstructure and property of CoxNi(1−x)(OH)2 are explored. It is found that electrochemical property of the Co–Ni hydroxides could be optimized for a Ni/Co molar ratio of 1. The obtained Co0.5Ni0.5(OH)2 exhibits the most hollow out structure and preferable electrochemical performance as electrode material in hybrid supercapacitor. The interconnected and porous architecture built by thin nanosheets of Co0.5Ni0.5(OH)2 facilitates ion diffusion and electron transportation. The experiment results further show that the property decay during charging/discharging may be caused by the collapse of structure.
[en] In this work, the combined effects of heat treatment and Sb addition on the discharge performance of Al-Sb alloys as anode for Al-air batteries have been evaluated experimentally. The results indicate that heat treatment decreases the electrochemical and discharge activities of Al-Sb alloys. Heat-treated Al-Sb alloys at 550 °C for 3 h show an improved anode performance. The Al-0.02Sb alloy exhibits a high discharge capacity and anodic efficiency of 2758 Ah kg−1 and 92.6%, respectively. Further prolonging the heat treatment time results in a decrease in anode performance. Microstructure characterization indicates that such negative effect is due to the higher-temperature and prolonged heat treatment to bring out significant grain growth and coarsening of Al-Sb precipitates. The corresponding corrosion behaviors are also discussed in detail.
[en] The behavior of an electrochemical integrator based on a solid electrolyte is studied in the galvanoharmonic charging mode. The possibility of applying simpler and more graphic calculation techniques and separating the impedance of electrochemical systems into active and reactive components is shown. The plotting of the dependences of the active and reactive impedance components on the ac frequency is used to determine the parameters of the studied equivalent electric cuircuits.
[en] Flexible and efficient fiber-shaped supercapacitors are being widely studied due to their enormous potential applications in portable electronics. Mesoporous CuCo2S4 nanosheets were prepared firstly on Ni wires (NW) with hydrothermal route and two same NW@CuCo2S4 electrodes were used to assemble a fiber-shaped all-solid-state symmetric supercapacitor. Electrochemical investigation demonstrated that as-fabricated device displayed good performances with high specific capacitance of 35.83 mF cm−2 at 1 mA cm−2 and high energy density of 7.2 µWh cm−2 at power density of 599.9 µW cm−2. In addition, the flexibility of the fiber-shaped supercapacitor was good and two devices in series can light up a red LED for more than 15 s. These results indicating its excellent comprehensive performance, which can meet the demand of practical applications in portable electronic devices.