Investigation into secondary phases in steels microalloyed with vanadium and nitrogen

In the present work two nitrogen and vanadium microalloyed steels were compared in terms of the nitride or carbonitride phases present. The thermal evolved gas analysis clearly showed that one of the steels contains a higher volume fraction of nitrogen bound as vanadium carbonitride than the other steel in a natural relation to the total nitrogen content in steels. For the promotion of this statement, the content of free nitrogen with the use of the hot hydrogen extraction method was analysed and the thermodynamic prediction of the equilibrium composition of precipitating phases in microalloyed steels by the CALPHAD method with the use of the Thermo-Calc software was carried out

STBU system for the NIST 2006 speaker recognition evaluation

This paper describes STBU 2006 speaker recognition system, which performed well in the NIST 2006 speaker recognition evaluation. STBU is consortium of 4 partners: Spescom Data Voice (South Africa), TNO (Netherlands), BUT (Czech Republic) and University of Stellenbosch (South Africa). The primary system is a combination of three main kinds of systems: (1) GMM, with short-time MFCC or PLP features, (2) GMM-SVM, using GMM mean supervectors as input and (3) MLLR-SVM, using MLLR speaker adaptation coefficients derived from English LVCSR system. In this paper, we describe these sub-systems and present results for each system alone and in combination on the NIST Speaker Recognition Evaluation (SRE) 2006 development and evaluation data sets. © 2007 IEEE

Effect of Ag modification on TiO2 and melem/g-C3N4 composite on photocatalytic performances

Abstract Here, the comparison of two different semiconductor materials is demonstrated, TiO2 and melem/g-C3N4 composites—modified with balls of approximately 5 nm Ag nanoparticles (NPs) as photocatalysts for the degradation of the model dye acid orange 7 (AO7). The melem molecule synthesized here is one of a series of organic compounds consisting of triazine ring compounds with a structure similar to that of melam and melamine. The photodegradation process of AO7 was carried out to examine all powder materials as a potential photocatalyst. Additionally, two different lamps of wavelengths 368 nm (UV light) and 420 nm (VIS light) were applied to compare the photodegradation tests. A new synthesis route for the acquisition of Ag NPs (Ag content 0.5, 1.0 and 2.5 wt%), based on a wet and low temperature method without the use of reducing reagents was proposed. The best photocatalytic performances under UV and VIS light were obtained for both, TiO2 and melem/g-C3N4 materials (new synthesis route) modified with a very low Ag content—0.5 wt%. The photodegradation activities using UV lamp (3 h, 368 nm irradiation) for samples with 0.5 wt% of Ag: TiO2 and melem/g-C3N4, in excess of 95 and 94%, respectively, were achieved. The highest photoactive materials melem/g-C3N4 with 0.5 and 1 wt% Ag revealed 98% of activity under the VIS lamp after 3 h long irradiation. Our work demonstrates a novel, environmentally acceptable, and cost-effective chemical strategy for preparation of photocatalysts suitable for degradation of organic contaminants in wastewater treatment

Optimizing the monomer structure of polyhedral oligomeric silsesquioxane for ion transport in hybrid organic–inorganic block copolymers

Poly(ethylene oxide)-b-polyhedral oligomeric silsesquioxane (PEO–POSS) mixed with lithium bis(trifluoromethanesulfonyl)imide salt is a nanostructured hybrid organic–inorganic block copolymer electrolyte that may enable lithium metal batteries. The synthesis and characteristics of three PEO–POSS block copolymer electrolytes which only differ by their POSS silica cage substituents (ethyl, isobutyl, and isooctyl) is reported. Changing the POSS monomer structure results in differences in both thermodynamics and ion transport. All three neat polymers exhibit lamellar morphologies. Adding salt results in the formation of a disordered window which closes and gives way to lamellae at higher salt concentrations. The width of disordered window decreases with increasing length of the POSS alkyl chain substituent from ethyl to isobutyl and is absent in the isooctyl sample. Rheological measurements demonstrate good mechanical rigidity when compared with similar all-organic block copolymers. While salt diffusion coefficient and current ratio are unaffected by substituent length, ionic conductivity increases as the length of the alkyl chain substituent decreases: the ethyl substituent is optimal for ion transport. This is surprising because conventional wisdom suggests that ion transport occurs primarily in the PEO-rich domains, that is, ion transport should be unaffected by substituent length after accounting for the minor change in conducting phase volume fraction. © 2020 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2020 © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 363–371