Chongqing University of Technology

About: Chongqing University of Technology is a education organization based out in Chongqing, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 5199 authors who have published 4205 publications receiving 35954 citations. The organization is also known as: Chongqing Institute of Technology.

Correlation of microstructural, textural characteristics and hardness of Ti–6Al–4V sheet β-cooled at different rates

Abstract: In this work, a hot-rolled Ti–6Al–4V (Ti-64) sheet was annealed at 1050 °C (β field) and then subjected to different coolings (in water, air and furnace). Electron backscatter diffraction, electron channeling contrast imaging, energy-dispersive spectroscopy and X-ray diffraction techniques were jointly utilized to comprehensively reveal microstructural and textural characteristics of the specimens following various β-cooling rates. Hardness measurements were also performed to probe the hardness variation associated with the β-cooling rates and were further rationalized based on the revealed microstructures. Results show that the β-cooled specimens in water, air and furnace exhibited twinned martensite, basket-weave and parallel-plate Widmanstatten structures, respectively. The Burgers orientation relationship is always obeyed during the β → α transformation at all cooling rates. After phase transformation, major α texture components ((0°, 60°, 0°), (90°, 30°, 30°) and (90°, 90°, 30°)) are completely different from those of the as-received material ((0°, 90°, 0°) and (90°, 30°, 0°)). Slow cooling facilitates preferable nucleation of α phases at prior β boundaries and strengthens α-variant selection, leading to greatly intensified transformation texture (the maximum density from 9.5 to 31.1 times of random). Hardness values of the β-cooled specimens drop from 416.8 ± 4.3 HV for water cooling to 329.2 ± 23.6 HV for furnace cooling. Quantitative calculations suggest such hardness variation can be more related to differences in grain size between them, as compared to specific contributions from other microstructural and textural characteristics.

Fuzzy rough set models over two universes

Abstract: The extension of rough set model is an important research direction in rough set theory. The aim of this paper is to present new extensions of the rough set model over two different universes which are rough fuzzy set model in a generalized approximation space, rough set model in a fuzzy approximation space and rough fuzzy set model in a fuzzy approximation space based over two different universes. Moreover, the properties of the approximation operators in these models are investigated. Furthermore, by employing cut set of fuzzy set and fuzzy relation, classical representations of fuzzy rough approximation operators are studied. Finally, the measures of fuzzy rough set models are presented, and the relationships among the fuzzy rough models and rough set model over two universes are investigated.

Design, synthesis and biological evaluation of novel Schiff base-bridged tetrahydroprotoberberine triazoles as a new type of potential antimicrobial agents

Abstract: A series of novel Schiff base-bridged tetrahydroprotoberberine (THPB) triazoles were designed, synthesized and characterized for the first time. Antimicrobial assay showed that some of the prepared compounds exerted stronger antibacterial and antifungal activities than the reference drugs. Especially, THPB triazole 7a gave low MIC values of 0.5, 1 and 2 μg mL−1 against B. yeast, M. luteus and MRSA, respectively. Further experiments indicated that the highly active molecule 7a was able to rapidly kill the MRSA strain and did not trigger the development of bacterial resistance even after 14 passages. The preliminary exploration for the antimicrobial mechanism revealed that compound 7a could effectively intercalate into calf thymus DNA to form a 7a–DNA supramolecular complex, and its Zn2+ complex had the ability to directly cleave pUC19 DNA, which suggested that compound 7a might be a potentially dual-targeting antibacterial molecule. It was also found that compound 7a could be efficiently stored and carried by human serum albumin (HSA), and the hydrophobic interactions and hydrogen bonds played important roles in the transportation of HSA to the active molecule 7a.

Comparison about effects of Ce, Sn and Gd additions on as-cast microstructure and mechanical properties of Mg–3.8Zn–2.2Ca (wt%) magnesium alloy

Abstract: In this paper, the effects of Ce, Sn and Gd additions on the as-cast microstructure and mechanical properties of Mg–3.8Zn–2.2Ca (wt%) magnesium alloy are investigated and compared. The results indicate that adding 1.0 wt% Ce, 1.0 wt% Sn or 1.0 wt% Gd can effectively refine the grains of the Mg–3.8Zn–2.2Ca alloy, and the refinement efficiency of Ce addition is relatively high, followed by the additions of Sn and Gd, respectively. Accordingly, the tensile properties of the as-cast Mg–3.8Zn–2.2Ca alloy are improved by the additions of Ce, Sn or Gd, with the improvement resulting from the Ce addition being best and followed by the additions of Sn and Gd, respectively. In addition, adding 1.0 wt% Ce, 1.0 wt% Sn or 1.0 wt% Gd to the Mg–3.8Zn–2.2Ca alloy can also improve the creep properties of the as-cast alloy. Among the Ce-, Sn- and Gd-containing alloys, the creep properties of the Sn- and Gd-containing alloys are similar but lower than that of the Ce-containing alloy.