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Published By American Scientific Publishers

2158-5857, 2158-5849

2021 ◽  
Vol 11 (12) ◽  
pp. 2033-2038
Author(s):  
Kaiju Shi ◽  
Chengxin Wang ◽  
Rui Li ◽  
Shangda Qu ◽  
Zonghao Wu ◽  
...  

Two multiple quantum well (MQW) InGaN/GaN structures emitting green light, without (A) and with (B) an indium (In) volatilization suppression technique (IVST) during growth of the active region, were fabricated. The dependencies of the photoluminescence (PL) spectra upon temperature at different levels of excitation power were investigated. The results indicate that an IVST can increase the In content while suppressing the phase separation caused by volatilization of that In incorporated in the well layers. Also, compared with Structure B with IVST, which contains one phase structure, Structure A without IVST, which contains two separate phases (i.e., an In-rich phase and an In-poor phase), exhibits higher internal quantum efficiency (IQE) at low excitation power and lower IQE at high excitation power. The former is mainly attributed to the stronger In-rich phase-related localization effect of Structure A, because the In-rich phase-related emission dominates the PL spectra of Structure A at a low excitation power; the latter is mainly due to the In-poor phase-related weaker localization effect of Structure A, because the In-poor phase-related emission dominates the PL spectra of Structure A at high excitation power because localized states in this In-rich phase are saturated.


2021 ◽  
Vol 11 (12) ◽  
pp. 1988-1996
Author(s):  
Cao Zhi-Kang ◽  
Li Ji-Dong ◽  
Li Zhen ◽  
Wang Xue-Lian ◽  
Yue Ling-Feng

Lithium cobaltate as a cathode material has great recycling value in the recycling process of spent lithium-ion batteries, To promote the thermal reduction process of lithium cobaltate and recover high-value cobalt and lithium metals, we studied the process of lithium cobaltate reduction by carbon under different conditions and its thermal reaction kinetics. The effects of calcination temperature, raw material ratio, pelletizing pressure and holding time on the reduction rate of lithium cobaltate were investigated by controlling variables. The results showed that the optimum experimental conditions were as follows: mass ratio of carbon and lithium cobaltate was 1:1, pelletizing pressure was 45 MPa, calcination temperature was 800 °C, and calcination time was 6 h. Under these conditions, lithium cobaltate could be converted into cobalt and lithium carbonate, and the recovery rate of cobalt and lithium was 97% and 95%, respectively. A kinetic study on the carbothermal reduction reaction of LiCoO2 showed that the average activation energy of the carbothermal reaction of LiCoO2 under nitrogen protection was 280.6851 kJ/mol, and the mechanism model of the thermal decomposition reaction of LiCoO2 was controlled by chemicals, showing a deceleration curve. The corresponding process conforms to the threedimensional diffusion mechanism of the inverse Jander equation, which lays a theoretical foundation for the high-efficiency separation and recovery of LiCoO2 cathode material for waste lithium-ion batteries.


2021 ◽  
Vol 11 (12) ◽  
pp. 2004-2009
Author(s):  
Ruomei Wu ◽  
Shuai Wu ◽  
Haiyun Jiang ◽  
Zigong Chang ◽  
Zhiqing Yuan ◽  
...  

Anti-corrosion of aluminum alloys with different roughness were researched in this study. To further verify the relationship between anti-corrosion and surface roughness, surface with micro structure alloy was successfully fabricated via anode oxidation on aluminum. The water contact angle of aluminum alloy surface after coating polypropylene film was 154° and sliding angle was 3°. The micro-nano structure was constructed by adding nano-SiO2. The contacts angle of surface was 165° and the sliding angle was 1.8°. The superhydrophobic samples were used to test corrosion resistance. Compared with aluminum coated with unmodified film, the corrosion potential for modified superhydrophobic aluminum alloy increased by about 0.05 V. When nano-SiO2 particles were added, the corrosion resistance for the sample was also improved.


2021 ◽  
Vol 11 (12) ◽  
pp. 2047-2051
Author(s):  
Ruimin Fu ◽  
Hong Zhang ◽  
Wei Tang ◽  
Xue Yang ◽  
Ding Wang ◽  
...  

This study investigate the inhibiting effect of fengycin on respiration and nutrient utilization of Penicillium expansum. The respiratory inhibition rate of the P. expansum was determined by the test of dissolved oxygen fengycin, The effect of fengycin treatment on the activity of P. expansum mitochondrial complex enzyme was detected by mitochondrial enzyme activity assay. The ability of fengycin treatment to P. expansum the utilization of total sugar and total protein was determined by DNS colorimetric method and biuret method. After fengycin treatments, the TCA pathway of respiratory metabolism in P. expansum was inhibited. Besides, fengycin could block the gene expression in P. expansum by binding P. expansum mitochondrial complex enzyme II and III related genes. Therefore, the activity of mitochondrial enzymes was affected. With the increasement of fengycin concentration, the absorption and utilization capacity of P. expansum to total sugar and total protein decreased significantly. Fengycin could inhibit the respiratory metabolism and reduce the biochemical metabolism level in P. expansum and finally caused the growth inhibition.


2021 ◽  
Vol 11 (12) ◽  
pp. 2015-2023
Author(s):  
Zhaohui Han ◽  
Yang Xu ◽  
Lei Xu ◽  
Shenghui Guo

In this research, the diamond particles were coated with titanium by microwave heating method, then the Ti-coated diamond particles were used as raw material to fabricate the diamond/Al composites by microwave sintering. The result shows that the diamond particles could be covered with a uniform and continuous Ti coating under microwave irradiation, and the best Ti coating was obtained at 810 °C for 1 h. The metallic bond between diamond and Ti was formed to generate the intermediate transition layer of TiC. The diamond/Al composites which used Ti-coated diamond particles as raw material and were fabricated by microwave sintering show high relative density and hardness. The relative density and hardness of the diamond/Al composites increased with the temperature. While the composites were sintered at 710 °C for 1 h, the density could reach 2.855 g·cm−3, and relative density was 92.09%, which shows better microstructures and properties. There is Al3Ti alloy phase in Ti-coated diamond/Al composites, so the Ti-coated diamond can be well combined with the Al matrix, which can further improve the properties of the composites.


2021 ◽  
Vol 11 (12) ◽  
pp. 1901-1925
Author(s):  
Shuai Li ◽  
Chengsong Zhang ◽  
Jiping Lu ◽  
Ruiduo Chen ◽  
Dazhi Chen ◽  
...  

High nitrogen austenitic stainless steels are commonly used in wide range of applications because of their excellent properties, attracting super attention over the past decades. Compared with other metal materials, high nitrogen austenitic stainless steel increases the nitrogen content under the premise that the structure is austenite, giving it excellent mechanical properties and corrosion resistance. Based on relevant documents from the past ten years, this article summarizes and compares three preparation methods for high nitrogen austenitic stainless steels, namely: powder nitriding, melt nitriding and bulk nitriding. They can be divided into six categories according to other differences as explained by the latest research progress on strengthening and toughening mechanism for high nitrogen austenitic stainless steels: composite structure strengthening, fine grain strengthening, precipitation strengthening and strain strengthening. This article also reviews the research progress on excellent properties of high nitrogen stainless steel, including strength, hardness and corrosion resistance. It further describes the emerging nickel-free high nitrogen austenitic stainless steels and its biocompatibility. Welding applications of high nitrogen austenitic stainless steels are also described from three aspects: friction stir welding, arc welding and brass solder. Finally, this article puts forward the development direction of high nitrogen austenitic stainless steels in the future.


2021 ◽  
Vol 11 (12) ◽  
pp. 1958-1965
Author(s):  
Debashruti Bhattacharya ◽  
Vinay Kumar ◽  
Gopinath Packirisamy

The present study reports the green synthesis of carbon dots (C-dots) by one-step, facile hydrothermal process, using red onion peels as the base material. The optical properties of the C-dots have been studied in detail using UV-Visible spectroscopy, fluorescence spectroscopy, and quantum yield measurements. The structural and compositional analysis of fluorescent C-dots was done via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Surface chemistry of the C-dots was studied using Fourier transform infrared spectroscopy (FTIR). The stability measurement of C-dots was done via Zeta potential. The biocompatibility of the C-dots was evaluated using a breast cancer cell line (MCF-7). C-dots were used as potential bioimaging agents for fluorescence imaging of mammalian cell lines. Concentration-dependent cellular uptake of the C-dots by the MCF-7 cells was shown qualitatively using fluorescence microscopy. The study also assessed the antioxidant activity of the C-dots. Thus, this work validates the red onion peel-derived C-dots as excellent bioimaging and antioxidant agents for mammalian cell lines.


2021 ◽  
Vol 11 (12) ◽  
pp. 2039-2046
Author(s):  
Yu Zhang ◽  
Ruijian Song ◽  
Xiang Zhang

Alloying as a way of improving material properties has really gained a lot of global attention over the past few years. Alloying majorly improves physicochemical, electrochemical, thermal, and mechanical and corrosion resistance of a parent material. In this work, electrodeposition using a sulphamate electrolytic cell under varied concentrations of the secondary phase of cobalt. Characterization of the alloy was achieved using scanning electron microscopy (SEM), optical microscopy (OM), and X-ray diffraction (XRD) techniques. Corrosion resistance was investigated using potentiometric and impedance tests, reported, and well explained.


2021 ◽  
Vol 11 (12) ◽  
pp. 1942-1950
Author(s):  
Maojie Cheng ◽  
Dongcheng Gu ◽  
Jurui Feng ◽  
Caixia Li

To investigate the effect of hsa-miR-203a-3p overexpression on the proliferation of human skin squamous cell carcinoma (CSCC) cells and its possible mechanism. Real-time PCR (RT-PCR) was used to detect the expression of miR-203a-3p in cell lines and clinical human CSCC samples. A luciferase reporter system was used to verify the targeted regulatory relationship of miR-203a-3p to APC, and a miR-203a-3p lentivirus overexpression vector was constructed and used to transfect CSCC SCL-1 cells. RT-PCR was used to detect changes in miR-203a-3p and APC gene expression and Western blot was used to detect differences in APC and β-catenin protein expression. MTT and clonogenic assays were used to evaluate cell growth and detect clone formation, respectively. MiR-203a-3p showed decreased expression in SCL-1 cells and CSCC samples. Results of luciferase reporter assay showed that the ratio of Renilla luciferase to Firefly luciferase was significantly decreased in SCL-1 cells of the APC 3′-UTR+miR-203a-3p (wild-type) group compared with those of the APC 3′-UTR+negative control group. After lentiviral infection of SCL-1 cells, the abundance of miR-203a-3p and phosphorylated β-catenin protein was significantly increased, whereas the abundance of APC and β-catenin protein was significantly reduced. Cell phenotyping analysis showed that miR-203a-3p decreased cell proliferation. MiR-203a-3p inhibits the proliferation of SCL-1 cells through targeted regulation of APC and may play a role as a tumor suppressor gene through the Wnt pathway. Nanotechnology has potential future research applications in gene vector transfection technology.


2021 ◽  
Vol 11 (12) ◽  
pp. 1935-1941
Author(s):  
Ming Wang

Radiotherapy (RT), as an essential method for glioma treatment, can effectively kill tumor cells. However, radiation resistance of blood–brain barrier and glioma cells leads to poor efficacy of RT, which cannot effectively improve the survival time of patients. Therefore, designing methods to improve the sensitivity of glioma cells to radiation is the key to improve the effect of RT. We propose a novel strategy for radiosensitizing glioma cells based on gold nanoparticles coated with polyethylene glycol. Results of clone formation experiments demonstrated that the Au NPs@PEG radiosensitization ratio (SER) was as high as 1.74, which effectively improved the killing effect of X-rays on the tumor. We successfully established a glioma mouse model and applied Au NPs@PEG to RT. Results of in vivo experiments showed that Au NPs@PEG combined with X-rays can significantly reduce the expression of tumor-related molecules and effectively inhibit the process of tumor invasion, proliferation, and migration.


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