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247 results on '"Wu, Zhongzhen"'

18. Exposure to Sublethal Concentrations of Dinotefuran Induces Apoptosis in the Gut of Diaphorina citriAdults via Activating the Mitochondrial Apoptotic Pathway

Author

Liu, Luyang, Yu, Xuanyue, Huang, Yuting, Liu, Cuiting, Xie, Xinyi, Wu, Zhongzhen, Lin, Jintian, and Shu, Benshui

Abstract

Diaphorina citriis a serious citrus pest. Dinotefuran is highly insecticidal against D. citri. To analyze the sublethal effects of dinotefuran on D. citriadults, an indoor toxicity test was performed, which revealed that the lethal concentration 50 (LC50) values were 4.23 and 0.50 μg/mL for 24 and 48 h treatments, respectively. RNA-Seq led to the identification of 71 and 231 differentially expressed genes (DEGs) after dinotefuran treatments with LC20and LC50doses, respectively. Many of the DEGs are significantly enriched in the apoptosis pathway. Dinotefuran-induced apoptosis in the gut cells was confirmed through independent assays of 4′,6-diamidino-2-phenylindole (DAPI) and TdT-mediated dUTP nick end labeling (TUNEL) staining. Increased levels of reactive oxygen species (ROS) and a loss of mitochondrial membrane potential were observed. Four caspase genes were identified, and dinotefuran treatments resulted in increased mRNA levels of DcCasp1and DcCasp3a. These findings shed light on the sublethal effects of dinotefuran on D. citri.

Published
2024
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41. NaF assisted preparation and the improved corrosion resistance of high content ZnO doped plasma electrolytic oxidation coating on AZ31B alloy

Author

Yang, Chao, Huang, Jian, Cui, Suihan, Fu, Ricky, Sheng, Liyuan, Xu, Daokui, Tian, Xiubo, Zheng, Yufeng, Chu, Paul K., Wu, Zhongzhen, Yang, Chao, Huang, Jian, Cui, Suihan, Fu, Ricky, Sheng, Liyuan, Xu, Daokui, Tian, Xiubo, Zheng, Yufeng, Chu, Paul K., and Wu, Zhongzhen

Abstract

In the present research, the NaF assisted plasma electrolytic oxidation (PEO) is designed to fabricate the high-content ZnO nanoparticles doped coating on AZ31B alloy. The microstructure, phase constituents and corrosion behavior of the PEO coatings are investigated systematically. The results reveal that the introduction of NaF promotes the formation of MgF2 nanophases in the passivation layer on Mg alloy, decreasing the breakdown voltage and discharge voltage. As a result, the continuous arcing caused by high discharge voltage is alleviated. With the increasing of NaF content, the Zn content in the PEO coating is enhanced and the pore size in the coating is decreased correspondingly. Due to the high-content ZnO doping, the PEO coating protected AZ31B alloy demonstrates the better corrosion resistance. Compared with the bare AZ31B alloy, the high-content ZnO doped PEO coated sample shows an increased corrosion potential from -1.465 V to -1.008 V, a decreased corrosion current density from 3.043×10-5 A·cm-2 to 3.960×10-8 A·cm-2 and an increased charge transfer resistance from 1.213×102 ohm·cm2 to 2.598×105 ohm·cm2. Besides, the high-content ZnO doped PEO coated sample also has the excellent corrosion resistance in salt solution, exhibiting no obvious corrosion after more than 2000 h neutral salt spraying and 28 days’ immersion testing. The improved corrosion resistance can be ascribed to the relative uniform distribution of ZnO in PEO coating which can transform to Zn(OH)2 and form a continuous protective layer along the corrosion interface. © 2023

Published
2023

42. Characteristics of continuous high power magnetron sputtering (C-HPMS) in reactive O2/Ar atmospheres.

Author

Cui, Suihan, Liu, Liangliang, Jin, Zheng, Zhou, Lin, Ruan, Qingdong, Wu, Zhongcan, Fu, Ricky K. Y., Tian, Xiubo, Chu, Paul K., and Wu, Zhongzhen

Subjects
MAGNETRON sputtering, REACTIVE sputtering, THIN films, PLASMA flow, PARTIAL pressure, OXYGEN
Abstract

Target poisoning is prevalent in reactive magnetron sputtering and causes deleterious effects, especially in deposition using metal targets. Both the deposition rate and the stoichiometry ratio of the coatings will be compromised because of the quicker coverage of the poisoning materials on the target relative to removal by sputtering. Continuous high-power magnetron sputtering (C-HPMS) possesses merits such as more rapid sputtering than high-power impulse magnetron sputtering and better target poisoning resistance. In this work, the discharge and plasma characteristics of C-HPMS for an Al metal target in reactive O2/Ar atmospheres are investigated by modeling and alumina deposition. At a constant oxygen partial pressure, larger discharge power increases target etching significantly compared to surface combination with O2, leading to reduced surface poisoning. Besides, a higher temperature is produced near the target to produce more intense rarefaction effects and decrease the risk of target poisoning. In Al discharge, the stable deposition window in the O2/Ar ratio under 120 W/cm2 is 5 times of that under 20 W/cm2. Moreover, a large deposition rate of 112 nm/min is achieved at the poisoning-saturated point and a target/substrate distance can be increased to larger than 40 cm, thus providing more flexibility in the design of deposition parameters and hardware requirement. Our results show that high discharge intensity improves plasma density and ionization rates of reactive particles boding well for the deposition of under-stoichiometric and higher-quality amorphous Al2O3 films. The reactive C-HPMS technique has large potential in the commercial production of functional coatings and thin films. [ABSTRACT FROM AUTHOR]

Published
2021
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45. Influence of layer number on microstructure, mechanical properties and wear behavior of the TiN/Ti multilayer coatings fabricated by high-power magnetron sputtering deposition

Author

Yueming Li, Yinan Xiao, Wu Zhongzhen, Liyuan Sheng, Beining Du, Cheng Jiao, and Longquan Shao

Subjects
Materials science, Strategy and Management, Titanium alloy, chemistry.chemical_element, Management Science and Operations Research, Sputter deposition, engineering.material, Microstructure, Industrial and Manufacturing Engineering, Coating, chemistry, Sputtering, engineering, Composite material, Tin, Elastic modulus, Layer (electronics)
Abstract

In the present research, the TiN/Ti multilayer coatings with different layers were fabricated on Ti6Al4V substrates with same deposition time by high-power DC reactive magnetron sputtering. Their microstructure, phase constituent, mechanical properties and wear behavior were studied to explore the influence of the layer number. The results reveal that increasing of layer number in TiN/Ti multilayer coatings refines the grains and promotes the transformation of the crystal orientation preference of the TiN layer from (111)TiN to a mixture of (111)TiN, (200)TiN and (220)TiN. Moreover, the thickness of the TiN/Ti multilayer coating increases with the increased layer number. The Ti interlayer and TiN layer have a sinuous interface at the atomic scale with many dislocations, and no orientation relationship between these layers is found. With the increasing of layer number, the elastic modulus and hardness of the TiN/Ti multilayer coatings increase firstly and then decrease. The two-layer and four-layer TiN/Ti multilayer coatings obtain the maximum elastic modulus and hardness, respectively. Moreover, the increased layer number improves the adhesion of the TiN/Ti multilayer coating obviously, and the twelve-layer TiN/Ti multilayer coating obtains the highest adhesion, which could be ascribed to the relaxation of interfacial stress. The increased Ti interlayers promote the diversification of the friction coefficient of the TiN/Ti multilayer coatings. With the proceeding of wear test, the friction coefficients of the one-layer and two-layer TiN/Ti multilayer coatings maintain an increasing tendency, but the friction coefficients of the four-layer, eight-layer and twelve-layer TiN/Ti multilayer coatings drop at final, middle and initial stage, respectively. The one-layer, two-layer and four-layer TiN/Ti multilayer coatings have similar wear rates which are less than one twentieth of the wear rate of the Ti6Al4V substrate. While the wear rates of the eight-layer and twelve-layer TiN/Ti multilayer coatings are higher than that of the Ti6Al4V substrate.

Published
2021

47. Nano-second temporal particle behavior in high-power impulse magnetron sputtering discharge in a cylindrical cathode.

Author

Cui, Suihan, Wu, Zhongzhen, Xiao, Shu, Zheng, Bocong, Chen, Lei, Li, Tijun, Fu, Ricky K. Y., Chu, Paul K., Tian, Xiubo, Tan, Wenchang, Fang, Daining, and Pan, Feng

Subjects
*TIME-resolved spectroscopy, *CATHODES, *MAGNETRON sputtering, *PARTICLES, *HIGH voltages, *PLASMA flow, *ELECTROHYDRAULIC effect
Abstract

Systematic analysis of discharge processes is needed for a good understanding of the physical mechanism that enables optimal coating deposition, especially pulsed discharges sustained by high voltages and large currents. Owing to the temporal and complex characteristics of the discharge process and relatively simplistic analytical methods, the discharge process and particle evolution in high-power impulse magnetron sputtering (HiPIMS) are still not well understood. In this work, a cylindrical cathode is introduced to restrict the discharge and delay plasma loss, and a global model is established to simulate the discharge on a Cr target in N2/Ar. Particles with different reaction energies appearing successively produce an asynchronous discharge phenomenon, and a series of inflection points corresponding to different physical processes including excitation, sputtering, ionization, and diffusion are observed from the particle density evolution curves. High-precision and time-resolved spectrometry (400 ns) is utilized to monitor the evolution of particles with time, and inflection points predicted by the model are observed experimentally to verify the particle behavior in the HiPIMS discharge. [ABSTRACT FROM AUTHOR]

Published
2020
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48. The Corrosion Behavior of Al/Al 2 O 3 Composite Films with Ultra-Dense Structure Exposed to Lead-Bismuth Eutectic at 450 to 650 °C.

Author

Yin, Xing, Li, Xiteng, Wang, Hao, Zhao, Ke, Wang, Jun, Chen, Le, Wu, Zhongzhen, and Chen, Yong

Subjects
ALUMINUM oxide, BISMUTH, EUTECTICS, PHASE transitions, CERAMIC coating, CHEMICAL reactions, MAGNETRON sputtering, PITTING corrosion
Abstract

Al2O3 coatings are the most promising candidate material for mitigating (lead-bismuth eutectic) LBE corrosion at elevated temperatures, but preventing inward diffusion of Pb, Bi, and O for the ceramic coating remains a critical challenge. Here, we have fabricated an amorphous Al2O3 coating with an ultra-dense structure by continuous high-power magnetron sputtering (C-HPMS). After LBE corrosion at 550 °C for 2000 h, nanocavities induced by the phase transformation from amorphous to γ-Al2O3 provide the diffusion path for Fe, O, Pb, and Bi in which the corrosion products, such as Fe3O4, PbO2, or their mixed oxides, form. Furthermore, the diffusion of Pb to the substrate and Cr segregation at the interface between the coating and substrate are observed for the sample exposed to LBE at 550 °C for 4000 h. Additionally, the hardness and interface bonding strength are enhanced after LBE corrosion. Moreover, pit corrosion was found to be the main failure mode of coating, and pits that merged with each other induced large area failure at a temperature of 650 °C. The corrosion mechanism of Al2O3 includes element diffusion, phase transformation, and chemical reaction. This work not only provides a deep understanding of the corrosion mechanism of amorphous Al2O3 coatings, but also shows the optimization method on the corrosion resistance of Al2O3 coating. [ABSTRACT FROM AUTHOR]

Published
2023
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49. High-precision modeling of dynamic etching in high-power magnetron sputtering

Author

Cui, Suihan, primary, Chen, Qiuhao, additional, Guo, Yuxiang, additional, Chen, Lei, additional, Jin, Zheng, additional, Li, Xiteng, additional, Yang, Chao, additional, Wu, Zhongcan, additional, Su, Xiongyu, additional, Ma, Zhengyong, additional, Fu, Ricky K Y., additional, Tian, Xiubo, additional, Chu, Paul K, additional, and Wu, Zhongzhen, additional

Published
2022
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