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Jun Zhao,Shan-Ming Luo,Feng-Qiang Li,Chen-Bing Xu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.
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Study on Rolling Process Analysis and Experiment of Small Cone Angle Spiral Bevel Gear
Jun Zhao,Jin-Huo Wang,Feng-Qing Li,Dong-Hao Li 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.7
Gear rolling process is a continuous rolling process by rotating and radial feeding motion of rolling wheel. It has advantages of low manufacturing cost, high gear strength and low forming load. The rolling processes of extrusion forming, gear splitting, continuous rolling and reshaping were analyzed by finite element method. The kinematic relationship between the rolling wheel and the forming gear during rolling deformation was studied. The results showed that the meshing motion between the rolling wheel and the billet could be guaranteed when the initial extrusion of the billet was not less than 1 mm. At the rolling gear splitting stage, the equivalent strain of the billet was shown to be related to the deformation of the material, which attained the largest at the root of the tooth. However, the equivalent stress of the billet was found to be dependent on the contact position of the rolling wheel, which has the maximum value at the root of the tooth in the contact area. During the continuous rolling forming stage, the forming load varied regularly and increased continuously with the rolling feed. The tooth profile of the gear was complete after the rolling reshaping process. According to the analysis and calculation results, the structure of rolling forming device was designed. Experiments showed that spiral bevel gears were able to be formed by rolling, and the billet size had an effect on the rolling process. When the size of billet was about 2 mm larger than the dividing circle radius of target gear, the quality of rolled gear was better. The results have important guiding significance for further research rules of rolling forming processes.
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Jun Liang Zhao,Xiao Wei Sun,Hyukhyun Ryu,Swee Tiam Tan IEEE 2011 IEEE transactions on electron devices Vol.58 No.5
<P>A Sn-doped Ga<SUB>2</SUB>O<SUB>3</SUB> thin film was deposited on a n<SUP>+</SUP>-Si substrate by metal-organic chemical vapor deposition. The Ga<SUB>2</SUB>O<SUB>3</SUB> film was found to be amorphous-like and exhibited n-type conduction with Sn doping. Room-temperature electroluminescence was clearly observed from the Sn:Ga<SUB>2</SUB>O<SUB>3</SUB>/n<SUP>+</SUP> -Si diode, including an ultraviolet (UV) emission at ~ 370 nm, a yellow emission at ~ 580 nm, and a red emission at ~ 680 nm. The UV emission is assigned to the transition from Sn<SUB>Ga</SUB> donor to the <I>V</I><SUB>Ga</SUB> acceptor, whereas the visible emissions were assigned to be related to the dangling bond defects.</P>
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Zhao, Xueyan,Yang, Qiang,Zhao, Kewei,Jiang, Chao,Ren, Dongren,Xu, Pan,He, Xiaofang,Liao, Rongrong,Jiang, Kai,Ma, Junwu,Xiao, Shijun,Ren, Jun,Xing, Yuyun Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.7
In the last few decades, transgenic animal technology has witnessed an increasingly wide application in animal breeding. Reproductive traits are economically important to the pig industry. It has been shown that the bone morphogenetic protein receptor type IB (BMPR1B) A746G polymorphism is responsible for the fertility in sheep. However, this causal mutation exits exclusively in sheep and goat. In this study, we attempted to create transgenic pigs by introducing this mutation with the aim to improve reproductive traits in pigs. We successfully constructed a vector containing porcine BMPR1B coding sequence (CDS) with the mutant G allele of A746G mutation. In total, we obtained 24 cloned male piglets using handmade cloning (HMC) technique, and 12 individuals survived till maturation. A set of polymerase chain reactions indicated that 11 of 12 matured boars were transgene-positive individuals, and that the transgenic vector was most likely disrupted during cloning. Of 11 positive pigs, one (No. 11) lost a part of the terminator region but had the intact promoter and the CDS regions. cDNA sequencing showed that the introduced allele (746G) was expressed in multiple tissues of transgene-positive offspring of No.11. Western blot analysis revealed that BMPR1B protein expression in multiple tissues of transgene-positive $F_1$ piglets was 0.5 to 2-fold higher than that in the transgene-negative siblings. The No. 11 boar showed normal litter size performance as normal pigs from the same breed. Transgene-positive $F_1$ boars produced by No. 11 had higher semen volume, sperm concentration and total sperm per ejaculate than the negative siblings, although the differences did not reached statistical significance. Transgene-positive $F_1$ sows had similar litter size performance to the negative siblings, and more data are needed to adequately assess the litter size performance. In conclusion, we obtained 24 cloned transgenic pigs with the modified porcine BMPR1B CDS using HMC. cDNA sequencing and western blot indicated that the exogenous BMPR1B CDS was successfully expressed in host pigs. The transgenic pigs showed normal litter size performance. However, no significant differences in litter size were found between transgene-positive and negative sows. Our study provides new insight into producing cloned transgenic livestock related to reproductive traits.
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Influence of Li Addition on the Microstructures and Mechanical Properties of Mg–Li Alloys
Jun Zhao,Jie Fu,Bin Jiang,Aitao Tang,Haoran Sheng,Tianhao Yang,Guangsheng Huang,Dingfei Zhang,Fusheng Pan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
In this study, Mg-xLi (x = 0, 1, 2, 3 and 5 wt%) alloys have been extruded to examine the role of Li content on microstructuresand tensile properties. The results revealed that Li addition increased the grain size and led to the formation of the transversedirection (TD)-split texture. These were mainly attributed to the promoted DRX process and the increased activity of prismatic⟨a⟩ slip during extrusion. Tensile tests revealed that the elongation of Mg-5Li sheet reached ~ 22.4% along the ED. Moreover, it exhibited a higher elongation of ~ 27.3%, three times than pure Mg, along the TD. During tension along the ED,with increasing Li content, more prismatic ⟨a⟩ slip and preferable intergranular strain coordination ability to accommodatethe plastic strain, leading to the enhanced room-temperature ductility. In contrast, more basal ⟨a⟩ slips and extension twinswere also activated along the TD, which further contributed to the enhanced ductility. Therefore, the ductility of Mg sheetsat room temperature gradually improved with Li addition due to the combining effects of basal ⟨a⟩ slip, prismatic ⟨a⟩ slip,extension twin and preferable intergranular strain coordination ability.
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Jun-Quan Zhao,Guo-Zhen Du,You-Cai Xiong,Yi-Fu Wen,Monika Bhadauria,Satendra Kumar Nirala 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.12
We determined a minimum effective dose of gallic acid (3,4,5-trihydroxy benzoic acid; 50 mg/ kg, i.p.) and piperine (10 mg/kg, p.o.) through their therapeutic potential and further evaluated them individually and in combination against beryllium-induced biochemical alterations and oxidative stress consequences in female albino rats. The administration of beryllium altered blood biochemical variables by significantly depleting hemoglobin, albumin and urea, whereas it enhanced bilirubin and creatinine. The release of serum transaminase, lactate dehydrogenase and γ-glutamyl transpeptidase was significantly greater, and was concomitant with a decrease in serum alkaline phosphatase. A significant increase in lipid peroxidation and a decrease in glutathione, superoxide dismutase and catalase in the liver and kidney was an indication of oxidative stress due to beryllium exposure. Individual administration of gallic acid and piperine moderately reversed the altered biochemical variables, whereas the combination of these was found to completely reverse the beryllium-induced biochemical alterations and oxidative stress consequences. We concluded that gallic acid exerts a synergistic effect when administered with piperine and provides a more pronounced therapeutic potential in reducing beryllium-induced hepatorenal dysfunction and oxidative stress consequences.
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Zhao, Zhi-Jun,Yang, Jeong-Ho,Li, Xin,Park, Sang-Hu Elsevier 2016 Materials letters Vol.164 No.-
<P><B>Abstract</B></P> <P>We have investigated the formation of surface wavy structures (wrinkles) depending on the diverse surface conditions of a substrate, and now report the effect of various levels of reflection of incident ultraviolet (UV)-light. UV-curable resin layers with a thickness of 0.15mm were coated on three different surface conditions; transparent glass, fine and rough surface aluminum plate, to compare the formation of wrinkles on each surface. Short irradiations of UV-light for 10, 15, 20, 25 and 30s were exposed, resulting in the weak to full polymerization of the skin of a resin layer, respectively. The wavy structures were formed during thermal curing under room temperature after the short exposure of UV-light. The difference in reflection conditions resulting from the various surface roughnesses of the substrates led to changes in the amounts of polymerization, and the distribution of polymerization intensity through the layer thickness. Due to these different mechanisms, wrinkling shapes were quite distinguished. Through this work, we observed that controllable producing an approximately 33% maximum difference in the line width of wrinkles by using different substrate surface conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of a substrate reflection condition was investigated for diverse generation of surface wrinkles. </LI> <LI> It was studied that the fundamental mechanism on formation of wrinkles by weak-polymerization and thermal curing process. </LI> <LI> Irregular line-shapes of wrinkles with a range of 62–92μm in line width were fabricated by using the effect of substrate reflection conditions. </LI> <LI> Contact angle was varied depending on wrinkle shapes from 63° to 76°. </LI> </UL> </P>
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Studies on the influence factors of wind dynamic responses on hyperbolic cooling tower shells
Jun-Feng Zhang,Qing-Shuai LIU,Yao-Jun Ge,Lin Zhao 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.5
Wind induced dynamic responses on hyperbolic cooling tower (HCT) shells are complicated functions of structure and wind properties, such as the fundamental frequency fmin, damping ratio ζ, wind velocity V, correlationship in meridian direction and so on, but comprehensions on the sensitivities of the dynamic responses to these four factors are still limited and disagree from each other. Following the dynamic calculation in time domain, features of dynamic effects were elaborated, focusing on the background and resonant components σB and σR, and their contributions to the total rms value σT. The σR is always less than σB when only the maximum σT along latitude is concerned and the contribution of σR to σT varies with responses and locations, but the σR couldn’t be neglected for structural design. Then, parameters of the above four factors were artificially adjusted respectively and their influences on the gust responses were illustrated. The relationships of σR and the former three factors were expressed by fitted equations which shows certain differences from the existing equations. Moreover, a new strategy for wind tunnel tests aiming at surface pressures and the following dynamic calculations, which demands less experiment equipment, was proposed according to the influence from meridian correlationship.
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Zhao, Zhi-Jun,Hwang, Soon Hyoung,Kang, Hyeok-Joong,Jeon, Sohee,Bok, Moonjeong,Ahn, Sunggyun,Im, DaJeong,Hahn, Joonku,Kim, Hwi,Jeong, Jun-Ho American Chemical Society 2020 ACS APPLIED MATERIALS & INTERFACES Vol.12 No.1
<P>Herein, we develop an adhesive-free double-faced nanotransfer lithography (ADNT) technique based on the surface deformation of flexible substrates under the conditions of temperature and pressure control and thus address the challenge of realizing the mass production of large-area nanodevices in the fields of optics, metasurfaces, and holograms. During ADNT, which is conducted on a flexible polymer substrate above its glass transition temperature in the absence of adhesive materials and chemical bonding agents, nanostructures from the polymer stamp are attached to the deformed polymer substrate. Various silicon masters are employed to prove our method applicable to arbitrary nanopatterns, and diverse Ag and Au nanostructures are deposited on polymer molds to demonstrate the wide scope of useable metals. Finally, ADNT is used to (i) produce a flexible large-area hologram on the defect-free poly(methyl methacrylate) (PMMA) film and (ii) fabricate a metasurface hologram and a color filter on the front and back surfaces of the PMMA film, respectively, to realize dual functionality. Thus, it is concluded that the use of ADNT can decrease the fabrication time and cost of high-density nanodevices and facilitate their commercialization.</P> [FIG OMISSION]</BR>
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