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Fulin Wen,Jianhua Zhao,Kaiqing Feng,Miaowang Yuan,Dengzhi Zheng,Cheng Gu,Bei Xu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
In this paper, TC4/AZ91D bimetallic composites has been prepared by liquid–solid compound casting process adaptingvarious thickness of Cu coating. The effects of Cu coating thickness on the evolution of interface microstructures and jointmechanical properties are investigated. The results indicate that metallurgical bonded joints are obtained with Cu coatingthickness ranging from 36.7 to 51.4 μm. With the increase of Cu coating thickness, the interface microstructure evolvesfrom δ-Mg + Mg2Cueutectic structure to Mg–Cu intermetallic compound (IMC) Cu2Mg+ Mg2Cuand Mg–Al–Cu ternaryintermetallic compound. The calculation results of formation enthalpy and chemical potential of Mg–Al–Cu system suggestthat Cu element prefers to react with Mg element and formed Mg–Cu IMC. In particular, when Cu coating thickness reaches36.7 μm, the average shear strength of the bimetal reaches a maximum of 65.3 MPa. Further increasing Cu coating thicknessleads to the generation of thick Mg2CuIMC layer and Mg2Cu+ Cu2Mgmixed IMC layer which are proved to be harmful tothe shear strength of TC4/AZ91D bimetals. All the fracture surfaces of the bimetallic composites exhibite to have a brittlefracture morphology. However, the fracture location is different with each other. For Cu coating thickness of 36.7 μm, theinterface fractures at the δ-Mg + Mg2Cueutectic structure, while the interface fractures at the Cu2Mg+ Mg–Al–Cu ternaryintermetallic layers when Cu coating thickness is 44.2 μm and 51.4 μm.
文學龍,裵正烈,황인성,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)
This study is to investigate the influence of W/C and fineness modulus of aggregate on the bleeding of concrete. According to the result, the lower W/C is, the less bleeding occurs. As for the properties of bleeding with the variation of fineness modulus, the amount of bleeding is small with the continuous grading in the middle of the standard grading range in the case of coarse aggregate, and it grows smaller with a decrease of fineness modulus in the case of fine aggregate. Therefore, it proves that using coarse aggregate with the continuous grading in the middle of the standard grading range and fine aggregate with smaller fineness modulus in the standard grading range is the effective method for reducing bleeding at the same W/C.
Function and Regulation Mechanism of Cyclin E1 during Development of Early Porcine Embryos
Zheng-Wen Nie,Jing Guo,Duk-Jung Kim,Nam-Hyung Kim,Xiang-Shun Cui 한국동물생명공학회(구 한국동물번식학회) 2017 발생공학 국제심포지엄 및 학술대회 Vol.2017 No.10
Cyclin E1 (CCNE1) is a core component of cell cycle regulation that drives the transition into the S phase. CCNE1 plays critical roles in cell cycle, cell proliferation, and cellular functions. However, the function of CCNE1 in early embryonic development is limited. In the present study, the function and expression of Ccne1 in porcine early parthenotes were examined. Immunostaining experiments showed that CCNE1 localized in the nucleus, starting at the four-cell stage. Knockdown of Ccne1 by double-stranded RNA resulted in the failure of blastocyst formation and induced blastocyst apoptosis. Ccne1 depletion increased expression of the pro-apoptotic gene Bax, and decreased the expression of Oct4 and the rate of inner cell mass (ICM)/trophectoderm formation. The results indicated that CCNE1 affects blastocyst formation by inducing cell apoptosis and ICM formation during porcine embryonic development.
( Zheng Wen Wang ),( An Kai Xu ),( Ting Cheng Zhu ) 한국식물학회 2008 Journal of Plant Biology Vol.51 No.2
We surveyed the bud demography of Leymus chinensis L. plants along a soil-moisture gradient that was caused by a flood in 1998 on the Song-nen Plain in northeastern China. The number of vegetative buds per ramet was influenced by soil water content, with regression curves being quadratic and the opening of the parabola pointing downward. In addition, the optimum regression models for the numbers of rhizomatous buds and tiller buds relative to soil water resulted in a quadratic parabola and exponential curve, respectively. Vegetative buds flourished between August and October, with plants producing more of those buds on flooded plots than on control sites. The number of rhizomatous buds per ramet was much higher than for tiller buds throughout most of the growing season, and production of the former was more apt to be affected by soil water status. This observed superiority of rhizomatous bud production was thought to be a consequence of the whole-plant adjustment that was stimulated by an abnormally high moisture content. It could also be interpreted as a strategy for escape from disadvantageous overly wet conditions. Moreover, the position-based preference for bud emergence along the ramets could be an underlying mechanism for selective ramet placement.
Thiamethoxam Induces Meiotic Arrest and Affects Embryo Developmental Potential of Bovine Oocytes
Zheng-Wen Nie,Ying-Jie Niu,Wenjun Zhou,Yong-Han Kim,Kyung-Tae Shin,Xiang-Shun Cui 한국수정란이식학회 2018 한국수정란이식학회 학술대회 Vol.2018 No.11
Thiamethoxam (TMX) is a neonicotinoid insecticide. Residues of TMX have been detected in various crops. Although it has specific high toxicity to insects and is designed to exterminate them, the toxicity has also found in mammals recently. Differ from acetylcholine toxicity, TMX has peroxide toxicity in mammals. Matured oocytes have the capacity of fertilization, but oocytes own abundant mitochondria and its maturation is vulnerable to reactive oxygen species (ROS). Excessive production of reactive oxygen species (ROS) can override antioxidant defenses, produce oxidative stress and DNA damage that triggers apoptosis and necrosis in organisms. However little is known about the harm of ROS induced by TMX during oocytes maturation. Here, bovine germ-vesicle (GV) oocytes were cultured to metaphase of the second meiosis (MII) stage in vitro with or without TMX. During this process, oocytes were evaluated by various methods. Microscopic examination showed that 1.6 mM TMX significantly inhibited the maturation process in which oocytes were arrested before MI stage or between MI and MII stage. Correspond to this two periods, immunofluorescence staining and enzyme activity analysis showed that active CDC25 and CDC2 reduced in TMX group compared to control; time lapse and immunofluorescence staining gave results that Cyclin B could not be degraded, actin cap could not form, and Bub3 could not be removed from kinetochores. In addition, MII oocytes exposed to TMX showed disordered chromosomes and spindle. To study further, oocytes cultured for 24 h were analyzed. On the one hand, these oocytes in TMX group accumulated more ROS and produced significantly decreased mitochondrial membrane potential and increased apoptotic signal compared to control by methods of quantities for dichlorodihydrofluorescein diacetate (DCHFDA), 5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide and Annexin-V, but the level of γH2AX protein in TMX group did not decline significantly compared with control. On the another hand, these oocytes were activated to be parthenogenetic embryos and cultured. Assessment for embryo development showed decreased rates of cleavage, morula and blastocyst in TMX group compared to control in vitro. In conclusion, these results suggest that ROS induced by TMX results in dysfunction of mitochondria and apoptosis, which block bovine oocytes to MI stage, trap them at AI/TI stage and trigger disordered chromosomes and spindle at MII stage. Additionally, MII oocytes with poor qualities result from TMX lose abilities to cleavage and develop to be morulae and blastocysts.
Design of Micro Biopsy Device for Wireless Autonomous Endoscope
Wen-Wen Chen,Guo-Zheng Yan,Hua Liu,Ping-Ping Jiang,Zhi-Wu Wang 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Well-established technology that provides assistance from outside the patient may soon give way to alternative approaches that bythe wireless robotic mechanisms inside the patient through natural orifices. For this study, two kinds of micro biopsy mechanisms weredeveloped for capsule endoscope which could traverse the gut environment automatically. This mobility allows the biopsy device tomove to the area of interest to sample specific tissues. Based on the medical and mechanism considerations, we concerned on designprecise biopsy jaw with sufficient cutting force, and the biopsy process should be safe, repeatable and visible. The lead-screw linkagesystem that actuated jaw of biopsy allowing for large force production. Using one micro-motor, the biopsy process was carried outquickly by three motions: stretching to sampling point; bite and cutting off; withdrawing into capsule body with the sample. With thecontrol and vision system, the biopsy process could compete automatically. The robot was capable of traversing in the gut environmentwirelessly and had been successfully used to biopsy gut tissue in vitro. In addition, experimental analysis of the biopsy mechanismshowed good results towards more elaborate tissue manipulation in the future.
Accurate MAC Frame Synchronization Scheme for IEEE802.11 in TDMA -Based Ad Hoc Network
Zheng Wen,Jaeho Choi 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
A novel self synchronization algorithm is proposed in which the advantage of RSB is exploited for the leading node election and a more sophisticated clock updating is utilized to enable a better performance. The proposed scheme is applied to support real-time applications using TDMA MAC.
Wen-Zheng Pan,Xiao-Wei Huang,Kang-Bi Wei,Chun-Mei Zhang,Dong-Mei Yang,Jun-Mei Ding,Ke-Qin Zhang 한국미생물학회 2010 The journal of microbiology Vol.48 No.2
The geothermal sites near neutral and alkalescent thermal springs in Tengchong Rehai National Park were examined through cultivation-dependent approach to determine the diversity of thermophilic fungi in these environments. Here, we collected soils samples in this area, plated on agar media conducive for fungal growth, obtained pure cultures, and then employed the method of internal transcribed spacer (ITS)sequencing combined with morphological analysis for identification of thermophilic fungi to the species level. In total, 102 strains were isolated and identified as Rhizomucor miehei, Chaetomium sp., Talaromyces thermophilus, Talaromyces byssochlamydoides, Thermoascus aurantiacus Miehe var. levisporus, Thermomyces lanuginosus, Scytalidium thermophilum, Malbranchea flava, Myceliophthora sp. 1, Myceliophthora sp. 2,Myceliophthora sp. 3, and Coprinopsis sp. Two species, T. lanuginosus and S. thermophilum were the dominant species, representing 34.78% and 28.26% of the sample, respectively. Our results indicated a greater diversity of thermophilic fungi in neutral and alkaline geothermal sites than acidic sites around hot springs reported in previous studies. Most of our strains thrived at alkaline growth conditions.