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Zhong-yu Si,Zhong-xiao Sun,Lianwei Ye,Ai-jun Gao,Yu Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
In recent years, with the increasing demand for carbon fiber-reinforced polymer (CFRP), the recycling of its wastehas become a serious problem that restricts the wider application of CFRP. This study used a benzyl alcohol/NaOH system atatmospheric pressure to degrade the CFRP of epoxy-resin matrix cured by anhydride, and the influence of NaOH dosage ondegradation rate was investigated. The degradation mechanism of the resin was analyzed using Fourier transform infraredspectroscopy, gas chromatography-mass spectrometry and Electro-Spray Ionization-Mass Spectroscopy. The structure andproperties of the recycled carbon fibers were characterized using scanning electron microscopy, X-ray photoelectronspectroscopy and a monofilament tensile strength test. The experimental results indicated that the benzyloxy nucleophilicgroup produced by benzyl alcohol in alkaline conditions selectively attacked the cross-linking ester bond of the resin andbroke the c ross-linking point. Finally, the resin was degraded by removing the curing agent. When the m ass ratio of NaOH toCFRP (w(NaOH):w(CFRP)) was not under 1:1 and the reaction conditions were 190 °C, 1 h and atmospheric pressure, thedegradation rate of the resin reached 98.4 %. The degradation products of the resin were insoluble in benzyl alcohol andprecipitated, which was conducive to the recovery and reuse of the benzyl alcohol. The surface oxygen content of therecycled carbon fiber was similar to that of the original carbon fiber, and the tensile strength of recycled carbon fibermonofilament remained above 95 % of the original.
Mechanical Properties of Sprayable Fiber Reinforced Strain-Hardening Cement Composite (SHCC)
Yu, Zhong Jie,Lee, Mi Hwa,Yun, Hyun Do Trans Tech Publications, Ltd. 2013 Applied mechanics and materials Vol.372 No.-
<P>The use of strain-hardening cement composite (SHCC), which exhibits metal-like deformation behavior and has ability to restrict crack opening, as a retrofit material for seismic retrofitting of existing infrastructures, has been the subject of high expectations. In this work, Three SHCC mixtures including different chemical or mineral admixtures were prepared and evaluated based on the mechanical properties, such as flow, sprayability, compressive and uniaxial tensile performances. All SHCC mixtures were reinforced with polyvinyl alcohol (PVA) fibers at volume fraction of 2.2%. Mechanical properties of each SHCC mixture were measured and evaluated after mixing, pumping, and shotcreting. Experimental results indicated that the compressive strength and elastic modulus of three SHCC mixtures increased almost linearly according to shotcreting procedure from mixer to nozzle. And the uniaxial tensile of SHCC mixture (SHCC-AE) with AE agent was superior to the other SHCC mixtures (SHCC-MC and-N).</P>
H-mode experimental integrated modeling of impurity injection to control divertor heat flux on HL-2A
Yu Peng,Huang Qianhong,Zhong Yijun,Wu Ting,Wang Jun,Wang Zhanhui,Gong Xue-yu 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.8
Based on the METIS integrated modeling platform, combined with the experimental data of the #34512 shot detached divertor operation on the HL-2A, this paper selects suitable physical models, and compares and analyzes the integrated modeling results with the experimental results. The modeling results are in good agreement with the experimental results. On this basis, the reason for the decrease of the peak heat fux on the divertor targets is investigated using the METIS simulator. The results show that the two factors of entering the H-mode and the radiation enhancement efect generated by impurity injection work together to reduce the heat fow on the targets. Finally, the diferent efects of N, Ar and Ne impurity gases on the heat fux reduction of the targets are simulated under the condition that the plasma line-average efective charge (Zef) is kept unchanged. The results show that N and Ar are both better than Ne in controlling the heat fow on the targets, and N has the best compatibility in the core, which can not only reduce the boundary heat fow but also maintain the core confnement performance.
Wafer-scale synthesis of monolayer two-dimensional porphyrin polymers for hybrid superlattices
Zhong, Yu,Cheng, Baorui,Park, Chibeom,Ray, Ariana,Brown, Sarah,Mujid, Fauzia,Lee, Jae-Ung,Zhou, Hua,Suh, Joonki,Lee, Kan-Heng,Mannix, Andrew J.,Kang, Kibum,Sibener, S. J.,Muller, David A.,Park, Jiwoon American Association for the Advancement of Scienc 2019 Science Vol.366 No.6471
<P><B>Single-layer porphyrin polymerization</B></P><P>Two-dimensional polymers can be made as monolayer sheets through controlled synthesis at an interface. However, it is often difficult to create intact sheets over large areas that can be transferred onto substrates. Zhong <I>et al.</I> polymerized derivatized porphyrin molecules during laminar flow at a sharp pentane-water interface to form sheets that are 5 centimeters in diameter (see the Perspective by MacLean and Rosei). The authors used electron microscopy and spectroscopy to confirm that they had produced intact monolayers. These films were then transferred onto monolayer sheets of molybdenum disulfide to form superlattices for use as capacitors.</P><P><I>Science</I>, this issue p. 1379; see also p. 1308</P><P>The large-scale synthesis of high-quality thin films with extensive tunability derived from molecular building blocks will advance the development of artificial solids with designed functionalities. We report the synthesis of two-dimensional (2D) porphyrin polymer films with wafer-scale homogeneity in the ultimate limit of monolayer thickness by growing films at a sharp pentane/water interface, which allows the fabrication of their hybrid superlattices. Laminar assembly polymerization of porphyrin monomers could form monolayers of metal-organic frameworks with Cu<SUP>2+</SUP> linkers or covalent organic frameworks with terephthalaldehyde linkers. Both the lattice structures and optical properties of these 2D films were directly controlled by the molecular monomers and polymerization chemistries. The 2D polymers were used to fabricate arrays of hybrid superlattices with molybdenum disulfide that could be used in electrical capacitors.</P>
( Yu Xuan Tian ),( Jie Chen ),( Hui Min Yu ),( Zhong Yao Shen ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.2
Three combinations of molecular chaperones from Escherichia coli (i.e., DnaK-DnaJ-GrpEGroEL- GroES, GroEL-GroES, and DnaK-DnaJ-GrpE) were overproduced in E. coli BL21, and their in vitro stabilizing effects on a nitrile hydratase (NHase) were assessed. The optimal gene combination, E. coli groEL-groES (ecgroEL-ES), was introduced into Rhodococcus ruber TH3. A novel engineered strain, R. ruber TH3G was constructed with the native NHase gene on its chromosome and the heterologous ecgroEL-ES genes in a shuttle plasmid. In R. ruber TH3G, NHase activity was enhanced 37.3% compared with the control, TH3. The in vivo stabilizing effect of ecGroEL-ES on the NHase was assessed using both acrylamide immersion and heat shock experiments. The inactivation behavior of the in vivo NHase after immersion in a solution of dynamically increased concentrations of acrylamide was particularly evident. When the acrylamide concentration was increased to 500 g/l (50%), the remaining NHase activity in TH3G was 38%, but in TH3, activity was reduced to 10%. Reactivation of the in vivo NHases after varying degrees of inactivation was further assessed. The activity of the reactivated NHase was more than 2-fold greater in TH3G than in TH3. The hydration synthesis of acrylamide catalyzed by the in vivo NHase was performed with continuous acrylonitrile feeding. The final concentration of acrylamide was 640 g/l when catalyzed by TH3G, compared with 490 g/l acrylamide by TH3. This study is the first to show that the chaperones ecGroEL-ES work well in Rhodococcus and simultaneously possess protein-folding assistance functions and the ability to stabilize and reactivate the native NHases.
Yu, Zhong Jie,Han, Seung Ju,Jang, Seok Joon,Yun, Hyun Do Trans Tech Publications, Ltd. 2014 Applied Mechanics and Materials Vol.525 No.-
<P>This study investigates experimentally the applicability of selectively weakening retrofit for existing and non-ductile squat shear walls. To evaluate the effect of vertical seams on the wall panel on the hysteretic behavior and failure mode of Strain-Hardening Cement Composite (SHCC) squat shear walls, two 1/3 scale shear walls with vertical seams as a variable were made and tested under reversed cyclic loadings. All specimens had same rectangular cross-section 1,100mm¡¿50mm, with panel height 600mm. The vertical seam is 40mm wide and 260mm high and 460 high. SHCC for wall specimens was supplied by a local ready mix company with specified strength of 50MPa. The test results of this study; length of the slit is increased in squat shear wall, which the specimen became load-carrying capacity and stiffness. But have vertical silt, the squat shear wall shows aspects of ductility destruction.</P>
Yu-Min Zhong,Suvipaporn Siripornpitak,Rong-Zhen Ouyang,Wei-Hui Xie,구현우 아시아심장혈관영상의학회 2021 Cardiovascular Imaging Asia Vol.5 No.4
Cardiac magnetic resonance imaging (CMR) is an important noninvasive diagnostic imaging modality for evaluating children with congenital heart disease. However, pediatric CMR is not widely performed in Asia. This survey was conducted to check the current status of our clinical practice of pediatric CMR. Results from a web-based questionnaire were obtained from 12 hospitals in seven Asian countries. The questionnaire inquired about hospital size and type, staffing and operators, MRI scanner specifications, contrast agent type(s) and intravenous injection method(s), sedation, CMR protocols, clinical indications, postprocessing software, major research topics, major obstacles to clinical practice and research, and the expectation of education. This survey demonstrated that pediatric CMR protocols mostly correlate with expert consensus statements from other societies. Limited resources and high workloads were primary obstacles to clinical practice and research. The development of abbreviated protocols and good education programs may be helpful to improve our situation.