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RISS 인기검색어
- 검색키워드
- 저자 : Haidong Yu (검색결과 6 건)
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Stiffness Improvement of Aerostatic Bearing by Separating-Pad-Based Passive Compensation
Haidong Hu,Youmin Rong,Hao Wu,Yu Huang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.1
With the development of ultra-precision machining technology, the aerostatic bearings with high stiffness are needed urgently. This paper proposes a new aerostatic bearing structure with split design, which can passively compensate the load displacement caused by the change of film thickness through the pressure feedback of the shell. The static characteristics of the bearing are analyzed by computational fluid dynamics analysis and fluid–structure interaction simulation. The effectiveness of the structure is verified by comparative experiments. The results show that the static stiffness of the bearing is improved by 171% within a certain load range, the dynamic stiffness is increased by up to 30% under low frequency excitation and capacity is better than that of the conventional aerostatic bearing.
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Bai, Rui,Sen, Aritro,Yu, Zhihui,Yang, Gang,Wang, Haidong,Fan, Ruiwen,Lv, Lihua,Lee, Kyung-Bon,Smith, George W,Dong, Changsheng Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.4
The objective of the present studies was to develop and validate a system for isolation, purification and extended culture of pigment-producing cells in alpaca skin (melanocytes) responsible for coat color and to determine the effect of alpha melanocyte stimulating hormone treatment on mRNA expression for the melanocortin 1 receptor, a key gene involved in coat color regulation in other species. Skin punch biopsies were harvested from the dorsal region of 1-3 yr old alpacas and three different enzyme digestion methods were evaluated for effects on yield of viable cells and attachment in vitro. Greatest cell yields and attachment were obtained following dispersion with dispase II relative to trypsin and trypsin-EDTA treatment. Culture of cells in medium supplemented with basic fibroblast growth factor, bovine pituitary extract, hydrocortisone, insulin, 12-O-tetradecanolphorbol-13-acetate and cholera toxin yielded highly pure populations of melanocytes by passage 3 as confirmed by detection of tyrosinase activity and immunocytochemical localization of melanocyte markers including tyrosinase, S-100 and micropthalmia-associated transcription factor. Abundance of mRNA for tyrosinase, a key enzyme in melanocyte pigment production, was maintained through 10 passages showing preservation of melanocyte phenotypic characteristics with extended culture. To determine hormonal responsiveness of cultured melanocytes and investigate regulation of melanocortin 1 receptor expression, cultured melanocytes were treated with increasing concentrations of ${\alpha}$-melanocyte stimulating hormone. Treatment with ${\alpha}$-melanocyte stimulating hormone increased melanocortin receptor 1 mRNA in a dose dependent fashion. The results demonstrated culture of pure populations of alpaca melanocytes to 10 passages and illustrate the potential utility of such cells for studies of intrinsic and extrinsic regulation of genes controlling pigmentation and coat color in fiber-producing species.
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ZIF-67 modified MXene/sepiolite composite membrane for oil–water separation and heavy metal removal
Qiuxiang Wang,Zongxue Yu,Ximei Zhu,Qingcan Xiang,Haidong Chen,Yao Pang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
In this study, polyvinylpyrrolidone (PVP) was used as a cross-linking agent leading to ZIF-67 in-situ growon the surface of sepiolite (Sep) to increase the specific surface area and space volume of Sep. Subsequently, a hydrothermal synthesis method was used to form a stable super-hydrophilic compositemembrane from the composite MXene by polydopamine. Compared to the MXene/PDA/Sep (MPS) compositemembrane, the composite membrane with ZIF-67 exhibited improved hydrophilicity and heavymetal separation. In addition, the introduction of negatively charged Sep@ZIF-67–24 (SZ-24) increasedthe number of adsorption active sites and negative potential for the surface of the membrane, and thiswas conducive to the demulsification and adsorption of oil–water emulsions. The MXene/PDA/Sep@ZIF-67–1 (MSZ-1) composite membrane had excellent separation effects on surfactant-stabilizedemulsions (SSEs) and surfactant-free emulsions (SFEs) oil–water emulsions which were above 99.4 %. Furthermore, the separation effect on oil–water, under extreme water conditions, was greater than99 %. The MSZ-1 composite membrane can achieve excellent separation of heavy metal ions, especiallyCu2+ that the rejection was 79.9 %, under high flux and extreme conditions. Therefore, the MSZ-1 compositemembrane has broad application prospects in oil–water treatment and heavy metal separation.
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Biosorption mechanism of Zn from aqueous solution by spent substrates of pleurotus ostreatus
XiaoJing Hu,JuanJuan Qu,LiLong Yan,Haidong Gu,TingTing Zang,Yu Jin 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.11
To solve the problem of heavy metal pollution and agricultural wastes reclamation, spent substrate of pleurotusostreatus (SSPO) was used as adsorbent to remove Zn2+from aqueous solution. The biosorption of zinc ions on SSPOwas studied as a function of the solution pH, temperature and initial Zn2+concentration. The equilibrium sorption datawere well represented by linear Langmuir isotherm models with R2value of 0.9955 and non-linear Freundlich withR2value of 0.9973. The BET surface area of SSPO can reach 51.16 m2g−1. SEM-EDX and XRD revealed that (NH4)2Zn·H2O and Zn2PO4(OH) were the main compounds in metal-loaded SSPO. FTIR analysis indicated the governing func-tional groups such as O-H, N-H and P=O played an important role in biosorption. The desorption studies showed thereversibility of SSPO. The results indicate that SSPO is a potential adsorbent in wastewater treatment due to its greatsorption capacity and low cost.
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Expression, Purification and Properties of Shikimate Dehydrogenase from Mycobacterium Tuberculosis
Zhang, Xuelian,Zhang, Shunbao,Hao, Fang,Lai, Xuhui,Yu, Haidong,Huang, Yishu,Wang, Honghai Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.5
Tuberculosis, caused by Mycobacterium tuberculosis, continues to be one of the main diseases to mankind. It is urgent to discover novel drug targets for appropriate antimicrobial agents against this human pathogen. The shikimate pathway is onsidered as an attractive target for the discovery of novel antibiotics for its essentiality in bacteria and absence in mammalian cells. The Mycobacterium tuberculosis aroE-encoded shikimate dehydrogenase was cloned, expressed and purified. Sequence alignment analysis shows that shikimate dehydrogenase of Mycobacterium tuberculosis exhibit the pattern of G-X-(N/S)-V-(T/S)-X-PX-K, which is highly conserved within the shikimate dehydrogenase family. The recombinant shikimate dehydrogenase spectrum determined by CD spectroscopy showed that the percentages for $\alpha$-helix, $\beta$-sheet, $\beta$-turn, and random coil were 29.2%, 9.3%, 32.7%, and 28.8%, respectively. The enzymatic characterization demonstrates that it appears to be fully active at pH from 9.0 to 12, and temperature $63^{\circ}C$. The apparent Michaelis constant for shikimic acid and $NADP^+$ were calculated to be about $29.5\;{\mu}M$ and $63\;{\mu}M$. The recombinant shikimate dehydrogenase catalyzes the substrate in the presence of $NADP^+$ with an enzyme turnover number of $399\;s^{-1}$. Zymological studies suggest that the cloned shikimate dehydrogenase from M. tuberculosis has a pretty activity, and the work should help in the discovery of enzyme inhibitors and further of possible antimicrobial agents against Mycobacterium tuberculosis.
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