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Mechanical properties of aluminum-based nanocomposite reinforced with fullerenes

Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 47-52页

作者： Kwangmin CHOI jiyeon seo Donghyun BAE Hyunjoo CHOI School of Advanced Materials Engineering Kookmin University School of Advanced Materials Engineering Yonsei University

The strengthening effect of fullerenes in aluminum matrix composites was investigated. The composites are produced using a two-step ball-milling technique combined with a hot rolling process. First, fullerene aggregates, where fullerene molecules initially come together to form giant particles(~200 μm in diameter) via van der Waals bonding, are shattered into smaller particles(~1 μm in diameter) by planetary milling. Second, primarily ball-milled fullerenes are dispersed in aluminum powder via attrition milling. Finally, aluminum/fullerene composite powder is consolidated by hot-rolling at 480 °C. For the composite sheet, grain refinement strengthening and dispersion hardening by fullerenes are accomplished at the same time, thereby exhibiting HV ~222 of Vickers hardness(e.g., ~740 MPa of yield strength) with only 2%(volume fraction) of fullerenes.

关键词： aluminum fullerenes ball-milling powder metallurgy composites

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A single-domain protein catenane of dihydrofolate reductase

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National Science Review 2023年第11期10卷 128-137页

作者： Jing Fang Tianzuo Li jiyeon Lee Dahye Im Lianjie Xu Yajie Liu Jongcheol seo Wen-Bin Zhang Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry & Physics of Ministry of EducationCenter for Soft Matter Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking University Department of Chemistry Pohang University of Science and Technology (POSTECH) Beijing Academy of Artificial Intelligence

A single-domain protein catenane refers to two mechanically interlocked polypeptide rings that fold synergistically into a compact and integrated structure, which is extremely rare in nature. Here, we report a single-domain protein catenane of dihydrofolate reductase(cat-DHFR). This design was achieved by rewiring the connectivity between secondary motifs to introduce artificial entanglement and synthesis was readily accomplished through a series of programmed and streamlined post-translational processing events in cells without any additional in vitro reactions. The target molecule contained few exogenous motifs and was thoroughly characterized using a combination of ultra-performance liquid chromatography–mass spectrometry, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, protease cleavage experiments and ion mobility spectrometry–mass spectrometry. Compared with the linear control, cat-DHFR retained its catalytic capability and exhibited enhanced stability against thermal or chemical denaturation due to conformational restriction. These results suggest that linear proteins may be converted into their concatenated single-domain counterparts with almost identical chemical compositions, well-preserved functions and elevated stabilities, representing an entirely new horizon in protein science.

关键词： cellular synthesis catenane protein domain chemical topology DHFR

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Nitrogen mass balance in a constructed wetland treating piggery wastewater effluent

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Journal of Environmental Sciences 2014年第6期26卷 1260-1266页

作者： Soyoung Lee Marla C.Maniquiz-Redillas jiyeon Choi Lee-Hyung Kim Water Environment Research Dept. National Institute of Environmental Research Hwangyeong-ro 42 Seo-gu Incheon 404-708 Korea Department of Civil and Environmental Engineering Kongju National University 275 Budaedong Seobukgu Cheonan Chungnamdo 331-717Korea

The nitrogen changes and the nitrogen mass balance in a free water surface flow constructed wetland （CW） using the four-year monitoring data from 2008 to 2012 were estimated. The CW was composed of six cells in series that include the first settling basin （Cell 1）, aeration pond （Cell 2）, deep marsh （Cell 3）, shallow marsh （Cell 4）, deep marsh （Cell 5） and final settling basin （Cell 6）. Analysis revealed that the NH4＋-N concentration decreased because of ammonification which was then followed by nitrification. The NO4＋-N and NO4＋-N were also further reduced by means of microbial activities and plant uptake during photosynthesis. The average nitrogen concentration at the influent was 37,819 kg/year and approximately 45% of that amount exited the CW in the effluent. The denitrification amounted to 34% of the net nitrogen input, whereas the accretion of sediment was only 7%. The biomass uptake of plants was able to retain only 1% of total nitrogen load. In order to improve the nutrient removal by plant uptake, plant coverage in four cells （i.e., Cells 1, 3, 4 and 5） could be increased.

关键词： constructed wetland livestock wastewater nitrogen mass balance plant uptake sediment

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Scalp electroacupuncture at the Baihui acupoint (DU 20) improves functional recovery in rats with cerebral ischemia Association with increased expression of vascular endothelial growth factors

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Neural Regeneration Research 2011年第36期6卷 2822-2828页

作者： Min-Wook Kim You Chul Chung Hee Chan Jung Moon-seo Park Young-Min Han Yong-An Chung Lee-So Maeng Sang-In Park jiyeon Lim Seung Chan Kim Woo-seok Im Jin Young Chung Minky Kim Manho Kim Institute of Catholic Integrative Medicine (ICIM) Incheon St. Mary’s Hospital Catholic University of Korea Incheon Korea Department of Rehabilitation Medicine Catholic University of Korea Seoul Korea Department of Neurology Seoul National University Hospital SNUMRC Seoul Korea Department of Biotechnology Yonsei University Seoul Korea Department of Neurology Seoul Medical Center Seoul Korea

In this study, we induced cerebral infarction in rats by occluding the right middle cerebral artery, and tested the effects of electroacupuncture at the Baihui acupoint （DU 20）. Motor and sensory function was tested using Garcia’s scale and motor weakness grading, and the expression of vascular endothelial growth factor in the brain was quantified using immunoblotting and immunohistochemistry. We found that scalp electroacupuncture at DU 20 significantly improved motor performance and sensory function in rats with stroke, and this was accompanied by an increased expression of vascular endothelial growth factor in the ischemic brain tissue and peri-ischemic area. In addition, Pearson correlation analysis showed that the improvements in functional recovery were correlated with the increased expression of vascular endothelial growth factor.

关键词： electroacupuncture cerebrovascular disorder vascular endothelial growth factor Baihui acupoint functional improvement

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