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排序方式: 共有1023条查询结果,搜索用时 15 毫秒
991.
992.
Pilgun Oh Jeongsik Yun Jae Hong Choi Gyutae Nam Seohyeon Park Tom James Embleton Moonsu Yoon Se Hun Joo Su Hwan Kim Haeseong Jang Hyungsub Kim Min Gyu Kim Sang Kyu Kwak Jaephil Cho 《Liver Transplantation》2023,13(1):2202237
The recent development of high-energy LiCoO2 (LCO) and progress in the material recycling technology have brought Co-based materials under the limelight, although their capacity still suffers from structural instability at highly delithiated states. Thus, in this study, a secondary doping ion substitution method is proposed to improve the electrochemical reversibility of LCO materials for Li-ion batteries. To overcome the instability of LCO at highly delithiated states, Na ions are utilized as functional dopants to exert the pillar effect at the Li sites. In addition, Fe-ion substitution (secondary dopant) is performed to provide thermodynamically stable surroundings for the Na-ion doping. Density functional theory calculations reveal that the formation energy for the Na-doped LCO is significantly reduced in the presence of Fe ions. Na and Fe doping improve the capacity retention as well as the average voltage decay at a cutoff voltage of 4.5 V. Furthermore, structural analysis indicates that the improved cycling stability results from the suppressed irreversible phase transition in the Na- and Fe-doped LCO. This paper highlights the fabrication of high-energy Co-rich materials for high voltage operations, via a novel ion substitution method, indicating a new avenue for the manufacturing of layered cathode materials with a long cycle life. 相似文献
993.
Huen Lee Won-Hi Hong Ji-Ho Yoon Kyu-Min Song Sang-Soo Kwak Jang-Ryol Liu 《Biotechnology Techniques》1992,6(2):127-130
Summary Indole alkaloids, particularly vindoline and catharanthine, were extracted from the leaves ofCatharanthus roseus by supercritical extraction with CO2. The contents of vindoline and catharanthine in the extracts were determined by HPLC and identified by LC/MS. About 52 %(w/w)
of the initial vindoline content, 1.5 mg vindoline/g dry wt leaves, was recovered after extracting this material for 10 h
with the CO2 flow rate of 400 ml/min at 40°C and 150 bar. Vindoline concentration in the extract was 67 %(w/w). 相似文献
994.
Lee Haeng-Soon Kwon Eun-Jeong Kwon Suk-Yoon Jeong Yu-Jeong Lee Eun-Mo Jo Man-Hyun Kim Hyun-Sook Woo In-Sik Shinmyo Atsuhiko Yoshida Kazuya Kwak Sang-Soo 《Molecular breeding : new strategies in plant improvement》2003,11(3):213-220
Superoxide dismutase (SOD) plays an important role in cellular defense against oxidative stress in aerobic organisms. To generate cucumber (Cucumis sativus L.) fruits producing high yields of SOD for an anti-aging cosmetic material as a plant bioreactor, the CuZnSOD cDNA (mSOD1) from cassava was introduced into cucumber fruits by Agrobacterium-mediated transformation using the ascorbate oxidase promoter with high expression in fruits. The bialaphos-resistant shoots were selected on medium containing MS basal salts, 2 mg l–1 BA, 0.1 mg l–1 IAA, 300 mg l–1 claforan, and 2 mg l–1 bialaphos. After 6 weeks of culture on the selection medium, the shoots were transferred to MS medium containing 1 mg l–1 IAA, 300 mg l–1 claforan, 2 mg l–1 bialaphos to induce roots. Southern blot analysis confirmed that the mSOD1 gene was properly integrated into the nuclear genomes of three cucumber plants tested. The mSOD1 gene was highly expressed in the transgenic cucumber fruits, whereas it was expressed at a low level in the transgenic leaves. The SOD specific activity (units/mg protein) in transgenic fruits was approximately 3 times higher than in those of non-transgenic plants. 相似文献
995.
996.
Yoosik Youm Junsol Kim Seyul Kwak Jeanyung Chey 《Proceedings. Biological sciences / The Royal Society》2021,288(1944)
To avoid polarization and maintain small-worldness in society, people who act as attitudinal brokers are critical. These people maintain social ties with people who have dissimilar and even incompatible attitudes. Based on resting-state functional magnetic resonance imaging (n = 139) and the complete social networks from two Korean villages (n = 1508), we investigated the individual-level neural capacity and social-level structural opportunity for attitudinal brokerage regarding gender role attitudes. First, using a connectome-based predictive model, we successfully identified the brain functional connectivity that predicts attitudinal diversity of respondents'' social network members. Brain regions that contributed most to the prediction included mentalizing regions known to be recruited in reading and understanding others’ belief states. This result was corroborated by leave-one-out cross-validation, fivefold cross-validation and external validation where the brain connectivity identified in one village was used to predict the attitudinal diversity in another independent village. Second, the association between functional connectivity and attitudinal diversity of social network members was contingent on a specific position in a social network, namely, the structural brokerage position where people have ties with two people who are not otherwise connected. 相似文献
997.
K. H. Jung S. S. Kwak S. W. Kim C. Y. Choi G. S. Heo J. R. Liu 《Biotechnology Techniques》1992,6(4):305-308
Summary To produce economically important indole alkaloids by cell culture, we have selected protoclones ofCatharanthus roseus for high yields of catharanthine and ajmalicine. Protoplasts were enzymatically isolated from suspension-cultured cells.
Protoclone VPC-10 produced catharanthine at 5.9 μg/g fresh wt of cells after 10 days of culture, although the original cell
line did not produce it at a level detectable by HPLC. Under the same conditions, protoclone VPC-15 produced ajmalicine at
133.6 μg/g, which was about 3 times the productivity of the original cell line. In addition, the indole alkaloids were qualitatively
confirmed by LC-MS. 相似文献
998.
Sungjong Kwak Elana Brief Denis Langlais Neil Kitson Michel Lafleur Jenifer Thewalt 《生物化学与生物物理学报:生物膜》2012,1818(5):1410-1419
Ethanol is used in a variety of topical products. It is known to enhance the permeability of the skin by altering the ability of the stratum corneum (SC) intercellular membranes to form an effective barrier. In addition, ethanol and other alcohols are key components of antiseptic gels currently used for hand wash. Using infrared and deuterium NMR spectroscopy as well as calorimetry, we have investigated the effect of ethanol on a model membrane composed of lipids representing the three classes of SC lipids, an equimolar mixture of N-palmitoylsphingosine (ceramide), palmitic acid and cholesterol. Ethanol is found to influence the membrane in a dose dependent manner, disrupting packing and increasing lipid motion at low concentrations and selectively extracting lipids at moderate concentrations. 相似文献
999.
Brenda R. Kwak Paolo Silacci Nikos Stergiopulos Daniel Hayoz Paolo Meda 《Cell communication & adhesion》2005,12(5):261-270
Hemodynamic forces play a critical role in atherogenesis, as evidenced by the focal pattern of development of atherosclerotic lesions. Whereas disturbed flow in the branches and curved regions of large arteries is proatherogenic, laminar flow in the straight parts of vessels is atheroprotective. In addition, hypertension and age-related changes in arterial stiffness are important risk factors of the disease. Hemodynamic forces induce various changes in the structure and function of vascular endothelium, many of which reflect alterations in gene expression. Endothelial cells are linked by gap junctions, which facilitate the propagation of electrical and chemical signals along the vascular wall. Using an in vitro perfusion system, we investigated the effects of pulsed unidirectional and oscillatory flows in combination with different levels of hydrostatic pressure and circumferential stretch on the expression of Cx43 in endothelial cells. Our results show that shear stress and circumferential stretch, but not pressure, modulate the expression of Cx43. In view of the distribution of this protein along the vascular tree, our findings provide new insights into the role of mechanical forces on gap junctional communication in regions prone to the development of atherosclerosis. 相似文献
1000.