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남자 대학 세단뛰기 선수들의 도움닫기 마지막 3스트라이드의 유형과 접지와 이지 순간의 운동학적 분석
류재균,장재관,김상도 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.6
The purposes of this study were to examine the characteristics of the kinematic factors of the final three strides before takeoff of a triple jump and to collect the fundamental quantities of motion in order to improve the triple jump performance. The subjects were the 5 Finalists For an actual 16.70m over in the triple jump at the 2003 World Student Games. The last three strides were analysed using three cameras, The x, y, z coordinates of 20 points defining a Fourteen segment model of the human body were used For Further analysis, After smoothing the raw data with a fourth order Butterworth Filter, the centres of gravity of the subjects were calculated. After analyzing the kinematic data during the final three strides, the following findings were obtained: The last three stride Length changes in triple jump did not have a consistent pattern and showed the varieties in jumpers' technical preference. The height of center gravity was different in each event of the last three strides but the lowest center of gravity was the time of touchdown on the board. The maximum horizontal velocity was shown at the second-last and third-last stride takeoff instances.
Flow Instability of Polyvinyl alcohol)/Dimethyl Sulfoxide Solution under Steady Shear
Do, Sung Yeol,Ryu, Chang Yeol,Lee, Yong Rok,Shim, Jae Jin,Noh, Seok Kyun,Kim, Joon Ho,Joo, Sang Woo,Gal, Yeong Soon,Han, Sung Soo,Lyoo, Won Seok SAGE Publications 2011 Polymers & polymer composites Vol.19 No.6
<P>The effects of solution temperature and molecular weight on the rheological responses of poly(vinyl alcohol) (PVA) semidilute solutions (13 g/dL - 19 g/dL) in dimethyl sulfoxide (DMSO) have been studied using PVA with two different number-average degrees of polymerization (P(n)): 1700 and 4000. For the rheological experiments using dynamic shear, the PVA solution with a P(n) of 1700 showed rather simple Newtonian fluid behaviour, whereas that with P(n) of 4000 exhibited non-Newtonian shear thinning behaviour. Steady shear rheology experiments suggested that the lower P(n) PVA solutions were Newtonian fluids, which is consistent with the dynamic shear rheology results. However, an abrupt decrease of shear viscosity at high shear rates was observed for the higher P(n) PVA solutions at lower temperatures, such as 30 degrees C and 50 degrees C. At higher temperatures of 70 degrees C and 90 degrees C, the higher molecular weight PVA solutions exhibited simple shear thinning behaviour without any further complications of flow instability. The fact that temperature plays a critical role in controlling the observed flow instability of the PVA solutions in DMSO strongly suggests that there exist enhanced inter-chain interactions by hydrogen bonding of PVA chains beyond the chain entanglements, particularly for the higher P(n) PVA semidilute solutions at low temperatures. Therefore, it is important to consider both chain entanglements and hydrogen bonding interactions in order to process PVA solutions without causing undesirable flow instability.</P>
Direct visualization of single-molecule membrane protein interactions in living cells
Kim, Do-Hyeon,Park, Soyeon,Kim, Dong-Kyun,Jeong, Min Gyu,Noh, Jungeun,Kwon, Yonghoon,Zhou, Kai,Lee, Nam Ki,Ryu, Sung Ho Public Library of Science 2018 PLoS biology Vol.16 No.12
<▼1><P>Interactions between membrane proteins are poorly understood despite their importance in cell signaling and drug development. Here, we present a co-immunoimmobilization assay (Co-II) enabling the direct observation of membrane protein interactions in single living cells that overcomes the limitations of currently prevalent proximity-based indirect methods. Using Co-II, we investigated the transient homodimerizations of epidermal growth factor receptor (EGFR) and beta-2 adrenergic receptor (β2-AR) in living cells, revealing the differential regulation of these receptors’ dimerizations by molecular conformations and microenvironment in a plasma membrane. Co-II should provide a simple, rapid, and robust platform for visualizing both weak and strong protein interactions in the plasma membrane of living cells.</P></▼1><▼2><P><B>Author summary</B></P><P>Protein–protein interactions govern cellular processes. The majority of these physical interactions previously identified are strong/permanent interactions, which typically remain unbroken even after purification. The weak/transient interactions between proteins have been implicated in the control of dynamic cellular process that maintain cellular homeostasis and trigger signaling cascades upon environmental changes. However, these interactions are poorly investigated, mainly due to the methodological limitations. Here, we have developed a co-immunoimmobilization assay called Co-II that enables the direct visualization of protein–protein interactions in the membrane of living cells at the single-molecule level. Co-II is based on the intuitive concept that if the protein of interest is immobilized, the interacting protein must be co-immobilized. The use of intrinsic protein diffusivity fundamentally overcomes the limitations of proximity-based methods. Using Co-II, we study the transient homodimerizations of EGFR and β2-AR in living cells, which have been implicated in several types of cancers and heart diseases. We show that the dimerization of these receptors is differently regulated by molecular conformations and the microenvironment in the plasma membrane.</P></▼2>
Kim, Do-Hyeon,Kim, Dong-Kyun,Zhou, Kai,Park, Soyeon,Kwon, Yonghoon,Jeong, Min Gyu,Lee, Nam Ki,Ryu, Sung Ho Royal Society of Chemistry 2017 Chemical Science Vol.8 No.7
<▼1><P>Reaction progress kinetic analysis utilizing single molecule trajectories revealed the comprehensive molecular mechanisms of cetuximab induced EGFR endocytosis.</P></▼1><▼2><P>Cellular processes occur through the orchestration of multi-step molecular reactions. Reaction progress kinetic analysis (RPKA) can provide the mechanistic details to elucidate the multi-step molecular reactions. However, current tools have limited ability to simultaneously monitor dynamic variations in multiple complex states at the single molecule level to apply RPKA in living cells. In this research, a single particle tracking-based reaction progress kinetic analysis (sptRPKA) was developed to simultaneously determine the kinetics of multiple states of protein complexes in the membrane of a single living cell. The subpopulation ratios of different states were quantitatively (and statistically) reliably extracted from the diffusion coefficient distribution rapidly acquired by single particle tracking at constant and high density over a long period of time using super-resolution microscopy. Using sptRPKA, a series of molecular mechanisms of epidermal growth factor receptor (EGFR) cellular processing induced by cetuximab were investigated. By comprehensively measuring the rate constants and cooperativity of the molecular reactions involving four EGFR complex states, a previously unknown intermediate state was identified that represents the rate limiting step responsible for the selectivity of cetuximab-induced EGFR endocytosis to cancer cells.</P></▼2>