Conformational change of erythroid α-spectrin at the tetramerization site upon binding β-spectrin

Long, Fei,McElheny, Dan,Jiang, Shaokai,Park, Sunghyouk,Caffrey, Michael S.,Fung, Leslie W.-M. Wiley-Blackwell Publishing, Inc. 2007 Protein science Vol. No.

<P>We previously determined the solution structures of the first 156 residues of human erythroid alpha-spectrin (SpalphaI-1-156, or simply Spalpha). Spalpha consists of the tetramerization site of alpha-spectrin and associates with a model beta-spectrin protein (Spbeta) with an affinity similar to that of native alpha- and beta-spectrin. Upon alphabeta-complex formation, our previous results indicate that there is an increase in helicity in the complex, suggesting conformational change in either Spalpha or Spbeta or in both. We have now used isothermal titration calorimetry, circular dichroism, static and dynamic light scattering, and solution NMR methods to investigate properties of the complex as well as the conformation of Spalpha in the complex. The results reveal a highly asymmetric complex, with a Perrin shape parameter of 1.23, which could correspond to a prolate ellipsoid with a major axis of about five and a minor axis of about one. We identified 12 residues, five prior to and seven following the partial domain helix in Spalpha that moved freely relative to the structural domain in the absence of Spbeta but when in the complex moved with a mobility similar to that of the structural domain. Thus, it appears that the association with Spbeta induced an unstructured-to-helical conformational transition in these residues to produce a rigid and asymmetric complex. Our findings may provide insight toward understanding different association affinities of alphabeta-spectrin at the tetramerization site for erythroid and non-erythroid spectrin and a possible mechanism to understand some of the clinical mutations, such as L49F of alpha-spectrin, which occur outside the functional partial domain region.</P>

Effect of Re and Withdrawal Rate on the Solidification Behavior of Single Crystal Superalloy AM3 (초)

( Long Fei ),( T. Jin ),( Y. S. Yoo ),( S. M. Seo ),( M. G. Lee ),( C. Y. Jo ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 대한금속재료학회 학술대회 개요집 Vol.2007 No.1

A New Joint Packet Scheduling/Admission Control Framework for Multi-Service Wireless Networks

Long Fei,Feng Gang,Tang Junhua The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.4

Quality of service (QoS) provision is an important and indispensable function for multi-service wireless networks. In this paper, we present a new scheduling/admission control frame­work, including an efficient rate-guaranteed opportunistic scheduling (ROS) scheme and a coordinated admission control (ROS­CAC) policy to support statistic QoS guarantee in multi-service wireless networks. Based on our proposed mathematical model, we derive the probability distribution function (PDF) of queue length under ROS and deduce the packet loss rate (PLR) for individual flows. The new admission control policy makes admission decision for a new incoming flow to ensure that the PLR requirements of all flows (including the new flow) are satisfied. The numerical results based on ns-2 simulations demonstrate the effectiveness of the new joint packet scheduling/admission control framework.

DRA0336, Another OxyR Homolog, Involved in the Antioxidation Mechanisms in Deinococcus radiodurans

Longfei Yin,Liangyan Wang,Huiming Lu,Guangzhi Xu,Hongdan Zhan,Bing Tian,Yuejin Hua,Huan Chen 한국미생물학회 2010 The journal of microbiology Vol.48 No.4

A novel OxyR (DR0615) with one conserved cysteine that senses hydrogen peroxide in Deinococcus radiodurans had been identified in our previous work. Comparative genomics revealed that D. radiodurans possesses another OxyR homolog, OxyR2 (DRA0336). In this study, we constructed the deletion mutant of oxyR2 and the double mutant of both the OxyR homologs to investigate the role of OxyR in response to oxidative stress in D. radiodurans. Deletion of oxyR2 resulted in an obviously increased sensitivity to hydrogen peroxide, and the double mutant for oxyR and oxyR2 was significantly more sensitive than any of the two single mutants. The total catalase activity of the double mutant was lower than that of any of the single mutants, and reactive oxygen species (ROS) accumulated to a greater extent. DNA microarray analysis further suggested that oxyR2 was involved in antioxidation mechanisms. Site-direct mutagenesis and complementation analysis revealed that C228 in OxyR2 was essential. This is the first report of the presence of two OxyR in one organism. These results suggest that D. radiodurans OxyR and OxyR2 function together to protect the cell against oxidative stress.

Mobile Anchor Assisted Distributed Localization for Wireless Sensor Networks with Holes

Longfei Wen,Fenxi Yao,Guang Ye,Lingguo Cui,Baihai Zhang 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Location information of sensor node is very significant in wireless sensor networks (WSNs). Currently, localization approaches can be divided into two categories: distributed and centralized. Due to the requirement of the flexibility and real-time performance, distributed algorithms reveal huge advantage. DV-Hop is a classical distributed one which works by transforming the distances to all anchors from hops to units of length measurement (e.g., meters, feet) using the average size of a hop. In anisotropic networks with holes, the performance of DV-Hop degrades because of the imprecise estimation of the hop count and average size of a hop. In this work, a mobile anchor assisted distributed localization method (MAA-DL) is proposed which can decrease the impact of holes in sensor networks. The proposed method uses some mobile anchors to mark some nodes on the boundary of the holes to refine the distances to the anchors. Simulation results show that the proposed algorithm is adapted to anisotropic networks in different situations when varying the node scale and anchor scale. The localization error can be largely decreased using MAA-DL in networks with convex or concave holes.

Calendar and Astrology in Early Qing China : A Distinctive Way of Integration: The Main Portion of Xue Fengzuo`s Lixue huitong Revisited

( Longfei Chu ) 한국과학사학회 2015 한국과학사학회지 Vol.37 No.2

In his voluminous collectanea Lixue huitong 曆學會通 (An Integration of Calendri-cal Learning), the famous astronomer and mathematician, Xue Fengzuo 薛鳳祚, tried to integrate different systems of calendrical astronomy, both Chinese and Western, ancient and recent. The result of his integration is the “New Chinese Method” (xin zhongfa 新中法) in the Main Portion of the Lixue huitong. Three aspects in Xue Fengzuo’s integrating work attract our attention. First of all, his “New Chinese Method” is an integration of the four major systems: the Shoushi li 授時曆, the Huihui li 回回曆, the Chongzhen lishu 崇禎曆書, and the astronomical part of the Tianbu zhenyuan 天步眞原. Secondly, in the “New Chinese Method”, Xue Fengzuo makes as many adjustments as possible to make the system “Chinese.” Finally, he adds the procedures needed in the calculation of the astrological notes (lizhu 曆注) in the almanac and other astrological applications. In fact, Xue Fengzuo’s integration had close connection with the age he lived, and his distinctive way of integration is a response to the dissemination of European astronomy and astrology in China.

Development of a Mechanistic Cutting Force Model for Micro Drilling Process

Longfei Hu,Dae Hoon Kim,Sang Won Lee 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.6

Multi-objective optimization model of high-temperature ceramic filter

Longfei Liu,Zhongli Ji,Xin Luan 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.5

Ceramic filters have been widely used in industrial engineering, such as the Shell coal gasification process (SCGP) and Integrated gasification combined cycle (IGCC), where the performance of the ceramic filter is achieved by the pulse jet. Residual pressure drop and gas consumption are directly related to reverse-flow pulse (RFP) pressure. However, in the process of operation, the RFP pressure is too large and gas consumption is too high. In this study, the effects of RFP pressures on filter’s cleaning efficiency, residual pressure drop, and gas consumption were investigated on a ceramic filter. Within a certain range, the cleaning efficiency gradually increased with increased RFP pressure. When the RFP pressure reached a certain value, the cleaning efficiency did not increase with increased pressure, showing a quadratic relationship between cleaning efficiency and RFP pressure. The residual pressure drop and RFP pressure were also in a quadratic relationship. Besides, the gas consumption increased linearly as increased RFP pressure according to the theoretical model. Based on the research results, a multi-objective optimization model of a ceramic filter was established with the cleaning efficiency as a constraint condition, gas consumption and residual pressure drop as the optimization objectives. A fuzzy decision-making method was used to solve the optimization model and calculate the residual pressure drop and gas consumption, from which the optimal RFP pressure was obtained.

Real-time life and degradation prediction of ceramic filter tube based on state-space model

Liu Longfei 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10

Bayesian estimation theory was used in this study to establish a state-space model of the ceramic filter tube degradation process. The model continuously integrates the latest residual pressure drop to update its own parameters, then the change rate of the degradation state, remaining life, and failure probability density distribution of the tube in real time. The residual pressure drop of the Shell Coal Gas Process was analyzed to find that the model results converge to real values as the residual pressure drop increases. The change rate of the ceramic filter tube degradation state calculated by the model gradually decreases over time, which is consistent with the initial rapid increase in residual pressure drop followed by a slower increase in later stages of operation. The amount of particle deposition in the ceramic filter tube wall under different operating times was measured and predicted; the predictions are consistent with the state-space model results. The state-space model also reflects variations in filter tube performance degradation caused by emergent conditions such as leakage or fractures, as it does not make stationarity assumptions for the degradation process.

Regulating Countermeasures Research on Marine Environmental Pollution from Ships in the Background of Arctic Navigation

Li Longfei 원광대학교 한중관계연구원 2021 韓中關係硏究 Vol.7 No.2

최근 지구온난화로 북극해 통항이 현실화되면서 북극해 항로를 운항하는 선박의 수 가 지속적으로 증가하고 있으며, 이로 인한 북극해양환경이 선박오염문제로 날로 심각 해져 국제적 관심이 쏠리고 있다. 이처럼 북극해를 운항하는 선박으로 인해 발생하는 해양오염문제는 북극환경에 일련의 부정적인 영향을 미치게 된다. 즉, 북극해를 운항 하는 선박수의 증가로 인해 북극빙하의 녹는 속도가 빨라질 뿐만 아니라, 선박에서 투기된 폐기물로 인해 해양생태환경도 큰 위협이 되고 있다. 이처럼 북극해 통항과 북극해양환경에 대한 기존의 규정으로는 북극해양환경보호 를 규정하는 「유엔해양법협약(UNCLOS)」, 페기물이나 다른 물질의 투기를 규제하는 해양오염 방지조약인 「런던협약(London Dumping Convention)」, 선박의 기름, 유해 액체 물질, 포장 유해물질, 하수, 쓰레기 및 대기오염물질 따위를 규제하고 있는 「국제해양 오염방지협약(MARPOL)」 등이 북극해양환경이나 선박오염의 규제에 중요한 역할하고 있다고는 하지만, 규제의 한계로 인하여 국제사회는 새로운 방안을 모색하고 있다. 또한, 한국과 중국도 북극해양 환경호보와 정비사업에 적극적으로 참여하여 북극해 양과학 답사와 연구를 부단히 강화하고 있다. 또 북극해양환경에 대한 모니터링 및 조기경보를 강화하여 북극지역 해양환경 개선에 힘쓰고 있다. 이는 양국이 북극해양 환경보호라는 공통된 당면과제를 해결하기 위해 협력관계를 유지하고 있다는 점에 의 의가 있을 것이다. 이에 본 연구에서는 선박의 북극통항으로 인한 북극해양 환경변화에 대한 분석을 통해 북극의 선박오염과 관련한 법률규정 및 그 문제점을 명확히 하였다. 또 북극통항 의 선박오염에 대한 대응책을 마련하여 지속가능한 발전을 추진할 수 있는 방안을 제 시하였다. Arctic Passage has already had its realistic foundation due to the global warming, and pollution from ships in Arctic marine environment are emerging with the increasing number of ships in Arctic Passage. Series of negative impacts were caused by Arctic Navigation, such as the increasing number of ships can accelerate the melting speed of Arctic sea ice, wastes dumped from ships could pose extreme threat on marine ecological environment, and oil pollution from ships might also play irreversible destruction impact on Arctic marine environment. Hereby to put forward the corresponding measures from international and China footing through classifying the protection and shortages on Arctic marine environment of United Nations Convention on the Law of the Sea, the regulating countermeasures and deficiencies on wastes dumped form ships of Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matters, and the measures and shortages on oil pollution form ships of International Convention for the Prevention of Pollution from Ships. In international level, both the laws and policy practices of the surround Arctic nations and the development of International Maritime Organization have remarkable progresses on the protection of Arctic marine environment; In China level, related laws and policies practices contribute China to make remarkable progresses on Arctic marine protection, but also with certain problems, so to strengthen the scientific expenditures and researches in Arctic marine, enhance the supervision and warning of Arctic marine environment, actively participate in the treatment of Arctic marine environment, and enlarge the international cooperation on Arctic marine environment have great significance on the protection and treatment of pollution from ships in Arctic marine environment. Countries around the Arctic have played important role in the pollution treatment of Arctic marine environment. As the responsible countries, China and South Korea are also actively participating the pollution protection works on Arctic marine environment. National policies and countermeasures of different countries in Arctic marine environment are favorable to the international cooperation on Arctic marine environmental protection, the union of friendship among countries, and the sustainable development of Arctic marine environment.