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Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems
Engel, Gregory S.,Calhoun, Tessa R.,Read, Elizabeth L.,Ahn, Tae-Kyu,Manč,al, Tomá,š,Cheng, Yuan-Chung,Blankenship, Robert E.,Fleming, Graham R. Nature Publishing Group 2007 Nature Vol.446 No.7137
Photosynthetic complexes are exquisitely tuned to capture solar light efficiently, and then transmit the excitation energy to reaction centres, where long term energy storage is initiated. The energy transfer mechanism is often described by semiclassical models that invoke ‘hopping’ of excited-state populations along discrete energy levels. Two-dimensional Fourier transform electronic spectroscopy has mapped these energy levels and their coupling in the Fenna–Matthews–Olson (FMO) bacteriochlorophyll complex, which is found in green sulphur bacteria and acts as an energy ‘wire’ connecting a large peripheral light-harvesting antenna, the chlorosome, to the reaction centre. The spectroscopic data clearly document the dependence of the dominant energy transport pathways on the spatial properties of the excited-state wavefunctions of the whole bacteriochlorophyll complex. But the intricate dynamics of quantum coherence, which has no classical analogue, was largely neglected in the analyses—even though electronic energy transfer involving oscillatory populations of donors and acceptors was first discussed more than 70 years ago, and electronic quantum beats arising from quantum coherence in photosynthetic complexes have been predicted and indirectly observed. Here we extend previous two-dimensional electronic spectroscopy investigations of the FMO bacteriochlorophyll complex, and obtain direct evidence for remarkably long-lived electronic quantum coherence playing an important part in energy transfer processes within this system. The quantum coherence manifests itself in characteristic, directly observable quantum beating signals among the excitons within the Chlorobium tepidum FMO complex at 77 K. This wavelike characteristic of the energy transfer within the photosynthetic complex can explain its extreme efficiency, in that it allows the complexes to sample vast areas of phase space to find the most efficient path.
Aloia, Gregory F.,Rhee, Kun Min,Bakken, Jeffrey P.,Chaudhari, Ramesh,Chung, Yong Suk 大邱大學校 障碍人綜合硏究所 1997 再活科學硏究 Vol.13 No.1
이 연구의 목적은 이전의 비효율적인 교수법으로 학생들을 지도했던 교사들에게 새로운 교원양성 프로그램을 교육시켜 학생들에게 보다 더 효과적인 지도를 하고자 하는 데 있다. 여기의 새로운 교원양성 프로그램은 공학을 교육에 접목시키는 과정과 관련된 세가지 영역을 설명하게 될 것이다. 첫째로 역사적 관점에서 오늘날의 학교가 효율적인 공학적 변화에 있어서 가지고 있는 네가지 제한점을 말하고 있으며, 둘째로 바람직한 공학적 변화를 실현시키고자 할 때 고려해야 할 주의 사항을 설명하고 있다. 마지막으로는 공학적 변화를 위한 교원양성모형을 제시하고 있다. 첫 번째의 역사적 관점에서 오늘날의 학교가 가진 제한점은 비효율적 변화의 유산과 전문교원의 재훈련, 장기공약, 자원을 뒷받침하는 공약으로 설명하고 있으며, 두 번째의 바람직한 공학적 변화를 실현시키고자 할 때 고려할 점은 공학을 둘러싸고 있는 변화의 기본적인 성질을 이해하는 것과 그것이 아주 근본적인 변화라는 사실은 변화의 적절성 및 중요성을 교원들에게 인식시켜야 할 필요성을 증대시키는 것이다. 세 번째인 교원양성 프로그램은 교사행동 변화를 위한 모든 시도에서 적절하고, 지속적이고, 지원적이며 철저해야 한다는 네 가지 전제하에서 MIRACLE 이란 7단계 교원양성모형을 소개한다: 1단계 인식수준-전략에의 친밀감, 2단계 전략의 이해-전후관계, 최대/최소 적용 가능한 조건들, 3단계 전문가 양성환경에서 동료와 함께 시도할 수 있는 기회에 대한 시뮬레이션, 4단계 실습-실제학습에 시연할 기회, 5단계 일상적 수업목록으로의 전환, 6단계 급작스런 문제 대처를 위한 "믿을 만한 전문가"와의 도움, 7단계 기능의 지속 및 정기적인 재정비와 다듬는 것으로 설명하고 있다. This paper will address three areas relevant to the process of incorporating technology in education. The first will identify four historic limitations to a school's ability to implement effective changes in technology. The second addresses several caveats that must be considered if the desired technological changes are to be realized. The third presents a model of staff development to implement the changes in technology.
Overexpression of Ornithine Decarboxylase Suppresses Thapsigargin-Induced Apoptosis
Wei-Chung Hsieh,Pei-Chen Hsu,Ya-Fan Liao,Shu-Ting Young,Zeng-Wei Wang,Chih-Li Lin,Gregory J. Tsay,Huei Lee,Hui-Chih Hung,Guang-Yaw Liu 한국분자세포생물학회 2010 Molecules and cells Vol.30 No.4
Ornithine decarboxylase (ODC), the key enzyme of poly-amine biosynthesis, has paradoxical roles in apoptosis. Our published papers show overexpression of ODC pre-vents the apoptosis induced by many cytotoxic drugs. Thapsigargin (TG) is an inhibitor of the sarcoplasmic/en-doplasmic reticulum (ER) Ca2+ ATPase (SERCA) pumps and causes ER stress-induced apoptosis. We used ODC overexpressing cell lines to examine whether overexpres-sion of ODC inhibits TG-induced apoptosis. Our results indicated overexpression of ODC attenuated TG-induced apoptosis. Overexpression of ODC blocked procaspse-4 cleavage and phosphorylation of protein kinase-like ER-resident kinase (PERK), triggered by TG. It also attenuated the increase in CAAT/enhancer binding protein homolo-gous protein (CHOP). Cells with overexpressed ODC had greater Bcl-2 expression. Overexpression of ODC pre-served the expression of Bcl-2, inhibited the increase in Bak and stabilized mitochondrial membrane potential without the influences of TG. Cytochrome c release and downstream caspase activation were blocked. That is, overexpression of ODC inhibits the mitochondria-medi-ated apoptotic pathway, induced by TG. Finally, overex-pression of ODC maintains the protein and mRNA expres-sion of SERCA. In conclusion, overexpression of ODC suppresses TG-induced apoptosis by blocking caspase-4 activation and PERK phosphorylation, attenuating CHOP expression and inhibiting the mitochondria-mediated apoptotic pathway.
Overexpression of Ornithine Decarboxylase Suppresses Thapsigargin-Induced Apoptosis
Hsieh, Wei-Chung,Hsu, Pei-Chen,Liao, Ya-Fan,Young, Shu-Ting,Wang, Zeng-Wei,Lin, Chih-Li,Tsay, Gregory J.,Lee, Huei,Hung, Hui-Chih,Liu, Guang-Yaw Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.30 No.4
Ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis, has paradoxical roles in apoptosis. Our published papers show overexpression of ODC prevents the apoptosis induced by many cytotoxic drugs. Thapsigargin (TG) is an inhibitor of the sarcoplasmic/endoplasmic reticulum (ER) $Ca^{2+}$ ATPase (SERCA) pumps and causes ER stress-induced apoptosis. We used ODC overexpressing cell lines to examine whether overexpression of ODC inhibits TG-induced apoptosis. Our results indicated overexpression of ODC attenuated TG-induced apoptosis. Overexpression of ODC blocked procaspse-4 cleavage and phosphorylation of protein kinase-like ER-resident kinase (PERK), triggered by TG. It also attenuated the increase in CAAT/enhancer binding protein homologous protein (CHOP). Cells with overexpressed ODC had greater Bcl-2 expression. Overexpression of ODC preserved the expression of Bcl-2, inhibited the increase in Bak and stabilized mitochondrial membrane potential without the influences of TG. Cytochrome c release and downstream caspase activation were blocked. That is, overexpression of ODC inhibits the mitochondria-mediated apoptotic pathway, induced by TG. Finally, overexpression of ODC maintains the protein and mRNA expression of SERCA. In conclusion, overexpression of ODC suppresses TG-induced apoptosis by blocking caspase-4 activation and PERK phosphorylation, attenuating CHOP expression and inhibiting the mitochondria-mediated apoptotic pathway.
Coronary Artery Dose-Volume Parameters Predict Risk of Calcification After Radiation Therapy
Sarah A. Milgrom,Bibin Varghese,Gregory W. Gladish,Andrew D. Choi,Wenli Dong,Zarana S. Patel,Caroline C. Chung,Arvind Rao,Chelsea C. Pinnix,Jillian R. Gunther,Bouthaina S. Dabaja,Steven H. Lin,Karen E 한국심초음파학회 2019 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.27 No.4
BACKGROUND: Radiation exposure increases the risk of coronary artery disease (CAD). We explored the association of CAD with coronary artery dose-volume parameters in patients treated with 3D-planned radiation therapy (RT). METHODS: Patients who received thoracic RT and were evaluated by cardiac computed tomography ≥ 1 year later were included. Demographic data and cardiac risk factors were retrospectively collected. Dosimetric data (mean heart dose, dmax, dmean, V50 - V5) were collected for the whole heart and for each coronary artery. A coronary artery calcium (CAC) Agatston score was calculated on a per-coronary basis and as a total score. Multivariable generalized linear mixed models were generated. The predicted probabilities were used for receiver operating characteristic analyses. RESULTS: Twenty patients with a median age of 53 years at the time of RT were included. Nine patients (45%) had ≥ 3/6 conventional cardiac risk factors. Patients received RT for breast cancer (10, 50%), lung cancer (6, 30%), or lymphoma/myeloma (4, 20%) with a median dose of 60 Gy. CAC scans were performed a median of 32 months after RT. CAC score was significantly associated with radiation dose and presence of diabetes. In a multivariable model adjusted for diabetes, segmental coronary artery dosimetric parameters (dmax, dmean, V50, V40 V30, V20, V10, and V5) were significantly associated with CAC score > 0. V50 had the highest area under the ROC curve (0.89, 95% confidence interval, 0.80-0.97). CONCLUSIONS: Coronary artery radiation exposure is strongly correlated with subsequent segmental CAC score. Coronary calcification may occur soon after RT and in individuals with conventional cardiac risk factors.
Flight Test Measurement and Assessment of a Flapping Micro Air Vehicle
Jong Heon Kim,Chan Yik Park,Seungmoon Jun,Dae Keun Chung,Jong Rok Kim,Hee Chul Hwang,Bret Stanford,Philip Beran,Gregory Parker,Denny Mrozinski 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.2
Flight test of flapping micro air vehicles (FMAVs) is carried out using an instrumented measurement system to obtain various engineering parameters and hence to assess the flight performance of the vehicles through the data investigation. An indoor flight test facility equipped with a motion capture system and tracking cameras is used for the work presented in this paper. Maneuvers including straight-level flight, ground flapping, takeoff and landing are tested. Spatial position and orientation data are obtained from the retro-reflective tracking markers attached to the vehicles. Subsequent test analysis is carried out by generating performance parameters from raw data and then assessing the flight performance by comparison of the vehicles. The main findings of this work confirm that the test method and procedures presented here enable the systematic numerical data measurement and assessment of the flying performances of these vehicles, and show the applicability for the test and evaluation of general flapping MAVs.
Screening of Myxobacteria Carrying Tubulysin Biosynthetic Genes
( Hyesook Hyun ),( Juo Choi ),( Daun Kang ),( Yungpil Kim ),( Pilgoo Lee ),( Gregory J. Y. Chung ),( Kyungyun Cho ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 한국미생물·생명공학회지 Vol.49 No.1
Tubulysins are a group of secondary metabolites produced by myxobacteria that inhibit the function of the eukayotic cytoskeleton. We developed a pair of PCR primers that specifically amplified tubulysin biosynthetic genes. Using these primers, eight out of the eighty-one strains of myxobacteria belonging to the Cystobacteraceae family that harbored putative tubulysin biosynthetic genes were screened through PCR analysis. The selected strains included two Archangium gephyra, two Stigmatella sp., two Vitiosangium cumulatum, and two unidentified myxobacteria. LC-MS analysis of the culture extracts from the selected strains revealed that A. gephyra KYC4066 produced putative tubulysin A and B.
( Juo Choi ),( Taejoon Park ),( Daun Kang ),( Jeongju Lee ),( Yungpil Kim ),( Pilgoo Lee ),( Gregory J. Y. Chung ),( Kyungyun Cho ) 한국미생물 · 생명공학회 2021 한국미생물·생명공학회지 Vol.49 No.4
Argyrins are a group of anticancer and antibacterial octapeptide bioactive substances isolated from myxobacteria. In this study, we showed that the myxobacterium Archangium gephyra MEHO_001, isolated in Korea, produces argyrins A and B. MEHO_001 cells tend to aggregate when cultured in liquid media. Hence, a dispersion mutant, MEHO_002, was isolated from MEHO_001. The MEHO_002 strain produced approximately 3.5 times more argyrins than that produced by the wild-type strain MEHO_001. We determined the whole-genome sequence of A. gephyra MEHO_002 and identified a putative argyrin biosynthetic gene cluster comprising five genes, arg1-arg5, encoding non-ribosomal peptide synthases and tailoring enzymes. Inactivation of arg2 by plasmid insertion disrupted argyrin production. The amino acid sequences of the proteins encoded by arg2-arg5 of A. gephyra MEHO_002 were 90-98% similar to those encoded by the argyrin biosynthetic genes of Cystobacter sp. SBCb004, an argyrin-producing myxobacterium with identical domain organization.