14:00〜14:45 Andrey Lomov （VBL招へい外国人研究員）
" Investigation of semiconductor porous layers
by high resolution x-ray diffractometry and reflectometry "
14:45〜15:30 Nikolai Sokolov （VBL招へい外国人研究員）
"Cobalt nanoparticles on fluoride surfaces:
MBE-growth, structure and magnetic properties"
CELL ELECTROPORATION: A NEW TECHNOLOGY FOR EMERGING BIOTECHNOLOGICAL AND THERAPEUTIC APPLICATIONS
K.P. MISHRA
Director
United Research Center
United Institute of Technology, Allahabad, 211010, India & Ex Radiation Biology Biology and Health Sciences Division
Bhabha Atomic Research Centre, Mumbai 400 085
Email: mishra_kaushala@rediffmail.com mishradrkp@gmail.com
Exposure of biological cells to high intensity but short electrical pulses ( a few kV/cm, ?s duration ) has become an active area of biomedical research in the recent years. Plasma membrane of bacterial, plant and mammalian cells become transiently permeable on application of external electric field above a characteristic threshold value permitting exchange of molecules between cell interior and the surrounding. This phenomenon, popularly called electroporation, has opened many new possibilities for cell manipulation. For example, electroporation allows gaining direct access into the cell cytoplasm, transfer of gene into a variety of cells yielding efficient transformation and help achieve cell fusion for hybridoma technology. In our laboratory extensive studies have been carried out on electroporation of mammalian cells that have provided invaluable data on nature, lifetime and resealing properties of electroporated cells. Presently, molecular mechanisms of electro-permeabilization of cell are lacking. Potential of drug loaded red cells for achieving effective cancer treatment by targeted delivery of drugs appear highly promising. Our in vitro studies on Ehrlich ascites
cells have shown that at non- toxic concentrations of doxorubicin, an antitumor drug, produced substantial killing when drug treated cells were submitted to electroporation due to enhanced entry of the drug. These results have allowed designing a strategy to overcome tumor drug resistance by electroporation technology. More recent results from our laboratory have shown that tumor cells were sensitized to γ radiation effects when combined with electroporation. A highlight of the developing new approaches for cancer treatment and other biomedical applications will be outlined.
Prof. Devadasan Velmurugan (VBL invited researcher 1 Sept. 2007−29 Sept. 2007)
Centre of Advanced Study in Crystallography and Biophysics,
University of Madras, Guindy Campus, INDIA
For a better match of results between the computer modelling and wet lab experiments, Induced Fit algorithm is used in docking programs.GLIDE program of the SCHOEDINGER USA , the commertial software and MOE were used in docking studies for HDAC inhibitors towards anti-cancer drug design, Pyrrolidine analogues for anti-diabetic properties, plant and marine products towards anti-inflammatory drug design. MD studies have also been undertaken for studies of PLA2-Vitamin E complex. Results based on the above studies will be presented.Three dimensional X-ray crystal structures of some of the ligand molecules used in the above studies were from our research group.
Dr. Amit Sharma (VBL invited researcher 2 Sept. 2007−26 Sept. 2007)
INTERNATIONAL CENTER FOR GENETIC ENGINEERING & BIOTECHNOLOGY (ICGEB),
NEW DELHI, INDIA
The group aims at understanding the structural principles that govern protein-based bio-molecular interactions in malaria parasite. Structure-function studies on several important malaria parasite proteins are currently under way. Our laboratory uses multi-disciplinary techniques within modern biology, including biochemistry, bioinformatics, cell biology, parasitology and protein crystallography, to unravel the mechanism of action of important parasite proteins. Over the past few years, we have made progress in understanding various parasite proteins involved in erythrocyte invasion. We have solved crystal structures of novel proteins from each of the above stages of the parasite life cycle. We will discuss results on several such studies involving unique malaria parasite proteins.
窒化物系半導体のヘテロ成長は格子不整合系であるため結晶内部にピエゾ電界が発生し、電子と正孔の空間的分離を引き起こす。このためLEDの発光効率の低下、発光波長のシフトを招き、デバイス応用において問題となっている。そこで、近年ピエゾ電界の効果を低減可能な無極性面、半極性面の結晶成長に注目が集まってきた。我々はこれまでに加工Siを基板として用いることで、半極性面GaNの結晶成長の作製が可能であることを示してきた。半極性面をデバイスとして応用するには、ドーピング制御及びInGaNへテロ成長技術の確立が重要である。ドーピングに関しては、これまでの研究でカーボンドープによってC面では高抵抗を示すのに対し、(1-101)面ではp型伝導制御が可能であることが明らかとなっており差異が明確に現れた。またGaN/InGaNヘテロ構造では、ピエゾ電界の抑制により発光効率の向上が期待される。リンショピン大学では、光学的評価の設備が整っており、これらの試料に対して光学的な手法を用いて評価を行うことで、その物性を明らかにすることを目的として実験を行った。
まず、Cドープの試料に対して、PL、?-PL、時間分解PLにより評価を行い、自由励起子、ドナー束縛励起子及び積層欠陥からの発光を分離して観測することが可能であった。さらに、時間分解PL測定から370−373nmのDAP発光を確認することができ、Cドープに起因すると見られる発光を確認することができた。次にInGaN結晶についても同様に光学的手法による評価を行った。その結果、半極性InGaNの内部量子効率が20％以上あり室温においても高効率発光が得られた。これは転位密度が108cm-1と比較的少ないことに起因している。さらに、時間分解PLでは、InGaN発光の時定数が200ps程度と短く、波長シフトがほとんど見られないことからピエゾ電界が抑制されていることが明らかとなった。