1.

일시 : 2015년 12월 3일(목) 오후 5:00

장소 : 아산이학관 331호

연사 : 심상희 교수(울산과학기술원 화학과)

제목 : Super-resolution Optical Microscopy of Living Cells

Abstract: 

Super-resolution fluorescence microscopy has overcome the diffraction limit of optical microscopes over an order of magnitude and open new windows for visualizing ultrastructural dynamics in vivo. One major group of such methods utilizes photoswitching probes for separating fluorophores in time, thereby localizing single molecules at high precision. This group was first introduced by the names of STORM (stochastic optical reconstruction microscopy) and PALM (photoactivated localization microscopy). 

Here, I will present various STORM imaging methods for living cells. Proteins in live cells were imaged with photoswitchable cyanine dyes whose brightness and fast switching enabled 3D resolutions of 30-50 nm within 1-2 seconds. Membranes in live cells were stained with small-molecule probes that allowed us to resolve previously obscured details on dynamics of the plasma membrane, the endoplasmic recticulum (ER) and mitochondria. 

Fluorescence microscopy faces intrinsic resolution limit set by the size of fluorescent probe. In order to overcome the label-limited resolution, I propose ways to surpass the resolution of Raman microscopy for achieving super-resolution optical microscopy with minimal label size.  The proposed super-resolution method may lay a stepping-stone for achieving label-free, molecular-specific, molecular-resolution imaging tool.

2.

일시 : 2015년 12월 3일(목) 오후 6:00

장소 : 아산이학관 331호

연사 : 곽경원 교수(중앙대학교 화학과)

제목 : Spectroscopic & Computational Approach to the Advanced Electrolytes.(Li+ Ion Solvation Dynamics observed with linear and nonlinear IR spectroscopy & Calculation method for oxidation potential of organic additives.)

Abstract: 

Electrolytes are ubiquitous and indispensable in all electrochemical devices including electrolytic cells, capacitors, fuel cells, or batteries. Moreover, their function is the same in devices for serving as the medium for the ion transport between electrodes.  The electrolyte determines how fast the energy could be released by controlling the rate of mass flow within the battery. After making solid electrolyte interphase on the carbonaceous anode, there is no decomposition in electrolyte and Li ion transport occurs through electrolyte. Thus, it has been suggested that the solvation structures and dynamics of Li ions in liquid electrolyte play an essential role to Li-based battery performance. 

To mimic commercial electrolyte composition composed of carbonates, Li ion were dissolved in diethylcarbonate (DEC) and its solvation behavior was observed with IR spectroscopy as well as time-resolved IR spectroscopies including IR pump-probe and 2D-IR experiments. IR spectroscopic results combined with DFT study reveals the possible solvation structure and major interaction site for Li ion. Subsequent 2D-IR experiments show that there is fast equilibrium solvation dynamics around Li-ion, which might give some clues about the molecular mechanism of Li ion transport through electrolyte.  

One of the main challenges for the advanced battery system is developing suitable electrolyte materials. The first requirement for suitable electrolytes is the stability within the electrochemical window of the battery. Thus, electrolyte molecules or additives have to be resistant to the reduction or oxidation during the cell operation. As another research topic, computational method combined with experiment will be presented to predict oxidation potential of organic molecules, which will enable High-Throughput screening for accelerating electrolyte discovery. 

20151203_특별세미나_심상희교수.hwp

20151203_특별세미나_곽경원교수.hwp