Measurement is the key to understanding. Scientific discoveries can always be expected from the development of measurement science and technology. I am interested in the development of novel methods, tools, and instruments in any area where precise measurement is desired, especially the life sciences which are full of challenges and beauties. In Janelia, I am working on Bessel beam plane illumination microscopy for live-cell imaging and presumably for embryology, neurobiology, and many other areas of biology. The goal is to push the spatial and temporal resolution of fluorescence microscopy with minimum photobleaching, phototoxicity, and photodamage.
A key challenge when imaging living cells is how to noninvasively extract the most spatiotemporal information possible. Unlike popular wide-field and confocal methods, plane-illumination microscopy limits excitation to the information-rich vicinity of the focal plane, providing effective optical sectioning and high speed while minimizing out-of-focus background and premature photobleaching. Here we used scanned Bessel beams in conjunction with structured illumination and/or two-photon excitation to create thinner light sheets (<0.5 μm) better suited to three-dimensional (3D) subcellular imaging. As demonstrated by imaging the dynamics of mitochondria, filopodia, membrane ruffles, intracellular vesicles and mitotic chromosomes in live cells, the microscope currently offers 3D isotropic resolution down to ∼0.3 μm, speeds up to nearly 200 image planes per second and the ability to noninvasively acquire hundreds of 3D data volumes from single living cells encompassing tens of thousands of image frames.
Axial CID and high pressure resonance CID in a miniature ion trap mass spectrometer using a discontinuous atmospheric pressure interface.Journal of the American Society for Mass Spectrometry 2010
L. Gao, G. Li, and G. R. Cooks Journal of the American Society for Mass Spectrometry, 21:209-14 (2010)
Axial collision induced dissociation (CID) and high-pressure resonance CID were implemented and compared with normal low-pressure resonance CID in a miniature ion trap mass spectrometer to obtain more complete fragmentation spectra. Axial CID was realized simply by applying a potential to the discontinuous atmospheric pressure interface (DAPI) capillary without performing parent ion isolation before dissociation. High-pressure resonance CID employed a double-introduction pulse scan function, by means of which precursor ions isolated at low-pressure (<10(-3) torr) were dissociated at high-pressure (0.1 torr-1 torr) with higher excitation energy, so that tandem MS of isolated precursor ions was achieved and extensive fragmentation was obtained. A simple peptide (Leu-enkephalin) and dye molecule (rhodamine B) ionized by ESI were used to investigate both methods and compare them with normal low-pressure resonance CID.