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Abstract— Time-resolved fluorescence microscopy using excitation by actively mode-locked dye lasers and analysis by time-correlated single photon counting is shown to be an effective way of obtaining a high degree of spatial and temporal resolution. The imaging capabilities of the microscope make for optimal instrument response functions even with inexpensive photomultiplier tubes. Thus far limited (by the laser source) to long wavelength visible excitation, the excellent light collection and imaging, coupled with the sensitivity of single photon counting make it highly probable that the much weaker U-V second harmonics of the visible dyes will be useable. Certainly the potential of using the third harmonic line (355 nm) of a mode-locked c.w. Nd: YAG laser, or fundamental lines from mode-locked c.w. ion lasers as excitation sources will enhance the technique. Nevertheless, with visible-absorbing dyes only it is possible to excite such fluorochromes as chlorophylls, porphyrins, xanthenes (rose bengal, erythrosin B), phycobiliproteins, thionine dyes, ethidium bromide, and so on. Furthermore, this technique can be straightforwardly extended for polarized light measurements thereby allowing determinations of rotational diffusion of fluorochromes in cells and organelles. The extension to variable temperature situations is easy to conceive. In addition to its use for examination of cellular and sub-cellular entities, the equipment described can be profitably employed wherever spatial resolution may provide extra information, such as studies of powders and the structures of surfaces and interfaces. 相似文献
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Wm. J. Firey 《Israel Journal of Mathematics》1963,1(4):201-202
Half the vector sum of a convex body and its polar reciprocal with respect to a unit sphereE containsE. A consequence of this is: The mixed area of a plane convex body and its polar reciprocal with respect toE is minimized by circles concentric withE.
This work was supported in part by a grant from the National Science Foundation, NSF-G 19838. The author is indebted to the
referee for fruitful comments. 相似文献
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R.L. Strong B. Firey F.W. deWette J.L. Erskine 《Journal of Electron Spectroscopy and Related Phenomena》1983,29(1):187-190
High-resolution electron energy loss spectroscopy (EELS) and lattice dynamical calculations based on pair interactions are used to investigate oxygen chemisorption on Al(111). The O/Al(111) System is complicated by the simultaneous formation of an oxygen overlayer and underlayer. Oxygen atoms at overlayer and underlayer sites near the Al(111) surface produce well-defined vibrational loss peaks in EELS spectra, however, dynamical coupling between the oxygen atoms and with the host lattice cause vibrational energies to shift with overlayer and underlayer concentrations. These shifts as well as structural parameters of the O/Al(111) complex can be deduced from a slab model of the surface lattice dynamics. 相似文献
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Addition and decomposition of convex polytopes 总被引:1,自引:0,他引:1
A new addition of convex polytopes is defined and the possibility of representing each polytope as a sum of “standard” polytopes
is established
The research reported in this paper was supported in part by the National Science Foundation NSF-G 19838, and by the Air Force
Office of Scientific Research grant AF EOAR 63-63.
Lecture delivered by the second author at a symposium on Series and Geometry in Linear Spaces, held at the Hebrew University
of Jerusalem from March 16 till March 24, 1964. 相似文献
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William J. Firey 《Israel Journal of Mathematics》1976,24(3-4):274-281
A function over the convex coneK{inn}, of convex bodiesK in Euclideann-space (where addition is vector addition, positive scalar multiplication is dilatation), which is linear overK{inn}, increasing with respect to set inclusion, and zero at point bodies must be a mixed volumeV(K; đ, p−1;σ
1, …,σ
n−p). Heređ, takenp−1 times, is inK{inn} andσ
1, …,σ
n−pare pairwise orthogonal unit segments spanning the orthogonal complement of the affine hull ofđ. 相似文献
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PHOTOEXCITATION OF ZINC PHTHALOCYANINE IN MOUSE MYELOMA CELLS: THE OBSERVATION OF TRIPLET STATES BUT NOT OF SINGLET OXYGEN 总被引:1,自引:0,他引:1
P. A. Firey T. W. Jones G. Jori M. A. J. Rodgers 《Photochemistry and photobiology》1988,48(3):357-360
Abstract— Liposomes were used to deliver zinc phthalocyanine (ZnPC) to cultured mouse myeloma cells. ZnPC triplets states were observed when such systems were photoexcited. Singlet oxygen luminescence was not observed in cellular media. Solutions of ZnPC in various organic solvents, sodium dodecyl sulfate micelles and dipalmitoyl phosphatidyl choline liposomes were also prepared, and time-resolved triplet state parameters and singlet oxygen production were measured for these systems to provide comparisons for the cellular suspensions. 相似文献
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