Selectivity microscopy

Fig. 3. Experimental demonstration of two-photon selective microscopy. The HPTS-labeled sample being imaged has acidic (bottom side) and a basic (top side) regions. Images were obtained with (A) 23-fs transform-limited pulses centered at 842 nm, and (B and C) phase shaped pulses optimized for selective excitation.

FIGURE 36 Molecular selective microscopy using coherent anti-Stokes Raman scattering, (a) On-resonant picture of deuter-ated and nondeuterated liposomes with two liposomes visible are shown. Only the deuterated liposomes have a Raman resonance for the radiation used, (b) The same picture as that in (a), but the two pump waves have been detuned from the Raman resonance. (c) The nonresonant signal has been subtracted from the resonant one, leaving only the deuterated liposome visible. [Reproduced from Duncan, M. D. (1984). Opt. Comm. 50, 307. Copyright North-Holland, Amsterdam.]... 

Micellar structure has been a subject of much discussion [104]. Early proposals for spherical [159] and lamellar [160] micelles may both have merit. A schematic of a spherical micelle and a unilamellar vesicle is shown in Fig. Xni-11. In addition to the most common spherical micelles, scattering and microscopy experiments have shown the existence of rodlike [161, 162], disklike [163], threadlike [132] and even quadmple-helix [164] structures. Lattice models (see Fig. XIII-12) by Leermakers and Scheutjens have confirmed and characterized the properties of spherical and membrane like micelles [165]. Similar analyses exist for micelles formed by diblock copolymers in a selective solvent [166]. Other shapes proposed include ellipsoidal [167] and a sphere-to-cylinder transition [168]. Fluorescence depolarization and NMR studies both point to a rather fluid micellar core consistent with the disorder implied by Fig. Xm-12. 

Asbestos fiber identification can also be achieved through transmission or scanning electron microscopy (tern, sem) techniques which are especially usefiil with very short fibers, or with extremely small samples (see Microscopy). With appropriate peripheral instmmentation, these techniques can yield the elemental composition of the fibers using energy dispersive x-ray fluorescence, or the crystal stmcture from electron diffraction, selected area electron diffraction (saed). 

Thin films of metals, alloys and compounds of a few micrometres diickness, which play an important part in microelectronics, can be prepared by die condensation of atomic species on an inert substrate from a gaseous phase. The source of die atoms is, in die simplest circumstances, a sample of die collision-free evaporated beam originating from an elemental substance, or a number of elementary substances, which is formed in vacuum. The condensing surface is selected and held at a pre-determined temperature, so as to affect die crystallographic form of die condensate. If diis surface is at room teiiiperamre, a polycrystalline film is usually formed. As die temperature of die surface is increased die deposit crystal size increases, and can be made practically monocrystalline at elevated temperatures. The degree of crystallinity which has been achieved can be determined by electron diffraction, while odier properties such as surface morphology and dislocation sttiicmre can be established by electron microscopy. 

Transmission Electron Microscopy Transmission Electron Microscope Conventional Transmission Electron Microscopy Scannir Transmission Electron Microscopy High Resolution Transmission Electron Microscopy Selected Area Diffraction Analytical Elearon Microscopy Convergent Beam Elearon DifFraaion Lorentz Transmission Electron Microscopy... 

The screening of libraries of compounds for the desired property constitutes an essential part of the combinatorial process. The easier and the faster the screening, the higher the throughput and the more compounds can be screened in a unit of time. This paradigm has led Still s group to develop a combinatorial approach to chiral selectors that involves a visual screening step by optical microscopy that enables the manual selection of the best candidates [81]. 

The FTIR technique has also the advantage of being easily associated to other techniques. For instance, the FTIR microscopy, which couples the visible image of the samples to the corresponding infrared spectra, allows the selection of microareas of interest, and thus an easy determination of the crystalline forms corresponding to different regions, in samples in which more than one polymorph is present [103]. 

Scanning electrochemical microscopy can also be applied to study localized biological activity, as desired, for example, for in-situ characterization of biosensors (59,60). In this mode, the tip is used to probe the biological generation or consumption of electroactive species, for example, the product of an enzymatic surface reaction. The utility of potentiometric (pH-selective) tips has also been... 

Methane oxidation and partial oxidation, electrochemical promotion of, 308 dimerization, 470 reforming, 410 Methanol dehydrogenation electrochemical promotion of, 403 selectivity modification, 404 Methanol oxidation electrochemical promotion of 398 selectivity modification, 400 Microscopy... 

Scanning tunneling microscopy, STM ordered adlattices, 264 oxygen adlattices, 261 platinum, 261 sodium adlattices, 262 spillover-backspillover, 259 Self-consistent field, 269 Selectivity definition, 17... 

Electrochemistry is the basis of many important and modem applications and scientific developments such as nanoscale machining (fabrication of miniature devices with three dimensional control in the nanometer scale), electrochemistry at the atomic scale, scanning tunneling microscopy, transformation of energy in biological cells, selective electrodes for the determination of ions, and new kinds of electrochemical cells, batteries and fuel cells. 

Affinity chromatography using factor XII as ligand leads to purification of u-PAR rather selectively, with only trace quantities of cytokeratin 1 or gClqR present [K. Joseph and A. Kaplan, unpubl. observations]. It is of interest that none of these three proteins possesses a transmembrane domain but u-PAR has a phos-phatidylinositol linkage within the cell membrane. Nevertheless, each of them has been isolated from purified cell membranes and they have been demonstrated to exist within the cell membrane by immunoelectron microscopy [41] presumably... 

Microscopy methods based on nonlinear optical phenomena that provide chemical information are a recent development. Infrared snm-frequency microscopy has been demonstrated for LB films of arachidic acid, allowing for surface-specific imaging of the lateral distribution of a selected vibrational mode, the asymmetric methyl stretch [60]. The method is sensitive to the snrface distribntion of the functional gronp as well as to lateral variations in the gronp environmental and conformation. Second-harmonic generation (SHG) microscopy has also been demonstrated for both spread monolayers and LB films of dye molecules [61,62]. The method images the molecular density and orientation field with optical resolution, and local qnantitative information can be extracted. 

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