Contrast enhanced microscopy

To sunimarize, using EMSI and contrast enhanced microscopy we succeeded to visualize both the oxide film damage and the nucleation and... 

B1.18.5.5 CONTRAST ENHANCEMENT AND PRACTICAL LIMITS TO CONFOCAL ONE-PHOTON-EXCITATION FLUORESCENCE MICROSCOPY... 

Figure 1.1 is a rather remarkable photograph which shows individual polystyrene molecules as spherical blobs having average diameters of about 20 nm. The picture is an electron micrograph in which a 10" % solution of polystyrene was deposited on a suitable substrate, the solvent evaporated, and the contrast enhanced by shadow casting. There is a brief discussion of both electron microscopy and shadowing in Sec. 4.7. Several points should be noted in connection with Fig. 1.1 ...

Rees JA, Old SL, Rowlands PC. An ultrastructural histochemistry and light microscopy study of the early development of renal proximal tubular vacuolation after a single administration of the contrast enhancement medium lotrolan . Toxicol Pathol 1997 25 158-164. 

Fig. 4. CHO cells on a microcarrier a optical microscopy (contrast enhancement by Crystal Violet staining) and b scanning electron microscopy...

In the following summary of contrast enhancement techniques, it is assumed that specimens are being observed in transmission, that they are not self-luminous, and that the light source is not imaged onto the specimen by the microscope condenser. All these assumptions describe typical conditions for LCP microscopy. Figures 5 and 6 show ray diagrams for a normally incident and obliquely incident beam of parallel rays, respectively. In both cases, the objective back focal plane contains the Fraunhofer diffraction pattern of the specimen. 

At this point it is worth comparing the different techniques of contrast enhancements discussed so far. They represent spatial filtering techniques which mostly affect the zeroth order dark field microscopy, which eliminates the zeroth order, the Schlieren method (not discussed here), which suppresses the zeroth order and one side band and, finally, phase contrast microscopy,where the phase of the zeroth order is shifted by ti/2 and its intensity is attenuated. 

Vesely and Finch used two radiation effects for contrast enhancement of the samples, which were examined by scanning transmission electron microscopy (i) differential formation of double bonds (through reactions such as (R-13)) in a component polymer, and (ii) differential mass... 

I. Contrast Enhancement of Dispersed Nuclear Material on the EM Grid j. Electron Microscopy... 

Specimen preparation may be broadly classified into two main areas specimen preparation techniques for transmitted-light microscopy (thin sections, smears, fibers, particulate strews) and specimen preparation techniques for reflected-light microscopy (surface preparation of opaque and nearly opaque materials). However, they are by no means exclusive and, although metals, ores, and opaque minerals may be studied by reflected light only, thin sections, smears, etc., may be studied both by transmitted and by reflected light, e.g., transmitted-light and epifluorescence microscopy. The advantages of such dual observational techniques relate in particular to contrast enhancement (criterion (3)). 

Contrast enhancement by deposition of a metal oxide, sulfide, selenide, etc., film is a relatively new technique (interference film microscopy) and also lends itself to quantitative interpretation. 

Optical Microscopy. Traditionally, light microscopy has played an important role in the visualization of ordered polymers, and a range of different approaches can be adopted to enhance the contrast, phase contrast, polarized light microscopy, orientation birefringence, strain birefringence, modnlated contrast, interference microscopy, etc (132,141-144). Light microscopy rarely provides resolution better than several micrometers bnt can give a quick and easy assessment of the extent of order in the polymer material. 

An additional problem associated with the direct investigation of polymeric materials by electron microscopy is in the usually low contrast between structural details. In connection with deformation, the effect of straining-induced contrast enhancement is of particular importance. Structural elements, such as particles, which possess a smaller Young s modulus than the surroimding material, show a preferred extensibility or deformation during stretching of the sample. In the direction of the electron beam, the thickness of the sample decreases at these places, thus causing a difference in the intensity of the transmitted electron beam and an enhanced contrast (2,10). 

In all other cases, the internal polymer structure must be developed to produce a surface topography visible with a good contrast in EM. Etching for contrast enhancement in polymer microscopy includes the removal of one or more components (or phases ) of the polymer by physical or chemical means. In most cases, the constituents of a heterogeneous polymer system are more or less sensitive to a certain treatment. Etching procedures can be applied to the original sample surface as well as to block faces smoothed by a microtome or fracture surfaces. 

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