Instrumentation video microscopes

FIG. 3 (a) Block schematic of the typical instrumentation for SECM with an amperometric UME tip. The tip position may be controlled with various micropositioners, as outlined in the text. The tip potential is applied, with respect to a reference electrode, using a potential programmer, and the current is measured with a simple amplifier device. The tip position may be viewed using a video microscope, (b) Schematic of the submarine UME configuration, which facilitates interfacial electrochemical measurements when the phase containing the UME is more dense than the second phase. In this case, the glass capillary is attached to suitable micropositioners and electrical contact is made via the insulated copper wire shown. 

In the experiments, signal transducer and activator of transcription 1 (STATl), in HeLa cells was selected for the visualized target. The experimental setup is depicted in Fig. 1. The most characteristic point of pin-fiber video-microscope is that its light source needs no interface, because it does not utilize evanescent light. Instrumentation... 

A video microscope is not required for an SECM instrument, but it is very useful and is a highly recommended addition. A video microscope is preferred over a normal optical microscope because it allows the probe to be continuously observed while operating the instrument. A video record of the experiment is also available. The video microscope aids in positioning the probe in generation/collection experiments, where the lack of a feedback response makes accurate distance control difficult. In addition, video microscopy helps in positioning the probe near features of interest on the substrate. 

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

The instrument described has been used mostly on polystyrene and polyethylene foams in cell sizes ranging from 0.1 to 2.0 nun. Figure 10.3 shows a schematic of the instrument. A study made with 14 different samples of polystyrene foam ranging from 0.17 to 1.61 m (microscopic method) showed a correlation coefficient of 0.9952 for the ASTM D 3576 shadowgraph method vs. 0.9964 for the video method. 

The technique of FT-IR internal ATR has been developed to the point that, today, ATR mirror lenses are available for an IR microscope. Furthermore, a newly developed, dedicated diamond internal reflection instrument, the lUuminatIR (Smith s Detection, Shelton, CT, USA) has now joined the ranks of microspectroscopy. This instrument incorporates a small, horizontally mounted diamond, on the surface of which is placed the material to be examined. In this way, the material is in optical contact with the diamond, and is held in place by a shaft pressing down from above. In this case, the radiation enters from beneath the instrument at an appropriate angle, and internally reflected rays are subsequently collected. The specimen is illuminated from beneath with a near-IR source that is detected and displayed on a video screen. With this optical arrangement, it is possible to locate a particular part of the material in the field of view and to interrogate it Such an arrangement is particularly user friendly, and indeed it is mostly used by... 

Fig. 5. A typical arrangement of the equipment needed for the microinjection of fertilized one-cell eggs. A Agla micrometer S5ringe. B Liquid-paraffin-filled tube. C Left-hand micromanipulator. D Inverted microscope. E Base plate. F Camera (optional). G Left-hand instrument tube for holding pipet. H Microinjection chamber (depression slide) sitting on fixed stage. I Right-hand instrument tube for injection pipet. J Air-filled tube. K Glass 50-mL syringe. L Right-hand micromanipulator. M Video system (optional).

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