Magnetically coupled devices

The solid material is placed into a small vial that is introduced into a thermostated high-pressure chamber (volume 79 ml). The vial is attached to a suspension device that is magnetically coupled to the balance during measurement. The device is lowered to a neutral position when no recording of a mass point takes place, thus allowing for the balance to be tared before each measurement. This is of particular importance in slow processes in which thermodynamic equilibrium is attained only in the course of several hours or even days. The chamber may be evacuated with a vacuum pump at the beginning and at the end of each experiment. The dense gas is taken from a cylinder and, if necessary, compressed to system pressure with the help of a membrane piston pump. 

CD = circular dichroism CCD = charge coupled device EPR = electron paramagnetic resonance FTIR = fourier transform infra-red FWHM = full width (at) half maximum MCD = magnetic circular dichroism MLCT = metal-to-ligand charge-transfer NMR = nuclear magnetic resonance OPOs = optical parametric oscillators PSII = photosystem 11. 

Some of the problems seen with the commercially available polyimides such as limited shelf life,gelation and high ionic contamination are traceable to the raw materials themselves. A zone refining technique has been perfected for use with organic materials and these precursors have been used to synthesize ultrapure polyamic acids for IC device applications. The key feature of the synthesis is the use of solid ingots of the dianhydrides. Materials prepared by this technique show low metallic impurities and have been shown to be excellent film formers for a variety of applications. In particular a polyimide derived from PMDA-ODA has been used to passivate magnetic bubble devices. IR techniques coupled with electrical measurements have been used to optimize the cure conditions and a simple resist process has been defined to passivate these devices. Device performance compares well with conventional inorganic insulators. 

A fundus camera was modified to provide video angiograms and to deliver one laser beam used to release the content of the liposomes and another laser beam to activate the photosensitizer. The first laser was also used to illuminate the fundus. The output of the charge-coupled device (CCD) camera was fed into a video image enhancer and recorded on magnetic tapes with a high-frequency video recorder. Later, the tape was played back, and video sequences were digitized with a frame grabber for subsequent analysis. 

Figure 2.10(b) illustrates a mutual-inductance sensor which employs two separate coils and uses the variation in their mutual magnetic coupling to measure displacement. These devices can be used to measure cardiac dimensions, monitor infant respiration and ascertain arterial diameters [2]. 

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