Real-time optical information processing

The purple membrane is harvested semiindustrially from halobacteria mutants which are bred in fermenters. The BR is then embedded into a polymeric matrix of poly(vinyl alcohol) or polyacrylamide. The BR films manufactured in this way are used for different applications, preferably in holography, for example, as a reversible transient data storage system for optical information processing (159). Another example is real-time interferometry by using the property of BR films to integrate over time (160). BR has been proposed also as a two-photon memory material because of its unusually large two-photon cross section. 

Remote IR fiber-based spectroscopy allows real-time exploration of chemical reactions and, as a consequence, provides a valuable tool to access information on complex reaction mechanisms. For instance Anne et al. [160] have monitored in real time, the polymerization process of an industrial thermohardening resin using a Ge-Ga-Sb-Se optical fiber, while Li et al. employed a similar process to characterize the polymerization of styrene films [161]. In the food industry, Le Coq et al. quantitatively monitored the conversion of fructose and glucose into ethanol during the fermentation process of cider [162]. Differentiation of egg white versus egg yolk has also been demonstrated [163]. 

The objective ia any analytical procedure is to determine the composition of the sample (speciation) and the amounts of different species present (quantification). Spectroscopic techniques can both identify and quantify ia a single measurement. A wide range of compounds can be detected with high specificity, even ia multicomponent mixtures. Many spectroscopic methods are noninvasive, involving no sample collection, pretreatment, or contamination (see Nondestructive evaluation). Because only optical access to the sample is needed, instmments can be remotely situated for environmental and process monitoring (see Analytical METHODS Process control). Spectroscopy provides rapid real-time results, and is easily adaptable to continuous long-term monitoring. Spectra also carry information on sample conditions such as temperature and pressure. 

Since the sensitivity of pulse NMR is very high and H Ti values for usual polymers are less than 1 s due to the spin diffusion, rapid measurements with short repetition times are possible. This gives us the real time measurement of nonequilibrium phenomena such as crystallization in the polymer. The crystallization process of polymers has been studied by an optical microscope, dilatometry and X-ray diffraction. These methods only gives static information about the crystallization process. The pulse NMR measurements provide both the fraction and the molecular mobility of each phase. Figures 7.19 and 7.20 show the temperature change of the fractions and T2 values of crystalline, interfacial and amorphous components for poly(e-caprolactone)... 

The number one advantage of optical SPR biosensors is their abihty to measure complex formation in real time. This makes it possible to obtain quantitative information about binding interactions including the assembly and break down process. The majority of binding interactions that we encounter on a routine basis are simple bimolecular interactions. Two molecules must come together in space to form a complex. We typically depict these systems as a simple A + B goes to AB reaction as shown below ... 

Bulk characterization yields information on the macroscopic properties of the biomaterial such as thermal, mechanical, solubility, optical, and dielectric properties. Surface characterization yields morphological information that is critical for interfacing the implant or drug delivery device with the host tissue. This could be achieved by microscopic and spectfoscopic methods. Next in the hierarchy is the characterization of processes such as biodegradation mechanism and kinetics under biomimetic in vitro conditions. Cases of implanted device failure need to be assessed by systematic interrogation of explanted medical devices. After knowing the basic characteristics of the biomaterial, real-time investigation of in vivo processes plays a major role in the successful journey of an implant. 

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