Applications, microscopy fibers

Applications of fiber-optic pH sensors in environmental analysis, biomedical research, medical monitoring, and industrial process control have been reviewed by Lin [67]. A multitude of luminescent systems for pH monitoring are commercially available, mostly under special trademarks. Pyrene [68-70], coumarin, bromothymol blue [71] and fluorescein [72-74] derivatives are typical examples that have been used in research in the past two decades. Carboxyfluorescein derivatives have been directly applied to skin tissue samples for the lifetime imaging of pH gradients in the extracellular matrix of the epidermis [75]. Two-photon excitation microscopy became an estab-... 

Natural and synthetic textile fibers were among the earliest materials studied by electron microscopy. Guthrie [1] and Stoves [2] described the techniques and applications of fiber microscopy to industrial practice. Somewhat later, evidence was provided for an oriented microfibrillar texture in polymer fibers [3]. X-ray diffraction suggested an arrangement of fine structures about 50 nm long and 5 nm wide in semicrystalline fibers [4, 5]. Peterlin [6, 7] observed the formation of fibrils and microfibrils by the deformation and transformation of spheru-lites using various nucroscopy techniques. 

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

Jureller, J. E., Scherer, N. F., Birks, T. A., Wadsworth, W. J. and Russell, P. S. J. (2003). Widely tunable femtosecond pulses from a tapered fiber for ultrafast microscopy and multiphoton applications. In Ultrafast Phenomena xiii (Miller, R. J. D., ed.). Springer, Berlin, pp. 684-6. 

Petrov, G. L, and Yakovlev, V. V. 2005. Enhancing red-shifted white-light continuum generation in optical fibers for applications in nonhnear Raman microscopy. Opt. Express 13 1299-1306. 

Fluorescence sensors for saccharides are of particular interest in a practical sense. This is in part due to the inherent sensitivity of the fluorescence technique. Only small amounts of a sensor are required (typically 10-6 M), offsetting the synthetic costs of such sensors. Also, fluorescence spectrometers are widely available and inexpensive. Fluorescence sensors have also found applications in continuous monitoring using an optical fiber and intracellular mapping using confocal microscopy. 

Lack of advances in optics has hampered improvements in microscopic imaging. Development of adaptable, inexpensive fiber optics to transmit high-energy femtosecond pulses from mode-locked lasers, custom phase plates, and miniature laser beam scanners for endoscopic microscopy instruments offer the potential for enormous advances in laser scanning microscopy for various applications, including medical diagnostics and surgery. 

In the previous symposium, we reviewed mesophase mechanisms involved in the formation of petroleum coke ( 2 ). Since 1975, two significant developments have been the use of hot-stage microscopy to observe the dynamic behavior of the carbonaceous mesophase in its fluid state (3-6), and the emergence of carbon fibers spun from mesophase pitch (7-9) as effective competitors in applications in which high elastic modulus or good graphiticity is important. This paper focuses on mesophase carbon fibers as an example of how the plastic mesophase can be manipulated to produce fibers with intense preferred orientations and elastic moduli that approach the theoretical limit for the graphite crystal in the a-direction. 

Application of either PCM or TEM methods to the determination of asbestos fibers in biological or environmental media (air or water) requires that the fibers be separated from interfering material and collected on appropriate supports. Methods for preparing biological and environmental samples for microscopy are described below. 

Finally, the surface and bulk compositions of these fibers can vary dramatically. Figures 5 and 6 show the scanning Auger microscopy (SAM) profiles of SGN and HPZ ceramic fibers, respectively. Because the fiber-matrix interfaces are critical in many applications (2), this type of characterization of fiber surface composition and chemistry must be carried out. 

FIGURE 10.30 Scanning electron microscopy (SEM) images of cross section of a commercial optical fiber coated with a NaA zeoUte thick layer (a) total cross section and (b) magnification view of the NaA zeolite layer. (From Lopez, J., Pina, M.P., Coronas, J., Pelayo, J., and Santamaria, J., A novel optical device for gas sensor applications based on zeolitic materials. Books of abstracts of the 1st NanoSpain Workshop, San Sebastian, 2004.)... 

---