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We investigate an improvement in the pump slope efficiency for an erbium-doped fiber-ring laser. The method is based on the residual pump power reused by means of a fiber mirror. Under the conditions of a 4-m erbium-doped fiber (EDF), 10 mW of pump power, and a 99% reflectivity of a fiber-Bragg grating, the pump slope efficiency may reach 19.70% compared to 15.37% for a conventional fiber-ring laser. The maximum lasing power is increased from 14.6 to 18.7 mW corresponding to a 1.07-dB lasing power enhancement. The side-mode suppression ratio is as high as 67.6 dB with a line width of less than 0.05 nm.

In this work, polyacrylonitrile (PAN)-based activated carbon fibers (ACFs) were developed by the common processes of stabilization, carbonization, and steam activation. Those fibers were successively subjected to heat treatment in a vacuum at high temperature and reactivation in steam. The changes in specific surface area and surface chemical characteristics were studied. The vaccum treatment reduced the surface area dramatically, while the surface nitrogen decreased after activation in steam and the surface oxygen was lowered upon the vaccum treatment. By curve-fitting the X-ray photoelectron spectroscopy (XPS) of C1s, O1s, and N1s, it was shown that the forms and compositions of the oxygen-containing functionalities seemed not to be affected significantly by the above-mentioned heat-treat-ment processes, whereas the nitrogen-containing functionalities showed some changes with these treatments. © 1996 John Wiley & Sons, Inc.

X-ray diffraction of the UHMWPE gel-films has shown that high heating rate annealing of the films causes deformation of the crystallites. The apparent crystal sizes change with the annealing temperature (Ta). With Ta below 110°C, the dimensions of the crystallites in c-axis (Lc) increase associated with the decreasing in a-axis (La) and b-axis (Lb), but the changes are small because of the higher energy barrier. When Ta is raised to 138°C, Lc is nearly doubled its value at 60°C whereas Lb increases and La remains unchanged. IR spectral subtraction was applied to reveal the morphological changes of the gel-films upon annealing. It has been found that bands of the same type of conformation have different sensitivities subject to the thermal treatment at different annealing temperatures. The results can be understood by assuming the changing process being completed through chain segments sliding along the (020) sectors. © 1995 John Wiley & Sons, Inc.

We present the results and critical analyses of recent studies of ultrafast optical nonlinearities of liquid crystals in the isotropic and ordered phases for time scales spanning femtoseconds – microseconds. Pure undoped liquid crystals as well as liquid crystals containing plasmonic nano-particles have been investigated. Individual molecular electronic optical nonlinearities are found to be useful for femtoseconds – nanoseconds nonlinear transmission clamping applications. On the other hand, laser induced order parameter and birefringence modification in aligned nematic cells allow very rapid transmission switching of visible as well as near infrared lasers with response times in the sub-microseconds - few nanoseconds regime.

Sound transmission and absorption of multi-layer sound absorbents are discussed in this manuscript. A new matrix formulation based on four pole parameters is utilized to derive the transmission loss and absorption coefficient of the absorbents. A transfer matrix relating pressure to acoustic velocity provides the required information to calculate the transmission loss and absorption coefficient. The multi-layer sound absorbents considered are structural panels, elastic porous linings and air-gaps. No limitations are imposed on the number of layers. Some realistic configurations of a multi-layer sound absorbent are studied to demonstrate the applicability of the four-pole parameter technique.

We have used Ca2+-dependent binding to a phospholipid vesicle affinity column to isolate a mixture of three synexin-like proteins from the cytosol of human polymorphonuclear leukocytes (PMN), with relative molecular weights of approximately 67,000, 47,000, and 28,000. Rabbit antibodies raised against bovine liver synexin recognized the 47,000 molecular weight PMN protein. These PMN proteins, like bovine liver synexin, promoted aggregation of isolated PMN specific granules in the presence of Ca2+ and increased the overall rate of Ca2+-induced fusion of liposomes composed of phosphatidate (PA)/phosphatidylethanolamine (PE) (1:3) and phosphatidylserine/PE (1:3), but decreased the rate of spermine-induced fusion of PA/PE (1:3) liposomes. Using fluorescent lipid probes, rapid fusion of PA/PE liposomes with PMN specific granules (50% maximum signal within a few minutes) was observed when 1 mM Ca2+ was added in the presence of both synexin and free arachidonic acid. Dilution of the aqueous contents of liposomes was also observed under the same conditions. The rate of fusion increased monotonically with Ca2+ and arachidonic acid concentrations, but synexin exhibited an optimum concentration. Lack of any one of the components precluded rapid fusion. These results suggest that PMN contain a protein similar to, or identical with, synexin that may be involved in calcium-dependent fusion of intracellular membranes.

The authors have examined the fate of intravitreally injected liposomes in the aphakic, vitrectomized eye of the rabbit. Liposomes labelled with 125[I]-p-hydroxybenzimidylphosphatidylethanolamine were eliminated rapidly from the intraocular fluid. Nonetheless, a significant fraction of these liposomes were found to bind to various ocular tissues including the retina, iris, sclera, and cornea. Ultrastructural studies with gold colloid-loaded liposomes revealed that retinal bound liposomes were attached to the inner limiting lamina but did not penetrate to the internal cells of the retina. Epiretinal cells bound and internalized gold colloid-loaded liposomes suggesting that these cells may be very sensitive to liposome mediated drug delivery.