We have fabricated long-period fiber gratings by use of a novel technique using focused irradiation of infrared femtosecond laser pulses. We investigate the thermal stability of the fabricated fiber gratings. The values of the loss peak wavelength and the transmittance of the fiber gratings after heat treatment below 500 degrees C are the same as initial values before heat treatment. The fiber gratings that were fabricated by this technique have a high resistance to thermal decay. We propose that this technique will be useful for fabrication of fiber gratings with a superior aging characteristic.

Brucella spp. are facultative intracellular pathogens that have the ability to survive and multiply in professional and nonprofessional phagocytes and cause abortion in domestic animals and undulant fever in humans. The mechanism and factors of virulence are not fully understood. To identify genes related to internalization and multiplication in host cells, Brucella abortus was mutagenized by mini-Tn5Km2 transposon that carryied the kanamycin resistance gene, 4,400 mutants were screened, and HeLa cells were infected with each mutant. Twenty-three intracellular-growth-defective mutants were screened and were characterized for internalization and intracellular growth. From these results, we divided the mutants into the following three groups: class I, no internalization and intracellular growth within HeLa cells; class II, an internalization similar to that of the wild type but with no intracellular growth; and class III, internalization twice as high as the wild type but with no intracellular growth. Sequence analysis of DNA flanking the site of transposon showed various insertion sites of bacterial genes that are virulence-associated genes, including virB genes, an ion transporter system, and biosynthesis-and metabolism-associated genes. These internalization and intracellular-growth-defective mutants in HeLa cells also showed defective intracellular growth in macrophages. These results suggest that the virulence-associated genes isolated here contributed to the intracellular growth of both nonprofessional and professional phagocytes.Brucellosis is a major bacterial zoonosis that causes a serious debilitating disease in humans and abortion and sterility in domestic animals. The etiologic agents of brucellosis are Brucella spp., small gram-negative and facultative intracellular pathogens that can multiply within professional and nonprofessional phagocytes (9, 10). In contrast to other intracellular pathogens, Brucella species do not produce exotoxins, antiphagocytic capsules or thick cell walls, resistance forms, or fimbriae and do not show antigenic variation (16). A key aspect of the virulence of brucella is its ability to proliferate within professional and nonprofessional phagocytic host cells and thereby successfully bypasses the bactericidal effects of phagocytes, and their virulence and chronic infections are thought to be due to their ability to avoid the killing mechanisms within host cells (30, 41). The molecular mechanisms and genetic basis for intracellular survival and replication, however, are not understood completely. Some studies with nonprofessional phagocytes have shown that Brucella invades host cells and is contained within early endosome-like vacuoles. These vacuoles rapidly fuse with early autophagosomes that acquire vacuolar [H ϩ ]ATPase and lysosome-associated membrane proteins (LAMP), mature into a late autophagosome, inhibit fusion with lysosomes, and finally become a replicating vacuole normally associated with the endoplasmic reticulum (5,11,31,32). The genetic basis of Brucella virul...

Analysis of energy transfer processes in Yb3+-Tb3+ co-doped, low-silica calcium aluminosilicate glasses J. Appl. Phys. 110, 083108 (2011); 10.1063/1.3653272Long-lasting phosphorescence in Sn 2+ -Cu 2+ codoped silicate glass and its high-pressure treatment effect

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We demonstrate the three-dimensional microdrilling of glass by the multiphoton process with nonresonant femtosecond laser pulses and by the subsequent chemical etching. We use photomachinable glass which is sensitive to cw UV light of a wavelength shorter than 320 nm. After the focused irradiation of nonresonant femtosecond laser pulses at 400 nm and subsequent heat treatment, crystallites of Li2O·SiO2, which are more soluble in dilute hydrofluoric acid than matrix glass, precipitate in the focused area of the laser within the glass sample. After etching the crystallites, three-dimensional holes are formed in the glass sample. We produce straight and Y-branched holes in the glass sample. This technique can be applied to the fields of microoptics, microelectronics and microchemicals.