Search results for "ultraviolet"
showing 10 items of 853 documents
Microorganisms in the Space Environment
1984
Preliminary results of the Spacelab 1 experiment on the response of Bacillus subtilis spores to conditions of free space are presented. Exposure to the vacuum of space on the Spacelab pallet reduced viability counts about 50 percent and increased mutation frequencies by a factor of about 10. Interpretation of apparent differences in the photobiological and photochemical data between flight and ground simulation experiments will require more statistical analyses and data from actual fluence measurements.
High-precision measurements of the hyperfine structure of cobalt ions in the deep ultraviolet range
2023
Scientific reports 13(1), 4783 (2023). doi:10.1038/s41598-023-31378-1
Attraction of kestrels to vole scent marks visible in ultraviolet light
1995
IN northern Europe, broad four-year oscillations in small rodent and raptor populations are synchronous over hundreds of square kilometers1–6. Crashes in vole populations can induce wide emigration (> 1,000 km) of their predators7 –9, but almost nothing is known about how predators rapidly detect areas of vole abundance. Here we report on laboratory and field experiments on voles (Microtus agrestis) and kestrels (Falco tinnunculus). Voles mark their runaways with urine and faeces, which are visible in ultraviolet light. Wild kestrels brought into captivity were able to detect vole scent marks in ultraviolet light but not in visible light. In the field, kestrels hunted preferentially near ex…
Derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone 4-sulfonic acid into solid-phase extraction cartridges. Determination of am…
1997
The derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone-4-sulfonate (NQS) into solid-phase extraction cartridges (C 18 ) is described. Optimum conditions were the use of carbonate–hydrogencarbonate buffer of pH 10, a 10 min reaction time at 25 °C and an NQS concentration of 9.6 × 10 - 3 M. The accuracy and the precision of the method were tested. The results obtained with the proposed liquid–solid procedure were compared with those obtained with a traditional liquid–liquid extraction with hexane–ethyl acetate. The procedure was used to measure amphetamine in pharmaceutical and urine samples
IL-10 Controls Ultraviolet-Induced Carcinogenesis in Mice
2007
Abstract UV radiation-induced immunosuppression contributes significantly to the development of UV-induced skin cancer by inhibiting protective immune responses. IL-10 has been shown to be a key mediator of UV-induced immunosuppression. To investigate the role of IL-10 during photocarcinogenesis, groups of IL-10+/+, IL-10+/−, and IL-10−/− mice were chronically irradiated with UV. IL-10+/+ and IL-10+/− mice developed skin cancer to similar extents, whereas IL-10−/− mice were protected against the induction of skin malignancies by UV. Because UV is able to induce regulatory T cells, which play a role in the suppression of protective immunity, UV-induced regulatory T cell function was analyzed…
Luminescence spectroscopy under synchrotron radiation: From SUPERLUMI to FINESTLUMI
2020
Abstract Luminescence spectroscopy under synchrotron radiation excitation is the unique tool for materials characterization. In the current work we are reporting recent activity in this research field implemented in the Finnish-Estonian beamline (FinEstBeAMS) which is installed at the 1.5 GeV storage ring of the MAX IV Laboratory at Lund, Sweden. It has been designed to cover an unusually wide energy range from ultraviolet (4.3 eV) to soft X-rays (1500 eV), which is perfectly suited for luminescence spectroscopy experiments. The past development and the present technical parameters of the luminescence experimental stations FINESTLUMI of FinEstBeAMS beamline are described. The comparison of …
Combined High Dose and Temperature Radiation Effects on Multimode Silica-Based Optical Fibers
2013
International audience; We investigate the response of Ge-doped, P-doped, pure-silica, or Fluorine-doped fibers to extreme environments combining doses up to MGy(SiO $_{{{2}}}$) level of 10 keV X-rays and temperatures between 25 C and 300 C . First, we evaluate their potential to serve either as parts of radiation tolerant optical or optoelectronic systems or at the opposite, for the most sensitive ones, as punctual or distributed dosimeters. Second, we improve our knowledge on combined ionizing radiations and temperature (R&T) effects on radiation-induced attenuation (RIA) by measuring the RIA spectra in the ultraviolet and visible domains varying the R&T conditions. Our results reveal the…
UV–VUV laser induced phenomena in SiO2 glass
2004
Abstract Creation and annihilation of point defects were studied for SiO2 glass exposed to ultraviolet (UV) and vacuum UV (VUV) lights to improve transparency and radiation toughness of SiO2 glass to UV–VUV laser light. Topologically disordered structure of SiO2 glass featured by the distribution of SiOSi angle is a critical factor degrading transmittance near the fundamental absorption edge. Doping with terminal functional groups enhances the structural relaxation and reduces the number of strained SiOSi bonds by breaking up the glass network without creating the color centers. Transmittance and laser toughness of SiO2 glass for F2 laser is greatly improved in fluorine-doped SiO2 glass…
Iron-related luminescence centers in ZnWO 4 :Fe
2002
A systematic spectroscopic study of single ZnWO4 :Fe crystals with different iron concentrations has been performed under excitation by ultraviolet light, by synchrotron radiation or under photostimulation by near-infrared light. The luminescence of Fe3+-related centres has been studied. It is shown that iron centres of different types efficiently promote the formation of crystal defects at low temperatures. Electrons and holes can be trapped near Fe2+ or Fe3+ ions, which is further revealed in phosphorescence, thermostimulated or photostimulated luminescence. At room temperature the main effect of iron impurity is to reduce the light yield of a ZnWO4 scintillator.
Luminescence mechanisms of oxygen-related defects in AlN
2002
Spectral characteristics of native oxygen-related defects existing in the crystalline lattice of AlN were studied. Features of photoluminescence observed under exposure to ultraviolet light together with those of the photostimulated luminescence testify the recombination character of luminescence. The mechanism of luminescence of oxygen-related defects is proposed.