The outdoor service life of common plastic materials is limited by their susceptibility to solar ultraviolet radiation. Of the solar wavelengths the UV-B component is particularly efficient in bringing about photodamage in synthetic and naturally occurring materials. This is particularly true of plastics, rubber and wood used in the building ...

This study reports an example of visible-light photocatalyst based on TiO2 modified by ruthenium-complex sensitizers and noble metal deposits. The photodegradation of trichloroacetate (TCA) and carbon tetrachloride was used as a probe reaction for evaluating the visible light activity of the photocatalyst under the illumination of lambda > 420 nm. ...

The human eye is exquisitely sensitive to light (i.e., visible radiant energy), and when dark-adapted, the retina can detect a few photons of blue-green light. It is therefore not at all surprising that ocular tissues are also more vulnerable to ultraviolet (UV) and light damage than the skin. For this ...

A treatment of the diatom Phaeodactylum tricornutum with high light (HL) in the visible range led to the conversion of diadinoxanthin (Dd) to diatoxanthin (Dt). In a following treatment with HL plus supplementary ultraviolet (UV)-B, the Dt was rapidly epoxidized to Dd. Photosynthesis of the cells was inhibited under HL ...

Whereas humans have three types of cone photoreceptor, birds have four types of single cones and, unlike humans, are sensitive to ultraviolet light (UV, 320-400 nm). Most birds are thought to have either a violet-sensitive single cone that has some sensitivity to UV wavelengths (for example, many non-passerine species) or ...

The phototropins are a family of membrane-associated flavoproteins that function as the primary blue light receptors regulating phototropism, chloroplast movements, stomatal opening, and leaf expansion in plants. Phot1, a member of this family, contains two FMN-binding domains, LOV1 and LOV2, within the N-terminal region and a C-terminal serine-threonine protein kinase ...

The mechanism of photoinhibition was investigated in three representative macroalgal species growing on the coast of Patagonia: the chlorophyte Ulva rigida C. Agardh, the rhodophyte Porphyra columbina Montagne and the phaeophyte Dictyota dichotoma (Huds.) Lamour. Dark adapted specimens were exposed to 15 min unfiltered solar radiation to induce photoinhibition, and ...

The effect of photoperiod on the ultraviolet radiation (UV)-induced toxicity of fluoranthene to glochidia of the freshwater mussel, Utterbackia imbecillis, was evaluated using a series of static renewal toxicity tests conducted using one of four different photoperiods (24 h light, 16 h light:8 h dark, 12 h light:12 h dark, ...

Light-regulated molecular switches that reversibly control biomolecular function could provide new opportunities for controlling activity in diagnostics, affinity separations, bioprocessing, therapeutics, and bioelectronics applications. Here we show that site-specific conjugation of light-responsive polymers near the biotin-binding pocket of streptavidin provides control of ligand binding affinity in response to UV and ...

Growing plants in an enclosed controlled environment is crucial in developing bioregenerative life-support systems (BLSS) for space applications. The major challenge currently facing a BLSS is the extensive use of highly energy-intensive electric light sources, which leads to substantial energy wastes through heat dissipations by these lamps. An alternative lighting ...

A quantitative assessment of the light field produced by a Waldmann PDT 1200 lamp is presented. A photodiode detector array capable of measuring a beam diameter of 30 cm was used to map the light field. The irradiance was measured as a function of voltage. For lamp-detector distances of 10 ...

We investigated the effects of an ambient dose of ultraviolet-B (UV-B) radiation on chamber-grown Pseudotsuga menziesii var. glauca (Beissn.) Franco (Douglas-fir) seedlings, to determine if the presence of UV-B radiation in the growth light regime induces tolerance to environmental stresses such as high light and drought. Douglas-fir seedlings were grown ...

The effects of 254 nm ultraviolet light (UV) radiation on aerobic plate count (APC) of egg shells were investigated. In the first experiment, eggs were exposed to UV treatment (7.35 mW/cm2) for 0, 15, 30, and 60 s. Three eggs from each treatment were aseptically collected and placed into sterile ...

Photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a highly attractive alternative technology for purification and deodorization of indoor air. The main objectives of this study were to demonstrate that a common fluorescent visible light (FVL) lamp can be used to effectively remove by PCO low concentrations of VOCs ...

The objective of this study was to compare the effect of various experimental factors on the photoisomerization of nitrobenzaldehyde. The experimental factors included light source, light energy, exposure time, light path distance and the concentration of nitrobenzaldehyde. The results showed that the photoisomerization of nitrobenzaldehyde increased with increasing light exposure. ...

Non-ionizing radiation, which is produced in large amounts by welding arcs, may induce photophthalmia, keratoconjunctivitis and cataracts. Retinal injuries resulting from exposure to electric welding arcs have been reported, but such injuries are not commonly seen and may be misdiagnosed. A case is described of bilateral maculopathy in a millwright ...

Light-grown broad bean (Vicia faba L.) seedlings were subjected to different intensities of UV-B radiation (0, 0.05, 0.15, 0.45, 0.90, 1.45 and 1.98 W m(-2)) for 7 h under photosynthetically active radiation (70 micromol m(-2) s(-1)) and then exposed to He-Ne laser (632.8 nm, 5.43 mW mm(-2)) radiation for 5 ...

An optical solution is described for the redistribution of the light reflected from a 400-m2 paraboloidal solar concentrating dish as uniformly as possible over an approximately 1-m2 plane. Concentrator photovoltaic cells will be mounted at this plane, and they require a uniform light distribution for high efficiency. It is proposed ...

This study measured the effect of germicidal ultraviolet (UV) light on Giardia lamblia and Giardia muris cysts, as determined by their infectivity in Mongolian gerbils and CD-1 mice, respectively. Reduction of cyst infectivity due to UV exposure was quantified by applying most probable number techniques. Controlled bench-scale, collimated-beam tests exposed ...

Solar ultraviolet radiation is considered to be injurious rather than necessary for most organisms living on the earth. It is reported that the risk of skin cancer in humans increases by the depletion of the ozone layer. We have examined the genotoxicity of solar ultraviolet, especially the longer wavelength light, ...

We investigated ascospore discharge in the perithecial fungus, Gibberella zeae. In a wind tunnel study that simulated constant rain and varying day and night lengths, the rate of ascospore release was approximately 8-30% greater under light than in complete darkness. Under constant light, ascospore discharge occurred at maximal rates at ...

The present study seeks quantitative measures for photoenhanced toxicity under natural light regimes by comparing the effects of an aromatic compound under natural and laboratory light. To this purpose, the influence of light irradiance and spectral composition on the extent of photoenhanced toxicity of acridine, a three-ringed azaarene, to the ...

Illumination-invariant detection of landmark features is a prerequisite for landmark navigation in insects. It is suggested that a contrast mechanism involving the UV and green receptors of insect eyes could guarantee a robust separation between natural objects as foreground and sky as background. Using a sensor with a UV and ...

Field studies were conducted to compare insect population levels in greenhouse crops covered with plastics that block the transmission of UV light in two wavelength ranges. Crops grown in greenhouses under a plastic that blocked UV light at wavelengths of 380 nm and below had lower numbers of aphids and ...

The protein-bound chromophores, which increase with aging in the human lens, act as UVA sensitizers, producing almost exclusively singlet oxygen in vitro. Direct irradiation of whole, aged human lenses with high intensity UVA light (200 mW cm(-2) for 24 hr), however, failed to produce singlet oxygen damage, as evidenced by ...

Wing colors of the four species of Chrysozephyrus butterflies were analyzed by a spectrophotometer. As the dorsal wing surface of males showed a strong reflectance when the specimen was tilted, measurements were made by the tilting method. The dorsal wing surface of males which appears green to the human eye ...

The European Light Dosimeter Network (ELDONET) has now been functional for more than four years. The network is based on dosimeters which measure radiation in three biologically relevant wavelength bands (UV-B, 280-315 nm; UV-A, 315-400 nm; and Photosynthetic Active Radiation, PAR, 400-700 nm). The ELDONET network is currently based on ...

The determinants of Xenopus laevis embryos that act before their first cell division are mandatory for the formation of mRNas required to establish the dorsal axis. Although their chemical identities are unknown, a number of their properties have long been recognized. One of the determinants is present in the cytoplasm ...

Although the occurrence of iatrogenic light-induced retinal toxicity is beyond doubt, several issues remain to be studied further. These include conflicting reports regarding the wavelength of light that is most hazardous; what mechanism contributes more significantly in the pathogenesis of light-induced retinal toxicity-photochemical or photothermal; why does it occur in ...

As in many parrots, the plumage of the budgerigar Melopsittacus undulatus reflects near-ultraviolet (UVA) wavelengths (300-400 nm) and exhibits UVA-induced fluorescence. However, there have, to our knowledge, been no tests of whether the yellow fluorescence observed under intense UVA illumination has any role in signalling. Four experiments were carried out ...

We present a theoretical analysis of the relationship between incoming radiance and irradiance. Specifically, we address the question of whether it is possible to compute the incident radiance from knowledge of the irradiance at all surface orientations. This is a fundamental question in computer vision and inverse radiative transfer. We ...

In capillary electrophoresis (CE), light flux passes through a capillary cell and is in most cases detected photometrically. Due to the thinness of the cell, a part of the light passes through the wall and misses hitting the sample. In most CE apparatuses, incident light is focused by converging lenses ...

In this study, a photocatalytic decolorization system equipped with immobilized TiO2 and illuminated by solar light was used to remove the color of wastewater. To examine the decoloring efficiency of this system, photocatalytic decolorization of an organic dye such as methylene blue was studied as an example. The effects of ...

The photosynthetic performance of Enteromorpha linza (L.) J. Agardh-Chlorophyceae was determined with a portable PAM instrument in situ and under seminatural radiation conditions in Patagonia, Argentina. Solar radiation was measured in parallel with a three-channel radiometer, ELDONET (Real Time Computer, Möhrendorf, Germany), in three wavelength ranges, UV-B (280-315 nm), UV-A ...

Folate-diplasmenylcholine (1,2-di-O-(Z-1'-hexadecenyl)-sn-glycero-3-phosphocholine; DPPlsC) liposomes have been shown to greatly enhance the potency of water-soluble antitumor agents via a selective folate-mediated uptake and acid-catalyzed endosomal escape mechanism (Rui et al. J. Am. Chem. Soc., 1998; 120:11213--18). This study describes an adaptation of this strategy for the delivery of chloroaluminum phthalocyanine tetrasulfonate ...

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO(2-x)N(x) have revealed an improvement over titanium dioxide (TiO2) under visible light (wavelength < 500 nanometers) in optical absorption and photocatalytic activity such as photodegradations of methylene blue ...

Observations of UV-B radiation in the area of the Antarctic Peninsula are described, with the objective to obtain an evaluation of the UV-B enhancements observed during ozone hole episodes, and compare these with equatorial values. The enhancements observed during Southern Hemisphere spring are described in terms of a specific case ...

Three filamentous and heterocystous N(2)-fixing cyanobacteria, Anabaena sp., Nostoc commune and Scytonema sp. were tested for the presence of ultraviolet-absorbing mycosporine-like amino acids (MAAs) and their induction by solar ultraviolet-B (UV-B) radiation. High performance liquid chromatographic (HPLC) studies revealed the presence of only one type of MAAs in all three ...

The aim of this study was to characterize the lenticular ultraviolet transmission of the Siberian hamster (Phodopus sungorus) and to probe the range of near-ultraviolet (UV-A, 315-400 nm) and visible wavelengths (400-760 nm) for modulating the photoperiodic regulation of its reproductive and immune systems. Ocular lenses from adult hamsters were ...

Liquid-phase deposition of sol-gel method derived hybrid glass materials is utilized for fabrication of UV-light-sensitive thin films. The hybrid glass material undergoes a surface-relief deformation when exposed to UV light. The observed deformation phenomenon is in the form of a physical expansion of the exposed areas. The UV light induced ...

BACKGROUND: The main mechanism of phototherapy for neonatal hyperbilirubinemia is the production and excretion of (EZ)- and (EE)-cyclobilirubin (4E,15Z- and 4E,15E-cyclobilirubin). Thus, the clinical efficacy of the light source for phototherapy must be evaluated by cyclobilirubin formation from (ZZ)-bilirubin in in vitro photoirradiation. METHODS: In the present study, we investigated ...

Pesticides with N,N-dimethyl and thiomethyl moieties (aminocarb, methiocarb and fenthion) were irradiated under artificial light (lambda > 290 nm) in an amorphous wax phase from Persica laevis DC. The effect of the presence of the wax on the photolysis rate differed in the three pesticides, increasing it in aminocarb, having ...

The alga Chlamydomonas nivalis lives in a high-light, cold environment: persistent alpine snowfields. Since the algae in snow receive light from all angles, the photon fluence rate is the critical parameter for photosynthesis, but it is rarely measured. We measured photon irradiance and photon fluence rate in the snow that ...

The potential of ketocarotenoids to protect the photosynthetic apparatus from damage caused by excess light and UV-B radiation was assessed. Therefore, the cyanobacterium Synechococcus was transformed with a foreign beta-carotene ketolase gene under a strong promoter leading to the accumulation of canthaxanthin. This diketo carotenoid is absent in the original ...

Near-ultraviolet light (UVA: 320-400 nm) constitutes a major part of sunlight UV. It is important to know the effect of UVA on the biological activities of organisms on the earth. We have previously reported that black light induces somatic-cell mutation in Drosophila larvae. To investigate which wavelength of the UVA ...

The induction of autofluorescence of melanins by UV radiation (330-380 nm) and near UV (400-440 nm) light (jointly called UV light) was studied in tissue sections using three commercially available mounting media. Only Immu-Mount (Shandon) was found suitable for this purpose. UV irradiation of melanins in sections mounted in this ...

The physicochemical properties of natural gray hair obtained from the heads of individuals and as well as commercial samples were investigated. No statistically significant differences were observed in terms of their central maximum diameter, central cross-sectional area, central ellipticity, average tensile strength, and average extent of transverse swelling between gray ...

Many coral reef fish are beautifully coloured and the reflectance spectra of their colour patterns may include UVa wavelengths (315-400 nm) that are largely invisible to the human eye (Losey, G. S., Cronin, T. W., Goldsmith, T. H., David, H., Marshall, N. J., & McFarland, W.N. (1999). The uv visual ...

We studied UV-induced photodestruction of the native forms of bacteriochlorophyll a (Bchl a) from chromatophores and light harvesting complexes (LHC) of the sulphur photosynthetic bacterium Chromatium minutissimum. Irradiation of chromato- phores with 365-nm light (Soret band) or 280-nm light (absorption region of aromatic amino acids) led to the destruction of ...

The photocatalysis of azo dye, Orange G, by P-25 anatase TiO2 was investigated in this research. The experiments were conducted in a batch reactor with TiO2 powder suspension. Four near-UV lamps were used as the light source. The experimental variables included solution pH level, amount of TiO2, illumination light intensity, ...