UV Exposure Conditions Research Articles

Assessment of the phototoxicity of weathered Alaska North Slope crude oil to juvenile pink salmon

Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assessed the acute phototoxicity of the water accommodated fractions of weathered Alaska North Slope crude oil (ANS) to juvenile pink salmon, which are a heavily pigmented life stage. Fish in the highest ANS treatments exhibited melanosis, less mobility, reduced startle response, erratic swimming, and loss of equilibrium. Gills from fish exposed to ANS had elevated levels of hydroperoxides in oil-only, UV-only, and oil + UV treatments compared to control fish, which was indicative of increased lipid peroxidation in gill tissue. Under the test conditions of moderate salinity, low UV and high short-term oil exposure there were no indications of photoenhanced toxicity as assessed by elevation of mortality, behavioral impairment, or gill lipid peroxidation in oil + UV treatments. The results of this study suggest that pink salmon may be at less risk from photoenhanced toxicity compared to the translucent early-life stages of several other Alaska species.

Photoactivatable copolymers of vinylbenzyl thiocyanate as immobilization matrix for biochips.

Biochip surfaces for immobilization of DNA and proteins require reactive polymers with high immobilization capacity and low nonspecific binding. Most reactive surfaces consist of matrixes that provide epoxy, aldehyde, or amino functions for biomolecule binding. The most widely used oligonucleotide modification is a C6-amino link. The high reactivity of isothiocyanate groups (NCS) toward amines was therefore the motivation to employ photogenerated NCS groups as binding sites for NH(2)-terminated oligonucleotides. Photosensitive poly(styrene-co-4-vinylbenzyl thiocyanate) (PST-co-VBT) was synthesized and applied as novel material for DNA and protein immobilization. The immobilization capacity of PST-co-VBT was a function of UV energy density used for photoactivation and was approximately 80% at 450 mJ cm(-)(2) (lambda(ex) = 254 nm). This surface was superior to tested commercial chip surfaces in signal-to-noise-ratio and reproducibility. Print buffer and spacer length were optimized for maximum fluorescence signal with DNA and proteins. UV exposure conditions and oligonucleotide modification were correlated, showing that this photochemical approach can be successfully applied for surface patterning of biochips.

Mycosporine-like amino acids in planktonic organisms living under different UV exposure conditions in Patagonian lakes

Mycosporine-like amino acids (MAAs) were studied in zooplankton from 13 Argentinian lakes covering a broad range in altitude, maximum depth and physico-chemical properties of the water. Four to nine different MAAs (predominantly porphyra-334 and shinorine) were found in the copepods Boeckella gibbosa, B. gracilipes, B. meteoris and Parabroteas sarsi, and in the ciliate Stentor amethystinus, while MAAs were undetectable in the cladoceran Daphnia middendorffiana. Among the different copepods, maximum MAA concentrations accounted for 0.25-1.31% of the dry weight, and contents were generally about three to seven times (up to 43 times) higher in the animals living in the clearest lakes compared to those occurring in low-UV systems. This variability in the content of MAAs was related to the lake altitude (r(2) = 0.71), and the fraction of the water column to which 1% of the surface UV radiation at 320 nm penetrated (r(2) = 0.57). Our data therefore underscore the role of MAAs as sunscreens to decrease the potential negative effects of solar radiation, but they also indicate that other environmental factors besides UV transparency play a role in determining MAA concentrations. One lake was selected to obtain additional information on the qualitative composition of MAAs in seston of <100 μm between two sampling sites and over a 2 month study period (austral summer). Six different MAAs were detected in the samples, with porphyra-334 and palythine being predominant. In the copepods collected simultaneously, there was low variation in MAA concentrations between the two sites and over time. Thus, our results suggest that under similar UV exposure conditions MAA contents of planktonic organisms show low temporal variation.

Photocatalytic degradation of organic compounds over combustion-synthesized nano-TiO2.

The photocatalytic degradation of various organics such as phenol, p-nitrophenol, and salicylic acid was carried out with combustion-synthesized nano-TiO2 under UV and solar exposure. Under identical conditions of UV exposure, the initial degradation rate of phenol with combustion-synthesized TiO2 is 2 times higher than the initial degradation rate of phenol with commercial Degussa P-25 TiO2. The intermediates such as catechol (CC) and hydroquinone (HQ) were not detected during the degradation of phenol with combustion-synthesized TiO2, while both the intermediates were detected when phenol was degraded over Degussa P-25. This indicates that the rates of secondary photolysis of CC and HQ occur extremely faster than the rates at which they are formed from phenol and further implies that the primary hydroxylation step is rate limiting for the combustion-synthesized TiO2 aided photodegradation of phenol. The degradation rates of salicylic acid and p-nitrophenol were also investigated, and the rates were higher for combustion-synthesized titania compared to Degussa P-25 TiO2. Superior activity of combustion-synthesized TiO2 toward photodegradation of organic compounds can be attributed to crystallinity, higher surface area, more surface hydroxyl groups, and optical absorption at higher wavelength.

UV-induced polarisation-dependent loss (PDL) in tilted fibre Bragg gratings: application of a PDL equaliser

By using a zero-order-nulled phase mask, tilted fibre Bragg gratings (FBG) were fabricated in standard telecommunications fibre that have a near constant polarisation-dependent loss (PDL) across a wide wavelength range (λ=1500 to 1580 nm). The near constant PDL of the FBG device was produced by precise control of grating blaze angle, while the magnitude of the PDL was controlled through UV exposure conditions and device length. In this fashion a device with an arbitrary PDL value could be fabricated. By optically coupling the devices to an optical component or system requiring polarisation equalisation, the resultant PDLs of the systems were minimised by orienting the gratings of the PDL equaliser about its optical axis to lessen the inequality in output states of polarisations.

Large variability in the concentration of mycosporine‐like amino acids among zooplankton from lakes located across an altitude gradient

The qualitative and quantitative composition of mycosporine‐like amino acids (MAAs), a family of intracellular UV‐absorbing compounds, were investigated in zooplankton from 15 lakes located in the Central Alps between 913 and 2,485 m above sea level. The lakes differed in their UV water transparency (1% attenuation depth, Z1%, at 320 nm: 1.1–25.6 m) and maximum depth (Zmax: 3–133 m), thus offering the possibility to test the influence of different UV exposure conditions of zooplankton on the concentration of MAAs. Seven distinct MAAs were detected, but shinorine (maximum absorption: 334 nm) was the predominant compound. In the copepods Cyclops abyssorum, C. abyssorum tatricus, and Acanthodiaptomus denticornis, the total MAA concentration ranged from 0.01 to 3.1% of the dry weight. In the rotifers Keratella cochlearis and Polyarthra dolichoptera, MAAs were also found; however, these compounds were undetectable in Asplanchna priodonta as well as in the cladocerans Daphnia hyalina, D. longispina, Bosmina longispina, and Chydorus sphaericus. The total concentration of MAAs in populations of Cyclops spp. and phytoplankton collected simultaneously was not associated (r2 = 0.09, P &gt; 0.05), suggesting a different dynamic in the accumulation of these compounds. The variability in the concentration of MAAs, however, was related with the diffuse attenuation coefficient at 320 nm (r2 = 0.74, P &lt; 0.001) and the fraction of the water column to which 1% of the surface irradiance at 320 nm (Z1% : Zmax) penetrated (r2 = 0.86, P &lt; 0.001). These relationships suggest that the prevailing UV exposure condition in the lakes is a major determinant of the concentration of MAAs found in zooplankton. Our data support the hypothesis that MAAs, together with other photoprotective compounds, play a major role in minimizing the damaging effects of solar UV radiation in zooplankton from transparent lakes.

Optically Controlled Alignment of Liquid Crystal on Polyimide Films Exposed to Undulator Radiation

Liquid crystal (LC) alignment properties on photo-exposed polyimide films were studied in the UV and VUV regions using linearly polarized synchrotron radiation from the Onuki-type polarizing undulator installed in the electron storage ring NIJI-II in ETL. It was found that the LC alignment uniformity depends on the UV and VUV exposure conditions, especially on the wavelength of the radiation. The photoabsorption spectrum of polyimide films was also measured in both UV and VUV regions. It was concluded that at least two mechanisms exist in the photo-induced alignment of LC molecules on the polyimide films.

EEC/COLIPA project on in vitro phototoxicity testing: First results obtained with a Balb/c 3T3 cell phototoxicity assay

In a joint validation project eight laboratories from the European Cosmetic Industry Association (COLIPA) as well as FRAME (England) and ZEBET (Germany) are trying to develop validated in vitro methods to be incorporated into new international guidelines for acute phototoxicity testing. The first stage of the study involved selection of the most promising in vitro phototoxicity tests for further validation. 20 chemicals with known phototoxic properties (12 phototoxins, four UV-absorbing non-phototoxins and four non-UV absorbing non-phototoxins) were tested under identical conditions of UV exposure conditions (sun simulator, UVA 5 J/cm 2) in a standardized cytotoxicity assay with Balb/c 3T3 fibroblasts (endpoint: neutral red uptake, NRU). 19 of the 20 chemicals were correctly classified by the 3T3 NRU phototoxicity test, and therefore, this simple assay for phototoxicity seems very promising and should be validated further.

Photosensitive Polyimide as a Dielectric in High Density Thin Film Copper‐Polyimide Interconnect Structures

A photosensitive polyimide is evaluated as a dielectric material in high density thin film copper‐polyimide interconnect structures. Factors affecting the photolithographic fabrication of structures with small feature size and high aspect ratio have been investigated. The shrinkage characteristics of the precursor film were observed to depend strongly on the UV exposure conditions. Dimensional changes taking place during curing of the polyimide structures show anisotropic shrinkage, the degree of which depends upon the feature size. The photosensitive polyimide precursor is observed to interact strongly with copper and results in residue formation during patterning. Based on this photosensitive polyimide process, high density thin film copper‐polyimide interconnect structures with wiring density close to 800 lines per centimeter were fabricated.