Single UV Radiation Research Articles

Significantly enhanced antifouling and separation capabilities of PVDF membrane by synergy of semi-interpenetrating polymer and TiO2 gel nanoparticles

PVDF membrane has strong hydrophobicity and low anti-pollution performance, greatly limiting its practical application. These drawbacks have been successfully overcome by designing and then preparing a membrane with a semi-interpenetrating polymer (semi-IPN) of PVDF/poly(acrylic acid) (PAA) as the membrane matrix, TiO2 nanoparticles as functional components and F127 as pore-forming agent. The semi-IPN was prepared by copolymerizing acrylic acid with N,N methyl acrylamide in the presence of PVDF, and the TiO2 gel nanoparticles were in situ formed in the membrane-forming process. The properties of the composite membrane were significantly affected by the semi-IPN, F127 and TiO2. By adjusting the membrane structure with the semi-IPN, F127 and TiO2 nanoparticles, we prepared a composite membrane with a water contact angle of 40°, a BSA rejection ratio of 87.5% and a water flux of 802.5 L/m2/h/bar. After a simple UV irradiation, the water flux of this composite membrane rose to 1030 L/m2/h/bar, without any rejection decline. The membrane contaminated by humic acid could recover the water flux up to above 95.3% of its original value by a single UV irradiation, showing a very good antifouling performance. In addition, the composite membrane also exhibited a very strong pollution resistance and separation performance for bovine serum albumin and oil-water emulsion. All in all, based on the synergy of the semi-IPN and the evenly dispersed TiO2 nanoparticles, the prepared composite membrane exhibited excellent comprehensive properties and demonstrated a great potential for various separation applications.

Degradation and toxicity depletion of RB19 anthraquinone dye in water by ozone-based technologies.

This research investigated the discoloration and mineralization of Reactive Blue 19 (RB19) anthraquinone dye by single ozonation, single UV radiation and ozonation jointed with UV radiation (O3/UV). The problem was approached from two points of view: with the objective of color removal or the mineralization of solution. In each case, the optimum operating conditions were different. Ozonation was the most effective treatment for color removal, while the combined O3/UV treatment was for mineralization. Major intermediates of the dye degradation were identified by gas chromatography/mass spectrometry and a degradation pathway was proposed. In addition, a clear decrease of the toxicity of the dye was achieved at the end of the experiments. The effect of initial dye concentration, pH, ozone dose, and UV radiation on the degradation of the dye and decrease of total organic carbon was investigated, in order to establish the optimal operating conditions to achieve discoloration, mineralization or a combination of both.

Enhanced electro-optic response in domain-engineered LiNbO3 channel waveguides

Substantial enhancement (36.7%) of the intrinsic electro-optic coefficient (r33) has been observed in lithium niobate channel waveguides, which are made to overlap with a pole-inhibited ferroelectric domain. The waveguide and the overlapping ferroelectric domain are both produced by a single UV irradiation process and are thus self-aligning. The enhancement of the electro-optic coefficient effect is attributed to strain, which is associated with the ferroelectric domain boundaries that contain the channel waveguide.

Characterization of UV-curable poly(ethylene glycol) diacrylate based hydrogels

Poly(ethylene glycol) diacrylate/polyvinyl alcohol(PEGDA/PVA) hydrogels were prepared from PEGDA and PVA as precurors by means of single UV radiation(UV ra.), UV radiation followed by high energy electron beam irradiation(Irra.), UV radiation followed by freeze-thawing(FT) or UV ra. and Irra. followed by FT, respectively. 2-Hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone(Irgacure 2959) was used as a photoinitiator. The effects of the various methods on the swelling and mechanical properties of the hydrogels were investigated. The results show that hydrogels made by UV ra. plus high energy electron beam irradiation followed by FT showed a higher crosslinking density and a larger tensile strength than those made by the other methods.

Pt deposited TiO2 films with exposed {0 0 1} facets for photocatalytic degradation of a pharmaceutical pollutant

TiO2 films with exposed {001} facets and uniform Pt nanoparticles on the crystal facets were fabricated on a Ti substrate using a simple low temperature electrostatic self-assembly method. Proper Pt colloidal pH value was selected by determining ξ potential of Pt NPs and TiO2 film with exposed {001} facets. Ultra high-resolution FESEM observation shows that Pt NPs with diameter of 2–4nm were physically separated and dispersed on TiO2 facets. The Pt NPs were found to be apt to deposit on the {101} facet with more positive surface potential of TiO2 film and the mean size and the number density of Pt NPs on different facet could be rationally tailored by controlling immersion time of TiO2 film with exposed {001} facets. The Pt-TiO2 film with exposed {001} facets prepared at immersion time of 5min shows considerably higher UV photocatalytic activity than TiO2 film with exposed {001} facets and single UV irradiation for all the experimented initial ethenzamide concentrations, and also no deactivation was observed during 3 recyling runs. The UV photocatalysis employing Pt-TiO2 film with exposed {001} facets as photocatalyst shows significant potential for application in degradation of pharmaceutical and personal care products (PPCPs) with amide bonds.

ZnO nanorods for efficient third harmonic UV generation

ZnO nanorods grown by both high temperature vapour phase transport and low temperature chemical bath deposition are very promising sources for UV third harmonic generation. Material grown by both methods show comparable efficiencies, in both cases an order of magnitude higher than surface third harmonic generation at the quartz-air interface of a bare quartz substrate. This result is in stark contrast to the linear optical properties of ZnO nanorods grown by these two methods, which show vastly different PL efficiencies. The third harmonic generated signal is analysed using intensity dependent measurements and interferometric frequency resolved optical gating, allowing extraction of the laser pulse parameters. The comparable levels of efficiency of ZnO grown by these very different methods as sources for third harmonic UV generation provides a broad suite of possible growth methods to suit various substrates, coverage and scalability requirements. Potential application areas range from interferometric frequency resolved optical gating characterization of few cycle fs pulses to single cell UV irradiation for biophysical studies.

Study on Marine Bacteria Inactivation by UV Radiation Combined with Multi-pore Ceramic Filtration

AbstractUV is one of well-established ways to deal with bacteria in water. However, when applying on marine bacterium inactivation in ballast water, it shows low efficiency due to the existence of large amounts of plankton. To recover high transmission rate of seawater, plankton are required to be removed before UV radiation. Considering technical and economic feasibility, a novel method of multi-pore ceramic filtration (MPCF) is used as a primary treatment before UV radiation. The study compared UV treatment with MPCF & UV treatment at different flow rates and alga concentrations. The results showed that less than 40% marine bacteria can be inactivated by single UV radiation for the existence of large amounts of algae, while up to 100% inactivation rates were observed by MPCF & UV treatment at high alga concentration. According to the results of orthogonal tests, optimal experimental conditions including UV dose were detected. With the combination of MPCF, lethal UV dose for marine bacteria inactivation can reduce to 8 mW·s·cm

Origin of UV Sensitivity of SiON Film and Bidirectional UV Trimming of SiON Microring Resonator

We discovered a photoluminescence phenomenon of SiON waveguide by the UV irradiation and investigated the luminescence spectrum by a conventional microscope and diffraction grating spectroscopy. It was shown from these measurements that the defect created by UV irradiation causes the UV sensitivity of SiON film after thermal annealing. Next, we measured the spectrum change of a microring resonator with SiON core via single point long time UV irradiation and multi point UV irradiation. As a result, we demonstrated a selective UV trimming of microring resonator combining thermal annealing and multi point UV irradiation.

Prevention of the ultraviolet effects on clinical and histopathological changes, as well as the heat shock protein-70 expression in mouse skin by topical application of algal UV-absorbing compounds

Sunscreens have long been used to protect against the acute effects of UV radiation. They can also have protective effects on chronic UV-induced changes, such as photoaging and skin cancer. Recent studies have focused on marine organisms as a source of natural bioactive molecules and some UV-absorbing algal compounds are under investigation as candidates for new natural sunscreens. The cutaneous photoprotective ability of the mycosporine-like aminoacids (MAAs) Porphyra-334 and shinorine (P-334+SH), high UV-absorbing compounds isolated from the red alga Porphyra rosengurttii, was evaluated by in vivo procedures in mouse skin. The expression of the heat shock protein HSP70 as a potential biomarker for acute UV damage was also investigated. A galenic formulation containing the MAA combination of P-334+SH was applied topically to the dorsal skin of SkhR-1 H hairless mice, which were irradiated with a single UV radiation dose of 3.87Jcm(-2) and compared with a combination of UVB- and UVA-absorbing reference filters. Clinical signs of sunburn, such as erythema and edema, as well as other quantifiable histological and biochemical parameters, such as the expression of the heat shock protein 70 and antioxidant enzyme activities, were measured from skin biopsies at 6, 24, 48 and 72h post-radiation. The formulation containing MAA prevented sunburn cell formation, as well as corneum stratum, malphigian, dermal and hypodermal thickening and other structural and morphological alterations observed in biopsies of non-photoprotected skin. A significant increase in Hsp70 was observed in the epidermis of non-photoprotected mouse skin, besides a de novo expression in deeper layers. P-334+SH protected against the significant decrease in superoxide dismutase and catalase activities observed in non-photoprotected mice. The topical application of P-334+SH protected against UV-induced skin damage in mice and contributed to maintaining the antioxidant defence system of the skin as well as Hsp70 expression.

Cyclobutane pyrimidine dimer formation and p53 production in human skin after repeated UV irradiation

Substantial differences in DNA damage caused by a single UV irradiation were found in our previous study on skin with different levels of constitutive pigmentation. In this study, we assessed whether facultative pigmentation induced by repeated UV irradiation is photoprotective. Three sites on the backs of 21 healthy subjects with type II-III skin were irradiated at 100-600 J/m(2) every 2-7 days over a 4- to 5-week period. The three sites received different cumulative doses of UV (1900, 2900 or 4200 J/m(2)) and were biopsied 1 day after the last irradiation. Biomarkers examined included pigment content assessed by Fontana-Masson staining, melanocyte function by expression of melanocyte-specific markers, DNA damage as cyclobutane pyrimidine dimers (CPD), nuclear accumulation of p53, apoptosis determined by TUNEL assay, and levels of p21 and Ser46-phosphorylated p53. Increases in melanocyte function and density, and in levels of apoptosis were similar among the 3 study sites irradiated with different cumulative UV doses. Levels of CPD decreased while the number of p53-positive cells increased as the cumulative dose of UV increased. These results suggest that pigmentation induced in skin by repeated UV irradiation protects against subsequent UV-induced DNA damage but not as effectively as constitutive pigmentation.

The Human Papillomavirus Type 8 E2 Protein Induces Skin Tumors in Transgenic Mice

Transgenic mice expressing early genes of the cutaneous human papillomavirus 8 (HPV8) spontaneously develop skin papillomas, epidermal dysplasia, and squamous cell carcinoma (6%). As the HPV8 protein E2 revealed transforming capacity in vitro, we generated three epidermal specific HPV8-E2-transgenic FVB/N mouse lines to dissect its role in tumor development. The rate of tumor formation in the three lines correlated with the different E2-mRNA levels. More than 60% of heterozygous line 2 mice, but none of the HPV8-negative littermates, spontaneously developed ulcerous lesions of the skin over an observation period of up to 144 weeks, beginning on average 74+/-22 weeks after birth. Most lesions presented infundibular hyperplasia and acanthosis combined with low-grade dysplasia. Severe dysplasia of the epidermis occurred in 6%. Two carcinomas revealed a sharply demarcated spindle-cell component. Only 3 weeks after a single UV irradiation, 87% of heterozygous line 2 and 36% of line 35 mice developed skin tumors. A rapidly growing invasive tumor composed of spindle cells arose 10 weeks after irradiation of a line-35 animal. The histology of skin cancers in HPV8-E2 mice is reminiscent of a subset of highly aggressive squamous cell carcinoma in immunosuppressed transplant recipients with a massive spindle-cell component.

Efficiency of the UV/H2O2 process for the disinfection of humic surface waters

The efficiency of the UV/H2O2 process for the disinfection of total coliforms and the prevention of bacterial regrowth in humic surface waters were investigated. Inactivation of total coliforms was determined in water samples containing various concentrations ranging from 0–10 mg/L dissolved organic carbon (DOC) of fulvic acid, which were exposed to various doses (68–681 mWs/cm2) of UV radiation in the presence of 0.125 mg/L and 3.000 mg/L of hydrogen peroxide. Disinfection efficiencies of the UV radiation and the UV/H2O2 processes were compared. The results of bacterial inactivation experiments showed that the performances of the UV and the UV/H2O2 (0.125) were comparable whereas the UV/H2O2 (3.000) process showed significant improvement in performance, especially, in highly humic waters. Inactivation coefficient appeared to be almost doubled by the addition of 3.000 mg/L hydrogen peroxide during the treatment of highly humic waters. In contradiction to significant regrowth which occurred in the single UV radiation treatment, residual bacteria following the UV/H2O2 (0.125) and the UV/H2O2 (3.000) treatments were completely inactivated during dark incubation indicating the elimination of possible bacterial regrowth.

Expression of decorin and collagens I and III in different layers of human skin in vivo: a laser capture microdissection study

Extracellular matrix (ECM) organization is a complex process that requires the coordinated efforts of many molecules. For the regulation of collagen fiber diameter, the proteoglycan decorin appears to be of major relevance. To investigate the role of decorin in the process of (photo-)aging in more detail, full-thickness punch biopsies were isolated from human buttock skin. Single exposure with two minimal erythemal doses of solar simulated irradiation caused down-regulation of decorin mRNA in young (n = 5) and old subjects (n = 5) after 24 h. Interestingly, decorin mRNA was elevated with age. To test the hypothesis that a decreased collagen-to-decorin-ratio impairs collagen structure we also investigated collagens I and III gene expression. Both were down-regulated with increasing age and after single UV-irradiation. As determined by laser capture microdissection-quantitative real time-Polymerase chain reaction (n = 11), decorin is mostly present in the reticular dermis while being absent from the papillary dermis. Minor expression was also observed in the epidermis. However, in contrast to full-thickness skin biopsies age-dependent changes in collagens I, III, and decorin expression could not be observed with this methodology indicating technical limitations. Together with our finding that collagens I and III mRNA are similarly expressed in the reticular and papillary dermis and are down-regulated by UV, our studies support the idea of a major role of decorin in ECM organization. Altered expression of decorin mRNA in the different dermal strata and a decrease in the collagen-to-decorin ratio inflicted by both age and ultraviolet irradiation possibly affect collagen bundle diameter and subsequently the mechanical properties of human skin.

Oxidation of Acetovanillone by Photochemical Processes and Hydroxyl Radicals

Acetovanillone [Ethanone, 1-(4-hydroxy-3-metoxyphenyl)] is one of the major pollutants that is present in the wastewater produced during the boiling of raw material in the cork industry. The oxidation of its aqueous solutions by monochromatic UV radiation alone and combined with hydrogen peroxide, Fenton's reagent and the photo-Fenton system has been investigated. In the single UV radiation process, the apparent rate constants and the quantum yields are determined, and in the UV/H2O2combination, the additional efficiency in the oxidation process due to the presence of hydrogen peroxide is established. The influence of some operating variables, such as initial concentrations of H2O2 and Fe(II), as well as the pH, is discussed in the Fenton and photo-Fenton systems, and the partial contribution of the radical pathways to the global oxidation rates are evaluated. The rate constant for the reaction of acetovanillone with hydroxyl radicals is also determined by means of a competition kinetics model, its value being 5.62× 109 M−1s−1. Finally, chemical oxidation experiments of wastewaters generated in this industry were carried out by using the same advanced oxidation processes. Specifically, the elimination of acetovanillone in these effluents was determined, and the removal of the global organic pollutant content was also evaluated.

Gallic acid degradation in aqueous solutions by UV/H 2O 2 treatment, Fenton's reagent and the photo-Fenton system

Gallic acid (3,4,5-trihydroxybenzoic acid) is a major pollutant present in the wastewater generated in the boiling cork process, as well as in other wastewaters from food manufacturing industries. Its decay in aqueous solutions has been studied by the action of several oxidation systems: monochromatic UV radiation alone and combined with hydrogen peroxide, Fenton's reagent and the combination Fenton's reagent with UV radiation (photo-Fenton system). The influence of the pH is discussed and the quantum yields are determined in the UV radiation system. Also, the influence of operating variables (initial concentrations of H 2O 2 and Fe(II), and pH) is established in the Fenton's reaction. The apparent pseudo-first-order rate constants are evaluated in all the experiments conducted in order to compare the efficiency of each one of the processes. Increases in the degradation levels of gallic acid are obtained in the combined processes in relation to the single UV radiation system, due to reactions of the very reactive OH . These improvements are determined in every process by calculating the partial contribution to the overall decomposition rate of the radical pathways. For the oxidant concentrations applied, the most effective process in removing gallic acid was found to be the photo-Fenton system. The rate constant for the reaction of gallic acid with OH was also determined by means of a competition kinetics model, being its value 11.0 ± 0.1 × 10 9 l mol −1 s −1.

Organic matter removal from wastewaters of the black olive industry by chemical and biological procedures

Chemical treatments of wastewaters from the olive industry are conducted by means of single UV radiation and by the action of hydroxyl radicals, which are generated by the simultaneous presence of UV radiation and hydrogen peroxide, Fe 2+ and hydrogen peroxide (Fenton system) and Fe 2+ and hydrogen peroxide plus UV radiation (photo-Fenton system). The single photochemical process produces a 35% removal of organic matter present measured as COD after 6 h of reaction, while the hydroxyl radicals enhance significantly this reduction with values in the range 41–76%. At the same time, a removal of aromatic compounds in the oxidation by single UV radiation and combined UV+H 2O 2 was obtained in the range 20–52%. In the anaerobic digestion process, an organic matter reduction in the range 0.77–0.65 g of COD degraded per g of COD fed to the reactor was obtained, and a value of 250 ml CH 4 · g COD −1 obtained for the methane yield coefficient. A kinetic study was conducted using the Monod model, and rate constants k o in the range 0.061–0.015 min −1 achieved. This indicates that some inhibition effects by substances present take place. The application of the Levesnpiel model for that inhibitory effect leads to the determination of the rate constant, inhibitory parameter and critical substrate concentration of inhibition, their values being k=0.205 min −1, n=18.8 and S*=20.1 g l −1 respectively. Finally, the anaerobic digestion of the chemically pretreated wastewaters increases the rate constant k o, as well as the methane yield coefficient, its value being 282 ml CH 4 · g COD −1.

DNA repair of a single UV photoproduct in a designed nucleosome

Eukaryotic DNA repair enzymes must interact with the architectural hierarchy of chromatin. The challenge of finding damaged DNA complexed with histone proteins in nucleosomes is complicated by the need to maintain local chromatin structures involved in regulating other DNA processing events. The heterogeneity of lesions induced by DNA-damaging agents has led us to design homogeneously damaged substrates to directly compare repair of naked DNA with that of nucleosomes. Here we report that nucleotide excision repair in Xenopus nuclear extracts can effectively repair a single UV radiation photoproduct located 5 bases from the dyad center of a positioned nucleosome, although the nucleosome is repaired at about half the rate at which the naked DNA fragment is. Extract repair within the nucleosome is >50-fold more rapid than either enzymatic photoreversal or endonuclease cleavage of the lesion in vitro. Furthermore, nucleosome formation occurs (after repair) only on damaged naked DNA (165-bp fragments) during a 1-h incubation in these extracts, even in the presence of a large excess of undamaged DNA. This is an example of selective nucleosome assembly by Xenopus nuclear extracts on a short linear DNA fragment containing a DNA lesion.

Simultaneous photodegradation and ozonation plus UV radiation of phenolic acids—major pollutants in agro-industrial wastewaters

The degradation of four phenolic acids by single UV radiation and by the advanced oxidation process constituted by the combination of ozone and UV radiation has been conducted. The phenolic acids, caffeic, p-coumaric, syringic and vanillic, were selected because they are major pollutants which are present in wastewaters from the production of olive oil and from wine distillery plants. In the single photochemical oxidation, the influence of the operating variables is established and the quantum yields for each individual reaction are evaluated by means of a competitive kinetic method. In the combined ozone/UV radiation process, the generation of the hydroxyl radicals improves the degradation rate in comparison to the single oxidations performed: ozonation and UV photodegradation. ©1997 SCI

One single erythemagenic UV irradiation is more effective in increasing the proliferative activity of melanocytes in melanocytic naevi compared with fractionally applied high doses.

The effect of a single irradiation with UV light on the expression of Ki67 antigen, topoisomerase II alpha, proliferating cell nuclear antigen (PCNA), the melanocyte activation marker HMB-45 and protein p53 in melanocytic naevi was investigated 1 week after application of a single erythemagenic UV dose and after daily exposures with suberythemagenic doses over 4-6 weeks. To assess the effect of UV irradiation, one half of each naevus was shielded with black tape during the UV exposure, and the irradiated part and the non-irradiated parts were evaluated separately. Except for HMB-45, a double staining procedure was performed to distinguish between labelled melanocytes and keratinocytes. After semiquantitative assessment of the staining signal the irradiated part was compared with the non-irradiated part of the same naevus. Morphological changes and an enhanced proliferative/ reparative activity in melanocytes were much more frequent in the naevi irradiated with a single erythemagenic UV dose than in those given repeated suberythemagenic doses. In addition, the keratinocytes showed an increased labelling for PCNA and p53 after the single irradiation. These data may support the importance of intermittent UV exposure and sunburns in the development of both benign and malignant melanocytic lesions.

Inducible nucleotide excision repair (NER) of UV-induced cyclobutane pyrimidine dimers in the cell cycle of the budding yeast Saccharomyces cerevisiae: evidence that inducible NER is confined to the G1 phase of the mitotic cell cycle.

We previously reported on an inducible component of nucleotide excision repair in Saccharomyces cerevisiae that is controlled by the RAD16 gene. Here we describe a study of this event at the MAT alpha and HML alpha mating-type loci and on the transcribed (TS) and nontranscribed (NTS) strands of the RAD16 gene. Events were examined at various stages of the mitotic cycle in cells synchronised by centrifugal elutriation. Repair of cyclobutane pyrimidine dimers (CPDs) following a single UV dose does not vary significantly in different stages of the mitotic cell cycle. CPDs are removed more rapidly from the transcriptionally active MAT alpha locus than from the silent HML alpha locus, and the TS of RAD16 is repaired faster than the NTS in all stages of the cycle following a single UV irradiation. Enhanced excision of CPDs at MAT alpha and HML alpha can be induced only in the G1 and early S stages of the cell cycle. Here prior irradiation of cells with 25 J/m2 enhances the removal of CPDs following a second UV dose of 70 J/m2. The level of enhancement of repair does not differ significantly between MAT alpha and HML alpha in G1. Enhanced removal of CPDs is absent when cells receive the inducing dose in late S or G2/M. Repair of CPDs in both strands of RAD16 is similarly enhanced only if cells receive the initial irradiation in G1 and early S. The level of enhanced removal of CPDs is not significantly different in the TS and NTS of RAD16 either in asynchronous cells or in cells preirradiated in G1 and early S. It has been shown by others that UV-induced expression of RAD16 remains at high levels if cells are held in G1 by treatment with alpha factor. Therefore the increase in RAD16 transcript levels in G1 may be responsible for the ability to enhance NER solely in this stage of the cell cycle.