Combination Of Ultraviolet Radiation Research Articles

Ultraviolet disinfection of activated carbon from microbiological contamination

This article aims to investigate the effectiveness of the use of ultraviolet radiation or a combination of ultraviolet radiation and ozonation in the inactivation of microorganisms in activated carbon "Silcarbon". Several experimental studies where ultraviolet light, a combination of UV radiation, and ozonation were used have been performed to disinfect "Silcarbon" from microbiological contaminants. Experimental results have shown that with pulsed xenon lamps and low-pressure mercury ozone lamps, satisfactory results can be obtained in which the total amount of yeast and mould fungi range from 50 CFU/g to 75 CFU/g. It is advisable to continue the study of powder materials, including drugs, on the content of microbiological contaminants to assess their compliance with regulatory requirements. The application of the proposed approach to the inactivation of microorganisms allows one to obtain a safe sorbent on the content of microbiological indicators and can be successfully used in any other field to disinfection powder materials using different modes of UV irradiation. The originality of the article's results proposes a method of disinfection of the sorbent "Silcarbon" from moulds and yeasts for therapeutic purposes in medicine.

Ocular toxicology: synergism of UV radiation and benzalkonium chloride

Purpose To investigate the combined toxic effect of ultraviolet (UV) radiation and benzalkonium chloride (BAK), a common preservative in ophthalmic eye drops, on human corneal epithelial cells (HCEC). Methods Cultured HCEC were exposed to different combined and separate UV (280–400 nm) and BAK solutions at relevant human exposure levels. Human exposure to UV can occur before, during, or after eye drop installation, therefore, three different orders of ocular exposures were investigated: UV and BAK at the same time, UV first followed by BAK, and BAK first followed by UV. Control treatments included testing HCEC exposed to BAK alone and also HCEC exposed to UV alone. In addition, phosphate-buffered saline (PBS) was used as a negative control. After exposure, cell metabolic activity of the cultures was measured with PrestoBlue, and cell viability was determined using confocal microscopy with viability dyes. Results BAK alone reduced the metabolic activity and cell viability of HCEC in a dose- and time-dependent manner. UV alone at a low dose (0.17 J/cm2) had little toxicity on HCEC and was not significantly different from PBS control. However, UV plus BAK showed combined effects that were either greater than (synergistic) or equal to (additive) the sum of their individual effects. The synergistic effects occurred between low dose UV radiation (0.17 J/cm2) and low concentrations of BAK (0.001%, 0.002%, 0.003%, and 0.004%). Conclusions This investigation determined that at relevant human exposure levels, the combination of UV radiation (280–400 nm) and BAK can cause synergistic and additive toxic effects on human corneal epithelial cells. This finding highlights the importance of considering the combined ocular toxicity of BAK and solar radiation in the risk assessment of BAK-preserved ophthalmic solutions.

Degradation of tri(2-chloroisopropyl) phosphate by the UV/H2O2 system: Kinetics, mechanisms and toxicity evaluation

A photodegradation technology based on the combination of ultraviolet radiation with H2O2 (UV/H2O2) for degrading tri(chloroisopropyl) phosphate (TCPP) was developed. In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.0035 min−1 (R2 = 0.9871) for 5 mg L−1 TCPP using 250 W UV light irradiation with 50 mg L−1 H2O2. In detail, the yield rates of Cl− and PO43− reached 0.19 mg L−1 and 0.58 mg L−1, respectively. The total organic carbon (TOC) removal rate was 43.02%. The pH value of the TCPP solution after the reaction was 3.46. The mass spectrometric detection data showed a partial transformation of TCPP into a series of hydroxylated and dechlorinated products. Based on the luminescent bacteria experimental data, the toxicity of TCPP products increased obviously as the reaction proceeded. In conclusion, degradation of high concentration TCPP in UV/H2O2 systems may result in more toxic substances, but its potential application for real wastewater is promising in the future after appropriate optimization, domestication and evaluation.

Removal of Acid Orange 7 dye from wastewater using combination of ultraviolet radiation, ultrasonic method, and MgO nanoparticles

Background: Industrial dyes are toxic and carcinogenic, therefore, they should be removed from wastewater. The aim of this study was to investigate the removal of acid orange 7 Dye from wastewater using ultraviolet (UV) radiation, MgO nanoparticles, ultrasonic method alone and in combination with each other. Methods: The effects of some factors such as temperature, pH, hydraulic retention time (HRT), UV power, and concentration of MgO nanoparticles on the removal of Acid Orange 7 dye from synthetic wastewater using different methods were investigated. Also, adsorption isotherms for MgO nanoparticles and kinetics for UV radiation were investigated. Results: The optimum HRT was 55 minutes while the temperature was not effective in dye removal using the ultrasonic method. Under optimum conditions for UV irradiation method (HRT = 70 minutes, UV power = 170 mW/cm2, and temperature = 10˚C), 58% of the dye was removed. However, under optimum conditions for MgO nanoparticles method (HRT = 15 minutes, temperature = 20˚C, and ratio of MgO nanoparticles to the initial dye concentration = 67.2), 82% of the dye was removed. By combining these methods, the dye removal efficiency was significantly increased. The combination of ultrasonic method and MgO nanoparticles had no significant effect on increasing the dye removal efficiency from wastewater. It was revealed that dye removal using UV radiation can be described by the first-order kinetics. Conclusion: According to the results, UV radiation has a synergistic effect on the dye adsorption process by MgO nanoparticles. Therefore, the combination of these methods can be effective for the removal of dye from wastewater.

Effect of water leaching on photodegraded spruce wood monitored by IR spectroscopy

Spruce samples (Picea abies Karst.) were irradiated by a strong ultraviolet (UV) light emitter mercury lamp, and another series of specimens were treated with the combination of UV radiation and water leaching. The total duration of UV radiation for both series of specimens was 10 days. One treatment cycle consisted of 24 h of UV irradiation, followed by 6 h of water leaching. This cycle was repeated 10 times. The chemical changes were determined by IR spectroscopy, and the difference spectrum method was used for evaluation. The IR measurement was carried out after each UV radiation as well as after water leaching, to determine the effect of UV radiation and water leaching separately. The lignin degradation was more significant for the leached samples than for the pure UV treated samples. The chemical components most sensitive to leaching were the unconjugated carbonyl groups generated by the photodegradation. As a consequence of photodegradation, two absorption bands of unconjugated carbonyl groups emerged at 1714 and 1750 cm−1 wavenumbers. The band at 1750 cm−1 was much more sensitive to leaching by water than the band at 1714 cm−1. This band almost disappeared after eight cycles. The water was able to leach out carbonyl groups (absorbing at 1741 cm−1) that had been present in the wood originally as well.

The effect of domestic laundry detergents on the light fastness of certain reactive dyes on 100% cotton

This study presents findings on the effect of several domestic laundry detergents on the fastness to light of selected fiber reactive dyes applied to cotton. Cotton fabric dyed with commonly used reactive dyes were laundered with water only, several domestic detergents, and a laboratory-formulated neutral detergent, and then exposed to light for 2 h in the wet state. Exposures were repeated 15 times, equivalent to 30 h of exposure. Color loss and color difference were measured after 5, 10, and 15 wash cycles, and 10 h, 20 h, and 30 h of exposure. When the fabric was exposed to light wet, the color faded more rapidly than when it was exposed dry. The presence of an oxidizing bleach (sodium perborate or sodium percarbonate) in the detergent increased color loss during washing and wet exposure to light. Ultraviolet radiation from the light source, heat, moisture, alkali, and oxidizing bleach during exposure resulted in hydrolysis of the dye–fiber bond, causing dye desorption during washing and rinsing. The combination of ultraviolet radiation and oxidizing bleaches altered the chemistry of the dye and hence its shade. This was particularly evident on the black dye and one of the navy blue dyes.

Red tattoos, ultraviolet radiation and skin cancer in mice.

Ultraviolet radiation (UVR) induces skin cancer. The combination of UVR and red tattoos may be associated with increased risk of skin cancer due to potential carcinogens in tattoo inks. This combination has not been studied previously. Immunocompetent C3.Cg/TifBomTac hairless mice (n=99) were tattooed on their back with a popular red tattoo ink. This often used ink is banned for use on humans because of high content of the potential carcinogen 2-anisidine. Half of the mice were irradiated with three standard erythema doses UVR thrice weekly. Time to induction of first, second and third squamous cell carcinoma (SCC) was measured. All UV-irradiated mice developed SCCs. The time to the onset of the first and second tumor was identical in the red-tattooed group compared with the control group (182 vs 186days and 196 vs 203days, P=ns). Statistically, the third tumor appeared slightly faster in the red-tattooed group than in the controls (214 vs 224days, P=.043). For the second and third tumor, the growth rate was faster in the red-tattooed group compared with the control (31 vs 49days, P=.009 and 30 vs 38days, P=.036). In conclusion, no spontaneous cancers were observed in skin tattooed with a red ink containing 2-anisidine. However, red tattoos exposed to UVR showed faster tumor onset regarding the third tumor, and faster growth rate of the second and third tumor indicating red ink acts as a cocarcinogen with UVR. The cocarcinogenic effect was weak and may not be clinically relevant.

Demethoxycurcumin in combination with ultraviolet radiation B induces apoptosis through the mitochondrial pathway and caspase activation in A431 and HaCaT cells.

Photodynamic therapy is widely used in the clinical treatment of tumors, especially skin cancers. It has been reported that the photosensitizer curcumin, in combination with ultraviolet radiation B, induces HaCaT cell apoptosis, and this effect may be due to the activation of caspase pathways. In this study, we examined the photodynamic effects of demethoxycurcumin, a more stable analogue of curcumin, to determine whether it could induce apoptosis in skin cancer cells. We investigated the effects of a combination of ultraviolet radiation B and demethoxycurcumin on apoptotic cell death in A431 and HaCaT cells and determined the molecular mechanism of action. Our results showed increased apoptosis with a combination of ultraviolet radiation B with demethoxycurcumin, as compared to ultraviolet radiation B or demethoxycurcumin alone. The combination of ultraviolet radiation B irradiation with demethoxycurcumin synergistically induced apoptotic cell death in A431 and HaCaT cells through activation of p53 and caspase pathways, as well as through upregulation of Bax and p-p65 expression and downregulation of Bcl-2, Mcl-1, and nuclear factor-κB expression. In addition, we found that reactive oxygen species significantly increased with treatment, and mitochondrial membrane potential depolarization was remarkably enhanced. In conclusion, our data indicate that demethoxycurcumin may be a promising photosensitizer for use in photodynamic therapy to induce apoptosis in skin cancer cells.

Patterning of Solid Films via Selective Atomic Layer Deposition Based on Silylation and UV/Ozonolysis.

A simple methodology was successfully demonstrated for the nanoscale patterning of silicon wafers. Thin films are grown by atomic layer deposition (ALD) and patterned by using selective surface chemistry: First, all the nucleation sites on the original oxide surface are silylated in order to render them unreactive; then, a pattern is developed by selective removal of the silylation agent using a mask and a combination of ultraviolet radiation and ozonolysis. Subsequent ALD is carried out selectively on the areas where the silylation moieties have been removed. This simple procedure affords patterning of oxide surfaces with monolayer control and a lateral resolution on the order of a few tens of nanometers or better. Other selective ALD processes have shown only limited discrimination during deposition, but our method shows absolute inhibition of film growth on the silylated areas while films as thick as 10 nm are grown on the re-exposed sectors. Our example involved the deposition of hafnium oxide films on the native silicon oxide film that forms on Si(100) wafers, but we believe that the approach is general and easily extendable to other ALD processes.

Impact of Climatic Ageing on the Basic Mechanical Properties of Viscoelastic Sealants

The aim of the research presented here was to assess the influence of climatic loading on the basic mechanical properties of polymer sealants, from the viewpoint of their application in creating and repairing outdoor mosaics. Six promising sealants were selected for the measurements. They were tested in their native state and also after four different model types of physical-chemical ageing were applied. We used a combination of ultra-violet radiation with the influence of enhanced temperature, moisture and also soaking in water and freezing. The Hysitron TI 750D TriboIndeterTM system, equipped with a Berkovich indenter, was used for tests. The basic mechanical characteristics were measured using the Basic QS Trapezoid quasi-static mode. Time-dependent properties of the sealants were assessed by the indentation creep method. The results have confirmed that microindentation technique offers a suitable methodology for assessing changes in the basic mechanical time-dependent properties of the tested sealants due to photo-degradation processes and climatic effects.

Modeling optimal process conditions for UV-heat inactivation of foodborne pathogens in liquid foods

The combination of ultraviolet radiation and heat (UV-H treatment) has been demonstrated as a promising strategy to overcome the limited UV germicidal effect in fruit juices. Nonetheless, there are so far no data regarding the efficacy of the combined process for the inactivation of bacterial foodborne pathogens in other liquid foods with different pH and composition. In this investigation, the optimum UV-H processing conditions for the inactivation of Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and S. aureus in chicken and vegetable broth, in addition to juices, were determined. From these data models that accurately predict the most advantageous UV-H treatment temperature and the expected synergistic lethal effect from UV and heat resistance data separately were constructed. Equations demonstrated that the optimum UV-H treatment temperature mostly depended on heat resistance, whereas the maximum synergistic lethal effect also was affected by the UV resistance of the microorganism of concern in a particular food.

Evaluation of ultraviolet ageing, pollution and varistor degradation effects on harmonic contents of surge arrester leakage current

Metal-oxide surge arresters are one of the most important equipments for power system protection against switching and lightning over-voltages. Surge arresters leakage currents increase by the operating time. In this study, the important factors on leakage current variations such as surface contamination, ultraviolet ageing and varistor degradation have been studied. To accomplish this purpose, experimental tests have been performed on various polymer housed surge arresters. Fast Fourier transform analysis has been performed on measured leakage currents. Results show that ultraviolet radiation and varistor degradation affect resistive harmonic components, especially the third and fifth harmonics. Moreover, it is observed that surface contamination has influence on fundamental harmonic variation more than ultraviolet ageing. In addition, combination of ultraviolet radiation and pollution had more effect on leakage currents. The investigation and the discussion of the results can be used to easily analyse arresters condition leading to effective schedule maintenance.

Black tattoos protect against UVR-induced skin cancer in mice.

Black tattoos may involve risk of cancer owing to polycyclic aromatic hydrocarbons including benzo(a)pyrene (BaP) in inks. Ultraviolet radiation (UVR) induces skin cancer. The combination of UVR and black tattoo maytherefore potentially be very problematic, but has not been previously studied. Immunocompetent C3.Cg/TifBomTac mice (n=99) were tattooed on the back with Starbrite Tribal Black(™) . This ink has a high content of the carcinogen BaP. Half of the mice were irradiated with three standard erythema doses UVR thrice weekly. Time to induction of first, second and third squamous cell carcinoma (SCC) was measured. Controls were 'tattooed' without ink. All irradiated mice developed SCCs while no malignant tumours were found in the nonirradiated group. In the tattooed and irradiated group, the development of the first, second and third SCC was significantly delayed in comparison with the irradiated controls without black tattoos (212, 232, 247days vs. 163, 183, 191days, P<0.001). In UVR-irradiated black tattoos, remarkably, the development of UVR-induced skin cancer was delayed by the tattoos. Skin reflectance measurement indicated that the protective effect of black pigment in the dermis might be attributed to UVR absorption by black pigment below the epidermis and thereby reduction of backscattered radiation.

Skin temperature during sunbathing—relevance for skin cancer

It has been found that exposure to heat and infrared radiation (IR) can be carcinogenic, and that a combination of ultraviolet radiation (UVR) and IR possibly amplifies carcinogenesis. To investigate how the skin temperature is affected by sunbathing, we measured the skin temperature on 20 healthy volunteers over 6 days' sun holiday in Egypt. Temperatures were measured with an infrared thermometer gun at 8 skin sites on the volunteers while they were indoors in the morning and when sunbathing during the day. Skin temperatures were higher during sunbathing (33.5 °C ± 2.1 °C) (mean ± SD) than when indoors in the morning (32.6 °C ± 1.4 °C) (mean ± SD) (P < 0.0001). The average skin temperature for men was higher than for women by 0.40 °C in the morning (P = 0.02) and by 0.44 °C during sunbathing (P < 0.0001). Our results show that sunbathing has an impact on skin temperature, which possibly by activation of the heat shock response, is likely to contribute to the immediate and delayed effects of UV in a way that has to be found out in future studies.

Photodegradation of Tri(Chloropropyl) Phosphate Solution by UV/O3

A photodegradation technology based on the combination of ultraviolet radiation with ozone (UV/O3) for degrading tri(chloropropyl) phosphate (TCPP) was developed in the present study. Parameters affecting the degradation of TCPP were optimized, and the developed technology was successfully applied to degrade TCPP in two real wastewater samples. The results showed that reaction time, ozone concentration, the initial acidity of reaction solution, and the initial concentration of TCPP in aqueous solution contributed to the degradation efficiency of TCPP. Under the optimized disposal conditions, 100 mg/L of TCPP aqueous solution with a pH value of 7 can be degraded effectively in 60 min with an ozone concentration of 66.2 mg/L. In detail, the yield rates of Cl− and PO4 3− was high up to 98.9 and 98.2 %, respectively; and total organic carbon (TOC) removal rate was high up to 94.3 %. Method application demonstrated that TCPP can be degraded effectively in pond water. However, only 83.2 and 61.9 % of Cl− and PO4 3− were produced, and the TOC removal rate was only 81.3 % after 60 min exposure in the effluent discharged from a wastewater treatment plant. Therefore, the presence of interferences may hinder the degradation of TCPP in real wastewater, but its potential application for real wastewater is promising in the future after appropriate domestication and evaluation.

Differential Responses of Two Phytoplankton Communities from the Chubut River Estuary (Patagonia, Argentina) to the Combination of UVR and Elevated Temperature

Fil: Helbling, Eduardo Walter. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Fundacion Playa Union. Estacion de Fotobiologia Playa Union; Argentina

Induction of Primary Cutaneous Melanomas in C3H Mice by Combined Treatment with Ultraviolet Radiation, Ethanol and Aloe Emodin ¶

The role of ultraviolet (UV) radiation in the induction of nonmelanoma skin cancer is widely accepted, although its precise contribution to the development of primary cutaneous melanoma skin cancer requires further definition. We found that painting aloe emodin, a trihydroxyanthraquinone from Aloe barbadensis, in ethyl alcohol vehicle on the skin of mice in conjunction with exposure to UVB (280–320 nm) radiation results in the development of melanin-containing skin tumors. C3H/HeN mice were treated thrice weekly with aloe emodin in a 25% ethanol in water vehicle and exposed to 15 kJ/m2 UV radiation. Neither ethanol vehicle nor aloe emodin alone induced skin tumors in the absence of UV radiation. In two separate experiments, 20–30% of the mice treated with a combination of UV radiation and ethanol vehicle and 50–67% of the UV-irradiated animals given aloe emodin in ethanol vehicle developed primary cutaneous melanin-containing tumors. The diagnosis of melanoma was established using Fontana silver stain for melanin; these tumors were negative for vimentin and keratin. Melanin-containing melanosomes were observed by transmission electron microscopy in tumors diagnosed as melanomas. Although the mechanism of carcinogenesis in these mice is currently unknown, our findings have led to the development of the first facile murine model for the induction of primary melanoma. This model has the potential to clarify the role of UV radiation in the etiology of malignant melanoma.

Cancer chemopreventive effects of Pinus Maritima bark extract on ultraviolet radiation and ultraviolet radiation-7,12,dimethylbenz(a)anthracene induced skin carcinogenesis of hairless mice

The bark extract of Pinus Maritima (PBE), a rich in phenolic acids, polyphenols and in particular flavonoids mixture, was examined for skin cancer preventive action that was evaluated in two different experimental animal tumor models induced by ultraviolet radiation (UVR) and combination of UVR with 7,12-dimethylbenz[a]anthracene. Significant decrease in the number of animals bearing tumors and the number of tumors per animal was observed in the PBE treated animals. In the same time significant increase in the viability of these animals was also observed. Furthermore, PBE delayed the appearance of tumors. These results provide strong evidence about the preventive anticancer activity of this extract on non-melanoma skin cancer and its protective effect not only from UVR, but also from more potent carcinogenic agents.

Exposure to chromium (VI) in the drinking water increases susceptibility to UV-induced skin tumors in hairless mice

Hexavalent chromium (Cr (VI)) is a well known-human carcinogen with exposures occurring in both occupational and environmental settings. Although lung carcinogenicity has been well documented for occupational exposure via inhalation, the carcinogenic hazard of drinking water exposure to Cr (VI) has yet to be established. We used a hairless mouse model to study the effects of K 2CrO 4 in the drinking water on ultraviolet radiation (UVR)-induced skin tumors. Hairless mice were unexposed or exposed to UVR alone (1.2 kJ/m 2), K 2CrO 4 alone at 2.5 and 5.0 ppm, or the combination of UVR and K 2CrO 4 at 0.5, 2.5, and 5.0 ppm. Mice were observed on a weekly basis for the appearance of skin tumors larger than 2 mm. All the mice were euthanized on day 182. The skin tumors were excised and subsequently analyzed microscopically for malignancy by histopathology. There was a total absence of observable skin tumors in untreated mice and in mice exposed to chromate alone. However, there was a dose-dependent increase in the number of skin tumors greater than 2 mm in mice exposed to K 2CrO 4 and UV compared with mice exposed to UV alone. The increase in tumors larger than 2 mm was statistically significant ( P < 0.05) for UV and K 2CrO 4 at the two highest K 2CrO 4 doses (2.5 and 5.0 ppm), and there was a statistically significant increase in the numbers of malignant tumors per mouse in the UVR plus K 2CrO 4 (5 ppm) group compared with UV alone. The data presented here indicate that K 2CrO 4 increases the number of UV-induced skin tumors in a dose-dependent manner, and these results support the concern that regulatory agencies have relative to the carcinogenic health hazards of widespread human exposure to Cr (VI) in drinking water.

Effects of mobile phone radiation on UV-induced skin tumourigenesis in ornithine decarboxylase transgenic and non-transgenic mice

Purpose: The effects of low-level radiofrequency radiation (RFR) on ultraviolet (UV)-induced skin tumorigenesis were evaluated in ornithine decarboxylase (ODC) and non-transgenic mice.Materials and methods: Transgenic female mice over-expressing the human ODC gene and their non-transgenic littermates (20 animals in the cage control group, and 45-49 animals in the other groups) were exposed for 52 weeks to UV radiation or a combination of UV radiation and pulsed RFR. The UV dose was 240 Jm−2 (1.2 ×human minimum erythemal dose) delivered three times a week. One group of animals was exposed to Digital Advanced Mobile Phone System (DAMPS)-type RFR, the other group to Global System for Mobile (GSM)-type RFR at a nominal average specific absorption rate of 0.5 W kg−1, 1.5 h day−1, for 5 days a week. The skin was carefully palpated weekly for macroscopic tumours. Histopathological analyses of all skin lesions and of a specified dorsal skin area were performed on all animals.Results: UV exposure resulted in development of macroscopic skin tumours in 11.5 and 36.8% of non-transgenic and transgenic animals, respectively. The RFR exposures did not give a statistically significant effect on the development of skin tumours in either transgenic or non-transgenic animals, or in combined analysis, but tumour development appeared slightly accelerated especially in non-transgenic animals. No effects of RFR exposures were found on excretion of 6-hydroxymelatonin sulphate into urine or on polyamine levels in dorsal skin.Conclusion: RFR exposures did not significantly enhance skin tumourigenesis. However, the slightly accelerated tumour development may warrant further evaluation.