Decreasing Radiochromic Film Nonuniformity Errors Using Ultraviolet Rays Exposure

In this chapter, we try to debate two of the most several controversial points about melanoma: the role of the ultraviolet (UV) ray exposure and the position of the sentinel node biopsy in the dermatological daily activity. It has been demonstrated as a direct relationship between UV exposure and the risk of developing melanoma, but it is also true that a chronic continuous UV ray exposure can develop a protective action. Nodal evaluation is one of the most important prognostic indicators to be considered for the patient outcome. The aims for which sentinel node biopsy is so often adopted can be summarized in three points: a detailed nodal staging, a regional disease control, and a possible overall improved survival. At present, many authors do not think that it let the overall survival grow; therefore, they suggest its use only to stage regional lymph nodes and accurately identify patients who could benefit through an early complete regional lymphadenectomy.

The expected life of photovoltaic (PV) modules is 10–20 years as solar modules degrades over the course of time. This degradation is mainly due to the water ingress, ultra violet (UV) rays exposure and temperature stress. The module failure indicators include delamination of the module encapsulation, anti-reflection coating deterioration, discolouration of Ethylene Vinyl Acetate (EVA), glass breakage, open/short circuit failure, hot spot failure and bypass diode failure. The most valuable element utilized in terms of economics is pure silicon, which can be recycled from PV cells. Pure silicon may be recovered from broken or end-of-life PV modules, which can have both financial and environmental advantages. Because of the high purity required of the recovered silicon, chemical treatment is the most critical stage in the recycling process. This work used a variety of etching techniques to etch electric connections, anti-reflective coating and the p–n junction in crystalline-Si(c-Si)-based PV systems which require nitric acid, potassium hydroxide and hydrofluoric acid. Also, the study contains the comparison between thermal and chemical processes availed for the removal of EVA. The thermal process has been performed using a muffle furnace where the samples have been heated at different temperatures 250, 350, 375 and 400 °C at a rate of 15 °C/min. The intact solar cells have been gathered after the heating process and then chemical processes to remove coatings have been performed. Whereas the chemical process for EVA removal required the use of chemical solvents like acetone, ethanol, trichloroethylene and nitric acid in which cells have been immersed. An oven and heat gun has been used to remove the Tedlar sheet. Lastly, the bare silicon wafers obtained from the processes have been collected and tested to confirm the removal.

Fiber-reinforced polymer composites are used as emerging materials to repair oil and gas transmission pipelines without stopping the flow of fluids inside. These pipelines are subjected to harsh environment conditions such as being buried under soil and being exposed to high humidity, high temperatures, and different chemicals. It is important to predict the useful life of composite repairs in these harsh conditions in order to design better and to have robust repair solutions. This study evaluates mechanical properties, namely tensile strength tensile modulus, flexural strength, flexural modulus, and lap shear strength, of composite laminates when exposed to harsh environmental conditions such as hot-wet [70°C/85% relative humidity (RH)] for 0, 2, 4, and 6 weeks, steam autoclave [121°C and 1,05,000 Pa (1.05 bar)] for 0, 6, and 12 h, and ultraviolet (UV) ray exposure of type UVA-340 at 50°C for 0 and 2 weeks. The glass fiber–reinforced polymer (GFRP) composite laminates are prepared by hand layup process and are cut using a water-jet cutting process to avoid machining defects and to keep a good surface finish. The specimens are exposed to these corresponding environmental conditions for different periods of time, and the changes in their mechanical properties are studied. The tensile strength, flexural modulus, and lap shear strength values are compared with unexposed specimens. Decreases in strength and modulus values are observed for exposed specimens. A simple empirical expression is developed to predict the usable lifetime of a composite repair system exposed to such different harsh environmental conditions.

This paper describes the changes of mechanical properties on PEEK after electron beam (EB), atomic oxygen (AO) and ultraviolet ray (UV) exposure under tensile stress. Tensile tests showed that mechanical properties after EB exposure were almost same as those of pristine PEEK. Radiation resistance of PEEK was so high that EB radiation gave no effect on material properties. Although test peace surface was removed by AO attack, tensile strengths after AO exposure were almost same as those of pristine sample. It was clarified that residual strength of PEEK sheet after AO exposure can be estimated by consideration of thickness reduction. PEEK was embrittled by crosslinking resulting from UV radiation. Applied tensile stress during exposure inhibited the crosslinking reaction.

PurposeThe purpose of this study is to understand the mechanism of apoptosis occurring on a cultured human lens epithelial cell line after exposure to ultraviolet (UV) light. We intended to confirm the presence of cellular toxicity and apoptosis and to reveal the roles of p53, caspase 3 and NOXA in these processes.MethodsCells were irradiated with an ultraviolet lamp. Cellular toxicity was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hoechst staining and fluorescent anti-caspase 3 antibodies were used for apoptosis investigation. The quantities of p53, caspase 3, and NOXA were measured by Western blotting for to investigate the apoptosis pathway.ResultsCellular toxicity on the human lens epithelium markedly increased with time after UV exposure. On Hoechst staining, we found that apoptosis also remarkably increased after exposure to ultraviolet light, compared with a control group. In the immunochemical study using anti-caspase 3 antibodies, active caspase 3 significantly increased after exposure to ultraviolet light. On Western blotting, p53 decreased, while caspase 3 and NOXA increased.ConclusionsExposure of cultured human lens epithelial cell lines to ultraviolet light induces apoptosis, which promotes the expression of NOXA and caspase 3 increases without increasing p53. This may suggest that UV induced apoptosis is caused by a p53-independent pathway in human lens epithelial cells.

Background:Ultraviolet (UV) light exposure has been one of the major inducers of apoptosis. UV exposure has caused pyrimidine dimers and DNA fragmentation which might lead to cell cycle arrest and apoptosis signals activation. UV induced apoptosis has investigated in MDA-MB 468 as an ER negative breast adenocarcinoma and MCF-7 as an ER positive breast cancer cell line. Apoptosis induction rate by UV might be different in these two types of cells due to different biological characteristics of the cell.Objectives:In this paper we have evaluated serial dose of UV-B exposure on ER positive and ER negative breast cancer cell lines and its effect on apoptosis or necrosis induction in these cells.Materials and Methods:MDA-MB468 and MCF-7 cell lines have cultured for 24 hours and UV exposure has carried out at 290 nm at dose of 154 J/m2 to 18 KJ/m2 using UV lamp. UV exposed cells have incubated in cell culture condition for 24 or 48 hours following UV exposure and the cells have stained and analyzed by flow cytometry for apoptosis evaluation by Annexin V/PI method.Results:Apoptosis rate (PI and Annexin V double positive cells) after 24 hours incubation was higher in 24 hours in comparison with 48 hours incubation in both cell lines. The frequency of PI positive MDA-MB 468 cells was higher than PI and Annexin V double positive cells after 48 hours. PI positive MDA-MB 468 cells were significantly higher than MCF-7 cells in 24 hours incubation time.Conclusions:The results have shown that MDA-MB 468 cells were more sensitive to UV exposure and DNA fragmentation and necrosis pathway was dominant in these cells.

Measurement of solar ultraviolet (UV) radiation is an important aspect of dosimetry for the improved knowledge of UV exposure and its associated health related issues. EBT2 Gafchromic film has been designed by its manufacturers as an improved tool for ionizing radiation dosimetry. The film is stated as exhibiting a significant reduction in UV response. However, results have shown that when exposed to UV from the ‘bottom side’ i.e. from the thick laminate side, the film exhibits a sensitivity to solar UV radiation which is both measurable and accurate for UV dosimetry. Films were irradiated in this position to known solar UV exposures and results are quantified showing a reproducibility of measurement to within ±7% (1 SD) when compared to calibrated UV meters. With an exposure of 20 J cm−2 broad spectrum solar UV, the films net OD change was found to be 0.248 OD ± 0.021 OD when analysing the results using the red channel region of an Epson V700 desktop scanner. This was compared to 0.0294 OD ± 0.0053 OD change with exposure to the same UV exposure from the top side. This means that solar UV dosimetry can be performed using EBT2 Gafchromic film utilizing the underside of the film for dosimetry. The main advantages of this film type for measurement of UV exposure is the visible colour change and thus easy analysis using a desktop scanner as well as its uniformity in response and its robust physical strength for use in outside exposure situations.

Relationship between the morbidity of pterygium and the duration of ultraviolet rays exposure in Sanya, China

FWT-60 radiochromic film has been tested for colouration effects from fluorescent light sources and shown to produce a marked colouration when exposed to office fluorescent light sources showing an approximate 1 OD unit per 0.5 J m−2 exposure to a broad ultraviolet (UV) UVA + UVB spectrum at the peak absorption wavelength. This produces a measurable and quantifiable response to UV exposure. By choosing an appropriate wavelength of readout or band pass, the level of sensitivity can be changed to match the application or exposure level measurement required. These levels of UV response are significantly higher in sensitivity than other radiochromic films such as Gafchromic MD-55 by an order of magnitude. This feature may be of use for measurement of integrated UV exposure from fluorescent lights when required and produces a quantifiable history of total exposure.

Migration of monomers, plastic additives, and non-intentionally added substances from food utensils made of melamine–formaldehyde resin following ultraviolet sterilization

Evaluation of DNA damage reversal during medium-pressure UV disinfection

Regular exposure of facial skin to sunlight promotes wrinkle formation; ultraviolet (UV) radiation causes the skin to harden and lose its elasticity. To study UV damage to the skin in vitro, a short-term in vitro photoaging model is required. Hence, the UV transmittance of excised human skin was measured. Changes in elasticity in the cheeks of humans of different ages were investigated. Moreover, changes in the hardness and elasticity of collagen gels following UV exposure were investigated. UV rays penetrated the upper layer of the dermis and UVA (330 nm) rays penetrated approximately 1.6 times farther than UVB (310 nm) rays. A correlation between age and lower cheek elasticity was observed. Upon exposure to UV rays, collagen gels hardened and their elasticity decreased; UVA rays exhibited a stronger effect than UVB rays. Wavelengths of 300–340 nm caused hardening and reduced elasticity of collagen gels; 330-nm radiation showed the most pronounced effect. These effects were not observed upon exposure to UV wavelengths over 350 nm. Investigating the UV-hardening mechanism of collagen showed increased tyrosine crosslinks (dityrosines) in the in vitro model of photodamage to collagen, suggesting that dityrosine formation contributes to hardening and reduced elasticity of collagen in photoaged skin.

BackgroundUltraviolet (UV) rays are the major environmental factor that damage skin physiology causing deleterious effects such as oxidation, photoaging and pigmentation. There has been considerable interest in using botanicals to prevent skin damages caused by UV irradiation.AimIn this study, three plant extracts were tested either individually or combined together (mixture) as well as their corresponding main active compound: pomegranate/punicalagin, osmanthus/verbascoside and olive/hydroxytyrosol. We evaluated the whitening and anti-photoaging properties of the nutritional mixture using 2D human culture model and a 3D full-thickness pigmented skin model exposed to UVB and UVA.MethodsFor exploring skin pigmentation, oxidation and aging, we performed cell viability, tyrosinase activity and melanin content assays as well as histology analysis (Whartin–Starry staining), immunodetection (PMEL, MDA, collagen type I and elastin) and carbonylated proteins analysis by electrophoresis separation.ResultsResults showed that the pomegranate extract and the active molecule punicalagin could reduce the tyrosinase activity and melanin content in melanocytes (P < 0.05). The mixture, pomegranate extract and punicalagin inhibited the melanin production and pre-melanosomal protein (PMEL) expression in the 3D skin pigmented model (P < 0.001). Furthermore, the mixture treatment repaired the expressions of collagen I and elastin decrease by UV exposure (P < 0.01). The mixture also significantly decreased lipid peroxidation (P < 0.001) and carbonylated proteins (P < 0.05) in the skin model compared to the UV-exposed condition.ConclusionTo conclude, the mixture composed of pomegranate, osmanthus and olive extracts protects human skin from UV rays deleterious effects and exhibits antioxidative, anti-aging and skin whitening properties. Our data suggested pomegranate contributed to the whitening properties of the mixture notably through its main active compound, punicalagin. The mixture might be a good candidates for further development as natural antioxidant and skin care product.

Modern days, in food industry significant attention has paid to secure food quality, safety and shelf-life. Microbial growth is the major cause of food spoilage which reduces shelf life of food. Food packaging plays a major role in preserving food and maintaining the quality. Food packaging combines with antimicrobial activities are now in demand in food industry due to growing concerns on food quality. As some inorganic nano materials show extensive antimicrobial activity incorporation of them into food packaging exhibit enhanced food quality. These studies have been focused on establishing methods for preparation of antibacterial nano coating for polymer based food packaging. Nanosilver has widely been used in antimicrobial films. For this study nanosilver based polyvinyl alchol coating was prepared on polypropylene food packaging material. Ultra Violet rays were used to contact on the polymer surface in order to enhance the adherence of nano coating to the polypropylene surface. Load required to peel off the nano coating and wetting angles of the modified surface was measured to determine the optimum Ultra Violet rays exposure time. Thermo Gravimetric Analysis (TGA) was used to optimize the crosslinking of the Coating. Presence of nanosilver particles in the developed coating was confirmed by Scanning Electron Microscopy (SEM). The coating was tested against Escherichia coli. The novel nanosilver coated polypropylene food packaging showed significant the antibacterial activity. This developed antimicrobial product can be used to protect the food and reduce the waste in near future.

The goal of this case study was to provide pilot-scale information about the ability of ultraviolet (UV) light to disinfect unfiltered surface water. A pilot-scale (0.25 L/s) UV reactor with low-pressure UV lamps was installed on raw water entering an aqueduct from the Pardee Reservoir at the East Bay Municipal District, California. A pilot monitoring system also collected hourly particle count (2 to 100 m), turbidity, and ultraviolet transmittance (UVT) measurements for 14 months. Grab microbial samples were collected and analyzed for indigenous total coliforms and total aerobic spores (TAS) both before and after UV disinfection, to correlate survival of the organisms across the UV reactor to water quality characteristics. Concentrations of indigenous coliforms and TAS ranged up to 163 and 1,383 per 100 mL respectively, before UV exposure. The data showed that the ability of UV to disinfect coliforms was essentially unaffected by the presence of particles (up to 703&amp;gt;10 m per mL and 1.3 nephelometric turbidity unit [NTU]) in the unfiltered surface water. In 13 of 14 samples, no coliforms were detected in the UV treated water. Log-linear inactivation of TAS up to 2.5-log suggests that at least 99.6% of the TAS were not protected from UV disinfection by particles.