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Although cycling is the most prevalent means of locomotion in the world, little research has been done in evaluating the ultraviolet (UV) radiation exposure of cyclists. In this study, a volunteer using a men's bike was equipped with 10 miniature UV-meters at different body sites. Besides erythemally effective irradiance, the ratio of personal UV exposure to ambient UV radiation was determined for solar elevations up to 65°, taking into account different orientations with respect to the sun. This method provides a universal model that allows for the calculation of UV exposure whenever ambient UV radiation and solar elevation are available. Our results show that the most exposed body sites are the back, forearm, upper arm, and anterior thigh, receiving between 50% and 75% of ambient UV radiation on average. For certain orientations, this percentage can reach 105% to 110%. However, the risk of UV overexposure depends on ambient UV radiation. At lower solar elevations (<40°), the risk of UV overexposure clearly decreases. [ABSTRACT FROM AUTHOR]

This work concerns the new idea of textile printing with a multi-color system using pastes containing compounds sensitive to ultraviolet (UV) radiation. A screen printing method based on a modified CMYK color system was applied to a cotton woven fabric. Aqueous printing pastes were prepared from thickening and crosslinking agents and UV-sensitive compounds: leuco crystal violet (LCV), leuco malachite green (LMG), and 2,3,5-triphenyltetrazolium chloride (TTC) instead of the system's standard process colors: cyan, magenta, and yellow. Depending on the number of printed layers and the type of UV radiation (UVA, UVB, and UVC), the modified textile samples change color after irradiation from white to a wide range of colors (from blue, red, and green to purple, brown, and gray). Based on reflectance measurements, the characteristic parameters of the one-, two-, and three-color-printed samples in relation to absorbed dose were determined, e.g., dose sensitivity, linear and dynamic dose response, and threshold dose. This printing method is a new proposal for UV dosimeters and an alternative standard for textile printing. Furthermore, the developed method can be used for the securing, marking, and creative design of textiles and opens up new possibilities for such stimulus-sensitive reactive printing. [ABSTRACT FROM AUTHOR]

Although cycling is the most prevalent means of locomotion in the world, little research has been done in evaluating the ultraviolet (UV) radiation exposure of cyclists. In this study, a volunteer using a men’s bike was equipped with 10 miniature UV-meters at different body sites. Besides erythemally effective irradiance, the ratio of personal UV exposure to ambient UV radiation was determined for solar elevations up to 65°, taking into account different orientations with respect to the sun. This method provides a universal model that allows for the calculation of UV exposure whenever ambient UV radiation and solar elevation are available. Our results show that the most exposed body sites are the back, forearm, upper arm, and anterior thigh, receiving between 50% and 75% of ambient UV radiation on average. For certain orientations, this percentage can reach 105% to 110%. However, the risk of UV overexposure depends on ambient UV radiation. At lower solar elevations (

The personal ultraviolet (UV) dosimeter is a useful measurement tool to prevent UV induced dermal damages; however, conventional digital dosimeters are either bulky or require external power sources. Here, a wearable, colorimetric UV film dosimeter that provides color transition, from purple to transparent, is reported to indicate the UV dose. The film dosimeter is made of a purple photodegradable dye ((2Z,6Z)-2,6-bis(2-(2,6-diphenyl-4H-thiopyran-4-ylidene)ethylidene)cyclohexanone or DTEC) blended in low density polyethylene film. The DTEC film discolored 3.3 times more under the exposure of UV light (302 nm) than visible light (543 nm), and a UV bandpass filter is developed to increase this selectivity to UV light. The DTEC film completely discolors to transparency in 2 h under an AM 1.5 solar simulator, suggesting the potential as an indicator for individuals with types I-VI skin to predict interventions to avoid sunburn. Finally, the DTEC film is integrated with the UV bandpass filter on a wristband to function as a wearable dosimeter for low cost and convenient monitoring of sunlight exposure.

This work concerns the new idea of textile printing with a multi-color system using pastes containing compounds sensitive to ultraviolet (UV) radiation. A screen printing method based on a modified CMYK color system was applied to a cotton woven fabric. Aqueous printing pastes were prepared from thickening and crosslinking agents and UV-sensitive compounds: leuco crystal violet (LCV), leuco malachite green (LMG), and 2,3,5-triphenyltetrazolium chloride (TTC) instead of the system’s standard process colors: cyan, magenta, and yellow. Depending on the number of printed layers and the type of UV radiation (UVA, UVB, and UVC), the modified textile samples change color after irradiation from white to a wide range of colors (from blue, red, and green to purple, brown, and gray). Based on reflectance measurements, the characteristic parameters of the one-, two-, and three-color-printed samples in relation to absorbed dose were determined, e.g., dose sensitivity, linear and dynamic dose response, and threshold dose. This printing method is a new proposal for UV dosimeters and an alternative standard for textile printing. Furthermore, the developed method can be used for the securing, marking, and creative design of textiles and opens up new possibilities for such stimulus-sensitive reactive printing.

N-channel thin film transistors (TFTs) fabricated with hydrogenated low temperature polycrystalline silicon (LTPS) were exposed to ultraviolet (UV) radiation to a cumulative dose up to 16 J/cm2. The effect of radiation on the electrical characteristics of the devices was monitored after the irradiation steps and in a prolonged period after irradiation. The main monitoring parameter was the threshold voltage ( ${V} _{\mathrm{ th}}$ ) which was found to have exponentially linear dependence on irradiation dose. This, together with obtained low fading, suggests that hydrogenated n-channel low temperature polycrystalline silicon TFTs have potential as UV radiation dosimeters. In addition, the physical mechanisms of the UV induced electrical degradation were analyzed in terms of the radiation generated traps at poly-Si grain boundary and poly-Si and gate oxide insulator (poly-Si/SiO2) interface.

This work reports the use of the slot‐die (SD) coating solution processing method to fabricate large‐area organic thin films composed of photochromic dyes as UV indicators and UV light absorbers as UV filters on polyethylene terephthalate flexible substrates. This is the first demonstration of large‐area SD coated organic photochromic films and UV filters. Impressively, highly uniform photochromic films comprised of small molecules are formed in air, from green solvents (i.e., alcohols) and show rapid color changes upon external stimuli (i.e., light and heat). The UV filters processed under the same conditions and comprised of only small molecules show highly transparent films in the visible and near‐IR range with T% > 97%@550 nm and excellent UV blocking ability. The work highlights the utility of roll‐to‐roll compatible SD‐coating methods to make prototype organic devices in an academic laboratory setting and opens the door for additive manufacturing of simple and low‐cost UV active films for healthcare and electronic applications. [ABSTRACT FROM AUTHOR]

Accurate and low‐cost wearable or portable monitors for personal solar ultraviolet (UV) exposure are of interest to reduce the risk of adverse UV effects such as eye diseases, sunburn and skin cancer. Here, a novel sensor involving the racemization of a chiral dopant within a nematic liquid crystalline matrix is described, and the suitability of these sensors to act as personal UV dosimeters is explored. It was shown that these sensors respond to UV light with a significant change in the position of the reflection band of the chiral nematic liquid crystal. The sensitivity of these sensors is shown to be 0.23 nm/mJcm−2. This corresponds to a change of 80 nm over a dose equivalent to two hours of solar exposure. [ABSTRACT FROM AUTHOR]

Biological warfare and bioterrorism is an unpleasant fact of 21st century life. Highly infectious and profoundly virulent diseases may be caused in combat personnel or in civilian populations by the appropriate dissemination of viruses, bacteria, spores, fungi, or toxins. Dissemination may be airborne, waterborne, or by contamination of food or surfaces. Countermeasures may be directed toward destroying or neutralizing the agents outside the body before infection has taken place, by destroying the agents once they have entered the body before the disease has fully developed, or by immunizing susceptible populations against the effects. A range of light-based technologies may have a role to play in biodefense countermeasures. Germicidal UV (UVC) is exceptionally active in destroying a wide range of viruses and microbial cells, and recent data suggests that UVC has high selectivity over host mammalian cells and tissues. Two UVA mediated approaches may also have roles to play; one where UVA is combined with titanium dioxide nanoparticles in a process called photocatalysis, and a second where UVA is combined with psoralens (PUVA) to produce "killed but metabolically active" microbial cells that may be particularly suitable for vaccines. Many microbial cells are surprisingly sensitive to blue light alone, and blue light can effectively destroy bacteria, fungi, and Bacillus spores and can treat wound infections. The combination of photosensitizing dyes such as porphyrins or phenothiaziniums and red light is called photodynamic therapy (PDT) or photoinactivation, and this approach cannot only kill bacteria, spores, and fungi, but also inactivate viruses and toxins. Many reports have highlighted the ability of PDT to treat infections and stimulate the host immune system. Finally pulsed (femtosecond) high power lasers have been used to inactivate pathogens with some degree of selectivity. We have pointed to some of the ways light-based technology may be used to defeat biological warfare in the future. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine experimentally the effects of the quality (UV-A/UV-B ratio) and quantity (irradiance) of natural ultraviolet radiation (UVR) on the survival of yellow perch ( Perca flavescens) larvae and on the oxidative stress in their cytoplasm, estimated by the activity of the superoxide dismutase (SOD). We also estimated the potential accumulation of photodamage in DNA by using UV dosimeters. Freshly-hatched yellow perch and UV dosimeters were incubated in controlled conditions under a factorial combination of selective and non-selective filters offering different levels of UVR protection and exposed to natural solar light. Larval survival was inversely related to the UVR intensity gradient, and responded similarly to the presence of both UV-A and UV-B or UV-A only. In contrast, the responses of SOD activity and UV dosimeter were stronger in the presence of both UV-A and UV-B than UV-A only, leading to a partial mismatch with the results on survival. Our results, obtained under natural solar light, suggest that incident UV-A radiation, despite its lower energy per unit photon than UV-B, could be a serious threat for yellow perch larvae. They also show that UV dosimeters and SOD activity predict only some components of UVR risk for yellow perch larvae. The partial mismatch between UV dosimeters results and larval survival cautions against the use of UV dosimeters alone as a proxy for UVR risk in the field. [ABSTRACT FROM AUTHOR]