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This work reports on radiochromic dosimeters for 1D UV light measurements. The dosimeter is composed of a 25% Pluronic F–127 that forms a physical gel matrix and nitro blue tetrazolium chloride (NBT) as a radiation-sensitive compound. This dosimeter was exposed to UVA, UVB and UVC radiation, and the radiochromic reactions were followed with reflectance spectrophotometry including changes in light reflectance and color coordinates in the CIELAB color system. The exposition of dosimeters to all UV radiation caused color changes from pale yellow to dark violet, and its intensity increased with increasing absorbed dose. The effects of NBT concentration and UV radiation type on the dose–response of the dosimeters were also examined. The results obtained reveal that the dosimeters are the least sensitive to irradiation with UVC and the most sensitive to irradiation with UVB (e.g., dosimeter with 2 g/dm3 of NBT was characterized by the following parameters: the threshold dose 0.1 J/cm2; the dose sensitivity −5.97 ± 0.69 cm2/J; the linear dose range 0.1–2.5 J/cm2; the dynamic dose range was equal to 0.1–3 J/cm2). The results obtained reveal that the NBT–Pluronic F–127 dosimeters can be potentially useful as 1D sensors for artificial UV radiation sources measurements.

The oceans are taking up over one million tons of fossil CO 2 per hour, resulting in increased p CO 2 and declining pH, leading to ocean acidification (OA). At the same time, accumulation of CO 2 and other greenhouse gases is causing ocean warming, which enhances stratification with thinned upper mixed layers, exposing planktonic organisms to increasing levels of daytime integrated UV radiation. Ocean warming also reduces dissolved oxygen in seawater, resulting in ocean deoxygenation. All these ocean global changes are impacting marine ecosystems and effects are well documented for each individual driver (pH, oxygen, temperature, UV). However, combined effects are still poorly understood, strongly limiting our ability to project impacts at regional or local levels. Different regions are often exposed (and often adapted) to contrastingly different physical and chemical environmental conditions and organisms, and ecosystems from different parts of the world will be exposed to unique combinations of stressors in the future. Understanding the modulating role of adaptation, species niche and stressors’ interaction is key. This review, being a non-exhaustively explored one, aims to provide an overview on understandings of ecophysiological effects of OA and its combination with covarying drivers, mainly warming, deoxygenation and solar UV radiation. We propose a testable hypothetical model as well as future research perspectives.

This work reports on the surface-modified woven fabrics for use as UV radiation sensors. The cotton and polyamide fabrics were printed with radiochromic hydrogels using a screen-printing method. The hydrogels used as a printing paste were composed of water, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127) as a gel matrix and nitro blue tetrazolium chloride as a radiation-sensitive compound. The development of the hydrogels’ colour occurs after exposure to UV radiation and its intensity increases with increasing absorbed dose. The features of the NBT-Pluronic F-127 radiochromic hydrogels and the fabrics printed with the hydrogels were examined using UV-Vis and reflectance spectrophotometry as well as scanning electron microscopy (SEM). The effects of NBT concentration and UV radiation type (UVA, UVB, UVC) on dose responses of the hydrogels and printed fabrics were also examined. The results obtained reveal that the fabrics printed with NBT-Pluronic F-127 hydrogels can be potentially useful as UV radiation sensors.

The study of solar irradiance variability is of great importance in heliophysics, Earth’s climate, and space weather applications. These studies require careful identifying, tracking and monitoring of features in the solar photosphere, chromosphere, and corona. Do coronal bright points contribute to the solar irradiance or its variability as input to the Earth atmosphere? We studied the variability of solar irradiance for a period of 10 years (May 2010 – June 2020) using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA), and applied a linear model between the segmented features identified in the EUV images and the solar irradiance measured by LYRA. Based on EUV images from AIA, a spatial possibilistic clustering algorithm (SPoCA) is applied to identify coronal holes (CHs), and a morphological feature detection algorithm is applied to identify active regions (ARs), coronal bright points (BPs), and the quiet Sun (QS). The resulting segmentation maps were then applied on SWAP images, images of all AIA wavelengths, and parameters such as the intensity, fractional area, and contribution of ARs/CHs/BPs/QS features were computed and compared with LYRA irradiance measurements as a proxy for ultraviolet irradiation incident to the Earth atmosphere. We modeled the relation between the solar disk features (ARs, CHs, BPs, and QS) applied to EUV images against the solar irradiance as measured by LYRA and the F10.7 radio flux. A straightforward linear model was used and corresponding coefficients computed using a Bayesian method, indicating a strong influence of active regions to the EUV irradiance as measured at Earth’s atmosphere. It is concluded that the long- and short-term fluctuations of the active regions drive the EUV signal as measured at Earth’s atmosphere. A significant contribution from the bright points to the LYRA irradiance could not be found.

Long-term periodicities in the solar irradiance are often observed with periods proportional to the solar rotational period of 27 days. These periods are linked either to some internal mechanism in the Sun or said to be higher harmonics of the rotation without further discussion of their origin. In this article, the origin of the peaks in periodicities seen in the solar extreme ultraviolet (EUV) and ultraviolet (UV) irradiance around the 7, 9, and 14 days periods is discussed. Maps of the active regions and coronal holes are produced from six images per day using the Spatial Possibilistic Clustering Algorithm (SPoCA), a segmentation algorithm. Spectral irradiance at coronal, transition-region/chromospheric, and photospheric levels are extracted for each feature as well as for the full disk by applying the maps to full-disk images (at 19.3, 30.4, and 170 nm sampling in the corona/hot flare plasma, the chromosphere/transition region, and the photosphere, respectively) from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) from January 2011 to December 2018. The peaks in periodicities at 7, 9, and 14 days as well as the solar rotation around 27 days can be seen in almost all of the solar irradiance time series. The segmentation also provided time series of the active regions and coronal holes visible area (i.e. in the area observed in the AIA images, not corrected for the line-of-sight effect with respect to the solar surface), which also show similar peaks in periodicities, indicating that the periodicities are due to the change in area of the features on the solar disk rather than to their absolute irradiance. A simple model was created to reproduce the power spectral density of the area covered by active regions also showing the same peaks in periodicities. Segmentation of solar images allows us to determine that the peaks in periodicities seen in solar EUV/UV irradiance from a few days to a month are due to the change in area of the solar features, in particular, active regions, as they are the main contributors to the total full-disk irradiance variability. The higher harmonics of the solar rotation are caused by the clipping of the area signal as the regions rotate behind the solar limb.

The ocular surface is comprised of the cornea and conjunctiva, which are structures that not only protect the eye but also enable vision. The corneal epithelium is the most superficial layer of the cornea, and therefore first line of defense against external assaults. Damage to this highly specialized structure could lead to vision loss, making it an important structure to investigate and understand. Here, we conducted a search of the current literature on the mechanisms the corneal epithelium has adapted against three frequent insults: UV-radiation, pathogens, and environmental assaults. This review systematically examines the corneal epithelium's response to each assault in order to maintain its role as an invisible shield. The goal of this review is to provide insight into some of the critical functions the corneal epithelium performs that may be valuable to current regenerative studies.

Momilactones A (MA) and B (MB) are known as phytoalexins which principally play a role in the rice defense system against pathogens. This is the first study revealing that MA and MB contribute to rice tolerance to environmental stresses, including ultraviolet (UV) radiation and chilling conditions. The proofs were achieved by scrutinizing the responses of rice under stresses through the expression of relevant biosynthetic genes to momilactones (MRBG) and phenolics (PRBG) and their accumulation. Accordingly, the expression tendency of PRBG was in line with that of MRBGs, which increased under UV irradiation but decreased under chilling conditions. In UV-exposed rice, the proliferation of MA and MB strongly correlated to that of salicylic and chlorogenic acids, esculetin, rutin, and fisetin. In terms of increasing chilling duration, the biosynthetic propensity of MB was consistent with that of benzoic, cinnamic, ρ-coumaric, salicylic, and syringic acids, quercetin, and tricin while the syntheses of MA and other compounds were reduced. The concomitant biosyntheses of momilactones with these acknowledged stress-resistant phenolics imply that momilactones might play a role as signaling molecules in the response mechanism of rice to UV and chilling stresses. Further comprehensive studies should be conducted to validate this paradigmatic finding.

Skin, as the outermost organ, is exposed to a wide range of environmental risk factors including ultraviolet (UV) and all kinds of pollutants. Excessive UV exposure contributes to many disorders, such as photoaging, skin inflammation, and carcinogenesis. To determine the effects of bamboo extract (BEX) from our local plant, , on UV-irritated human skin, we conducted a variety of studies, including Western blot, apoptosis assays, reactive oxygen species (ROS) detection, and thioredoxin (TXN) and thioredoxin reductase (TXNRD) activity assays in primary skin keratinocytes. We first determined that BEX protects human skin keratinocytes against UV radiation-induced apoptosis and ROS production. UV radiation can robustly impair TXN and TXNRD activity which can, in turn, be significantly rescued by BEX treatment. Moreover, BEX regulates TXN1 levels in primary skin keratinocytes and TXN1 is proved to be required for the protective function of BEX. Last, we found that the NF-κB/p65 pathway mediates the protective function of BEX against UV. Collectively, our work delineates the beneficial role of BEX in UV-induced skin cell damage and provides a novel therapeutic reagent to prevent or alleviate the progress of photoaging and other UV-provoked skin diseases.

Drought and ultraviolet radiation (UV radiation) are the coexisting environmental factors that negatively affect plant growth and development via oxidative damage. Flavonoids are reactive, scavenging oxygen species (ROS) and UV radiation-absorbing compounds generated under stress conditions. We investigated the biosynthesis of kaempferol and quercetin in wild and flavanone 3-hydroxylase (F3H) overexpresser rice plants when drought and UV radiation stress were imposed individually and together. Phenotypic variation indicated that both kinds of stress highly reduced rice plant growth parameters in wild plants as compared to transgenic plants. When combined, the stressors adversely affected rice plant growth parameters more than when they were imposed individually. Overaccumulation of kaempferol and quercetin in transgenic plants demonstrated that both flavonoids were crucial for enhanced tolerance to such stresses. Oxidative activity assays showed that kaempferol and quercetin overaccumulation with strong non-enzymatic antioxidant activity mitigated the accumulation of ROS under drought and UV radiation stress. Lower contents of salicylic acid (SA) in transgenic plants indicated that flavonoid accumulation reduced stress, which led to the accumulation of low levels of SA. Transcriptional regulation of the dehydrin (DHN) and ultraviolet-B resistance 8 (UVR8) genes showed significant increases in transgenic plants compared to wild plants under stress. Taken together, these results confirm the usefulness of kaempferol and quercetin in enhancing tolerance to both drought and UV radiation stress.

A two-dimensional (2D) CeO2-Pd-PDA/rGO heterojunction nanocomposite has been synthesised via an environmentally friendly, energy efficient, and facile wet chemical procedure and examined for hydrogen (H2) gas sensing application for the first time. The H2 gas sensing performance of the developed conductometric sensor has been extensively investigated under different operational conditions, including working temperature up to 200 °C, UV illumination, H2 concentrations from 50–6000 ppm, and relative humidity up to 30% RH. The developed ceria-based nanocomposite sensor was functional at a relatively low working temperature (100 °C), and its sensing properties were improved under UV illumination (365 nm). The sensor’s response towards 6000 ppm H2 was drastically enhanced in a humid environment (15% RH), from 172% to 416%. Under optimised conditions, this highly sensitive and selective H2 sensor enabled the detection of H2 molecules down to 50 ppm experimentally. The sensing enhancement mechanisms of the developed sensor were explained in detail. The available 4f electrons and oxygen vacancies on the ceria surface make it a promising material for H2 sensing applications. Moreover, based on the material characterisation results, highly reactive oxidant species on the sensor surface formed the electron–hole pairs, facilitated oxygen mobility, and enhanced the H2 sensing performance.