Effects of increased solar ultraviolet radiation on materials

The influence of UV radiation on the properties of GFRP laminates in underwater conditions

Degradation of polymer composites is a significant problem in many engineering aspects. Due to the interaction of various degradation factors during the exploitation of composites, a synergistic effect of destruction is observed. The article describes the phenomena occurring in glass fiber reinforced polyester laminates under the influence of ultraviolet radiation (UV) in an aquatic environment. The laminates were exposed to UV-A, UV-B and UV-C radiation for 1000 h in free-air and underwater conditions. During the test, the materials were immersed at stable depth of 1 mm and 10 mm, respectively. The three-point bending tests performed on the samples after being exposed to UV showed an increase in the flexural strength of the composites. Simultaneously, degradation of the outer surface layer was observed. The degradation removed the thin resin film from the surface which resulted in a direct exposure of the reinforcing fibers to the environment. The transformations taking place in the deeper layers of the composite increased the mechanical strength due to the additional cross-linking reactions excited by the energy arising from the radiation. Moreover, the formation of polymer structures from free styrene remaining after the technological process and the occurrence of free radical reactions as a result of the cage effect was also observed.

Aging of plastics in aquatic environments: Pathways, environmental behavior, ecological impacts, analyses and quantifications

The ubiquity of plastics in our environment has brought about pressing concerns, with their aging processes, photo-oxidation, mechanical abrasion, and biodegradation, being at the forefront. Microplastics (MPs), whether originating from plastic degradation or direct anthropogenic sources, further complicate this landscape. This review delves into the intricate aging dynamics of plastics in aquatic environments under various influential factors. We discuss the physicochemical changes that occur in aged plastics and the release of oxidation products during their degradation. Particular attention is given to their evolving environmental interactions and the resulting ecotoxicological implications. A rigorous evaluation is also conducted for methodologies in the analysis and quantification of plastics aging, identifying their merits and limitations and suggesting potential avenues for future research. This comprehensive review is able to illuminate the complexities of plastics aging, charting a path for future research and aiding in the formulation of informed policy decisions.

Designing an Effective and Scalable UV-Protective Cooling Textile with Nanoporous Fibers

Although radiative cooling concepts guarantee reduction of air conditioning energy consumption by maximizing the scattering of solar radiation and dissipation of thermal radiation of a human body or building, large-scale implementation is challenging due to the need of radical adaptation in manufacturing processes, materials, and design. Here, we introduce an extremely thin layer of nanoporous microfibers without any additional materials or post-treatments. The optical and thermal effectiveness of porous fibers are presented to report a nondisruptive method of preventing the transmission of energy-intensive radiation such as ultraviolet radiation (UV) through textiles. Results show ∼1.4 °C cooling by adding 1 g/m2 (GSM) of porous fibers on a 160 GSM cotton t-shirt, and 91% of UV was prevented with 7.5 GSM of a porous fiber mat. This minimalistic additive approach would widen the scope of optical and radiative cooling research and accelerate both functional and sustainable materials research to be more accessible.

Efficacy of Violet-Blue (405 nm) LED Lamps for Disinfection of High-Environmental-Contact Surfaces in Healthcare Facilities: Leading to the Inactivation of Microorganisms and Reduction of MRSA Contamination

Effective disinfection procedures in healthcare facilities are essential to prevent transmission. Chemical disinfectants, hydrogen peroxide vapour (HPV) systems and ultraviolet (UV) light are commonly used methods. An emerging method, violet-blue light at 405 nm, has shown promise for surface disinfection. Its antimicrobial properties are based on producing reactive oxygen species (ROS) that lead to the inactivation of pathogens. Studies have shown significant efficacy in reducing bacterial levels on surfaces and in the air, reducing nosocomial infections. The aim of this study was to evaluate the antimicrobial effectiveness of violet-blue (405 nm) LED lamps on high-contact surfaces in a hospital infection-control laboratory. High-contact surfaces were sampled before and after 7 days of exposure to violet-blue light. In addition, the effect of violet-blue light on MRSA-contaminated surfaces was investigated. Exposure to violet-blue light significantly reduced the number of bacteria, yeasts and moulds on the sampled surfaces. The incubator handle showed a low microbial load and no growth after irradiation. The worktable and sink showed an inconsistent reduction due to shaded areas. In the second experiment, violet-blue light significantly reduced the microbial load of MRSA on surfaces, with a greater reduction on steel surfaces than on plastic surfaces. Violet-blue light at 405 nm has proven to be an effective tool for pathogen inactivation in healthcare settings Violet-blue light shows promise as an additional and integrated tool to reduce microbial contamination in hospital environments but must be used in combination with standard cleaning practices and infection control protocols. Further research is needed to optimise the violet-blue, 405 nm disinfection method.

UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in the bio-solid suspensions. The presence of carbonyl and hydroxyl groups increased with an increasing exposure time. Overall, UV radiation had the greatest impact on the MPs in the bio-solids suspension. Due to the surface-to-volume ratio of the tested samples, which influences the degradation rate, the fibers were more degraded than the other two plastic shapes. UV-A was slightly more effective at degrading the MPs than UV-C. These findings show that ultraviolet radiation in combination with an elevated temperature affects the structure of polymers in wastewater bio-solids, which can accelerate their degradation.

Spatially Controlled UV Light Generation at Depth using Upconversion Micelles

UV light can trigger a plethora of useful photochemical reactions for diverse applications, including photocatalysis, photopolymerization, and drug delivery. These applications typically require penetration of high-energy photons deep into materials, yet delivering these photons beyond the surface is extremely challenging due to absorption and scattering effects. Triplet-triplet annihilation upconversion (TTA-UC) shows great promise to circumvent this issue by generating high-energy photons from incident lower-energy photons. However, molecules that facilitate TTA-UC usually have poor water solubility, limiting their deployment in aqueous environments. To address this challenge, a nanoencapsulation method is leveraged to fabricate water-compatible UC micelles, enabling on-demand UV photon generation deep into materials. Two iridium-based complexes are presented for use as TTA-UC sensitizers with increased solubilities that facilitate the formation of highly emissive UV-upconverting micelles. Furthermore, this encapsulation method is shown to be generalizable to nineteen UV-emitting UC systems, accessing a range of upconverted UV emission profiles with wavelengths as low as 350 nm. As a proof-of-principle demonstration of precision photochemistry at depth, UV-emitting UC micelles are used to photolyze a fluorophore at a focal point nearly a centimeter beyond the surface, revealing opportunities for spatially controlled manipulation deep into UV-responsive materials.

Effects of weathering on the properties and fate of secondary microplastics from a polystyrene single-use cup

In this work, we probed the changes to some physicochemical properties of polystyrene microplastics generated from a disposable cup as a result of UV-weathering, using a range of spectroscopy, microscopy, and profilometry techniques. Thereafter, we aimed to understand how these physicochemical changes affect the microplastic transport potential and contaminant sorption ability in model freshwaters. Exposure to UV led to measured changes in microplastic hydrophobicity (20-23 % decrease), density (3% increase), carbonyl index (up to 746 % increase), and microscale roughness (24-86 % increase). The settling velocity of the microplastics increased by 53 % after weathering which suggests that UV aging can increase microplastic deposition to sediments. This impact of aging was greater than the effect of the water temperature. Weathered microplastics exhibited reduced sorption capacity (up to 52 % decrease) to a model hydrophobic contaminant (triclosan) compared to unaged ones. The adsorption of triclosan to both microplastics was slightly reversible with notable desorption hysteresis. These combined effects of weathering could potentially increase the transport potential while decreasing the contaminant transport abilities of microplastics. This work provides new insights on the sorption capacity and mobility of a secondary microplastic, advances our knowledge about their risks in aquatic environments, and the need to use environmentally relevant microplastics.

Microplastic levels on sandy beaches: Are the effects of tourism and coastal recreation really important?

This study assessed the effect of tourism and other recreational activities on microplastic (MP) levels and their characteristics in the sand and surf zone of the seawater. Six sites were chosen belonging to three sandy beaches with similar geomorphologic and morphodynamic characteristics but with different tourism activities. On average, a concentration of 1133.3 ± 811.3 items/kg dry weight (d.w.) and 12.7 ± 14.9 items/m³ were found in the sand and seawater samples, respectively. Fibers and films predominated and were less than 1 mm in length. In the sand, the films mainly matched the PE polymer spectra and the fibers matched PET polymer, cotton, and indigo blue dye; in the seawater samples, PP films and PET fibers prevailed. At the Pehuén-Co - Monte Hermoso Coastal Marine MPA where the flow of tourists is low, the MP levels were the lowest and the largest particles were found, mainly blue or black fibers, with less polymer diversity, cotton and PET being the most prevalent suggesting a recent input of textile fibers to this site. Moreover, the highest concentration of MPs was found on the southern site of a beach considered to be more pristine due to negligible human activity, including the smallest size pattern, mostly composed of white films or fibers with a greater diversity of polymers, predominantly PE > PET > PP. A great occurrence of PVC white films was also found in the surf zone at this site. Proximity to the mouth of a river, littoral drift, and other point sources were identified as the main sources, indicating that, apart from the local tourism and recreational activities, other sources might play a major role in the input of MPs to sandy beaches, such as extensive/intensive agricultural land use and irrigation areas.

Transformation of microplastics by oxidative water and wastewater treatment processes: A critical review

Microplastics (MPs) are contaminants of emerging concern that accumulate in various environments, where they pose threats to both the ecosystem and public health. Since MPs have been detected in drinking water resources and wastewater effluents, more efficient treatment is needed at wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs). This review discusses the potential of biological, photochemical, Fenton (-like) systems, ozonation, and other oxidation processes in the treatment of MPs in terms of their indicators of oxidation such as mass loss and surface oxidation. The oxidation processes were further analyzed in terms of limitations and environmental implications. Most previous studies examining MPs degradation using conventional treatments-such as UV disinfection, ozonation, and chlorination-employed significantly higher doses than the common doses applied in DWTPs and WWTPs. Owing to such dose gaps, the oxidative transformation of MPs observed in many previous studies are not likely to occur under practical conditions. Some novel oxidation processes showed promising MPs treatment efficiencies, while many of them have not yet been applied on a larger scale due to high costs and the lack of extensive basic research. Health and environmental impacts related to the discharge of oxidized MPs in effluents should be considered carefully in different aspects: the role as vectors of external pollutants, release of organic compounds (including organic byproducts from oxidation) and fragmentation into smaller particles as MPs circulate in the ecosystem as well as the possibility of bioaccumulation. Future research should also focus on ways to incorporate developed oxidation processes in DWTPs and WWTPs to mitigate MPs contamination.

Safer school with near-UV technology: novel applications for environmental hygiene

Systems capable of disinfecting air and surfaces could reduce the risk of infectious diseases transmission. Aim: to evaluate the effectiveness of near-UV LED ceiling lamps, with a wavelength of 405 nm, in improving environmental hygiene. Between November and December 2020, we conducted an experimental study having a pre-post design in a kindergarten room in Siena where 4 ceiling lamps with 405 nm LED technology were installed. Twice per day, sampling was performed before (T0) and after treatment with near-UV (T1). We used between 8 and 12 pairs of contact plates to sample at various random spots each day. Air samplings were also performed. The plates were incubated at 22 and 36 °C. Significance was set at 95% (p < 0.05). The mean level of Colony Forming Unit (CFU) at T(0) was 249 (95% CI 193.1 - 305.0) at 36 °C and 535.2 (374.3 - 696.1) at 22 °C. The reduction was significant at T(1): by 65% at 36 °C and, 72% at 22 °C. Also, for air contamination: 95.3% (98.4-92.3). A dose threshold of about 5 J/cm² was identified to have an 80% CFU abatement and remains nearly constant. The advantage of being able to use this technology in the presence of people is very important in the context of controlling environmental contamination.

Graphical abstract

Plastic-microbe interaction in the marine environment: Research methods and opportunities

Approximately 9 million metric tons of plastics enters the ocean annually, and once in the marine environment, plastic surfaces can be quickly colonised by marine microorganisms, forming a biofilm. Studies on plastic debris-biofilm associations, known as plastisphere, have increased exponentially within the last few years. In this review, we first briefly summarise methods and techniques used in exploring plastic-microbe interactions. Then we highlight research gaps and provide future research opportunities for marine plastisphere studies, especially, on plastic characterisation and standardised biodegradation tests, the fate of "environmentally friendly" plastics, and plastisphere of coastal habitats. Located in the tropics, Southeast Asian (SEA) countries are significant contributors to marine plastic debris. However, plastisphere studies in this region are lacking and therefore, we discuss how the unique environmental conditions in the SEA seas may affect plastic-microbe interaction and why there is an imperative need to conduct plastisphere studies in SEA marine environments. Finally, we also highlight the lack of understanding of the pathogenicity and ecotoxicological effects of plastisphere on marine ecosystems.

Marine-Derived Actinomycetes: Biodegradation of Plastics and Formation of PHA Bioplastics-A Circular Bioeconomy Approach

Plastics are present in the majority of daily-use products worldwide. Due to society's production and consumption patterns, plastics are accumulating in the environment, causing global pollution issues and intergenerational impacts. Our work aims to contribute to the development of solutions and sustainable methods to mitigate this pressing problem, focusing on the ability of marine-derived actinomycetes to accelerate plastics biodegradation and produce polyhydroxyalkanoates (PHAs), which are biodegradable bioplastics. The thin plastic films' biodegradation was monitored by weight loss, changes in the surface chemical structure (Infra-Red spectroscopy FTIR-ATR), and by mechanical properties (tensile strength tests). Thirty-six marine-derived actinomycete strains were screened for their plastic biodegradability potential. Among these, Streptomyces gougerotti, Micromonospora matsumotoense, and Nocardiopsis prasina revealed ability to degrade plastic films-low-density polyethylene (LDPE), polystyrene (PS) and polylactic acid (PLA) in varying conditions, namely upon the addition of yeast extract to the culture media and the use of UV pre-treated thin plastic films. Enhanced biodegradation by these bacteria was observed in both cases. S. gougerotti degraded 0.56% of LDPE films treated with UV radiation and 0.67% of PS films when inoculated with yeast extract. Additionally, N. prasina degraded 1.27% of PLA films when these were treated with UV radiation, and yeast extract was added to the culture medium. The main and most frequent differences observed in FTIR-ATR spectra during biodegradation occurred at 1740 cm^-1, indicating the formation of carbonyl groups and an increase in the intensity of the bands, which indicates oxidation. Young Modulus decreased by 30% on average. In addition, S. gougerotti and M. matsumotoense, besides biodegrading conventional plastics (LDPE and PS), were also able to use these as a carbon source to produce degradable PHA bioplastics in a circular economy concept.

Efficacy of violet-blue light to inactive microbial growth

The increase in health care-associated infections and antibiotic resistance has led to a growing interest in the search for innovative technologies to solve these problems. In recent years, the interest of the scientific community has focused on violet-blue light at 405 nm (VBL405). This study aimed to assess the VBL405 efficiency in reducing microbial growth on surfaces and air. This descriptive study run between July and October 2020. Petri dishes were contaminated with P. aeruginosa, E. coli, S. aureus, S. typhimurium, K. pneumoniae and were placed at 2 and 3 m from a LED light source having a wavelength peak at 405 nm and an irradiance respectively of 967 and 497 µW/cm². Simultaneously, the air in the room was sampled for 5 days with two air samplers (SAS) before and after the exposition to the VBL405 source. The highest microbial reduction was reached 2 m directly under the light source: S. typhimurium (2.93 log₁₀), K. pneumoniae (2.30 log₁₀), S. aureus (3.98 log₁₀), E. coli (3.83 log₁₀), P. aeruginosa (3.86 log₁₀). At a distance of 3 m from the light source, the greatest reduction was observed for S. aureus (3.49 log₁₀), and P. aeruginosa (3.80 log₁₀). An average percent microbial reduction of about 70% was found in the sampled air after 12 h of exposure to VBL405. VBL405 has proven to contrast microbial growth on the plates. Implementing this technology in the environment to provide continuous disinfection and to control microbial presence, even in the presence of people, may be an innovative solution.

Deposition of polystyrene microplastics on bare or biofilm-coated silica analysed via QCM-D

The mobility of microplastics (MPs) in aqueous media is closely related to their environmental risk. The naturally occurring silica substrate surface in the aquatic environment is easily colonized by microorganisms and forms a biofilm, which may affect the migration and distribution of MPs. Herein, a typical MP, polystyrene (PS), and Pseudomonas fluorescens (P. fluorescens) biofilms were selected to study the deposition and release of pristine or ultraviolet (UV)-aged PS MPs on silica and biofilms under different ionic strengths using a quartz crystal microbalance dissipation (QCM-D) system. Statistical analyses of the deposition experiments revealed a significant impact of P. fluorescens biofilms on deposition (p = 0.0042). The deposition rate of weathered MPs on the biofilms was 4.0 ± 0.1 to 16.3 ± 0.6 times that on silica. A release experiment revealed that the biofilm reduced the release fraction (f_r) of weathered MPs by 34.5 ± 0.3 % compared to bare silica. In addition, the UV-ageing treatment reduced the deposition mass of MPs on the surface of silica by 27.6 ± 0.21 % compared to pristine microspheres. The analysis of the deposition mechanism revealed that the promotion and inhibition of biofilm or UV-ageing treatment on the deposition of microspheres could be attributed to the non-Derjaguin-Landau-Verwey-Overbeek (DLVO) force and the decreased electrostatic repulsion or the increased hydration repulsion, respectively.

The Role of Tire Leachate in Condition-Specific Competition and the Persistence of a Resident Mosquito from a Competitively Superior Invader

(1) Background: Condition-specific competition, when the outcome of competition varies with abiotic conditions, can facilitate species coexistence in spatially or temporally variable environments. Discarded vehicle tires degrade to leach contaminants into collected rainwater that provide habitats for competing mosquito species. We tested the hypothesis that more highly degraded tires that contain greater tire leachate alters interspecific mosquito competition to produce a condition-specific advantage for the resident, Culex pipiens, by altering the outcome of competition with the competitively superior invasive Aedes albopictus. (2) Methods: In a competition trial, varying densities of newly hatched Ae. albopictus and Cx. pipiens larvae were added to tires that had been exposed to three different ultraviolet (UV)-B conditions that mimicked full-sun, shade, or no UV-B conditions in the field. We also measured Cx. pipiens and Ae. albopictus oviposition preference among four treatments with varying tire leachate (high and low) and resources (high and low) amounts to determine if adult gravid females avoided habitats with higher tire leachate. (3) Results: We found stronger competitive effects of Cx. pipiens on the population performance and survival of Ae. albopictus in tires exposed to shade and full-sun conditions that had higher concentrations of contaminants. Further, zinc concentration was higher in emergent adults of Ae. albopictus than Cx. pipiens. Oviposition by these species was similar between tire leachate treatments but not by resource amount. (4) Conclusions: These results suggest that degraded tires with higher tire leachate may promote condition-specific competition by reducing the competitive advantage of invasive Ae. albopictus over resident Cx. pipiens and, combined with Cx. pipiens' preferential oviposition in higher resource sites, contribute to the persistence of the resident species.

Durable radiative cooling against environmental aging

To fight against global warming, subambient daytime radiative cooling technology provides a promising path to meet sustainable development goals. To achieve subambient daytime radiative cooling, the reflection of most sunlight is the essential prerequisite. However, the desired high solar reflectance is easily dampened by environmental aging, mainly natural soiling and ultraviolet irradiation from sunlight causing yellowish color for most polymers, making the cooling ineffective. We demonstrate a simple strategy to use titanium dioxide nanoparticles, with ultraviolet resistance, forming hierarchical porous morphology via evaporation-driven assembly, which guarantees a balanced anti-soiling and high solar reflectance, rendering anti-aging cooling paint based coatings. We challenge the cooling coatings in an accelerated weathering test against simulated 3 years of natural soiling and simulated 1 year of natural sunshine, and find that the solar reflectance only declined by 0.4% and 0.5% compared with the un-aged ones. We further show over 6 months of aging under real-world conditions with barely no degradation to the cooling performance. Our anti-aging cooling paint is scalable and can be spray coated on desired outdoor architecture and container, presenting durable radiative cooling, promising for real-world applications.

Environmental contamination by microplastics originating from textiles: Emission, transport, fate and toxicity

Microplastic (MP) pollution has become a global concern in terms of its environmental abundance and potential detrimental effects. Fibrous microplastics (FMPs) released from synthetic textiles are believed to contribute significantly to environmental MP pollution. This review provides an overview of current knowledge relating to the environmental impact of FMPs through a summary and discussion of (1) the concentrations in different environmental compartments including water, soil and air, (2) emission from wastewater treatment plants: via effluent discharges to waters and via sludge to land, (3) environmental transport and fate, and (4) toxicity and associated effects. How the properties of FMPs influence these aspects is discussed and their behaviour is compared to MPs of other shapes. We have summarised the Environmental Concentrations and derived Predicted No-Effect Concentrations for a preliminary risk assessment of FMPs by extrapolating the risk quotient for each respective environmental compartment. The uncertainties surrounding current assessment methods are discussed. In particular we address the need to improve determination of exposure levels and to better characterise the effects of FMPs. We conclude by presenting topics for future studies to address, which will improve our still limited understanding of the interactions between FMPs and the environment.

Weathering pathways and protocols for environmentally relevant microplastics and nanoplastics: What are we missing?

To date, most studies of microplastics have been carried out with pristine particles. However, most plastics in the environment will be aged to some extent; hence, understanding the effects of weathering and accurately mimicking weathering processes are crucial. By using microplastics that lack environmental relevance, we are unable to fully assess the risks associated with microplastic pollution in the environment. Emerging studies advocate for harmonization of experimental methods, however, the subject of reliable weathering protocols for realistic assessment has not been addressed. In this work, we critically analysed the current knowledge regarding protocols used for generating environmentally relevant microplastics and leachates for effects studies. We present the expected and overlooked weathering pathways that plastics will undergo throughout their lifecycle. International standard weathering protocols developed for polymers were critically analysed for their appropriateness for use in microplastics research. We show that most studies using weathered microplastics involve sorption experiments followed by toxicity assays. The most frequently reported weathered plastic types in the literature are polystyrene>polyethylene>polypropylene>polyvinyl chloride, which does not reflect the global plastic production and plastic types detected globally. Only ~10% of published effect studies have used aged microplastics and of these, only 12 use aged nanoplastics. This highlights the need to embrace the use of environmentally relevant microplastics and to pay critical attention to the appropriateness of the weathering methods adopted moving forward. We advocate for quality reporting of weathering protocols and characterisation for harmonization and reproducibility across different research efforts.

ADH2/GSNOR1 is a key player in limiting genotoxic damage mediated by formaldehyde and UV-B in Arabidopsis

Maintenance of genome stability is an essential requirement for all living organisms. Formaldehyde and UV-B irradiation cause DNA damage and affect genome stability, growth and development, but the interplay between these two genotoxic factors is poorly understood in plants. We show that Arabidopsis adh2/gsnor1 mutant, which lacks alcohol dehydrogenase 2/S-nitrosoglutathione reductase 1 (ADH2/GSNOR1), are hypersensitive to low fluence UV-B irradiation or UV-B irradiation-mimetic chemicals. Although the ADH2/GSNOR1 enzyme can act on different substrates, notably on S-hydroxymethylglutathione (HMG) and S-nitrosoglutathione (GSNO), our study provides several lines of evidence that the sensitivity of gsnor1 to UV-B is caused mainly by UV-B-induced formaldehyde accumulation rather than other factors such as alteration of the GSNO concentration. Our results demonstrate an interplay between formaldehyde and UV-B that exacerbates genome instability, leading to severe DNA damage and impaired growth and development in Arabidopsis, and show that ADH2/GSNOR1 is a key player in combating these effects.

Accelerated Aging Effect on Mechanical Properties of Common 3D-Printing Polymers

In outdoor environments, the action of the Sun through its ultraviolet radiation has a degrading effect on most materials, with polymers being among those affected. In the past few years, 3D printing has seen an increased usage in fabricating parts for functional applications, including parts destined for outdoor use. This paper analyzes the effect of accelerated aging through prolonged exposure to UV-B on the mechanical properties of parts 3D printed from the commonly used polymers polylactic acid (PLA) and polyethylene terephthalate–glycol (PETG). Samples 3D printed from these materials went through a dry 24 h UV-B exposure aging treatment and were then tested against a control group for changes in mechanical properties. Both the tensile and compressive strengths were determined, as well as changes in material creep characteristics. After irradiation, PLA and PETG parts saw significant decreases in both tensile strength (PLA: −5.3%; PETG: −36%) and compression strength (PLA: −6.3%; PETG: −38.3%). Part stiffness did not change significantly following the UV-B exposure and creep behavior was closely connected to the decrease in mechanical properties. A scanning electron microscopy (SEM) fractographic analysis was carried out to better understand the failure mechanism and material structural changes in tensile loaded, accelerated aged parts.

The Impact of Ultraviolet-B Radiation on the Sugar Contents and Protective Enzymes in Acyrthosiphon pisum

Natural and anthropogenic changes have been altering many environmental factors. These include the amount of solar radiation reaching the Earth's surface. However, the effects of solar radiation on insect physiology have received little attention. As a pest for agriculture and horticulture, aphids are one of the most difficult pest groups to control due to their small size, high fecundity, and non-sexual reproduction. Study of the effects of UV-B radiation on aphid physiology may provide alternative control strategies in pest management. In this study, we examined the effects of UV-B radiation on protein and sugar contents, as well as the activities of protective enzymes, of the red and green morphs of the pea aphid over eight generations. The results indicated a significant interaction between UV-B radiation and aphid generations. Exposure of the pea aphids to UV-B radiation caused a significant decrease in the protein content and a significant increase in the glycogen and trehalose contents at each generation as measured in whole aphid bioassays. The enzyme activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) of the pea aphids changed significantly at each generation with UV-B treatments. The SOD activity increased over eight generations to the highest level at G7 generation. However, the enzyme activity of CAT first increased and then decreased with UV-B treatments, and POD mostly gradually decreased over the eight generations. Therefore, UV-B radiation is an environmental factor that could result in physiological changes of the pea aphid. Moreover, our study discovered that red and green aphids did not display a significant consistent difference in the response to the UV-B treatments. These results may prove useful in future studies especially for assessing their significance in the adaptation and management against UV-B radiation.

Aging assessment of microplastics (LDPE, PET and uPVC) under urban environment stressors

The changes in the chemical structure, surface morphology and crystallinity are reported for three different polymers (LDPE, PET and uPVC) in microplastic form, after being artificially exposed to different aging agents that can affect microplastics in urban environments: ozone, UV-C, and solar radiation. In parallel to the laboratory experiments, the microplastics were exposed to real weathering conditions for three-months in a building rooftop located in the city of Porto (Portugal). By analysing the (virgin and aged) microplastic samples periodically through ATR-FTIR spectroscopy and estimating the Carbonyl Index, it was possible to sketch the aging degree evolution through time and identify the most aggressive agents for each polymer regarding the changes in their chemical structure. SEM and XRD measurements allowed to complement the ATR-FTIR results, giving a more complete picture of the effects of each treatment on each polymer and suggesting that ATR-FTIR measurements are not sufficient to correctly evaluate the aging degree of microplastics. The changes observed in the microplastic particles studied support the theory that microplastics in the environment undergo aging and change their characteristics through time, potentially affecting their behavior and intensifying their impacts.

The life of a plastic butter tub in riverine environments

Plastic pollution in the world's ocean is one of the major environmental challenges that affects the society today, due to their persistence at sea, adverse consequences to marine life and being potentially harmful to human health. Rivers are now widely recognized as being the major input source of land-based plastic waste into the seas. Despite their key role in plastic transportation, riverine plastic pollution research is still in its infancy and plastic sources, hot-spots and degradation processes in riverine systems are to date poorly understood. In this contribution, we introduce a novel concept of following the aging of polypropylene based post-consumer goods placed in known trapping and mobility zones of macroplastics on a fluvial point bar, which was determined through repeated field surveys of macroplastic densities on this bar. As a proof-of-concept, we followed the degradation of 5 identical plastic butter tubs in 5 different locations on a riverbank and significant differences in the aging of the tubs were observed. The degree of aging of the tubs can to some extent be correlated to their proximity to the main river channel, exposure to natural conditions, such as solar radiation, and its storage time on land.

Pulsed blue light inactivates two strains of human coronavirus

Emerging evidence suggests that blue light has the potential to inactivate viruses. Therefore, we investigated the effect of 405 nm, 410 nm, 425 nm and 450 nm pulsed blue light (PBL) on human alpha coronavirus HCoV-229 E and human beta coronavirus HCoV-OC43, using Qubit fluorometry and RT-LAMP to quantitate the amount of nucleic acid in irradiated and control samples. Like SARS-CoV-2, HCoV-229E and HCoV-OC43 are single stranded RNA viruses transmitted by air and direct contact; they have similar genomic sizes as SARS-CoV-2, and are used as surrogates for SARS-CoV-2. Irradiation was carried out either at 32.4 J cm^-2 using 3 mW cm^-2 irradiance or at 130 J cm^-2 using 12 mW cm^-2 irradiance. Results: (1) At each wavelength tested, PBL was antiviral against both coronaviruses. (2) 405 nm light gave the best result, yielding 52.3% (2.37 log₁₀) inactivation against HCoV-OC43 (p < .0001), and a significant 1.46 log ₁₀ (44%) inactivation of HCoV-229E (p < .01). HCoV-OC43, which like SARS-CoV-2 is a beta coronavirus, was more susceptible to PBL irradiation than alpha coronavirus HCoV-229E. The latter finding suggests that PBL is potentially antiviral against multiple coronavirus strains, and that, while its potency may vary from one virus to another, it seems more antiviral against beta coronaviruses, such as HCoV-OC43. (3) Further, the antiviral effect of PBL was better at a higher irradiance than a lower irradiance, and this indicates that with further refinement, a protocol capable of yielding 100% inactivation of viruses is attainable.

Enhanced in vitro toxicity of plastic leachates after UV irradiation

Plastics can release numerous chemicals and thereby, contribute to the chemical pollution in aquatic systems. To which extent environmental degradation processes influence the release of plastic chemicals, is currently unknown and subject of research. We therefore evaluated aqueous leachates of 12 differently formulated plastics (e.g., pre-production, post-industrial and recycled pellets as well as final products) using in vitro bioassays and chemical analysis via LC-HRMS nontarget approach. We weathered these plastics by UV irradiation (UV-C and UV-A/B) under laboratory conditions in dryness and a subsequent leaching period in ultrapure water ('atmospheric' weathering) or directly in water ('aquatic' weathering, UV-A/B_aq). A dark control (DC) without UV light served as a reference treatment. Some plastics triggered several toxicological endpoints (low-density polyethylene recyclate (LDPE-R), starch blend (SB), bio-based polybutylene succinate (Bio-PBS) and polyvinyl chloride (PVC)), whereas others caused little to no effects (polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP) and LDPE). UV irradiation enhanced the plastics' toxicity, even for samples initially evaluated as toxicologically inconspicuous. The plastic samples caused oxidative stress (85%), baseline toxicity (42%), antiestrogenicity (40%) and antiandrogenicity (27%). Positive findings were measured after UV-C (63%) and UV-A/B_aq (50%) treatments, followed by UV-A/B (48%) and DC (33%). Overall, we detected between 42 (DC) and 2896 (UV-A/B_aq) chemical compounds. Our study demonstrates that differently formulated plastics leach toxic chemicals. UV exacerbates the plastics' toxicity by either generating active compounds and/or by facilitating their release. UV light even leads to the release of bioactive compounds from plastics of low chemical complexity. To prevent the exposure to plastic-associated chemicals, the application of chemicals could be reduced to a minimum, while on a regulatory level the evaluation of plastic eluates could be another focal point next to singular compounds.

First-principles based theoretical investigation of impact of polyolefin structure on photooxidation behavior

Despite their mass production and large applications, polyolefins' stability and durability toward the air, moisture, and weather resistance is a challenge for the ecosystem. After long-term exposure to ultraviolet (UV) radiation or high-temperature or erosion, polyolefins undergo degradation generating microplastics (MPs). The MPs generated after the degradation of these polyolefins are hazardous for the ecosystem. In the present work, we have carried out density functional theory (DFT) studies to investigate the photodegradation of six different polyolefins ranging from polyethylene to polydecene, differing in side-chain. Herein, we have investigated photooxidized derivatives of different polyolefins and analyzed their relative stability, conformations, UV-visible spectral behavior, and carbonyl index. The photooxidized derivatives of various polyolefins formed during degradation are examined. The time-dependent density functional theory analysis confirms that the carbonyl groups of photooxidized products show absorption peak in Infrared (IR) and visible region, acting as light-absorbing species. The relative stabilities of hydroperoxide formed during photo/thermal oxidation of different polyolefins have been evaluated to explain the degradation behavior. The oligomerization and stabilization energies of their corresponding hydroperoxide's were computed and analyzed to explain the degradation behavior of the polyolefins. The computed results suggest that polyolefins in their pristine state are stable toward photooxidation, but chemical impurities like carbonyl, unsaturated carbonyl, carboxylic acid, and hydroperoxide derivatives make them prone to undergo degradation, a fundamental process leading to generation of MPs. The comparative results confirmed that the side-chain length affects the stability and degradation of different polyolefins toward photooxidation.

High frequency of micro- and meso-plastics ingestion in a sample of neonate sea turtles from a major rookery

We studied marine litter ingestion in 380 neonate sea turtles that washed ashore dead onto Florida's central Atlantic coast (USA) following onshore winds. Our sample of "washbacks" included 284 loggerheads (Caretta caretta), 95 green turtles (Chelonia mydas), and one hawksbill (Eretmochelys imbricata). Of these, 78.7% had ingested plastics and 45.3% had ingested tar. There was a significant relationship between turtles' carapace length and total mass of ingested plastic. Ingested plastics included microplastics (<5 mm) and larger sizes up to 25% of carapace length. Washbacks' body condition indices were significantly poorer than condition indices of wild turtles captured at sea. Washbacks showed a negative association between plastic load and body condition index, evidence that high plastic loads resulted in diminished nutrition, with possible effects on somatic growth, stage duration, and survivorship. Evidence points to plastics ingestion being an important source of population-level effects in neonate sea turtles.

Fluorescent polymers via post-polymerization modification of Biginelli-type polymers for cellular protection against UV damage

Biocompatible fluorescent polymers with UV-protective capability have been developed by the combination of the Biginelli reaction and the postpolymerization modification method.

Preparation of thermostable and compatible citrate-based polyesters for enhancing the ultraviolet shielding performance of thermoplastic resin

A new class of citrate-based polyesters with excellent ultraviolet absorption characteristic was synthesized as polymer additive to enhance ultraviolet shielding performance of PETG.

Laboratory simulation of microplastics weathering and its adsorption behaviors in an aqueous environment: A systematic review

Microplastics (MPs) pollution has become a global environmental concern. MPs alone and in combination with pollutants can potentially cause significant harm to organisms and human beings. Weathering of MPs under various environmental stresses increases the uncertainty of their environmental fates. Compared with field surveys, laboratory simulation experiments are appropriate to simplify the research procedures and investigate the mechanisms. In this review, the effects of abrasion, solar radiation, chemical and thermal oxidation, microbial adhesion and colonization, and other environmental factors on the MPs and the relative laboratory simulation methods were summarized and discussed. Photo-oxidation and abrasion are the most appliable methods due to easy operation and adjustable weathering degree. Furthermore, the structural and components changes in weathering process and the applied characterization methods were generalized. In addition, one of important environmental behaviors, adsorption of the weathered MPs towards two typical pollutants was analyzed. Finally, three priorities for research were proposed. This paper conducts systematic summarized of the MPs weathering process and provides a reference for future studies to accurately determine the environmental risks of weathering MPs.

Environmental Profile on Building Material Passports for Hot Climates

Vernacular building materials and models represent the construction methods and building materials used in a healthy manner. Local building materials such as gravel, sand, stone, and clay are used in their natural state or with minor processing and cleaning to mainly satisfy local household needs (production of concrete, mortar, ballast, silicate, and clay bricks and other products). In hot climates, the concept of natural building materials was used in a form that can currently be applied in different kinds of buildings. This concept depends on the proper consideration of the climate characteristics of the construction area. A material passport is a qualitative and quantitative documentation of the material composition of a building, displaying materials embedded in buildings as well as showing their recycling potential and environmental impact. This study will consider two usages of building materials. The first is the traditional use of building materials and their importance in the application of vernacular building strategies as an essential global bioclimatic method in sustainable architecture. The second is the affordable use of new building materials for their availability and utilization by a large part of society in a way to add more detail to research. The article aims to create an objective reading and analysis regarding specific building materials in order to generate a competent solution of materials that is suitable for building requirements in hot climates. This study evaluates the most suitable Building Material Passports needed in hot climates, where the environmental profile must be analyzed to confirm the use of natural materials.

Factors influencing the antimicrobial efficacy of Dielectric Barrier Discharge (DBD) Atmospheric Cold Plasma (ACP) in food processing applications

Atmospheric cold plasma (ACP) is an emerging technology in the food industry with a huge antimicrobial potential to improve safety and extend the shelf life of food products. Dielectric barrier discharge (DBD) is a popular approach for generating ACP. Thanks to the numerous advantages of DBD ACP, it is proving to be successful in a number of applications, including microbial decontamination of foods. The antimicrobial efficacy of DBD ACP is influenced by multiple factors. This review presents an overview of ACP sources, with an emphasis on DBD, and an analysis of their antimicrobial efficacy in foods in open atmosphere and in-package modes. Specifically, the influence of process, product, and microbiological factors influencing the antimicrobial efficacy of DBD ACP are critically reviewed. DBD ACP is a promising technology that can improve food safety with minimal impact on food quality under optimal conditions. Once the issues pertinent to scale-up of plasma sources are appropriately addressed, the DBD ACP technology will find wider adaptation in food industry.

Spectrum of virucidal activity from ultraviolet to infrared radiation

The COVID-19 pandemic has sparked a demand for safe and highly effective decontamination techniques for both personal protective equipment (PPE) and hospital and operating rooms. The gradual lifting of lockdown restrictions warrants the expansion of these measures into the outpatient arena. Ultraviolet C (UVC) radiation has well-known germicidal properties and is among the most frequently reported decontamination techniques used today. However, there is evidence that wavelengths beyond the traditional 254 nm UVC - namely far UVC (222 nm), ultraviolet B, ultraviolet A, visible light, and infrared radiation - have germicidal properties as well. This review will cover current literature regarding the germicidal effects of wavelengths ranging from UVC through the infrared waveband with an emphasis on their activity against viruses, and their potential applicability in the healthcare setting for general decontamination during an infectious outbreak.

Strong Opto-Structural Coupling in Low Dimensional GeSe3 Films

Chalcogenide glasses as nanoscale thin films have become leading candidates for several optical and photonic technologies, ranging from reflective displays and filters to photonic memories. Current material systems, however, show strong optical absorption which limits their performance efficiencies and complicates device level integration. Herein, we report sputter deposited thin films of GeSe₃, which are low loss and in which the flexible nature of the atomic structure results in thermally activated tunability in the refractive index as well as in the film's physical volume. Such changes, which occur beyond a threshold temperature are observed to be accumulative and directed toward a more equilibrium amorphous state of the film, instead of crystallization. Our results provide insight into a new type of configurability that is based on strong coupling in the material's opto-structural properties. The low optical losses in this material system combined with the tunability in the optical properties in the visible and near-infrared have direct application in higher performing optical coatings and in corrective optics.

Fouling Microbial Communities on Plastics Compared with Wood and Steel: Are They Substrate- or Location-Specific?

Although marine biofouling has been widely studied on different substrates, information on biofouling on plastics in the Arabian Gulf is limited. Substrate- and location-specific effects were investigated by comparing the microbial communities developed on polyethylene terephthalate (PET) and polyethylene (PE) with those on steel and wood, at two locations in the Sea of Oman. Total biomass was lower on PET and PE than on steel and wood. PET had the highest bacterial abundance at both locations, whereas chlorophyll a concentrations did not vary between substrates. MiSeq 16S ribosomal RNA sequencing revealed comparable operational taxonomic unit (OTU) richness on all substrates at one location but lower numbers on PET and PE at the other location. Non-metric multidimensional scaling (NMDS) showed distinct clusters of the bacterial communities based on substrate (analysis of similarity (ANOSIM), R = 0.45-0.97, p < 0.03) and location (ANOSIM, R = 0.56, p < 0.0001). The bacterial genera Microcystis and Hydrogenophaga and the diatoms Licmophora and Mastogloia were specifically detected on plastics. Desulfovibrio and Pseudomonas spp. exhibited their highest abundance on steel and Corynebacterium spp. on wood. Scanning electron microscopy (SEM) revealed fissure formation on PET and PE, indicating physical degradation. The presence of free radicals on PET and carbonyl bonds (C=O) on PE, as revealed by Fourier transform infrared (FTIR) spectroscopy, indicated abiotic degradation while hydroxyl groups and spectral peaks for proteins and polysaccharides on PE indicated biotic degradation. We conclude that fouling microbial communities are not only substrate-specific but also location-specific and microbes developing on plastics could potentially contribute to their degradation in the marine environment.

Microplastics in the Northwestern Pacific: Abundance, distribution, and characteristics

Prevalence of microplastics (MPs) throughout the world's oceans has raised growing concerns due to its detrimental effects on the environment and living organisms. Most recent studies of MPs, however, have focused on the estuaries and coastal regions. There is a lack of study of MPs pollution in the open ocean. In the present study, we conducted field observations to investigate the abundance, spatial distribution, and characteristics (composite, size, color, shape and surface morphology) of MPs at the surface of the Northwestern Pacific Ocean. Samples of MPs were collected at 18 field stations in the Northwestern Pacific Ocean using a surface manta trawl with a mesh size of ~330 μm and width of 1 m from August 25 to September 26, 2017. The MPs were characterized using light microscopy, Micro-Raman spectroscopy, and scanning electron microscopy (SEM). Our field survey results indicate the ubiquity of MPs at all stations with an abundance from 6.4 × 10² items km^-2 to 4.2 × 10⁴ items km^-2 and an average abundance of 1.0 × 10⁴ items km^-2. The Micro-Raman spectroscopic analysis of the MPs samples collected during our field survey indicates that the dominant MPs is polyethylene (57.8%), followed by polypropylene (36.0%) and nylon (3.4%). The individual chemical compositions of MPs from the stations within the latitude range 123-146°E are comparable with each other, with PE being the dominating composition. Similar chemical fingerprints were observed at these field stations, suggesting that the MPs originated from similar sources. In contrast, the major MPs at the field stations adjacent to Japan is polypropylene, which may originate from the nearby land along the coast of Japan. Physical oceanography parameters were also collected at these stations. The spatial distribution of MPs is largely attributed to the combined effects of flow pattern, adjacent ocean circulation eddies, the Kuroshio and Kuroshio Extension system.

Effects of ultraviolet radiation on metabolic rate and fitness of Aedes albopictus and Culex pipiens mosquitoes

Natural and anthropogenic changes (e.g., land use change, pollution) will alter many environmental factors in the coming years, including the amount of solar radiation reaching the earth's surface. Alterations in solar radiation exposure is likely to impact the ecologies of many living organisms, including invertebrates that inhabit aquatic habitats. In this study, we assessed the effect of UV-B radiation on the metabolic rates and fitness (survival, development time, body size) of Aedes albopictus and Culex pipiens mosquitoes and the activity of their microbial food resources in experimental aquatic microcosms. We exposed single-species cohorts of newly hatched Ae. albopictus and Cx. pipiens larvae and a control treatment with no larvae to three UV-B conditions that mimicked those in full-sun and shade in the field and to a control condition with no UV-B radiation. Our results indicated that UV-B radiation affected the metabolic rates of both Ae. albopictus and Cx. pipiens larvae, with significantly higher rates found in full-sun compared to shade and no-UV conditions, 8 and 15 days after exposure began. Ae. albopictus and Cx. pipiens survival was also affected by UV-B radiation condition, with significantly lower survival in full-sun compared to shade and no UV-B conditions. Microbial metabolic rates were consistently significantly lower in full-sun compared to shade and no-UV conditions, especially at 8 days of exposure. These results show that UV-B radiation at levels found in open spaces showed strong and important impacts on the metabolic rates and survival of Ae. albopictus and Cx. pipiens larvae. Decreased survival of Ae. albopictus and Cx. pipiens with higher UV-B radiation levels may be caused by both direct exposure to radiation as well as the indirect effects of reduced microbial food, resulting in greater metabolic demands and stress. Negative impacts of UV-B radiation on the survival of Ae. albopictus and Cx. pipiens are likely to have important implications for the distribution and abundance of these mosquitoes, and the transmission of pathogens that these two broadly distributed mosquitoes vector.

Comparisons of analytical chemistry and biological activities of extracts from North Pacific gyre plastics with UV-treated and untreated plastics using in vitro and in vivo models

Plastic debris is an emerging worldwide threat to marine biota. Marine species may face unique challenges in low-flow estuarine systems with a high abundance of "macro-sized" (>4.75 mm) plastic due to the leaching of constituents and adsorbed contaminants. To simulate this leaching process, plastic samples recovered from the North Pacific Gyre along with corresponding UV-irradiated virgin plastic and non-irradiated virgin plastic counterparts were incubated in saltwater for 30 days at ambient temperatures ranging from 17 to 25 °C. Following solid-phase extraction, water samples were fractionated with sequential methanol elution from 10 to 100% and evaluated using in vitro assays assessing estrogen receptor (ER) and aryl hydrocarbon receptor (AhR) activities. In vivo responses (vitellogenin [vtg] and cytochrome p450 1A [cyp1a] mRNA) were measured following 5-day exposures in Japanese medaka (Oryzias latipes) larvae (3 days post hatch). Estrogenic plasticizers, co-planar PCBs and PAHs were quantified in the extracts using targeted GC-MS/MS and UPLC-MS/MS. In vitro estrogenicity showed highest activity in the 70% methanol fraction for all plastic leachate exposures. Whole extract in vitro estradiol equivalent (EEQ) values were 4.34 ± 2.65, 8.79 ± 2.09 and 13.78 ± 3.64 ng/L, for virgin plastic, UV-irradiated virgin plastic and North Pacific Gyre-recovered plastic, respectively (mean ± SD). Significant vtg induction was observed in medaka larvae exposed to leachate extracts from North Pacific Gyre-recovered plastic and UV-irradiated virgin plastic (9.9-fold, p = 0.039 and 10.1-fold, p = 0.042, respectively). Chemically-determined EEQ values were also localized in the 70% methanol fraction. Whole leachate extract chemical EEQ values were 0.33 ± 0.07, 1.64 ± 0.62 and 11.4 ± 2.13 ng/L, for virgin plastic, UV-irradiated virgin plastic and North Pacific Gyre-recovered plastic, respectively. In-vitro AhR activity was highest in the 70% methanol elution with greater activity in North Pacific Gyre-recovered plastic than in virgin plastic and UV-irradiated virgin plastic (toxic equivalency [TEQ] = 1.06 ± 0.54, 0.38 ± 0.07 and 0.71 ± 0.47 ng/L, respectively). CYP1A mRNA was significantly induced in larval medaka exposed to North Pacific Gyre-recovered plastic leachates (17.8-fold, p = 0.02) while exposure to virgin plastic and UV-irradiated virgin plastic leachates caused no significant change. Chemically-determined TEQ analysis for AhR indicated highest activity in the 90% methanol fraction for all leachates, with whole extract in vitro TEQs being 1.47 ± 0.87, 0.03 ± 0.05 and 0.42 ± 0.38 ng/L for North Pacific Gyre-recovered plastic, virgin plastic and UV-irradiated virgin plastic, respectively. These results indicate that weathering and UV radiation release estrogenic plasticizers and demonstrate the ability for plastics to transport adsorbed persistent organic pollutants at eco-toxicologically relevant concentrations.