Artificial UV Research Articles

Digital color analysis and machine learning for ballpoint pen ink clustering and aging investigation

Fraudulent activities often involve document manipulation, which poses a significant challenge to forensic science. To address this issue, a novel method was developed that combines intended artificial UV pre-degradation, digital color analysis (DCA) of stroke images, and various machine learning (ML) models. This method can cluster blue ballpoint pen inks and predict their photodegradation time. The results of the study indicate that the k-shape clustering method is highly effective in differentiating between inks based on their degradation curve patterns and HSV or RBS color features, aligning well with results from chromatography analyses. Furthermore, the random forest regression model demonstrated superior performance in predicting age, exhibiting the highest coefficients of determination. The DCA-ML method is a straightforward, cost-effective, and highly accurate solution for clustering blue pen inks. Using photodegradation curves to predict document age could eliminate the need for conventional physicochemical analysis techniques.

Assessing the durability of diverse leather tanning techniques for the manufacturing of leather goods through artificial aging processes

In the context of the growing demand for sustainable consumption, especially in the fashion industry, leather remains an intriguing material. Its durability and quality not only ensure the longevity of products but also support the rise of practices like second-hand use and upcycling. This study evaluates the longevity of tanning alternatives - triazine-based and a combination of synthetic and vegetable tannins - compared to the widely used chrome tanning. Artificial aging processes, incorporating heat, humidity, UV exposure, and microbial conditions, were applied to leathers tanned with the three methods. Physico-mechanical measurements, commonly specified in industrial standards, were conducted alongside chemical analyses to evaluate potential degradations associated with chrome tanning as the reference. The aging processes impacted leather performances, but finished leathers remained suitable for applications. Indeed, results on finished leathers indicated minimal degradation after aging, emphasizing the importance of the protective layer for longevity. Considerations include adapting finishing to surface structures and addressing potential stiffness in triazine-tanned leather, necessitating further exploration.

The National Cancer Aid monitoring (NCAM-online) of ultraviolet radiation risk and protection behavior: a population-based observational trend study with four annual online survey waves

BackgroundUltraviolet (UV) radiation is the most important risk factor for skin cancer development. Sunlight is the main source of UV radiation in the general population. In addition, tanning beds are a source of artificial UV radiation. Since the incidence of skin cancer is increasing worldwide, it is necessary to monitor UV-related risk behaviors such as intentional indoor and outdoor tanning, as well as sun protection behavior in the general population and specific subgroups and settings. This is the aim of the National Cancer Aid Monitoring online (NCAM-online), a continuation and further development of the NCAM.MethodsThe NCAM-online is a longitudinal trend study consisting of four annual survey waves. Each year, 4,000 individuals aged 16–65 years living in Germany will be surveyed using online questionnaires. Each year, intentional indoor and outdoor tanning will be assessed. In addition, varying specific topics regarding skin cancer prevention, such as the utilization of skin cancer screening, will be addressed in the questionnaires.DiscussionThe findings of the NCAM-online will provide an important basis for the German Cancer Aid and Working Group on Dermatologic Prevention (Arbeitsgemeinschaft Dermatologische Prävention, ADP) to develop targeted prevention campaigns and projects aimed at preventing skin cancer. The explorative nature of the NCAM-online allows for the identification of new potential starting points for prevention and education. In addition, the longitudinal design allows for a description of the trend in the prevalence of intentional tanning. For tanning bed use, representative trend data from 2012 are available for Germany, to which NCAM-online will add annual data until 2027.

Method development and process validation in dermatology: assessing methods of UV exposure for inducing skin tanning and efficacy evaluation of anti-tanning agents

Background: Understanding the differential impacts of natural versus artificial UV exposure and validating a method to evaluate tanning prevention products are crucial for advancements in dermatological research and skincare. This study aimed to develop and validate a process for inducing skin tanning using natural sunlight and artificial UV-lamps, determining the optimal UV dosages to induce controlled tanning and erythema. Methods: Six adults aged 18 to 55 were exposed to natural sunlight and a 365nm UV-lamp, with incremental exposure times and doses. Sunlight exposure was at 7600 μW/cm2 for 20, 35, and 50 minutes, while the UV-lamp provided 78, 97.5, and 117 mJ/cm² doses. Skin tan and erythema were measured using Mexameter® MX-18-probe on days 1, 3, and 7. Test products A and B were applied to evaluate their protective efficacy, with untreated sites as controls. Safety assessments included dermatological evaluations for adverse effects. Results: Sunlight exposure led to a mean erythema index (EI) increase of 40.22, 42.55-, and 47.12-units post-exposure, and mean melanin index (MI) increase of 37.78, 46.22, and 59.20 units by day 3. UV-lamp exposure resulted in less consistent increases, with maximum EI rise of 12.09 units and MI rise of 7.79 units. Test products significantly prevented tanning and erythema compared to untreated sites, with no adverse effects observed. Conclusions: Direct sunlight exposure was more effective than artificial UV-light in reliably inducing tanning and erythema, establishing it as a method for such studies. The UV-lamp doses were insufficient for consistent results. The study validated a method for evaluating anti-tanning products, confirming their efficacy and safety. These findings support further research and optimization in UV exposure techniques, standardizing a method to induce tanning using direct sunlight exposure.

Graphitic carbon nitride supported silver nanoparticles (AgNPs/g-C3N4): synthesis and photocatalytic behavior in the degradation of 2,4-dichlorophenoxyacetic acid.

Graphitic carbon nitride supported silver nanoparticles (AgNPs/g-C3N4) with 1%, 3%, and 5% AgNPs were successfully synthesized by an "ex situ" method with ultrasound of a mixture of AgNP solution and g-C3N4. The AgNP solution was prepared by chemical reduction with trisodium citrate, and g-C3N4 was synthesized from the urea precursor. The supported nanoparticles were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption (BET), Fourier transformation infrared (FTIR) and Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), electron paramagnetic resonance (EPR) and electrochemical impedance spectroscopy (EIS) Nyquist plots. The visible light-driven photocurrent measurement was performed by three on-off cycles of intermittent irradiation. The analyses show that AgNPs were evenly dispersed on g-C3N4, and have sizes ranging from 40 to 50 nm. The optical properties of the AgNPs/g-C3N4 material were significantly enhanced due to the plasmonic effect of AgNPs. The photocatalytic activity of catalysts was evaluated by 2,4-D degradation under visible light irradiation (λ > 420 nm). In the reaction conditions: pH 2.2; C o (2,4-D) 40 ppm; a m/v ratio of 0.5 g L-1, AgNPs/g-C3N4 materials exhibit superior photocatalytic activity compared to the pristine g-C3N4. The studies on the influence of free radicals and photogenerated holes, h+, show that ˙OH, O2˙-, and h+ play decisive roles in the photocatalytic activity of AgNPs/g-C3N4. The TOC result indicates the minimal toxicity of the by-products formed during the 2,4-D degradation. In addition, the AgNPs/g-C3N4 catalytic activity under direct sunlight irradiation was similar to that under artificial UV irradiation. Based on these results, a possible mechanism is proposed to explain the enhanced photocatalytic activity and stability of AgNPs/g-C3N4. Theoretical calculations on the interaction between 2,4-D and g-C3N4, Ag/g-C3N4 was also performed. The calculated results show that the adsorption of 2,4-D on Ag-modified g-C3N4 is significantly more effective compared to pristine g-C3N4.

Insights into Plastic Degradation Processes in Marine Environment by X-ray Photoelectron Spectroscopy Study.

The present study employs X-ray photoelectron spectroscopy (XPS) to analyze plastic samples subjected to degradation processes with the aim to gain insight on the relevant chemical processes and disclose fragmentation mechanisms. Two model plastics, namely polystyrene (PS) and polyethylene (PE), are selected and analyzed before and after artificial UV radiation-triggered weathering, under simulated environmental hydrodynamic conditions, in fresh and marine water for different time intervals. The object of the study is to identify and quantify chemical groups possibly evidencing the occurrence of hydrolysis and oxidation reactions, which are the basis of degradation processes in the environment, determining macroplastic fragmentation. Artificially weathered plastic samples are analyzed also by Raman and FT-IR spectroscopy. Changes in surface chemistry with weathering are revealed by XPS, involving the increase in chemical moieties (hydroxyl, carbonyl, and carboxyl functionalities) which can be correlated with the degradation processes responsible for macroplastic fragmentation. On the other hand, the absence of significant modifications upon plastics weathering evidenced by Raman and FT-IR spectroscopy confirms the importance of investigating plastics surface, which represents the very first part of the materials exposed to degradation agents, thus revealing the power of XPS studies for this purpose. The XPS data on experimentally weathered particles are compared with ones obtained on microplastics collected from real marine environment for investigating the occurring degradation processes.

Floating MIL-88A(Fe)@expanded perlites catalyst for continuous photo-Fenton degradation toward tetracyclines under artificial light and real solar light

In this work, MIL-88A(Fe) was immobilized onto the expanded perlites to fabricate the floating MIL-88A(Fe)@expanded perlites (M@EP) catalyst via high throughput batch synthesis method under room temperature. The as-prepared M@EP could efficiently activate H2O2 to achieve 100% tetracycline antibiotics (TCs) removal under both artificial low power UV light (UVL) and real sunlight (SL) irradiation. The toxicological evaluation, growth experiment of mung beans and antimicrobial estimation revealed the decreasing aquatic toxicity of the TCs intermediates compared to those of the pristine TCs. A self-designed continuous bed reactor was employed to investigate the long-term operation of the M@EP. The findings demonstrated that the antibiotics mixture can be continuously degraded up to 7 days under UVL and 5 daytimes under SL irradiation, respectively. More importantly, ca. 76.9% and 81.6% of total organic carbon (TOC) removal efficiencies were accomplished in continuous bed reactor under UVL and SL irradiation, respectively. This work advances the immobilized MOFs on floating supports for their practical application in large-scale wastewater purification through advanced oxidation processes. Environmental implicationThis work presented the high throughput production and photo-Fenton degradation application of floating MIL-88A(Fe)@expanded perlites (M@EP). Three tetracycline antibiotics (TCs) were selected as model pollutants to test the degradation ability of M@EP in batch experiment and continuous operation under artificial light and solar light. The complete TCs degradation could be accomplished in self-designed device up to 7 d under UV light and 5 d under real solar light. This work tapped a new door to push MOFs-based functional materials in the real water purification.

Neurotoxicity of Benzotriazole Ultraviolet Stabilizers in Teleost Fishes: A Review.

Plastic additives that maintain integrity have been extensively studied for potential toxicity to fish; however, chemicals that protect polymers from (artificial) UV degradation are less studied. Benzotriazole UV stabilizers (BUVSs) are the most widely used UV stabilizers in plastics and are often used in sunscreens, cosmetics, paint, and food packaging. BUVSs can negatively affect aquatic wildlife when released into the environment via plastic degradation. In this review, we summarize the distribution of BUVSs globally and discuss neurotoxicological endpoints measured in fish to understand how these plastic additives can affect the neurological health of teleost fishes. BUVSs have been detected in aquatic environments at concentrations ranging from 0.05 up to 99,200 ng/L. Studies show that BUVSs affect behavioral responses and acetylcholinesterase activity, indicators of neurotoxicity. Our computational analysis using transcriptome data suggests certain pathways associated with neurodegeneration are responsive to exposure to BUVSs, like "Complement Activation in Alzheimer's Disease". Based on our review, we identify some research needs for future investigations: (1) molecular studies in the central nervous system to define precise mechanisms of neurotoxicity; (2) a wider range of tests for assessing aberrant behaviors given that BUVSs can affect the activity of larval zebrafish; and (3) histopathology of the nervous system to accompany biochemical analyses. These data are expected to enhance understanding of the neurotoxicity potential of benzotriazoles and other plastic additives.

Photocatalytic Degradation Using TiO2 P25: A Comparative Study for Different Textile Dyes

The photocatalytic degradation of textile dyes using metallic oxides has been extensively studied due to the remarkable results. This promising approach offers a more sustainable alternative for treating textile effluents contaminated with dyes and other chemicals, intending to mitigate the environmental impact caused by the textile industry. In this context, this study aimed to investigate the degradation of different classes of synthetic dyes used in industry through the heterogeneous photocatalysis process. For this purpose, TiO2 P25 dispersed in an aqueous dye medium exposed to an isolated source of artificial UV light was used. The significance of this research lies in understanding photodegradation phenomena and studying heterogeneous catalysis mechanisms applied to the degradation of textile dyes. Furthermore, the importance of sustainability in the textile industry is highlighted, emphasizing the need for new solutions to reduce waste emissions. This study contributes significantly to understanding the degradation of textile dyes through photodegradation, providing detailed information on the reaction processes and key factors influencing the efficiency of TiO2-catalyzed degradation. The results demonstrate real application potential and support sustainable strategies for treating textile effluents, aiming to reduce the environmental impact caused by dyes.

Laser flash photolysis and quantum chemical studies of UV degradation of pharmaceutical drug chloramphenicol: Short-lived intermediates, quantum yields and mechanism of photolysis

Using methods of time-resolved and stationary photolysis, HPLC-MS and quantum-chemical calculations by the DFT method, the mechanism of direct UV photolysis of the antibiotic chloramphenicol (CAP) was established. For the first time, short-lived intermediates formed during photolysis were detected. The primary photoprocess is the cleavage of the β-C-C bond relative to the aromatic system with the formation of 4-nitrobenzylalcohol radical and residual aliphatic radical. The first radical in deoxygenated solutions predominantly transforms into para-nitrobenzaldehyde and its secondary photolysis products. In the presence of oxygen, the aromatic radical and para-nitrobenzaldehyde are transformed into para-nitrosobenzoic and para-nitrobenzoic acids as a result of reaction with reactive oxygen species (ROS). Formation of ROS is provoked by reactions of aliphatic radical with dissolved oxygen, so this radical is very important for CAP degradation. The quantum yield of direct photolysis of CAP is ∼3% and does not depend on the presence of dissolved oxygen and on the change of the excitation wavelength in the range of 254–308 nm. Obtained data are important for further understanding of the transformation pathways of CAP and similar PPCP in natural and wastewaters under the action of sunlight and artificial UV radiation.

Multi-wavelength and broadband AlGaN-based LED for versatile and artificial UV light source

This study focuses on modeling and analyzing a multi-wavelength (MW) ultraviolet light-emitting diode (UV LED) equipped with grading transition layers, which holds potential as a versatile and artificial UV light source. Commencing with the exploration of simple dual and triple-wavelength UV LEDs, we delve into the device mechanism, including the role of the grading transition layer and the control of emission intensity ratios. The grading transition layer connects modules with different emission wavelengths, effectively enhancing hole injection by diminishing the effective hole barrier and providing three-dimensional hole gas (3DHG). Besides, the emission intensity ratio of different modules is modulated through electron overflow, which is finely and coarsely controlled respectively by altering the quantum well number and the Al composition of electron controlling layers (ECLs). Modulating the ECL composition and quantum well number has good unilaterality facilitated by using grading transition layers, promoting a lower overall design complexity. Band diagrams, current dynamics, and carrier concentration distribution are analyzed to uncover various device mechanisms. After investigating dual-wavelength and triple-wavelength LEDs, a broadband UV LED is designed and demonstrated through the numerical method. The LED incorporates five emission modules, and each module has a similar emission intensity, contributing to a near 100 nm width UV spectrum. We expect this work lays the foundation for MW and broadband UV LED designs, fostering advancements in the AlGaN-based UV LED community.

Impact of heliotherapy and phototherapy on the course of atopic dermatitis

Introduction and purpose. Atopic dermatitis (AD) is a common chronic inflammatory skin disease that affects many children and adults around the world. It has been also empirically known that some environmental factors such as exposure to the sun can be beneficial for patients with AD. The purpose of this literature review is to present positive impact, as well as challenges and risks of heliotherapy and phototherapy on patients suffering from AD.
 Material and methods. The article is a review of publications obtained from the PubMed database and published between 2017-2023. Based on the keywords "phototherapy" "heliotherapy"and "atopic dermatitis", 14 articles were selected. Finally, 1 meta-analysis and 3 observational studies were included in the rewiev.
 Brief description of the state of knowledge. People with AD have a compromised skin barrier, which favors infiltration by activated Th2 cells, and their cytokine, causing thickening of the skin. It makes management of AD challenging. It is known that most patients’ skin condition improves due to sun exposure. This is why an artificial UV radiation (UVR) is employed for the treatment. The idea is to administrate a non-ionizing radiation to the skin. Both sunlight and artificial light have a significant immunosuppressive effect on the skin.
 Summary. Phototherapy as well as heliotherapy improved skin condition of people suffering from AD. It was appreciable by the end of few weeks of studies and also afer 3 months, reflected by improvement in PO-SCORAD, VAS and DLQI scales. During some of the studies there have been incidents of side-effects. More research is necessary to define a long-term effect of this kind of treatment and the role of chronic and prolonged therapy of AD.

Lifetime considerations of geotextile UV exposure before installation

Geotextile are in most case intended for buried application, without exposure to sunlight. However, a short exposure to sunlight may occur before installation. Because of potential delay of installation and soil burying, the material is required to meet UV resistance. Artificial UV weathering will assess the potential risk of unintended exposure to sunlight. Photodegradation reactions consider the interactions with exposure conditions as well as polymer sensitivity to sunlight. Based on both laboratory measurements and field data, this paper evaluates the effect of light intensity, temperature and humidity with climates. Using polymer relation of its UV light sensitivity with the effective irradiance, a cumulative index is calculated for the reduction of geotextile service life from exposure to sunlight. Artificial weathering cycles for geotextiles are compared and related to the specific degradation mechanisms of polypropylene and polyethylene terephthalate. The reaction rate is correlated with temperature, respectively for each polymer. A model using radiant energy and temperature is proposed for guidance to service life prediction of partly UV-exposed geotextiles.

CuO/ZnO Type-II heterojunction modified by rGO nanosheets for improved photocatalytic mineralization of antibiotics

In the present work, CuO/ZnO type-II heterojunction was modified by graphene oxide nanosheets for excellent photocatalytic mineralization of antibiotics under artificial UV light and natural sunlight. For this purpose, CuO/ZnO heterojunction-graphene oxide nanocomposites were synthesized via a facile refluxing method in aqueous media. The synthesized nanocomposites were characterized through diverse characterization techniques such as XRD, FT- IR, Raman, SEM, TEM, and UV–Vis DRS to determine their structural, morphological, and optical properties. XRD analysis confirmed the monoclinic CuO and hexagonal wurtzite ZnO phase in bare CuO/ZnO heterojunction and different CuO/ZnO heterojunction-graphene oxide nanocomposites as well. The optical band gap was found in the range of 3.06–3.19 eV for different nanocomposites. The photocatalytic activity of the bare heterojunction and nanocomposites was performed against the degradation of ciprofloxacin under the irradiation of artificial UV and natural sunlight as well. The highest degradation % of ciprofloxacin was achieved at 96.27 % and 76.44 % under artificial UV and natural sunlight within 120 min, respectively over CuO/ZnO heterojunction with 3 wt% of graphene oxide. The outstanding photocatalytic performance of CuO/ZnO heterojunction-graphene oxide (3 wt%) owing to the high adsorption capacity and synergism between CuO/ZnO and graphene oxide caused the improved separation of charge species resulting higher production rate of reactive oxygen species and prompt degradation of ciprofloxacin.

Degradation of Paracetamol in Distilled and Drinking Water via Ag/ZnO Photocatalysis under UV and Natural Sunlight

The present study demonstrates the synthesis and application of Ag/ZnO powder films (thickness of 4 μm) as photocatalysts for natural sunlight and ultraviolet (UV, 315–400 nm) irradiation. The synthesis procedure is simple and eco-friendly, based on the photo-fixation of silver ions onto commercial ZnO powder via UV illumination for the first time. The photocatalytic efficiency of the newly developed films is evaluated through degradation of paracetamol in distilled and drinking water. Our experimental evidences show that the Ag/ZnO nanostructure films are more active than pristine ZnO films in the photodegradation process. Namely, the photocatalytic efficiency of the films modified with 10−2 M concentration of silver ions achieve the highest degradation (D) percentages for paracetamol in both types of water (Ddistilled = 80.97%, Ddrinking = 82.5%) under natural sunlight. Under UV exposure, the degradation percentages are slightly lower but still higher than those achieved by pure ZnO films (Ddistilled = 53.13%, Ddrinking = 61.87%). It is found that the photocatalytic activity grows in direct proportion to the concentration of Ag+ ions: ZnO < Ag 10−4/ZnO < Ag 10−3/ZnO < Ag 10−2/ZnO. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance and photoluminescence spectroscopy are used to characterize the as-prepared ZnO and Ag/ZnO nanostructures. The improved photocatalytic performance of the Ag/ZnO films is mostly attributed to the combination of excited electron transfer from ZnO to Ag and the inhibition of photogenerated electron–hole pair recombination. Furthermore, Ag/ZnO nanostructure films can retain their photocatalytic activity after three cycles of use, highlighting their potential practical application for the treatment of pharmaceutical wastewater in real-world scenarios where natural sunlight is often more readily available than artificial UV light.

UV Dosage Unveils Toxic Properties of Weathered Commercial Bioplastic Bags.

Previous studies indicated that weathered conventional plastics and bioplastics pose ecotoxicological risks. Here, the effects of artificial and natural weathering on the ecotoxicity of three compostable bags and a conventional polyethylene (PE) bag are investigated. With that aim, a 21-day artificial indoor weathering experiment featuring UV light, UV-filtered light, and darkness was run simultaneously to a 120-day outdoor littoral mesocosm exposure featuring natural light, UV-filtered light, and shaded conditions. Acute toxicity of so-weathered plastic specimens was tested in vivo using the sensitive Paracentrotus lividus sea-urchin embryo test. PE was nontoxic from the beginning and did not gain toxicity due to UV weathering. In contrast, for bioplastics, dry artificial UV weathering increased toxicity in comparison to the dark control. Weathering in outdoor mesocosm led to a rapid loss of toxic properties due to leaching in rainwater. With a higher UV dosage, a plastic-type-dependent regain of toxicity was observed, most likely driven by enhanced availability or transformation of functional additives or due to bioplastic degradation products. PE showed moderate UV absorbance, while bioplastics showed high UV absorbance. This study highlights the potential of biodegradable plastics to pose enhanced ecotoxicological risk due to weathering under environmentally relevant conditions.

Green Synthesis of Novel Antimicrobial ZnO Nanorods

Zinc oxide (ZnO) nanoparticles (NPs) are increasingly used in the diagnosis and prevention of various human infections and diseases. The multi-functional nature of these nanoparticles together with characteristics such as low toxicity and biodegradability, allow their use in a slew of products and applications ranging from biomedical, food and supplement industries, therapeutics and biosensors. ZnO exhibits biomimetic properties enabling biomedical applications, including use as alternatives to pre-existing antibiotics. This study discusses a simple, cost-effective and environmentally sustainable technique for the synthesis of crystalline ZnO nanorods from egg-white or albumin. Single phase nature of the of the engineered nanocrystals was determined using X-ray diffraction (XRD) and selected area electron diffraction (SAED) technique. The morphology of the ZnO nanorods was studied using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The diameter of synthesized ZnO nanorods was determined to be in the range of 20–30 nm. The crystal structure of wurtzite ZnO was discovered by the use of Raman, FTIR, while the surface area (12.8 m2/g) was analyzed by using Brunauer-Emmett-Teller (BET) surface area study. Both gram-positive and gram-negative bacterial strains were used to test the ZnO nanorods’ antibacterial abilities without the need of artificial UV activation. Findings showed that different disease-causing bacteria present in community and hospital settings respond differently to ZnO nanorods’ antibacterial activity. When the concentration of nanorods powder increased, the ratio of bacterial survival dropped, showing an increase in antibacterial activity. The gram-negative strain Pseudomonas aeruginosa was shown to have the maximum antibacterial activity of the ZnO nanorods as compared to other gram-negative and positive bacteria. Eco-friendly and green synthesis of ZnO NPs produce vital multifunctional nanomaterials which possess promising antibacterial properties with more extensive studies may develop drugs for multidrug resistance bacteria.

Effect of Melanin on the Stability of Casein Films Exposed to Artificially Accelerated UV Aging

Petroleum-based polymer food packaging is causing increasing concern. Their biopolymer alternatives should have some added value to compete with them and push them out of the market. This article presents new information related to the effects of melanin on casein films and their protection against artificial UV aging. Casein films were modified with melanin as an active additive and then subjected to artificial aging using UV radiation to evaluate its effect on the preservation of the films’ properties. The films were tested for hydrological (moisture content and water solubility), mechanical, barrier against UV-Vis radiation, colorimetric, and antioxidant properties, and the content of free amino acids and sulfhydryl and disulfide groups were checked before and after aging. Melanin influenced the preservation of mechanical properties of the films (elongation at break increased by no more than 20% for melanin-modified samples compared to more than 50% increase for the control sample), better UV barrier properties, increased antioxidant properties (two-fold higher scavenging of DPPH radicals by films modified with the highest melanin content compared to unmodified films before aging, and four times higher scavenging of DPPH radicals after aging). In addition, the presence of melanin had protective properties for sulfhydryl bonds and proteins (the increase in free amino acids after aging for melanin-modified films was not statistically significant), and it also had the effect of increasing the abundance of bands corresponding to oligomers and polymers in electrophoretic separation. The results indicate that melanin has UV-protecting properties on casein films, and it can be assumed that the obtained casein films modified with melanin could potentially find application as food packaging or edible coatings.

Impact of UV Irradiation on the Chitosan Bioactivity for Biopesticide Applications.

Chitosan is known for its antimicrobial and antifungal properties that make it a promising candidate for plant protection. However, when sprayed in open fields, the bioactivity of chitosan significantly diminishes, suggesting a possible influence of sunlight on chitosan structure. This study aimed to investigate the effects of UV radiation, by using artificial UV sources simulating sunlight, on the stability of chitosan. A powdered chitosan with a low polymerization degree was selected and analyzed using various physicochemical methods, both before and after irradiation. Some minor differences appeared. UV spectra analysis revealed the disappearance of initially present chromophores and the emergence of a new band around 340 nm, potentially indicating the formation of carbonyl compounds. However, elemental analysis, MALDI-TOF spectra, polymerization degree, and infrared spectra did not exhibit any clear structural modifications of chitosan. Interestingly, irradiated powdered chitosan samples maintained their bioactivity, including their eliciting and antifungal properties. In the case of grapevine, irradiated chitosan demonstrated effectiveness in controlling grapevine diseases such as downy mildew, contradicting the assumption that sunlight is responsible for the decreased effectiveness of chitosan in open field conditions.

Sunlight and marine weathering of poly(oxymethylene): Evolution of the physico-chemical properties

Plastic pollution is now an environmental problem that affects all environmental compartments. The study of plastic degradation in terrestrial, marine and other freshwater environments is emerging. Research is mainly focused on plastic fragmentation into microplastics. In this contribution, an engineering polymer, poly(oxymethylene) (POM), was studied under different weathering conditions using physico-chemical characterization techniques. A POM homopolymer and a POM copolymer were characterized by electron microscopy, tensile tests, DSC, infrared spectroscopy and rheometry tests after climatic and marine weathering or artificial UV/water spray cycles. Natural climatic conditions were the most favorable for POM degradation, especially under solar UV, as evidenced by the strong fragmentation into microplastics when subjected to artificial UV cycles. The evolution of properties with exposure time was found to be non-linear under natural conditions, in contrast to artificial conditions. Two main stages of degradation were evidenced by the correlation between strain at break and carbonyl indices.