UVA Irradiation Research Articles

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.

Abstract 273: Extrinsic photoaging vs intrinsic aging in dermal fibroblasts: Its impact on the microenvironment and melanoma progression

Abstract Melanoma is the deadliest form of skin cancer, with chronological aging as a major negative prognostic factor due to the influence of intrinsic aging on the tumor microenvironment (TME) to promote tumor initiation and progression. Ultraviolet radiation (UVR) exposure, which is a major risk factor for melanoma, also can cause a physical premature aging phenotype, known as extrinsic photoaging, from chronic UVA irradiation of the underlying dermis. Photoaging of the skin often occurs in tandem with chronological aging, and contributes to similar physical alterations in normal skin structure. However, the molecular mechanisms of how photoaging compares to chronological aging in changing the TME and on tumor progression is still lacking. Here we found that extrinsically photoaged fibroblasts have a higher level of secretion of lysosomal proteases, Cathepsins, which have been shown to be secreted via lysosomal exocytosis and play a functional role in extracellular matrix (ECM) remodeling at neutral PH levels. We found that Cathepsins B and D are secreted at higher levels in both extrinsically photoaged young fibroblasts and in intrinsically aged fibroblasts and upregulated at the endogenous protein level. Cathepsin B has been shown to be highly expressed in metastatic but not primary melanoma patient samples, and cleaves ECM proteins such as fibronectin and tenascin. Immunofluorescent staining of in-vitro fibroblast derived matrices (CDMs) confirmed that photoaging disrupts subsequent deposited extracellular matrix proteins similarly to that of intrinsically aged healthy fibroblasts and these matrix changes influences the growth pattern of melanoma lines plated on these CDMs. Mass spectrometry analysis of secreted proteomics confirmed that aged fibroblasts secrete more cathepsins than intrinsically young fibroblasts, and Cathepsins B and D were also detected in extracellular vesicle (EV) cargo proteomics. Single-Particle Interferometric Reflectance Imaging (SP-IRIS) of EVs showed that UVA irradiation induced a significant increase in the total number of secreted of exosomes and in expression of tetraspanin protein CD63, which plays a role in cargo sorting and has been detected in high levels in the plasma of melanoma patients. We hypothesize that extrinsic photoaging of fibroblasts induces the secretion of exosomes packaged with Cathepsins that play an integral role in ECM remodeling and matrix degradation in a beneficial manner for melanoma invasion. Further studies will assess the influence on secreted cathepsins on melanomagenesis and melanoma invasion through both mechanical and biochemical changes in the TME with in-vitro and in-vivo studies. Citation Format: Vania Wang, Yash Chhabra, Laura Hueser, Ashani Weeraratna. Extrinsic photoaging vs intrinsic aging in dermal fibroblasts: Its impact on the microenvironment and melanoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 273.

Anti-Aging Properties of Cannabis sativa Leaf Extract against UVA Irradiation

Hemp extract has garnered interest as a potential cosmeceutical agent with multifunctional activities, particularly in protecting against UV-induced skin cell aberrations and restoring aged skin cells. The ethanolic extract of Cannabis sativa leaves was prepared into an aqueous solution (CLES) to investigate its anti-photoaging ability. HPLC analysis revealed that the CLES contained 1.64 ± 0.01% w/w of cannabidiol and 0.11% w/w of ∆9-tetrahydrocannabinol. Additionally, the total phenolic content was found to be 4.08 ± 0.30 mg gallic acid equivalent per g of solution using the Folin–Ciocalteu method. The CLES exhibited potent scavenging activity using a DPPH assay, with an EC50 value of 277.9 ± 2.41 μg/mL, comparable to L-ascorbic acid, with 2.19 ± 0.28 μg/mL. The anti-photoaging potential of the CLES was evaluated using UVA-irradiated and in vitro-aged fibroblasts as a model. Pre-treatment with 20 μg/mL CLES for 24 h significantly alleviated the reduction in type I procollagen and suppressed the overproduction of MMP-1 and IL-6 induced by UVA. Moreover, the percentage of senescence-associated β-galactosidase-expressing cells decreased significantly to 11.9 ± 0.5% in the aged cells treated with CLES compared with untreated cells (18.8 ± 3.8%). These results strongly indicate the cosmeceutical potential of the CLES as an effective active agent for the anti-photoaging prevention and/or treatment.

The enhanced visible-light-driven photocatalytic performance of nanocrystalline TiO2 decorated by quinazolinone-photosensitizer toward photocatalytic treatment of simulated wastewater

Semiconductor-assisted photocatalysis is an efficient, green, low-cost technology employed for wastewater treatment. TiO2-based photocatalysts are the common photocatalysts; however, their large bandgap energy excludes their photocatalytic activities under UV irradiation. Hence, this work investigates the synthesis of quinazolinone photosensitizer to improve the photocatalytic activity of TiO2 in the visible region and efficiently maximize the utilization of solar irradiation. Quinazolinone photosensitizer is a heterocyclic compound exhibits a wide spectrum in the visible region. The prepared samples are characterized by XRD, FE-SEM, FTIR, DRS, and PL. The photocatalytic activity of the Quinazolinone photosensitized-TiO2 catalyst is evaluated toward the degradation of rhodamine B (RB) as a model of organic pollutants in wastewater under UV-A and visible light irradiations. Quinazolinone photosensitized-TiO2 catalyst exhibited a wider absorption spectrum range and lower bandgap of 2.65 eV extending its activity to the visible region compared to bare TiO2 (3.00 eV). Control tests and factors affecting the photocatalytic degradation rate of RB dye such as pH of the medium, dye concentration and catalyst dose are investigated. Degradation of RB follows 1st-order kinetics. The mechanism of degradation is described based on trapping experiments.

Zeofilters for potentially innovative sunscreen products: formulation, stability and spectroscopic studies

Exposure to both UVA and UVB radiation from the sun stands as the primary cause of skin cancers, contributing to the escalating yearly count of diagnosed cases. Sunscreen products, (i.e. organic and inorganic UV filters) have become ubiquitous in personal-care products, packaging, plastics, dyes, and many other sectors. Ideal UV filters should be photostable and dissipate the absorbed energy efficiently. However, most organic UV filters are photolabile upon protracted UV exposure, leading to the formation of photoproducts of unknown toxicity for human health and environment. The chemical environment surrounding UV filters may strongly affect their behaviour: the interaction with other components of sunscreen formulations may enhance their degradation. Particularly, the interaction between photochemically incompatible ingredients must be avoided. Therefore, much effort has been invested in developing more effective and safe sunscreens.Our team recently focused on the preparation and characterization of hybrid UVfs obtained by the encapsulation of organic UV filters into various zeolites differing for topology. The zeolite most efficient for the encapsulation of organic UV filters, in term of stability and efficiency in radiation filtration, resulted to be LTL zeolite. Here, hybrid materials realized after the encapsulation of octinoxate (OMC) and avobenzone (AVO) in LTL zeolite were tested in terms of skin permeation profiles, cytotoxicity and photostability once the materials are dispersed in cream formulations, so to mimicking the real condition of use.The results show that the hybrids were successfully incorporated into oil-in-water emulsions and the skin permeation tests displayed a very low UV filter permeation through pig skin and no UV filter accumulation in dermis layer.The photostability of the hybrid-based emulsions were compared with that of emulsions containing a mixture of bare OMC and AVO, highlighting a reduced decrease in UV screening efficiency upon irradiation for the samples containing the hybrid materials with respect to the free filters. This evidence confirms that the encapsulation in the zeolite frameworks prevents some of the photodegradation reactions. The result of this paper highlights that zeolite encapsulation is increasingly establishing as a viable way to stabilize UV filters and other photoactive molecules.

Disruptive Model That Explains for the Long-Lived Triplet States Observed for 2-Thiocytosine upon UVA Radiation.

The possible role of radical species in the formation of the long-lived triplet states observed for 2-thiocytosine upon UV irradiation was theoretically investigated. It is predicted that the radical fragments arising from the homolytic rupture of the NH group of the thiobase can be yielded upon ultraviolet-A radiation. Recombination of the radicals through the most favorable singlet channel yields the lowest-lying tautomer of the 2-thiocytosine (the amino-thiol form) through a barrierless pathway. The rebounding of the radical fragments along the triplet channels that emerge from the attack of the hydrogen to the nitrogen atoms next to the C-S bond leads to stable structures for the amino-thion-N1H and amino-thion-N3H tautomers. These results allow for the rationalization of the near-unity triplet yields observed when this pure light-atom organic molecule is exposed to UV irradiation, without invoking intersystem crossings between the electronic states of different spin-multiplicities. A similar study for cytosine showed that the energy required to induce the homolytic breaking of the N-H bond of the nucleobase is not attainable under UVA radiation. This result is consistent with the experimental fact that no triplet states are observed when this molecule is exposed to that light.

Spectroscopic view on the interaction between the psoralen derivative amotosalen and DNA

Psoralens are eponymous for PUVA (psoralen plus UV-A radiation) therapy, which inter alia can be used to treat various skin diseases. Based on the same underlying mechanism of action, the synthetic psoralen amotosalen (AMO) is utilized in the pathogen reduction technology of the INTERCEPT® Blood System to inactivate pathogens in plasma and platelet components. The photophysical behavior of AMO in the absence of DNA is remarkably similar to that of the recently studied psoralen 4′-aminomethyl-4,5′,8-trimethylpsoralen (AMT). By means of steady-state and time-resolved spectroscopy, intercalation and photochemistry of AMO and synthetic DNA were studied. AMO intercalates with a higher affinity into A,T-only DNA (KD = 8.9 × 10−5 M) than into G,C-only DNA (KD = 6.9 × 10−4 M). AMO covalently photobinds to A,T-only DNA with a reaction quantum yield of ΦR = 0.11. Like AMT, it does not photoreact following intercalation into G,C-only DNA. Femto- and nanosecond transient absorption spectroscopy reveals the characteristic pattern of photobinding to A,T-only DNA. For AMO and G,C-only DNA, signatures of a photoinduced electron transfer are recorded.Graphical abstract

The REV-ERB antagonist SR8278 modulates keratinocyte viability in response to UVA and UVB radiation.

The nucleotide excision repair (NER) system removes UV photoproducts from genomic DNA and is controlled by the circadian clock. Given that small-molecule compounds have been developed to target various clock proteins, we examined whether the cryptochrome inhibitor KS15 and REV-ERB antagonist SR8278 could modulate keratinocyte responses to UV radiation invitro. We observed that though SR8278 promoted cell viability in UVB-irradiated cells, it had little effect on NER or on the expression of the clock-regulated NER factor XPA. Rather, we found that both KS15 and SR8278 absorb light within the UV spectrum to limit initial UV photoproduct formation in DNA. Moreover, SR8278 promoted UVB viability even in cells in which the core circadian clock protein BMAL1 was disrupted, which indicates that SR8278 is likely acting via other REV-ERB transcriptional targets. We further observed that SR8278 sensitized keratinocytes to light sources containing primarily UVA wavelengths of light likely due to the generation of toxic reactive oxygen species. Though other studies have demonstrated beneficial effects of SR8278 in other model systems, our results here suggest that SR8278 has limited utility for UV photoprotection in the skin and will likely cause phototoxicity in humans or mammals exposed to solar radiation.

Photoinactivation by UVA radiation and visible light of Candida auris compared to other fungi.

In addition to the rising number of patients affected by viruses and bacteria, the number of fungal infections has also been rising over the years. Due to the increase in resistance to various antimycotics, investigations into further disinfection options are important. In this study, two yeasts (Candida auris and Saccharomyces cerevisiae) and a mold (Cladosporium cladosporioides) were irradiated at 365, 400, and 450nm individually. The resulting log 1 reduction doses were determined and compared with other studies. Furthermore, fluorescence measurements of C. auris were performed to detect possible involved photosensitizers. A roughly exponential photoinactivation was observed for all three fungi and all irradiation wavelengths with higher D90 doses for longer wavelengths. The determined log 1 reduction doses of C. auris and S. cerevisiae converged with increasing wavelength. However, S. cerevisiae was more photosensitive than C. auris for all irradiation wavelengths and is therefore not a suitable C. auris surrogate for photoinactivation experiments. For the mold C. cladosporioides, much higher D90 doses were determined than for both yeasts. Concerning potential photosensitizers, flavins and various porphyrins were detected by fluorescence measurements. By excitation at 365nm, another, so far unreported fluorophore and potential photosensitizer was also observed. Based on its fluorescence spectrum, we assume it to be thiamine.Graphic abstract.

BSA Adsorption on Titanium Dioxide Nanoparticle Surfaces for Controlling Their Cellular Uptake in Skin Cells.

Nanoparticles (NPs) are continuously being developed for many applications including imaging, biomedicine, and everyday products. It is difficult to avoid contact with NPs such as titanium dioxide (TiO2) NPs, which are widely used in sunscreens. However, the safety of TiO2 NPs for skin contact and inhalation remains controversial. If NPs cannot penetrate the skin, they will be unable to circulate in the bloodstream, accumulate in the body, or cause side effects, ensuring their safety. Therefore, this study aimed to modify TiO2 NP surfaces to inhibit their uptake in skin cells. Inspired by protein corona studies, bovine serum albumin (BSA) was chosen to functionalize TiO2 NP surfaces via physical adsorption. The maximum BSA adsorption occurred at pH 5.0. The physicochemical properties (size, ζ-potential, morphology, ultraviolet (UV) absorption efficiency, and sun protection factor (SPF)) of TiO2-BSA NPs were comparable to those of TiO2 NPs, indicating that these properties did not affect cellular uptake. In the safety evaluation, TiO2 NPs and TiO2-BSA NPs exhibited high biocompatibility with skin cells and no phototoxicity after UVA and UVB irradiation. In the efficacy evaluation, both NPs possessed the same photoprotection abilities, reducing membrane damage and DNA breakage after UVA irradiation. Compared with TiO2 NPs, TiO2-BSA NPs showed substantially reduced skin penetration in Franz diffusion cells (91%) and human immortalized keratinocyte (HaCaT) cells (89%). A qualitative cellular uptake study using transmission electron microscopy and confocal laser scanning microscopy confirmed that TiO2 NPs were more abundant than TiO2-BSA NPs inside the HaCaT cells. These findings indicate that TiO2 surface functionalization with BSA inhibits cellular uptake in skin cells while maintaining safety and UV protection efficacy, which might be extended to other NP-based sunscreens.

Oxygen-supplemented and topography-guided epithelium-on corneal crosslinking with pulsed irradiation for progressive keratoconus.

To investigate the effects of customized topography-guided epithelium-on crosslinking (epi-on CXL) with oxygen supplementation on procedural efficacy and corrected distance visual acuity (CDVA) in patients with progressive keratoconus (KC) at 1 year. Private eye clinic, Brisbane, Australia. Retrospective, single-center, nonrandomized case series. Topography-guided epi-on CXL using the Mosaic system was performed on patients with progressive KC. Oxygen goggles; transepithelial riboflavin; and pulsed, high UV-A irradiance (1 second on, 1 second off; 30 mW/cm2) were applied to enhance oxygen kinetics and bioavailabilities of riboflavin and UV-A. Guided by baseline topography, a higher UV-A dose (15 J/cm2) was applied to the area of steepest anterior curvature with decreasing fluence (as low as 7.2 J/cm2) toward the outer 9 mm. Postoperative CDVA and maximum keratometry (Kmax) were evaluated. 102 eyes (80 patients) were followed for 11.5 ± 4.8 months. At the latest follow-up, mean CDVA (logMAR), mean K, and Kmax (diopters [D]) improved from 0.18 ± 0.28, 46.2 ± 3.8, and 53.0 ± 5.67 at baseline to 0.07 ± 0.18, 45.8 ± 3.7, and 51.9 ± 5.56, respectively (P < .001). 3 eyes (3%) lost more than 1 CDVA line, and another 3 eyes (3%) had increased Kmax greater than 2 D. 43 eyes were followed for at least 12 months (n = 43): mean CDVA, mean K, and Kmax improved from 0.19 ± 0.33 logMAR, 46.5 ± 3.5 D, and 53.6 ± 5.67 D to 0.07 ± 0.17 logMAR, 46.0 ± 3.5 D, and 52.33 ± 5.49 D, respectively (P ≤ .002). No complications were observed. Tailoring oxygen-supplemented epi-on CXL with differential UV-A energy distributions, guided by baseline topography, in patients with KC seems to be safe and effective. At 1 year, study reports sustained improved CDVA and corneal stabilization.

Comparison of the Regenerative Metabolic Efficiency of Lipid Extracts from Microalgae Nannochloropsis oceanica and Chlorococcum amblystomatis on Fibroblasts.

UVA radiation leads to oxidative stress and inflammation in skin cells. Therefore, the aim of this study was to compare the effect of lipid extracts from microalgae Nannochloropsis oceanica (N.o.) (marine) and Chlorococcum amblystomatis (C.a.) (freshwater) on the redox balance and PUFA metabolism in human skin fibroblasts modified by UVA. Lipid extracts from both types of microalgae introduced into the fibroblast medium after UVA irradiation significantly reduced the level of ROS and enhanced expression of Nrf2, which increased the activity/level of antioxidants (SOD1/2, CAT, GSH, Trx). The reduction in oxidative stress was accompanied by a decrease in the level of 4-HNE, its protein adducts and protein carbonyl groups. Microalgae also reduced the activity of COX1/2, FAAH and MAGL increased by UVA, and as a consequence, the level of lipid mediators (especially after N.o.) decreased, both from the group of endocannabinoids (AEA, 2-AG, PEA) and eicosanoids (PGE2, 15d-PGJ2, TXB2, 15-HETE), acting mainly through receptors related to G protein, the expression of which increases after UVA. This further contributed to the reduction in oxidative stress and pro-inflammatory signaling at NF-κB and TNFα levels. Therefore, it is suggested that lipid extracts from both N.o. and C.a. microalgae can be used to regenerate fibroblast metabolism disturbed by UVA radiation.

UV-A radiation increases biomass yield by enhancing energy flow and carbon assimilation in the edible cyanobacterium Nostoc sphaeroides.

Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.

Preparation of poly(methyl methacrylate)-zinc oxide hybrid nanoparticles via miniemulsion polymerization

The encapsulation of zinc oxide (ZnO) nanoparticles with poly(methyl methacrylate) in the presence of triethylene glycol dimethacrylate (TEGDMA) as a crosslinking agent was synthesized by the miniemulsion polymerization technique. The ZnO as a catalyze was varied from 1 wt% - 7 wt%. Several techniques were used to analyze the PMMA/TEGDMA/ZnO hybrid. The morphology and particle size distribution of the PMMA hybrid was observed using a field emission scanning electron microscope (FE-SEM). The diameter of the PMMA/TEGDMA/ZnO hybrid was in the range of 57 nm to 115 nm. The morphology of the PMMA/ZnO hybrids was sphere-shaped with a narrow particle size distribution and no agglomeration of the hybrids occurred. The encapsulation and crystalline structure of the PMMA ZnO hybrid were determined using a high-resolution transmission electron microscope (HR-TEM). The HR-TEM image demonstrated that the ZnO was encapsulated in the PMMA hybrid. In addition, the high magnification of the TEM image demonstrated the lattice spacing of ZnO and the diffraction mode image presented the crystalline structure of ZnO. Therefore, the photocatalytic properties of the PMMA/ZnO hybrid were examined via the degradation of methylene blue (MB) solution under dark and UV-A irradiation. It was found that the photocatalytic activities of the PMMA/ZnO hybrid increased when the ZnO content increased up to 7 wt%. The maximum MB degradation for PMMA/TEGDMA/ZnO 7 wt% and PMMA/ZnO 7 wt% were 80.1 % and 77.6 %, respectively. Thus, the photocatalytic efficiency of the PMMA/ZnO increased in the presence of TEGDMA as a crosslinking agent.

Effect of UV Stress on the Antioxidant Capacity, Photosynthetic Activity, Flavonoid and Steviol Glycoside Accumulation of Stevia rebaudiana Bertoni

Lighting conditions are an important controller of plant growth and development, and they affect secondary metabolite synthesis. In this research, we explored the effect of additional UV irradiation of various ranges in addition to the main one at PPFD 160 µmol m−2 s−1 on the accumulation of some secondary metabolites of stevia (Stevia rebaudiana Bertoni). The fresh weight of leaves was slightly higher under additional UV-A and UV-B irradiation compared with the control variant, and the leaf surface area was significantly larger, respectively, by 23.3 and 20.7% than in the control variant, while the rate of photosynthesis did not decrease. Plants under additional UV-B and UV-C irradiation were under the greatest light stress, as evidenced by a decrease in antioxidant capacity by an average of 30% compared to the control and UV-A. The total flavonoid content was significantly higher (by 74%) under UV-B irradiation. The highest concentration of steviol glycoside was observed during budding and flowering under UV-B and UV-C irradiation (by 13.2 and 11.3%, respectively). Analysis of hyperspectral images, chlorophyll fluorescence, and vegetation indices showed light stress increasing under UV-C irradiation, which caused an increase in the relative chlorophyll content, scorches, leaf morphology changes, a CO2 absorption rate decrease, and plant growth inhibition. UV-B irradiation can be used as an optimal type of irradiation based on a set of indicators.

Design of a new ZnO photocatalytic Fenton-like system for enhancing the removal of methylene blue at neutral pH

Although doping, nanostructuration, metallization, and binary/ternary oxide systems are widely used to improve the degradation kinetics in photocatalytic processes, rapid electron _ hole recombination remains one of its major limitations. On the other hand, homogeneous photo-Fenton-like processes suffer from the slow regeneration of Fe3+/Fe2+ catalysts and the formation of iron sludge at pH > 3. In this work, a new catalytic system is designed based on the coupling of nanostructured ZnO thin films photocatalysts with Fe3+/H2O2 (Fenton-Like) for the degradation of methylene blue (MB) molecules under UVA irradiation, at near-neutral pH (7.5). This coupled process promotes the formation of additional reactive oxygen species and reduces the formation of sludge by accelerating the regeneration of the iron catalysts in the medium. Furthermore, it exhibits a single kinetic regime of degradation with a rate constant of 0.0049 min−1 exceeding the sum of both individual processes and allowing therefore the removal of 94 % of MB after 480 min.

Application of electron paramagnetic resonance spectroscopy to examine free radicals formed in indapamide and torasemide storage under UV irradiation and at the higher temperatures which appear under light exposition

Free radical formation in two diuretics: indapamide and torasemide was examined during UV irradiation and storage at higher temperatures using X-band (9.3 GHz) electron paramagnetic resonance spectroscopy (EPR). The aim of this study was to investigate the possibility of storing indapamide and torasemide under UV irradiation and at higher temperatures, which may occur during exposure to light. The diuretic samples were exposed to UVA irradiation for 15, 30 and 45 minutes, and stored at temperatures of 40 °C and 50 °C by 30 minutes. The EPR spectra were analyzed to determine the amplitudes (A), linewidths (ΔBpp), and integral intensities (I) and g factors. The concentrations of free radical (N) in the diuretic samples were also determined. The influence of microwave power on amplitudes, linewidths and the asymmetry parameter were evaluated. The result showed that the tested indapamide and torasemide samples exhibited high free radical concentrations in the range of 1018-1019 spin/g after UV irradiation and heat treatment. Therefore, due to the significant free radical formation indapamide and torasemide should not be stored under UV light and at temperatures of 40 °C and 50 °C. The complex character of free radical systems in the diuretic samples was proved as evidenced by the changes of the asymmetry parameters of the EPR lines with increasing microwave power. Fast spin-lattice relaxation processes were observed in all tested diuretic samples, regardless of the storage conditions. Electron paramagnetic resonance spectroscopy is proposed as a useful method in pharmacy to determine the appropriate storage conditions for diuretics.

Effect of photons of the far red region in the spectrum of LED radiation on the growth and development of sugar beet plants (Beta &lt;i&gt;vulgaris&lt;/i&gt; L. ssp. &lt;i&gt;vulgaris&lt;/i&gt; var. &lt;i&gt;saccharifera&lt;/i&gt; Alef.)

Relevance and methodology. The task of controlling the growth and development of sugar beet plants with the help of lighting devices is of interest from the point of view of identifying biological features of the culture and in breeding practice. The purpose of the research is to determine the response of plants to the effects of low–energy monochrome radiation at the initial stage of ontogenesis (germination of seeds (coplodia) sugar beet). In this regard, the seeds of the hybrid Smena were germinated in the dark (control) and under different variants of continuous illumination with wavelengths of 380 nm, 440 nm, 525 nm, 660 nm and 730 nm.Results. The reaction of sugar beet seeds and sprouts to illumination with monochromatic light depends on the wavelength Germination of seeds when irradiated with monochromatic far-red light leads to a decrease in germination energy by 23%, seed germination by 39%, the height of sprouts and aboveground biomass by 21.8% compared with the control (dark germination). Similar indicators were observed for the negative effect of red light. Exposure to UV-A light (380 nm) led to an increase in germination energy by 4%, but germination, on the contrary, decreased by 12%. The terrestrial biomass of sprouts also decreased (by 9.9%). Irradiation with green and blue light had a positive effect on growth: the terrestrial biomass of sprouts increased by 19.8% with a green spectrum and 7.3% blue. At the same time, there was no decrease in germination energy and germination compared to the control. The germination energy under the influence of blue light even increased by 12%. With dark germination, elongated etiolated plants were formed on the 10th day, whereas in the variants of green, blue and UV-A irradiation, harmoniously developed dark green shoots were formed.

A Deep Insight into Perfluorooctanoic Acid Photodegradation Using Metal Ion-Exchanged Zeolites.

Treating perfluorooctanoic acid (PFOA) in an aqueous environment is problematic due to its low concentration and its high resistance to biological and chemical degradation. To tackle this challenge, combinations of pre-enrichment and photodegradation processes are promising solutions. In this work, we investigated metal ion-exchanged zeolites as adsorbents and photocatalysts for PFOA treatment. Among various transition metal ion-exchanged BEA zeolites, Fe-exchanged BEA (Fe-BEA) zeolites showed significant activity for the photodegradation of PFOA. The isolated iron species in Fe-BEA zeolite are responsible for PFOA photodegradation, whereas other iron species present from excess iron loading in the zeolite will lower its photocatalytic activity. Furthermore, it was proved via size exclusion tests using branched PFOA isomers that the photodegradation of PFOA took place on the internal surface rather than the external surface of Fe-BEA zeolite. Photodegradation of PFOA was also tested to be effective with Fe-exchanged BEA-type zeolites having various SiO2/Al2O3 ratios, but ineffective with FAU-type zeolites. The optimal Fe-BEA zeolite showed a sorption coefficient Kd of 6.0 × 105 L kg-1 at an aqueous phase PFOA concentration of 0.7 μg L-1 and a PFOA half-life of 1.8 h under UV-A irradiation. The presented study offers a deeper understanding of the use of metal ion-exchanged zeolites for photodegradation of PFOA.

Surfactants for stabilization of dermal emulsions and their skin compatibility under UVA irradiation: Diacyl phospholipids and polysorbate 80 result in high viability rates of primary human skin cells

Phospholipids are versatile formulation compounds with high biocompatibility. However, no data on their effect on skin in combination with UVA radiation exist. Thus, it was the aim of this work to (i) develop o/w nanoemulsions (NEs) differing in surfactant type and to investigate their physicochemical stability at different storage temperatures, (ii) establish a standardized protocol for in vitro phototoxicity testing using primary human skin cells and (iii) investigate the phototoxicity of amphoteric phospholipids (S45, S75, E80, S100, LPC80), sodium lauryl ether sulfate (SLES) and polysorbate 80 (PS80). Satisfying systems were developed with all surfactants except S100 due to low zeta potential (-21.4 mV ± 4.69). SLES and PS80-type NEs showed the highest stability after eight weeks; temperature-dependent variations in storage stability were most noticeable for phospholipid surfactants. For phospholipid-based NEs, higher phosphatidylcholine content led to unstable formulations. Phototoxicity assays with primary skin fibroblasts confirmed the lack of UVA-related phototoxicity but revealed cytotoxic effects of LPC80 and SLES, resulting in cell viability as low as 2.7 % ±0.78 and 1.9 % ±1.57 compared to the control. Our findings suggest that surfactants S45, S75 and PS80 are the most promising candidates for skin-friendly emulsifiers in sensitive applications involving exposure to UV light.