Search Results (586)

One of the most serious threats linked to the development of civilization is the growing amount of human-generated pollution released into the environment. These include volatile organic compounds (VOCs), a significant group of air pollutants found in all urban and industrial regions. They are characterized by high volatility, reactivity, and toxicity, which contribute to declining health in living organisms and to the formation of tropospheric ozone and photochemical smog. In this review, the sources of selected alcohols (i.e., methanol, ethanol) and toluene as the representative VOCs are discussed. Furthermore, the oxidation of these VOCs is reviewed over an important class of catalysts, which are multicomponent hydrotalcite-derived mixed metal oxides. The discussion about structure–property activity correlations is followed by a review of the most active and selective catalyst for each model molecule. Finally, the reaction mechanisms are discussed in the view of the existing literature, followed by the outcome. This review provides useful guidance for the rational design and development of advanced metal oxide catalysts for VOCs degradation, with particular relevance to practical industrial applications. Full article

Coastal humid-heat and photochemical-oxidant episodes are commonly studied through concentration estimation, leaving it unclear whether satellite observations improve warning decisions under explicit false-alarm constraints. This study introduces CoAST-EWS Japan, a six-station, validation-locked hindcast benchmark across Osaka Bay and Tokyo Bay. Models were developed using June–July 2023 data, calibrated and thresholded on August 2023 predictions, and retrospectively evaluated on June–August 2025 station-hour observations. The strong non-satellite route combines recent ground history, ERA5 meteorology, CAMS composition, and static station geometry. Adding previous-day MODIS thermal context to an otherwise identical XGBoost route increased average precision from 0.3153 to 0.3429, reduced the Brier score from 0.05032 to 0.04874, and improved recall/F1 under a validation-locked budget of 0.5 false alarms per station-day (FPDs) from 0.1864/0.2511 to 0.2402/0.3042. Japan-local calendar-day intervals supported the improvements in Brier score, recall, and F1. In a dimension-matched comparison using the same 18 MODIS variables, previous-day context increased average precision over the same-day route by 0.0378 (95% CI: 0.0144–0.0603), demonstrating that the timing advantage was not attributable to a larger satellite feature set. The MODIS increment was strongest during high-heat issue times and in Osaka Bay, and its ranking value was reproduced by a 36 h Temporal FLOW model. Matched spatial controls identified distance-based coastal context as the most stable 24 h graph component, while wind-aligned information operated as a complementary route. These results establish latency-aware MODIS thermal context as a measurable decision input for neighborhood-scale coastal compound warning. Strict station-level localization, cross-bay transfer, and forecast-consistent deployment define the next validation frontier. Full article

The combination of ultraviolet (UV) and periodate (PI) is a promising advanced oxidation process. We investigated the inactivation of a typical harmful algae species, Heterosigma akashiwo by UV/PI treatment and explored the inactivation mechanism at the cellular and molecular levels. The inactivation efficacy of H. akashiwo by UV/PI and UV treatment alone was 9.21-ln and 1.23-ln within 37.5 min, respectively. Hydroxyl radicals (•OH) and singlet oxygen (¹O₂) contributed to H. akashiwo inactivation in the UV/PI system. Obvious destruction of the cell structure observed by transmission electron microscopy and the increases in extracellular DNA levels indicated membrane damage by the reactive species. The activity changes in the antioxidant enzymes and the decreases in ATP contents of H. akashiwo after UV/PI treatment were both more severe than that after UV treatment. The results indicated that the antioxidant defense system and the mitochondria of H. akashiwo cells were disrupted. The photosynthesis was also affected as both of the chlorophyll-a content and the maximum dark-adapted photochemical efficiency (Fv/Fm) of H. akashiwo decreased obviously. The transcriptomics analysis proved that UV/PI treatment caused abnormal energy metabolism and cell function. Moreover, the down regulation of gene expression enriched in the phagocytic pathway indicated that the cell was severely damaged and inactivated under oxidative stress. Full article

Novel and efficient total syntheses of the nonsteroidal anti-inflammatory drugs Pelubiprofen and Loxoprofen via a photo-Favorskii rearrangement are reported herein. The key photochemical transformation was optimized under both batch and continuous-flow conditions using a suitably functionalized chloro-phenylpropan-1-one derivative, affording the target 2-arylpropionic acid in excellent yield. Implementation under continuous-flow conditions increased process productivity and enabled gram-scale operation. Aerobic oxidation of the benzylic position to the corresponding aldehyde, followed by Claisen–Schmidt condensation with cyclohexanone, afforded Pelubiprofen in 35% overall yield. Alternatively, condensation with cyclopentanone afforded the corresponding α,β-unsaturated enone intermediate, whose selective reduction under flow conditions enabled access to Loxoprofen in 28% overall yield. The versatility of the methodology was further demonstrated through the synthesis of Carprofen, highlighting the broader applicability of the photo-Favorskii rearrangement to the synthesis of APIs through previously unreported synthetic routes. Full article

Photo-induced reactions, also known as photochemical reactions, are chemical processes that are initiated or driven by the absorption of light energy. Photo-induced reactions have been applied in a variety of fields from organic synthesis to polymer curation. One such application of much current interest is additive manufacturing (AM)—a technique used within a variety of fields to produce intricately shaped components. Currently, additive manufacturing is utilized within the solar, medicine, electronic, and nuclear application industries, making it a diverse and expansive system of production. Present reviewed AM production methods include laser powder bed fusion (L-PBF), stereolithography (SLA), direct energy deposition (DED), and selective laser sintering (SLS). However, the literature points to the need for expansion of feedstock capabilities as the horizon broadens to extreme environments like nuclear reactors, a solution which might be found in photolytic reaction synthesis. This review examines photo-induced synthesis most applicable to additive manufacturing, focusing on four key reaction types: oxidation–reduction, combustion, decomposition and polymerization. Past and present applications, future challenges, and emerging opportunities regarding photolytic reaction synthesis are analyzed. This assessment provides insights into the current state and future potential of these reactions in advancing additive manufacturing technologies. Full article

Phosphorus (P) deficiency is a major factor governing peanut (Arachis hypogaea L.) productivity, and the physiological mechanisms by which different genotypes (with contrasting photosynthetic capacities) coordinate carbon assimilation and photoprotection remain elusive. This study elucidated the strategic divergence among different peanut genotypes in their foliar photosystems to perform physiological homeostasis under low-phosphorus (LP) conditions. Based on a peanut mini-core collection, six representative accessions with contrasting photosynthetic capacities were selected and categorized into high- and low-photosynthetic functional groups. We integrated leaf gas exchange, chlorophyll fluorescence, the trans-thylakoid proton gradient (ΔpH), and antioxidant enzyme assays to evaluate their adaptive responses to low-P stress relative to the high-P (HP) control. Our results demonstrated that LP stress induced widespread photosynthetic inhibition across all accessions; this suppression was primarily driven by non-stomatal limitations. Under LP stress, high-Pn accessions exhibited superior cyclic electron flow (CEF) plasticity synergized with highly plastic guaiacol peroxidase (POD) activity, suppressing the leaf-level ROS burst and maintaining a substantial ΔpH for ATP synthesis and PSI stability. Conversely, low-Pn accessions suffered from severe oxidative overload and relied heavily on passive thermal dissipation, characterized by elevated non-photochemical quenching (NPQ) values and restricted CEF engagement. Principal component analysis (PCA) confirmed that while baseline biochemical impairments were universal, the capacity to dynamically modulate this ΔpH-dependent regulatory network—which integrates CEF, cytochrome b6f photosynthetic control, and antenna-level NPQ—served as the decisive determinant underlying genotypic variations in photosystem resilience under P deficiency. This study demonstrated that peanut genotypes deploy divergent, ΔpH-centered strategies to balance light energy distribution under P-limited conditions. These findings provide a novel and plausible mechanistic framework for selecting and breeding P-efficient peanut cultivars in poor soils with enhanced photosystem resilience. Full article

Waterlogging restricts root-zone oxygen availability and can impair seedling growth and leaf quality in mulberry. Root-zone aeration may reduce waterlogging injury, but its effects on root anaerobic metabolism, photosynthesis, oxidative stress, and leaf functional quality have not been well integrated. In this study, Morus alba L. ‘Longsang No. 1’ seedlings were subjected to four treatments: normal moisture without aeration (CK), normal moisture with intermittent root-zone aeration (RA), waterlogging without aeration (WL), and waterlogging with intermittent root-zone aeration (WL+RA). Waterlogging was maintained with a water layer 1–2 cm above the substrate surface, and root-zone aeration was supplied using an air pump and microporous aeration stones for 30 min every 4 h. Root-zone dissolved oxygen, growth traits, root activity, root fermentative indicators, root and leaf oxidative injury, gas exchange, chlorophyll fluorescence, antioxidant enzyme activities, and leaf quality-related traits were measured after 14 d of treatment. Waterlogging decreased root-zone dissolved oxygen from 6.62 to 1.69 mg L⁻¹. It also reduced plant height, total leaf area, shoot and root dry weight, root activity, Pn, Fv/Fm, Y(II), and ETR. In contrast, WL increased ADH and PDC activities, lactate and ethanol contents, MDA, H₂O₂, electrolyte leakage, and NPQ. Leaf 1-DNJ, polysaccharides, total phenolics, total flavonoids, DPPH, ABTS, and FRAP were also reduced under WL. Intermittent aeration increased root-zone dissolved oxygen to 4.64 mg L⁻¹ under waterlogging and partially alleviated many of these changes. WL+RA showed higher growth, root activity, photosynthetic performance, PSII photochemical efficiency, antioxidant enzyme activities, and leaf functional quality than WL. These results indicate that intermittent root-zone aeration was associated with better mulberry seedling performance under waterlogging, together with changes in root-zone oxygen status, fermentation metabolism, photosynthesis, oxidative balance, and leaf quality. Full article

Mulberry leaves are used as functional food materials, but drought can reduce leaf production and physiological stability. This study evaluated whether foliar sodium selenite application could partially alleviate drought injury while increasing total selenium and selected functional-quality indicators in mulberry (Morus alba L.) leaves. Seedlings were assigned to four treatments: normal water supply with the surfactant-containing control spray (CK), normal water supply with sodium selenite application (Se), drought stress with the control spray (D+CK), and drought stress with sodium selenite application (D+Se). Drought reduced plant growth, leaf water status, leaf pigment status, gas exchange, and PSII photochemical performance while increasing oxidative damage and membrane injury. Under drought stress, sodium selenite application partially maintained growth, water status, photosynthetic performance, and antioxidant enzyme activities and was associated with lower oxidative-damage indicators. Drought alone increased several stress-responsive secondary metabolites but reduced biomass, polysaccharides, and soluble protein, indicating a trade-off rather than a uniform improvement in leaf quality. Compared with D+CK, D+Se increased total selenium, several functional compounds, and in vitro antioxidant capacity. Overall, foliar application of 10 μM sodium selenite was associated with partial drought-stress alleviation and higher functional-quality indicators under controlled pot conditions. Further studies are required to optimize the application dose and evaluate selenium speciation, bioaccessibility, intake safety, and field performance. Full article

Ground-level ozone (${\mathrm{O}}_3$) is a secondary photochemical pollutant whose formation under intense Mediterranean solar radiation makes Greece prone to elevated concentrations, with well-documented respiratory and cardiovascular health effects. Forecasting of ozone in Greece has nonetheless remained limited: prior work has been largely statistical, focused on one or two sites in Athens, and restricted to a single horizon, and no study has compared machine learning forecasts across the urban-to-rural gradient of the national monitoring network. This study addresses that gap with, to our knowledge, the first multi-site comparison of machine learning ozone forecasts spanning the full urban-to-rural typology gradient of a Greek monitoring network, introducing a typology × model accuracy cross-matrix that links site character directly to forecasting performance and offers concrete, horizon-specific operational guidance for early warning deployment. We develop a single, reproducible pipeline and compare three model families, Support Vector Regression (SVR), Random Forest (RF) and gradient boosting (GBM), against a naïve persistence baseline, for next-hour and next-day-maximum ${\mathrm{O}}_3$ prediction at eight urban, suburban and rural stations of the National Air Pollution Monitoring Network (2021–2024). All predictors are derived from the ozone series itself (lagged, rolling and cyclical calendar features); models were tuned and evaluated using a strictly chronological 70/15/15 train/validation/test split per station, with hyperparameters selected on the validation partition and the test partition evaluated only once to prevent temporal leakage. At the next-hour horizon, all models outperformed persistence at every site, with the single exception of SVR at the rural THR site; gradient boosting was best or joint-best (test $R^2$ from 0.83 at the heavily titrated central-urban site to 0.94 at a rural site), and a Wilcoxon signed-rank test on paired per-sample errors confirmed that GBM significantly outperformed Random Forest at all seven evaluated stations ($p<0.05$, and $p<0.001$ at six of them). The next-day-maximum task was substantially harder ($R^2$ between 0.41 and 0.79), and the ranking reversed, with SVR being the best model almost everywhere. Crucially, forecast accuracy declined systematically from rural and suburban toward central-urban sites: the same nitric oxide titration that suppresses urban ozone is also associated with degraded predictability. These results, summarised in the typology × model accuracy cross-matrix, indicate that an operational early warning system for Greece should adopt horizon-specific models, gradient boosting for next-hour nowcasting and SVR for day-ahead maxima, with explicitly higher uncertainty in the urban core, and can be deployed on the network’s real-time (IoT) data stream using ozone observations alone. Full article

Stibnite (Sb₂S₃), the predominant antimony-bearing sulfide mineral, represents a major natural source of antimony (Sb) in mining-impacted environments. Although humic acid (HA) is ubiquitous in mine wastes and surface waters, its influence on the oxidative transformation and mobilization of Sb from Sb₂S₃ under photochemical conditions remains poorly understood. Here, the coupled effects of HA, controlled ultraviolet irradiation and pH on Sb₂S₃ weathering and Sb mobilization were systematically investigated through batch dissolution experiments combined with hydroxyl radical (·OH) determination, elemental sulfur (S⁰) analysis and complementary solid-phase characterization. Sb release increased with increasing pH and was further enhanced by HA, particularly under circumneutral and alkaline conditions. Controlled UV irradiation further increased Sb mobilization under the investigated conditions, with a more pronounced effect in HA-containing systems. The enhanced Sb mobilization was accompanied by increased ·OH production and greater S⁰ accumulation, indicating increased oxidative activity during weathering. SEM, EDS and FTIR analyses further revealed progressive surface morphological and compositional changes, whereas XRD showed that the bulk crystalline structure of Sb₂S₃ was largely preserved. XPS revealed the formation of oxidized Sb- and S-containing surface species, providing evidence for progressive surface chemical transformation. These results indicate that HA and controlled photochemical conditions were associated with enhanced Sb mobilization and oxidative transformation at the Sb₂S₃-solution interface, while the overall weathering remained predominantly surface-confined. The findings highlight the importance of considering natural organic matter, photochemical conditions and pH together when evaluating Sb mobility from sulfide minerals in mining-impacted environments. Full article

Three types of meso-substituted manganese(III) porphyrin complexes with phenyl, propyl, and isopropyl substituents were synthesized to examine their photochemical and electrochemical properties. The distortion of the porphyrin rings and redox potentials depended on the substituents. The fluorescence quantum yields of these porphyrins were significantly low, indicating the rapid deactivation of their singlet excited states. Although weak emissions attributed to higher singlet excited states and charge-transfer states were observed, their quantum yields remained low. Redox potential measurements showed the relatively strong photooxidative ability of these porphyrins from a thermodynamic standpoint. However, photosensitized protein oxidation was barely observed. The rapid deactivation of photoexcited states decreases the probability of photochemical reactions including biomolecule oxidation. These porphyrins suppressed the self-oxidation of photo-irradiated 1-benzyl-1,4-dihydronicotinamide and catalyzed the decomposition of hydrogen peroxide. In conclusion, these manganese(III) porphyrin complexes barely showed photooxidation activity toward biomolecules and demonstrated protective action against phototoxic reactions. Full article

Anthropogenic air pollution represents a significant threat to both environmental and human health, with nitrogen oxides (NO_x) playing a substantial role in the formation of photochemical smog, acid rain, eutrophication, and respiratory diseases. In Bangladesh, NO_x emissions primarily originate from combustion sources such as road transportation, power generation, and industrial activities, while natural sources include lightning, wildfires, and soil emissions. Furthermore, ammonia emissions from fertilizers and livestock exacerbate air quality issues in both urban and rural settings. Despite the acknowledgment of vehicular and industrial contributions, comprehensive and systematic assessments of NO₂ trends across the nation remain scarce. This study presents a complementary, side-by-side assessment of ground-based NO₂ measurements from the Department of Environment (DoE) with atmospheric NO₂ retrieved from the Sentinel-5P TROPOMI Level-3 product via Google Earth Engine (GEE). Spatial distribution patterns of both ground-level and atmospheric NO₂ were analyzed using ArcGIS Pro, along with seasonal and interannual trend assessments from 2018 to 2024. Results indicated pronounced spatial and temporal variability in NO₂ concentrations. The highest levels were consistently recorded over Dhaka and surrounding industrial zones, with moderate accumulation in Chattogram. Winter months (December–February) exhibited hazardous concentrations, with a national maximum of 205.21 µg/m³, while monsoon periods recorded the lowest levels overall, as reflected in its seasonal mean (see below). Seasonal averages indicated the highest concentrations in winter (35.03 µg/m³), followed by pre-monsoon (29.16 µg/m³), with monsoon recording the lowest seasonal mean (19.94 µg/m³). Long-term analysis showed the highest national annual mean NO₂ con-centration in 2018 (44.32 µg/m³), decreasing to 14.81 µg/m³ by 2024, with non-monotonic year-to-year fluctuation in the intervening period (2020–2021 data were unavailable). These findings underscore the necessity for stricter emission regulations and targeted mitigation measures. As a policy recommendation, this may include the implementation of NO_x-selective catalytic reduction (SCR) using NH₃ over metal oxide and zeolite catalysts. This study provides evidence-based insights to support cleaner air initiatives and sustainable environmental management strategies in Bangladesh. Full article

Cyanobacteria are essential primary producers in aquatic ecosystems. Silver nanoclusters (Ag NCs) are emerging ultrasmall nanomaterials with broad applications; however, they inevitably enter aquatic environments. This study investigated the nanotoxicity of Ag NCs on model cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942), revealing concentration-dependent growth inhibition with a 72 h half-maximal effective concentration of 1.19 mg L⁻¹. Ag NCs internalized into Syn7942 cells severely impaired the photosynthetic machinery, evidenced by reduced chlorophyll a content and suppressed photochemical reactions, leading to impaired electron transport. This photosynthetic dysfunction resulted in substantial reactive oxygen species generation and lipid peroxidation, as indicated by elevated levels of malondialdehydes. Although the activities of key antioxidant enzymes were enhanced, oxidative damage ultimately overwhelmed the cellular defense capacity. Furthermore, quantitative analysis of silver ions (Ag⁺) release coupled with comparative toxicity assays of Ag⁺ and Ag NCs confirmed that the toxicity originates from the Ag NCs themselves, rather than from the released Ag⁺. Transcriptional level analysis revealed that Ag NCs altered the expression of genes involved in photosynthesis and metal detoxification. Collectively, this study reveals a unique toxicity mechanism for Ag NCs distinct from that for Ag NPs and Ag⁺, highlighting the potential ecological risks posed by ultrasmall nanomaterials. Full article

Soil salinity is a major constraint on global crop productivity, highlighting the importance of strategies to enhance plant stress tolerance. This study investigated whether root-associated fungal endophytes derived from a salt-tolerant quinoa ecotype could establish associations with a salt-sensitive ecotype and confer systemic physiological and molecular stress-mitigation responses. Fungal endophytes—two Alternaria spp. and one Setophoma sp.—were isolated from roots of Pandela (salt-tolerant genotype) and inoculated BO75 (salt-sensitive ecotype) under severe salt stress (400 mM NaCl). Physiological (potential photochemical efficiency, survival), biochemical (malondialdehyde, proline), molecular (expression of ion transporter genes CqSOS1 and CqNHX1), and elemental (Na⁺, K⁺, Cl⁻ distribution by μ-XRF) responses were evaluated. In the salt-sensitive BO75 genotype, endophyte inoculation was associated with improved stress performance, evidenced by reduced oxidative damage (lower MDA), higher proline accumulation, and enhanced photochemical efficiency. Furthermore, the reduced expression of CqSOS1 and CqNHX1 suggests an improved ionic balance in inoculated plants. Conversely, re-inoculating Pandela yielded negligible effects, suggesting that these endophytes primarily benefit genotypes lacking inherent salt tolerance. These findings indicate that transferring fungal endophytes from halophytic ecotypes can significantly mitigate stress in sensitive genotypes, highlighting their potential for enhancing crop resilience in saline environments. Full article

The frequency and magnitude of droughts are increasing concurrently with atmospheric CO₂ concentration, with profound consequences for plant carbon assimilation. However, the interactions and the underlying physiological mechanism are still not fully understood. To fill the knowledge gap, we exposed Chinese fir (Cunninghamia lanceolata) saplings to two CO₂ concentrations (400 and 800 ppm, representing ambient and elevated CO₂) and two soil water regimes (70% and 40% field capacity; well-watered and drought-stressed conditions) in a factorial design. Net photosynthetic rate (A_n), chlorophyll fluorescence, photosynthetic pigments, oxidative stress indicators, and antioxidant enzyme activities were measured four times over a 45-day treatment period. Under well-watered conditions, elevated CO₂ significantly increased A_n by 61.5%. However, drought stress substantially reduced A_n by 75.0% under ambient CO₂ and by 75.6% under elevated CO₂, whereas no statistically significant CO₂-induced increase was detected under drought conditions. Furthermore, drought stress caused marked reductions in stomatal conductance, transpiration, chlorophyll content, and photosystem II (PSII)-related parameters, together with increased malondialdehyde, proline, and antioxidant enzyme activities. Variance partitioning analysis suggested that stomatal regulation (SR), photosynthetic capacity (PC), and stress response (STR) jointly explained 71% of the variation in A_n. Structural equation modeling further suggested that drought stress restricted the photosynthetic benefits of elevated CO₂ primarily through stomatal closure, concurrently associated with stress-related declines in pigment stability and photochemical performance. These findings suggest that the carbon sink potential of Chinese fir plantations under future CO₂-enriched climates may be strongly constrained by water deficits. Full article