While x-ray scattering and broadband dielectric spectroscopy (BDS) experiments are routinely performed in vacuum and under controlled humidity on bulk samples, in situ measurements of thin films in non-aqueous solvent vapor environments introduce additional requirements. Two controlled environmental chambers for performing grazing incidence x-ray scattering and BDS address this critical need for studying thin films in either aqueous or organic atmospheres. Both chambers enable temperature-controlled measurements under ambient conditions, flowing gas or solvent vapor, or partial pressures generated by solvent reservoirs. In situ control of temperature is achieved by attaching to an external temperature controller. To facilitate grazing incidence small- and wide-angle x-ray scattering and x-ray reflectivity, the environmental chamber for grazing incidence x-ray scattering has exit angles of 2θ = 38° and 51° in the horizontal and vertical directions, respectively. Low x-ray attenuation (∼ 10%) is achieved by using Kapton windows, and the chamber is sealed to enable use in evacuated x-ray scattering systems such as the Xenocs Xeuss 2.0. The broadband dielectric spectroscopy environmental chamber measures dipole dynamics and ionic conductivities of materials on interdigitated electrodes. Cord grip feedthroughs eliminate additional capacitance from the sample chamber and make the environmental chamber broadly compatible with electrochemical impedance spectrometers. The utility of these chambers is demonstrated on three polymeric systems with various film thicknesses, morphologies, and solvents.
Understanding the redox transformations of selenium (Se) under varying redox atmospheres is critical for predicting its environmental fate and optimizing Se removal from contaminated wastewater. However, the influence of redox atmospheres, specifically H2 and O2, on Se transformation mechanisms and the structural nature of the resulting Se(0) remains poorly understood. In this study, we investigated the interactions between aqueous selenate (Se(VI)) and Fe(II)-bearing minerals (pyrite, magnetite and mackinawite) under N2, H2 and air atmospheres, employing comprehensive characterizations on both aqueous and solid speciation. Our findings reveal that H2 and air atmospheres could enhance Se removal by pyrite but limit its removal by mackinawite, while magnetite shows no significant atmospheric influence on Se removal. Alongside Se removal, sorbed Se(VI) was transformed into distinct elemental Se depending on the mineral: trigonal γ-Se nanoneedles on magnetite, monoclinic β-Se on mackinawite, and nanosized amorphous Se(0) on pyrite. Moreover, H2 significantly lowered the solution redox potential, favoring the reduction of sorbed Se(VI) to Se(0) or FeSex. Overall, this work provides valuable insights for optimizing Se remediation and recovery strategies in Se-contaminated wastewater and improving understanding of Se behavior in diverse geochemical systems, including nuclear waste disposal repositories.
Aerobic exercise with eicosapentaenoic acid (EPA) may enhance cognition via cerebrovascular pathways. We tested whether mild hyperbaric oxygen (HBO; 1.41 atmospheres absolute [ATA], approximately 30% O2) adds to gains in cognitive processing capacity (throughput) versus normobaric normoxia (1.0 ATA, approximately 21% [20.9%] O2). Healthy young adults (n = 16) performed cycling exercise at 60-70% VO2peak for 60 min, twice weekly, for 4 weeks per environment with a 1-week washout; EPA (2170 mg·day-1) was taken during each 4-week training phase (total 8 weeks) and was paused during the washout. An EPA-only control (n = 8) was included for supplementary analysis. The primary outcome was throughput (correct·min-1; T1-T4); secondary outcomes were interference indices (I1: stroop interference, I2: reverse-stroop interference). Effects were estimated using linear mixed models [environment, time, environment × time; AR(1), REML] and Hedges' gav; accuracy used generalized estimating equations. Throughput improved mainly with time (T1-T2 p < 0.001; T4 p = 0.017; T3 p = 0.055), with no environment or interaction effects. I1/I2 showed no significant change, and one task exhibited an accuracy ceiling. Under safe, feasible conditions (≤1.41 ATA), aerobic exercise improved processing capacity (throughput) independently of environmental oxygenation level. The absence of detectable additive effects should be interpreted cautiously under conservative settings.
Understanding the dynamic evolution of Cu species under varying environmental conditions is critical for addressing challenges related to the activity and the stability of copper-based catalysts in thermo-, photo-, and electrocatalysis. However, metal-metal interactions between dual single atoms and their effects on Cu evolution after exposure to different environmental molecules remain underexplored. Herein, we synthesized bimetallic Cu-Y/Beta catalysts with dual single-atom Cu and Y sites and monometallic Cu-Beta catalysts with isolated Cu sites in dealuminated Beta zeolites. By varying Cu and Y compositions, diatomic interactions were studied under H2 and ethanol atmospheres. With 6 wt% Y loading, approximately 0.4 wt% of Cu species in Cu-Y/Beta remained partially oxidized as Cu(I) after reduction in pure H2 at 350 °C, in contrast to the full transition to metallic Cu observed in Cu-Beta. Combining X-ray absorption spectroscopy with kinetic studies revealed that metallic Cu became the predominant species after reduction with H2 as Cu loading increased from 0.4 to 1.7 wt%, quadrupling the initial ethanol dehydrogenation rate and demonstrating the dominant role of Cu(0) sites. Scanning transmission electron microscopy and density functional theory simulations indicated spatial proximity between dual single-atom Cu and Y sites and elucidated Cu speciation controlled by diatomic interactions.
Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant organic contaminants whose multi-ring aromatic structures contribute to their persistence and ecological toxicity. In this work, cocoa pod husk (CPH), a major agricultural residue, was converted into biochar through thermochemical treatment to investigate how pyrolysis atmosphere regulates the generation and retention of PAHs. Biochar samples were produced across 300-900 °C under CO2 or N2 atmospheres, yielding a set of cocoa pod husk biochar (CPHBC) with distinct chemical characteristics. High-ring PAHs, particularly dibenzo[a,h]anthracene (DA) and indeno[1,2,3-cd]pyrene (IP), dominated the aromatic profiles. The CO2-pyrolyzed material at 700 °C exhibited the greatest PAH burden (2478 ± 228 ng g⁻1), whereas high-temperature treatment under N2 (900 °C) resulted in substantial suppression of PAH accumulation (104 ± 22 ng g⁻1). Ecotoxicological testing with zebrafish (Danio rerio) embryos from 0 to 4 dpf revealed no detectable alterations in assessed developmental endpoints, locomotor behavior, or oxidative stress biomarkers under short-term laboratory exposure, indicating that the CPHBC did not induce observable acute toxicity within the tested conditions. Collectively, the results demonstrate that judicious control of pyrolysis atmosphere can effectively limit PAH formation in CPH-derived biochar, reducing potential ecological and food-chain hazards while supporting the sustainable reuse of biomass within a low-carbon circular bioeconomy.
This study presents the first year-long observations (January 2021-June 2022) of 17 non-methane hydrocarbons (NMHCs) at a high-altitude rural site in the Himalayas (Munsyari: 2200 m a.m.s.l.), a tourist destination influenced by nearby emission sources. Total NMHCs exhibited seasonal variability, with the lowest levels in winter and summer- monsoon (159.5-174.5 ppbC) and the highest levels in spring and autumn (174.5-197.8 ppbC). Aromatic hydrocarbons dominated the NMHC composition throughout the year, contributing about 85-89% of the total NMHCs. This seasonal variability suggests the combined influence of local emissions, boundary layer dynamics, temperature-driven emissions, upslope winds, and biomass burning processes. Further, hydrocarbon ratios highlighted the role of hydroxyl (OH)-driven oxidation processes in the removal of NMHCs. Correlation analysis and ternary plot also indicate contributions from local emission sources such as liquefied petroleum gas (LPG), diesel fuel emissions, and possible solvent use. In addition, the relatively higher levels (4-6 times) compared with other high-altitude sites (e.g., Mt. Abu and Nainital), together with variability-lifetime analysis, suggest the dominance of local sources at this site. However, levels were 3-14 times lower than those at Kathmandu and Indo-Gangetic Plain (IGP) sites. Reactivity-based analyses showed that p-xylene, m-xylene, isoprene, and toluene were major contributors to propylene-equivalent concentration (PEIC), ozone formation potential (OFP), and secondary organic aerosol formation potential (SOAFP). Health risk assessment indicated that non-cancer hazard ratios remained below the threshold, whereas lifetime cancer risk exceeded the USEPA limit, with benzene being the dominant contributor. Overall, these findings provide new insights into the distribution, sources, and atmospheric implications of NMHCs at a high-altitude rural site in the Himalayan region.
Airborne microplastics (AMPs) have drawn increasing scientific attention in recent years owing to their long-range transport potential and demonstrated risks to the environment and human health. This investigation systematically examines AMP characteristics in Macao, focusing on their: (1) spatiotemporal distribution patterns, (2) morphological and chemical profiles, (3) key influencing factors, and (4) associated ecological risks. Notably, a shape-stratified analysis was implemented, differentiating fibrous from non-fibrous AMP fractions, followed by comparative analysis against unfiltered shape aggregates. Substantial spatial variability in AMP deposition fluxes across Macao was revealed, with values ranging from 114 ± 77 to 1164 ± 651 MP/m2/day (mean: 517 ± 457 MP/m2/day). Population density emerged as the strongest predictor of spatial AMP variability (p < 0.01), exhibiting exponential relationships with deposition fluxes. Meteorological parameters displayed distinct shape-dependent influence patterns across monitoring locations. A positive correlation emerged between AMP abundances and inhalable particulate matter (PM10-2.5) concentrations (r > 0.71, p < 0.05), suggesting potential co-production and co-transport mechanisms. Maximum wind velocity was identified as critical drivers of short-term AMP flux variations, potentially through aerosolization of terrestrial plastic reservoirs. The backward trajectory results emphasized the influence of wind and air mass sources. Finally, the potential ecological risk was used as an example to illustrate the limitations of existing risk assessment models for AMP. This work establishes microplastic morphology as a critical mediator in atmospheric transport dynamics, quantitatively demonstrates the dual anthropogenic-meteorological control of AMP distributions, and provides new insights into the factors affecting the spatiotemporal variation of the abundance.
The size-dependent gas-particle partitioning of transformation products (TPs) from organophosphate esters (OPEs) and the transform potential for OPEs to TPs in ambient atmosphere remain under-investigated. To fill this knowledge gap, we analyzed gaseous and size-fractionated particle samples collected from Beijing, Shanghai, and Guangzhou in China under different meteorological conditions. The concentrations of OPEs were comparable to those in other major cities worldwide, but the levels of TPs were lower than those in these cities. The Li-Ma-Yang model predicted well the size-fractionated gas-particle partition coefficients (Kp) of OPEs and TPs with log KOA > 9.1. Multiple linear regression model incorporating relative humidity narrowed the gap between predicted and observed Kp of OPEs with log KOA < 9.1, but still underestimated the Kp values. Hence, humidity-dependent water film adsorption and transformation of these OPEs should be included in future gas-particle partition modeling, especially in fine particles. Size distributions in concentration ratios of nine pairs of OPE to TP were not unified. Temperature exhibited negative effects on gas-particle partitioning of TPs, and inhibited the transformation of tris(2-chloropropyl) phosphate (TCIPP) to bis(1-chloro-2-propyl) phosphate (BCIPP) and triphenyl phosphate (TPhP) to 4-hydroxyphenyl diphenyl phosphate (4-OH-DPHP) in the particulate phase. Gaseous TPs contributed more to the human inhalation health risks of OPEs than particle-bound TPs. These findings are significant for comprehending the fate of atmospheric TPs in urban environment. ENVIRONMENTAL IMPLICATION: Transformation products (TPs) of organophosphate esters (OPEs) exhibit comparable or even enhanced toxicity relative to OPEs, but their atmospheric behavior remains incompletely understood. In the present study, gaseous and size-fractionated particulate samples were collected in Beijing, Shanghai, and Guangzhou to explore the gas-particle partitioning behavior of TPs and their transformation potential from OPEs. Results indicated that relative humidity influenced the gas-particle partitioning behavior of compounds with log KOA < 9.1, especially in fine particles. The transformation potentials of individual OPE to its TP were size-dependent. These findings are significant to comprehending the fates of OPEs and TPs in urban atmosphere.
Exposure to air pollution containing particulates (PM) and gas-phase volatile organic compounds (VOCs), is a leading cause of human morbidity and mortality globally. Devising effective protective public health strategies requires an assessment of the relative contribution of PM and VOCs to the health effects of air pollution exposure. To enable studies of VOCs isolated from mixed atmospheres, we developed a positive air pressure exposure system that permits the subject to breathe unimpeded by the pressure drop imposed by filtering respirators. This system uses pumps to draw air through respirator filters and delivers it to a modified positive pressure respirator at a flow rate that exceeds the ventilatory requirements of the wearer, while preventing infiltration of the surrounding atmosphere. Tests showed negligible leaks (<5% flow reduction) and minimal VOC losses (95% recovery) to the system. When tested using an atmosphere containing woodsmoke, PM filters showed effective exclusion of particulates but minimal losses of VOCs, while activated carbon based cartridges effectively removed gaseous compounds and PM. A team member exercising moderately in a woodsmoke atmosphere for 2-hours reported no perveivable odors and experienced no discomfort during an exposure using charcoal filter cartridges. We report the development and validation of a novel human exposure system that allows selective exposure to the gaseous fraction of a mixed atmosphere. This system allows for moderate to vigorous exercise of the study subject and can be used in place of an exposure chamber, making it compatible with clinical and field studies. Developing strategies to protect the public from exposure to air pollution requires studying the relative toxicity of gaseous and particle mixtures.Studies can be conducted in human volunteers wearing tight-fitting respirators that filter out gases and/or particles.However, respirators require considerable effort to breathe against, and this negative pressure limits the exertion that the wearer can perform.We therefore developed and tested an exposure system that uses external pumps to deliver filtered air under positive pressure to the breathing zone of a volunteer undergoing moderate exercise.We show that the system can be used to effectively filter particles, allowing gaseous compounds in the exposure atmosphere to pass through, while the study volunteer exercises comfortably at moderately strenuous levels.This novel exposure system is compatible with standard respirator filters and can be used for clinical and field studies.
Achieving high-efficiency perovskite solar cells (PSCs) typically necessitates postdeposition annealing under stringent environmental controls, such as low relative humidity or inert atmospheres. These demanding conditions significantly increase the complexity and cost of device fabrication. Therefore, developing an annealing strategy for obtaining high-quality, phase-pure α-FAPbI3 perovskite in ambient or high-humidity environments is critically important. Here, we demonstrate that coevaporated FAPbI3 perovskite active layers annealed in a saturated-humid environment exhibit pure α-phase and thus markedly superior device performance compared to those annealed in normal air or an inert atmosphere. The resulting preferred crystal orientation, superior carrier transport properties, and retarded charge carrier recombination collectively enable an excellent power conversion efficiency (PCE) of up to 21.3% in vacuum-deposited inverted PSCs. Additionally, these devices also deliver excellent performance under indoor environmental light-harvesting, achieving PCEs of 34.9% and 36.7% under 1000 lx illumination from 6500 K and 3000 K fluorescent light sources, respectively.
Hexafluoropropylene oxide dimer acid (GenX), a perfluorooctanoic acid substitute, poses environmental risks due to its persistence and toxicity. Effective defluorination methods are crucial, especially in clarifying reactive species' roles in carbon-skeleton disruption versus C-F bond cleavage. We present a novel UV/Fe(NO3)3 system that integrates ligand-to-metal charge transfer (LMCT), reactive nitrogen species (RNS), and singlet oxygen (1O2) to achieve 90% GenX degradation in 1 h and 99% defluorination in 6 h. Mechanistic studies under controlled atmospheres reveal a hierarchical pathway: Fe3+-triggered LMCT initiates C-C bond disruption, decarboxylation, and ether-oxygen bond cleavage, while nitrate-photolysis-derived RNS accelerates this process via electron transfer (ET). Fe2+-mediated conversion of O2 to 1O2 drives C-F bond scission, revealing an oxygen-dependent cascade defluorination involving Fe3+/Fe2+ redox cycling and RNS. Oxygen availability raises defluorination from 8 to 99%. Density functional theory calculations confirm that the Fe2+ activation of triplet O2 to 1O2 lowers the defluorination barrier by 118.8 kcal/mol. This approach works across diverse water matrices, achieving >88% defluorination of eight per-/polyfluoroalkyl substances (PFAS) within 12 h and remains robust in treating fluorochemical effluents. Using acidic iron-containing pickling wastewater as an in situ reagent enables >90% GenX defluorination, offering a closed-loop, additive-free, scalable solution for sustainable PFAS remediation.
New particle formation (NPF) substantially affects air pollution and climate change. However, as an NPF hotspot, the mechanisms and impacts of NPF across broad spatial and temporal scales over China remain poorly understood, largely owing to the lack of critical NPF processes in atmospheric models. This study developed a comprehensive model that integrates 12 NPF mechanisms, including recent insights on various iodine-oxoacid-driven pathways and cluster-dynamics-based rate calculations. The updated model reduces model-observation discrepancies from around or over an order of magnitude to within ±30% across different sites and seasons. Simulations revealed that NPF over mainland China is driven primarily by sulfuric acid (H2SO4), dimethylamine (DMA), and iodic acid (HIO3). Importantly, H2SO4-DMA nucleation is not only the dominant mechanism in urban atmospheres, but also a major contributor in agricultural and forested regions. Differently, the HIO3-(H2SO4)-DMA mechanism contributes substantially in southeastern coastal areas, while iodine-oxoacid-H2SO4 pathways dominate in marine regions. High H2SO4 levels are identified as the main driver of eastern China's NPF hotspots, with temperature governing seasonal variations. Correspondingly, NPF contributes 10%-35% of cloud condensation nuclei (at 0.5% supersaturation) in the lower troposphere. Our models and findings support comprehensive understanding of NPF over China, and are also highly valuable for studying NPF in other regions with diverse emission sources and land cover types, and thereby contributing to accurate assessment of the environmental and climatic effects of aerosols.
The presence of antibiotics in aquaculture wastewater poses environmental and public-health risks by disrupting aquatic ecosystems and promoting the spread of antibiotic-resistant bacteria. This study evaluates pine-bark biochars activated under different atmospheres for the removal of tetracycline from real aquaculture wastewater and examines their combined use with peroxymonosulfate as an oxidant. The biochars were produced by pyrolysis and activated using carbon dioxide or humid argon. Carbon-dioxide activation generated a larger surface area and a more developed porous structure than humid-argon activation, which resulted in higher adsorption performance. Batch experiments achieved 80-100% tetracycline removal in real aquaculture wastewater containing competing ions and dissolved organic matter. Adsorption kinetics followed the pseudo-second-order model, indicating that chemisorption governed the process, while intraparticle diffusion contributed but was not the controlling step. The solution pH strongly influenced adsorption, with maximum removal under alkaline conditions. Results suggest that aromatic ring interactions, hydrogen bonding and surface complexation were predominant adsorption mechanisms. Combining biochar with peroxymonosulfate enhanced tetracycline removal through a synergistic effect, reaching up to 99% with very low oxidant dosages. These findings highlight pine-bark biochar as a promising and sustainable metal-free material for treating contaminants of emerging concern in aquaculture wastewater.
Airborne microorganisms play a significant role in atmospheric processes and public health, yet their variations over high-altitude regions are underexplored. To investigate the meteorological influence and role of transport patterns on airborne microorganisms, we analyzed DNA sequencing of bacterial population collected from ambient atmosphere during 2022-2023 over Darjeeling (27.03°N, 88.26°E; 2,200 m amsl), an Eastern Himalayan hilltop site, and categorized as winter (dry: cold, stable), pre-monsoon (semi-dry: warm, transitional), monsoon (wet: humid, rainy), and post-monsoon (semi-wet: cooler, cloudy) seasons. Back-trajectory analysis showed air masses from the western Indo-Gangetic Plain during pre-monsoon and from the Bay of Bengal during monsoon, while winter and post-monsoon air masses were predominantly regional hilly winds. Significant seasonal variability in airborne bacterial populations was noticed over the Eastern Himalayas, with highest abundance and diversity in pre-monsoon (cell count = 5.8 ± 1.9 × 105 m-3, operational taxonomic units = 597 ± 343, genera = 188 ± 76, Shannon = 4.1 ± 1.0) due to continental wind transport and particulate matter influx. About one-fourth of airborne bacterial genera were persistent in all seasons, representing background Himalayan hilltop airborne bacterial population. Unique season-specific genera are prominent in pre-monsoon (15%), followed by post-monsoon (7%), monsoon (6%), and winter (4%), indicating significant enrichment of airborne bacteria due to the influence of wind. Positive correlations with wind speed (r = 0.57, P < 0.05), temperature (r = 0.50, P < 0.05), and PM2.5 (r = 0.84, P < 0.001) indicate the role of meteorological parameters in shaping airborne bacterial population. Human pathogens like Acinetobacter, Staphylococcus, and Corynebacterium, responsible for gastroenteritis and respiratory, skin, and urinary tract infections, highlight potential health risks and the importance of integrating atmospheric biological data and meteorological modeling into public health strategies over Eastern Himalayan region.IMPORTANCEAirborne microorganisms play an important role in atmospheric processes, ecosystem functioning, and human health. However, their dynamics in high-altitude regions are poorly characterized. The present study provides the first comprehensive seasonal assessment of Eastern Himalayan airborne bacterial diversity and abundance, revealing strong meteorological control, particularly wind patterns and particulate matter, on airborne bacterial loading and community composition. Identification of opportunistic pathogenic bacterial genera across all seasons raises concerns about potential health impacts, especially in regions where population density and tourism are increasing. Our findings also highlight continental transport of airborne bacteria from distant source regions like the Indo-Gangetic Plain, suggesting airborne bacterial influx. By integrating atmospheric biological data with air-mass back-trajectory simulation, the present study highlights valuable insights into how wind influences Himalayan airborne bacterial community. These insights are essential for developing airborne bacterial forecasting tools and public health strategies in vulnerable hilltop atmospheres that undergo rapid environmental change.
Ubiquitous airborne microplastics (AMPs) pose significant health risks to densely populated urban residents. This study characterized the spatiotemporal dynamics and physicochemical properties of AMPs in Hangzhou, China. A continuous one-year active (pumped) sampling campaign was conducted at human breathing height using a two-stage inlet (TSP and PM10) across four functional zones (residential, industrial, shopping center, and roadside). The mean TSP AMPs abundance was 4.43 ± 3.11 particles·m-3 (median: 4.61 ± 2.72 particles·m-3; range: 0.22-9.48 particles·m-3). PM10 accounted for >72% of total AMPs, and ∼89% of particles were <100 μm in length (10-1066 μm; mean: 57.27 ± 1.29 μm; median: 39.00 ± 35.48 μm). Morphologically, fragments dominated (>93%), whereas fibers were mainly observed among larger particles (>700 μm). LDIR spectroscopy identified 28 material types, with a profile dominated by Polyamide (45.6%), Rubber (10.2%), and Acrylonitrile Butadiene Styrene (9.4%), consistent with contributions from textile- and traffic-related urban activities. Rank-based factorial analysis (Scheirer-Ray-Hare) indicated a strong seasonal effect for both TSP and PM10 (p < 0.001), and Dunn-Holm post-hoc tests showed significantly lower abundances in summer than in spring, autumn, and winter (P_Holm <0.001). Spatial contrasts were weaker: the site effect was marginal for TSP (p = 0.0525) but significant for PM10 (p = 0.0452), with a significant difference between the residential and roadside sites (P_Holm = 0.028). These findings provide essential insights into the characteristics, dynamics, and environmental impacts of AMPs in urban atmospheres, highlight the health risks posed by traffic-related, inhalable microplastics, and suggest that seasonal meteorology is a major driver of the observed summer minima in subtropical monsoon climates.
New particle formation (NPF) is a major global aerosol source, impacting air quality, public health, and Earth's radiative balance. NPF mechanisms have been clarified in megacities and in the remote marine environment, yet little is known about the compounds and molecular steps driving NPF in coastal urban atmospheres. The role of iodic acid, a well-known marine precursor, remains unclear in coastal regions. Here, we report 1 year, molecular-level measurements of nucleating clusters in Dalian, a coastal city in northern China. We provide direct observational evidence that iodic acid (HIO3), together with sulfuric acid (H2SO4) and amines, contributes to coastal NPF under real atmospheric conditions. Iodine-containing clusters account for 3.3%, 17.7%, 15.5%, and 4.5% of the dimers in spring, summer, autumn, and winter, on average, respectively, and can reach up to 50%. Iodic acid also significantly improves the early growth and survival of newly formed particles, with the survival probability of particles being increased by up to 8-fold. Our ambient observational results highlight the crucial role of iodic acid in airborne aerosol production (secondary aerosol formation) within mixed marine-continental atmospheres.
Background/Objectives: As bacteriophage-based strategies to control bacterial pathogens continue to gain momentum, phage therapy is increasingly being explored across various fields. In the poultry industry, efforts to minimize the public health impact of Salmonella have spurred growing interest in phage applications, particularly as prophylactic and disinfecting agents. Although the disinfecting potential of bacteriophages has been recognized, in-depth studies examining their efficacy under varying environmental conditions remain limited. This study focused on evaluating the effectiveness of bacteriophages as disinfecting agents against biofilm-forming Salmonella Infantis under different environments. Methods: A comprehensive screening of biofilm-producing strains was conducted using Congo Red Agar and 96-well plate assays. Two strains with distinct biofilm-forming capacities were selected for further analysis under different environmental conditions: aerobic and microaerobic atmospheres at both 25 °C and 37 °C. The resulting biofilms were then treated with four phage preparations: three individual phages and one phage cocktail. Biofilm reduction was assessed by measuring optical density and CFU/well. Additionally, scanning electron microscopy was used to visualize both untreated and phage-treated biofilms. Results: The results demonstrated that all S. Infantis strains were capable of forming biofilms (21/21). All three phage candidates exhibited biofilm-disrupting activity and were able to lyse biofilm-embedded Salmonella cells. Notably, the lytic efficacy of the phages varied depending on environmental conditions, highlighting the importance of thorough phage characterization prior to application. Conclusions: These findings underscore that the effectiveness of bacteriophages as surface disinfectants can be significantly compromised if inappropriate phages are used, especially in the presence of biofilms.
A new strategy for preparing highly dispersed, richer oxygen vacancies Ni/ZrO2 catalysts derived from UiO-66-NH2 is reported via pyrolysis-calcination removal of the ligands under N2, CO2, and Air atmospheres followed by loading Ni with 5 wt.% via wet impregnation method. Subsequently, the low-temperature dry reforming of methane (DRM) reaction over the obtained Ni/ZrO2 catalysts was preliminarily investigated. The results indicated that the Ni/ZrO2C catalyst, obtained by two-step pyrolysis in CO2, contained smaller Ni particles with a size of only 5-7 nm and possessed a hierarchical porous structure, as well as richer oxygen vacancies and basic active sites compared to the other two catalysts. Its catalytic activity in the DRM reaction presented the highest initial conversion of CH4 (35 %) and CO2 (26 %) at 600 °C, which was 5 % higher than that of the Ni/ZrO2N and Ni/ZrO2O catalysts obtained by two-step pyrolysis under an N2 atmosphere and one-step pyrolysis under an air atmosphere, respectively. Meanwhile, an in-situ DRIFTS experiment revealed that Ni/ZrO2C could enhance the adsorption and activation of CO2 by promoting the formation of formate as an intermediate of CO hydrogenation and reverse water-gas shift (RWGS) reactions, which in turn facilitates the decomposition of CH4.
Declining nitrogen oxide (NOx = NO + NO2) emissions have transformed oxidation pathways in urban atmospheres, with implications for air quality. Organic peroxy radicals (RO2), key intermediates in volatile organic compound oxidation, typically react with NO to form ozone (O3). Under lower-NO conditions, alternative RO2 fates, including isomerization forming highly oxidized organic molecules (HOMs), can enhance secondary organic aerosol (SOA) production. We combine aircraft observations over four major North American cities with geostationary satellite data to characterize isoprene-derived RO2 fate across urban environments. We infer RO2 bimolecular lifetimes (τbi) as a proxy for isomerization potential, finding longer τbi (17 ± 11 seconds) in New York, Chicago, and Toronto compared to Los Angeles (7 ± 6 seconds). Satellite measurements reveal that long τbi is widespread across urban North America, suggesting that declining NOx is likely to lead to greater HOM formation in urban regions. These findings indicate that atmospheric models omitting RO2 isomerization chemistry may incorrectly simulate organic oxidation and the subsequent oxidation state of volatile organic compounds and SOA.
Cobalt-based catalysts exhibit high activity for nitrous oxide (N2O) decomposition, but their sensitivity to the nitrogen oxides (NOx) in exhausts strongly hinders practical application. In this study, a gadolinium‑cobalt (GdCo) oxide catalyst supported on MOR (Mordenite) zeolite was developed. Under rigorous conditions containing 7 vol% N2O, 1000 ppm NO, 5 vol% H2O, 10 vol% O2, and a gas hourly space velocity (GHSV) of 10,000 h-1, the 15Gd1Co10Ox/MOR catalyst achieved 100% N2O conversion at 350 °C, exhibiting excellent low-temperature activity and outstanding NO tolerance. The incorporation of Gd modulates the electronic structure of cobalt via Gd-O-Co bridges, which facilitates NO bond cleavage and activates lattice oxygen, thereby establishing a low-energy oxygen recombination (O-OL) pathway that effectively overcomes the rate-limiting O2 desorption step. Furthermore, the Brønsted acid sites on the MOR support play a key role in enhancing NO resistance by selectively adsorbing NO molecules, thereby effectively protecting the Co3+ active sites essential for N2O decomposition. Meanwhile, the active oxygen species (O⁎) derived from N2O dissociation react with adsorbed NO to form NO2, which not only maintains the catalytic cycle but also lays a foundation for subsequent selective catalytic reduction (SCR) processes. This synergistic mechanism between GdCo oxide and the MOR zeolite enables highly efficient and stable N2O decomposition in NO-containing atmospheres, providing a promising strategy for designing industrial catalysts for ultra-low emissions from nitric/adipic acid production and other related chemical processes.