Half-sandwich ruthenium complexes with acylhydrazone ligands: synthesis and catalytic activity in the N-alkylation of hydrazides.

Novel half-sandwich ruthenium complexes termed [(p-cymene)RuClL] were synthesized by chelating arylhydrazone ligands with [(p-cymene)RuCl2]2 and were then fully characterized using different spectroscopic and analytical techniques. The crystal structure of complex 4 indicated that the hydrazone ligands bonded to the ruthenium ion in a bidentate manner through the imine nitrogen and imidazolate oxygen, exhibiting a pseudo-octahedral geometry centered by the ruthenium atom. The as-fabricated air and moisture stable half-sandwich ruthenium complexes demonstrated excellent catalytic activity towards the N-alkylation of hydrazides under mild conditions. Under the catalysis of ruthenium complexes, acyl hydrazides were reacted with different types of alcohols in a one-pot reaction, resulting in N-alkylation hydrazides with different substituents. This catalyst exhibited characteristics such as high catalytic efficiency, broad substrate scope, and mild reaction conditions, indicating that it has great potential for industrial applications.

Incorporating the benefits of vegetative filter strips into risk assessment and risk management of pesticides.

The pesticide registration process in North America, including the USA and Canada, involves conducting a risk assessment based on relatively conservative modeling to predict pesticide concentrations in receiving waterbodies. The modeling framework does not consider some commonly adopted best management practices that can reduce the amount of pesticide that may reach a waterbody, such as vegetative filter strips (VFS). Currently, VFS are being used by growers as an effective way to reduce off-site movement of pesticides, and they are being required or recommended on pesticide labels as a mitigation measure. Given the regulatory need, a pair of multistakeholder workshops were held in Raleigh, North Carolina, to discuss how to incorporate VFS into pesticide risk assessment and risk management procedures within the North American regulatory framework. Because the risk assessment process depends heavily on modeling, one key question was how to quantitatively incorporate VFS into the existing modeling approach. Key outcomes from the workshops include the following: VFS have proven effective in reducing pesticide runoff to surface waterbodies when properly located, designed, implemented, and maintained; Vegetative Filter Strip Modeling System (VFSMOD), a science-based and widely validated mechanistic model, is suitable for further vetting as a quantitative simulation approach to pesticide mitigation with VFS in current regulatory settings; and VFSMOD parametrization rules need to be developed for the North American aquatic exposure assessment. Integr Environ Assess Manag 2024;20:454-464. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Cationic N,S-chelate half-sandwich iridium complexes: synthesis, characterization, anticancer and antiplasmodial activity.

A series of pyrazole-based ligands and their corresponding cationic N,S-chelate half-sandwich iridium complexes were successfully synthesized. All iridium complexes exhibited good anticancer activity against the MCF-7 and MDA-MB-231 human breast cancer cells. The cytotoxic activity of unsubstituted iridium complex 1 is greater than that of cisplatin against MCF-7 cells. In addition, the cationic half-sandwich iridium complexes are also efficient in antiplasmodial study and complex 1 displayed the best activity as its IC50 was observed to be approximately 0.11 µM against the CQS-NF54 strain. These iridium complexes generally exhibited enhanced activity against the CQS-NF54 strain in comparison with that against the CQR-K1 strain. An "IC50 speed assay" investigation against the CQS-NF54 strain indicated complexes 1-3 to be fast-acting complexes that reach their lowest IC50 values within 16 hours. All complexes were fully characterized by IR spectroscopy, NMR spectroscopy, and elemental analysis, and the structure of the iridium complex was confirmed by single-crystal X-ray diffraction.

Review on the conceptual framework of teacher resilience.

Resilience is the ability to bounce back from setbacks and adapt to new circumstances. Resilient teachers can handle these issues. In this case, it's proposed to interpret the recent decade's resilience research on teachers. Provide a conceptual framework for teacher resilience factors. The Scopus database was used to collect articles. The titles and abstracts of articles were read one by one. As a result, 22 articles were included in the data analysis. The country where the data were collected, the aims of the study, the education level which the participants working, the sample size, the scale used, and the variables included in the study are marked in the full text. Most studies were effect determination, correlation, or exploratory. Initially, age and gender inequalities among instructors were examined. Postgraduate instructors are more resilient than undergraduates. Psychological factors, workplace variables, and teacher competency and attributes are used to study teacher resilience. Teachers' resilience negatively impacts depression, stress, anxiety, well-being, and mood. Quality of life and well-being are positively connected. Job crafting, work engagement, and working environment are favorably connected, whereas job burnout and turnover intention are adversely correlated. Resilience was positively connected with emotion regulation, empathy, others' emotion evaluation, teacher competence, teacher self-efficacy, and self-esteem in teachers. Anger, anxiety, mindfulness, pleasure, social support, fear, and training affect teachers' resilience. Teachers' resilience affects stress, depersonalization, personal accomplishment, emotional exhaustion, children's resilience, job engagement, happiness, well-being, self-care, and success.

Half-sandwich iridium complexes with hydrazone ligands: preparation, structure, and catalytic synthesis of cyanosilylethers under air.

A series of hydrazone-based N,O-chelate half-sandwich iridium complexes were synthesized through a facile route with good yields. These air- and moisture-stable iridium complexes exhibited excellent catalytic activity in the cyanosilylether synthesis under mild reaction conditions. Under the catalysis of iridium, various cyanosilylethers with different substituents were obtained through a one-pot reaction of trimethylsilyl cyanide (TMSCN) with carbonyl substrates, with good to excellent yields. The excellent catalytic efficiency, wide substrate range, and mild reaction conditions made this type of iridium catalyst have the potential for industrial applications. All the half-sandwich iridium complexes were well characterized by IR, NMR, and EA analyses. The molecular structure of iridium complex 1 was confirmed by single-crystal X-ray analysis.

Immunological and prognostic analysis of PSENEN in low-grade gliomas: An immune infiltration-related prognostic biomarker.

Metformin is widely used in the treatment of type 2 diabetes (T2D) and plays a role in antitumor and antiobesity processes. A recent study identified its direct molecular target, PEN2 (PSENEN). PSENEN is the minimal subunit of the multiprotein complex γ-secretase, which promotes the differentiation of oligodendrocyte progenitors into astrocytes in the central nervous system. This study was mainly based on gene expression data and clinical data from the TCGA and CGGA databases. Analysis of differential expression of PSENEN between tissues from 31 cancers and paracancerous tissues revealed that it had high expression levels in most cancers except 2 cancers. Using univariate Cox regression analysis and Kaplan-Meier survival analysis, a high expression level of PSENEN was shown to be a risk factor in low-grade gliomas (LGG). Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analyses indicated that PSENEN is widely involved in immune-related signaling pathways in LGG. PSENEN expression level was significantly associated with TMB, MSI, tumor stemness index, and the expression levels of immunomodulatory genes in LGG. Finally, immune infiltration analysis revealed that PSENEN level was associated with the presence of various immune infiltrating cells, among which PSENEN was strongly associated with the presence of M2 macrophages and played a synergistic pro-cancer role. In conclusion, PSENEN may partially influence prognosis by modulating immune infiltration in patients with LGG, and PSENEN may be a candidate prognostic biomarker for determining prognosis associated with immune infiltration in LGG.

Effects of Multimedia Assisted Song Integrated Teaching on College Students' English Learning Interests and Learning Outcomes.

In the process of globalization, the English language not only represents British and American culture, but it has also gradually become a language used all over the world, and it has become essential for many people to learn it as a second language. Education is the century business of a nation. At the same time, to meet the needs of E generation, I generation, and touch-screen generation students, teachers are increasingly undertaking multimedia-integrated curriculum design and instruction. Teachers are no longer knowledge providers, but they are expected to provide students with a personalized learning model and guide and support them in a timely manner. This study included a sample of business students from Guilin University of technology. A total of 216 students participated in a 16-week (3 h per week, a total of 48 h) course of experimental teaching. The research results showed that 1. multimedia assisted, song integrated English teaching affected learning interest, 2. That multimedia assisted, song integrated English teaching affected learning outcomes, and 3. That learning interest had significantly positive effects on learning outcome. Based on these results, this study contributes to improving college students' English listening, speaking, reading, and writing skills via multimedia teaching, which also facilitated their interest and ability to achieve the learning outcomes.

A data-augmentation approach to deriving long-term surface SO2 across Northern China: Implications for interpretable machine learning.

Until recently, Northern China was one of the most SO2 polluted regions in the world. The lack of long-term and spatially resolved surface SO2 data hinders retrospective evaluation of relevant environmental policies and human health effects. This study aims to derive the spatiotemporal distribution of surface SO2 across Northern China during 2005-2019. As "concept drift" causes substantial estimation bias in back-extrapolation, we propose a new approach named the robust back-extrapolation via data augmentation approach (RBE-DA) to model the long-term surface SO2. The results show that the population-weighted regional SO2 ([SO2]pw) increased from 2005 to 2007 and decreased steadily afterwards. The [SO2]pw decreased by 80.4% from 74.2 ± 28.4 µg/m3 in 2007 to 14.6 ± 4.8 µg/m3 in 2019. The predicted spatial distributions for each year show that the SO2 pollution was severe (more than 20 µg/m3) in most areas of Northern China until 2017. By using model interpretation methods, we visually reveal the mechanism of estimation bias in the back-extrapolation. Specifically, the training data is severely imbalanced with respect to the satellite-retrieved SO2 column densities (i.e., it is short on high-value samples), so the benchmark model is unable to extrapolate the effects of this important predictor. This study provides long-term surface SO2 data for post hoc evaluation and human exposure assessment in Northern China, while demonstrating that the interpretable machine learning approach is critical for model diagnostics and refinement. Leveraging satellite retrievals, the RBE-DA approach can be applied worldwide to back-extrapolate various measures of air quality.

A fast and high-efficiency electrochemical exfoliation strategy towards antimonene/carbon composites for selective lubrication and sodium-ion storage applications.

Two-dimensional (2D) layered antimony (Sb) materials are of importance due to their unique physicochemical properties, and they can be easily electrochemically exfoliated from bulk Sb in Na2SO4 electrolyte solution. However, the exfoliation yield is quite low and the exfoliated products are easily oxidized to Sb2O3, which prohibits their practical engineering applications. Herein, an antimonene/carbon composite is successfully fabricated with a high exfoliation yield through electrochemical exfoliation of bulk antimony chunk in a mixed electrolyte solution consisting of Na2SO4 and ethylene glycol. When the as-fabricated antimonene/carbon composite is added into PAO6 oil, the lubrication system exhibits a selective lubrication performance when sliding against GCr15 and YG8 ball, and the antiwear enhancement can be further improved by sliding against a YG8 ball. Besides, the antimonene/carbon composite can provide reliability and enough ion corridors during the charge/discharge processes. When tested as an anodic material for sodium-ion batteries, it exhibits a large capacity of 485.0 mA h g-1 at a current density of 200 mA g-1 after 150 cycles and a remarkable rate capability (334.5 mA h g-1 at 5 A g-1).

Key Factors in the Application of Sharestart to Enhance the Learning Attitude of Students.

Under the background of globalization and the popularity of distance learning ande-learning channels provided on the Internet, teaching methods that encourage the self-directed learning of students are becoming popular. There is an increasing number of domestic teachers joining in the practice for change. The various teaching methods that make the students acquire critical thinking skills can be summarized as learning by doing, critical thinking learning, multiple assessments, team discussion teaching, and cooperative learning. With the teachers of the universities in Shanghai as the questionnaire analysis objects, a total of 360 copies of questionnaires were distributed, and 256 valid copies were retrieved, with the retrieval rate of 71%. The research results are summarized as follows. (1) The "mental adaptation and engagement of students" is the most emphasized dimension, followed by the "professional development of teachers," "administration and parent support," and "material and teaching strategy." (2) The top five emphasized indicators, among 14, are the ordered cultivation of self-study and thinking habits, the development of the professional community for the collaborative lesson study of teachers, the support and cooperation of the president and the administration, adoption of heterogeneous grouping, and co-learning, discussion and cooperative learning. According to the results, it is expected to propose more definite practice directions for teachers intending to attempt such a teaching method, as well as provide some specific suggestions for the first movers of Sharestart.

Discussion of Students' E-book Reading Intention With the Integration of Theory of Planned Behavior and Technology Acceptance Model.

The emergence of e-books with the characteristics of easy access and reading any time anywhere is a subject of debate in academia. Topics include the use of e-books in libraries, their use in support teaching, new possibilities for reading activities, potential uses for library archives, and the motivation and intention of e-book users. Students at Guilin University of Technology participated in a survey. Of the 300 copies of the questionnaire distributed, 263 valid copies were returned, a retrieval rate of 88%. The research results show that (1) Usability and reading need are the key factors in e-book usage. Usability refers to convenient keyword searches, portability, and any time reading. E-books are considered to make searching and reading large amounts of data easier. (2) E-books are not restricted to time and space so that the overall reading quantity is increasing. Readers become accustomed to reading e-books, and the quality of their digital reading is gradually enhanced. (3) Students should complete e-book use courses offered by libraries to enhance their familiarity with e-books and their use of e-book software, thereby enhancing postgraduate student readers' e-book information literacy. The results of the research prompt suggestions to enhance the promotion of reading and e-book information to encourage student readers' e-book reading intention.

Assessing pesticide uses with potentials for down-the-drain transport to wastewater in California.

Pesticides and degradates are ubiquitously detected in municipal wastewater influent in the United States. However, little detailed information exists on their sources. The aim of this study is to investigate California Pesticide Use Report (PUR) and sales data to identify pesticide uses with a high potential for indoor down-the-drain (DtD) transport. The DtD transport of pesticides could result from direct applications to drains and sewers or through indirect activities such as washing pets, treated textiles, laundries, and cleaning surfaces treated with pesticides. An initial screening on pesticide products registered in California with DtD potentials showed that fipronil, imidacloprid, and seven pyrethroids were pesticides of concern due to the relatively high sales in DtD use patterns and high toxicity to aquatic organisms; and thus prioritized for additional evaluation. Uses and sales data of products containing the selected pesticides were analyzed for mass of active ingredient applied with specific DtD pathways and by different user groups. Professional uses were retrieved from the PUR and consumer uses were estimated by comparing PUR data to sales data. Overall, approximately 38,615 kg fipronil, 44,561 kg imidacloprid, and 240,550 kg pyrethroids were used annually in California from 2011 to 2015 with some likelihoods of DtD transport. The shares of professional use ranged from 56% (cypermethrin) to 98% (cyfluthrin), depending on the pesticide, with the majority of the mass applied in and around structures and for some pesticides (imidacloprid and permethrin) on landscapes as well. The remaining mass was applied by consumers on various DtD sources, including pet treatments (fipronil, imidacloprid, and permethrin), treated textiles (permethrin), indoor-only uses (cypermethrin), and mixed indoor/outdoor or outdoor-only applications (other pyrethroids). Results from this study help elucidate the relative significance of specific DtD pathways and pesticide occurrence in California waste streams.

A robust approach to deriving long-term daily surface NO2 levels across China: Correction to substantial estimation bias in back-extrapolation.

BACKGROUND: Long-term surface NO2 data are essential for retrospective policy evaluation and chronic human exposure assessment. In the absence of NO2 observations for Mainland China before 2013, training a model with 2013-2018 data to make predictions for 2005-2012 (back-extrapolation) could cause substantial estimation bias due to concept drift. OBJECTIVE: This study aims to correct the estimation bias in order to reconstruct the spatiotemporal distribution of daily surface NO2 levels across China during 2005-2018. METHODS: On the basis of ground- and satellite-based data, we proposed the robust back-extrapolation with a random forest (RBE-RF) to simulate the surface NO2 through intermediate modeling of the scaling factors. For comparison purposes, we also employed a random forest (Base-RF), as a representative of the commonly used approach, to directly model the surface NO2 levels. RESULTS: The validation against Taiwan's NO2 observations during 2005-2012 showed that RBE-RF adequately corrected the substantial underestimation by Base-RF. The RMSE decreased from 10.1 to 8.2 µg/m3, 7.1 to 4.3 µg/m3, and 6.1 to 2.9 µg/m3 in predicting daily, monthly, and annual levels, respectively. For North China with the most severe pollution, the population-weighted NO2 ([NO2]pw) during 2005-2012 was estimated as 40.2 and 50.9 µg/m3 by Base-RF and RBE-RF, respectively, i.e., 21.0% difference. While both models predicted that the national annual [NO2]pw increased during 2005-2011 and then decreased, the interannual trends were underestimated by >50.2% by Base-RF relative to RBE-RF. During 2005-2018, the nationwide population that lived in the areas with NO2 > 40 µg/m3 were estimated as 259 and 460 million by Base-RF and RBE-RF, respectively. CONCLUSION: With RBE-RF, we corrected the estimation bias in back-extrapolation and obtained a full-coverage dataset of daily surface NO2 across China during 2005-2018, which is valuable for environmental management and epidemiological research.

Water Quality Impairments Due to Aquatic Life Pesticide Toxicity: Prevention and Mitigation in California, USA.

The management of pesticides to protect water quality remains a significant global challenge. Historically, despite regulatory frameworks intended to prevent, minimize, and manage off-site movement of pesticides, multiple generations of pesticide active ingredients have created a seemingly unending cycle of pesticide water pollution in both agricultural and urban watersheds. In California, the most populous and most agricultural US state, pesticide and water quality regulators realized in the 1990s that working independently of each other was not an effective approach to address pesticide water pollution. Over the years, these California agencies have developed a joint vision and have continued to develop a unified approach that has the potential to minimize pesticide risks to aquatic life through a combination of prevention, monitoring, and management actions, while maintaining pesticide availability for effective pest control. Key elements of the current California pesticide/water quality effort include: 1) pesticide and toxicity monitoring, coupled with watershed modeling, to maximize information obtained from monitoring; 2) predictive fate and exposure modeling to identify potential risks to aquatic life for new pesticide products when used as allowed by the label or to identify effective mitigation measures; and 3) management approaches tailored to the different pesticide uses, discharge sources, physical environments, and regulatory environments that exist for agricultural runoff, urban runoff, and municipal wastewater. Lessons from this effort may inform pesticide management elsewhere in the world as well as other chemical regulatory programs, such as the recently reformed US Toxic Substances Control Act and California's Safer Consumer Products regulatory program. Environ Toxicol Chem 2020;39:953-966. © 2020 SETAC.

Determination of rheology and surface tension of airway surface liquid: a review of clinical relevance and measurement techniques.

By airway surface liquid, we mean a thin fluid continuum consisting of the airway lining layer and the alveolar lining layer, which not only serves as a protective barrier against foreign particles but also contributes to maintaining normal respiratory mechanics. In recent years, measurements of the rheological properties of airway surface liquid have attracted considerable clinical attention due to new advances in microrheology instruments and methods. This article reviews the clinical relevance of measurements of airway surface liquid viscoelasticity and surface tension from four main aspects: maintaining the stability of the airways and alveoli, preventing ventilator-induced lung injury, optimizing surfactant replacement therapy for respiratory syndrome distress, and characterizing the barrier properties of airway mucus to improve drug and gene delivery. Primary measuring techniques and methods suitable for determining the viscoelasticity and surface tension of airway surface liquid are then introduced with respect to principles, advantages and limitations. Cone and plate viscometers and particle tracking microrheometers are the most commonly used instruments for measuring the bulk viscosity and microviscosity of airway surface liquid, respectively, and pendant drop methods are particularly suitable for the measurement of airway surface liquid surface tension in vitro. Currently, in vivo and in situ measurements of the viscoelasticity and surface tension of the airway surface liquid in humans still presents many challenges.

Assessing Susceptibility of Debris Flow in Southwest China Using Gradient Boosting Machine.

A gradient boosting machine (GBM) was developed to model the susceptibility of debris flow in Sichuan, Southwest China for risk management. A total of 3839 events of debris flow during 1949-2017 were compiled from the Sichuan Geo-Environment Monitoring program, field surveys, and satellite imagery interpretation. In the cross-validation, the GBM showed better performance, with the prediction accuracy of 82.0% and area under curve of 0.88, than the benchmark models, including the Logistic Regression, the K-Nearest Neighbor, the Support Vector Machine, and the Artificial Neural Network. The elevation range, precipitation, and aridity index played the most important role in determining the susceptibility. In addition, the water erosion intensity, road construction, channel gradient, and human settlement sites also largely contributed to the formation of debris flow. The susceptibility map produced by the GBM shows that the spatial distributions of high-susceptibility watersheds were highly coupled with the locations of the topographical extreme belt, fault zone, seismic belt, and dry valleys. This study provides critical information for risk mitigating and prevention of debris flow.

Fiproles in urban surface runoff: Understanding sources and causes of contamination.

Urban-use pesticides present a unique risk to non-target organisms in surface aquatic systems because impervious pavement facilitates runoff that may lead to serious contamination and ensuing aquatic toxicity. Fipronil is an insecticide used at high rates in urban environments, especially in regions such as California. This compound and its biologically active degradation products have been detected in urban runoff drainage and downstream surface water bodies at concentrations exceeding toxicity thresholds for sensitive aquatic invertebrates, necessitating a better understanding of the runoff sources and causes of this contamination at sites of application. In this study, we evaluated sorption of fipronil, fipronil desulfinyl, fipronil sulfide, and fipronil sulfone in urban dust, soil, and concrete, matrices commonly associated with the perimeter of a residential home. Samples were also collected from five single family homes treated with fipronil in Riverside, California, for five months to determine the occurrence of fipronil and its degradates in runoff water, urban dust, soil, and on concrete surfaces. Statistical analysis was performed to determine which urban matrices contributed more significantly to the contaminant levels in runoff water. Freundlich sorption coefficients for fipronil and its degradation products in dust were 3- to 9-fold greater than their values in soil. Fipronil and its degradates were detected in 100% of runoff samples and their presence was observed in dust, soil, and concrete wipe samples for 153 d after the treatment. Linear regression analysis showed that concrete surfaces were a primary source of all four compounds to runoff, and loose dust on concrete pavement also served as an important contributor. This study represents the first comprehensive investigation of the sources and causes for surface runoff contamination by fipronil and its degradation products. Findings highlight the importance to reduce fipronil residues on concrete surfaces through improved application methods and other mitigation practices.

Environmental fate and impact assessment of thiobencarb application in California rice fields using RICEWQ.

Thiobencarb is a commonly used herbicide in Northern California rice fields. Released paddy water containing thiobencarb may pose ecological risks to non-targeted organisms. In this research, the Rice Water Quality Model (RICEWQ) is equilibrium tested and then calibrated using monitoring data at field level. Then it is employed to assess the environmental fate and impacts of thiobencarb in the Colusa Basin, and the effects of different management practices on water use and thiobencarb exposures. The model predicted thiobencarb concentrations from rice fields for multiple years throughout the Basin, using input from California Pesticide Use Reporting (PUR) database, and assessed both the temporal/spatial distribution of thiobencarb exposure and potential acute toxicity on non-target organisms. Our study indicated that RICEWQ can accurately reflect the initial partitioning of thiobencarb in both paddy water and soil phases and capture the dynamics of thiobencarb at field level after calibration. Mandatory water holding is critical for reducing thiobencarb exposure in released paddy water. A thirty-day holding time reduces thiobencarb concentrations by 64% relative to a 6-day holding practice. The geo-spatial pattern of exposure in the study domain indicates the differing extents of pollutant levels and their distribution over space. "Risk zones" for different species were identified based on the geospatial patterns of thiobencarb exposure and the species-specific susceptibilities of various non-target species to thiobencarb.

Regulatory Modeling of Pesticide Aquatic Exposures in California's Agricultural Receiving Waters.

For the aquatic exposure assessment of pesticides, the USEPA uses the Variable Volume Water Model (VVWM) to predict the estimated environmental concentrations (EECs) of a pesticide in a water body that receives runoff inputs from the Pesticide Root Zone Model (PRZM). The standard farm pond and additional generalized static and flowing water bodies used in endangered species assessment (aquatic bins) are used by USEPA to model the worst-case aquatic exposure for the nationwide exposure assessment. However, whether or not model results are relevant to state-specific conditions has not been validated. In this study, the USEPA water body scenarios are examined for their capability of providing a conservatively realistic estimate of pesticide aquatic exposures in California's agricultural settings. The sensitivity of modeled EECs to key water body parameters (dimensions, flow, and mass transfer) was explored with a one-at-a-time approach by using the standard farm pond as a baseline. The EECs generated from different USEPA water bodies for the worst-case loading were compared with the monitoring data observed in California's agriculturally influencing water bodies. Results showed that the farm pond EECs well captured the worst-case monitoring data, whereas the aquatic bins EECs, especially the flowing bins, tended to overestimate data. The conceptual model of the standard farm pond was also found to be relevant to the highly vulnerable water bodies in California's agricultural areas. The study confirms that VVWM with the standard farm pond scenario is appropriate for the screening-level regulatory exposure assessment in California's agricultural settings.

A nonparametric approach to filling gaps in satellite-retrieved aerosol optical depth for estimating ambient PM2.5 levels.

Satellite-retrieved aerosol optical depth (AOD) is commonly used to estimate ambient levels of fine particulate matter (PM2.5), though it is important to mitigate the estimation bias of PM2.5 due to gaps in satellite-retrieved AOD. A nonparametric approach with two random-forest submodels is proposed to estimate PM2.5 levels by filling gaps in satellite-retrieved AOD. This novel approach was employed to estimate the spatiotemporal distribution of daily PM2.5 levels during 2013-2015 in the Sichuan Basin of Southwest China, where the coverage rate of composite AOD retrieved by the Terra and Aqua satellites was only 11.7%. Based on the retrieved AOD and various covariates (including meteorological conditions and land use types), the first random-forest submodel (named AOD-submodel) was trained to fill the gaps in the AOD dataset, giving a cross-validation R2 of 0.95. Subsequently, the second random-forest submodel (named PM2.5-submodel) was trained to estimate the PM2.5 levels for unmonitored areas/days based on the gap-filled AOD, ground-monitored PM2.5 levels, and the covariates, and achieved a cross-validation R2 of 0.86. By comparing the complete and incomplete (i.e., without the days when AOD data were missing) estimates, we found that the monthly PM2.5 levels could be overestimated by 34.6% if the PM2.5 values coincident with AOD gaps were not considered. The newly developed approach is valuable for deriving the complete spatiotemporal distribution of daily PM2.5 from incomplete remote-sensing data, which is essential for air quality management and human exposure assessment.