Search Results (226)

Developing a water-soluble and chlorine-free palladium compound to replace conventional PdCl₂ or Pd(NO₃)₂ as the precursor for Pd-based catalysts remains both challenging and of considerable significance for highly efficient degradation of volatile organic compounds (VOCs). Herein, we report a facile synthetic route to such a Pd compound, (NH₄)₂[Pd(C₂O₄)₂]·2H₂O (denoted as Pd-X5), via a three-step reaction starting from PdCl₂, under mild and readily controllable conditions, rendering the process amenable to industrial manufacture. The molecular structure of Pd-X5 was confirmed mainly by elemental analysis, FT-IR, and ¹³C NMR. The overall yield was greater than 95% and the content of residual chloride was reduced to below 100 ppm. Pd-X5 exhibited high water solubility of 350 g L⁻¹. Subsequently, Pd-X5 was used as a catalytic precursor, and a Pd/Al₂O₃ catalyst was prepared by an impregnation technique and evaluated for its catalytic performance in the degradation of VOCs. Compared with Pd(NO₃)₂-derived Pd/Al₂O₃, the Pd-X5-based catalyst exhibited markedly enhanced activity for the oxidation of CH₄ and C₃H₈ at different temperatures and under different contents of water vapor, indicating that Pd-X5 is superior to Pd(NO₃)₂ as a catalytic precursor and has potential application in the production of Pd-based catalysts. Full article

At subsurface waste disposal sites, degradation of containment materials can cause leaks of chlorinated volatile organic compounds (Cl-VOCs) in the vadose zone. Material Disposal Area L (MDA L) is a heavily monitored waste site at Los Alamos National Laboratory in Northern New Mexico where a sharp increase in contaminant concentrations was measured in February 2019. Subsequently, soil vapor extraction (SVE) was performed as part of an ongoing interim measure. Here, we demonstrate a new method to introduce possible leakage within an existing numerical framework to bound possible leakage related to concentration increases seen in site monitoring data. A previously calibrated three-dimensional (3-D) model for SVE at MDA L is used to simulate the three conceptual stages from June 2017 to July 2024. The three conceptual stages based on the observed events are: leakage, passive diffusion, and soil vapor extraction. We use a 3-D multiphase flow simulator to introduce a simulated leak and attempt to approximately match monitoring data collected in February 2019, May 2024, and July 2024. After approximately matching the observed leak, outputs from the 3-D simulations were used to quantify the simulated mass of Cl-VOC leaked. Simulated results for a leak on the order of 40 kg of Cl-VOC showed general agreement with the monitoring data. Although the solution is non-unique, this paper presents a proof-of-concept addition to an existing case study, to show that a suspected subsurface container failure could create a signal consistent with the measured data and sets the stage for further analysis of future potential leak signals at the site. The work can also be adapted at other sites where changing subsurface conditions can require innovative modeling techniques to answer regulatory questions. Full article

Photodynamic therapy (PDT) represents a promising non-antibiotic strategy for addressing bacterial and fungal infections, particularly in the context of increasing antimicrobial resistance and biofilm-associated disease. PDT is based on the light-induced activation of photosensitizers, leading to the generation of reactive oxygen species (ROS), including singlet oxygen (¹O₂), which induce oxidative damage to multiple microbial targets. Unlike conventional antimicrobial drugs that often act through specific molecular pathways, antimicrobial PDT produces simultaneous damage to membranes, proteins, nucleic acids, and extracellular biofilm components, thereby reducing the probability of resistance development. This review critically analyzes the cellular, biochemical, and biophysical determinants that govern PDT selectivity toward bacterial and fungal cells in comparison with mammalian host tissues. Particular attention is given to photosensitizer localization, membrane interactions, photobleaching, oxygen dependence, light penetration, and the balance between Type I and Type II photochemical mechanisms. The review provides a comparative overview of major molecular photosensitizer classes, including phenothiazines, porphyrins, chlorins, phthalocyanines, xanthene dyes, natural polyphenols, endogenous compounds, and advanced targeted photosensitizers. In addition, this review distinguishes molecular photosensitizers from nanotechnology-based platforms and delivery systems. Nanoparticles, polymeric carriers, hydrogels, and light-activated coatings are discussed not only as photosensitizer delivery tools, but also as systems that modulate aggregation, improve localization, enhance biofilm penetration, and enable surface-confined ROS generation. ROS are capable of causing phototoxic effects wherever they are located. Unless selectively accumulated by target organisms, there can be systemic phototoxicity. Overall, PDT should be regarded as a modular antimicrobial platform in which photosensitizer chemistry, formulation, light delivery, oxygen availability, and infection biology must be co-optimized. Although further studies are required to address clinical translation, regulatory complexity, material safety, and standardized treatment protocols, PDT offers a scientifically robust and clinically relevant approach that may complement conventional antibacterial and antifungal therapies, especially in localized, biofilm-associated, and device-related infections. Full article

Chlorophenols (CPs), such as 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP), are persistent and toxic organic pollutants commonly found in industrial effluents. This study investigates their photocatalytic degradation using a TiO₂-based heterogeneous catalyst under UV irradiation, in the presence of hydrogen peroxide. The degradation kinetics were analyzed using both pseudo-first order and nonlinear Langmuir–Hinshelwood (L–H) models, accounting for competitive adsorption and successive oxidation of intermediates. Gas chromatography–mass spectrometry (GC–MS) identified key intermediates, including hydroquinone, catechol, chlorocatechols, and benzoquinone. Nonlinear kinetic modeling of coupled differential equations accurately reproduced the temporal profiles of both the parent compounds and their intermediates, providing mechanistic insights into multi-step hydroxylation, dechlorination, and oxidation processes. The results demonstrate that photocatalytic oxidation effectively mineralizes chlorophenols within 500–600 min, and the developed kinetic model offers a predictive tool for optimizing photocatalytic remediation strategies for chlorinated aromatic pollutants. The novelty of this study lies in the development of a nonlinear Langmuir–Hinshelwood kinetic model integrating experimentally identified degradation intermediates, competitive adsorption phenomena, and parallel photocatalytic reaction pathways for both 4-chlorophenol and 2,4-dichlorophenol oxidation systems. Full article

The efficient capture of chlorinated volatile organic compounds (Cl-VOCs) represents a significant challenge in environmental protection and sustainable chemical engineering. In this study, a functional deep eutectic solvent (DES) composed of tetrabutylphosphonium bromide ([P₄₄₄₄][Br]) and levulinic acid (LEV) at a 1:2 molar ratio was prepared, and its absorption performance toward two typical Cl-VOCs, namely dichloromethane (DCM) and chloroform (TCM), was evaluated using this DES as a recyclable absorbent. Based on COSMO-SAC model predictions and experimental validation, the [P₄₄₄₄][Br]-LEV (1:2) system was identified as the preferred candidate. Under mild conditions (10 °C, N₂ flow rate of 100 mL/min), the saturated absorption capacities of this DES reached 1521.71 mg/g and 1620.30 mg/g for DCM and TCM, respectively. The absorbent exhibited favorable regeneration stability over five consecutive absorption–desorption cycles, retaining over 90% of its initial absorption efficiency. Mechanistic studies, including proton nuclear magnetic resonance (¹H NMR), Fourier-transform infrared spectroscopy (FT-IR), DSC (Differential Scanning Calorimetry), TGA (Thermogravimetric Analysis) and quantum chemical calculations, including electrostatic potential (ESP), independent gradient model (IGM), and reduced density gradient (RDG), demonstrated that the absorption process was dominated by physical interactions such as hydrogen bonding and van der Waals forces, with no chemical reactions involved. At the laboratory scale, this DES system showed excellent Cl-VOCs absorption performance, providing a useful reference for the rational design of high-efficiency VOC absorbents. Full article

The combined effects of organic pollutants and vertical soil gradients on microbial community assembly in long-term contaminated sites remain insufficiently understood. In this study, high-throughput sequencing was employed to characterize prokaryotic communities across depth-resolved soil profiles at a contaminated site in Tianjin, China. Microbial diversity, taxonomic composition, and predicted functional traits varied significantly with soil depth and pollutant distribution. Surface soils exhibited higher richness and diversity, with Shannon, Sobs, and PD indices decreasing with depth (p = 0.020, p = 0.002, and p < 0.001, respectively). Redundancy analysis showed that the first two axes explained 89.91% of the total variance, indicating strong associations between microbial community structure and environmental variables. Community differentiation was related to pollutant type, with aromatic hydrocarbons more strongly linked to surface assemblages and chlorinated compounds associated with deeper horizons. Although the overall abundance of predicted metabolic genes decreased with depth, the distribution of major functional categories, including pathways related to organic matter degradation, remained comparatively stable. Co-occurrence network analysis revealed a progressive decline in network connectivity and complexity along the vertical gradient, with the number of edges decreasing from 853 (L1) to 447 (L3) and average degree decreasing from 16.404 to 9.122. These findings highlight depth-related environmental filtering as a key mechanism structuring microbial communities under long-term organic contamination and provide a scientific basis for optimizing depth-specific in situ bioremediation strategies, such as targeting aromatic hydrocarbon degradation in surface soils and chlorinated compound remediation in deeper layers. Full article

This paper presents the results of a laboratory-based treatability study conducted for a confidential former wood treating site heavily impacted by a creosote non-aqueous-phase liquid (NAPL) containing pentachlorophenol (PCP). PCP impacts in the silty sands extended to approximately 33 ft (10 m) below the ground surface (bgs), with discrete soil samples containing PCP concentrations up to 14,500 mg/kg, and groundwater PCP concentrations forming a main plume exceeding 1 mg/L over 2.16 acres (0.87 ha). Treatability testing was performed on unspiked and NAPL-spiked site soils with total PCP concentrations ranging from 10 to 100 mg/kg, respectively, and leachable PCP concentrations of approximately 3 to 8 mg/L. Stabilization/solidification (S/S) mix designs using 5 to 10 weight percent (wt%, dry-reagent-to-wet-soil mass basis) of a Portland cement (PC) blend and 1 wt% powdered bentonite met the minimum unconfined compressive strength (UCS) and maximum hydraulic conductivity (K) performance criteria of 50 lb/in2 (345 kPa) and 1 × 10⁻⁶ cm/s, respectively, within the specified 28-day cure time. Long-term semi-dynamic leach testing was performed on S/S-treated soils using a modified United States Environmental Protection Agency (EPA) Method 1315 test incorporating a polydimethylsiloxane (PDMS) liner to improve the data reliability for hydrocarbons. Results showed that adding 1 wt% organoclay (OC) to the S/S mix designs did not substantially reduce leaching of common semi-volatile organic compounds (SVOCs) such as naphthalene, acenaphthene, phenanthrene and benzo(a)anthracene compared to mixes using only the PC blend with bentonite, consistent with previous studies. However, the inclusion of OC had a decisive effect on PCP immobilization, providing an order-of-magnitude (10×) reduction in the cumulative mass release of PCP over the test duration. This benefit diminished with decreasing degree of chlorination for other phenolic compounds. Full article

The development of low-temperature, high-efficiency catalysts for the catalytic elimination of chlorinated volatile organic compounds (CVOCs) remains a significant challenge. Investigating the influence mechanism of catalyst physicochemical properties on chlorobenzene oxidation performance and degradation pathways is particularly important. CuO/WO₃ catalysts were developed using a hydrothermal method in this work. The effects of simultaneous or separate addition of ammonium sulphate and ammonium persulphate on the catalytic performance of the CuO/WO₃ series catalysts were investigated. The results showed that the introduction of ammonium sulphate alone can facilitate the formation of CuWO₄, thereby increasing the chemisorbed oxygen concentration of the CuO/WO₃, and making the overall structure of the catalyst looser and increasing the active sites on the catalyst surface. As the optimal catalyst, CuO/WO₃-2 exhibited 55.9% of chlorobenzene conversion and 32.9% of CO₂ selectivity at 500 °C. Interestingly, although the surface acidity in this work seemed to be one of the reasons for promoting the chlorobenzene oxidation, it could be clearly found that the strong solid acidity of WO₃ was actually a key factor in inhibiting the chlorobenzene oxidation. Finally, based on in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis, the primary mechanism for chlorobenzene oxidation on CuO/WO₃ catalysts proceeds through a sequential conversion: chlorobenzene was first transformed into phenolic intermediates, followed by quinone compounds, maleates, aldehydes, bidentate carbonates, and ultimately carbonate species. Full article

Among the most important species of Ficus L. genus are F. deltoidea, F. exasperata, F. sycomorus, F. religiosa, F. microcarpa, F. hirta Vahl., F. benghalensis, F. racemosa, F. elastica, and F. carica. The genus has more than 30 traditional ethnomedicinal uses, attributed to the combination of different bioactive compounds, including flavonoids, (flavanols, flavones, flavonols, isoflavones, chalcones, anthocyanins), phenolic acids (hydroxycinnamic acids, hydroxybenzoic acids), terpenes (triterpenes, tetraterpenes, diterpenes, sesquiterpenes, monoterpenes), phytosterols, coumarins, hydroxybenzoates, phenylpropanoids, chlorins, pheophytins, megastigmans, chitinases, organic acids, fatty acids, amino acids, alkaloids, and glycosides. With this in mind, the objective of this manuscript was to conduct a scientific search in the main electronic databases (PubMed, SciELO, Latindex, Redalyc, BiologyBrowser, ScienceResearch, ScienceDirect, World Wide Science, Web of Science, Academic Journals, Etnobotany, Scopus, and Google Scholar) to gather information on published research regarding the genoprotective potential of the Ficus L. genus. Unlike most scientific articles, which primarily describe the individual characteristics and properties of each species, this document compiles the largest number of studies (in vitro and in vivo) on Ficus plants described by different authors. Thus, we aim to promote more detailed scientific research and expand studies on the protective capacity of these angiosperm plants to the genetic material. Full article

Parkinson’s disease (PD) is a complex neurodegenerative disorder influenced by age, genetic predispositions, and environmental exposures, with a growing global incidence. This review aims to summarize findings from ATSDR Toxicological Profiles, EPA Risk Assessments, and other sources of peer-reviewed literature to examine the potential associations between PD and select metals, pesticides, and chlorinated organic compounds. Additionally, it explores using computational toxicology methods to elucidate the interactions between specific chemicals, associated genes, and their possible roles in PD. A total of 29 substances were identified to be neurotoxic with direct or probable association with PD. Risk of disease onset or symptom exacerbation of PD has been linked to exposures to neurodegenerative metals, pesticides, chlorinated organic compounds, and other environmental toxicants, alongside intrinsic factors such as genetic predisposition and aging. Supporting evidence from neurotoxicological studies directly or possibly associated with PD are summarized in referenced toxicological profiles and EPA risk assessments. Genotoxic endpoints evaluated in exposure-induced neurodegeneration including oxidative stress, DNA strand breaks, mitochondrial dysfunction, impaired DNA repair, and telomere alterations may play a critical role in linking environmental exposures to PD pathogenesis. Although these endpoints represent imperative data gaps between environmental and genetic risk factors for PD, isolating individual substances may not be necessary for prevention, as many co-occur at contaminated sites or within certain occupations. Further research is needed to clarify causal relationships between environmental exposure and genotoxic endpoints seen in neurodegenerative processes that can also be seen in PD for consideration in the development of preventive and therapeutic strategies. Full article

Environmental contamination caused by various types of heavy metals and chlorinated organic compounds poses a significant threat to global ecosystems. While bioremediation offers a sustainable solution, identifying microbial strains that possess the metabolic versatility to withstand metal toxicity and degrade persistent organic pollutants remains a major challenge. In this study, we characterized strain TW-R-39-2, a novel bacterium isolated from a wastewater treatment plant. Phylogenomic analysis based on complete genome sequencing revealed that strain TW-R-39-2 represents a novel species within the genus Dechloromonas, showing Average Nucleotide Identity (ANI) and digital DNA–DNA hybridization (dDDH) values of 80.17% and 23.4%, respectively, with its closest relative, Dechloromonas denitrificans. Genomic insights revealed a 3.46 Mb circular chromosome containing a diverse array of genes associated with heavy metal resistance (e.g., predicted czc and cadA clusters) and chlorinated compound degradation (e.g., dehalogenases). Phenotypic assays validated these genomic predictions, demonstrating the strain’s dual functionality: it exhibited high adsorption efficiencies for cadmium (Cd²⁺, 78.0%) and zinc (Zn²⁺, 75.1%), alongside significant degradative capacity for trichloroethylene (TCE, 83.6%) and chlorophenol (81.0%) within a 7-day incubation period, corresponding to the strain’s active growth and early stationary phases. The stoichiometric release of chloride ions confirmed the complete dechlorination of the organic pollutants. These findings demonstrate that strain TW-R-39-2 possesses versatile capacities for both the sequestration of toxic metals and the biodegradation of persistent organic compounds. This study highlights the potential of strain TW-R-39-2 as a promising candidate for the efficient bioremediation of diverse industrial wastewaters. Full article

Microplastics (MPs) represent pervasive contaminants in aquatic ecosystems, acting as carriers for persistent organic pollutants like polycyclic aromatic hydrocarbons (PAHs). This study systematically investigated the occurrence, composition, and ecological risks of MPs and adsorbed polycyclic aromatic hydrocarbons in urban drainage sediments from three Yangtze River cities: Chongqing (Yongchuan), Changzhou (Jintan), and Shanghai (Tongji University campus). The key findings revealed MPs’ abundances ranging from 130 to 564 items/100 g (mean: 346 items/100 g), with peak concentrations in campus commercial areas (498.4 items/100 g) and academic zones (420 items/100 g). Predominant polymers included polypropylene (PP, 15.29%), polyethylene terephthalate (PET, 15.88%), and chlorinated polyethylene (CPE, 14.98%). Granular MPs (75–300 μm) dominated particle size (50.09%), while colored MPs (66.54%)—particularly red (32.84%) and black (27.92%)—were most prevalent. Polycyclic aromatic hydrocarbons adsorbed on MPs ranged from 0.88 to 120.59 ng/g (mean: 5.76–67.66 ng/g), dominated by four-ring compounds (44.59%). Sediment-associated polycyclic aromatic hydrocarbons ranged from 0.63 to 60.09 ng/g (mean: 2.12–36.96 ng/g), with 5–6-ring polycyclic aromatic hydrocarbons (42%) as primary constituents. Significant correlations emerged between four-ring polycyclic aromatic hydrocarbons and fibrous MPs (r = 0.33, p = 0.021) and black MPs (r = 0.23, p = 0.04). This study underscores urban drainage sediments as critical reservoirs and transport pathways for MPs and polycyclic aromatic hydrocarbons, which is crucial for sustainable management for urban drainage systems. We advocate for implementing targeted management strategies that prioritize three interconnected approaches: enhanced monitoring of high-risk zones (particularly commercial areas), focused control of small-sized MPs (<300 μm) due to their elevated ecological threats, and systematic mitigation of PAH-MP co-contamination in densely populated catchments to disrupt pollutant transmission pathways. Full article

Obtaining the adsorption equilibrium coefficient (K_d) of organic compounds on microplastics (MPs) is critical for understanding their environmental behaviors. Given the limited availability of these K_d values, it is imperative to develop predictive models for rapid acquisition of K_d values for different MPs. Herein, seven machine learning-based algorithms, i.e., MLR, RF, GBDT, XGBoost, CatBoost, LightGBM and SVM, were used to establish predictive models on the basis of 173 logK_d values in freshwater. The evaluation parameters, including R²_t, RMSE_t, Q²_v, RMSE_v and Q², indicate that the developed models have a satisfactory predictive capability. The developed MLR models can predict the logK_d values for chlorinated polyethylene (CPE), polybutylene succinate (PBS), polycaprolactone (PCL) and low-density polyethylene (LDPE) MPs. Given the limited performance of MLR in predicting adsorption on PE MPs, RF, GBDT, XGBoost, CatBoost, LightGBM and SVM were employed to develop predictive models, which significantly enhanced the predictive accuracy. The predictive models for PE MPs have a wider AD, covering organic compounds with different functional groups than previous models. Hydrogen bonding, hydrophobic, electrostatic and dispersion interactions may be involved in adsorption. The developed models can serve as efficient tools for estimating the K_d values for different MPs in freshwater, thereby providing the necessary data for evaluating the environmental risks of organic compounds and MPs. Full article

Steroidal compounds lie at the crossroads of inflammation and cancer, where modulation of common signaling pathways creates opportunities for dual-action therapeutic intervention. Accumulating evidence indicates that their anti-inflammatory and antitumor activities are frequently interconnected, reflecting shared molecular mechanisms that regulate immune signaling, oxidative stress, cell proliferation, and apoptosis. This review provides a critical and comparative analysis of major classes of bioactive steroids—including furanosteroids, neo-steroids, aromatic steroids, α,β-epoxy steroids, peroxy steroids, cyanosteroids, nitro- and epithio steroids, halogenated steroids (fluorinated, chlorinated, brominated, iodinated), and steroid phosphate esters—with emphasis on their dual anti-inflammatory and anticancer potential. More than one thousand steroidal metabolites derived from plants, fungi, marine organisms, bacteria, and synthetic sources are surveyed. While the majority exhibit either anti-inflammatory or antineoplastic activity alone, only a limited subset displays potent activity in both domains. Comparative evaluation highlights the structural features that favor dual functionality, including epoxide, peroxide, nitrile, nitro, halogen, and phosphate ester moieties, as well as rearranged or heteroatom-enriched steroidal frameworks. Where available, biological data from in vitro and in vivo assays (IC₅₀ values, enzyme inhibition, cytokine modulation, and antiproliferative effects) are summarized and critically compared. Special attention is given to rare natural metabolites—such as polyhalogenated marine steroids, phosphorylated sterols, and heteroatom-containing derivatives—as well as synthetic analogues designed to enhance cytotoxic or immunomodulatory efficacy. Mechanistically, steroids exhibiting dual activity commonly modulate convergent signaling pathways, including NF-κB, JAK/STAT, MAPK, PI3K/AKT, redox homeostasis, and apoptosis regulation. Collectively, these findings underscore the potential of structurally optimized steroids as multifunctional therapeutic agents and provide a framework for the rational design of next-generation anti-inflammatory and anticancer drugs. Full article

Listeria monocytogenes biofilms on surfaces that come into contact with food create ongoing challenges in produce-processing environments, highlighting the necessity for effective surface sanitation. This research examined the effectiveness of chlorine (200 ppm), quaternary ammonium compound (QAC, 400 ppm), and UV-C light (0.85 J/cm²) against L. monocytogenes biofilms developed on stainless steel, polyethylene terephthalate (PET), and silicone rubber materials frequently used in apple packing settings. Biofilms were cultivated using a mixture of LCDC and V7 strains in diluted apple juice and evaluated after 1 and 7 days of growth. The type of surface material and the age of the biofilm had a significant impact on the performance of the sanitizing agents (p < 0.05). Chlorine achieved a reduction of 2.84 ± 0.06 log CFU/coupon on 1-day-old biofilms on stainless steel, although its effectiveness dropped to 1.90 ± 0.07 log CFU/coupon on biofilms aged 7 days. Similar trends were noted for QAC (2.42 ± 0.05 to 1.73 ± 0.06 log CFU/coupon) and UV-C (2.71 ± 0.05 to 1.57 ± 0.08 log CFU/coupon) over time. PET and silicone rubber consistently exhibited lower log reductions than stainless steel for all treatments. The presence of organic matter from apple juice reduced the efficacy of sanitizers on all surfaces. These results emphasize the significant role of surface material, biofilm age, and organic load on sanitation effectiveness, offering practical recommendations for enhancing the control of L. monocytogenes in produce-processing facilities. Full article