Elevated concentrations of heavy metals in agricultural soils threatening ecological security and the quality of agricultural products, and apportion their sources accurately is still a challenging ...task. Multivariate statistical analysis, GIS mapping, Pb isotopic ratio analysis (IRA), and positive matrix factorization (PMF) were integrated to apportion the potential sources of heavy metal(loid)s of orchard soil in Karst-regions. Study region soils were moderately contaminated by Cd. Obvious enrichment and moderate contamination level of Cd were found in study region surface soils, followed by As, Zn, and Pb. Correlation analysis (CA) and principal component analysis (PCA) indicated Ba, Co, Cr, Ni, V were mainly from natural sources, while As, Cd, Cu, Pb, Zn were derived from two kinds of anthropogenic sources. Based on Pb isotope composition, atmospheric deposition and livestock manure were the main sources of soil Pb accumulation. Further source identification and quantification results with PMF model and GIS mapping revealed that soil parent materials (46.44%) accounted for largest contribution to the soil heavy metal(loid)s, followed by fertilizer application (31.37%) and mixed source (industrial activity and manure, 22.19%). Uncertainty analysis indicated that the three-factors solution of PMF model was an optimal explanation and the heavy metal(loid) with lower percentage contributions had higher uncertainty. This study results can help to illustrate the sources of heavy metals more accurately in orchard agricultural soils with a clear expected future for further applications.
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•An integration method was proved as an effective source appointment approach.•Cd was the most serious contaminated element in the soil.•Heavy metal(loid)s were from soil parent materials and agricultural activities.•Larger uncertainty was accompanied by lower percentage contributions in PMF model.
The integrated method (PCA-CA, GIS-IRA, PMF) was proved as an efficient and reliable approach to identify and quantify the heavy metal contamination sources of agricultural soils.
Nanotechnology has recently emerged as a rapidly growing field with numerous biomedical science applications. At the same time, silver has been adopted as an antimicrobial material and disinfectant ...that is relatively free of adverse effects. Silver nanoparticles possess a broad spectrum of antibacterial, antifungal and antiviral properties. Silver nanoparticles have the ability to penetrate bacterial cell walls, changing the structure of cell membranes and even resulting in cell death. Their efficacy is due not only to their nanoscale size but also to their large ratio of surface area to volume. They can increase the permeability of cell membranes, produce reactive oxygen species, and interrupt replication of deoxyribonucleic acid by releasing silver ions. Researchers have studied silver nanoparticles as antimicrobial agents in dentistry. For instance, silver nanoparticles can be incorporated into acrylic resins for fabrication of removable dentures in prosthetic treatment, composite resin in restorative treatment, irrigating solution and obturation material in endodontic treatment, adhesive materials in orthodontic treatment, membrane for guided tissue regeneration in periodontal treatment, and titanium coating in dental implant treatment. Although not all authorities have acknowledged the safety of silver nanoparticles, no systemic toxicity of ingested silver nanoparticles has been reported. A broad concern is their potential hazard if they are released into the environment. However, the interaction of nanoparticles with toxic materials and organic compounds can either increase or reduce their toxicity. This paper provides an overview of the antibacterial use of silver nanoparticles in dentistry, highlighting their antibacterial mechanism, potential applications and safety in clinical treatment.
Heavy-metal pollution of soil is a serious issue worldwide, particularly in China. Soil remediation is one of the most difficult management issues for municipal and state agencies because of its high ...cost. A two-year phytoremediation project for soil contaminated with arsenic, cadmium, and lead was implemented to determine the essential parameters for soil remediation. Results showed highly efficient heavy metal removal. Costs and benefits of this project were calculated. The total cost of phytoremediation was US$75,375.2/hm2 or US$37.7/m3, with initial capital and operational costs accounting for 46.02% and 53.98%, respectively. The costs of infrastructures (i.e., roads, bridges, and culverts) and fertilizer were the highest, mainly because of slow economic development and serious contamination. The cost of phytoremediation was lower than the reported values of other remediation technologies. Improving the mechanization level of phytoremediation and accurately predicting or preventing unforeseen situations were suggested for further cost reduction. Considering the loss caused by environmental pollution, the benefits of phytoremediation will offset the project costs in less than seven years.
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•A two-year phytoremediation project was introduced.•Costs and benefits of a phytoremediation project were calculated.•Costs of phytoremediation project can be offset by benefits in 7years.
With the rapid development of modern industry, heavy metals in the soil introduce the risk of serious pollution. To reduce this pollution risk, the following four research questions needed to be ...addressed: What are the main influencing factors of soil pollution? What is the degree of influence? Do factors operate independently or are they interconnected? Which regions have high pollution risk and should be paid more attention? The study area was in Huanjiang County, with 273 km2, and geographical detector proved to be a useful tool to solve these four problems. We found that mine activity and pH value were the primary influencing factors for total and water-soluble heavy metals. The interaction effects of mine activity and soil type, pH values, and normalized difference vegetation index (NDVI) for total heavy metals, as well as pH value and mine activity for water-soluble heavy metals, were greater than the sum effect of two factors. Zones with a high concentration of heavy metals were closer to the road and farther from the mine area, which had low NDVI, large slope, high terrain, and large pH values. Concentrations of total heavy metals were higher in calcareous soils and in dryland and forests. Zones with a higher concentration of water-soluble heavy metals were closer to the mine and river, which had lower DEM and pH values. The uncertainty of geographical detector was also analyzed on the basis of their interpolation accuracy and the stratification number of influencing factors, and we found that the existing sample numbers and the stratification number of influencing factors met the needs of geographical detector calculation. This study's conclusions are useful for soil pollution control and restoration.
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•Quantitatively identified the main influencing factors on the spatial distribution of pollutants in the soil.•Quantitatively analyzed the interaction effect of factors on the spatial distribution of pollutants in the soil.•Identified the potential zones at risk for pollution in the soil, where should be pay more attention.
The matrix proteins of Staphylococcus aureus biofilm have not been well defined. Previous efforts to identify these proteins were performed using in vitro systems. Here we use a proteomic approach to ...identify biofilm matrix proteins directly from infected bone implants using a rat model of orthopedic implant-associated S. aureus infection. Despite heavy presence of host proteins, a total of 28 and 105 S. aureus proteins were identified during acute infection and chronic infection, respectively. Our results show that biofilm matrix contains mostly intracellular cytoplasmic proteins and, to a much less extent, extracellular and cell surface-associated proteins. Significantly, leukocidins were identified in the biofilm matrix during chronic infection, suggesting S. aureus is actively attacking the host immune system even though they are protected within the biofilm. The presence of two surface-associated proteins, Ebh and SasF, in the infected bone tissue during acute infection was confirmed by immunohistochemistry. In addition, a large number of host proteins were found differentially expressed in response to S. aureus biofilm formed on bone implants.
Summary
Plants endure challenging environments in which they are constantly threatened by diverse pathogens. The soil‐borne fungus Verticillium dahliae is a devastating pathogen affecting many plant ...species including cotton, in which it significantly reduces crop yield and fiber quality. Melatonin involvement in plant immunity to pathogens has been reported, but the mechanisms of melatonin‐induced plant resistance are unclear. In this study, the role of melatonin in enhancing cotton resistance to V. dahliae was investigated. At the transcriptome level, exogenous melatonin increased the expression of genes in phenylpropanoid, mevalonate (MVA), and gossypol pathways after V. dahliae inoculation. As a result, lignin and gossypol, the products of these metabolic pathways, significantly increased. Silencing the serotonin N‐acetyltransferase 1 (GhSNAT1) and caffeic acid O‐methyltransferase (GhCOMT) melatonin biosynthesis genes compromised cotton resistance, with reduced lignin and gossypol levels after V. dahliae inoculation. Exogenous melatonin pre‐treatment prior to V. dahliae inoculation restored the level of cotton resistance reduced by the above gene silencing effects. Melatonin levels were higher in resistant cotton cultivars than in susceptible cultivars after V. dahliae inoculation. The findings indicate that melatonin affects lignin and gossypol synthesis genes in phenylpropanoid, MVA, and gossypol pathways, thereby enhancing cotton resistance to V. dahliae.
Significance Statement
This study unveils that melatonin plays a role in the interaction between cotton and a fungal pathogen. Melatonin affects lignin and gossypol synthesis genes in phenylpropanoid, MVA, and gossypol pathways, thereby enhancing cotton resistance to Verticillium dahliae.
The increasing demand for high food quality and safety, and concerns of environment sustainable development have been encouraging researchers in the food industry to exploit the robust and green ...biodegradable nanocomposites, which provide new opportunities and challenges for the development of nanomaterials in the food industry. This review paper aims at summarizing the recent three years of research findings on the new development of nanomaterials for food packaging. Two categories of nanomaterials (i.e., inorganic and organic) are included. The synthetic methods, physical and chemical properties, biological activity, and applications in food systems and safety assessments of each nanomaterial are presented. This review also highlights the possible mechanisms of antimicrobial activity against bacteria of certain active nanomaterials and their health concerns. It concludes with an outlook of the nanomaterials functionalized in food packaging.
Intercropping of arsenic (As) hyperaccumulator and cash crops during remediation of contaminated soil has been applied in farmland remediation project. However, little is known about the fate of As ...fractions in the soil profile and As uptake within the intercropping plants under field condition. In this study, As removal, uptake, and translocation were investigated within an intercropping system of Pteris vittata L. (P. vittata) and maize (Zea mays). Results indicated that the concentration of As associated with amorphous Fe (hydr)oxides in the 10–20 cm soil layer was significantly lower under malposed intercropping of P. vittata and maize, and As accumulation in P. vittata and biomass of P. vittata were simultaneously higher under malposed intercropping than under coordinate intercropping, leading to a 2.4 times higher rate of As removal. Although maize roots absorbed over 13.4 mg kg−1 As and maize leaves and flowers accumulated over 21.5 mg kg−1 As (translocation factor higher than 1), grains produced in all intercropping modes accumulated lower levels of As, satisfying the standard for human consumption. Our results suggested that malposed intercropping of a hyperaccumulator and a low-accumulation cash crop was an ideal planting pattern for As remediation in soil. Furthermore, timely harvest of P. vittata, agronomic strategies during remediation, and appropriate management of the above ground parts of P. vittata and high-As tissues of cash crops may further improve remediation efficiency.
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•Concentration of AsF3 in the soil layer of 10–20 cm decreased under malposed intercropping.•Arsenic accumulation in P. vittata in malposed intercropping mode was high.•Arsenic removal in malposed intercropping mode was enhanced 2.4 times.•The grain of maize under all intercropping conditions satisfied foods standard for As concentration.
Solar‐driven photocatalytic nitrogen fixation is a low‐energy and environmentally friendly strategy for NH3 synthesis, which is considered as a possible alternative to the Haber‐Bosch (HB) process. ...Considering the extremely high bond energy of N2, the choice of photocatalysts is essential for nitrogen reduction reaction (NRR). As a class of porous materials with high crystallinity and adjustable organic ligands, metal‐organic frameworks (MOFs) have been proven to exhibit high photocatalytic activity for a lot of reactions. Recently, MOFs and MOF‐based functional materials have become a kind of promising photocatalysts for NRR. In this minireview, we provide a comprehensive overview of the work reported so far on the MOF and MOF‐derived photocatalysts for the nitrogen fixation. Through the comprehensive analysis of the structures, nitrogen fixation performances and mechanisms of these photocatalysts, this minireview provides a reference for the design of new photocatalysts based on MOF materials.
As a class of crystalline porous materials, metal‐organic frameworks (MOFs) exhibit high photocatalytic activity for a lot of important reactions. This minireview aims to provide an overview of recent advances in MOF‐based materials for photocatalytic nitrogen fixation in aqueous media, which may be helpful for the design and development of novel nitrogen‐fixing photocatalysts based on MOF materials.
The development of a sensitive and practical electrochemiluminescence (ECL) bioassay relies on the use of ECL signal tags whose signal intensity is high and stable. In this work, strong ECL emission ...was achieved from metal organic framework (MOF) accelerator enriched quantum dots (CdTe), which were applied as an efficient ECL signal tag for trace biomarker detection. It is particularly noteworthy that a novel mechanism to drastically enhance the ECL intensity of CdTe is established because isoreticular metal organic framework-3 (IRMOF-3) with 2-amino terephthalic acid (2-NH2-BDC) as the organic ligand not only allows for loading a large amount of CdTe via the encapsulating effect and internal/external decoration but also functions as a novel coreactant accelerator for promoting the conversion of coreactant S2O8 2– into the sulfate radical anion (SO4 •–), further boosting the ECL emission of CdTe. On the basis of the simple sandwich immunoreaction approach, cardiac troponin-I antigen (cTnI), a kind of biomarker related with myocardial infarction, was chosen as a detection model using an IRMOF-3-enriched CdTe labeled antibody as the signal probe. This immunosensor demonstrated desirable assay performance for cTnI with a wide response range from 1.1 fg mL–1 to 11 ng mL–1 and a very low detection limit (0.46 fg mL–1). This suggested that the IRMOF-3-enriched CdTe nanocomposite strategy can integrate the coreactant accelerator and luminophore to significantly enhance the ECL intensity and stability, providing a direction for promising ECL tag preparation with broad applications.
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