Environmental efficacy of polyethylene microplastics: Enhancing the solidification of CuO nanoparticles and reducing the physiological toxicity to peanuts.

Microplastics and metal-based nanoparticles (NPs) are environmental pollutants that have attracted significant attention. However, there have been relatively few studies on the combined pollution of these substances in the soil-plant system. To investigate the environmental impact and interaction mechanisms of these two pollutants, a pot experiment was conducted to examine the effects of soil exposure on peanut growth. The experiment results revealed that polyethylene (PE) had a minimal effect on peanut growth, while CuO NPs significantly inhibited peanut growth. Peanut biomass decreased by over 50 % in all Cu treatments. The presence of PE significantly impacted the dissolution and absorption of CuO NPs. When 0.5 % PE was present, the dissolution and transformation of CuO NPs were limited, resulting in a total Cu concentration of 458 mg/kg. Conversely, when 5 % PE was present, the dissolution and transformation of CuO NPs were promoted, leading to a DTPA-Cu concentration of 141 mg/kg, the highest level observed. The distribution of trace elements in peanut stems also responded to the differences in Cu concentration. Both pollutants significantly disrupted soil bacteria, with CuO NPs having a more pronounced effect than PE. Throughout the entire growth cycle of peanuts, no chemical adsorption occurred between PE and CuO NPs, and CuO NPs had no significant impact on the aging rate of PE. In summary, this study provides insights into the environmental impact and transport mechanisms of composite pollution involving microplastics and metal-based nanoparticles in the soil-peanut system.

Silver decahedral nanoparticles with uniform and adjustable sizes for surface-enhanced Raman scattering-based thiram residue detection.

Surface-enhanced Raman scattering (SERS) has been widely used as a sensitive molecular spectroscopy technology in food safety detection. Precise morphology control of plasmonic nanoparticles for high sensitivity and high uniformity SERS substrates remains challenging. Herein, silver decahedral nanoparticles (AgDeNPs) with uniform and adjustable sizes were synthesized by a photochemical seed-mediated method and utilized as SERS substrates for pesticide residue detection. The SERS sensitivity was demonstrated by using 4-mercaptobenzoic acid (4-MBA) as a typical model molecule, and the limit of detection (LOD) reached 1.0 × 10-13 M. The pesticide residue detection of thiram in aqueous solution and on fruit peels was successfully realized; the LODs were 1.0 × 10-11 M and 0.96 ng cm-2, respectively, and SERS repeatability was also proved. Overall, size-tunable AgDeNPs show attractive SERS performances and are expected to hold potential application in sensitive food and environmental safety detection.

Modulate the metallic Sb state on ultrathin PdSb-based nanosheets for efficient formic acid electrooxidation.

Incorporation of oxophilic metals into Pd-based nanostructures has shown great potential in small molecule electrooxidation owing to their superior anti-poisoning capability. However, engineering the electronic structure of oxophilic dopants in Pd-based catalysts remains challenging and their impact on electrooxidation reactions is rarely demonstrated. Herein, we have developed a method for synthesizing PdSb-based nanosheets, enabling the incorporation of the Sb element in a predominantly metallic state despite its high oxophilic nature. Moreover, the Pd90Sb7W3 nanosheet serves as an efficient electrocatalyst for the formic acid oxidation reaction (FAOR), and the underlying promotion mechanism is investigated. Among the as-prepared PdSb-based nanosheets, the Pd90Sb7W3 nanosheet exhibits a remarkable 69.03% metallic state of Sb, surpassing the values observed for the Pd86Sb12W2 (33.01%) and Pd83Sb14W3 (25.41%) nanosheets. X-ray photoelectron spectroscopy (XPS) and CO stripping experiments confirm that the Sb metallic state contributes the synergistic effect of their electronic and oxophilic effect, thus leading to an effective electrooxidation removal of CO and significantly enhanced FAOR electrocatalytic activity (1.47 A mg-1; 2.32 mA cm-1) compared with the oxidated state of Sb. This work highlights the importance of modulating the chemical valence state of oxophilic metals to enhance electrocatalytic performance, offering valuable insights for the design of high-performance electrocatalysts for electrooxidation of small molecules.

Nutrient strengthening of winter wheat by foliar ZnO and Fe3O4 NPs: Food safety, quality, elemental distribution and effects on soil bacteria.

With the anticipated application of engineered nanomaterials (ENMs) as foliar fertilizers in agriculture, there is a particular need to accurately assess crop intensification capacity, potential hazards, and effects on the soil environment when ENMs are applied alone or in combination. In this study, the joint analysis of scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) showed that ZnO NPs transformed on the leaf surface or within the leaf, and Fe3O4 NPs were able to translocate from the leaf (~ 25 memu/g) into the stem (~ 4 memu/g), but were unable to enter the grain (below 1 memu/g), guaranteeing food safety. Spray application of ZnO NPs significantly improved grain Zn content of wheat (40.34 mg/kg), whereas Fe3O4 NPs treatment and Zn + Fe NPs treatment did not significantly improve grain Fe content. According to the micro X-ray fluorescence of wheat grains(µ- XRF) and physiological structure in situ analysis showed that ZnO NPs treatment and Fe3O4 NPs treatment could increase the elemental contents of Zn and Fe in the crease tissue and endosperm components, respectively, while antagonism was observed in the grain treated with Zn + Fe NPs. The 16S rRNA gene sequencing results showed that the Fe3O4 NPs treatment had the greatest negative effect on soil bacterial community, followed by Zn + Fe NPs, and ZnO NPs showed some promotion effect. This may be caused by the significantly higher elemental contents of Zn/Fe in the treated roots and soils. This study critically evaluates the application potential and environmental risks of nanomaterials as foliar fertilizers and is instructive for agricultural applications of nanomaterials alone and in combination.

Co-exposure of maize to polyethylene microplastics and ZnO nanoparticles: Impact on growth, fate, and interaction.

Microplastics (MPs), especially polyethylene MPs (PE MPs), which are the primary component of mulch, have attracted increasing attention in recent years. ZnO nanoparticles (NPs), which constitute a metal-based nanomaterial commonly used in agricultural production, co-converge with PE MPs in the soil. However, studies revealing the behavior and fate of ZnO NPs in soil-plant systems in the presence of MPs are limited. In this study, a pot experiment was used to evaluate the effects of maize co-exposure to PE MPs (0.5 % and 5 % w/w) and ZnO NPs (500 mg/kg) on growth, element distribution, speciation, and adsorption mechanism. The results demonstrate that individual exposure to PE MPs posed no significant toxicity; however, it significantly decreased maize grain yield (essentially 0). ZnO NP-exposure treatments significantly increased the Zn concentration and distribution intensity in maize tissues. Among them, the Zn concentration in the maize root exceeded 200 mg/kg, compared with 40 mg/kg in the grain. Moreover, the Zn concentrations in various tissues decreased in the following order: stem, leaf, cob, bract, and grain. Reassuringly, ZnO NPs still could not be transported to the maize stem under co-exposure to PE MPs. ZnO NPs had been biotransformed (64 % of the Zn was associated with histidine, with the remainder being associated with P [phytate] and cysteine) in maize stem. This study provides new insights into the plant physiological risks of PE MP and ZnO NP co-exposure in the soil-plant system and assesses the fate of ZnO NPs.

Uptake, transformation, and environmental impact of zinc oxide nanoparticles in a soil-wheat system.

Zinc oxide nanoparticles (ZnO-NPs) are metal-based nanomaterials, but their long-term effects on plant growth and the soil environment in the field remain unclear with most previous studies using short-term laboratory and glasshouse studies. In this study, we used a field experiment to examine the long-term effects of ZnO-NPs in a soil-wheat (Triticum aestivum) system. It was found that although ZnO-NPs had no significant effect on either yield or the concentration of other nutrients within the grain, the application of ZnO-NPs significantly increased Zn concentrations. Indeed, for grain, the application of ZnO-NPs to both the soil and foliage (SFZnO) (average of 33.1 mg/kg) significantly increased grain Zn concentrations compared to the the control treatment (21.7 mg/kg). Using in situ analyses, nutrients were found to accumulate primarily in the crease tissue and the aleurone layer of the grain, regardless of treatment. Specifically, the concentration of Zn in the aleurone layer for the SFZnO treatment was 2-3 times higher than that in the control, being >300 mg/kg, whilst the Zn concentration in the crease tissue was ca. 600 mg/kg in the SFZnO treatment, being two times higher than for the control. Although the application of ZnO-NPs increased the total Zn within the grain, it did not accumulate within the grain as ZnO-NPs with this being important for food safety, but rather mainly as Zn-phytate, with the remainder of the Zn complexed with either cysteine or phosphate. Finally, we also observed that ZnO-NPs caused fewer changes to the soil bacterial community structure and that it had no nano-specific toxicity.

Effects of short-term soil exposure of different doses of ZnO nanoparticles on the soil environment and the growth and nitrogen fixation of alfalfa.

The extensive application of nanomaterials has increased their levels in soil environments. Therefore, clarifying the process of environmental migration is important for environmental safety and human health. In this study, alfalfa was used to determine the effects of different doses of ZnO nanoparticles (NPs) on the growth of alfalfa and the soil environment. Results showed that the alfalfa biomass was inversely proportional to the exposure concentration of ZnO NPs. The Zn concentration in the alfalfa tissue and the exposure dose presented a significant positive correlation. A high concentration of ZnO NPs decreased the nitrogen-fixing area of root nodules while the number of bacteroids and root nodules, which in turn affected the nitrogen-fixing ability of alfalfa. At the same time, it caused different degrees of damage to the root nodules and root tip cells of alfalfa. A high dose of ZnO NPs decreased the relative abundance and diversity of the soil microorganisms. Therefore, short-term and high-dose exposure of ZnO NPs causes multiple toxicities in plants and soil environments.

Ectopic Expression of Executor Gene Xa23 Enhances Resistance to Both Bacterial and Fungal Diseases in Rice.

Bacterial blight (BB) and bacterial leaf streak (BLS), caused by phytopathogenic bacteria Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively, are the most serious bacterial diseases of rice, while blast, caused by Magnaporthe oryzae (M. oryzae), is the most devastating fungal disease in rice. Generating broad-spectrum resistance to these diseases is one of the key approaches for the sustainable production of rice. Executor (E) genes are a unique type of plant resistance (R) genes, which can specifically trap transcription activator-like effectors (TALEs) of pathogens and trigger an intense defense reaction characterized by a hypersensitive response in the host. This strong resistance is a result of programed cell death induced by the E gene expression that is only activated upon the binding of a TALE to the effector-binding element (EBE) located in the E gene promoter during the pathogen infection. Our previous studies revealed that the E gene Xa23 has the broadest and highest resistance to BB. To investigate whether the Xa23-mediated resistance is efficient against Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of BLS, we generated a new version of Xa23, designated as Xa23p1.0, to specifically trap the conserved TALEs from multiple Xoc strains. The results showed that the Xa23p1.0 confers broad resistance against both BB and BLS in rice. Moreover, our further experiment on the Xa23p1.0 transgenic plants firstly demonstrated that the E-gene-mediated defensive reaction is also effective against M. oryzae, the causal agent of the most devastating fungal disease in rice. Our current work provides a new strategy to exploit the full potential of the E-gene-mediated disease resistance in rice.

Designer Gold-Framed Palladium Nanocubes for Plasmon-Enhanced Electrocatalytic Oxidation of Ethanol.

Surface plasmon of coinage metal nanostructures has been employed as a powerful route in boosting the performances in heterogenous catalysis. Development of efficient plasmonic nanocatalysts with high catalytic performance and efficient light harvesting properties is of vital importance. Herein, we rationally designed and synthesized a plasmonic nanocatalyst composed of Au-framed Pd nanocubes by an Ag(I)-assisted seed-mediated growth method. In the synthesis, the incorporation of Ag(I) suppresses the reduction of Au on the {100} surface of cubic Pd seeds and leads to the formation of Au nanoframes on the Pd nanocubes. The unique Au-framed Pd nanocubes can integrate the superior electrocatalytic of Pd and the outstanding plasmonic properties of Au. Thus, these nanostructures were employed as plasmonic nanocatalysts for plasmon-enhanced electrocatalytic oxidation of ethanol with improved stability.

Interaction of different-sized ZnO nanoparticles with maize (Zea mays): Accumulation, biotransformation and phytotoxicity.

This study aimed to investigate the biotransformation of ZnO nanoparticles (NPs) in maize grown in hydroponics for ecotoxicity assessment. Maize seedlings grown for 14 days were exposed to a solution of 9 nm ZnO NPs, 40 nm ZnO NPs, and ZnSO4 at a Zn concentration of 300 mg L-1 for 1, 3, and 7 days, respectively. The results of in-situ Zn distribution in maize (Zea mays) showed that 9 nm ZnO NPs could quickly enter the roots of maize and reach the center column transport system of the stem. The results of transmission electron microscopy combined with energy dispersive X-ray spectroscopy revealed that ZnO NPs were accumulated in the vacuoles of the roots, and then transformed and transported through vesicles. Simulated studies showed that low pH (5.6) played a critical role in the transformation of ZnO NPs, and organic acids (Kf = 1011.4) could promote particle dissolution. Visual MINTEQ software simulated the species of Zn after the entry of ZnO NPs or Zn2+ into plants and found that the species of Zn was mainly Zn2+ when the Zn content of plants reached 200-300 ppm. Considering that the lowest Zn content of the roots in treatments was 1920 mg kg-1, combination of the result analysis of root effects showed that the toxicity of roots in most treatments had a direct relationship with Zn2+. However, treatment with 9 nm ZnO NPs exhibited significantly higher toxicity than ZnSO4 treatment on day 1 when the Zn2+ concentration difference was not significant, which was mainly due to the large amount of ZnO NPs deposited in the roots. To the authors' knowledge, this study was the first to confirm the process of biotransformation and explore the factors affecting the toxicity of ZnO NPs in depth.

Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain.

Zinc (Zn) deficiency is an important problem worldwide, adversely impacting human health. Using a field trial in China, we compared the foliar application of both ZnO nanoparticles (ZnO-NPs) and ZnSO4 on winter wheat (Triticum aestivum L.) for increasing the Zn concentration within the grain. We also used synchrotron-based X-ray fluorescence microscopy and laser ablation inductively coupled plasma mass spectrometry to examine the distribution of Zn within the grain. We found that ZnO-NPs increase the Zn concentration in the wheat grain, increasing from 18 mg·kg-1 in the control up to 40 mg·kg-1 when the ZnO-NPs were applied four times. These grain Zn concentrations in the ZnO-NP-treated grains are similar to those recommended for human consumption. However, the ZnO-NPs were similar in their effectiveness to ZnSO4. When examining trace element distribution in the grain, the trace elements were found to accumulate primarily in the aleurone layer and the crease region across all treatments. Importantly, Zn concentrations in the grain endosperm increased by nearly 30-fold relative to the control, with markedly increasing Zn concentrations within the edible portion. These results demonstrate that ZnO-NPs are a suitable fertilizer for increasing Zn within wheat grain and can potentially be used to improve human nutrition.

RNA-Seq analysis of gene expression changes triggered by Xanthomonas oryzae pv. oryzae in a susceptible rice genotype.

BACKGROUND: Xanthomonas oryzae pv. oryzae (Xoo) is a destructive disease in most of the rice growing regions worldwide. Xoo injects the transcriptional activator-like (TAL) effector protein into the host cell to induce the susceptibility (S) gene(s) for spreading the disease. In the current study, a susceptible rice genotype, JG30, was inoculated with wild Xoo strain PXO99A and its mutant PH without any TAL effector, to retrieve the differentially expressed genes (DEGs) having a role in susceptibility. RESULTS: RNA-Seq data analysis showed that 1143 genes were significantly differentially expressed (p-value ≤0.05) at 12, 24, 36 and 48 h post inoculation (hpi). Expression patterns, evaluated by quantitative real-time PCR (qRT-PCR), of randomly selected eight genes were similar to the RNA-Seq data. KEGG pathway classified the DEGs into photosynthesis and biosynthesis of phenylpropanoid pathway. Gene ontology (GO) analysis categorized the DEGs into the biological pathway, cellular component, and molecular function. We identified 43 differentially expressed transcription factors (TFs) belonging to different families. Also, clusters of the DEGs representing kinase and peroxidase responsive genes were retrieved. MapMan pathway analysis representing the expression pattern of genes expressed highly in biotic stress and metabolic pathways after PXO99A infection relative to PH. CONCLUSIONS: DEGs were identified in susceptible rice genotype inoculated with PXO99A relative to mutant strain PH. The identified 1143 DEGs were predicted to be included in the different biological processes, signaling mechanism and metabolic pathways. The Jasmonic acid (JA) responsive genes were identified to be downregulated in PXO99A infected leaves. This study would be useful for the researchers to reveal the potential functions of genes involved in the rice susceptibility to PXO99A infection.

Improvement of biochar and bacterial powder addition on gaseous emission and bacterial community in pig manure compost.

Effect of bamboo biochar (BC) combined with two bacterial powders (B) on gaseous emission and variety of bacterial community during pig manure (PM) composting was investigated. The results showed that treatments of BC, BC + B1 and BC + B2 can reduce peak gaseous emission by 54%, 80% and 69% for CH4, respectively, while 37%, 45% and 45% for N2O, respectively, and 13%, 19% and 26% for NH3, respectively. The evolution of the bacterial community quantified with 16S rDNA analysis showed that in the thermophile stage, total relative abundance percentage of bacterial phyla of Firmicutes and Proteobacteria reached 97%, 97%, 93% and 96% for CK, BC, BC + B1 and BC + B2, respectively. Effects of BC on the compost bacterial community variation analysis proved bacterial activity in the thermophile stage was controlled by the content of dissolved organic carbon and temperature of the compost mixture, while electrical conductivity and total kjeldahl nitrogen also influenced compost maturity stage.

Using Synchrotron-Based Approaches To Examine the Foliar Application of ZnSO4 and ZnO Nanoparticles for Field-Grown Winter Wheat.

The effects of foliar-applied ZnO nanoparticles (ZnO NPs) and ZnSO4 on the winter wheat ( Triticum aestivum L.) grain yield and grain quality were studied under field conditions, with the distribution and speciation of Zn within the grain examined using synchrotron-based X-ray fluorescence microscopy and X-ray absorption spectroscopy. Although neither of the two Zn compounds improved the grain yield or quality, both increased the grain Zn concentration (average increments were 5 and 10 mg/kg for ZnSO4 and ZnO NP treatments, respectively). Across all treatments, this Zn was mainly located within the aleurone layer and crease of the grain, although the application of ZnO NPs also slightly increased Zn within the endosperm. This Zn within the grain was found to be present as Zn phosphate, regardless of the form in which Zn was applied. These results indicate that the foliar application of ZnO NPs appears to be a promising approach for Zn biofortification, as required to improve human health.