Locally Enhanced Flow and Electric Fields Through a Tip Effect for Efficient Flow-Electrode Capacitive Deionization.

Low-electrode capacitive deionization (FCDI) is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters. However, it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes, both restricted by the current collectors. Herein, a new tip-array current collector (designated as T-CC) was developed to replace the conventional planar current collectors, which intensifies both the charge transfer and ion transport significantly. The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy, which revealed the reduction of ion transport barrier, charge transport barrier and internal resistance. With the voltage increased from 1.0 to 1.5 and 2.0 V, the T-CC-based FCDI system (T-FCDI) exhibited average salt removal rates (ASRR) of 0.18, 0.50, and 0.89 µmol cm-2 min-1, respectively, which are 1.82, 2.65, and 2.48 folds higher than that of the conventional serpentine current collectors, and 1.48, 1.67, and 1.49 folds higher than that of the planar current collectors. Meanwhile, with the solid content in flow electrodes increased from 1 to 5 wt%, the ASRR for T-FCDI increased from 0.29 to 0.50 µmol cm-2 min-1, which are 1.70 and 1.67 folds higher than that of the planar current collectors. Additionally, a salt removal efficiency of 99.89% was achieved with T-FCDI and the charge efficiency remained above 95% after 24 h of operation, thus showing its superior long-term stability.

The Accurate and Exclusive Quantification of Somatic Cells in Raw Milk with an OPD-Cu2+ System-Based Colorimetric Method.

The somatic cell count (SCC) refers to the number of somatic cells present in each milliliter of raw milk and serves as a crucial indicator of dairy cow udder health and raw milk quality. Traditional SCC detection methods are often time-consuming, expensive, and susceptible to bacterial interference, rendering them unsuitable for the rapid and unbiased assessment of raw milk quality. Consequently, there is an urgent need for a low-cost, accurate, and user-friendly SCC quantification method. Here, a method based on an OPD-Cu2+ system for SCC quantification was developed. It was found that OPD oxidation signals exhibited a linear correlation with SCC. Following optimization, the detection system was established with a Cu2+ concentration of 25 µM, an OPD concentration of 2 mM, and an incubation time of 15 min. Furthermore, the method demonstrated significant resistance to bacterial interference, though it produced weaker signals in response to bacteria. The somatic cell recovery rate in milk after pretreatment was 88.9%, and SCC was quantified accurately within 45 min, with a linear range of 104-106 cells/mL. In summary, the method developed is cost-effective, straightforward, and facilitates precise somatic cell quantification, offering significant practical value and a new approach for SCC detection in raw milk.

Drying-rewetting alters arsenic ecotoxicity: From the perspective of enzyme-based functional diversity.

Drying-rewetting (DW) cycles can significantly influence soil properties and microbial community composition, leading to direct or indirect changes in arsenic (As) toxicity, which inturn affects soil ecological functions. Despite this, there has been insufficient focus on accurately evaluating As ecotoxicity and its impact on soil ecological function under DW conditions. This study seeks to address this gap by examining the effects of DW on As toxicity and the characteristics of soil ecological function, specifically from the perspective of enzyme-based functional diversity. Our results reveal that compared to constant moisture conditions, DW treatment significantly increased the toxicity of As on alkaline phosphatase and ß-glucosidase, with maximum inhibition rates observed at 46.29% and 21.54%, respectively. Conversely, for other tested enzymes including invertase, fluorescein diacetate hydrolase, and dehydrogenase, DW treatment decreased As toxicity, possibly be due to the different stability of these enzymes under varying soil moisture conditions. From an enzyme functional diversity perspective, DW treatment reduced the As toxicity, as evidenced by the reduced inhibition rates and a lower coefficient of variation. In conclusion, DW appears to enhance soil functional resilience against arsenic pollution. These findings contribute to a better understanding of changes in ecological functions in heavy metal-contaminated soils under dynamic environmental conditions, offering insights for improved monitoring and mitigation strategies for metalloids toxicity in natural environments.

Soil urease functional stability to Hg pollution: An ecotoxicological perspective.

Mercury (Hg) is a persistent soil pollutant, and its toxicity can be evaluated using soil enzyme indicators. However, a thorough understanding of how the enzyme resists and remains resilient to Hg stress is essential, as it significantly impacts the accuracy of toxicity assessments. Therefore, it is worthwhile to understand the functional stability of urease in soil under Hg pollution. This study compares the effects of Hg at different concentrations and exposure times on soil urease. Results indicate that soil urease activity was enhanced in the first two hours under low levels of Hg pollution, decreased after six hours of acute Hg pollution, and reached its maximum reduction in 24 hours. The urease in fluvo-aquic soil, with higher soil organic matter showed higher resistance to Hg acute pollution than that in red soil. Over a longer aging process, soil urease activity gradually recovered with time. Hormesis effects were observed in red soil under high Hg stress after 30 days, showing the strong resilience of urease enzyme function to Hg pollution. The ecological dose, ED10, (the Hg concentration causing a 10% reduction in soil urease activity) ranged from 0.09 to 0.59 mg kg-1 under short-term exposure, and was lower than that under a longer aging process (0.28 to 2.71 mg kg-1). Further, aging reduced the Hg ecotoxicity due to decreased Hg availability and the resilience of soil urease activity. This indicates that the risk of Hg pollution estimated by soil urease as an indicator depends on exposure time and enzyme stability. These factors need consideration in heavy metal pollution assessments using soil enzymes.

Rapid and accurate quantification of viable Bifidobacterium cells in milk powder with a propidium monoazide-antibiotic fluorescence in situ hybridization-flow cytometry method.

Due to its beneficial effects on human health, Bifidobacterium is commonly added to milk powder. Accurate quantification of viable Bifidobacterium is essential for assessing the therapeutic efficacy of milk powder. In this study, we introduced a novel propidium monoazide (PMA)-antibiotic fluorescence in situ hybridization (AFISH)-flow cytometry (FC) method to rapidly and accurately quantify viable Bifidobacterium cells in milk powder. Briefly, Bifidobacterium cells were treated with chloramphenicol (CM) to increase their rRNA content, followed by staining with RNA-binding oligonucleotide probes, based on the AFISH technique. Then, the DNA-binding dye PMA was used to differentiate between viable and nonviable cells. The PMA-AFISH-FC method, including sample pretreatment, CM treatment, dual staining, and FC analysis, required approximately 2 h and was found to be better than the current methods. This is the first study to implement FC combined with PMA and an oligonucleotide probe for detecting Bifidobacterium.

Potential effects of soil petroleum contamination on decomposition of Artemisia annua plant litter.

The accumulation of petroleum contaminants in phytoremediating plants can significantly impact the decomposition of their litter. However, the mechanisms underlying these effects and the potential influence of the contaminant concentration remain unclear. In this study, litter from Artemisia annua plants grown in soil with varying concentrations of petroleum (0, 15, 30, and 45 g kg-1) was collected. The litter samples were then inoculated with soil microorganisms and subjected to an indoor simulation of decomposition under controlled temperature and humidity conditions. Changes in the chemical properties, activities of decomposition-related enzymes in the litter, and decomposition rates were measured. Additionally, structural equation modeling was employed to analyze the mechanism through which soil petroleum contamination affects litter decomposition. The findings revealed several key points: (1) increasing soil petroleum contamination tended to reduce the concentration of carbon and nitrogen in litter while increasing those of lignin and total petroleum hydrocarbons (TPH). (2) Soil petroleum contamination tended to increase the activities of both total lignocellulases and total nutrient cycling-related enzymes in litter. (3) Soil petroleum contamination might indirectly inhibit the activity of lignocellulases by increasing the concentration of lignin and TPH in litter. However, it might also directly accelerate the activity of these enzymes, resulting in contradictory effects on litter decomposition. (4) Finally, A. annua litter produced in soil contaminated with 15 and 30 g kg-1 of petroleum exhibited significantly lower decomposition rates than that from uncontaminated soil.

Arsenic stress on soil microbial nutrient metabolism interpreted by microbial utilization of dissolved organic carbon.

In a 120-day microcosm incubation experiment, we investigated the impact of arsenic contamination on soil microbial nutrient metabolism, focusing on carbon cycling processes. Our study encompassed soil basal respiration, key enzyme activities (particularly, ß-1,4-N-acetylglucosaminidase and phosphatases), microbial biomass, and community structure. Results revealed a substantial increase (1.21-2.81 times) in ß-1,4-N-acetylglucosaminidase activities under arsenic stress, accompanied by a significant decrease (9.86%-45.20%) in phosphatase activities (sum of acid and alkaline phosphatases). Enzymatic stoichiometry analysis demonstrated the mitigation of microbial C and P requirements in response to arsenic stress. The addition of C-sources alleviated microbial C requirements but exacerbated P requirements, with the interference amplitude increasing with the complexity of the C-source. Network analysis unveiled altered microbial nutrient requirements and an increased resistance process of microbes under arsenic stress. Microbial carbon use efficiency (CUE) and basal respiration significantly increased (1.17-1.59 and 1.18-3.56 times, respectively) under heavy arsenic stress (500 mg kg-1). Arsenic stress influenced the relative abundances of microbial taxa, with Gemmatimonadota increasing (5.5-50.5%) and Bacteroidota/ Nitrospirota decreasing (31.4-47.9% and 31.2-63.7%). Application of C-sources enhanced microbial resistance to arsenic, promoting cohesion among microorganisms. These findings deepen our understanding of microbial nutrient dynamics in arsenic-contaminated areas, which is crucial for developing enzyme-based toxicity assessment systems for soil arsenic contamination.

Rapid and Accurate Quantification of Viable Lactobacillus Cells in Infant Formula by Flow Cytometry Combined with Propidium Monoazide and Signal-Enhanced Fluorescence In Situ Hybridization.

Lactobacillus is an important member of the probiotic bacterial family for regulating human intestinal microflora and preserving its normalcy, and it has been widely used in infant formula. An appropriate and feasible method to quantify viable Lactobacilli cells is urgently required to evaluate the quality of probiotic-fortified infant formula. This study presents a rapid and accurate method to count viable Lactobacilli cells in infant formula using flow cytometry (FCM). First, Lactobacillus cells were specifically and rapidly stained by oligonucleotide probes based on a signal-enhanced fluorescence in situ hybridization (SEFISH) technique. A DNA-binding fluorescent probe, propidium monoazide (PMA), was then used to accurately recognize viable Lactobacillus cells. The entire process of this newly developed PMA-SEFISH-FCM method was accomplished within 2.5 h, which included pretreatment, dual staining, and FCM analysis; thus, this method showed considerably shorter time-to-results than other rapid methods. This method also demonstrated a good linear correlation (R2 = 0.9994) with the traditional plate-based method with a bacterial recovery rate of 91.24%. To the best of our knowledge, the present study is the first report of FCM combined with PMA and FISH for the specific detection of viable bacterial cells.

A meta-analysis of the efficacy and safety of first-line chemotherapeutic agents for osteosarcoma.

BACKGROUND: Osteosarcoma is a pleomorphic cancer that frequently affects children and teenagers. Although several chemotherapy regimens have been utilized for many years, the best therapeutic option for the treatment of osteosarcoma has not yet been determined. OBJECTIVES: This meta-analysis was designed to assess the clinical efficacy of a high-dose methotrexate, doxorubicin and cisplatin (MAP) regimen and compare its survival outcomes with those of other chemotherapy strategies in patients diagnosed with osteosarcoma. MATERIAL AND METHODS: We systematically searched databases, namely Embase, the Cochrane Library and PubMed, up to August 2022, for relevant studies investigating the impact of the MAP chemotherapy protocol on survival among patients with osteosarcoma. The odds ratio (OR) pooled estimates and their 95% confidence intervals (95% CIs) were calculated. RESULTS: Twelve studies including 4102 patients were eligible for analysis in this study. The estimated pooled ORs of the 3-year overall survival (OS) and event-free survival (EFS) were OR = 1.08 (95% CI: 0.72-1.62, p = 0.70) and OR = 1.04 (95% CI: 0.81-1.32, p = 0.78, respectively). The 5-year OS and EFS were OR = 0.87 (95% CI: 0.62-1.23, p = 0.42) and OR = 1.13 (95% CI: 0.76-1.68, p = 0.54), respectively, with no statistical differences. The subgroup analysis of MAP compared to a 2-drug regimen (doxorubicin and cisplatin) revealed a significant difference between the 2 chemotherapy strategy groups in 3-year OS rates (OR = 0.72 (95% CI: 0.56-0.92, p = 0.009)) and 5-year EFS rates (OR = 0.57 (95% CI: 0.43-0.76, p < 0.001)). CONCLUSION: The MAP chemotherapy strategy for osteosarcoma showed superiority over other regimens, especially over the 2-drug regimen (doxorubicin/cisplatin), in terms of better prognosis and safety.

Non-precious metal-based heterostructure catalysts for hydrogen evolution reaction: mechanisms, design principles, and future prospects.

As a highly promising clean energy source to replace fossil fuels in the 21st century, hydrogen energy has garnered considerable attention, with water electrolysis emerging as a key hydrogen production technology. The development of highly active and stable non-precious metal-based catalysts for the hydrogen evolution reaction (HER) is crucial for achieving efficient and low-cost hydrogen production through electrolysis. Recently, heterostructure composite catalysts comprising two or more non-precious metals have demonstrated outstanding catalytic performance. First, we introduced the basic mechanism of the HER and, based on the reported HER theory, discussed the essence of constructing heterostructures to improve the catalytic activity of non-noble metal-based catalysts, that is, the coupling effect between components effectively regulates the electronic structure and the position of d-band centers. Then three catalytic effects of non-precious metal-based heterogeneous catalysts are described: synergistic effect, electron transfer effect and support effect. Lastly, we emphasized the potential of non-precious metal-based heterogeneous catalysts to replace precious metal-based catalysts, and summarized the future prospects and challenges.

3D Imprinting of Voxel-Level Structural Colors in Lithium Niobate Crystal.

Advanced coloration methods are of pivotal importance in science, technology, and engineering. However, 3D structural colors that are critical for emerging multidimensional information representation and recording are rarely achievable. Here, a facile voxel-level programmable 3D structural coloration in the bulk lithium niobate (LiNbO3 ) crystal is reported. This is achieved by engineering wavelength-selective interference between ordinary (O) and extraordinary (E) light in the crystal matrix. To induce effective phase contrast between O and E light for establishing the highly localized interference across the visible band, the presence of a pulse-internal-coupling effect is revealed in the single-pulse ultrafast laser-crystal interaction and an ultrafast-laser-induced micro-amorphization (MA) strategy is thus developed to manipulate local matrix structure. Consequently, micro-nanoscale colorful voxels can be fast inscribed into any spatial position of the crystal matrix in one step. It is demonstrated that the colors can be flexibly manipulated and quickly extracted in 3D space. Multidimensional MA-color data storage with large capacity, high writing and readout speed, long lifetime, and excellent stability under harsh conditions is achieved. The present principle enables multifunctional 3D structural coloration devices inside high-refractive-index transparent dielectrics and can serve as a general platform to innovate next-generation information optics.

Ecotoxicity of soil Pb pollution reflected by soil ß-glucosidase: Comparison of extracellular and intracellular enzyme pool.

Lead (Pb) is a major environmental pollutant that threatens the soil environment and human health. Monitoring and assessing Pb toxicity on soil health are of paramount importance to the public. To use soil enzymes as biological indicators of Pb contamination, herein, the responses of soil ß-glucosidase (BG) in different pools of soil (total, intracellular and extracellular enzyme) to Pb contamination were investigated. The results indicated that the intra-BG (intracellular BG) and extra-BG (extracellular BG) responded differently to Pb contamination. While the addition of Pb caused a significant inhibition of the intra-BG activities, the extra-BG activities were only slightly inhibited. Pb showed a non-competitive inhibition to extra-BG, while both non-competitive and uncompetitive inhibition were observed for intra-BG in the tested soils. The dose-response modeling was used to calculate ecological dose ED10, which represents the concentration of Pb pollutant that causes a 10 % reduction in Vmax, to express the ecological consequences of Pb contamination. A positive correlation was found between ecological dose ED10 values of intra-BG and soil total nitrogen (p < 0.05), which suggests soil properties may influence Pb toxicity to soil BG. Based on the differences in ED10 and inhibition rate among different enzyme pools, this study suggests that the intra-BG is more sensitive for Pb contamination assessment. From this, we propose that intra-BG should be considered when evaluating Pb contamination using soil enzymes as indicators.

Post-synthetic modification (PSM) of MOFs with an ionic polymer for efficient adsorptive removal of methylene blue from water.

UiO-66-NH2 was functionalized with an ionic polymer poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) through a post-synthetic modification (PSM) strategy. Due to the excellent dispersibility in water and the existence of abundant active binding sites, the obtained UiO-66-PAMPS shows significantly improved adsorption capability toward methylene blue (MB) in aqueous solution.

Engineering sodium alginate-SiO2 composite beads for efficient removal of methylene blue from water.

The lack of sufficient active binding sites in commonly reported sodium alginate (SA)-based porous beads hampers their performances in adsorption of water contaminants. To address this problem, porous SA-SiO2 beads functionalized with poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) are reported in this work. Due to the porous properties and the existence of abundant sulfonate groups, the obtained composite material SA-SiO2-PAMPS shows excellent adsorption capacity toward cationic dye methylene blue (MB). The adsorption kinetic and adsorption isotherm studies reveal that the adsorption process fits closely to pseudo-second-order kinetic model and Langmuir isotherm model, respectively, suggesting the existence of chemical adsorption and monolayer adsorption behavior. The maximum adsorption capacity obtained from Langmuir model is found to be 427.36, 495.05, and 564.97 mg/g under 25, 35, and 45 °C, respectively. The calculated thermodynamic parameters indicate that MB adsorption on SA-SiO2-PAMPS is spontaneous and endothermic.

Using soil enzyme Vmax as an indicator to evaluate the ecotoxicity of lower-ring polycyclic aromatic hydrocarbons in soil: Evidence from fluorescein diacetate hydrolase kinetics.

Fluorescein diacetate hydrolase (FDA hydrolase) is a reliable biochemical biomarker of changes in soil microbial activity and quality. However, the effect and mechanism of lower-ring polycyclic aromatic hydrocarbons (PAHs) on soil FDA hydrolase are still unclear. In this work, we investigated the effects of two typical lower-ring PAHs, naphthalene (Nap) and anthracene (Ant), on the activity and kinetic characteristics of FDA hydrolases in six soils differing in their properties. Results demonstrated that the two PAHs severely inhibited the activities of the FDA hydrolase. The values of Vmax and Km dropped by 28.72-81.24 % and 35.84-74.47 % at the highest dose of Nap, respectively, indicating an uncompetitive inhibitory mechanism. Under Ant stress, the values of Vmax decreased by 38.25-84.99 %, and the Km exhibited two forms, unchanged and decreased (74.00-91.61 %), indicating uncompetitive and noncompetitive inhibition. The inhibition constant (Ki) of the Nap and Ant ranged from 0.192 to 1.051 and 0.018 to 0.087 mM, respectively. The lower Ki of Ant compared to Nap indicated a higher affinity for enzyme-substrate complex, resulting in higher toxicity of Ant than Nap to soil FDA hydrolase. The inhibitory effect of Nap and Ant on soil FDA hydrolase was mainly affected by soil organic matter (SOM). SOM influenced the affinity of PAHs with enzyme-substrate complex, which resulted in a difference in PAHs toxicity to soil FDA hydrolase. The enzyme kinetic Vmax was a more sensitive indicator than enzyme activity to evaluate the ecological risk of PAHs. This research offers a strong theoretical foundation for quality control and risk evaluation of PAH-contaminated soils through a soil enzyme-based approach.

Transcriptomic and metabolomic changes in lettuce triggered by microplastics-stress.

Microplastics (MPs) are a global threat to the environment, and plant uptake of MP particles (≤0.2 µm) is a particular cause for concern. However, physiological and molecular mechanisms underlying MP-induced growth inhibition need to be clarified. Towards this goal, we conducted a hydroponic experiment to investigate the accumulation of MPs, changes in physiology, gene expression, and metabolites in lettuce from a series of concentrations of fluorescence-labelled polystyrene MPs (0, 10, 20, 30, 40, 50 mg L-1, ∼0.2 µm). Our results showed that MPs accumulated in the lettuce root tips and leaf veins, resulting in the hypertonic injury of lettuce, and the down-regulation of genes related to ion homeostasis. Stress-related genes were up-regulated, and sphingolipid metabolism increased in response to MP additions, causing increased biosynthesis of ascorbic acid, terpenoid, and flavonoids in root exudates. Our findings provide a molecular-scale perspective on the response of leafy vegetables to MP-stress at a range of concentrations. This enables more comprehensive evaluation of the risks of MPs to human health and the ecological environment.

Manure- and straw-derived biochars reduce the ecological risk of PBDE and promote nitrogen cycling by shaping microbiomes in PBDE-contaminated soil.

Pyrolysis of agricultural waste into biochar for soil remediation is a useful solid waste management strategy. However, it is still unclear how different agricultural feedstocks affect the properties of biochars and their effectiveness in remediation of PBDE-contaminated soil. In this study, we systematically investigated dynamic alterations of soil properties, microbial communities, and PBDE dissipation and bioavailability induced by the application of biochars from manure (MBC) and straw (SBC) to PBDE-contaminated soil. The results showed that soil properties, microbial community structure, and diversity changed differently with the incorporation of the two biochars. MBC had a larger surface area (17.4 m2/g) and a higher nutrient content (45.1% ash content), making it more suitable for use as a soil additive to improve soil quality and nutrient conditions, as well as to stimulate microbial growth. SBC showed higher adsorption capacity for 2,2',4,4'-Tetrabromodiphenyl Ether (BDE-47) (26.73 ± 0.65 mg/g), thus lowering the bioavailability and ecological risk of BDE-47 in soil. BDE-47 was stepwise debrominated into lower brominated PBDE by PBDE-degrading bacteria. MBC accelerated the debromination of BDE-47 (10.1%) by promoting PBDE-degrading microorganisms, while this was inhibited by SBC (3.5%) due to strong adsorption of BDE-47. In addition, we found that both types of biochar favored Nitrospirae bacteria and promoted N cycling. Overall, biochars from manure and straw can positively shape soil microbial communities differently by altering soil properties, soil fertility and nutrient availability, and the fate and the effects of contaminants, which ultimately led to a difference in the potential of biochars for their use in soil remediation.

Silencing P25, HC-Pro and Brp1 of Potato Virus (Viroid) Using Artificial microRNA Confers Resistance to PVX, PVY and PSTVd in Transgenic Potato.

Virus infection is the key constraint to potato cultivation worldwide. Especially, coinfection by multiple viruses could exacerbate the yield loss. Transgenic plants expressing artificial microRNAs (amiRNAs) have been shown to confer specific resistance to viruses. In this study, three amiRNAs containing Arabidopsis miR159 as a backbone, expressing genes targeting P25, HC-Pro and Brp1 of potato virus X (PVX), potato virus Y (PVY) and potato spindle tuber viroid (PSTVd), were constructed. amiR-159P25, amiR-159HCPro and amiR-159Brp1 were cloned into the plant expression vector pCAMBIA1301 with a CaMV35S promoter, producing the p1301-pre-amiRP25-HCPro-Brp1 vector. Twenty-three transgenic plants (Solanum tuberosum cv. 'Youjin') were obtained by Agrobacterium tumefaciens-mediated transformation, and ten PCR-positive transplants were chosen for further analysis. Quantitative real-time PCR results indicated that 10 transgenic plants could express amiRNAs successfully. Southern blotting hybridization proved that amiR-159P25-HCPro-Brp1 had integrated into potato genome in transgenic lines. Viral (viroid) challenge assays revealed that these transgenic plants demonstrated resistance against PVX, PVY and PSTVd coinfection simultaneously, whereas the untransformed controls developed severe symptoms. This study demonstrates a novel amiRNA-based mechanism that may have the potential to develop multiple viral resistance strategies in potato.

Ecotoxicity of parathion during its dissipation mirrored by soil enzyme activity, microbial biomass and basal respiration.

The application of parathion (PTH) in agriculture can result in its entry into the soil and threaten the soil environment. Monitoring the PTH residues and assessing toxicity on soil health are of paramount importance to the public. Herein, the dissipation of PTH and concomitant influence on microbial activities [FDA hydrolase (FDA‒H), microbial biomass carbon (MBC) and basal respiration (BR)] in coastal solonchaks were investigated. Results showed that the dissipation of PTH in tested soil declined linearly, and the half-lives varied from 5.6 to 56.8 days, depending on pollutant concentrations. The FDA‒H activity and MBC were negatively affected by PTH pollution and exhibited a significantly positive correlation. Two‒way ANOVA analysis demonstrated that microbial activities were affected not only by PTH dose and incubation time but also by their interactions. The integrated biomarker response (IBR/n) index values on day 120 were between 1.02 and 2.89, larger than those on day 1 during PTH dissipation. This implied that the soil quality did not recover though there was no PTH residue in the soil at the end of the experiment. These findings suggested that microbial activities integrated with IBR/n index could elucidate the hazardous impacts of PTH dissipation on biochemical cycling and microorganisms in soil.

Evaluation of volume-based flow cytometry as a potential primary method for quantification of bacterial reference material.

Bacterial reference materials (RMs) play a crucial role in many analytical processes of microbiological detection. Currently, bacteria are typically counted using the traditional plate-based approach, which results in a higher uncertainty of bacterial RMs unfortunately. Therefore, novel methods are urgently required for the value assignment of RMs in the field of microbiology to derive measurement traceability and accuracy. A potential primary method for microbiological quantification based on flow cytometry (FCM) is described in this study using Escherichia coli O157 (E. coli O157) as an example. The proposed method was applied to determine the number of viable E. coli O157 cells in the RMs with a result of (5.48 ± 0.27) × 108 cells mL-1, which was in good agreement with the result obtained using the plate-based method (En = 0.47). Additionally, this method could be entirely described and understood by equations, and provides formal traceability to the SI for counts of viable bacterial cells, while the associated relative expanded uncertainty (4.93%, k = 2) was significantly lower in comparison to the plate-based method. Therefore, the FCM-based method might be a potential primary method for characterizing bacterial RMs. To our knowledge, this is the first description of FCM as a potential primary method for accurate and traceable quantification of viable bacterial cells with a comprehensive uncertainty statement in microbiological metrology.