SEEI: spherical evolution with feedback mechanism for identifying epistatic interactions.

BACKGROUND: Detecting epistatic interactions (EIs) involves the exploration of associations among single nucleotide polymorphisms (SNPs) and complex diseases, which is an important task in genome-wide association studies. The EI detection problem is dependent on epistasis models and corresponding optimization methods. Although various models and methods have been proposed to detect EIs, identifying EIs efficiently and accurately is still a challenge. RESULTS: Here, we propose a linear mixed statistical epistasis model (LMSE) and a spherical evolution approach with a feedback mechanism (named SEEI). The LMSE model expands the existing single epistasis models such as LR-Score, K2-Score, Mutual information, and Gini index. The SEEI includes an adaptive spherical search strategy and population updating strategy, which ensures that the algorithm is not easily trapped in local optima. We analyzed the performances of 8 random disease models, 12 disease models with marginal effects, 30 disease models without marginal effects, and 10 high-order disease models. The 60 simulated disease models and a real breast cancer dataset were used to evaluate eight algorithms (SEEI, EACO, EpiACO, FDHEIW, MP-HS-DHSI, NHSA-DHSC, SNPHarvester, CSE). Three evaluation criteria (pow1, pow2, pow3), a T-test, and a Friedman test were used to compare the performances of these algorithms. The results show that the SEEI algorithm (order 1, averages ranks = 13.125) outperformed the other algorithms in detecting EIs. CONCLUSIONS: Here, we propose an LMSE model and an evolutionary computing method (SEEI) to solve the optimization problem of the LMSE model. The proposed method performed better than the other seven algorithms tested in its ability to identify EIs in genome-wide association datasets. We identified new SNP-SNP combinations in the real breast cancer dataset and verified the results. Our findings provide new insights for the diagnosis and treatment of breast cancer. AVAILABILITY AND IMPLEMENTATION: https://github.com/scutdy/SSO/blob/master/SEEI.zip .

Therapeutic Plasma Exchange in AChR-Ab Positive Generalized Myasthenia Gravis: A Real World Study About Its Early Response.

Background: Since there is no clear priority or selection principle in the guidelines for myasthenia crisis, therapeutic plasma exchange (TPE) and intravenous immunoglobulin are often administered randomly. However, it should be more prudent in taking TPE due to its higher cost and risk. Studying its early response factors is crucial for managing myasthenia crisis and can improve medical and economic benefits. Methods: A prospective observational study was conducted, and patients classified as having "impending myasthenia crisis" or experiencing a myasthenia crisis and treated by TPE were included. The primary endpoint was the response after TPE. Univariate logistic regression analysis and repeated measurement were performed to analyze factors related to TPE efficacy. Results: A total of 30 patients who treated with TPE as their fast-acting treatments were enrolled. After TPE, those whose QMGs and/or MGCs decreased by ≥5 points or ≥30% of the baseline were judged as "response group", accounting for 66.67% (20/30). Respiratory symptoms had a response rate of 72.00% (18/25), showing the most remarkable improvement. Meanwhile, extraocular symptoms were the least sensitive, with only 8.00% (2/25) showing efficacy. Thymoma (100.00% vs 50.00%, P=0.002) and a high concentration of AChR-Ab (37.37 nmol/L vs 25.4 nmol/L, P=0.039) were common in the early response group. Repeated measures showed significant changes in AChR-Ab and CD19+ B cells before and after TPE (all with P < 0.05). After treatment, the CD19+ B cells tended to decrease in the response group. Discussion: These results indicated that, for AChR-Ab positive generalized MG, TPE can quickly improve respiratory symptoms. Thymoma and a high concentration of AChR-Ab before TPE predict an early better response. Additionally, TPE may work by decreasing AChR-Ab levels and inducing immune regulation. Future prospective and randomized controlled studies are needed.

Iron 3D-Orbital Configuration Dependent Electron Transfer for Efficient Fenton-Like Catalysis.

Transition metals are excellent active sites to activate peroxymonosulfate (PMS) for water treatment, but the favorable electronic structures governing  reaction mechanism still remain elusive. Herein, the authors construct typical d-orbital configurations on iron octahedral (FeOh ) and tetrahedral (FeTd ) sites in spinel ZnFe2 O4 and FeAl2 O4 , respectively. ZnFe2 O4 (136.58 min-1 F-1 cm2 ) presented higher specific activity than FeAl2 O4 (97.47 min-1 F-1 cm2 ) for tetracycline removal by PMS activation. Considering orbital features of charge amount, spin state, and orbital arrangement by magnetic spectroscopic analysis, ZnFe2 O4 has a larger bond order to decompose PMS. Using this descriptor, high-spin FeOh is assumed to activate PMS mainly to produce nonradical reactive oxygen species (ROS) while high-spin FeTd prefers to induce radical species. This hypothesis is confirmed by the selective predominant ROS of 1 O2 on ZnFe2 O4 and O2 •- on FeAl2 O4 via quenching experiments. Electrochemical determinations reveal that FeOh has superior capability than FeTd for feasible valence transformation of iron cations and fast interfacial electron transfer. DFT calculations further suggest octahedral d-orbital configuration of ZnFe2 O4 is beneficial to enhancing Fe-O covalence for electron exchange. This work attempts to understand the d-orbital configuration-dependent PMS activation to design efficient catalysts.

Study of serum exosome miRNA as a biomarker for early onset adult ouclar myastthenia gravis.

BACKGROUND: By extracting and sequencing miRNAs from serum exosomes of patients with early-onset ocular myasthenia gravis (OMG), generalized myasthenia gravis (GMG) and healthy controls, we screened differentially expressed miRNAs and explored the possibility as potential biomarkers for early-onset OMG. METHODS: Peripheral blood samples were collected from patients with early-onset OMG, early-onset GMG, and age-matched healthy subjects, with 6 samples in each group. All these patients were diagnosed as MG for the first time and did not undergo any treatment. Exosomes miRNAs were extracted from the serum and performed deep sequencing; the differentially expressed miRNAs were compared and analyzed between OMG, GMG, and healthy control groups using edgeR. The differential expression standard was set to | log2FC |>1, p < 0.05. Target prediction of mRNAs were performed using miRTarBase, TargetScan, and miRDB databases, and a protein-protein interaction (PPI) network was constructed subsequently. The miRNAs with a significant difference were validated using RT-qPCR (10 early-onset OMG patients, 10 early-onset GMG patients and 10 age-sex-matched healthy subjects), and the value of the area under the ROC curve (AUC) was used to assess the diagnostic accuracy and evaluate clinical prognostic value. RESULTS: In total, one upregulated (miR-130a-3p) miRNA was obtained through the upregulated intersection between control vs OMG and OMG vs GMG; four downregulated (miR-4712-3p; miR-6752-5p; miR-320d; miR-3614-3p) miRNAs were obtained through the downregulated intersection between control vs OMG and OMG vs GMG. A total of 408 target genes were predicted for the five differentially expressed miRNAs. The mTOR signaling pathway and Rap1 signaling pathway were significantly enriched based on the enrichment results. RT-qPCR findings revealed that for the OMG, the expression of miR-320d, miR-4712-3p and miR-3614-3p was markedly up-/down-regulated as compared to GMG and healthy control group. The AUC for the three miRNAs between OMG and healthy control groups were 0.78, 0.79 and 0.79 respectively; the AUC between OMG and GMG was 0.84. CONCLUSIONS: The present study identified three novel miRNAs as candidate biomarkers for early-onset OMG patients and it was expected to provide a possibility and a new orientation for serum exosomal miRNAs as OMG diagnostic biomarkers.

Identification and functional prediction of long non-coding RNAs related to oxidative stress in the jejunum of piglets.

OBJECTIVE: Oxidative stress (OS) is a pathological process arising from the excessive production of free radicals in the body. It has the potential to alter animal gene expression and cause damage to the jejunum. However, there have been few reports of changes in the expression of long noncoding RNAs (lncRNAs) in the jejunum in piglets under OS. The purpose of this research was to examine how lncRNAs in piglet jejunum change under OS. METHODS: The abdominal cavities of piglets were injected with diquat (DQ) to produce OS. Raw reads were downloaded from the SRA database. RNA-seq was utilized to study the expression of lncRNAs in piglets under OS. Additionally, six randomly selected lncRNAs were verified using quantitative real-time polymerase chain reaction (qRT‒PCR) to examine the mechanism of oxidative damage. RESULTS: A total of 79 lncRNAs were differentially expressed (DE) in the treatment group compared to the negative control group. The target genes of DE lncRNAs were enriched in gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes (KEGG) signaling pathways. Chemical carcinogenesis-reactive oxygen species, the Foxo signaling pathway, colorectal cancer, and the AMPK signaling pathway were all linked to OS. CONCLUSION: Our results demonstrated that DQ-induced OS causes differential expression of lncRNAs, laying the groundwork for future research into the processes involved in the jejunum's response to OS.

Gas-particle partitioning of organophosphate esters in indoor and outdoor air and its implications for individual exposure.

The extensive utilization of organophosphate esters (OPEs) has resulted in their widespread presence in the environment, raising concerns about potential human health risks. In this study, 13 OPEs were analyzed in both gas and particle phases as well as in indoor and outdoor atmospheric environments. Moreover, human exposure to OPEs were investigated within a university environment, focusing on forehead contact and individual PM2.5 inhalation. The results showed similar distribution patterns of OPEs indoors and outdoors, although higher concentrations were found indoors. The average atmospheric concentration of ∑OPEs (combining particle and gaseous OPEs) was 1575 pg/m3 in the outdoor environment and 6574 pg/m3 ∑OPEs in the indoor microenvironments. The overwhelming majority of OPEs exhibit a pronounced propensity to adsorb onto PM2.5 particles. Notably, the concentration of OPEs on the forehead differed significantly from that in the atmospheric environment, whereas individual PM2.5 exposure was consistent with the concentration of indoor PM2.5. Intriguingly, some OPEs with high octanol-water partition coefficient (log Kow) were not detected in the environment but found on human foreheads. Gas-particle partitioning was predicted using the Harner-Bidleman and Li-Ma-Yang models and the results were in agreement with the monitoring data for approximately half of the OPE monomers. Correlations between OPEs exposure and gas-particle partitioning were found to be more significant for novel OPEs. No non-cancer risk to humans through individual exposure to OPEs was identified via forehead exposure or inhalation. The previously unreported relationship between individual exposure and the environmental occurrence of traditional and novel OPEs demonstrated in this study highlights the importance of evaluating the potential health risks associated with actual OPE exposure.

Indoor exposure to polycyclic aromatic hydrocarbons associated with solid fuel use in rural China.

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants associated with various health risks including lung cancer. Indoor exposure to PAHs, particularly from the indoor burning of fuels, is significant; however, long-term large-scale assessments of indoor PAHs are hampered by high costs and time-consuming in field sampling and laboratory experiments. A simple fuel-based approach and statistical regression models were developed as a trial to predict indoor BaP, as a typical PAH, in China, and consequently spatiotemporal variations in indoor BaP and indoor exposure contributions were discussed. The results show that the national population-weighted indoor BaP concentration has decreased substantially from 46.1 ng/m3 in 1992 to 6.60 ng/m3 in 2017, primarily due to the increased use of clean energies for cooking and heating. Indoor BaP exposure contributed to > 70% of the total inhalation exposure in most cities, particularly in regions where solid fuels are widely utilized. With limited experimental observation data in building statistical models, quantitative results of the study are associated with high uncertainties; however, the study undoubtedly supports effective countermeasures on indoor PAHs from solid fuel use and the importance of promoting clean household energy usage to improve household air quality.

Sublobar resection reduces the risk of postoperative cognitive dysfunction compared with lobectomy.

OBJECTIVES: Sublobar resection, including wedge resection and segmentectomy, is non-inferior to lobectomy in early-stage non-small cell lung cancer treatment. We aimed to compare the risk of postoperative cognitive dysfunction (POCD) between sublobar resection and lobectomy. METHODS: We conducted a prospective cohort study. Patients with sublobar resection or lobectomy were divided into the sublobar group or the lobar group, respectively. Cognition was assessed before and after surgery with Montreal Cognitive Assessment and Minimum Mental State Examination tests. POCD is defined as Z score of Montreal Cognitive Assessment change ≤-1.96. Propensity score matching (PSM) was performed to make demographics well-balanced between the 2 groups. RESULTS: A total of 335 patients were enrolled. Both the postoperative 1-day POCD rate (sublobar 5.5% vs lobar 18.2%, P < 0.001) and the postoperative 1-month POCD rate (sublobar 7.9% vs lobar 21.8%, P < 0.001) were significantly lower in the sublobar group compared with lobar group, with demographics unbalanced between the 2 groups. In the 133 demographics-matched pairs obtained by PSM, both the postoperative 1-day POCD rate (sublobar 5.3% vs lobar 17.3%, P = 0.005) and the postoperative 1-month POCD rate (sublobar 8.3% vs lobar 18.8%, P = 0.018) remained significantly lower in the sublobar group than in the lobar group. The incidences of postoperative 1-day (P = 0.109) and postoperative 1-month (P = 0.026) Minimum Mental State Examination abnormity were also lower in the sublobar group than in the lobar group but only the latter was with statistical significance after PSM. CONCLUSIONS: Sublobar resection has an advantage over lobectomy in preventing POCD. Our findings might be a reference for selecting the most suitable type of resection for non-small-cell lung cancer patients.

Prevalence, risk factors, and mortality of COPD in young people in the USA: results from a population-based retrospective cohort.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) has been considered a disease of the elderly, but it could also occur in young people aged 20-50 years. However, the characteristics and prognosis of COPD in such young people remain unclear. METHODS: Our retrospective cohort study was based on the National Health and Nutrition Examination Survey (NHANES). Participants who 20-50 years old at baseline and completed the pulmonary function test were enrolled in our study cohort. These participants were followed up to 31 December 2019. The sample weight and Taylor Linearization Procedures were adapted to make representative estimations of prevalence and baseline characteristics. The weighted logistic regression model was used to assess the risk factors. The propensity score method and Cox proportional hazard models were applied to calculate the risk of mortality. RESULTS: The weighted prevalence of COPD in young people in the USA was 1.64% and it increased with age, with a higher prevalence in males than females (2.59% vs 0.72%, p<0.001). The proportion of Global Initiative for COPD 1-2 was 96.7%. Males (OR=4.56, 95% CI: 2.74 to 7.61), non-Hispanic black (OR=2.77; 95% CI: 1.14 to 6.75), non-Hispanic white (OR=4.93; 95% CI: 2.16 to 11.28) and smoking (current smoking, OR=2.36; 95% CI: 1.40 to 3.98; ever smoking, OR=1.92; 95% CI: 1.05 to 3.51; passive smoking, OR=2.12; 95% CI: 1.41 to 3.20) were shown to be independent risk factors for COPD in young people. Compared with those matched by sex, age and race, the young people with COPD had a higher risk of all-cause death (HR=3.314, p<0.001). CONCLUSION: COPD in young people has a low prevalence in the USA and its independent risk factors included male, race (non-Hispanic black and non-Hispanic white) and smoking. Young COPD has a higher risk of all-cause mortality than the matched non-COPD.

Inventory, source and health risk assessment of nitrated and parent PAHs in agricultural soils over a rural river in Southeast China.

Nitrated polycyclic aromatic hydrocarbons (NPAHs) have become a concerning topic because of their widespread occurrence and carcinogenicity. However, studies on NPAHs in soils, especially in agricultural soils, are still limited. In this study, a systematic monitoring campaign of 15 NPAHs and 16 polycyclic aromatic hydrocarbons (PAHs) was performed in agricultural soils from the Taige Canal basin in 2018, which is a typical agricultural activity area of the Yangtze River Delta. The total concentration of NPAHs and PAHs ranged from 14.4 to 85.5 ng g-1 and 118-1108 ng g-1, respectively. Among the target analytes, 1,8-dinitropyrene and fluoranthene were the most predominant congeners accounting for 35.0% of ∑15NPAHs and 17.2% of ∑16PAHs, respectively. Four-ring NPAHs and PAHs were predominant, followed by three-ring NPAHs and PAHs. NPAHs and PAHs had a similar spatial distribution pattern with high concentrations in the northeastern Taige Canal basin. The soil mass inventory of ∑16PAHs and ∑15NPAHs was evaluated to be 31.7 and 2.55 metric tons, respectively. Total organic carbon had a significant impact on the distribution of PAHs in soils. The correlation between PAH congeners in agricultural soils was higher than that between NPAH congeners. Based on diagnostic ratios and principal component analysis-multiple linear regression model, vehicle exhaust emission, coal combustion, and biomass combustion were the predominant sources of these NPAHs and PAHs. According to the lifetime incremental carcinogenic risk model, the health risk posed by NPAHs and PAHs in agricultural soils of the Taige Canal basin was virtually negligible. The total health risk in soils of the Taige Canal basin to adults was slightly higher than that to children.

An innovative strategy to control Microcystis growth using tea polyphenols sustained-release particles: preparation, characterization, and inhibition mechanism.

Allelochemicals have been shown to inhibit cyanobacterial blooms for several years. In view of the disadvantages of "direct-added" mode, natural and pollution-free tea polyphenolic allelochemicals with good inhibitory effect on cyanobacteria were selected to prepare sustained-release particles by microcapsule technology. Results showed that the encapsulation efficiency of tea polyphenols sustained-release particles (TPSPs) was 50.6% and the particle size ranged from 700 to 970 nm, which reached the nanoscale under optimum preparation condition. Physical and chemical properties of TPSPs were characterized to prove that tea polyphenols were well encapsulated and the particles had good thermal stability. The optimal dosage of TPSPs was determined to be 0.3 g/L, at which the inhibition rate on Microcystis aeruginosa in logarithmic growth period could be maintained above 95%. Simultaneous decrease in algal density and chlorophyll-a content indicated that the photosynthesis of algal cells was affected leading to cell death. Significant changes of antioxidant enzyme activities suggested that Microcystis aeruginosa's antioxidant systems had been disrupted. Furthermore, TPSPs increased the concentration of O2- which led to lipid peroxidation of cell membrane and a subsequent increase in malondialdehyde (MDA) content. Meanwhile, the protein content, nucleic acid content, and electrical conductivity in culture medium rose significantly indicating the cell membrane was irreversibly damaged. This work can provide a basis for the utilization of environmentally friendly algal suppressants.

Integrated transcriptomic and metabolomic analysis of Microcystis aeruginosa exposed to artemisinin sustained-release microspheres.

Artemisinin sustained-release microspheres (ASMs) have been shown to inhibit Microcystis aeruginosa (M. aeruginosa) blooms. Previous studies have focused on inhibitory mechanism of ASMs on the physiological level of M. aeruginosa, but the algal inhibitory mechanism of ASMs has not been comprehensively and profoundly revealed. The study proposed to reveal the toxicity mechanism of ASMs on M. aeruginosa based on transcriptomics and metabolomics. After exposure to 0.2 g·L-1 ASMs for 7 days, M. aeruginosa biomass was significantly inhibited, with an inhibition rate (IR) of 47 % on day 7. Transcriptomic and metabolomic results showed that: (1) 478 differentially expressed genes (DEGs) and 251 differential metabolites (DMs) were obtained; (2) ASMs inhibited photosynthesis by blocking photosynthetic pigment synthesis, destroying photoreaction centers and photosynthetic carbon reactions; (3) ASMs reduced L-glutamic acid content and blocked glutathione (GSH) synthesis, leading to an imbalance in the antioxidant system; (4) ASM disrupted nitrogen metabolism and the hindered synthesis of various amino acids; (5) ASMs inhibited glyoxylate cycle and TCA cycle. This study provides an important prerequisite for the practical application of ASMs and a new perspective for the management of harmful algal blooms (HABs).

Nomogram for the acute exacerbation of acetylcholine receptor antibody-positive generalized myasthenia gravis.

BACKGROUND AND OBJECTIVE: An acute exacerbation of myasthenia gravis (MG) can lead to the life-threatening myasthenia crisis which can increase the in-hospital mortality. This study aimed to clarify the correlative factor of the severity and activity of MG and the predictors of its exacerbation. METHODS: A prospective study was conducted to compare the clinical characteristics of acetylcholine receptor antibody (AChR-Ab)-positive generalized MG during acute exacerbation (AE) and in a stable state (SS). Logistic regression was used to determine risk factors, and a nomogram was developed. RESULTS: A total of 97 AChR-Ab MG patients were enrolled, of whom 44 had AE and 53 were in SS. The concentrations of AChR-Ab were 35.24 (23.26, 42.52) nmol/L and 19.51 (8.30, 36.93) nmol/L in the AE and SS groups (P = 0.005), respectively. The receiver operating characteristic curve showed that a single AChR-Ab predicted severity and acute exacerbation, with an area under the curve (AUC) of 0.679. Logistic regression analysis showed that, in addition to AChR-Ab (P = 0.018), bulbar symptoms (P = 0.001), interleukin (IL)-6 (P = 0.025), CD4+/CD8+ T cell ratio (P = 0.031), and CD19+ B cell proportion (P = 0.019) were independent risk factors for acute exacerbation of MG. The developed nomogram had an AUC of 0.878. The Hosmer and Lemeshow chi-square test was 4.37 (P = 0.929). CONCLUSION: AChR-Ab concentration was positively correlated with the severity and activity of MG. AChR-Ab concentration, alongside bulbar symptoms, IL-6 concentration, CD4+/CD8+ T cell ratio, and CD19+ B cell proportion can predict the acute exacerbation of MG.

Occurrence, partition behavior, source and ecological risk assessment of nitro-PAHs in the sediment and water of Taige Canal, China.

Nitrated polycyclic aromatic hydrocarbons (NPAHs) are widespread organic pollutants that possess carcinogenic and mutagenic properties, so they may pose a risk to the environment and human health. In this study, the concentrations of 15 NPAHs and 16 polycyclic aromatic hydrocarbons (PAHs) in 30 surface water samples and 26 sediment samples were measured in 2018 from the Taige Canal, one of the main rivers flowing into Taihu Lake, China. The total NPAH concentrations in water and sediment ranged from 14.7 to 235 ng/L and 22.9 to 96.5 ng/g dw, respectively. 9-nitrophenanthrene (nd-76.3 ng/L) was the dominant compound in surface water, while 2+3-nitrofluoranthene (1.73-18.1 ng/g dw) dominated in sediment. Among PAHs, concentration ranging from 1,097 to 2,981 ng/L and 1,089 to 4,489 ng/g dw in surface water and sediment, respectively. There was a strong positive correlation between the log octanol-water partition coefficient (Kow) and log sediment-water partition coefficient due to hydrophobic interaction. The fugacity fraction value increased with the decrease of log Kow, and chrysene was transferred from water into sediment. The residual NPAHs in surface water and sediment of the Taige Canal have partial correlation. Diesel engine and coal combustion emissions were probably the principal sources of NPAHs in surface water and sediment. The results of ecological risk assessment showed that some NPAHs in water (e.g, 1-nitropyrene and 6-nitrochrysene) and sediment (e.g., 2-nitrobiphenyl, 5-nitroacenaphthene, 9-nitrophenanthrene and 2+3-nitrofluoranthene) had moderate ecological risks, which should be of concern.

The Spherical Evolutionary Multi-Objective (SEMO) Algorithm for Identifying Disease Multi-Locus SNP Interactions.

Single-nucleotide polymorphisms (SNPs), as disease-related biogenetic markers, are crucial in elucidating complex disease susceptibility and pathogenesis. Due to computational inefficiency, it is difficult to identify high-dimensional SNP interactions efficiently using combinatorial search methods, so the spherical evolutionary multi-objective (SEMO) algorithm for detecting multi-locus SNP interactions was proposed. The algorithm uses a spherical search factor and a feedback mechanism of excellent individual history memory to enhance the balance between search and acquisition. Moreover, a multi-objective fitness function based on the decomposition idea was used to evaluate the associations by combining two functions, K2-Score and LR-Score, as an objective function for the algorithm's evolutionary iterations. The performance evaluation of SEMO was compared with six state-of-the-art algorithms on a simulated dataset. The results showed that SEMO outperforms the comparative methods by detecting SNP interactions quickly and accurately with a shorter average run time. The SEMO algorithm was applied to the Wellcome Trust Case Control Consortium (WTCCC) breast cancer dataset and detected two- and three-point SNP interactions that were significantly associated with breast cancer, confirming the effectiveness of the algorithm. New combinations of SNPs associated with breast cancer were also identified, which will provide a new way to detect SNP interactions quickly and accurately.

Inactivation Mechanism of Algal Chlorophyll by Allelochemical Quercetin.

Cyanobacteria harmful algal blooms (CyanoHABs) are a global concern. Application of allelochemicals is a promising solution for cyanobacteria control, due to its high efficiency, low cost and ecological safety. Flavonoids (natural polyphenols produced by aquatic plants) are reported capable of effectively inhibiting the growth of algae; however, the molecular mechanism of algae chlorophyll inactivation is still unclear. In this study, quercetin was used as a typical flavonoid, to investigate the inactivation effect of allelochemical on Microcystis aeruginosa chlorophyll a. The absorption and fluorescence spectra showed that chlorophyll reacted with quercetin to form pheophytin, and the formation rate of pheophytin increased with increasing quercetin concentration (1 × 10-5-1 × 10-2 M). FTIR spectra and DFT calculation showed that Mg2+ complexed with the 3-OH and 4-C = O groups in the quercetin ring C so that chlorophyll was inactivated due to the loss of Mg2+ ions. Overall, this study revealed that quercetin inactivated chlorophyll a of cyanobacteria by capturing Mg2+ ions, providing insights into the molecular mechanisms of algal bloom control by allelochemicals.

Insights into the adsorption mechanism of tannic acid by a green synthesized nano-hydroxyapatite and its effect on aqueous Cu(II) removal.

The polyphenolic tannic acid (TA) has been widely used in the stabilization and surface modification of nanomaterials. The interaction mechanism of TA with the biogenic nano-hydroxyapatite (nHAP) and its environmental importance, however, are poorly understood. This study explored the adsorption of TA using the green synthesized, eggshell-derived nHAP and implications of this process for the removal of aqueous Cu(II) via batch adsorption experiments, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) investigations. TA adsorption by nHAP was a complex pH-dependent process and significantly correlated with TA molecule speciation and amphoteric properties of nHAP via multiple adsorption modes including surface complexation, electrostatic attraction, and hydrogen bond. The maximum TA adsorption amount was found to be 94.8 mg/g for less crystalline nHAP with lower calcination temperature. In the ternary Cu-TA-nHAP systems, TA promoted Cu(II) adsorption at pH < 5 and reduced Cu(II) uptake at pH > 5. Further studies of the effects of ionic strength and addition sequences, as well as Raman, FTIR, and XPS analyses revealed Cu(II) adsorption on nHAP was mainly dominated by inner-sphere surface complexation. These results can shed light on not only the utility of biogenic nHAP for TA and Cu(II) adsorption but also the evaluation of the effect of TA on the environmental behavior of heavy metals.

Adsorption behavior and mechanism of 9-Nitroanthracene on typical microplastics in aqueous solutions.

Microplastics and Nitropolycyclic aromatic hydrocarbons (NPAHs) are two types of emerging pollutants that are strong potential threats to aquatic ecosystems and organisms. The adsorption of NPAHs on microplastics may explain the fate and effects of NPAHs in natural environments. In this study, the adsorption behavior of 9-Nitroanthrene (9-NAnt) on polyethylene (PE), polypropylene (PP) and polystyrene (PS) was investigated. Kinetic experiments revealed that 9-NAnt was inclined to be adsorbed onto microplastics, especially PE, which had a large adsorption amount of 734 µg g-1. A linear isothermal model better described the isothermal adsorption process for 9-NAnt, which indicated that a hydrophobic distribution may be the main adsorption mechanism in an aqueous solution. Water environment factors, such as the pH and ionic strength, had negligible effects on the adsorption for PE. In contrast, alkaline and high ionic strength conditions resulted in the inhibition of adsorption of PP and PS. In addition, the particle size of microplastics was negatively correlated with the log Kd of 9-NAnt, and the performance of transient aging treatments on microplastics reduced their affinity for 9-NAnt, due to the addition of oxygen-containing functional groups. Above all, hydrophobic and electrostatic processes were the main adsorption mechanisms between microplastics and 9-NAnt.

Analysis of trace-level nitrated polycyclic aromatic hydrocarbons in water samples by solid-phase microextraction with gas chromatography and mass spectrometry.

A solid-phase microextraction coupled with gas chromatography and mass spectrometry method has been developed for the determination of ten nitrated polycyclic aromatic hydrocarbons in water samples. Five different kinds of commerical fibers were used to compare the extraction efficiency, including 65 µm polydimethylsiloxane/divinylbenzene, 100 µm polydimethylsiloxane, 30 µm polydimethylsiloxane, 7 µm polydimethylsiloxane, and 85 µm polyacrylate fibers. Five factors were also selected to optimize conditions, including extraction temperature, time, stirring speed, salt concentration, and headspace volume. Taguchi design was applied to design the experiments and obtain the best parameters. The results show that 65 µm polydimethylsiloxane/divinylbenzene fiber directly immersed into aqueous solution for 35 min at 55°C with a constant stirring rate of 1150 rpm were the optimal conditions. Under these conditions, the limits of quantification were 0.007-0.063 µg/L, and the relative standard deviation based on six replicates ranged from 2.8 to 9.5%. The spiked recoveries ranged from 69.1 to 110.1%. Intra- and inter day relative standard deviations at three concentration levels were less than 12%, and the recoveries were 66.4-111.5%. The proposed method is reliable for analyzing nitrated polycyclic aromatic hydrocarbons in different water samples.

The characterization of dissolved organic matter extracted from different sources and their influence on cadmium uptake by Microcystis aeruginosa.

The present study examines the uptake of the heavy metal cadmium (Cd) by Microcystis aeruginosa in the presence of dissolved organic matter (DOM) from different origins. The DOM used in the present study were extracted from soil, sediment taken from Meiliang Bay at Taihu Lake, and from M. aeruginosa cultured in the laboratory. The 3 different DOM samples were characterized using ultraviolet-visible absorption spectroscopy and Fourier transform infrared spectroscopy. The excitation-emission matrix (EEM) fluorescence spectroscopy was used to characterize the interactions of DOM with Cd2+ . The results showed that all types of DOM extracted from the 3 sources in the present study exhibited aliphatic and aromatic characteristics and contained hydroxyls, carbonyls, phenols, carboxyls, carbohydrates, amines, and ethers. Humic acids and fulvic acids proved to be the major components of DOM. The sediment DOM had the highest degrees of aromatization and humification among the samples. The results also showed that sediment and soil DOM samples had lower molecular weights than M. aeruginosa DOM. The DOM could react with Cd2+ by complexing to alter Cd speciation. When exposed to Cd, EEM fluorescence intensities of all 3 DOM types had a significant decrease, and the intracellular Cd content improved with increasing Cd concentrations. The addition of DOM greatly enhanced Cd uptake by M. aeruginosa compared with the control group. Environ Toxicol Chem 2017;36:1856-1863. © 2017 SETAC.