خيارات البحث
النتائج 361 - 370 من 7,292
The behavior of organic sulfur species in fuel during chemical looping gasification النص الكامل
2022
Wang, Lulu | Shen, Laihong | Long, Yuyang | Shen, Dongsheng | Jiang, Shouxi
Uncoupling chemical looping gasification (CLG), the organic sulfur evolution was simulated and explored qualitatively and quantitatively using typical sulfur compounds on TG-MS and temperature-programmed fixed bed. The HS radical in the reductive atmosphere easier converted to H₂S and COS. H₂O activated the evolution of S which was stably bonded to carbon, and H₂ generated from gasification and oxidation of reductive Fe by H₂O contributed to the release of sulfur. The proportion of H₂S released from sulfur compounds was greater than 87% in steam gasification, and more than 60% during CLG. Oxygen carriers promoted the conversion of sulfur to SO₂ in the mid-temperature region (500 °C–700 °C), and H₂S in the high temperature region (700 °C–900 °C). Sulfur species played a pivotal role in sulfur evolution at low temperature of CLG. The organic sulfur in mercaptan and benzyl were more easily converted and escaped than in thiophene and phenyl. The thermal stability of sulfur species, the presence of steam and OC affected the initial temperature and peak concentration of gas sulfur release as well as sulfur distribution. Consequently, CLG strengthened the sulfur evolution, and made it possible to targeted restructure the distribution of sulfur by regulating process parameters, or blending fuel with different sulfur species for emission reduction, and selective conversion of sulfur.
اظهر المزيد [+] اقل [-]Toxicity assessment of historical aqueous film-forming foams (AFFFs) using cell-based assays النص الكامل
2022
Ojo, Atinuke F. | Peng, Cheng | Annamalai, Prasath | Megharaj, Mallavarapu | Ng, J. (Jack)
Aqueous film-forming foam (AFFF) has historically contained high concentrations of long-chain per-and polyfluoroalkyl substances (PFAS), which have been linked with adverse health outcomes. However, the toxicity of historical AFFFs remains largely unknown, presenting uncertainties in their risk assessment. This study assessed the toxicity of historical AFFFs by exposing human liver cells (HepG2) to various dilutions of 3M Light Water AFFF or Ansulite AFFF (0.001%, 0.002%, 0.005%, 0.009%, 0.019%, 0.038%, 0.075%, 0.15%, and 0.3%) for 24 h. The effects of the two AFFF formulations on the cell viability, intracellular reactive oxygen species (ROS) production, Nrf2-ARE activity, and DNA damage were assessed by CellTiter 96® Aqᵤₑₒᵤₛ One Solution Cell Proliferation Assay (MTS kit), dichlorofluorescein diacetate assay, luciferase assay, and alkaline Comet assay, respectively. The results revealed that the two brands of AFFFs tested were toxic to HepG2 cells at dilutions lower than the recommended 3% application formulation. Specifically, exposure to 3M Light Water AFFF or Ansulite AFFF induced a dilution-dependent decrease in cell viability, increased intracellular ROS production, and increased Nrf2-ARE activity. However, except for the highest concentration (lowest dilution) of 3M Light Water AFFF tested (0.038%.), both 3M Light Water AFFF and Ansulite AFFF did not significantly induce cellular DNA damage. Overall, 3M Light Water AFFF was more toxic than Ansulite AFFF. The findings from this study provided valuable in vitro toxicity data that may better inform the health risk assessment of these historical AFFFs.
اظهر المزيد [+] اقل [-]Unraveling the dynamics of organic micropollutants in wastewater: Online LC-MS/MS analysis at high temporal resolution النص الكامل
2022
Köke, Niklas | Solano, Fernando | Knepper, T. P. (Thomas P.) | Frömel, Tobias
Online monitoring of organic micropollutants (OMPs) in the aquatic environment at high temporal resolution is an upcoming technique that provides insights into their dynamics and has the potential to bring water research and management to a new level. An online monitoring setup was developed to quantify OMPs in wastewater treatment plant (WWTP) influent and effluent using automated and continuous sampling, sample preparation, online solid-phase extraction-liquid chromatography-tandem mass spectrometry analysis and data evaluation. This online monitoring setup provided high selectivity and sensitivity (limit of quantification down to 1 ng/L) as well as a stable performance during one week of constant operation whilst using a high sampling frequency of 10 min (>1000 samples). Custom automated data evaluation enabled quantification within seconds after each measurement and results were comparable to those from a commercial software. Additionally, an alarm tool was included in the evaluation application, which automatically notified the user in case a substance exceeded a predefined threshold. The online monitoring setup was applied to WWTP influent and effluent, where 57 substances were monitored over a period of one week and two days, respectively. High temporal resolution enabled the observation of periodic patterns of pharmaceuticals as well as pollution by OMPs originating from point and diffuse sources, while dynamics of OMPs in WWTP effluent were less pronounced. These new insights into the dynamics of OMPs in WWTP influent, which would not be observable using 24 h composite samples, will be a starting point for new stormwater and wastewater research and management strategies.
اظهر المزيد [+] اقل [-]Impacts of microplastics on scleractinian corals nearshore Liuqiu Island southwestern Taiwan النص الكامل
2022
Lim, Yee Cheng | Chen, Chiu-Wen | Cheng, Yu-Rong | Chen, Chih-Feng | Dong, Cheng-Di
Seawater, sediments, and three genera of wild scleractinian corals were collected from four coral reef areas nearshore Liuqiu Island, southwestern Taiwan. Abundance, characteristics (sizes, colors, shapes, and polymer types), and enrichment of microplastics (MPs) in the corals, and their impacts on coral cover were determined. The average MPs abundances were 0.95, 0.77, and 0.36 item/g for Galaxea sp, Acropora spp, and Pocillopora sp, respectively. The MPs abundance was relatively higher on the coral surfaces than inside the skeletons, dominated by blue rayon-fibers, correspondingly observed in seawater and sediments. Large-size colorless MPs tended to be mis-ingested by Galaxea sp. (71%) compared with Pocillopora sp. (43%) and Acropora spp. (31%). The low hard coral cover (12.5%) observed at Yufu (L1) on the northeastern coastal zone nearby tourism center of Liuqiu Island where correspondingly associated with high MPs abundance in seawater (10 item/L), sediments (260 item/kg), and corals (0.60 item/g). Tourism induced sewage discharges and sailing activities significantly contributed to the MPs pollution, probably contributing to the loss of coral cover. High MPs enrichment in corals (EFMP = 25–283) shows that the marine MPs pollution can critically threaten coral reef ecosystems. Fibrous MPs present inside the coral skeleton serve as potential indicator of MPs’ impact on corals—with the dominance of textile-related rayon and polyester/PET microfibers in the coral reef zones. This study provided valuable information for coral conservation and coastal management.
اظهر المزيد [+] اقل [-]Impact of biosurfactant and iron nanoparticles on biodegradation of polyaromatic hydrocarbons (PAHs) النص الكامل
2022
Parthipan, Punniyakotti | Cheng, Liang | Dhandapani, Perumal | Elumalai, Punniyakotti | Huang, Mingzhi | Rajasekar, Aruliah
Polycyclic aromatic hydrocarbons (PAHs) are hazardous toxic contaminants and considered as primary pollutants due to their persistent nature and most of them are carcinogenic and mutagenic. The key challenge in PAHs degradation is their hydrophobic nature, which makes them one of the most complex materials and inaccessible by a broad range of microorganisms. This bioavailability can be increased by using a biosurfactant. In the present study mixed PAHs were degraded using the biosurfactant producing bacterial strains. In addition, iron nanoparticles were synthesized and the impact of iron nanoparticles on the growth of the mixed bacterial strains (Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3) was optimized. The mixed PAHs (anthracene, pyrene, and benzo(a)pyrene) degradation was enhanced by addition of biosurfactant (produced by Bacillus subtilis A1) and iron nanoparticles, resulting in 85% of degradation efficiency. The addition of the biosurfactant increased the bioavailability of the PAHs in the aqueous environment, which might help bacterial cells for the initial settlement and development. The addition of iron nanoparticles increased both bacterial biomass and PAHs adsorption over their surface. These overall interactions assisted in the utilization of PAHs by the mixed bacterial consortia. This study illustrates that this integrated approach can be elaborated for the removal of the complex PAHs pollutants from soil and aqueous environments.
اظهر المزيد [+] اقل [-]New insights into cyanobacterial blooms and the response of associated microbial communities in freshwater ecosystems النص الكامل
2022
Du, Caili | Li, Guowen | Xia, Rui | Li, Caole | Zhu, Qiuheng | Li, Xiaoguang | Li, Jiaxi | Zhao, Chen | Tian, Zhenjun | Zhang, Lieyu
Cyanobacterial blooms are important environmental problems in aquatic ecosystems. Researchers have found that cyanobacterial blooms cannot be completely prevented by controlling and/or eliminating pollutants (nutrients). Thus, more in-depth basic research on the mechanism of cyanobacterial blooms is urgently needed. Cyanobacteria, being primordial microorganisms, provide habitats and have various forms of interactions (reciprocity and competition) with microorganisms, thus having a significant impact on themselves. However, little is known about how environmental conditions and microbial communities in both water and sediment jointly affect cyanobacterial blooms or about the co-occurrence patterns and interactions of microbial communities. We investigated changes in environmental factors and microbial communities in water and sediment during different cyanobacterial blooms and revealed their interacting effects on cyanobacteria. Cyanobacteria had greater competitive and growth advantages than other microorganisms and had antagonistic and aggressive effects on them when resources (such as nutrients) were abundant. Furthermore, microbial networks from cyanobacterial degradation periods may be more complex and stable than those from bloom periods, with more positive links among the microbial networks, suggesting that microbial community structures strengthen interconnections with each other to degrade cyanobacteria. In addition, we found that sediment-enriched cyanobacteria play a key role in cyanobacterial blooms, and sediment microorganisms promote the nutrient release, further promoting cyanobacterial blooms in the water bodies. The study contributes to further our understanding of the mechanisms for cyanobacterial blooms and microbial community structural composition, co-occurrence patterns, and responses to cyanobacteria. These results can contribute to future management strategies for controlling cyanobacterial blooms in freshwater ecosystems.
اظهر المزيد [+] اقل [-]Effects of long-term exposure to the herbicide nicosulfuron on the bacterial community structure in a factory field النص الكامل
2022
Ma, Qingyun | Tan, Hao | Song, Jinlong | Li, Miaomiao | Wang, Zhiye | Parales, Rebecca E. | Li, Lin | Ruan, Zhiyong
This study aims to investigate the effects of long-term nicosulfuron residue on an herbicide factory ecosystem. High-throughput sequencing was used to investigate the environmental microbial community structure and interactions. The results showed that the main contributor to the differences in the microbial community structure was the sample type, followed by oxygen content, pH and nicosulfuron residue concentration. Regardless of the presence or absence of nicosulfuron, soil, sludge, and sewage were dominated by groups of Bacteroidetes, Actinobacteria, and Proteobacteria. Long-term exposure to nicosulfuron increased alpha diversity of bacteria and archaea but significantly decreased the abundance of Bacteroidetes and Acidobateria compared to soils without nicosulfuron residue. A total of 81 possible nicosulfuron-degrading bacterial genera, e.g., Rhodococcus, Chryseobacterium, Thermomonas, Stenotrophomonas, and Bacillus, were isolated from the nicosulfuron factory environmental samples through culturomics. The co-occurrence network analysis indicated that the keystone taxa were Rhodococcus, Stenotrophomonas, Nitrospira, Terrimonas, and Nitrosomonadaceae_MND1. The strong ecological relationship between microorganisms with the same network module was related to anaerobic respiration, the carbon and nitrogen cycle, and the degradation of environmental contaminants. Synthetic community (SynCom), which provides an effective top-down approach for the critical degradation strains obtained, enhanced the degradation efficiency of nicosulfuron. The results indicated that Rhodococcus sp. was the key genus in the environment of long-term nicosulfuron exposure.
اظهر المزيد [+] اقل [-]Roles of H19/miR-29a-3p/COL1A1 axis in COE-induced lung cancer النص الكامل
2022
Zhang, Heng | Li, Xinmei | Jia, Mengmeng | Ji, Jing | Wu, Zhaoxu | Chen, Xian | Yu, Dianke | Zheng, Yuxin | Zhao, Yanjie
Occupational lung cancer caused by coke oven emissions (COE) has attracted increasing attention, but the mechanism is not clear. Many evidences show ceRNA (competing endogenous RNA) networks play important regulatory roles in cancers. In this study, we aimed to construct and verify the ceRNA regulatory network in the occurrence of COE-induced lung squamous cell carcinoma (LUSC). We performed RNA sequencing with lung bronchial epithelial cell (16HBE) and COE induced malignant transformed cell (Rf). Furthermore, we analyzed RNA sequencing data of LUSC and adjacent tissues in the cancer genome atlas (TCGA) database. Combined our data and TCGA data to determine the differentially expressed lncRNAs, miRNAs, mRNAs. lncBASE, miRDB and miRTarBase were used to predict the binding relationship between lncRNA and miRNA, miRNA and mRNA. Based on these, we construct the ceRNA network. FREMSA, dual-luciferase reporter assay, quantitative real-time PCR (qRT-PCR), western-blot were used to verify the regulatory axis. CCK8 assay, phalloidin staining, p53 detection were used to explore the roles of this axis in the COE induced malignant transformation. Results showed 7 lncRNAs, 7 miRNAs and 146 mRNAs were identified. Among these, we constructed a ceRNA network including 1 lncRNA, 2 miRNAs and 9 mRNAs. Further verification confirmed the trend of lncRNA H19, miR-29a-3p and COL1A1 were consistent with sequencing results. H19 and COL1A1 were significantly higher in Rf than in 16HBE and miR-29a-3p was reverse. Regulatory investigation revealed H19 increased COL1A1 expression by sponging miR-29a-3p. Knockdown of H19, COL1A1 or overexpression of miR-29a-3p in Rf cells could inhibit cell proliferation, increased cell adhesion and p53 level. However, knockdown of H19 while suppressing the miR-29a-3p partially rescue the malignant phenotype of Rf caused by H19. In conclusion, all these indicated H19 functioned as a ceRNA to increase COL1A1 by sponging miR-29a-3p and promoted COE-induced cell malignant transformation.
اظهر المزيد [+] اقل [-]Legacy metal contamination is reflected in the fish gut microbiome in an urbanised estuary النص الكامل
2022
Suzzi, Alessandra L. | Stat, Michael | MacFarlane, Geoff R. | Seymour, Justin R. | Williams, Nathan LR. | Gaston, Troy F. | Alam, Md Rushna | Huggett, Megan J.
Estuaries are critical habitats subject to a range of stressors requiring effective management. Microbes are gaining recognition as effective environmental indicators, however, the response of host associated communities to stressors remains poorly understood. We examined microbial communities from seawater, sediments and the estuarine fish Pelates sexlineatus, in Australia's largest urbanised estuary, and hypothesised that anthropogenic contamination would be reflected in the microbiology of these sample types. The human faecal markers Lachno3 and HF183 were not detected, indicating negligible influence of sewage, but a gradient in copy numbers of the class 1 integron (intI-1), which is often used as a marker for anthropogenic contamination, was observed in sediments and positively correlated with metal concentrations. While seawater communities were not strongly driven by metal contamination, shifts in the diversity and composition of the fish gut microbiome were observed, with statistical links to levels of metal contamination (F₂, ₂₁ = 1.536, p < 0.01). Within the fish gut microbiome, we further report increased relative abundance of amplicon sequence variants (ASVs; single inferred DNA sequences obtained in sequencing) identified as metal resistant and potentially pathogenic genera, as well as those that may have roles in inflammation. These results demonstrate that microbial communities from distinct habitats within estuarine systems have unique response to stressors, and alterations of the fish gut microbiome may have implications for the adaptation of estuarine fish to legacy metal contamination.
اظهر المزيد [+] اقل [-]Enhanced Cd2+ adsorption and toxicity for microbial biofilms in the presence of TiO2 nanoparticles النص الكامل
2022
Wang, Wenwen | Zhu, Shijun | Li, Nihong | Xie, Shanshan | Wen, Chen | Luo, Xia
Titanium dioxide nanoparticles (TiO₂ NPs) easily combine with other pollutants such as heavy metals because of their excellent physiochemical properties. However, how such an interaction may affect the binding behavior of metals onto biofilms remains largely unclear. This study, examined the effects of TiO₂ NPs on Cd²⁺ accumulation and toxicity for natural periphytic biofilms were examined. The adsorption kinetics showed that adding 0.1 and 1 mg/L TiO₂–NPs increased the Cd²⁺ adsorption of biofilms at equilibrium by 23.5% and 35.8%, respectively. However, adding 10 mg/L TiO₂ NPs increased the Cd²⁺ adsorption of biofilms at equilibrium by only 1.9%. The adsorption isotherms indicate that the presence of TiO₂ NPs considerably increased the Cd²⁺ adsorption capacity of the biofilms; however, this effect became less prominent at high TiO₂ NP concentrations. The optimum pH for Cd²⁺ adsorption increased with increasing Cd²⁺ and TiO₂ NP contents. At low concentrations, the coexistence of Cd²⁺ and TiO₂ NPs may facilitate their respective accumulation by stimulating the secretion of extracellular polymeric substances and enhancing the microbial activity of the biofilm. The presence of TiO₂ NPs increases the surface binding energy between Cd²⁺ and functional groups such as carboxyl groups, enhancing the Cd²⁺ accumulation on the biofilm.
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