176 research outputs found

    The impact of external plant carbon sources on nitrogen removal and microbial community structure in vertical flow constructed wetlands

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    The present study was developed to explore nitrogen removal performance and associated microbial mechanisms of action in vertical flow constructed wetlands (VFCWs) when using external carbon sources. These analyses ultimately revealed that alkali-soaked Phragmites australis (P. australis) could serve as an effective plant carbon source, exhibiting the lower levels of total nitrogen (TN) release and the highest chemical oxygen demand (COD) of all tested carbon sources. Nitrogen removal efficiency improved following the addition of plant carbon sources, and under carbon/nitrogen (C/N) rations of 2, 4, 5, and 7, the VFCW system was able to remove 43.69%–75.76% TN, with the highest removal rate being observed at a C/N of 5. The abundance of denitrifying microorganisms such as Thiobaillus and Halomonas were also more enriched in VFCW1 than VFCW0, with stronger correlations in the microbial network community. A qPCR approach was used to analyze functional genes involved in denitrification, revealing that the addition of plant carbon sources was associated with increases in total gene abundance and the abundance of the denitrifying gene nirS, whereas no corresponding increase in amoA or nxrA abundance was observed. Higher total gene, amoA, and nxrA abundance were observed in the upper levels of these VFCW systems as compared to the lower layers, whereas nirS exhibited the opposite abundance pattern. Overall, these findings suggested that short-range denitrification is likely to be the primary denitrification process active in this VFCW system

    Is There a Pollution Haven Effect? Evidence from a Natural Experiment in China

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    In this paper, we investigate whether there is a pollution haven effect, specifically, the effect of environmental regulations on firm location. Our identification uses the Two Control Zones (TCZ) policy implemented by the Chinese government in 1998. The difference-in-differences (DID) estimation shows that cities with tougher environmental regulations attract less foreign direct investment (FDI). Specifically, being listed as a TCZ city causes the amount of FDI to drop by 41%. Our results are robust to various robustness checks on the validity of the DID estimation and other estimation concerns

    Is There a Pollution Haven Effect? Evidence from a Natural Experiment in China

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    In this paper, we investigate whether there is a pollution haven effect, specifically, the effect of environmental regulations on firm location. Our identification uses the Two Control Zones (TCZ) policy implemented by the Chinese government in 1998. The difference-in-differences (DID) estimation shows that cities with tougher environmental regulations attract less foreign direct investment (FDI). Specifically, being listed as a TCZ city causes the amount of FDI to drop by 41%. Our results are robust to various robustness checks on the validity of the DID estimation and other estimation concerns

    Evolution of magnetic field of the Quasar 1604+159 at pc scale

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    We have analyzed the total intensity, spectral index, linear polarization, and RM distributions at pc scale for the quasar 1604+159. The source was observed in 2002 and 2020 with the VLBA. Combining the MOJAVE results, we studied the evolution of the magnetic field. We detected a core-jet structure. The jet extends to a distance of ~25 mas. The jet shape varies slightly with time. We divided the source structure into the central region and the jet region. In the jet region, we find the polarized emission varies with time. The flatter spectral index values and EVPA direction indicate the possible existence of shocks, contributing to the variation. In the central region, the derived core shift index k_r values indicate that the core in 2002 is close to the equipartition case while deviating from it in 2020. The measured magnetic field strength in 2020 is two orders of magnitude lower than that in 2002. We detected transverse RM gradients, evidence of a helical magnetic field, in the core. At 15 GHz, in the place close to the jet base, the polarization direction changes significantly with time from perpendicular to parallel to the jet direction. The evolution of RM and magnetic field structure are potential reasons for the observed polarization change. The core |RM| in 2020 increases with frequency following a power law with index a = 2.7, suggesting a fast electron density fall-off in the medium with distance from the jet base.Comment: 24 pages, 14 figures, accepted for publication in Ap

    Integrative Analysis Reveals Key Circular RNA in Atrial Fibrillation

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    Circular RNAs (circRNAs) are an emerging class of RNA species that may play a critical regulatory role in gene expression control, which can serve as diagnostic biomarkers for many diseases due to their abundant, stable, and cell- or tissue-specific expression. However, the association between circRNAs and atrial fibrillation (AF) is still not clear. In this study, we used RNA sequencing data to identify and quantify the circRNAs. Differential expression analysis of the circRNAs identified 250 up- and 126 down-regulated circRNAs in AF subjects compared with healthy donors, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the parental genes of the dysregulated circRNAs indicated that the up-regulated parental genes may participate in the process of DNA damage under oxidative stress. Furthermore, to annotate the dysregulated circRNAs, we constructed and merged the competing endogenous RNA (ceRNA) network and protein-protein interaction (PPI) network, respectively. In the merged network, 130 of 246 dysregulated circRNAs were successfully characterized by more than one pathway. Notably, the five circRNAs, including chr9:15474007-15490122, chr16:75445723-75448593, hsa_circ_0007256, chr12:56563313-56563992, and hsa_circ_0003533, showed the highest significance by the enrichment analysis, and four of them were enriched in cytokine-cytokine receptor interaction. These dysregulated circRNAs may mainly participate in biological processes of inflammatory response. In conclusion, the present study identified a set of dysregulated circRNAs, and characterized their potential functions, which may be associated with inflammatory responses in AF. To our knowledge, this is the first study to uncover the association between circRNAs and AF, which not only improves our understanding of the roles of circRNAs in AF, but also provides candidates of potentially functional circRNAs for AF researchers

    Preventive Effect of Lactobacillus paracasei FZU103 on Alcoholic Liver Injury in Mice

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    Objective: To explore the preventive effect of Lactobacillus paracasei FZU103 (LP-FZU103) on alcoholic liver injury (ALI). Methods: Altogether 36 specific pathogen free- (SPF-) grade ICR mice were randomly divided into three groups: control, model and experimental (LP-FZU103 intervention). After the six-week experiment, body mass, organ coefficients, serum and liver biochemical indexes, liver histopathology and inflammatory cytokines, the transcription of liver function-related genes and intestinal flora composition were measured. Results: Compared with the model group, intervention of LP-FZU103 improved the organ coefficients and pathological liver damage in ALI mice, significantly reduced the levels of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) as well as the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum, increased the serum concentration of high-density lipoprotein cholesterol (HDL-C), significantly increased the activity of catalase (CAT) and superoxide dismutase (SOD) and the content of glutathione (GSH) in the liver, and decreased MDA content and interleukin-6 (IL-6), interferon-γ (IFN-γ) levels in the liver. Moreover, LP-FZU103 intervention significantly up-regulated the mRNA expression level of the lipid metabolism-related gene Ldlr and down-regulated the mRNA expression level of Acc1, Hmgcr and Cd36 as well as increased the relative abundance of beneficial bacteria such as Lactobacillus johnsonii, Lactobacillus reuteri and Lactobacillus paracasei in the gut of mice. Conclusion: LP-FZU103 intervention can prevent and control the occurrence of alcoholic liver injury in mice, which is closely related to the improved intestinal flora and liver metabolic function

    Tau-related white-matter alterations along spatially selective pathways

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    Progressive accumulation of tau neurofibrillary tangles in the brain is a defining pathologic feature of Alzheimer's disease (AD). Tau pathology exhibits a predictable spatiotemporal spreading pattern, but the underlying mechanisms of this spread are poorly understood. Although AD is conventionally considered a disease of the gray matter, it is also associated with pronounced and progressive deterioration of the white matter (WM). A link between abnormal tau and WM degeneration is suggested by findings from both animal and postmortem studies, but few studies demonstrated their interplay in vivo. Recent advances in diffusion magnetic resonance imaging and the availability of tau positron emission tomography (PET) have made it possible to evaluate the association of tau and WM degeneration (tau-WM) in vivo. In this study, we explored the spatial pattern of tau-WM associations across the whole brain to evaluate the hypothesis that tau deposition is associated with WM microstructural alterations not only in isolated tracts, but in continuous structural connections in a stereotypic pattern. Sixty-two participants, including 22 cognitively normal subjects, 22 individuals with subjective cognitive decline, and 18 with mild cognitive impairment were included in the study. WM characteristics were inferred by classic diffusion tensor imaging (DTI) and a complementary diffusion compartment model - neurite orientation dispersion and density imaging (NODDI) that provides a proxy for axonal density. A data-driven iterative searching (DDIS) approach, coupled with whole-brain graph theory analyses, was developed to continuously track tau-WM association patterns. Without applying prior knowledge of the tau spread, we observed a distinct spatial pattern that resembled the typical propagation of tau pathology in AD. Such association pattern was not observed between diffusion and amyloid-β PET signal. Tau-related WM degeneration is characterized by an increase in the mean diffusivity (with a dominant change in the radial direction) and a decrease in the intra-axonal volume fraction. These findings suggest that cortical tau deposition (as measured in tau PET) is associated with a lower axonal packing density and greater diffusion freedom. In conclusion, our in vivo findings using a data-driven method on cross-sectional data underline the important role of WM alterations in the AD pathological cascade with an association pattern similar to the postmortem Braak staging of AD. Future studies will focus on longitudinal analyses to provide in vivo evidence of tau pathology spreads along neuroanatomically connected brain areas
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