Antibiotic resistance genes (ARGs) are emerging environmental contaminants and pose a threat to public health. In this study, four tetracycline resistance genes (tetM, tetO, tetQ and tetW) and two ...sulfonamide resistance genes (sulI and sulII) were evaluated in 4 municipal wastewater and 8 rural domestic sewage treatment systems with different wastewater handling abilities and treatment processes using quantitative polymerase chain reaction (qPCR). In the influents, the relative abundance of different ARGs showed significant variations among the sampling sites. In addition, significant correlations (tetQ: R2=0.712, P<0.05; tetO: R2=0.394, P<0.05) between the gene copy numbers and wastewater-receiving capacity were observed. Statistical analysis revealed a positive correlation (R2=0.756, P<0.05) between the gene copy numbers of sulI and intI1, whereas the gene numbers of tetM and sulI were strongly correlated with 16S rDNA. Significant reductions (1–3 orders of magnitude) in ARGs were observed in municipal wastewater treatment systems, but a smaller reduction was found in the rural domestic sewage treatment systems. These results provide insights into the occurrence and removal of ARGs in wastewater treatment systems in both rural and urban areas in eastern China.
► We evaluated ARG removal in municipal and rural domestic sewage treatment systems. ► The abundance of ARGs showed significant variation among the sampling sites. ► The tetQ gene number was correlated with wastewater-receiving capacity. ► Higher removal rate of tet genes was found in municipal sewage treatment systems. ► The constructed wetland with plants may play a major role in the removal of ARGs.
This study aimed at quantifying the concentration and removal of antibiotic resistance genes (ARGs) in three municipal wastewater treatment plants (WWTPs) employing different advanced treatment ...systems biological aerated filter, constructed wetland, and ultraviolet (UV) disinfection. The concentrations of tetM, tetO, tetQ, tetW, sulI, sulII, intI1, and 16S rDNA genes were examined in wastewater and biosolid samples. In municipal WWTPs, ARG reductions of 1–3 orders of magnitude were observed, and no difference was found among the three municipal WWTPs with different treatment processes (p > 0.05). In advanced treatment systems, 1–3 orders of magnitude of reductions in ARGs were observed in constructed wetlands, 0.6–1.2 orders of magnitude of reductions in ARGs were observed in the biological aerated filter, but no apparent decrease by UV disinfection was observed. A significant difference was found between constructed wetlands and biological filter (p < 0.05) and between constructed wetlands and UV disinfection (p < 0.05). In the constructed wetlands, significant correlations were observed in the removal of ARGs and 16S rDNA genes (R 2 = 0.391–0.866; p < 0.05). Constructed wetlands not only have the comparable ARG removal values with WWTP (p > 0.05) but also have the advantage in ARG relative abundance removal, and it should be given priority to be an advanced treatment system for further ARG attenuation from WWTP.
In this study, an efficient and cheap electrocatalysts are prepared by a simple synthetic method for oxygen evolution reaction (OER) hydrogen evolution reaction (HER). Nickel/nickel ...oxide@3dimensional hierarchical porous graphene (Ni-NiO@3DHPG) and cobalt/cobalt oxide@3dimensional hierarchical porous graphene (Co-CoO@3DHPG) electrocatalysts were obtained from cation exchange resin, nickel acetate and cobalt nitrate as a source of carbon, Ni and Co respectively. In Ni-NiO@3DHPG and Co-CoO@3DHPG, metal and metal oxide nanoparticles embedded in the graphene layers, were confirmed by different techniques. The 3-D graphene in Ni-NiO@3DHPG and Co-CoO@3DHPG were thinned wall and highly porous structure and large specific surface area. The Ni-NiO@3DHPG composite displays onset potential, overpotential (10 mA cm−2) and Tafel value of are 1.53 V, 1.64 V and 55 mV dec−1 for OER and −0.18 V, −0.31 V and 78 mV dec−1 for HER respectively. Similarly, Co-CoO@3DHPG catalyst show onset potential, overpotential (10 mA cm−2) and Tafel are 1.59 V, 1.68 V and 65 mV dec−1 for OER and −0.26 V, −0.40 V and 85 mV dec−1 for HER respectively. Electrocatalysts show good stability after 4 h continuously. This simple synthetic method will open a new way for cheap and efficient electrocatalysts of other types of non-precious metals for OER and HER.
A simple method was used to in situ grown Ni-NiO and Co-CoO in three dimensional hierarchical porous graphene by ion exchange/activation method. The obtained Ni-NiO@3DHPG and Co-CoO@3DHPG show efficient performance for OER and HER. the better performance of Ni-NiO@3DHPG and Co-CoO@3DHPG are due to well dispersion of Ni-NiO and Co-CoO particle in graphene layers and high conductivity of graphene layer which facilitate fast transport of electron. Display omitted
•- A novel and less toxic alternative precursor to synthesize 3DHPG.•Ni-NiO@3DHPG and Co-CoO@3DHPG active and stable electrocatalyst for OER and HER.•The efficient activities attributed to Ni-NiO and Co-CoO and condutive graphene.
► Mixture of sludge and food waste were fermented to obtain VFAs. ► VFA production and VFAs/SCOD ratio was the highest at an initial pH of 9.0. ► The fermentation liquid at pH 9.0 was a suitable ...carbon source for PHA biosynthesis. ► Continuous pulsed feeding had the highest PHA synthesis rate of 64.5%.
The combined fermentation of sludge from the secondary sedimentation tank of municipal wastewater treatment plants and food waste enables not only waste reduction, but also the acquisition of volatile fatty acids (VFAs) for the biosynthesis of polyhydroxyalkanoates (PHAs). To better understand variables influencing the production of VFAs and PHAs, this study considered anaerobic fermentation of VFAs under different pH conditions. The production of VFA was the highest at an initial pH of 9.0, reaching 25,934±1,485mgCOD/L and a VFAs/SCOD ratio of 0.61±0.04. When the fermentation liquid was used as a carbon source for PHA biosynthesis, continuous pulsed feeding resulted in the highest PHA synthesis rate of 64.5±1.8%, while the culture receiving a one-time feeding had the lowest rate of only 51.5±2.0%.
► Nickel nanocrystals can be well-dispersed and deposited on carbon nanotubes (MWCNTs) by using chemical vapor deposition (CVD) method without adding other reducing agent. ► No other additives, ...Ni@Pd/MWCNTs nanosized catalysts can be synthesized by using replacement method. ► The electrocatalytic activity of ethanol oxidation on Ni@Pd/MWCNTs is 2.3 times higher than that of Pd/MWCNTs electrocatalyst.
Ni@Pd nanoparticles with core/shell structure uniformly dispersed on multi-walled carbon nanotubes (Ni@Pd/MWCNTs) is successfully prepared via a two-step strategy: impregnation–reduction method and replacement method. The Ni@Pd/MWCNTs composite was characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. It shows a uniform dispersion of Ni@Pd nanoparticles with core/shell structure on MWCNTs with the average particle size of 3.4nm. The Ni@Pd/MWCNTs composite was used as electrocatalyst for alcohol oxidation in alkaline media for fuel cells. The electrocatalytic activity of ethanol oxidation on Ni@Pd/MWCNTs is 2.3 times higher than that of Pd/MWCNTs electrocatalyst at the same Pd loadings. The enhanced electrocatalytic properties could be attributed to not only the electric synergistic effect between Pd and Ni, but also the high use ratio of Pd for its shell structure.
To accurately extract cultivated land boundaries based on high-resolution remote sensing imagery, an improved watershed segmentation algorithm was proposed herein based on a combination of pre- and ...post-improvement procedures. Image contrast enhancement was used as the pre-improvement, while the color distance of the Commission Internationale de l´Eclairage (CIE) color space, including the Lab and Luv, was used as the regional similarity measure for region merging as the post-improvement. Furthermore, the area relative error criterion (δA), the pixel quantity error criterion (δP), and the consistency criterion (Khat) were used for evaluating the image segmentation accuracy. The region merging in Red–Green–Blue (RGB) color space was selected to compare the proposed algorithm by extracting cultivated land boundaries. The validation experiments were performed using a subset of Chinese Gaofen-2 (GF-2) remote sensing image with a coverage area of 0.12 km2. The results showed the following: (1) The contrast-enhanced image exhibited an obvious gain in terms of improving the image segmentation effect and time efficiency using the improved algorithm. The time efficiency increased by 10.31%, 60.00%, and 40.28%, respectively, in the RGB, Lab, and Luv color spaces. (2) The optimal segmentation and merging scale parameters in the RGB, Lab, and Luv color spaces were C for minimum areas of 2000, 1900, and 2000, and D for a color difference of 1000, 40, and 40. (3) The algorithm improved the time efficiency of cultivated land boundary extraction in the Lab and Luv color spaces by 35.16% and 29.58%, respectively, compared to the RGB color space. The extraction accuracy was compared to the RGB color space using the δA, δP, and Khat, that were improved by 76.92%, 62.01%, and 16.83%, respectively, in the Lab color space, while they were 55.79%, 49.67%, and 13.42% in the Luv color space. (4) Through the visual comparison, time efficiency, and segmentation accuracy, the comprehensive extraction effect using the proposed algorithm was obviously better than that of RGB color-based space algorithm. The established accuracy evaluation indicators were also proven to be consistent with the visual evaluation. (5) The proposed method has a satisfying transferability by a wider test area with a coverage area of 1 km2. In addition, the proposed method, based on the image contrast enhancement, was to perform the region merging in the CIE color space according to the simulated immersion watershed segmentation results. It is a useful attempt for the watershed segmentation algorithm to extract cultivated land boundaries, which provides a reference for enhancing the watershed algorithm.
China, being a densely populated nation, faces a substantial economic burden due to a high incidence of lupus nephritis (LN) cases. The concealed onset of LN has resulted in many individuals have ...missed the optimal timing for treatment. The aim of the research is to study the serum metabolomics of Chinese LN patients using gas chromatography (GC)/mass spectrometry (MS) and liquid chromatography (LC)/MS to identify potential diagnostic markers. Fifty LN patients and fifty normal controls, matched for Body Mass Index (BMI) and age, were selected. Serum analysis was conducted using GC/MS and LC/MS, followed by multivariate statistical analysis. Various multidimensional analyses, including principal component analysis, partial least squares discrimination analysis, and orthogonal partial least squares discrimination analysis, along with one-dimensional analyses such as t-tests, were performed. Metabolites with variable importance in projection value > 1 and a p-value < 0.05 were considered critical biomarkers for LN. Furthermore, identified biomarkers delineated relevant metabolic pathways, and a metabolic pathway map was obtained from the database. Forty-one metabolites were identified as potential LN biomarkers, primarily associated with immune regulation, energy metabolism, intestinal microbial metabolism, renal damage, and oxidative stress. The potential for diagnosing LN and other diseases through metabolomics is demonstrated. Future research should explore larger sample sizes, metabolomic comparisons across different diseases and health states, and integration of metabolomics with clinical diagnostics. Such studies will enhance the understanding of metabolomics in medical diagnosis and provide robust support for its practical application.
Nitrogen doped porous graphite with trace iron and hollow spherical shape is synthesized by using glucose as carbon source, dopamine hydrochloride as N source, Fe(NO3)3 as Fe source and solid core ...mesoporous shell silica sphere as template. The glucose and dopamine is carbonized to N-doped carbon; the silica template produces porous and hollow shape with much edges or intrinsic defects; and the addition of Fe increases pore diameter, graphitization degree, total N and pyridinic N content. The characterizations confirm that the doping N leads to active sites for oxygen reduction reaction; the Fe forms active NFe species yet electrochemically unstable, which is removed at last. The intrinsic graphite defect and its synergistic effect with doping N are also believed to favor ORR. The material with the above features corresponds to superior oxygen reduction activity in both alkaline and acidic media to commercial Pt/C. The as-synthesized material with few Fe also shows excellent stability due to the graphitized matrix and little metal with excellent anti-methanol and anti-CO performances. The durability of catalysts is also confirmed by using graphite as counter electrode to exclude the impact of dissolution of Pt counter electrode and its re-deposition on the working electrode.
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•Mesoporous silica template is adopted to get nitrogen doped mesoporous carbon.•Fe improves pore size, graphitization degree, total N and pyridinic N content.•Fe-N is active to ORR yet unstable which need to be removed.•The above features lead to higher ORR activity and stability than Pt/C.
Novel and hollow-structured bimetallic oxide (NiCo2O4) anchored on nitrogen-doped graphene (NG) has been manufactured by a hydrothermal-calcination method. The ultrafine hollow-structured NiCo2O4 ...nanorod can be dexterously grafted on an N-doped graphene surface (NiCo2O4/NG) by regulating the alkali sources. The obtained NiCo2O4/NG composite shows much larger specific capacitance and stability according to the cyclic voltammetry (CV) measurements and galvanostatic charge-discharge (GCD) examinations. The electrochemical measurements show that NiCo2O4/NG-H3 composite exhibited a high specific capacitance of 2147.4 F g−1 at 1 A g−1, as well as perfect cycling stability (93.7% capacitance retention after 2000 cycles), indicating a potential application in electrochemical supercapacitors. The XPS spectra of NiCo2O4/NG-H3 further reveal that the excellent performance should be attributed to the electron-donating (synergistic effect) between NiCo2O4 and NG.
•The hollow-structured NiCo2O4 nanorods deposited on the surface can significantly boost electron transport.•The modified 3D graphene with nitrogen enhances the content of the active sites and surface area on the nanorods.•Excellent electron-donating of NiCo2O4 to NG greatly improves the specific capacitance of the NiCo2O4/NG composite.•NiCo2O4/NG composite exhibits a high specific capacitance and an excellent cycling stability.
Here we report a simple one-pot microwave-polyol reduced method to anchor platinum nanoparticles on graphene with the aid of poly (diallyldimethylammonium chloride) (PDDA), forming a Pt/PDDA–G hybrid ...(Pt/PDDA–G). High Pt metal loadings, up to 85 wt.% with a mean size of 1.4 nm, were densely in situ decorated on PDDA-modified graphene surfaces. The electrochemical tests showed that the activity and stability of Pt supported on PDDA–graphene hybrid substrates for methanol oxidation were better than that of Pt supported on graphene sheets, also better than the widely used Pt/carbon black electrocatalysts with the same Pt content on the electrode. This improved activity indicates that PDDA plays a crucial role in the highly dispersion and stabilization of Pt nanoparticles on graphene and PDDA–G are able to an alternative support for Pt immobilization in direct methanol fuel cells.
•Pt nanoparticles were deposited on diallyldimethylammonium chloride modified graphene oxide.•High Pt metal loadings, up to 85 wt. % with a mean size of 1.4 nm, were in situ decorated on PDDA-graphene surfaces.•PDDA functionalized graphene provided the higher electrochemical active surface area.•Surface area and size of modified catalysts explain the improved electroactivity and the stability.
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