Latest ArticlesThe horizontal flow anaerobic digester indicated that high ammonia (2923 mg/L) and SO42- (3653 mg/L) would influence the performance of methane production with food waste as substrates. Therefore, bottle anaerobic digestion reactors were carried out to investigate the effect of ammonia/sulfate concentrations on the methane production. Experimental results manifested that the anaerobic digesters with an ammonia concentration of 3500 mg/L or sulfate of 1600 mg/L showed the best performance of methane production, with an average methane yield of 0.32 and 0.33 L (g VS)-1 d-1, respectively. Specifically, a higher ammonia (6500 mg/L) or sulfate (1600-3500 mg/L) level hindered the bioconversion of C from liquid to gas phase (2.68% or 1.73% CH4-Gas, respectively), while insignificantly for the hydrolyzation of C and N from solid to liquid phase. Similar to sulfate, high ammonia nitrogen seriously inhibited the methanation process, leading to a significant carbon accumulation in the anaerobic reactor, especially for propionic acid. The predominant archaea Methanosarcina at genus level indicated that aceticlastic methanogenesis was the major methanogenic pathway. Meanwhile, high ammonia level suppressed the activity of Methanosarcina, while modest sulfate improved H2-consuming methanogens activity. A large fraction of unclassified bacteria within the Firmicutes (43.78%-63.17%) and Bacteroidetes (24.20%-33.30%) phylum played an important role in substrates hydrolysis.
Developing the high activity, low cost and robust large-current-density-based electrocatalysts is of great significance for the industrial electrolytic water splitting. However, the current range of most reported materials is small, which makes it difficult for them to play their roles in practical applications. Here, a self-supported amorphous FexNi1-xMoO4/IF treated with ammonium fluoride (AF0.1-FNMO/IF) is synthesized by one-step hydrothermal method. With the help of NH4F, AF0.1-FNMO/IF exhibits a vertically cross-linked nanosheet with spherical structure. Electrochemical measurement shows that AF0.1-FNMO/IF affords a large current density ordeal and only need low overpotentials of 289 and 345 mV to reach a current response of 500 mA/cm2 for oxygen evolution reaction and hydrogen evolution reaction, respectively, together with long-time stability (both at 500, 1000 and 2000 mA/cm2) in 1.0 mol/L KOH solution. Using it as bifunctional catalyst for overall water splitting, the current densities of 100, 500, 1000 and 1500 mA/cm2 are achieved at a cell voltage of 1.71, 1.88, 1.94 and 1.97 V with excellent durability, which is much better than that of most published electrodes. The work provides valuable insight for designing higher activity nickel iron-based molybdate catalysts with large current density.
A series of DL-serine covalently modified multinuclear lanthanide implanted arsenotungstates K2[{Ln(H2O)7}2{As4W44O137(OH)18(H2O)2(DL-Ser)2}{Ln2(H2O)5(DL-Ser)}2]·65H2O (DL-Ser = DL-serine, Ln = La (1), Ce (2), Pr (3)) are obtained. Crystal structure analysis shows that these compounds are isomorphic and contain the basic [{As4W44O137(OH)18(H2O)2(DL-Ser)2}{Ln2(H2O)5(DL-Ser)}2]8– polyoxoanion constituted by two {As2W19O59(OH)8(H2O)}6‒ subunits, a [W6O23(OH)2(DL-Ser)2]14‒ fragment, and two embedded [Ln2(H2O)5(DL-Ser)]5+ groups, which further build into one dimensional linear chainlike structure via two peripheral Ln3+ ions. Most remarkably, these compounds exhibit rapid photochromic behaviors, which changed color quickly from white (1), yellow (2), green (3) to blue (1), brown (2) and glaucous (3) in ten minutes under UV irradiation, and that the colors gradually recovered in the dark for approximately 22 h.
Exosome and inclusive cargoes have manifested significant function in different biological events. In particular, glycopeptides in exosome are closely associated with occurrence and development of various diseases. Developing advanced tools is highly desired to enrich glycopeptides from exosomes, and enrich exosomes from complex biological samples as well. In this work, integration of L-cysteine and titania onto the surface of magnetic nanoparticles is designed to realize the coefficient affinity towards exosomes and inclusive glycopeptides. Benefiting from the synergistic affinity, we separate exosomes from human urine concentrate directly, which was proved by the detection of three typical antigen markers of exosomes. Furthermore, hardly any exosomes remained on materials after ultrasonication, which confirmed the good capture performance of Fe3O4@TiO2@L-Cys and high release effect of direct lysis. Moreover, 146 glycopeptides corresponding to 77 glycoproteins were successfully identified from captured exosomes. These satisfactory results will inspire more efforts to be devoted to this field and will be extremely helpful to in-depth information excavation of biological markers, especially disease-related ones, through exosomes and inclusive glycopeptides.
Screening of foodborne pathogens is important to prevent contaminated foods from their supply chains. In this study, a portable detection device was developed for rapid, sensitive and simple detection of viable Salmonella using a finger-actuated microfluidic chip and an improved recombinase aided amplification (RAA) assay. Improved propidium monoazide (PMAxx) was combined with RAA to enable this device to distinguish viable bacteria from dead ones. The modification of PMAxx into dead bacteria, the magnetic extraction of nucleic acids from viable bacteria and the RAA detection of extracted nucleic acids were performed using the microfluidic chip on its supporting device by finger press-release operations. The fluorescent signal resulting from RAA amplification of the nucleic acids was collected using a USB camera and analyzed using a self-developed smartphone App to quantitatively determine the bacterial concentration. This device could detect Salmonella typhimurium in spiked chicken meats from 1.3 × 102 CFU/mL to 1.3 × 107 CFU/mL in 2 h with a lower detection limit of 130 CFU/mL, and has shown its potential for on-site detection of foodborne pathogens.
The polysulfide shuttle limits the development of lithium-sulfur (Li-S) batteries with high energy density and long lifespan. Herein, nitrogen doped hollow carbon nanospheres (NHCS) derived from polymerization of dopamine on SiO2 nanospheres are employed to modify the commercial polypropylene/polyethylene/polypropylene tri-layer separators (PP/PE/PP@NHCS). The abundant nitrogen heteroatoms in NHCS exhibit strong chemical adsorption toward polysulfides, which can effectively suppress the lithium polysulfides shuttle and further enhance the utilization of active sulfur. Lithium-sulfur batteries employing the PP/PE/PP@NHCS deliver an initial discharge capacity of 1355 mAh/g and retain high capacity of 921 mAh/g after 100 cycles at 0.2 C. At a high rate of 2 C, the lithium-sulfur batteries exhibit capacity of 461 mAh/g after 1000 cycles with a capacity fading rate of 0.049% per cycle. This work demonstrates that the NHCS coated PP/PE/PP separator is promising for future commercial applications of lithium-sulfur batteries with improved electrochemical performances.
The freshness of seafood can be judged by detecting the concentration of triethylamine (TEA). In this work, 2D CuO porous nanosheets (CuO PNs) were prepared by a graphene oxide template method and their particle sizes were regulated by changing the calcination temperature. Their structure, morphology and gas sensing performances were investigated by various characterization methods. The response (Rg/Ra) of the gas sensor based on CuO PNs calcined at 700 ℃ was as high as 440-100 ppm TEA at the operating temperature of 40 ℃. The detection limit was as low as 0.25 ppm. In addition, the gas sensor has good selectivity and stability. The excellent TEA sensitivity is mainly resulted from the appropriate particle size and loose porous framework. This work not only paves the way to explore the novel low temperature TEA gas sensors, but also provides deep insight on improving the structure and properties of gas sensitive materials by controlling the calcination temperature.
Defect-rich, highly porous two-dimensional carbon nanosheets (CNS) have attracted tremendous research interests in catalysis and environmental purification and other fields, because of their unique micromorphology, chemical stability and high specific surface area. Herein, in this work, we report a new solution to synthesize an ultrathin two-dimensional CNS with rich defects and abundant pores via two-step etching the Ti3AlC2 with the help of I2 and NaOH. The CNS thickness, specific surface area and pore volume could be all tunable by adding the amount of I2. And the highest specific surface area and pore volume of the synthesized 2D CNS can be achieved 1134.4 m2/g and 0.80 cm3/g, with a thickness of only 0.64 nm and a yield of 35.9%. When employed as the anodes for lithium-ion batteries, the synthesized CNS anodes exhibit good cycling and rate capabilities. This work provides a novel and facile strategy for synthesizing highly porous and defective 2D carbon materials with good lithium storage properties.
Lithium dendrite growth due to uneven electrodeposition usually leads to the potential hazard of internal short circuit and shorter lifetime of lithium-based batteries. Extensive efforts have been devoted to explore the effects of single or two factors on dendrite growth, involving the diffusion coefficient, exchange current density, electrolyte concentration, temperature, and applied voltage. However, these factors interrelate during battery operation, signifying that a understanding of how they jointly influence the electrodeposition is of paramount importance for the effective suppression of dendrites. Here, we incorporate the dependent relationships among key factors into the phase-field model to capture their synergistic effects on electrodeposition. All the simulations are implemented in our self-written MATLAB code under a unified modeling framework. Following this, five groups of experimentally common dendrite patterns are reproduced and the corresponding electrodeposition driving forces are identified. Unexpectedly, we find that with the decrease of the ratio of exchange current density (or applied voltage) to diffusion coefficient, the electrodeposition morphology changes from needle-like dendrites to columnar dendrites and to uniform deposition. The present phase-field simulation tends to depict the practical electrodeposition process, providing important insights into synergistic regulation to suppress dendrite growth.
A facile and environmentally friendly visible-light-induced three-component reaction of α-diazoesters, cyclic ethers and NaSCN to construct organic thiocyanates has been developed at room temperature. This reaction could occur under photocatalyst- and additive-free conditions to afford a number of organic thiocyanates with moderate to good yield and favorable functional group tolerance.
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