Search

Herein, we demonstrate a Co/S doped TiO2 bimetal sulfur oxide nanoparticle catalyst (labeled CoTiOS) with heterovalent Co states and abundant oxygen vacancy (Ov) defects for the photocatalytic nitrogen reduction reaction (PNRR) in an ambient environment. Co/S co-doping converted TiO2 into a catalyst for visible light photocatalytic nitrogen fixation. The incorporation of Co endows TiO2 with better electrical conductivity and electron trapping ability. The introduction of sulfur adjusts the amount of Ov and Co3+/Co2+ ratio. Ov acts as an active site for trapping H2O and activating H2O to generate a proton for the N2 reduction reaction. Active atoms Co3+ were exposed and activated for N2, and electrons hopping between Co2+ and Co3+ enhanced electron transfer. CoTiOS-3 with appropriate Co/S doping has abundant Ov, suitable heterovalent Co3+/Co2+ ratios, higher surface active sites, smaller crystal sizes, higher specific surface area (SBET), and fast transfer of electrons, and it exhibited a super PNRR activity of 491.56 μmol g−1 h−1, an apparent quantum efficiency (AQE) of 1.89% at 420 nm and a solar-to-ammonia (STA) conversion efficiency of 0.083% in pure water under AM1.5G light irradiation. It also exhibited excellent stability and persistence and shows potential for photocatalytic nitrogen fixation. [ABSTRACT FROM AUTHOR]

A novel Ce/S co-doped TiO2 sulfur-oxide catalyst (labeled TiCeOS) with heterovalent metal states and oxygen-vacancy defects was synthesized for effective photocatalytic nitrogen fixation into ammonia under visible light. The hydrazine-driven TiCeOS-3 with an appropriate heterovalent Ce3+/Ce4+ state ratio and oxygen vacancies exhibited excellent photocatalytic nitrogen fixation activity of 382.4 μmol g−1 h−1 without a sacrificial agent and maintained stability. An apparent quantum efficiency (AQE) of 3.32% at 420 nm and a solar-to-ammonia (STA) conversion efficiency of 0.058% in pure water under AM1.5 G light irradiation were achieved. Synergistic transition metal Ce3+/4+-cation and S2−-anion co-doped TiO2 adjusted the energy bandgap to improve its utilization of visible light, where the ratio of Ce3+/Ce4+ was regulated via hydrazine to introduce oxygen vacancies to balance the charge and maintain the lattice electroneutrality. The oxygen vacancies act as active sites for trapping water molecules and activating the water molecules to generate protons for N2 reduction. The surface Ce3+ acts as active sites for adsorbed and activated N2, and the photoproduced electrons facilitate efficient electron transfer through electron hopping between Ce3+ and Ce4+ for N2 reduction. This study presents a novel approach to designing efficient catalysts for sustainable nitrogen fixation through a photocatalytic process. [ABSTRACT FROM AUTHOR]

Herein, we demonstrated S2− anion incorporation into BiVO4 for converting an oxidative-type BiVO4 photocatalyst into a reductive-type BiV(S,O)4−x (labeled BiVOS) sulfo-oxide photocatalyst for efficient N2 fixation under an ambient environment. BiVOS-2 not only exhibited the highest NH3 production rate of 563.6 μmol g−1 h−1 without sacrificial agents and with durable stability but also had an apparent quantum efficiency (AQE) of 2.18% at 420 nm and a solar-to-ammonia (STA) conversion efficiency of 0.071% in pure water under AM1.5G light irradiation. At the same time, the sulfur-free BiVO4 can't realize N2 to NH3 conversion. The S2− doping introduced Vo, which converted V5+ around Vo into V4+ to keep the electrical neutrality. The active atoms V4+ were exposed and activated N2, and the electron hopping between V5+ and V4+ improved electron transfer. Density functional theory (DFT) calculation indicates that S2− anion doping can enhance adsorption energy, elongate the N≡N bond of the adsorbed N2 molecule, and facilitate electron transfer to the antibonding orbital of the N2 molecule, leading the BiVOS sulfo-oxide catalyst to have excellent N2 fixation activity. This study provides a promising method for converting an oxidative-type catalyst into a reductive catalyst to extend material applications. [ABSTRACT FROM AUTHOR]

A novel nanocomposite (TNTs‐FeS) was developed by anchoring ferrous sulfide (FeS) nanoparticles immobilized on titanate nanotubes (TNTs) by hydrothermal method to remove U(VI) and Re(VII) from aqueous solution, and the removal mechanism and efficiency were examined. The experimental results showed that the TNTs can effectively improve the dispersibility and stability of FeS. The environmental conditions, including initial solution pH, initial concentration, equilibrium time, and dosage, played an important role in the remediation process, which can affect the immobilization efficiency significantly. The maximum quantity removal of U(VI) and Re(VII) was 291.67 and 226.23 mg/g at pH of 6.0 and 12.0. The adsorption kinetics and the equilibrium isotherms of U(VI) and Re(VII) all fitted well with the pseudo‐second‐order model (R2>0.99) and the Freundlich model (R2>0.99). The main mechanism of removal by TNTs‐FeS was electrostatic attraction, chemical reduction, and surface complexation. Thus, TNTs‐FeS composites exhibited a high potential to remove U(VI) and Re(VII) heavy metal ions from the surface and groundwater. [ABSTRACT FROM AUTHOR]

Borrelia burgdorferi as a causative agent of Lyme disease is transmitted by Ixodes spp. ticks to humans and animals. Sheep is considered a natural reservoir for B. burgdorferi and plays a pivotal role in disease transmission and the expansion of natural foci. An epidemiological investigation of B. burgdorferi in sheep is essential for prevention and control of Lyme disease. In this study, we developed a recombinant outer surface protein C (OspC)-based ELISA for serological study of B. burgdorferi in sheep with a specificity and sensitivity of 84.4% and 86.2%, respectively. A total of 972 collected serum samples from the Northeast China regions in 2015 and 2016 were determined with positive rates of 5.8% and 12.2%, respectively. Thus, specific pathogen-free sheep were infected with B. burgdorferi SZ strain to study on the secretion of specificity antibody against OspC. It revealed that specific antibody was detected on day 5 postinoculation and sustained in a high level for ∼28 days, the peak occurred at ∼13 days. Taken together, the result indicated that the established ELISA is capable for clinical diagnosis and epidemiological study on B. burgdorferi in sheep at the early stage of infection and detecting the specific antibody during the secretion period. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a new clustering algorithm called UDSC for uncertain data stream. According to the existence probability of cluster, clusters are divided into three levels: strong, transitional and weak. An effective strategy for choosing candidate cluster is developed based on four factors: distance, cluster compactness, existence probability of cluster and existence strength of cluster, which used to find optimal accepted cluster for each continuously arriving data. Then we proposed several rules to describe drifts and shifts in clusters, which used to help users known the changes clearly in clusters and help users make new decisions accurately. Experiment results shows that UDSC clustering algorithm outperforms the existing methods in efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

Borrelia burgdorferi as a causative agent of Lyme disease is transmitted by Ixodes spp. ticks to humans and animals. Sheep is considered a natural reservoir for B. burgdorferi and plays a pivotal role in disease transmission and the expansion of natural foci. An epidemiological investigation of B. burgdorferi in sheep is essential for prevention and control of Lyme disease. In this study, we developed a recombinant outer surface protein C (OspC)-based ELISA for serological study of B. burgdorferi in sheep with a specificity and sensitivity of 84.4% and 86.2%, respectively. A total of 972 collected serum samples from the Northeast China regions in 2015 and 2016 were determined with positive rates of 5.8% and 12.2%, respectively. Thus, specific pathogen-free sheep were infected with B. burgdorferi SZ strain to study on the secretion of specificity antibody against OspC. It revealed that specific antibody was detected on day 5 postinoculation and sustained in a high level for ∼28 days, the peak occurred at ∼13 days. Taken together, the result indicated that the established ELISA is capable for clinical diagnosis and epidemiological study on B. burgdorferi in sheep at the early stage of infection and detecting the specific antibody during the secretion period.