65 research outputs found

    Bacterial Diversity in Linglong Gold Mine, China

    No full text
    <p>Bacteria have been actively regulating cycles of various elements in the environment. To explore the potential bacterial role in gold biogeochemical cycling, this study analyzed the bacterial diversity of mine rock (MR) and surface soil (SS) samples from Linglong gold mine using 16S rRNA gene clone library analysis and cultivation method. From MR, 24 operational taxonomic units (OTUs) were identified from MR, covering 3 phyla and 18 genera. Meanwhile, 24 OTUs were identified from SS, including 4 phyla and 18 genera. Compared with 16S rRNA gene clone library analysis, 28 aerobic and 34 anaerobic isolates were obtained, whereas 26 aerobic and 71 anaerobic strains were isolated from SS. The cultivable bacteria were affiliated with Firmicutes, Proteobacteria and Actinobacteria phyla, and dominated by Firmicutes. These results underscore the high level of bacterial diversity in the gold mine. Our study provides information on the microbial diversity in Linglong gold mine and sheds light on the existence and potential function of bacteria in the gold biogeochemical cycling.</p

    Synthesis and Self-Assembly Behavior of Charged Au Nanocrystals in Aqueous Solution

    No full text
    A series of water-soluble Au nanocrystals with different core sizes coated by either negatively or positively charged ligands are synthesized. We find a ligand interexchange process takes place when positively and negatively charged nanocrystals are mixed together and heated, resulting in mixed charged zwitterionic nanocrystals. The ligand exchange process between nanocrystals is studied in detail by electrophoresis. Self-assembly properties of the monocharged and zwitterionic nanocrystals are studied subsequently. By using the solvent evaporation process only the zwitterionic and positively charged nanocrystals can pack into well-ordered fcc lattice films. Under the nonsolvent diffusion condition, only the zwitterionic nanocrystals can aggregate and form shaped supracrystals. Structural analysis shows that the interparticle distance of the shaped supracrystal made of zwitterionic nanocrystals is 1 nm larger than that of the film one. The different interparticle distance is ascribed to the different fabrication process. We consider that nanocrystals adopt the closest packing in the film supracrystal due to the destroyed electrical double layer during the drying process, while the electrostatic repulsion plays an important role in determining the interparticle distance in the shaped supracrystal

    Antimony Redox Biotransformation in the Subsurface: Effect of Indigenous Sb(V) Respiring Microbiota

    No full text
    Anaerobic microbiological antimonate [Sb­(V)] respiration is a newly discovered process regulating the Sb redox transformation in soils. However, little is known about the role microbiological Sb­(V) respiration plays in the fate of Sb in the subsurface, especially in the presence of sulfate and electron shuttles. Herein, we successfully enriched a Sb­(V) reducing microbiota (SbRM) from the subsurface near an active Sb mine. SbRM was dominated by genus <i>Alkaliphilus</i> (18–36%), <i>Clostridiaceae</i> (17–18%), <i>Tissierella</i> (24–27%), and <i>Lysinibacillus</i> (16–37%). The incubation results showed that SbRM reduced 88% of dissolved Sb­(V) to Sb­(III), but the total Sb mobility remained the same as in the abiotic control, indicating that SbRM alone did not increase the total Sb release but regulated the Sb speciation in the subsurface. Micro X-ray fluorescence (μ-XRF) analysis suggested the association of Sb and Fe, and electron shuttles such as anthraquinone-2,6-disulfonic disodium salt (AQDS) markedly enhanced the Sb release due to its ability to facilitate Fe mineral dissolution. Sb L-edge and S K-edge X-ray absorption near edge structure (XANES) results demonstrated that indigenous SbRM immobilized Sb via Sb<sub>2</sub>S<sub>3</sub> formation, especially in a sulfur-rich environment. The insights gained from this study shed new light on Sb mobilization and its risk assessment in the subsurface environment

    Co<sub>2</sub>Cu<sub>1</sub>Ce<sub><i>y</i></sub>O<sub><i>x</i></sub> Mixed Metal Oxide Nanoparticles with Oxygen Vacancies as Catalysts for Toluene Oxidation

    No full text
    A multimetal MOF (metal–organic framework), Ce­(III)/Co2Cu1-MOF-74, has here been synthesized in a simple and convenient manner by using the mechanical ball milling method. This method is both energy-saving and environmentally friendly. By using the obtained product compounds as a template, Co2Cu1CeyOx mixed metal oxides were prepared by calcination to serve as a catalyst for toluene catalytic oxidation. Co2Cu1CeyOx had the form of nanoparticles with a uniform morphology. As a result of the experiments, the conversion percentages of the Co2Cu1Ce0.75Ox catalyst in catalyzing the toluene oxidation reached 50% (T50) and 90% (T90) at the temperatures of 196 and 210 °C, respectively. The Co2Cu1Ce0.75Ox catalyst exhibited an abundance of multiphase interfaces and metal doping effects, which effectively induced an abundance of oxygen vacancies on the catalyst surface. Furthermore, the Co2Cu1Ce0.75Ox catalyst exhibited excellent durability within 24 h and demonstrated remarkable regenerative capabilities after steam-induced reduction by 5%. Thus, the use of MOFs as precursor compounds, which were mechanically synthesized in a green and rapid manner, helped to design high-efficiency multimetal mixed oxide nanoparticle catalysts with abundant multiphase interfaces, which could be used for toluene catalytic oxidation. This rendered possibilities for large-scale applications in related areas

    Controlled Hydrophobic Biosurface of Bacterial Cellulose Nanofibers through Self-Assembly of Natural Zein Protein

    No full text
    A novel, highly biocompatible bacterial cellulose (BC)-zein composite nanofiber with a controlled hydrophobic biosurface was successfully developed through a simple and green solution impregnation method, followed by evaporation-induced self-assembly (EISA) of adsorbed zein protein. The surface hydrophobicity of the zein-modified BC nanofibers could be controlled by simply changing the zein concentration, which is able to tune the morphology of self-assembled zein structures after EISA, thus affecting the surface roughness of composite membranes. Zein self-assembly at low concentrations (5 mg/mL) resulted in the formation of hierarchical zein structures (spheres and bicontinuous sponges) on the BC surface, thus increasing the surface roughness and leading to high hydrophobicity (the water contact angle reached 110.5°). However, at high zein concentrations, these large zein spheres assembled into a flat zein film, which decreased the surface roughness and hydrophobicity of membranes. The homogeneous incorporation of zein structures on the BC surface by hydrogen bonding did not significantly change the internal structure and mechanical performance of BC nanofibers. In comparison with pure BC, the BC-zein nanofibers had a better biocompatibility, showing a significantly increased adhesion and proliferation of fibroblast cells. This is probably due to the rough surface structure of BC-zein nanofibers as well as the high biocompatibility of natural zein protein. The novel BC-zein composite nanofibers with controlled surface roughness and hydrophobicity could be of particular interest for the design of BC-based biomaterials and biodevices that require specific surface properties and adhesion

    Mesoporous ZnS-Sb/C Reduced Graphene Oxide Nanostructures as Anode Materials for Sodium-Ion Batteries

    No full text
    Metal-based sulfides are favored by researchers because of their high theoretical capacity, but their inherent volume expansion problems limit their further applications. To address the above issues, we prepared ZnS-Sb@C@rGO core–shell nanosphere anode materials for high-performance sodium-ion batteries (SIBs). The ZnS-Sb heteromeric core with synergistic effects was designed to facilitate rapid electrolyte penetration and accelerate Na+ transformation kinetics. Meanwhile, the double coating of the outer carbon shell and rGO layer provides rich sodium embedding sites and improves the conductivity and charge transfer capability of the composite. Its unique layered heterogeneous structure design provides a lot of buffer space and effectively prevents the shedding of active substances. The composite has excellent electrochemical properties in sodium-ion batteries, with a high initial discharge specific capacity of 1117.1 mAh g–1 at 0.1 A g–1. The battery achieves a long cycle life, and the discharge specific capacity is 210.3 mAh g–1 after 300 cycles at 1 A g–1. This novel structural design may be one of the feasible solutions to achieve the excellent properties of SIB anode materials

    Solid-State NMR Shows That Dynamically Different Domains of Membrane Proteins Have Different Hydration Dependence

    No full text
    Hydration has a profound influence on the structure, dynamics, and functions of membrane and membrane-embedded proteins. So far the hydration response of molecular dynamics of membrane proteins in lipid bilayers is poorly understood. Here, we reveal different hydration dependence of the dynamics in dynamically different domains of membrane proteins by multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy using 121-residue integral diacylglycerol kinase (DAGK) in 1,2-dimyristoyl-<i>sn</i>-glycero-3-phosphocholine (DMPC)/1,2-dimyristoyl-<i>sn</i>-glycero-3-phospho-(1′-<i>rac</i>-glycerol) (DMPG) lipid bilayers as a model system. The highly mobile and immobile domains of DAGK and their water accessibilities are identified site-specifically by scalar- and dipolar-coupling based MAS ssNMR experiments, respectively. Our experiments reveal different hydration dependence of the dynamics in highly mobile and immobile domains of membrane proteins. We demonstrate that the fast, large-amplitude motions in highly mobile domains are not triggered until 20% hydration, enhanced at 20–50% hydration and unchanged at above 50% hydration. In contrast, motions on submicrosecond time scale of immobile residues are observed to be independent of the hydration levels in gel phase of lipids, and at the temperature near gel–liquid crystalline phase transition, amplitude of whole-molecule rotations around the bilayer normal is dominated by the fluidity of lipid bilayers, which is strongly hydration dependent. The hydration dependence of the dynamics of DAGK revealed by this study provides new insights into the correlations of hydration to dynamics and function of membrane proteins in lipid bilayers

    Effects of DFCs on cell sheet formation by HPDLSCs and PPDLSCs in vitro.

    No full text
    <p><b>A:</b> H&E staining of cell sheets. HPDLSCs formed more cell layers and ECM than PPDLSCs. In the co-cultured systems, both HPDLSCs and PPDLSCs formed more cell layers and ECM than in the monocultured systems (hematoxylin-eosin staining, magnification: 400×, scale bar = 50 mm). <b>B:</b> SEM of cell sheets; HPDLSCs secreted richer ECM than PPDLSCs, and co-culture with DFCs enhanced the ECM secretion by both HPDLSCs and PPDLSCs. Notes: DFCs (–), monocultured PDLSCs that were cultured with transwell containing no DFCs; DFCs (+), co-cultured PDLSCs that were cultured with transwells seeded with a specific number of DFCs.</p

    Isolation and identification of HPDLSCs, PPDLSCs, and DFCs.

    No full text
    <p><b>A:</b> Morphologies of DFCs, HPDLSCs, and PPDLSCs observed by microscopy. <b>B:</b> Mesenchymal stem cell phenotype examination by flow cytometric analysis.</p
    • …
    corecore