Receptors from distant species may have conserved functions despite significant differences in protein sequences. Whereas the noncritical residues are often changed in distant species, the amino ...acids critical in receptor functions are often conserved. Studying the conserved residues between receptors from distant species offers valuable information to probe the roles of residues in receptor function. We identified two zebrafish receptors (zGPR81-1 and zGPR81-2) that show approximately 60% identity to human GPR81, GPR109a, and GPR109b but respond only to l-lactate and not to the GPR109a ligands. Protein sequence comparison among zebrafish GPR81s, mammalian GPR81s, GPR109a, and GPR109b identified a common structure (six Cys residues at the extracellular domains that potentially form three disulfide bonds) in this subfamily of receptors. In addition, a number of residues conserved in all GPR81s but not in GPR109s have been identified. Furthermore, we identified a conserved motif, C165-E166-S167-F168, at the second extracellular loop of GPR81. Using site-directed mutagenesis, we showed that Arg71 at the transmembrane domain 2 is very critical for GPR81 function. In addition, we demonstrated that the C165-E166-S167-F168 motif at the second extracellular loop is critical for GPR81 function, and the conserved six Cys residues at the extracellular regions are necessary for GPR81 function. It is important to mention that for those residues important for GPR81 function, the corresponding residues or motifs in GPR109a are also critical for GPR109a function. These findings help us better understand the interaction between lactate and GPR81 and provide useful information for GPR81 ligand design.
•SiGe porous nanorod arrays were synthesized via template-assisted method.•The SiGe porous nanorod arrays were used as anode materials of Li-ion batteries.•The SiGe porous nanorod arrays show better ...performance than planar electrode.•The porous structure and addition of Ge is responsible for the good performance.
We demonstrate the synthesis of SiGe porous nanorod arrays by using ZnO nanorod arrays as a sacrificial template. A seed-assisted method was employed to synthesize ZnO nanorod arrays which were coated by SiGe layer via a co-sputtering method. After the removal of ZnO nanorod, SiGe porous nanorod arrays were achieved. When used as an anode material of lithium-ion batteries, SiGe porous nanorod arrays showed enhanced performance compared to corresponding planar electrode and bare Si porous nanorod arrays. The good contact and adhesion of the porous nanorod arrays with the current collector, and the integration of Ge that can greatly improve the conductivity and lithium-ion diffusivity in SiGe layer, may be responsible for the enhanced performance.
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We demonstrate the synthesis of three-dimensional Cu-Ge core-shell nanowire array electrodes by directly depositing Ge on the surface of pre-synthesized Cu nanowire arrays viaan rf-sputtering method. ...When used as anodes of lithium-ion batteries, the Cu-Ge nanowire arrays display a high capacity of 1419 mAh g super(-1) at 0.5 C after 40 cycles and 734 mAh g super(-1) at 60 C after 80 cycles, which is better than planar electrodes. The improved performance can be attributed to the good electrical contact, fast electron transport and good strain accommodation of the nanowire array electrodes. The effect of the thickness of Ge layer on the electrochemical performance of the three-dimensional electrodes has also been investigated.
► Large-scale synthesis of Si nanowire arrays (SiNA) on Ti substrate were achieved. ► The SiNA showed large reversible capacity and high initial Coulombic efficiency. ► The array nanostructures might ...be responsible for the improved performance.
We have demonstrated large-scale synthesis of Si nanowire arrays (SiNA) on Ti substrate and their application as high-performance anode of Li-ion batteries. SiNA were controllably synthesized through hot-filament chemical vapour deposition (HFCVD) using Au films of different thickness as a catalyst. We found that the thickness of the Au film based catalysts played important role in controlling the morphology of Si nanostructures. The thick Au layer (e.g., 50nm) resulted in the formation of the SiNA, while the thin Au layer (e.g., 5nm) led to the disordered Si nanowires. The as-synthesized SiNA exhibited large reversible capacity (3600mAhg−1) and high initial Coulombic efficiency (86.4%), which is much better than the disordered Si nanowires. The good contact and adhesion of SiNA with current collectors, as well as excellent strain accommodation might be responsible for the enhanced performance as anode of Li-ion batteries.
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Laser capture microdissection in combination with microarrays allows for the expression analysis of thousands of genes in selected cells. Here we describe single-cell gene expression profiling of CA1 ...neurons in the rat hippocampus using a combination of laser capture, T7 RNA amplification, and cDNA microarray analysis. Subsequent cluster analysis of the microarray data identified two different cell types: pyramidal neurons and an interneuron. Cluster analysis also revealed differences among the pyramidal neurons, indicating that even a single cell type in vivo is not a homogeneous population of cells at the gene expression level. Microarray data were confirmed by quantitative RT-PCR and in situ hybridization. We also report on the reproducibility and sensitivity of this combination of methods. Single-cell gene expression profiling offers a powerful tool to tackle the complexity of the mammalian brain.
A nanocomposite of multiwalled carbon nanotubes (MWCNTs) anchored with SnS2 nanosheets (NS) (SnS2 NS@MWCNTs coaxial nanocables) has been synthesized through a simple solution-based method at room ...temperature. The synthetic mechanism of these intriguing nanocomposites is proposed as electrostatic attraction between tin ions and MWCNTs, followed by the nucleation and two-dimensional growth of SnS2. The as-synthesized SnS2 NS@MWCNTs coaxial nanocables have been applied as anode materials for lithium-ion batteries, which show better lithium storage performance compared to pure SnS2 nanosheets and MWCNTs. The combination of MWCNTs that can hinder the agglomeration and enhance electronic conductivity of the active materials might be responsible for the enhanced cyclic performance.
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Single-crystalline, monodisperse copper sulfide nanocrystals with controlled sizes, shapes, and phases were successfully synthesized via a simple, low-cost, and environmentally friendly chemical ...reaction of CuCl2 and S in oleylamine at 100−180 °C. It was found that the molar ratios of CuCl2:S played the critical role for the control of the sizes, shapes, and phases of copper sulfide nanocrystals. The hexagonal CuS nanodisks, hexagonal CuS nanoribbons consisting of face-to-face stacked nanodisks, and monoclinic Cu1.75S nanoribbons consisting of face-to-face stacked nanodisks were obtained when the molar ratios of CuCl2:S were 1:1, 2:3, and 2:1, respectively. It was believed that the van der Waals force and dipole−dipole interaction were responsible for the self-assembly of copper sulfide nanodisks. Finally, the copper sulfide nanocrystals were characterized by transmission electron microscopy, high-resolution transmission electron micrscopy, X-ray diffraction, and Fourier transform infrared, and its growth mechanism was primarily discussed.
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This paper reports a new type of nanostructure, carbon nanotubes@SnO2@carbon (CNTs@SnO2@C) coaxial nanocables, by homogeneous deposition of SnO2 and carbon layers in sequence on CNTs templates. The ...CNTs@SnO2@C coaxial nanocables with carbon layers of different thickness have been prepared and applied as anode materials for lithium-ion batteries, which exhibit higher lithium storage capacities and better cycling performance compared to single CNTs and CNTs@SnO2 coaxial nanocables. This novel nanostructure, which integrates both electronic conductivity and buffering matrix design strategies, can be responsible for the improved lithium storage performance.
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This paper reports the synthesis of carbon-encapsulated Fe3O4, γ-Fe2O3, and Fe nanostructures using FeOOH as a precursor and carbon nanocapsules (CNCs) as nanoreactors via controllable thermal ...transformation processes. The magnetic property investigation reveals that the as-synthesized Fe3O4-CNCs, γ-Fe2O3-CNCs, and Fe-C nanostructures all exhibit ferromagnetic behavior with quite high saturation magnetizations. Moreover, the Fe3O4-CNCs with a controlled carbon coating are prepared and their comparative lithium storage properties are investigated. It is found that optimized Fe3O4-CNCs exhibit high capacity and good cycling performance.
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