Search

The effective utilization of solar energy for hydrogen production requires an abundant supply of thermodynamically active photo-electrons; however, the photocatalysts are generally impeded by insufficient light absorption and fast photocarrier recombination. Here, we report a multiple-regulated strategy to capture photons and boost photocarrier dynamics by developing a broadband photocatalyst composed of defect engineered g-C3N4 (DCN) and upconversion NaYF4:Yb3+,Tm3+ (NYF) nanocrystals. Through a precise defect engineering, the S dopants and C vacancies jointly render DCN with defect states to effectively extend the visible light absorption to 590 nm and boost photocarrier separation via a moderate electron-trapping ability, thus facilitating the subsequent re-absorption and utilization of upconverted photons/electrons. Importantly, we found a promoted interfacial charge polarization between DCN and NYF has also been achieved mainly due to Y-N interaction, which further favors the upconverted excited energy transfer from NYF onto DCN as verified both theoretically and experimentally. With a 3D architecture, the NYF@DCN catalyst exhibits a superior solar H2 evolution rate among the reported upconversion-based system, which is 19.3 and 1.5 fold higher than bulk material and DCN, respectively. This work provides an innovative strategy to boost solar utilization by using defect engineering and building up interaction between hetero-materials.

Abstract Y- and Si-based oxide nanopowders were synthesized by a hydrothermal reaction of Y or Si powders with NaOH or LiOH aqueous solution. Nanoparticles with different morphology such as elongated nanospheres, flower-like nanoparticles and nanowires were produced by a control of processing parameters, in particular, the starting composition of solution. The preliminary result of electrochemical examination showed that the hydrothermally processed nanowires exhibit high initial capacities of Li-ion storage: 653 mAh/g for Y2O3 nanowires as anode materials and 186 mAh/g for Li2Si2O5 nanowires as cathode materials in a Li secondary cell. Compared to the powder with elongated sphere or flower-like shapes, the nanowires showed a higher Li-ion capacity and a better cycle property.

Abstract Flower-like nanostructures of Sb2 − x Bi x S3(x = 0.4, 1.0) were successfully prepared using both antimony diethyldithiocarbamate [Sb(DDTC)3] and bismuth diethyldithiocarbamate [Bi(DDTC)3] as precursors under solvothermal conditions at 180 °C. The prepared Sb2 − x Bi x S3 with flower-like 3D architectures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The flower-like architectures, with an average diameter of ~4 μm, were composed of single-crystalline nanorods with orthorhombic structures. The optical absorption properties of the Sb2 − x Bi x S3 nanostructures were investigated by UV–Visible spectroscopy, and the results indicate that the Sb2 − x Bi x S3 compounds are semiconducting with direct band gaps of 1.32 and 1.30 eV for x = 0.4 and 1.0, respectively. On the basis of the experimental results, a possible growth mechanism for the flower-like Sb2 − x Bi x S3 nanostructures is suggested.

Abstract Background RNA-based gene duplicates (retrocopies) played pivotal roles in many physiological processes. Nowadays, functional retrocopies have been systematically identified in several mammals, fruit flies, plants, zebrafish and other chordates, etc. However, studies about this kind of duplication in Caenorhabditis nematodes have not been reported. Findings We identified 43, 48, 43, 9, and 42 retrocopies, of which 6, 15, 18, 3, and 13 formed chimeric genes in C. brenneri, C. briggsae, C. elegans, C. japonica, and C. remanei, respectively. At least 5 chimeric types exist in Caenorhabditis species, of which retrocopy recruiting both N and C terminus is the commonest one. Evidences from different analyses demonstrate many retrocopies and almost all chimeric genes may be functional in these species. About half of retrocopies in each species has coordinates in other species, and we suggest that retrocopies in closely related species may be helpful in identifying retrocopies for one certain species. Conclusions A number of retrocopies and chimeric genes exist in Caenorhabditis genomes, and some of them may be functional. The evolutionary patterns of these genes may correlate with their genomic features, such as the activity of retroelements, the high rate of mutation and deletion rate, and a large proportion of genes subject to trans-splicing.

Abstract Molecular dynamic simulation method has been employed to consider the critical buckling force, pressure, and strain of pristine and defected single-walled carbon nanotube (SWCNT) under axial compression. Effects of length, radius, chirality, Stone–Wales (SW) defect, and single vacancy (SV) defect on buckling behavior of SWCNTs have been studied. Obtained results indicate that axial stability of SWCNT reduces significantly due to topological defects. Critical buckling strain is more susceptible to defects than critical buckling force. Both SW and SV defects decrease the buckling mode of SWCNT. Comparative approach of this study leads to more reliable design of nanostructures.