Template-Free Electrodeposition of One-Dimensional Nanostructures of Tellurium

Without the aid of surfactants or catalysts, one-dimensional (1D) nanostructures of Te (nanowires with a small quantity of nanotubes and nanoribbons) have been synthesized directly from template-free electrodeposition (TFED) in an aqueous solution at low temperature. As observed by electron microscopy, the as-grown Te nanomaterials are single crystalline trigonal structure and contain few defects. The preferential growth of these 1D nanostructures along the [001] direction is attributed to the intrinsic anisotropic crystal structure of Te and the special growth condition of TFED. It is anticipated that TFED could be used as a versatile approach to synthesize various I D materials which contain intrinsic highly anisotropic crystal strictures

Identification and Antifungal Activity of Compounds from the Mangrove Endophytic Fungus Aspergillus clavatus R7

Two new coumarin derivatives, 4,4′-dimethoxy-5,5′-dimethyl-7,7′-oxydicoumarin (1), 7-(γ,γ-dimethylallyloxy)-5-methoxy-4-methylcoumarin (2), a new chromone derivative, (S)-5-hydroxy-2,6-dimethyl-4H-furo[3,4-g]benzopyran-4,8(6H)-dione (5), and a new sterone derivative, 24-hydroxylergosta-4,6,8(14),22-tetraen-3-one (6), along with two known bicoumarins, kotanin (3) and orlandin (4), were isolated from an endophytic fungus Aspergillus clavatus (collection No. R7), isolated from the root of Myoporum bontioides collected from Leizhou Peninsula, China. Their structures were elucidated using 1D- and 2D- NMR spectroscopy, and HRESIMS. The absolute configuration of compound 5 was determined by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Compound 6 significantly inhibited the plant pathogenic fungi Fusarium oxysporum, Colletotrichum musae and Penicillium italicum, compound 5 significantly inhibited Colletotrichum musae, and compounds 1, 3 and 4 greatly inhibited Fusarium oxysporum, showing the antifungal activities higher than those of the positive control, triadimefon

Template-free electrochemical synthesis of single-crystal CuTe nanoribbons

Copper telluride (CuTe) is a transition metal chalcogenide with interesting electronic and photoelectric properties and potential applications. In this study, CuTe nanoribbons were successfully synthesized for the first time by an electrochemical method from an aqueous solution at 85 degrees C without using any template or capping agent. The composition of the nanoribbons was determined by the energy-dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The morphology and crystal structure of the as-grown CuTe nanoribbons were characterized by scanning electron microscopy (SEM), electron diffraction (ED), and high-resolution transparent electron inicroscopy (HRTEM). The CuTe nanoribbons have single-crystal orthorhombic structure and grown along the [010] direction. The growth mechanism of the nanoribbons is discussed based on the experimental conditions and the special layer structure of CuTe

Dynamic large-array terahertz imaging display based on high-performance 1D/2D tellurium homojunction modulators

Mixed-dimensional van der Waals systems could improve terahertz modulators’ performance by utilizing the advantages of different dimensional materials. However, the reported available mixed-dimensional heterojunctions using two-dimensional (2D) and three-dimensional materials usually sacrifice the modulation speed to realize a higher modulation depth. Here, we creatively integrate one-dimensional (1D) nanowires with 2D nanofilms to construct the novel mixed-dimensional tellurium (Te) homojunction and achieve optimal indices with an ultrahigh modulation depth and a shorter carrier lifetime. In addition, a Te-based large-array imaging element was fabricated to successfully reproduce the painting colors under specific pump conditions as well as the dynamic multicolor display. Further measurements with the introduction of metamaterials prove that the required energy consumption can be significantly reduced by one order of magnitude. Our proposed 1D/2D integration strategy opens a new way to build high-performance terahertz functional devices and greatly expands the application fields of Te nanomaterials

18O isotopic study of photo-induced formation of peroxide species on cubic Nd2O3

Photo-induced formation of peroxide species on cubic Nd2O 3 was studied by in situ microprobe Raman spectroscopy using 18O as a tracer and a 325-nm laser as an excitation source. The results confirmed that the peroxide ions were formed through photooxidation of the lattice oxygen species in neodymium sesquioxide by molecular oxygen species. Under UV excitation (λ = 325 nm), the reaction between O2 and O2- could take place at room temperature. A fast oxygen exchange between the peroxide ions and the lattice oxygen species in Nd2O 3 took place under the experimental conditions studied. Also, bulk lattice oxygen species in Nd2O3 could migrate to the surface layer and participate in the formation of peroxide ions. The migration of lattice oxygen species and the oxygen exchange between lattice oxygen and peroxide ions were promoted by UV laser irradiation. ? 2014 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences

Facile Method for Modification of the Silicon Nanowires and Its Application in Fabrication of pH-Sensitive Chips

A novel, facile, and effective method for modification of SiNWs or SiNW arrays has been developed. In this method, reaction between reductive Si–H bonds on the surface of SiNWs and the aldehyde group containing in organic molecules has been used for immobilization of organic molecules onto the surface of SiNW arrays. The method is time saving and can be operated at room temperature without any other complex reaction requirement. Fluorescence images, XPS, fluorescence spectra, and IR spectra were used for characterization of the modification. Through this method, a SiNW array-based pH sensitive chip was realized by covalently immobilizing 5-aminofluorescein molecules onto the surface of SiNW arrays with glutaraldehyde as linker molecules. Fluorescence intensity of the chip increased with increasing of pH value and a linear relationship between fluorescence intensity and pH values was acquired. In addition, the chip has been successfully used for real-time and in situ monitoring of extracellular pH changes for live HeLa cells and the result exhibited fine resolution of time and space