One-dimensional nanostructures of SnO 2 with a ribbonlike morphology have been prepared in large scale via rapid oxidation of elemental tin at 1080 °C. The products were characterized with scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, Raman scattering, and photoluminescence spectroscopy. The as-synthesized SnO 2 nanoribbons appeared to be single crystals and had preferred [110] and [203] growth directions. The lengths of the nanoribbons were up to several hundreds of micrometers, and the typical width and thickness were in the range of 30-150 nm and 10-30 nm, respectively. The strong photoluminescence of the nanoribbons in the visible region suggested possible applications in nanoscaled optoelectronic devices. A possible growth mechanism for the SnO 2 nanoribbons was proposed.

ExperimentalOpals shown in this work have been prepared following a method described previously [1,24]. This sol±gel method provides size-controlled spheres for further sedimentation by gravity. The sediments are sintered (thermal annealing at 950 C for 3 h) to control the lattice parameter (a), and to strengthen the structures for consequent infillings. The usual size of the opal bits used for infiltration is 5±9 mm 2 in surface area by 0.5 mm thickness. The sphere diameter is 410 nm and, accordingly, the lattice parameter a = 580 nm.Fixed-Flow Reactor: Sb 2 O 3 -silica composites were placed in the bottom bed of an upflow fixed-bed quartz reactor at atmospheric pressure. The gas flow rate was kept constant at 34 mL min ±1 . The composition of the reactant gas from cylinders controlled by mass flow controllers was 20 vol.-% H 2 S in N 2 .Operating temperature and reaction time were the variables affecting the sulfide growth. Temperatures around 280±300 C are considered optimal for the sulfidation. Samples cracks are apparent as the operating temperature rises up to 550 C (melting point of Sb 2 S 3 ). Sulfidation times of 10 h resulted in almost complete oxide conversion (96 %).Band structure calculations were carried out by using the MIT package software. In this program, the fully vectorial Maxwell equations are solved for plane-wave propagation in a periodic dielectric medium. The system is characterized by the dielectric functions of the voids and backbone, the crystalline structure, and the value of the lattice parameter.Optical Characterization: The measurements were performed with a Fourier transform infrared spectrometer (FTIR), IFS 66S from Bruker with a IRScope II microscope attached. A 36 X Cassegrain objective was used to focus and collect the light. The incident and collected light cover external angles from 15 to 30 from normal incidence with respect to (111) family of planes.The X-ray powder diffraction (XRD) study was carried out in a Siemens 5000 diffractometer using Cu Ka radiation.The reference sample is the commercial product from Aldrich, Antimony trisulfide 99 %+.

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BackgroundThe quality of material medicine resources has had a considerable impact on the development of the health industry, which has created a bottleneck for traditional Chinese medicine (TCM). Dendrobium officinale, which has been widely used for health prevention in TCM, has become a high-nutritive health food that is strongly recommended by many white-collar workers and people who pay more attention to their health. The aim of this study was to develop a method to authenticate and evaluate D. officinale from different origins via simultaneous qualitative and quantitative analyses of flavonoid glycosides. Ultra-high-performance liquid chromatography-electrospray ionization/mass spectrometry was used for the structural elucidation of the compounds.Results9 characteristic peaks, including those representing 7 flavonoid C-glycosides and 2 flavonoid O-glycosides, were identified. Additionally, the contents of 5 representative flavonoid glucosides in 25 batches of D. officinale from different sources were determined. To further investigate the different sources of the 25 batch samples, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were carried out. A study on the methodology revealed that all results were reliable.ConclusionsThis method is an efficient tool for the rapid identification of the different geographical origins of D. officinale and provides references for the quality evaluation of other natural products.