Luminescence from TiO2 Nanotubes and Related Nanostructures Investigated Using Synchrotron X-Ray Absorption Near-Edge Structure and X-Ray Excited Optical Luminescence

Understanding the optical property of nanostructured TiO2 is crucial for their use in a variety of applications such as solar cells, photocatalysis, and light emitting devices. Herein, we introduce the use of synchrotron radiation-based spectroscopic techniques: X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) in analyzing the luminescence properties of anodized TiO2 nanotubes (TiO2 NT) and related materials. A description on the spectroscopic technique is first given, including conventional XANES-XEOL combined analysis and a more recently developed 2D XANES-XEOL probing technique. We then discuss several examples of analyzing the luminescence mechanism of TiO2 NT using XANES and XEOL technique, which are the phase transformation accompanied luminescence, luminescence from TiO2 NT hierarchical structure, and metal particle–coated TiO2 NT

Retrieving images from tarnished daguerreotypes using X-ray fluorescence imaging with an X-ray micro beam with tunable energy

We report recent observations using a synchrotron X-ray micro-beam to retrieve images from tarnished 19th century daguerreotypes. We confirm that high quality image can always be retrieved from tarnished plates using Hg Lα XRF as long as the bulk of the image particles and their distribution remains intact. We also report results from using tunable tender X-rays (2 - 7 keV) to conduct imaging in high vacuum at energy above the Ag L-edge and the Hg M-edge, extracting images using Ag Lα and Hg Mα, respectively among others (e.g., S to track corrosion). Images obtained with the surface sensitive total electron yield (TEY) and the bulk sensitive fluorescence yield (FLY) as well as corresponding micro-XANES are reported. Flux tolerance to high intensity X-beam is also explored. These results and their implications for cultural heritage research are discussed

Imaging the Surface of a Hand-Colored 19th Century Daguerreotype.

Daguerreotypes are valued artifacts that constitute a unique historical photographic memory of the 19th century. Understanding their surface chemistry is important in order to conserve and, when necessary, to restore them. Colored highlights were often added by hand to emphasize different features on the daguerreotype\u27s subjects. In the present work, we report on a daguerreotype that was hand-colored with a red pigment that was added to the cheeks of the two individuals. A series of experiments using micro-Raman and micro-Fourier transform infrared spectroscopy and synchrotron-based X-ray fluorescence microscopy and absorption spectroscopy are used to analyze the surface and to determine the nature of the pigment used as well as the common elements present in the fabrication of the daguerreotypes

Publisher Correction: Copper adparticle enabled selective electrosynthesis of n-propanol.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Cr doped ZnO nanostructures: synthesis, electronic structures and magnetic properties

We report an experiment in which we have attempted to dope Cr into ZnO nanostructure as a function of dopant concentration using sol-gel method, followed by controlled thermal annealing with some success. We have also examined the samples thus prepared with scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Near Edge X-ray Absorption Fine Structure (NEXAFS), both theory and experiments, and magnetic measurements. We found that low concentration of Cr can indeed be doped in ZnO and is substitutional, occupying the tetrahedral site. However, upon increasing dopant concentration and annealing temperature, a secondary phase with Cr occupying an octahedral site precipitates out as evident from SEM, XRD and NEXAFS. Ferromagnetism at room temperature was not observed in any samples although at low Cr concentration and 400 째C processing temperature antiferromagnetism can be seen but at higher concentrations or processing temperatures the samples show only paramagnetism.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Large-scale Hollow Nanoparticles Identification by X-ray Absorption Spectroscopy

Large-scale SiO2 hollow nanoparticles were synthesized by a sol-gel method. The composition, morphology and chemical bonding information of SiO2 hollow nanoparticles were studied by X-ray absorption near edge structure (XANES) and scanning transmission X-ray microscopy (STXM). XANES at the Si L-edge and K-edge reveal the characteristics of hollow nanoparticles, which are essentially amorphous SiO2 with a slightly longer Si-O bond than SiO2 nanoparticles on average and deficiencies in oxygen. Individual SiO2 hollow spheres were also examined using STXM, which provides spectro-microscopic information as well as the absolute thickness of the sample.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author