Search results for "RADIATION"
showing 10 items of 5298 documents
Optical properties of TiO2 suspensions: Influence of pH and powder concentration on mean particle size
2007
WOS: 000250584100025
A reaction engineering approach to kinetic analysis of photocatalytic reactions in slurry systems
2016
Abstract The knowledge of the rate equation is fundamental for the assessment of the activity of the photocatalytic material and for the study, design and optimization of photocatalytic reactors. In the case of photocatalytic reactions, the local volumetric rate of photon absorption (LVRPA) affects the reaction rate and its inherently uneven distribution within a “slurry” reactor makes complex a correct kinetic analysis. In the present work it is shown which are the critical aspects of the kinetic analysis in slurry reactors and how to carry out photocatalytic experiments to minimize the misinterpretations of the experimental results. In particular, the influence of the type of illumination…
Quasi-isoactinic reactor for photocatalytic kinetics studies
2007
Photochemical reactors characterized by almost uniform values of the local volumetric rate of photon absorption (LVRPA), i.e., quasi-isoactinic photoreactors, are particularly suitable for assessing the influence of radiant field intensity in kinetic studies. In this work, Monte Carlo simulations have been performed to obtain LVRPA values in a flat photoreactor irradiated on both sides. This configuration appears to be particularly suitable for obtaining quasi-isoactinic conditions. The influence of catalyst albedo and scattering phase function is assessed, and the conditions for obtaining iso-actinicity are discussed. Finally, these conditions are related to an easy-to-measure parameter, n…
Early stages of beta2-microglobulin aggregation and the inhibiting action of alphaB-crystallin
2008
The interest of nucleation of protein crystals and aggregates (including oligomerization) spans from basic physics theory all the way to biophysics, nanophysics, clinical sciences, biotechnologies, food technologies and polymer-solvent interactions. Understanding nucleation within a theoretical framework capable of providing quantitative predictions and control of nucleation rates, or even the very occurrence of crystallization, is a long-sought goal of remarkable relevance to each of the above fields. A large amount of work has been aimed at such goal, but success has been so far rather limited. Work at our laboratory has more recently highlighted a direct link between nucleation rates and…
Water capillary absorption in porous media in different wettability conditions studied by Quantitative MRI and X-ray CT
2007
X-ray computed tomography (CT) and magnetic resonance imaging (MRI) have been successfully applied to study both the capillary properties of several samples of Lecce stone and the performances of treatments used for protection and conservation of historical stone artifacts. The presence of water inside the sample may be visualized by both MRI and X-ray CT. For the treated samples, the different dynamics of water absorption gives indirectly the efficacy of the polymer in the rock.
Recent Achievement and Perspectives in Synchrotron Radiation X-Ray Absorption Spectroscopy
2003
During the last 20 years, x-ray absorption spectroscopy (XAS) has found extensive application in the materials science [1, 2, 3]. solution chemistry [4], biology [5]. therapeutic chemistry [6] and geochemistry. However. it is relatively recently XAS methods have been utilized for measurements on archaeological materials [7,8].
Pressure-induced structural changes in α-MoO3 probed by X-ray absorption spectroscopy
2019
The authors are grateful to Prof. Alain Polian for providing NDAC cell. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. The work was supported by philanthropist MikroTik and administrated by the University of Latvia Foundation.
A new tool for nanoscale X-ray absorption spectroscopy and element-specific SNOM microscopy.
2007
Abstract Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of X-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with scanning near-field optical microscopy (SNOM) detection of the X-ray excited optical luminescence (XEOL) signal. The first results obtained with the prototype instrumentation installed at the European Synchrotron Radiation Facility (Grenoble, France) are presented. They illustrate the possibi…
<title>X-ray absorption spectroscopy study of the local environment around tungsten and molybdenum ions in tungsten-phosphate and molybdenum-ph…
1997
X-ray absorption spectroscopy (XAS) was used to study the local environment around tungsten and molybdenum ions in BaO-P2O5-WO3 and CaO-P2O5-MoO3 glasses having different composition of WO3 and MoO3 oxides. The W L1,3 and Mo K edges x-ray absorption spectra were measured in transmission mode at room temperature using the synchrotron radiation emitted by the ADONE and LURE DCI storage rings, respectively. The analysis of x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) in glasses was performed in comparison with the results for a number of crystalline WO3, CaWO4, Na0.66WO3 alpha- MoO3, beta-MoO3 and amorphous a-WO3, a-MoO3 compounds. The resul…
X-ray absorption spectroscopy of Cu-doped $WO_{3}$ films for use inelectrochemical metallization cell memory
2014
Abstract We have performed the first synchrotron radiation X-ray absorption spectroscopy (EXAFS/XANES) study of the local atomic and electronic structure around Cu and W ions in WO 3 /Cu/WO 3 /Si and WO 3 /Cu/Si multilayered structures, aimed for the application in the electrochemical metallization cell memory. The influence of low-temperature annealing at 135 °C has been investigated in details, and a structural model of Cu-doped WO 3 films is proposed.