Search results for "Ray"

Analysis of fluid flow through porous media based on x-ray micro-tomographic reconstructions

2010

This thesis deals with creeping fluid flow through fibrous porous materials. Permeability through a porous medium is a measure of the ability of the material to transmit fluids. For testing and demonstration purposes the permeability values of a few fibrous heterogeneous materials, namely synthetic non-woven felt, wet pressing felt, cardboard, newsprint and hardwood paper, were measured experimentally. Reconstructions of the same materials under similar compression states were captured by x-ray micro-tomography. The actual microscopic pore structure thus obtained was utilised in the numerical lattice-Boltzmann analysis for solving the fluid flow permeability of the materials. Agreement betw…

Structural studies on filamin domain interactions

2015

Salt release monitoring with specific sensors in "in vitro" oral and digestive environments from soft cheeses

2012

International audience; The objective of the present work is to demonstrate the interest and the feasibility of the measurement of NaCl concentrations in soft cheeses and in particular an in vitro digestion process by the use of chemical sensors. The analyzed matrices were the commercial Italian mozzarella cheeses and domestic cheese base models. The classification of mozzarellas was performed according to their salinity, while the breakdown of cheese base models has been followed both at initial steps of digestion in artificial mouth dispositive mimicking the oral sphere and in a gut-imitating digester (TIM-1). During the breakdown of soft cheese in the digester, the estimated values for N…

Broad-band Spectral Evolution of Scorpius X-1 along its Color-Color Diagram

2007

We analyze a large collection of RXTE archive data from April 1997 to August 2003 of the bright X-ray source Scorpius X-1 in order to study the broadband spectral evolution of the source for different values of the inferred mass accretion rate by studying energy spectra from selected regions in the Z-track of its Color-Color Diagram. A two-component model, consisting of a soft thermal component interpreted as thermal emission from an accretion disk and a thermal Comptonization component, is unable to fit the whole 3--200 keV energy spectrum at low accretion rates. Strong residuals in the highest energy band of the spectrum require the addition of a third component that can be fitted with a …

An X-ray characterization of the central region of the supernova remnant G332.5-5.6

2015

Aims. We present an X-ray analysis of the central region of supernova remnant (SNR) G332.5-5.6 through an exhaustive analysis of XMM-Netwon observations with complementary infrared observations. We characterize and discuss the origin of the observed X-ray morphology, which presents a peculiar plane edge over the west side of the central region. Methods. The morphology and spectral properties of the X-ray SNR were studied using a single full frame XMM-Netwon observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE observations at 8, 12 and 24 μm were also used to investigate the properties of the source and its surroundings at different wavelengths. Results. The results show th…

Sub-milliarcsecond imaging of a bright flare and ejection event in the extragalactic jet 3C 111

2020

Context. Flares in radio-loud active galactic nuclei are thought to be associated with the injection of fresh plasma into the compact jet base. Such flares are usually strongest and appear earlier at shorter radio wavelengths. Hence, very long baseline interferometry (VLBI) at millimeter(mm)-wavelengths is the best-suited technique for studying the earliest structural changes of compact jets associated with emission flares. Aims. We study the morphological changes of the parsec-scale jet in the nearby (z = 0.049) γ-ray bright radio galaxy 3C 111 following a flare that developed into a major radio outburst in 2007. Methods. We analyse three successive observations of 3C 111 at 86 GHz with th…

Measurement of activity of the predominant gamma-emitting radionuclides in activated components of a medical cyclotron plan

2008

An identification and activity evaluation of the predominant gamma-emitting radionuclides in activated parts of a medical cyclotron plant by high resolution gamma-ray spectrometry were performed. The use of LaBr3:Ce scintillation and HPGe detectors was examined in order to solve the measurement problems due to high activity of some components used inside a plant provided with an IBA CYCLONE 18/9 cyclotron. For each component, the identification of some key-radionuclides allows to evaluate the surface dose behaviour as function of decay time. The largest activity values are related to radionuclides with half-life of 70-80 days, while radionuclides with higher half-lives represent less than 1…

Structural Changes of Titanium Oxide Induced by Chromium Addition as Determined by an X-Ray Diffraction Study

1995

Abstract An X-ray diffraction study has been carried out on a series of polycrystalline TiO 2 (anatase) catalysts containing Cr(III) at different atomic concentrations (0.2-5.0 at. %), prepared by a co-precipitation method. Analysis of the variation of the unit cell parameters of chromium-doped anatase with respect to pure anatase has allowed us to estimate the solubility limit for the system at around 1.4 at. %. There is no evidence for the existence of a separate crystalline chromium oxide phase. Temperature effects on the cell parameter and on the anatase-rutile transformation rate were also analyzed. An increase in temperature produced release of the chromium from the solid solution. At…

Properties of a triazolopyridine system as a molecular chemosensor for metal ions, anions, and amino acids.

2006

The characteristics as a chemosensor of the compound 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-]pyrimidine (1) have been analyzed. Interaction with Cu(2+) produces a quenching of the fluorescence, while interaction with Zn(2+) leads to a quenching of the fluorescence followed by a bathochromic shift. The crystal structure of the Zn(1)(H(2)O)(3)(ClO(4))(2) x H(2)O complex shows the coordination of Zn(2+) through the terpyridine moiety. The octahedral site is completed by three water molecules. Interactions of the Zn(2+) complex with the anions sulfate, nitrate, nitrite, and dihydrogenphosphate in ethanol produce hypsochromic shifts and restoration of the fluorescence wh…

Dynamic Refolding of Ion-Pair Catalysts in Response to Different Anions.

2019

Four distinct folding patterns were identified in two foldamer-type urea-thiourea catalysts bearing a basic dimethylamino unit by a combination of X-ray crystallography, solution NMR studies, and computational studies (DFT). These patterns are characterized by different intramolecular hydrogen bonding schemes that arise largely from different thiourea conformers. The free base forms of the catalysts are characterized by folds where the intramolecular hydrogen bonds between the urea and the thiourea units remain intact. In contrast, the catalytically relevant salt forms of the catalyst, where the catalyst forms an ion pair with the substrate or substrate analogues, appear in two entirely dif…