Search results for "X-Ray"

Herbig-Haro objects: model prediction and comparison with X-ray and optical observations

2007

X-ray emission from fast moving shocks in the protostellar jet HH 154: a binding diagnostic of the emission mechanism

2004

We propose to determine the proper motion of the X-ray source associated with HH 154, the only known protostellar jet in which the X-ray emission mechanism can be studied in detail. Our numerical simulations indicate that the X-rays are produced in a fast-moving (500 km/s) post-shock region, and our HST observations show high proper motion shocked material moving at similar speed. Detection (or lack of) of proper motion of the X-ray source will strongly confirm (or falsify) our model, and constitute the basis for a general theory of X-ray emission in protostellar jets. Understanding and modeling the emission mechanism is key to assess the lifetime of the X-ray emission and thus the influenc…

Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria

2018

A simple and straightforward synthetic approach for carbon nanodots (C-dots) is proposed. The strategy is based on a one-step hydrothermal chemical reduction with thiourea and urea, leading to high quantum yield C-dots. The obtained C-dots are well-dispersed with a uniform size and a graphite-like structure. A synergistic reduction mechanism was investigated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The findings show that using both thiourea and urea during the one-pot synthesis enhances the luminescence of the generated C-dots. Moreover, the prepared C-dots have a high distribution of functional groups on their surface. In this work, C-dots proved …

Efficient Consecutive Synthesis of Ethyl-2-(4-Aminophenoxy) Acetate, a Precursor for Dual GK and PPARγ Activators, X-ray Structure, Hirshfeld Analysi…

2022

Herein, we report a facile synthesis of ethyl-2-(4-aminophenoxy)acetate 4 as a building synthon for novel dual hypoglycemic agents. This building template was synthesized by alkylation of 4-nitrophenol with ethyl bromo-acetate followed by selective reduction of the nitro group. This reduction methoddoes not require nascent hydrogen or any reaction complexity; it goes easily via consecutive reaction in NH4Cl/Fe to yield our target synthon as very pure crystals. This product was characterized by 1HNMR, 13CNMR, COSY, NOESY NMR spectroscopy, and elemental analysis. Additionally, its structure was studied and approved by X-ray single crystal structure determination. The unit cell parameters are …

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

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…

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…