Search results for " composition"
showing 10 items of 1437 documents
Production of hypernuclei in peripheral relativistic ion collisions
2013
Within a dynamical and statistical approach we study the main regularities in production of hypernuclei coming from projectile and target residues in relativistic ion collisions. We demonstrate that yields of hypernuclei increase considerably above the energy threshold for Lambda hyperons, and there is a saturation for yields of single hypernuclei with increasing the beam energy up to few TeV. Production of specific hypernuclei depend very much on the isotopic composition of the projectile, and this gives a chance to obtain exotic hypernuclei that may be difficult to reach in traditional hypernuclear experiments. Possibilities for the detection of such hypernuclei with planned and available…
The performance of thin layers produced by molecular plating as α-particle sources
2013
Abstract Sources for α-spectroscopy studies were prepared. Constant current density molecular plating was used to produce layers containing the α-particle emitter 147 Sm. Different parameters of the molecular plating process were varied, namely the plating solvent (an isopropanol/isobutanol mixture, pyridine, and N , N -dimethylformamide), the applied deposition time (90, 180, and 360 min), and the surface roughness of the deposition substrate (ca. 10, 20, and 300 nm). Using different analytical techniques, Sm deposition yields, chemical composition of the produced surfaces, surface homogeneity, roughness and morphology were investigated. Alpha spectra were recorded with a Si solid-state de…
Modelling of Magnetic Resonance Spectra Using Mixtures for Binned and Truncated Data
2007
Magnetic Resonance Spectroscopy (MRS) provides the biochemical composition of a tissue under study. This information is useful for the in-vivo diagnosis of brain tumours. Prior knowledge of the relative position of the organic compound contributions in the MRS suggests the development of a probabilistic mixture model and its EM-based Maximum Likelihood Estimation for binned and truncated data. Experiments for characterizing and classifying Short Time Echo (STE) spectra from brain tumours are reported.
A detailed spectroscopy of the carbon-rich star BD +57° 2161
2005
An LTE abundance analysis based on high-resolution spectra is presented for the carbon-rich star BD +57° 2161, whose evolutionary status is unknown. With [C/Fe] = +0.4 dex and a mean s-process overabundance of [s/Fe] ≃ +1.5 dex the peculiar atmospheric composition of BD +57° 2161 is confirmed. The 12 C/ 13 C abundance ratio was found to be about 10. The mild iron deficiency, [Fe/H] = -0.2, supports the idea that BD +57° 2161 could be an old-disk-population object. Radial-velocity measurements confirm the binary nature of the star. Therefore the peculiar chemical composition could be due to the mass transfer from the secondary - AGB star in the past. Orbital parameters are estimated for anot…
The 2014 KIDA network for interstellar chemistry
2015
Chemical models used to study the chemical composition of the gas and the ices in the interstellar medium are based on a network of chemical reactions and associated rate coefficients. These reactions and rate coefficients are partially compiled from data in the literature, when available. We present in this paper kida.uva.2014, a new updated version of the kida.uva public gas-phase network first released in 2012. In addition to a description of the many specific updates, we illustrate changes in the predicted abundances of molecules for cold dense cloud conditions as compared with the results of the previous version of our network, kida.uva.2011.
SU-E-T-508: Monte Carlo Dosimetric Study of the CSM40 Low Dose Rate Source
2013
Purpose: There is a LDR 137Cs brachytherapy source, CSM40, developed by Eckert & Ziegler BEBIG. Fundamental dosimetric datasets to be used on treatment planning systems do not exist for this source. This study aims to obtain quality dosimetric data for this source for its use in clinical practice as required by AAPM and ESTRO. Methods: Penelope2008 and GEANT4 Monte Carlo codes were used to characterize this source dosimetry. Water composition and mass density was that recommended by AAPM. Due to the typical energies of the 137 Cs, dose for small distances can be approximated by collisional kerma. Therefore, we have considered collisional kerma for r<20 cm. To provide adequate spatial resolu…
Biosilicification of loricate choanoflagellate: organic composition of the nanotubular siliceous costal strips of Stephanoeca diplocostata.
2010
SUMMARY Loricate choanoflagellates (unicellular, eukaryotic flagellates; phylum Choanozoa) synthesize a basket-like siliceous lorica reinforced by costal strips (diameter of approximately 100 nm and length of 3 μm). In the present study, the composition of these siliceous costal strips is described, using Stephanoeca diplocostata as a model. Analyses by energy-dispersive X-ray spectroscopy (EDX), coupled with transmission electron microscopy (TEM), indicate that the costal strips comprise inorganic and organic components. The organic, proteinaceous scaffold contained one major polypeptide of mass 14 kDa that reacted with wheat germ agglutinin. Polyclonal antibodies were raised that allowed …
Litchi (Litchi chinensis Sonn.): a comprehensive review of phytochemistry, medicinal properties, and product development
2021
Since ancient times, litchi has been well recognized as a functional food for the management of various ailments. Many bioactives, including flavanoids, anthocyanins, phenolics, sesquiterpenes, triterpenes, and lignans, have been identified from litchi with a myriad of biological properties both in vitro and in vivo. In spite of the extensive research progress, systemic reviews regarding the bioactives of litchi are rather scarce. Therefore, it is crucial to comprehensively analyze the pharmacological activities and the structure-activity relationships of the abundant bioactives of litchi. Besides, more and more studies have focused on litchi preservation and development of its by-products,…
A Unique Collection of Palaeolithic Painted Portable Art: Characterization of Red and Yellow Pigments from the Parpalló Cave (Spain).
2016
In this work we analyze the pigments used in the decoration of red and yellow motifs present in the portable art of the Parpallo Cave (Gandia, Spain), one of the most important Palaeolithic sites in the Spanish Mediterranean region. Energy dispersive X-ray fluorescence spectrometry (EDXRF) and spectrophotometry in the visible region (CIEL*a*b*color coordinates and spectral reflectance curves) were used to perform in situ fast analyses of the red and yellow motifs with portable equipment and to characterize their elemental composition and their colorimetric perception, respectively. According to the elemental composition, the intensity of the fluorescence iron signals in red and yellow motif…
EDXRF analysis of the Pentecost Triptych from the “São Pedro de Miragaia” church (Porto, Portugal)
2013
Abstract EDXRF spectrometry was used to determine the pigment composition of the Pentecost Triptych, a Flemish masterpiece located at the Church of Sao Pedro de Miragaia (Porto, Portugal). The triptych was restored at the beginning of the 20th century and presents a great number of zones with repaints and colour alterations that can be observed on the whole of their surface. The identification of the original pigments and restoration pigments was based on their characteristic colour and the correlation between the detected elements and the named “key elements” of ancient pigments (Ca, Fe, Cu, Hg, Pb,…) and modern pigments (Ti, Ba, Cr, Zn, Co, Cd,…). The analysis of the triptych has been car…