89 research outputs found
Deexcitation nuclear gamma-ray line emission from low-energy cosmic rays in the inner Galaxy
Recent observations of high ionization rates of molecular hydrogen in diffuse
interstellar clouds point to a distinct low-energy cosmic-ray component.
Supposing that this component is made of nuclei, two models for the origin of
such particles are explored and low-energy cosmic-ray spectra are calculated
which, added to the standard cosmic ray spectra, produce the observed
ionization rates. The clearest evidence of the presence of such low-energy
nuclei between a few MeV per nucleon and several hundred MeV per nucleon in the
interstellar medium would be a detection of nuclear \gamma-ray line emission in
the range E_ 0.1 - 10 MeV, which is strongly produced in their collisions with
the interstellar gas and dust. Using a recent \gamma-ray cross section
compilation for nuclear collisions, \gamma-ray line emission spectra are
calculated alongside with the high-energy \gamma-ray emission due to {\pi} 0
decay, the latter providing normalization of the absolute fluxes by comparison
with Fermi-LAT observations of the diffuse emission above E \gamma = 0.1 GeV.
Our predicted fluxes of strong nuclear \gamma-ray lines from the inner Galaxy
are well below the detection sensitivies of INTEGRAL, but a detection,
especially of the 4.4-MeV line, seems possible with new-generation \gamma-ray
telescopes based on available technology. We predict also strong \gamma-ray
continuum emission in the 1-8 MeV range, which in a large part of our model
space for low-energy cosmic rays exceeds considerably estimated instrument
sensitivities of future telescopes.Comment: 22 pages, 7 figures, accepted for publication in ApJ; figures 6 and 7
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Multidisciplinary consulting in neuro-orthopedic pathology: An experience in central hospital of Constantine
Gamma ray production cross sections in proton induced reactions on natural Mg, Si and Fe targets over the proton energy range 30 up to 66 MeV
Gamma-ray excitation functions have been measured for 30, 42, 54 and 66 MeV
proton beams accelerated onto C + O (Mylar), Mg, Si, and Fe targets of
astrophysical interest at the separate-sector cyclotron of iThemba LABS in
Somerset West (Cape Town, South Africa). A large solid angle, high energy
resolution detection system of the Eurogam type was used to record Gamma-ray
energy spectra. Derived preliminary results of Gamma-ray line production cross
sections for the Mg, Si and Fe target nuclei are reported and discussed. The
current cross section data for known, intense Gamma-ray lines from these nuclei
consistently extend to higher proton energies previous experimental data
measured up to Ep ~ 25 MeV at the Orsay and Washington tandem accelerators.
Data for new Gamma-ray lines observed for the first time in this work are also
reported.Comment: 11 pages, 6 figures. IOP Institute of Physics Conference Nuclear
Physics in Astrophysics VII, 28th EPF Nuclear Physics Divisional Conference,
May 18-22 2015, York, U
Novel correlations between spectroscopic and morphological properties of activated carbons from waste coffee grounds
Massive quantities of spent coffee grounds (SCGs) are generated by users around the world. Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM,13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data
Optimised protein recovery from mackerel whole fish by using sequential acid/alkaline isoelectric solubilization precipitation (ISP) extraction assisted by ultrasound
peer-reviewedThe growing fishery industry needs to find new green-processes in order to provide a solution to the huge amount of wastes and by-products that such industrial activity produces. Currently, around a 40% of the total weight of the mackerel is considered a by-product, because just the fillets are used in the food market. ISP method has been revealed as a useful tool for protein recovering, however the yield of this process is traditionally lower than enzymatic methods. In present work, the use of sequential acid/alkaline extraction and alkaline extraction assisted by ultrasound, have been implemented in order to increase the yield of the process. It has been demonstrated that (i) sequential extraction is able to recover practically 100% of total protein, and (ii) applying ultrasound to alkaline extraction is possible to recover more than 95% of total protein from mackerel by-products. Extracted proteins were characterized according to their size, and the amino acid profile of final product was determined.This project (Grant-Aid Agreement No. MFFRI/07/01) was carried out under the Sea Change Strategy with the support of the Marine Institute and the Department of Agriculture, Food and the Marine, funded under the National Development Plan 2007–2013
Measurement and analysis of nuclear γ-ray production cross sections in proton interactions with Mg, Si, and Fe nuclei abundant in astrophysical sites over the incident energy range E = 30–66 MeV
The modeling of nuclear
γ
-ray line emission induced by highly accelerated particles in astrophysical sites (e.g., solar flares, the gas and dust in the inner galaxy) and the comparison with observed emissions from these sites needs a comprehensive database of related production cross sections. The most important reactions of protons and
α
particles are those with abundant target elements like C, O, N, Ne, Mg, Si, and Fe at projectile energies extending from the reaction threshold to a few hundred MeV per nucleon. In this work, we have measured
γ
-ray production cross section excitation functions for 30, 42, 54, and 66 MeV proton beams accelerated onto
nat
C
,
C
+
O
(Mylar),
nat
Mg
,
nat
Si
, and
56
Fe
targets of astrophysical interest at the Separated Sector Cyclotron (SSC) of iThemba LABS (near Cape Town, South Africa). The AFRODITE array equipped with eight Compton suppressed high-purity (HPGe) clover detectors was used to record
γ
-ray line energy spectra. For known, intense lines previously reported experimental data measured up to
E
p
≃
25
MeV at the Washington and Orsay tandem accelerators were thus extended to higher proton energies. Our experimental data for the last three targets are reported here and discussed with respect to previous data and to the Murphy et al. compilation [Astrophys. J. Suppl. Ser. 183, 142 (2009)]
Antibacterial Activity and Physical Properties of Edible Chitosan Films Exposed to Low-pressure Plasma
Osmotic evaporation through macroporous hydrophobic membranes: a survey of current research and applications
A review with 18 refs. The principle of osmotic trans-membrane evapn. is exposed and compared to other membrane contactors. The origin and the current description of the vapor flux are critically reviewed as well as the importance of the boundary layers near the membranes. Furthermore, a compilation of results obtained on the lab. and on the industrial scale is given and the disagreements between the conclusions of different research groups are discussed
La consultation pluridisciplinaire en neuro-orthopédie : expérience au CHU de Constantine, Algérie
Erratum: "Deexcitation Nuclear Gamma-Ray Line Emission from Low-energy Cosmic Rays in the Inner Galaxy" (2013, ApJ, 763, 98)
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