نتایج جستجو برای: neutron diffusion
تعداد نتایج: 208482 فیلتر نتایج به سال:
Neutrino opacities important in the evolution of a proto-neutron star containing quark matter are studied. The results for pure quark matter are compared with limiting expressions previously derived, and are generalized to the temperatures, neutrino degeneracies and lepton contents encountered in a proto-neutron star’s evolution. We find that the appearance of quarks in baryonic matter drastica...
The crystal structure of mayenite (ideal composition: Ca12Al14O33) consists of a (disordered) calcium-aluminate framework comprising 32 of the 33 oxygen anions. It contains large open cages, 1/6 of them being filled randomly by the remaining “free” oxygen which is available for diffusion and very high ionic conductivities. This extraframework oxygen could be substituted by nitrogen, opening up ...
Sedimentation of the neutron rich isotope 22Ne may be an important source of gravitational energy during the cooling of white dwarf stars. This depends on the diffusion constant for 22Ne in strongly coupled plasma mixtures. We calculate self-diffusion constants D(i) from molecular dynamics simulations of carbon, oxygen, and neon mixtures. We find that D(i) in a mixture does not differ greatly f...
Abstract. In this paper, we propose a general framework for designing numerical schemes that have both well-balanced (WB) and asymptotic preserving (AP) properties, for various kinds of kinetic models. We are interested in two different parameter regimes, 1) When the ratio between the mean free path and the characteristic macroscopic length ε tends to zero, the density can be described by (adve...
Quasi-elastic neutron scattering was used to monitor the temperature-dependant hydration of tricalcium silicate and Portland cement. Results show that for some samples the degree of hydration is in fact higher at lower curing temperatures. To investigate this effect further, we performed a series of experiments in which samples are initially hydrated at one temperature and then the diffusion pr...
Recently, a new Neutron Radiography (NR) beam line has been designed, constricted, installed and tested based on the use of E-beam tube of Tehran Research Reactor (TRR). Initial tests have been shown that the system can be used for different samples and purposes such as nuclear plates and rods fuels. For this end the system need a suitable irradiation room which should be installed at the NR b...
During the last few years, real time gamma and neutron dosimeters have been developed and semiconductor diodes are frequently used in these dosimeters. Semiconductor diodes are used to charged particle detection. For sensitizing the detector to neutrons, a converter layer is contacted on the front surfaces of them. Incident neutrons interact with the converter and produce charged particles that...
The present review provides an overview of methods and techniques for studying interactions of micro- and nanoparticulate drug delivery system with mucus. Nanocarriers trapped by mucus are featuring a change in particle size and zeta potential that can be utilized to predict their mucus permeation behavior. Furthermore, interactions between nanoparticulate drug delivery systems and mucus layer ...
A gigantic neutron burst of (1-2) × 10 n/s has been detected from deuterated Pd plates with heterostructures set in a vacuum chamber. An explosive release of D2 gas, biaxial bending of all the samples, and excess heat evolution were also observed at the same time. It has been concluded that these phenomena are caused by the cooperative production of D accumulation layers at Pd surfaces due to c...
A combined NMR and neutron diffraction study has been carried out on three Li(3-x-y)Cu(x)N materials with x=0.17, x=0.29 and x=0.36. Neutron diffraction indicates that the samples retain the P6/mmm space group of the parent Li(3)N with Cu located only on Li(1) sites. The lattice parameters vary smoothly with x in a similar fashion to Li(3-x-y)Ni(x)N, but the Li(2) vacancy concentration for the ...
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