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971.
972.
Claudio Luchinat 《Angewandte Chemie (International ed. in English)》2012,51(42):10445-10445
973.
974.
Rita Traversi Silvia Becagli Emiliano Castellano Ombretta Largiuni Alessio Migliori Mirko Severi 《International journal of environmental analytical chemistry》2013,93(6-7):457-470
The chemical analysis of shallow firn cores sampled in coastal and plateau areas in Northern Victoria Land and along a transect from Talos Dome to Dome C (East Antarctica, Pacific Ocean sector) allowed a global view of spatial and temporal changes in chemical composition of snow depositions over the last 100 years. Variations in concentration of primary (sea spray) and secondary (biogenic emission, atmospheric inputs) source markers were observed and discussed as a function of distance from the sea and altitude. In the stations characterized by relatively high snow accumulation rates, the sub-sampling resolution was sufficient to obtain a stratigraphic dating by using the periodical variations of seasonal markers. In these stations, a subdivision in “summer” and “winter” samples was carried out in order to study the seasonal changes of the contributions of the measured compounds to the snow composition as elevation and distance from the sea increase. Some evidence of post-depositional effects which are able to change the original deposition of chloride and nitrate, was observed at stations with low accumulation rates. The reliability of the depth/concentration profile of these substances for reconstructing past deposition was also discussed. 相似文献
975.
Pavel Bedrikovetsky Fernando D. Siqueira Claudio A. Furtado Antonio Luiz S. Souza 《Transport in Porous Media》2011,86(2):353-383
Particle detachment from the rock during suspension transport in porous media was widely observed in laboratory corefloods
and for flows in natural reservoirs. A new mathematical model for detachment of particles is based on mechanical equilibrium
of a particle positioned on the internal cake or matrix surface in the pore space. The torque balance of drag, electrostatic,
lifting and gravity forces, acting on the particle from the matrix and the moving fluid, is considered. The torque balance
determines maximum retention concentration during the particle capture. The particle torque equilibrium is determined by the
dimensionless ratio between the drag and normal forces acting on the particle. The maximum retention function of the dimensionless
ratio (dislodging number) closes system of governing equations for colloid transport with particle release. One-dimensional
problem of coreflooding by suspension accounting for limited particle retention, controlled by the torque sum, allows for
exact solution under the assumptions of constant filtration coefficient and porosity. The explicit formulae permit the calculation
of the model parameters (maximum retention concentration, filtration and formation damage coefficients) from the history of
the pressure drop across the core during suspension injection. The values for maximum retention concentration, as obtained
from two coreflood tests, have been matched with those calculated by the torque balance on the micro scale. 相似文献
976.
977.
Mahdi Sadeghi Omid Kiavar S. Hamed Hosseini Rozhin Fatehi Claudio Tenreiro 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):565-571
The Nitinol stent was bombarded in a cyclotron at a flux rate of 4 μA/cm2 to produce 48V via 48Ti (p, n) 48V reaction. In this study dose distribution of 48V radioactive stent was investigated for renal arteries. Version X-2.6 of the MCNP Monte Carlo radiation transport system
code was employed to calculate dose distribution around the stent. As 48V is a mixed gamma and beta particle emitter, two separate runs of MCNP for both beta and gamma particles were performed and
the total deposited dose was acquired by adding the two mentioned values. In order to verify the simulation, the calculated
results have been compared with previous published data for the source. Calculated results show high dose gradient near the
stent and the maximum amount of dose deposits at the vessel wall. According to (AAPM) TG-60/149 protocol, the dosimetric parameters,
including geometry function, G(ρ,z), radial dose function, g
L
(ρ), and anisotropy function, F(ρ,z), were also determined. 相似文献
978.
979.
980.
19F NMR transverse and longitudinal relaxation filter experiments for screening: a theoretical and experimental analysis
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Ligand‐based 19F NMR screening represents an efficient approach for performing binding assays. The high sensitivity of the methodology to receptor binding allows the detection of weak affinity ligands. The observable NMR parameters that are typically used are the 19F transverse relaxation rate and isotropic chemical shift. However, there are few cases where the 19F longitudinal relaxation rate should also be used. A theoretical and experimental analysis of the 19F NMR transverse and longitudinal relaxation rates at different magnetic fields is presented along with proposed methods for improving the sensitivity and dynamic range of these experiments applied to fragment‐based screening. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献