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排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
The partition coefficient of strontium upon its extraction from the aqueous solutions of picric acid into chloroform containing DC-18-crown-6, B-15-crown-5 after their exposition to gamma radiation has been studied. A significant decrease of the partition coefficient in the studied range of doses 10–70 kGy was observed. This effect can be attributed to the radiolytic products of chloroform. The radiation destruction as well as dehydrogenation of crown ethers were not observed. 相似文献
2.
Rafael Bilbao María Benita Murillo Angela Millera Jos Francisco Mastral 《Thermochimica Acta》1991,190(2):163-173
An experimental system that allows the use of large particle sizes and the simulation of different operating conditions was built to study the thermal decomposition of lignocellulosic materials. The values of solid conversion and of temperature obtained at different points using spherical particles of pine wood 2 cm in diameter are shown. The conversion values are compared with those calculated from the equations obtained in a thermobalance for small particle sizes. 相似文献
3.
Izaskun Bustero García Ainara Obieta Isabel Muñoz Roberto Rincón Inés Arteche Amaya 《Mikrochimica acta》2006,152(3-4):239-247
Interest in carbon nanotubes (CNT) has grown at a very rapid rate in the last decade. Their interesting physical and chemical
properties open attractive possibilities in many application areas. These properties depend on the process conditions during
synthesis and on subsequent purification steps. Recent studies have demonstrated that CNT can promote the electron transfer
of biomolecules. These exceptional properties make them attractive for use in electrochemical biosensors.
Multi walled nanotubes have been synthesized by the Chemical Vapor Deposition (CVD) method using methane as a carbon source
and Ni–Al2O3–SiO2 as the catalyst. The influence of the variation of certain reaction parameters such as feed gas composition, catalyst mass,
temperature and reaction time in the yield of the CVD process has been established. In addition, the structural and chemical
characteristics of the CNTs have been studied and a purification process to eliminate the catalyst and amorphous carbon has
been developed that involves a gaseous oxidative process and acid treatment. The efficiency of the purification step has been
determined by analytical techniques.
Atomic force microscopy, Raman scattering, thermogravimetric analysis, inductively coupled plasma atomic spectroscopy are
the characterization techniques employed in this work. 相似文献
4.
An experimental study of the thermal decomposition of powdered cellulose and pine sawdust has been performed. The influence of the heating rate on the temperature profiles in the sample and on the solid conversion rate has been studied. A mathematical model without adjustable parameters has been used to calculate the temperature at different points in the solid bed and the average total solid conversion. The experimental results have been compared with those calculated by the model. A good agreement has been obtained for sawdust. Some differences are observed for cellulose at high heating rates, and the influence of the thermal conductivity and the reaction heat on the results has been analysed. 相似文献
5.
Stefan Bilbao Olivier Thomas Cyril Touzé Michele Ducceschi 《Numerical Methods for Partial Differential Equations》2015,31(6):1948-1970
This article is concerned with the numerical solution of the full dynamical von Kármán plate equations for geometrically nonlinear (large‐amplitude) vibration in the simple case of a rectangular plate under periodic boundary conditions. This system is composed of three equations describing the time evolution of the transverse displacement field, as well as the two longitudinal displacements. Particular emphasis is put on developing a family of numerical schemes which, when losses are absent, are exactly energy conserving. The methodology thus extends previous work on the simple von Kármán system, for which longitudinal inertia effects are neglected, resulting in a set of two equations for the transverse displacement and an Airy stress function. Both the semidiscrete (in time) and fully discrete schemes are developed. From the numerical energy conservation property, it is possible to arrive at sufficient conditions for numerical stability, under strongly nonlinear conditions. Simulation results are presented, illustrating various features of plate vibration at high amplitudes, as well as the numerical energy conservation property, using both simple finite difference as well as Fourier spectral discretizations. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 1948–1970, 2015 相似文献
6.
Phosphatidylcholine‐Coated Iron Oxide Nanomicelles for In Vivo Prolonged Circulation Time with an Antibiofouling Protein Corona 下载免费PDF全文
Hugo Groult Dr. Jesús Ruiz‐Cabello Ana Victoria Lechuga‐Vieco Dr. Jesús Mateo Dr. Marina Benito Izaskun Bilbao Dr. María Paz Martínez‐Alcázar Dr. Juan. Antonio Lopez Dr. Jesús Vázquez Dr. Fernando F. Herranz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16662-16671
We report the synthesis of micellar phosphatidylcholine‐coated superparamagnetic iron oxide nanoparticles as a new long circulation contrast agents for magnetic resonance imaging. Oleic acid‐coated Fe3O4 nanoparticles were first prepared through thermal degradation and then encapsulated into small clusters with a phosphatidylcholine coating to obtain hydrophilic nanomicelles. A thorough characterization confirmed the chemical nature of the coating and the excellent colloidal stability of these nanomicelles in aqueous media. Magnetization and relaxivity properties proved their suitability as magnetic resonance imaging (MRI) contrast agent and in vitro cell viability data showed low toxicity. Vascular lifetime and elimination kinetics in the liver were assessed by blood relaxometry and by in vivo MRI in rats and compared with “control” particles prepared with a polyethylene glycol derivative. These micellar particles had a lifetime in blood of more than 10 h, much longer than the control nanoparticles (≈2 h), which is remarkable considering that the coating molecule is a small biocompatible zwitterionic phospholipid. The protein corona was characterized after incubation with rat serum at different times by high‐throughput proteomics, showing a higher proportion of bound apolipoproteins and other dysopsonins for the phosphatidylcholine particles. The antibiofouling properties of this corona and its resistance to the adsorption of proteins corroborate the observed enhanced stability and prolonged systemic circulation. 相似文献
7.
Juliá n Aguirre Mikel Bilbao Juan Carlos Peral. 《Mathematics of Computation》2006,75(253):385-393
For all totally positive algebraic numbers except a finite number of explicit exceptions, the following inequality holds:
where is the degree of and its conjugates. This improves previous results of Smyth, Flammang and Rhin.
\max(1.780022,1.66+\alpha_1), \end{displaymath}">
where is the degree of and its conjugates. This improves previous results of Smyth, Flammang and Rhin.
8.
Stefan Bilbao 《Numerical Methods for Partial Differential Equations》2004,20(3):463-480
This article is devoted to an analysis of simple families of finite difference schemes for the wave equation. These families are dependent on several free parameters, and methods for obtaining stability bounds as a function of these parameters are discussed in detail. Access to explicit stability bounds such as those derived here may, it is hoped, lead to optimization techniques for so‐called spectral‐like methods, which are difference schemes dependent on many free parameters (and for which maximizing the order of accuracy may not be the defining criterion). Though the focus is on schemes for the wave equation in one dimension, the analysis techniques are extended to two dimensions; implicit schemes such as ADI methods are examined in detail. Numerical results are presented. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 463–480, 2004. 相似文献
9.
Jos M. Arandes Javier Erea Miren J. Azkoiti Martin Olazar Javier Bilbao 《Journal of Analytical and Applied Pyrolysis》2003,70(2):975-760
A study has been made of the cracking on a mesoporous silica of polystyrene (PS) and polystyrene-butadiene (PS-BD) dissolved in a light cycle oil (LCO) from a product stream of a commercial fluid catalytic cracking (FCC) unit. This study has been carried out in a reactor of short contact time (3 s) in the 723–823 K range. This strategy for simultaneous valorization of plastics and solvent avoids the technological problems inherent to the treatment of solid postconsumer-plastics and the limitation to heat transfer in the process of pyrolysis. The cracking of plastics has a synergistic effect on the conversion of LCO, as it contributes to increasing the yield of gasoline (C5–C12). The cracking of the PS/LCO blend produces high yields of styrene, whereas the cracking of the PS-BD/LCO blend produces a stream of products with petrochemical interest. 相似文献
10.
In the classical model of games with transferable utility one assumes that each subgroup of players can form and cooperate
to obtain its value. However, we can think that in some situations this assumption is not realistic, that is, not all coalitions
are feasible. This suggests that it is necessary to raise the whole question of generalizing the concept of transferable utility
game, and therefore to introduce new solution concepts. In this paper we define games on matroids and extend theτ-value as a compromise value for these games.
This work has been partially supported by the Spanish Ministery of Science and Technology under grant SEC2000-1243. 相似文献