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51.
52.
A set of equations is derived which makes possible to study the radiative energy transfer process whereby the photons emitted by the energy donor are absorbed by the energy acceptor and so increase the efficiency of the overall energy transfer. It is shown that the coefficients describing the radiative transfer which appear in the expressions for the intensities of the energy donor and the energy acceptor are not the same, due to the fact that part of the fluorescence absorbed by the acceptor comes from radiation which is not detected as donor emission when there is no acceptor present. The general equations derived are applied to two particular cases commonly considered: measurements in reflection, where the fluorescence emission is observed from the same face of the absorption and measurements in transmission where the fluorescence emission is observed from the opposite face of the cell. 相似文献
53.
54.
The diffusion equation with an added sink term describing the energy transfer by a dipole-dipole mechanism was solved under steady state conditions using the radiation boundary condition. An equation for the non-radiative energy transfer rate constant between organic fluorescent molecules was obtained. This general equation contains the particular cases of a total reflecting boundary condition and the so-called Smoluchowski boundary condition already obtained by other authors. 相似文献
55.
L. Conte C. Fraccaro M. Napoli C. Di Bello G.P. Gambaretto 《Journal of fluorine chemistry》1980,16(6):564
In view of the importance of the medical applications of fluorinated uracil and derivatives, synthetic methods directed to obtain such compounds are of particular interest. Several aspects of the electrochemical fluorination of uracil in different experimental conditions will be discussed. 相似文献
56.
V. Conte L. De Nardo P. Colautti A. Ferretti B. Grosswendt M. Lombardi M. Poggi S. Canella D. Moro G. Tornielli 《Radiation measurements》2010,45(10):1213-1216
The STARTRACK experimental set-up, mounted on the +50° beam line of the Tandem-Alpi particle accelerator of Legnaro National Laboratories, has been conceived to give an experimental basis to nanodosimetric calculations. STARTRACK is based on a detection system able to measure ionization cluster distributions in a 20 nm propane site with a resolution of one ionization. The experimental layout has been designed to minimize pile-up distortions. The background noise is filtered by off-line dedicated software. Electron cluster distribution of 20 MeV protons has been measured. Monte Carlo data and experimental data are pretty well consistent. 相似文献
57.
A mild phase-transfer catalytic reaction has been conducted to O-alkylate the acidic functions of a lignite humic acid (HA), using tetrabutylammonium hydroxide as the phase-transfer catalyst.
The HA acidic functional groups were made to react, in tetrahydrofuran, by nucleophilic substitution with several alkyl halides—methyl
iodide, and ethyl, propyl, and butyl, and benzyl bromide. The occurrence of the O-alkylation reaction was assessed by elemental analysis and 1H NMR, CPMAS 13C NMR, and FTIR spectroscopy. Bonding of alkyl groups increased the carbon and hydrogen content and the H/C ratios of all
the humic reaction products. Increased nitrogen in the reaction products suggested incomplete removal of the phase-transfer
catalyst after purification of the alkylated HA. 1H NMR and CPMAS 13C NMR spectra of alkylated products provided evidence of the successful occurrence of the alkylation reactions. Infrared spectra
confirmed the NMR results, revealing the characteristic absorption of newly formed alkyl and aryl ethers and esters in the
alkylated products and C–H stretching in the aromatic ring of the benzylated derivative. These findings indicate that humic
matter can be successfully alkylated with several different alkylating groups by catalysed phase-transfer reaction. This O-alkylation reaction has the advantage of being mild, versatile, and high-yielding compared with traditional methylation reactions
applied to HA. The possibility of introducing different alkyl groups into the HA by a mild phase-transfer reaction may become
useful by enabling improved fractionation of humic supramolecular associations and further understanding of the molecular
nature of humic substances. 相似文献
58.
Daniela di Serafino Susana Gomez Leopoldo Milano Filippo Riccio Gerardo Toraldo 《Journal of Global Optimization》2010,48(1):41-55
The detection of gravitational waves is a long-awaited event in modern physics and, to achieve this challenging goal, detectors
with high sensitivity are being used or are under development. In order to extract gravitational signals emitted by coalescing
binary systems of compact objects (neutron stars and/or black holes), from noisy data obtained by interferometric detectors,
the matched filter technique is generally used. Its computational kernel is a box-constrained global optimization problem
with many local solutions and a highly nonlinear and expensive objective function, whose derivatives are not available. To
tackle this problem, we designed a real-coded genetic algorithm that exploits characteristic features of the problem itself;
special attention was devoted to the choice of the initial population and of the recombination operator. Computational experiments
showed that our algorithm is able to compute a reasonably accurate solution of the optimization problem, requiring a much
smaller number of function evaluations than the grid search, which is generally used to solve this problem. Furthermore, the
genetic algorithm largely outperforms other global optimization algorithms on significant instances of the problem. 相似文献
59.
Leopoldo Eduardo Cárdenas-Barrón Biswajit Sarkar Gerardo Treviño-Garza 《Applied Mathematical Modelling》2013
Recently, Chiu et al. (2012) [1] present an alternative optimization procedure to derive the optimal replenishment lot size for an economic manufacturing quantity (EMQ) model with rework and multiple shipments. This inventory model was proposed by Chiu et al. (2011) [2]. Both papers do not consider the determining of the number of shipments. This paper determines both the optimal replenishment lot size and the optimal number of shipments jointly. The solution of this paper is better than the solutions of Chiu et al. and . 相似文献
60.
Hui-Ming Wee Wan-Tsu Wang Ming-Chang Lee Leopoldo Eduardo Cárdenas-Barrón 《Applied Mathematical Modelling》2013,37(14-15):7876-7882
This paper presents an alternative approach to solve a finite horizon production lot sizing model with backorders using Cauchy-Bunyakovsky-Schwarz Inequality. The optimal batch size is derived from a sequence number of batches. We prove that a constant batch size policy with one fill rate is better than the variable batch sizes with variable fill rates. Finally, a practical approach is proposed to find the optimal solutions for a discrete planning horizon and discrete batch sizes. 相似文献