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241.
Rodríguez FJ Sánchez C Villacampa B Alcalá R Cases R Millaruelo M Oriol L 《The Journal of chemical physics》2005,123(20):204706
Pulsed light-induced recording in azobenzene polymers has recently been studied due to its potential use in optical storage applications. In this paper we study the photoinduced birefringence (Deltan) and holographic grating recording in an azobenzene side chain liquid-crystalline polymethacrylate irradiating with a single 4 ns light pulse at 532 nm. For some irradiation conditions, Deltan grows in less than 50 ns reaching an essentially stable value of about 10(-2). Holographic gratings have been registered using intensity and polarization patterns. Fast response and stability, similar to those of Deltan, was observed in the holographic recording process. Both light-induced anisotropy and relief contributions have been found in the case of gratings recorded using intensity patterns, relief being the dominant contribution at high recording energies. Polarization gratings have been recorded using two orthogonally circularly polarized beams. The resultant gratings showed stable efficiencies up to 0.8% (measured at 633 nm in 1-mum-thick films) and no measurable relief was observed. 相似文献
242.
Kubinec R Adamuscin J Jurdáková H Foltin M Ostrovský I Kraus A Soják L 《Journal of chromatography. A》2005,1084(1-2):90-94
A simple method of solventless extraction of volatile organic compounds (benzene, toluene, ethylbenzene and xylenes) from aqueous samples was developed. This method allows direct injection of large volume of water sample into a gas chromatograph using the sorption capacity of the sorbent Chromosorb P NAW applied directly in the injection port of gas chromatograph. The system prevent water penetration into a column, keep it adsorbed on its surface until the analytes are stripped into a column, and the residual water is purging using split flow. The limit of detection ranging from 0.6 for benzene to 1.1 microg l(-1) for o-xylene and limit of quantification ranging 2.0-3.6 microg l(-1) are lower that those reached by gas chromatography with flame ionization detection and direct aqueous injection before. 相似文献
243.
Shellie RA Welthagen W Zrostliková J Spranger J Ristow M Fiehn O Zimmermann R 《Journal of chromatography. A》2005,1086(1-2):83-90
The potential for the utilization of GC x GC-time-of-flight (TOF) MS for high-resolution metabolomics studies is discussed, with the implementation of some statistical comparisons for biomarker detection. Metabolite profiles from NZO obese mice versus BL/6 control mice are compared and contrasted using a number of chromatogram comparison routines, including direct chromatogram comparisons, chromatogram subtraction and averaging routines, as well as a method for generating relative weighted peak surface difference chromatograms, and a more conventional Student's t-test statistical approach. 相似文献
244.
It is shown that hydrogen peroxide enhances substantially selective reduction of NOx to nitrogen with hydrocarbons over Ag/alumina catalysts. 相似文献
245.
246.
247.
A. P. C. Malbouisson F. R. A. Simão J. Sá Borges 《Zeitschrift fur Physik C Particles and Fields》1985,29(1):75-77
We give a naïve perturbative proof of the existence of infrared renormalons for large distance asymptotically free theories. We argue that the extension of the result for small distance asymptotically free theories is not obvious. Indeed we do not find infrared renormalons for QCD. 相似文献
248.
Z. Chvoj Z. Chromcová V. Cháb 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(3):453-461
In this article we investigate the complex 1D mesoscopic model of adatom diffusion and the evolution of an ordered phase on
the substrate surface. The analysis of the theoretical model is compared with the experimental results of the spreading of
Au
adatoms on Si(111)-(7×7) surface. The steady state solutions and their stability conditions are determined within the concept
of the traveling-wave solution. It is shown that the formation of the ordered
phase (5×2) and the difference in the diffusion of Au on (7×7) and on (5×2) structure results in a sharp edge of diffusion
front which corresponds to the coverage of a saturated
(5×2) phase. This edge moves linearly in time and α can be determined by experiment. The system of model equations enables
the damped waves solution or temporary evolution of two steps. 相似文献
249.
We develop a theoretical approach to percolation in random clustered networks. We find that, although clustering in scale-free networks can strongly affect some percolation properties, such as the size and the resilience of the giant connected component, it cannot restore a finite percolation threshold. In turn, this implies the absence of an epidemic threshold in this class of networks, thus extending this result to a wide variety of real scale-free networks which shows a high level of transitivity. Our findings are in good agreement with numerical simulations. 相似文献
250.
Hendry E Koeberg M Wang F Zhang H de Mello Donegá C Vanmaekelbergh D Bonn M 《Physical review letters》2006,96(5):057408
We independently determine the subpicosecond cooling rates for holes and electrons in CdSe quantum dots. Time-resolved luminescence and terahertz spectroscopy reveal that the rate of hole cooling, following photoexcitation of the quantum dots, depends critically on the electron excess energy. This constitutes the first direct, quantitative measurement of electron-to-hole energy transfer, the hypothesis behind the Auger cooling mechanism proposed in quantum dots, which is found to occur on a 1 +/- 0.15 ps time scale. 相似文献