We present how the luminescence of europium RR-2-P-oxides complexes can be increased by interaction of electronic levels of the complex with the radiation field of silver nanoparticles (NPs). The procedure by which silver NPs are formed in a sol-gel polyurethane matrix precursor was elaborated. The formed Ag NPs were combined with Eu complex incorporated in ormocer matrix. The emission spectra of the complexes without silver NPs were compared with spectra of the same complexes with addition of silver NPs. As the result of the interaction of the electronic levels of lanthanide ligands with silver plasmons, dramatic increase of luminescence was observed. 相似文献
Structural and magnetic properties of amorphous and crystalline alloys Fe73.5Cu1Nb3B9Si13?xGex=1;5;10;13.5 were studied by means of energy dispersive X-rays (SEM + EDX), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Mössbauer spectroscopy (MS), as-quenched (a-q) and after annealing (a). EDX show agreement between the nominal and the measured atomic contents for all alloys. DSC provided three phase transition temperatures of the materials, MS spectra reveal amorphous structure of as-quenched alloys and a mixture of amorphous and crystalline structures of annealed alloys. The XRD spectra of annealed alloys allow us to resolve three crystalline phases of Fe. 相似文献
The purpose of the present study was to develop a model to describe the heat and mass transfer during the drying of carrot cubes in a spout-fluidized-bed drier. The model took into account the non-homogeneous shrinkage of the material. The Arbitrary Lagrange–Eulerian (ALE) formulation was applied to enter the problem with moving boundaries. Three phases of drying were distinguished according to the behavior of changes in percent local error of estimation: an initial phase of warming up the material – characterized by a low level of error of moisture content prediction, a second phase – characterized by an increase in the error of moisture content prediction and a phase of decreasing error. A simple test of the sensitivity of the model to the changes in heat transfer coefficient was performed in order to improve the ability of the model to predict the changes in moisture content and temperature of dried carrots. The predicted changes in both the moisture content and the temperature of carrot cubes during drying in a spout-fluidized-bed drier indicate that the model can be successfully applied to describe moisture content, temperature and deformation of dried particles in cases when the very high accuracy of moisture content and temperature prediction is not a crucial element of investigation of the drying process. 相似文献
A method is presented to determine the effective diffusivity from experimental drying kinetics as a time-dependent parameter. The method combines an analytical solution of Fick's equation in which the Fourier number is approximated using the empirical coefficients a and b with a semi-theoretical equation derived for quasi-stationary conditions. The resulting equation has been applied to calculate the effective diffusivity from literature data on the drying of tobacco lamina and sliced celery. The applicability of the method was confirmed by good agreement of calculated and experimental data. It was found that the effective diffusivity for tobacco lamina rises sharply from practically zero at the beginning of drying to a maximum of 9·10− 10 m2/s at 89 s, and then gradually decays with time of drying. The same trend was found for sliced celery, but the maximum of the effective diffusivity (1.6·10− 7 m2/min) was attained at 56 s. The exact definition of the effective diffusivity vs. drying time identifies two phases of drying: the first phase was characterized by the rising intensity of drying with the maximum at the end of this phase, followed by the phase of slow decrease in the intensity of moisture removal. The rising intensity of drying observed during the initial phase of the process can be explained by warming up of the dried material during the initial phase of drying. 相似文献
Interfacial stress transfer in a model hybrid composite has been investigated. An Sm3+ doped glass fibre and a high-modulus regenerated cellulose fibre were embedded in close proximity to each other in an epoxy resin matrix dumbbell-shaped model composite. This model composite was then deformed until the glass fibre fragmented. Shifts of the absolute positions of a Raman band from the cellulose fibre, located at 1095 cm−1, and a luminescence band from a doped glass fibre, located at 648 nm, were recorded simultaneously. A calibration of these shifts, for both fibres deformed in air, was used to determine the point-to-point distribution of strain in the fibres around the breaks in the glass fibre. Each break that occurred in the glass fibre during fragmentation was shown to generate a local stress concentration in the cellulose fibre, which was quantified using Raman spectroscopy. Using theoretical model fits to the data it is shown that the interfacial shear stress between both fibres and the resin can be determined. A stress concentration factor (SCF) was also determined for the regenerated cellulose fibre, showing how the presence of debonding reduces this factor. This study offers a new approach for following the micromechanics of the interfaces within hybrid composite materials, in particular where plant fibres are used to replace glass fibres. 相似文献
The SSITKA measurements were performed in the steady state of complete methane oxidation on the Pd/Al2O3 and Pt/Al2O3 catalysts. It was found that the number of intermediates and their average life-time on the catalyst surface changes with
the increase of reaction temperature. On the Pd/Al2O3 catalyst there is larger number of active centres than on Pt/Al2O3 catalyst which permits the course of methane oxidation at lower temperatures. 相似文献
Nanocrystalline titanium carbide embedded in an hydrogenated amorphous carbon matrix (nc-TiC/a-C:H) shows high hardness and Young's modulus together with low wear and low friction coefficient. In this paper, we report on the preparation of well adherent nc-TiC/a-C:H coatings ~ 5 μm thick on stainless steel substrates using a well balanced magnetic field configuration and only very low power RF bias on the substrate. Hardness and Young's modulus of these coatings are 43 GPa and 380 GPa, respectively. The mechanical properties – hardness and Young's modulus – measured from the coating's top reach the values obtained at optimized experiments where the unbalanced magnetic field configuration was used. A simple method of depth profiling suitable for evaluation of mechanical properties of several micrometers thick coatings is developed and employed. The paper reports on the depth profile analyses of the coating hardness, Young's modulus, composition and morphology. 相似文献
Transient behaviour of catalytic monolith converter with NOx storage is studied under conditions typical for automobiles with lean-burn engines (i.e., diesel and advanced gasoline ones). Periodical alternation of inlet concentrations is applied—NOx are adsorbed on the catalyst surface during a long reductant-lean phase (2–3 min) and then reduced to N2 within a short reductant-rich phase (2–6 s). Samples of industrial NOx storage and reduction catalyst of NM/Ba/CeO2/γ-Al2O3 type (NM = noble metal), washcoated on 400 cpsi cordierite substrate, are used in the study. Effects of the rich-phase length and composition on the overall NOx conversions are examined experimentally. Reduction of NOx by CO, H2 and unburned hydrocarbons (represented by C3H6) in the presence of CO2 and H2O is considered.
Effective, spatially 1D, heterogeneous mathematical model of catalytic monolith with NOx and oxygen storage capacity is described. The minimum set of experiments needed for the evaluation of relevant reaction kinetic parameters is discussed: (i) CO, H2 and HC oxidation light-off under both lean and rich conditions, including inhibition effects, (ii) NO/NO2 transformation, (iii) NOx storage, including temperature dependence of effective NOx storage capacity, (iv) water gas shift and steam reforming under rich conditions, i.e., in situ production of hydrogen, (v) oxygen storage and reduction, including temperature dependence of effective oxygen storage capacity, and (vi) NOx desorption and reduction under rich conditions. The experimental data are compared with the simulation results. 相似文献
Summary When certain amounts of starch were blended with saturated, aqueous solutions of d-fructose, d-glucose or sucrose, shear thickening, easily pourable semi-solids were formed. The amount of starch necessary to cause this rheological effect depended, at least in part, on the starch variety. The conditions necessary to observe this effect using potato and corn starch blends with d-fructose, d-glucose and sucrose are presented. This method may be useful in studies of starch granule morphology. Gelation characteristics and differential scanning calorimetry (DSC) of potato and corn starch in saturated aqueous d-fructose, d-glucose, and sucrose solutions showed that both starch varieties interacted differently with the environment. Starch more readily gelatinised in sucrose solutions than in solutions of d-fructose and d-glucose. 相似文献