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83.
Robert Kun Sndor Tarjn Albert Oszk Torben Seemann Volker Zllmer Matthias Busse Imre Dkny 《Journal of solid state chemistry》2009,182(11):3076-3084
Nitrogen-doped TiO2 catalysts were prepared by a precipitation method. The samples were calcined at 400 °C for 4 h in air. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature N2-adsorption was used for structural characterization and UV-diffuse reflectance (UV-DR) was applied to investigate the optical properties of the as-prepared samples. It was found that microporous N-doped catalysts have solely anatase crystalline structure. Acidic treatment of the calcined samples was performed using sulfuric acid agitation. The crystalline structure remained unchanged due to surface treatment, while the porosity and the surface areas were decreased dramatically. Optical characterization of the doped catalysts showed that they could be excited by visible light photons in the 400–500 nm wavelength range (λg,1=390 nm, λg,2=510 nm). It was also established that surface treatment enhances the Vis-light absorption of the N-TiO2 powders. Finally the catalysts were tested in the photocatalytic degradation of phenol in aqueous suspensions. Two different light sources were used; one of them was a UV-rich high pressure Hg-lamp, while the other was a tubular visible light source. We found that using visible light illumination N-doped, acid treated TiO2 samples were more catalytically active than non-doped TiO2 catalysts. 相似文献
84.
We report on the direct observation of the transition from a compressible superfluid to an incompressible Mott insulator by recording the in-trap density distribution of a Bosonic quantum gas in an optical lattice. Using spatially selective microwave transitions and spin-changing collisions, we are able to locally modify the spin state of the trapped quantum gas and record the spatial distribution of lattice sites with different filling factors. As the system evolves from a superfluid to a Mott insulator, we observe the formation of a distinct shell structure, in good agreement with theory. 相似文献
85.
86.
Darden SK Pedersen SB Larsen ON Dabelsteen T 《The Journal of the Acoustical Society of America》2008,124(2):758-766
The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effect of propagation on individual identity information in vocalizations were quantified in a transmission experiment in prairie habitat. Sounds were propagated (0.45 m above the ground) at distances up to 400 m. Effects of transmission were measured on three sound types: synthesized sweeps with 1.3 kHz bandwidths spanning in the range of 0.3-8.0 kHz; single elements of swift fox barking sequences (frequency range of 0.3-4.0 kHz) and complete barking sequences. Synthesized sweeps spanning 0.3-1.6 and 1.2-2.5 kHz propagated the furthest and the latter sweeps exhibited the best transmission properties for long-range propagation. Swift fox barking sequence elements are centered toward the lower end of this frequency range. Nevertheless, measurable individual spectral characteristics of the barking sequence seem to persist to at least 400 m. Individual temporal features were very consistent to at least 400 m. The communication range of the barking sequences is likely to be farther than 400 m and it should be considered a long-ranging vocalization. However, relative to the large home ranges of swift foxes (up to 16 km(2) in the experimental area) the barking sequence probably functions at intermediate distances. 相似文献
87.
Bent F. Sørensen Stergios Goutianos Torben K. Jacobsen 《International Journal of Solids and Structures》2009,46(3-4):741-761
The fracture of adhesive joints between two glass-fibre laminates was studied by testing double cantilever beam test specimens loaded by uneven bending moments. A large-scale fracture process zone, consisting of a crack tip and a fibre bridging zone, developed. The mixed mode fracture resistance increased with increasing crack length, eventually reaching a steady-state level (R-curve behaviour). The steady-state fracture resistance level increased with increasing amount of tangential crack opening displacement. Cohesive laws, obtained from fracture resistance data, were used for prediction the load carrying capacity of 2-m long “medium size” adhesive joint specimens subjected to four point flexure. Medium size specimens were manufactured and tested. A good agreement was found between the predicted and measured strength values of the medium-size specimens. Thus, the scaling from small specimens to medium-size specimens was successfully achieved. 相似文献
88.
Torben Maack Bisgaard 《Journal of Theoretical Probability》1990,3(1):71-80
A sequence : 0 satisfiesHoeffding's inequality of order n if wheneverX
1,...,X
n are independent nonnegative integer-valued elementary random variables and
are independent identically distributed nonnegative integer-valued elementary random variables, the common distribution of which is the average of those ofX
1,...,X
n. We show that for each integerm greater than 2 there exists a sequence satisfying Hoeffding's inequality of every order greater thanm but not that of orderm. This answers a question raised by Berg, Christensen, and Ressel. 相似文献
89.
23种挥发性有机化合物在3种吸附剂上漏出容量的测定评价 总被引:4,自引:0,他引:4
采用吸附热解吸-气相色谱-质谱法对23种挥发性有机化合物Chromosorb 106、Tenax TA、Tenax TG等3种吸附剂上漏出容量进行了测定。根据实验结果确定了不同的化合物应选择不同的吸附剂及相应的采样体积。结果表明,Chromosorb 106可较好地吸附低沸点的挥发性有机化合物,Tenax TA、Tenax TG均可用于沸点较高的挥发笥有机化合物吸附,这对测定大气中的有机化合物含量采样有一定的参考价值。 相似文献
90.
Edit Pál Torben Seemann Volker Zöllmer Matthias Busse Imre Dékány 《Colloid and polymer science》2009,287(4):481-485
Zinc oxide/poly(acrylic acid) (ZnO/PAA) multilayered hybrid films with different layer thicknesses were prepared by radio
frequency magnetron sputtering. Zinc peroxide was used as precursor materials for the preparation of ZnO layers, since the
zinc peroxide decomposes to ZnO during the film deposition. The films have a high transmittance in the visible region and
exhibit visible photoluminescence emission. The band gap energy of the films—determined by the Tauc relationship—decreases
with increasing layer thickness (3.40–3.36 eV) due to the increasing crystalline size of the ZnO particles. The morphological
investigations showed that a real layered hybrid film structure formed. 相似文献