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61.
Eva Klimánková Kateřina Holadová Jana Hajšlová Tomáš Čajka Jan Poustka Martin Koudela 《Food chemistry》2008
A headspace solid-phase microextraction (HS-SPME) method coupled to gas chromatography–ion trap mass spectrometry (GC–ITMS) has been developed and applied for profiling of volatile compounds released from five Ocimum basilicum L. cultivars grown under both organic and conventional conditions. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOFMS) was employed for confirmation of identity of volatiles extracted from the basil headspace by SPME. 相似文献
62.
Jana Dulle Silke Nemeth Ekaterina V. Skorb Torsten Irrgang Jürgen Senker Rhett Kempe Andreas Fery Daria V. Andreeva 《Advanced functional materials》2012,22(15):3128-3135
This paper proposes a sonochemical approach to the nanostructuring of Al/Ni catalyst with high content of accessible Ni centers and a high reusability. The surface and bulk composition as well as pore size distribution of this catalyst are controlled synergistically by adjusting the ultrasound intensity in aqueous solution. Sonochemical activation of Al/Ni alloy leads to formation of mesoporous Al/Ni metallic based frameworks with surface area up to 125 m2 g?1, and regular distribution of nickel active center in the porous matrix. One of the opportunities of porous Al/Ni catalyst is that due to a time‐resolved controllable formation of protective oxide layer it can be stored and handled under air in comparison to traditional Raney catalysts which need inert conditions. The Al/Ni catalyst is characterized by scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS), X‐ray photoelectron spectroscopy (XPS), confocal scanning fluorescence microscopy (CSFM), solid‐state NMR experiments, and powder X‐ray diffraction analysis (PXRD). The catalytic activity was investigated for the hydrogenation of acetophenone. 相似文献
63.
64.
Jana Velde Ursula Kowalsky Tim Zümendorf Dieter Dinkler 《Computational Materials Science》2009,46(2):352-357
In order to describe the time-dependent inelastic behavior of steel structures up to failure, a material model is developed within the framework of thermodynamics considering viscoplastic material behavior, isotropic hardening, softening, and isotropic ductile damage. Since softening and damage lead to localization of deformations, the model is extended by a non-local implicit gradient formulation. An additional gradient equation is formulated for the local damage variable in order to achieve results independent of the finite-element discretization. The approach is verified by 3D-structural analysis of CT-specimens. 相似文献
65.
Anton Trník Igor Štubňa Jana Moravčíková 《International Journal of Thermophysics》2009,30(4):1323-1328
The sound velocity of Sedlec kaolin during heating from 20 °C to 1100 °C was investigated by modulated force thermomechanical
analysis (mf-TMA). In the interval from 20 °C to 250 °C, the sound velocity increases which can be explained by liberation
of the water molecules from pores and micropores. Dehydroxylation (450 °C to 650 °C) presents itself with a decrease of the
sound velocity. After dehydroxylation, a two-step increase of the sound velocity was observed. The first step of the increase
of the sound velocity is due to solid-state sintering at low temperatures. The second step starts at 950 °C as a consequence
of the collapse of the metakaolinite structure. After the maximum, a steep increase of the sound velocity follows as a result
of solid-state sintering. 相似文献
66.
Jana Urban Joemon M. Jose Cornelis J. van Rijsbergen 《Multimedia Tools and Applications》2006,31(1):1-28
We discuss an adaptive approach towards Content-Based Image Retrieval. It is based on the Ostensive Model of developing information needs—a special kind of relevance feedback model that learns from implicit user feedback and adds a temporal notion to relevance. The ostensive approach supports content-assisted browsing through visualising the interaction by adding user-selected images to a browsing path, which ends with a set of system recommendations. The suggestions are based on an adaptive query learning scheme, in which the query is learnt from previously selected images. Our approach is an adaptation of the original Ostensive Model based on textual features only, to include content-based features to characterise images. In the proposed scheme textual and colour features are combined using the Dempster-Shafer theory of evidence combination. Results from a user-centred, work-task oriented evaluation show that the ostensive interface is preferred over a traditional interface with manual query facilities. This is due to its ability to adapt to the user's need, its intuitiveness and the fluid way in which it operates. Studying and comparing the nature of the underlying information need, it emerges that our approach elicits changes in the user's need based on the interaction, and is successful in adapting the retrieval to match the changes. In addition, a preliminary study of the retrieval performance of the ostensive relevance feedback scheme shows that it can outperform a standard relevance feedback strategy in terms of image recall in category search. 相似文献
67.
A transmission electron microscopy and diffraction study of martensite plates in an Fe-3 pct Mn-3 pct Cr-1 pct C alloy was carried out with particular attention to details of the martensite substructure. A corresponding optical metallographic study of plate morphology was made. A variability in martensite substructure was observed from plate to plate, although a (252)F * plate was generally associated with (112)B transformation twins and {111}F stacking faults. The particular (111)F fault variant gave rise to a wedge-shaped plate morphology. Planar {101}B inhomogeneities were frequently observed in the martensite, and most of these appear to be derived from austenite stacking faults. In general, more than one type of inhomogeneity was observed in a single martensite plate and the “typical” plate substructure was rather difficult to characterize, although the habit plane was found invariably to be (252)F. 相似文献
68.
Toxicity increases in ice containing monochlorophenols upon photolysis: environmental consequences 总被引:4,自引:0,他引:4
Bláha L Klánová J Klán P Janosek J Skarek M Růzicka R 《Environmental science & technology》2004,38(10):2873-2878
The toxic effects of photoproducts formed upon the photolysis of 2- and 4-chlorophenol (CP) frozen solutions in polycrystalline ice phase were determined with a bacterial luminescence test (Vibrio fisheri), and in vitro biomarker assay for dioxin-like effects (inductions of AhR-dependent luciferase in H4IIE-luc cells) and compared to the toxic effects of products of the same photoreaction in aquatic phase. Coupling photoproducts formed in ice samples (3'-chlorobiphenyl-2,4'-diol and 3-chlorobiphenyl-2,2'-diol from 2-CP photolysis and 5-chlorobiphenyl-2,4'-diol from 4-CP photolysis) were found to be more toxic to V. fisheri than parent CPs and elicited significant inductions of dioxin-like effects (the effective concentrations EC50 approximately 3 x 10(-5) mol L(-1) corresponded to known weaker ligands of AhR, such as nonplanar polychlorinated biphenyls or polycyclic aromatic hydrocarbons). To complete the picture, a photoproduct formed from 4-CP (5-chlorobiphenyl-2,4'-diol) was synthesized, and a detailed toxicity assessment with purified compound confirmed the results obtained with irradiated samples. Our findings support a recently proposed model according to which solar radiation can trigger the formation of new types of organic pollutants in polar ice or tropospheric ice cloud particles, presenting possibly greater risk to the environment than the parent compounds. 相似文献
69.
70.
We propose a method for representing heterogeneous concept lattices as classical concept lattices. Particularly, we describe a transformation of heterogeneous formal context into a binary one, such that corresponding concept lattices will be isomorphic. We prove the correctness of this transformation by the basic theorem for heterogeneous as well as classical concept lattices. 相似文献