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21.
The 3D profile surface parameter H
q
and fractal dimension D were tested as indicators of mechanical properties inferred from fracture surfaces of porous solids. High porous hydrated
cement pastes were used as prototypes of porous materials. Both the profile parameter H
q
and the fractal dimension D showed capability to assess compressive strength from the fracture surfaces of hydrated pastes. From a practical point of
view the 3D profile parameter H
q
seems to be more convenient as an indicator of mechanical properties, as its values suffer much less from statistical scatter
than those of fractal dimensions. 相似文献
22.
Jérôme Dedecker Florence Merlevède Dalibor Volný 《Journal of Theoretical Probability》2007,20(4):971-1004
In this paper we study the central limit theorem and its weak invariance principle for sums of non-adapted stationary sequences,
under different normalizations. Our conditions involve the conditional expectation of the variables with respect to a given
σ-algebra, as done in Gordin (Dokl. Akad. Nauk SSSR 188, 739–741, 1969) and Heyde (Z. Wahrsch. verw. Gebiete 30, 315–320, 1974). These conditions are well adapted to a large variety of examples, including linear processes with dependent innovations
or regular functions of linear processes. 相似文献
23.
Dalibor Froncek 《Graphs and Combinatorics》2007,23(2):145-163
An orthogonal double cover (ODC) of the complete graph Kn by a graph G is a collection = {Gi|i = 1,2, . . . ,n} of spanning subgraphs of Kn, all isomorphic to G, with the property that every edge of Kn belongs to exactly two members of and any two distinct members of share exactly one edge.
A caterpillar of diameter five is a tree arising from a path with six vertices by attaching pendant vertices to some or each
of its vertices of degree two. We show that for any caterpillar of diameter five there exists an ODC of the complete graph
Kn. 相似文献
24.
Simple,Rapid and Sensitive Electrochemical Method for the Determination of the Triketone Herbicide Sulcotrione in River Water Using a Glassy Carbon Electrode
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We report a novel, simple, rapid and sensitive electrochemical method for the determination of sulcotrione, a member of the relatively new class of triketone herbicides, using differential pulse voltammetry on a glassy carbon electrode. Its electrochemical behavior including influences of electrolyte composition, pH and scan rate was studied to select optimal experimental parameters for its determination. In Britton? Robinson buffer at pH 3 sulcotrione provided a well‐defined reduction peak at ?0.84 V (vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.3 % for 8 measurements at 10 µM concentration level). With optimized parameters differential pulse voltammetry rendered two linear concentration ranges from 0.2 to 2 µM and from 2 to 50 µM with a detection limit of 0.05 µM. The proposed procedure was successfully applied to the determination of sulcotrione in spiked river water samples with satisfactory recoveries (93–109 %). The developed method may represent a simple, rapid and sensitive alternative to highly toxic mercury electrodes and chromatographic methods. 相似文献
25.
Dalibor Huska Vojtech Adam Petr Babula Libuse Trnkova Jaromir Hubalek Josef Zehnalek Ladislav Havel Rene Kizek 《Mikrochimica acta》2011,173(1-2):189-197
The expression of genes responsible for the biosynthesis of stress proteins corresponds to the exposition of an organism to abiotic and/or biotic stress. We utilize two types of paramagnetic particles for isolation of total mRNA from early somatic embryos of Norway Spruce (Picea abies /L./ Karst.) and maize plants (Zea mays L.) treated with cadmium(II) ions. The paramagnetic particles were evaluated for analysis of real samples, and poly-adenine was used as a model mRNA. Various approaches (from non-automatic to fully automatic) were tested in terms of handling the particles. Figa
Microfluidic robotic device coupled with electrochemical sensor field 相似文献
26.
Dalibor Stankovic Dragan Manojlovic Goran Roglic Sladjana Kostic‐Rajacic Ivan Andjelkovic Biljana Dojcinovic Jelena Mutic 《Electroanalysis》2011,23(8):1928-1933
The determination of Pb and Cd with a Nafion‐modified glassy carbon electrode and Cu‐DPABA complex (Cu‐DPABA–NA/GCE; DPABA is methyl 3,5‐bis{bis‐[(pyridin‐2‐yl)methyl]amino}methyl‐benzoate) as an alternative electrode for anodic stripping voltammetry was described. Pb and Cd were accumulated in acetate buffer pH 4 at a potential of ?1.4 V (vs. Ag/AgCl electrode) for 120 s followed by a DPASV scan from ?1.2 to ?0.2 V. Under optimum conditions the calibration curves were linear in the range of 4.8×10?9–5.0×10?5 and 5.0×10?9–5×10?5 mol L?1 for Pb and Cd, respectively. Detection limits were 1.8×10?9 and 1.2×10?9 mol L?1 for Pb and Cd, respectively. Different parameters and conditions, such as membrane ingredients, accumulation time, potential and pH value were optimized. A study of interfering substances was also performed. A significant increase in current was achieved at the modified electrode in comparison with the bare glassy carbon electrode. The validation of the proposed method was made by Pb and Cd determination in the certified reference material Groundwater CRM 610 (BCR, Community Bureau of Reference, Brussels, Belgium). The electrode was successfully applied for determination of Pb and Cd in river water with a high content of organic contaminants without any pretreatment. 相似文献
27.
Dyer J Jockusch S Balsanek V Sames D Turro NJ 《The Journal of organic chemistry》2005,70(6):2143-2147
[reaction: see text] Two-photon induced Wolff rearrangement of a terphenyl diazoketone 1 was achieved by using focused laser pulses of 532 nm from a Q-switched Nd:YAG laser. The nonfluorescent terphenyl diazoketone 1 was transformed into a fluorescent ester derivative 4, which can be detected in situ using the focused laser pulses at 532 nm. Laser power dependence studies show that the Wolff rearrangement is induced by two-photon absorption of the terphenyl diazoketone 1, but suggests that more than two photons of 532 nm are involved (a multiphoton process) in excitation of the ester derivative 4. 相似文献
28.
Dalibor Lukáš Günther Of Jan Zapletal Jiří Bouchala 《Mathematical Methods in the Applied Sciences》2020,43(3):1035-1052
Homogenized coefficients of periodic structures are calculated via an auxiliary partial differential equation in the periodic cell. Typically, a volume finite element discretization is employed for the numerical solution. In this paper, we reformulate the problem as a boundary integral equation using Steklov–Poincaré operators. The resulting boundary element method only discretizes the boundary of the periodic cell and the interface between the materials within the cell. We prove that the homogenized coefficients converge super-linearly with the mesh size, and we support the theory with examples in two and three dimensions. 相似文献
29.
NURBS (Non-Uniform Rational B-Splines) belong to special approximation curves and surfaces which are described by control
points with weights and B-spline basis functions. They are often used in modern areas of computer graphics as free-form modelling,
modelling of processes. In literature, NURBS surfaces are often called tensor product surfaces. In this article we try to
explain the relationship between the classic algebraic point of view and the practical geometrical application on NURBS. 相似文献
30.
Catalytic C-H arylation of SEM-protected azoles with palladium complexes of NHCs and phosphines 总被引:1,自引:0,他引:1
[reaction: see text] The synthesis and catalytic evaluation of palladium complexes containing imidazolyl carbene ligand of varying steric and electronic properties is reported. These complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines. The reaction is operationally simple; the complexes are insensitive to moisture. 相似文献