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931.
Tadeusz Błaszczyk Danuta Kaźmierczak Pawel Krzyczmonik Henryk Scholl Krzysztof Polański 《Journal of Solid State Electrochemistry》2000,4(2):95-106
The oxidation of cobalt electrodes has been carried out by means of cyclic voltammetry and coulometry under controlled potential
in sulfuric acid solutions of different concentrations. The electrochemical scanning tunneling microscope/scanning tunneling
microscope (ECSTM/STM) systems constructed by the authors and scanning electron microscopy (SEM) with the SEM-EDX system of
surface analysis of the elements have been used. The procedure applied in this work made it possible to observe the fragments
of the same surface by means of SEM and ECSTM/STM. The most typical images for a polycrystalline Co electrode with a ±10%
accuracy at the scales of 4800 nm × 4800 nm and 100 nm × 100 nm are presented and the results are discussed. In a diluted
electrolyte (0.1 M), irregular forms of a stable cobalt oxide with Co:O ratio ∼1:1 appear. Unreproducible results have been
obtained in a 1.0 M H2SO4 solution. Compact and relatively regular layers of cobalt oxide of the same ratio have been obtained in 0.1 M H2SO4, as well as in 10.0 M sulfuric acid solution, under controlled oxidation potential at the passivation range.
Received: 6 January 1999 / Accepted: 5 May 1999 相似文献
932.
Łysek R Borsuk K Chmielewski M Kałuza Z Urbańczyk-Lipkowska Z Klimek A Frelek J 《The Journal of organic chemistry》2002,67(5):1472-1479
The relationship between chiroptical properties of differently substituted 5-dethia-5-oxacephams and their respective molecular structures was investigated. The amide chromophore of the beta-lactam unit in these compounds was found to be nonplanar with a shallow pyramidal configuration at the nitrogen atom. Due to the nonplanarity, the beta-lactam system becomes inherently dissymmetric, which is supported by a high magnitude of the n --> pi* CD band. It was also found that the helicity of the lactam moiety in investigated oxacephams is controlled by the absolute configuration at the C(6) carbon atom. On this basis, a helicity rule correlating a positive (negative) sign of the n right arrow pi Cotton effect with a negative (positive) O [double bond] C [bond] N [bond] C(6) torsional angle for policyclic beta-lactam derivatives possessing a nonplanar amide chromophore was formulated. 相似文献
933.
Vlastimil Matějec Miloš Hayer Marie Pospíšilová Ivan KaŠík 《Journal of Sol-Gel Science and Technology》1997,8(1-3):889-893
Preforms for drawing silica optical fibers have been fabricated by using the MCVD method for the preparation of the optical
claddings and the sol-gel method for the preparation of the optical cores consisting of TiO2−SiO2 or RE3+−Al2O3−P2O5−SiO2 (RE=Er, Yb) glasses. A novel method has been developed for depositing thin gel layers on the inner silica tube wall, under
rotation of the tube inclined at a small angle to the horizontal. The gel layers have been deposited from sols prepared by
mixing Si(OC2H5)4, POCl3, Ti(n-OC4H9)4, AlCl3, ErCl3, YbCl3 H2O, C2H5OH and HCl. The gel layers deposited using these sols on the inner tube wall were heat-treated in a flow of CCl4 or POCl3 with O2 at temperatures of from 800° to 1400°C. After collapsing the composite tube into a preform, an optical fiber has been drawn.
The refractive-index profiles of the preforms and the attenuation spectra of the drawn fibers are shown, as well as some results
on the lasing characteristics of Yb3+ sensitized, Er3+ doped fibers. 相似文献
934.
Mikšík I Lacinová K Zmatlíková Z Sedláková P Král V Sýkora D Rezanka P Kašička V 《Journal of separation science》2012,35(8):994-1002
In this work, open-tubular capillary electrochromatography (OT-CEC) method with bare gold nanoparticles (GNPs)-based stationary phase has been developed and applied for separation of tryptic peptide fragments of native and glycated proteins, bovine serum albumin (BSA), and human transferrin (HTF). The GNPs-based stationary phase was prepared by immobilization of bare GNPs, freshly reduced from tetrachloroaurate(III) ions by citrate reduction, on the sol-gel pretreated inner wall of the fused silica capillary. The separation efficiency, peak capacity, and peptide recovery of this open-tubular capillary column were investigated by varying the experimental parameters such as type and concentration of the buffering constituent and pH of the background electrolyte (BGE), temperature, and separation voltage. The best separations of the above tryptic peptides were achieved in the BGE composed of aqueous 100 mmol/L sodium phosphate buffer, pH 2.5, at separation voltage 10 kV per 47-cm long, 50 μm inside diameter capillary thermostated at 25°C. OT-CEC with bare GNPs stationary phase is shown to be a suitable technique for separation of complex peptide mixtures arising from tryptic digestion of native and glycated BSA and HTF, and for investigation of glycation (nonenzymatic glycosylation) of these proteins. 相似文献
935.
使用GTEM Cell实验系统,研究了连续波电磁辐射对基于混沌同步理论的保密通信系统的电磁干扰。混沌保密通信系统采用由典型的Chua氏混沌电路构造混沌同步系统,采用掩盖法对模拟信号进行加密传输。实验发现:在100MHz~150MHz的频率范围内,超过一定功率密度的电磁辐射会导致系统的混沌加密功能失效,此后即使停止电磁辐射,系统仍无法自行恢复到混沌加密状态。 相似文献
936.
This Note is concerned with the links between nonlinear stabilization of hyperbolic systems and linear observability for the unforced corresponding linear system, for locally distributed and boundary feedbacks as well. We show that if the linear system is observable through a locally distributed (resp. boundary) observation, then any dissipative nonlinear feedback locally distributed (resp. active only on a part of the boundary) stabilize the system and we give a general energy decay formula. Our results generalize previous results by Haraux (1989) and Ammari and Tucsnak (2001) for linear feedbacks. We show by this way that for the locally distributed case, one can combine the optimal geometric conditions of Bardos et al. (1992) and the method of Alabau-Boussouira (2005) to deduce energy decay rates for nonlinear damped systems. 相似文献
937.
Let (E,E′) be a dual pair of vector spaces. The paper studies general conditions which allow to lift analyticity (or K-analyticity) from the weak topology σ(E,E′) to stronger ones in the frame of (E,E′). First we show that the Mackey dual of a space Cp(X) is analytic iff the space X is countable. This yields that for uncountable analytic spaces X the Mackey dual of Cp(X) is weakly analytic but not analytic. We show that the Mackey dual E of an (LF)-space of a sequence of reflexive separable Fréchet spaces with the Heinrich density condition is analytic, i.e. E is a continuous image of the Polish space NN. This extends a result of Valdivia. We show also that weakly quasi-Suslin locally convex Baire spaces are metrizable and complete (this extends a result of De Wilde and Sunyach). We provide however a large class of weakly analytic but not analytic metrizable separable Baire topological vector spaces (not locally convex!). This will be used to prove that analyticity is not a three-space property but we show that a metrizable topological vector space E is analytic if E contains a complete locally convex analytic subspace F such that the quotient E/F is analytic. Several questions, remarks and examples are included. 相似文献
938.
TiO2/SiOx double-layers have been prepared at room temperature by RF magnetron sputtering. The TiO2 top-layer was deposited in an Ar atmosphere, while the SiOx bottom-layer was deposited in an Ar/O2 atmosphere. Samples were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and photoluminescence techniques. The photocatalytic activity of the samples was evaluated by the photodegradation of methylene blue; the results showed that the photocatalytic activity of the TiO2/SiOx double-layers was superior to that of the TiO2 single-layers. The presence of the SiOx bottom-layer improved the photocatalytic activity of the TiO2 layer because it may act as a trap for electrons generated in the TiO2 layer thus preventing electron-hole recombinations. 相似文献
939.
We derive the inequality $$\int_\mathbb{R}M(|f'(x)|h(f(x))) dx\leq C(M,h)\int_\mathbb{R}M\left({\sqrt{|f''(x)\tau_h(f(x))|}\cdot h(f(x))}\right)dx$$ with a constant C(M, h) independent of f, where f belongs locally to the Sobolev space ${W^{2,1}(\mathbb{R})}$ and f′ has compact support. Here M is an arbitrary N-function satisfying certain assumptions, h is a given function and ${\tau_h(\cdot)}$ is its given transform independent of M. When M(λ) = λ p and ${h \equiv 1}$ we retrieve the well-known inequality ${\int_\mathbb{R}|f'(x)|^{p}dx \leq (\sqrt{p - 1})^{p}\int_\mathbb{R}(\sqrt{|f''(x) f(x)|})^{p}dx}$ . We apply our inequality to obtain some generalizations of capacitary estimates and isoperimetric inequalities due to Maz’ya (1985). 相似文献
940.
Guoyin Li Alfred Ka Chun Ma Ting Kei Pong 《Computational Optimization and Applications》2014,58(2):347-379
In this paper, we consider a least square semidefinite programming problem under ellipsoidal data uncertainty. We show that the robustification of this uncertain problem can be reformulated as a semidefinite linear programming problem with an additional second-order cone constraint. We then provide an explicit quantitative sensitivity analysis on how the solution under the robustification depends on the size/shape of the ellipsoidal data uncertainty set. Next, we prove that, under suitable constraint qualifications, the reformulation has zero duality gap with its dual problem, even when the primal problem itself is infeasible. The dual problem is equivalent to minimizing a smooth objective function over the Cartesian product of second-order cones and the Euclidean space, which is easy to project onto. Thus, we propose a simple variant of the spectral projected gradient method (Birgin et al. in SIAM J. Optim. 10:1196–1211, 2000) to solve the dual problem. While it is well-known that any accumulation point of the sequence generated from the algorithm is a dual optimal solution, we show in addition that the dual objective value along the sequence generated converges to a finite value if and only if the primal problem is feasible, again under suitable constraint qualifications. This latter fact leads to a simple certificate for primal infeasibility in situations when the primal feasible set lies in a known compact set. As an application, we consider robust correlation stress testing where data uncertainty arises due to untimely recording of portfolio holdings. In our computational experiments on this particular application, our algorithm performs reasonably well on medium-sized problems for real data when finding the optimal solution (if exists) or identifying primal infeasibility, and usually outperforms the standard interior-point solver SDPT3 in terms of CPU time. 相似文献