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41.
X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) have been used to investigate the effect of reactive ion etching (RIE) on poly(methylhydrogensiloxane-co-dimethylsiloxane) surface in fluorine-based plasmas. Polysiloxane layers supported on the standard silicon wafers were etched using SF6 + O2 or CF4 + O2 plasmas. SEM studies show that the polysiloxane morphology depends on plasma chemical composition strongly. Presence of a columnar layer likely covered with a fluorine rich compound was found on the elastomer surface after the CF4 + O2 plasma exposure. After the SF6 + O2 or CF4 + O2 plasma treatment the polysiloxane surface enriches with fluorine or with fluorine and aluminum, respectively. Different morphologies and surface chemical compositions of the silicone elastomer etched in both plasmas indicate different etching mechanisms. 相似文献
42.
We study Fourier multipliers which result from modulating jumps of Lévy processes. Using the theory of martingale transforms we prove that these operators are bounded in Lp(Rd) for 1<p<∞ and we obtain the same explicit bound for their norm as the one known for the second order Riesz transforms. 相似文献
43.
We describe phenomena occurring just before a saddle-node bifurcation for one-parameter families of interval maps. In particular, as a parameter approaches the bifurcation value, attracting periodic orbits of periodsk, k+1,k+2,k+3,... can appear. We make a detailed study of a family of cusp-shaped maps, where this phenomenon occurs in a pure form. 相似文献
44.
Dr. A. Kaczyński Dr. S. J. Matysiak 《Archive of Applied Mechanics (Ingenieur Archiv)》1988,58(2):137-147
Summary This paper deals with the two-dimensional static punch problems in the presence of friction for a periodically layered half-space. Within the framework of the homogenized model of linear elasticity with microlocal parameters [8–11] the exact solutions of the considered problems are obtained. The case of the indentation of the composite body by a rigid rectangular punch has been discussed in detail.
Ebene Kontaktprobleme für ein periodisches elastisches Zweischichten-Komposit
Übersicht In dieser Arbeit wird das zweidimensionale statische Stempelproblem mit Reibung für einen periodisch geschichteten Halbraum betrachtet. Im Rahmen eines Homogenisierungsmodells der linearen Elastizitätstheorie mit mikropolaren Parametern werden die exakten Lösungen der betrachteten Probleme gewonnen. Im Detail wird das Eindringen eines rechteckigen starren Stempels behandelt.相似文献
45.
Margaret C. Etter Zofia Urbańczyk-Lipkowska Touradj M. Ameli Thomas W. Panunto 《Journal of chemical crystallography》1988,18(5):491-507
The crystal structures, solid-state infrared patterns, and thermal properties of two polymorphs of 4-nitrosalicylanilide are presented. In both polymorphs, intramolecular hydrogen bonds are found between the phenol oxygen and the amide proton, and intermolecular hydrogen bonds are found between the amide carbonyl oxygen and the phenol proton. These hydrogen bond patterns are compared to those found in other known salicylamide derivatives and an analysis is given of the factors contributing to preferences for intra- or intermolecular hydrogen bonds in these structures. Crystal data: polymorph, orthorhombic,Pbca,a=11.003(4),b=27.959(7),c=7.622(5) Å,Z=4,V=2345(3) Å3, andR=0.038 (1351 reflections); polymorph, monoclinic,P21/a,a=28.36(1),b=11.64(1),c=7.293(8) Å,=90.68(6)°,Z=8,V=2408 Å3, andR=0.043 (2425 reflections). 相似文献
46.
Creep resistance investigations of the Al-40 wt % Zn alloy at room temperature have been performed and revealed some creep compliance. Additions of Cu and Si decrease considerably the preliminary creep compliance in the alloy which then turn to be dimensionally stable and resistant to creep. Tensile test investigations performed at different deformation rates have not revealed the existance of the superplastic deformation mechanism.Presented at the 4th International Symposium on Plasticity of Metals and Alloys, September 711, 1987, Srni, Czechoslovakia. 相似文献
47.
48.
Ion-selective electrode with cellulose triacetate membrane containing nonactin is employed for the potentiometric detection of ammonia produced in biocatalytic reaction in flow-injection system with enzyme reactor. The elimination of interferences occurring in the presence of alkali metal ions was achieved by covering a nonactin membrane with outer hydrophobic gas permeable membrane. The obtained flow-injection response to ammonia indicates a possibility of ammonia determination down to 10 microM ammonia. In the flow-injection system for urea determination 200 microl of 10-fold diluted blood serum sample was injected into carrier stream of distilled water merged with TRIS buffer, passed through the urease flow-through reactor and then after merging with NaOH stream delivered to the detector. It was found in several series of natural blood serum samples, that the correction for endogenous ammonia in such a determination is not indispensable. 相似文献
49.
Suńol J. J. Saurina J. Carrillo F. Colom X. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):753-758
Comparison of Lyocell, modal and viscose fibers was performed by means of differential scanning calorimetry, thermogravimetry
and scanning electron microscopy. Thermal analysis was performed in air atmosphere. Samples were mercerized (21.3 g 100 mL-1)
or submitted to solar radiation (seven months). Solar degraded samples presents a higher thermal stability and are initially
less degraded. Furthermore, Lyocell fiber is the most stable under thermal degradation conditions. Heating produces a reduction
of the fiber diameter (about 50%).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
PHOTOCYTOTOXICITY OF CURCUMIN 总被引:5,自引:0,他引:5
Thomas A. Dahll Piotr Bilski Krzysztof J. Reszka Colin F. Chignell 《Photochemistry and photobiology》1994,59(3):290-294
Curcumin, bis (4-hydroxy-3-methoxyphenyl)-l,6-diene-3,5-dione, is a yellow-orange dye derived from the rhizome of the plant Curcuma longa. Curcumin has demonstrated phototoxicity to several species of bacteria under aerobic conditions (Dahl, T. A., et al. , 1989, Arch. Microbiol. 151 183), denoting photodynamic inactivation. We have now found that curcumin is also phototoxic to mammalian cells, using a rat basophilic leukemia cell model, and that this phototoxicity again requires the presence of oxygen. The spectral and photochemical properties of curcumin vary with environment, resulting in the potential for multiple or alternate pathways for the exertion of photodynamic effects. For example, curcumin photogenerates singlet oxygen and reduced forms of molecular oxygen under several conditions relevant to cellular environments. In addition, we detected carbon-centered radicals, which may lead to oxidation products (see accompanying paper). Such products may be important reactants in curcumin's phototoxicity since singlet oxygen and reduced oxygen species alone could not explain the biological results, such as the relatively long lifetime (t12 = 27 s) of the toxicant responsible for decreased cell viability. 相似文献