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
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
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.
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
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
In this paper, several methods of hydrophobization of cotton fabrics using the thio-ene click reaction were compared. Durable, superhydrophobic textiles were obtained in an easy way. Various variants of functionalized silsesquioxanes were used for the hydrophobization of fabrics. The synthesis of bifunctional silsesquioxanes (RSiMe2O)4(ViSiMe2O)4Si8O12 and (RSiMe2O)4(R’SiMe2O)4Si8O12 were performed via hydrothiolation of silsesquioxane derivative (ViSiMe2O)8Si8O12. Alkoxysilyl, alkyl and fluoroalkyl moieties were introduced as functional groups. Samples were prepared using four methods, differing in the modification method and the number of stages. During the research, fabrics were modified via (a) the dip-coating process, (b) carrying out thiol-ene click reactions directly on the surface of the fabric and (c) using both of these methods. The hydrophobicity of the fabric was evaluated by measuring the Water contact angle (WCA). The obtained samples were also examined using infrared analysis (FT-IR), Scanning electron microscope (SEM), and Elemental analysis (SEM–EDS). All analyses were performed before and after the washing process in order to verify the stability of the performed modifications.
The crystal and molecular structures of two quarternary salts of 2-oxosparteine (II), the methiodide (IICH+3 • I−) and the methperchlorate (IICH+3 • ClO−4) have been determined on the basis of X-ray and IR data. The studies were performed by analogy to previously investigated quaternary salts of sparteine (I), the methiodide (ICH+3 • I−) and the methperchlorate (ICH+3 • ClO−4). As expected, the configurations and conformations of cationic parts within the two pairs of quaternary salts are identical, except for the structure of their A/B fragments, which in ICH+3 cations have the character of tertiary amines, but in IICH+3 that of lactams.
On the basis of accumulated X-ray and IR data the similarities and differences in the modes of interaction of perchlorate and iodide anions with quaternary cations, and especially with their N+---CH3 groups are discussed. In this discussion are also included the methiodide and methperchlorate of -isosparteine: IIICH+3 • X− (X− = I− or ClO−4) where N+---CH3 groups are cisoidally oriented to the basic nitrogen atoms. The most interesting observations are as follows: (i) When N+---CH3 groups are easily accessible for direct quasi hydrogen bonding interactions with counter anions and when other positive charged groups, for instance lactam groups, are absent in quaternary cations, perchlorate anions interact more strongly than the iodide anions and in consequence introduce conformational changes into the ring with N+---CH3 group as well as into further rings. (ii) Perchlorate and iodide anions interact with N+---CH3 groups similarly and very weakly if at all, when the N+---CH3 groups are for steric reasons inaccessible to counter anions or when in quaternary cations there are additional groups which attract the counter anions electrostatically. The last mechanism operates in both quaternary salts of 2-oxosparteine and this is the reason why their monocrystals are isosteric and IR spectra almost identical. (iii) The sterically hindered N+---CD3 groups in both IIICD+3 • X− salts give rise in their IR spectra to two doubles of sharp, well resolved bands which indicate the presence of two different rotamers stabilized by two modes of weak intramolecular hydrogen bonds with basic N atoms. (iv) In IIICH+3 • X− and IIICD+3 • X− salts the perchlorate and iodide anions do not interact at all with the rotating and vibrating N+---CH3 (N+---CD3) group but the structures of these salts are not isosteric since the perchlorate anions interact more strongly than iodide anions with the A/B fragment of the IIICH+3 cations. This is visible from the shapes and intensities of the so-called “trans” band in the IR spectra of both salts. 相似文献