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91.
Periodic, chaotic, chattering, and bifurcation behavior are fundamental consequences of the nonsmooth nature of systems with dry friction. This work is concerned with the analysis of a single degree of freedom system which is additionally damped by a delayed dry friction device. We get a complete set of closed-form expressions to describe the dynamics of the delay-induced phenomena exhibited by the system. The conditions to determine the existence and stability of limit cycles are clearly defined. This analysis is addressed in the context of both classic stability theory for nonlinear systems and the qualitative theory of Piecewise Smooth Dynamical Systems. Through exhaustive numerical simulations the effectiveness of the set of closed-form expressions is confirmed. Excellent agreement was found between the numerical and analytical results. 相似文献
92.
通过重氮盐方法合成含酞菁锰乙烯基咔唑单体,再经自由基共聚合,分别获得了具有光电导性能的含酞菁锰聚合物Ⅰ、Ⅱ、Ⅲ.讨论了采用IR、VV/Vis、元素分析、原子吸收等手段对单体和聚合物Ⅰ、Ⅱ、Ⅲ的结构表征,通过荧光光谱分析,初步探讨了它们的光电导机理 相似文献
93.
Wetting properties of a solid surface can change as a consequence of chemical treatment. There is a relationship between the molecular structure of a surface and the macroscopic properties of this surface such as wetting and adhesion. Information on the surface energy of a solid was obtained by calculating polar and dispersion force contributions by means of contact angle determination. The superficial modification undergone by human hair treatments with or without hydrogen peroxide at alkaline pH was studied by means of wetting force measurements. The wetting increase in treated human hair fibers was analyzed following the Hüttinger method using contact angle data, taking into account the acid-base and dispersion components of the total wetting adhesion work. The hydrogen peroxide treatment at alkaline pH leads to a partial removal of hydrocarbon chains and to the formation of ionic groups (cysteic acid residues) on the outer scale cell surface. The latter phenomenon was observed by means of an increase in the acid-base adhesion work versus water wetting liquid at alkaline pH. Copyright 2001 Academic Press. 相似文献
94.
Experimental Mechanics - Metaconcrete is a new concept of concrete, showing marked attenuation properties under impact and blast loading, where traditional aggregates are partially replaced by... 相似文献
95.
96.
Zaina Ibrahim Mohamed Allaoui Estelle le Gall Dr. Arnaud Fihey Rodrigo Plaza-Pedroche Dr. Claudine Katan Prof. Françoise Robin-le Guen Prof. Julián Rodríguez-López Dr. Sylvain Achelle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8153-8161
The photophysical properties of a series of conjugated push–pull (iso)quinolines were studied. The compounds were synthesized by well-established and straightforward methodologies. The materials exhibited not only emission solvatochromism in a variety of nonpolar solvents, but also tunable halochromism. Some of the compounds remained moderately luminescent after protonation and had a red emissive form, which was used to obtain white-light emission, both in solution and in thin films, by controlled protonation of the initially blue–green-emitting materials. This methodology has potential applications in the fabrication of white organic light-emitting diodes with two forms of a single emitter in equilibrium. 相似文献
97.
Guoliang Zhu Hui Zeng Shuangbo Zhang Jana Juli Xiaoyun Pang Jan Hoffmann Yan Zhang Nina Morgner Yun Zhu Guohong Peng Hartmut Michel Fei Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):351-359
Respiratory chain complexes convert energy by coupling electron flow to transmembrane proton translocation. Owing to a lack of atomic structures of cytochrome bc1 complex (Complex III) from thermophilic bacteria, little is known about the adaptations of this macromolecular machine to hyperthermophilic environments. In this study, we purified the cytochrome bc1 complex of Aquifex aeolicus, one of the most extreme thermophilic bacteria known, and determined its structure with and without an inhibitor at 3.3 Å resolution. Several residues unique for thermophilic bacteria were detected that provide additional stabilization for the structure. An extra transmembrane helix at the N-terminus of cyt. c1 was found to greatly enhance the interaction between cyt. b and cyt. c1, and to bind a phospholipid molecule to stabilize the complex in the membrane. These results provide the structural basis for the hyperstability of the cytochrome bc1 complex in an extreme thermal environment. 相似文献
98.
99.
Joan Ribas Josep M. Juliá Xavier Solans Manuel Font-Altaba Antonio Isalgué Xavier Tejada 《Transition Metal Chemistry》1984,9(2):57-62
Summary The two new title compounds have been synthesized and characterized by x-ray crystal structure and spectroscopic measurements. Both compounds are air-stable and isomorphous. The crystal system, space group and Z for both compounds are: hexagonal, p61 and 6. Lattice constants for the CoIII and CrIII complexes are as follows:a = 9.674(3) Å,c = 37.196(6) Å anda = 9.786(3) Å,c = 37.852(6) A, respectively. The molecular structure shows a great distortion in the Fe-C-N-M torsion angle [–46.8(7)° and –51.3(7)°, respectively] which has been interpreted as due to the presence of the NO ligand. The spectral studies confirm the presence of the -cyano ligand by the clear splitting of the (CN) stretching vibration atca. 2200 cm–1 and the shift of 15–20 nm towards higher frequencies in the first d-d transition of MIII. The13C-n.m.r. spectrum of the diamagnetic CoIII complex confirms the presence of the -cyano ligand in solution and, as in the solid phase, the bridging group iscis to the NO of the nitroprusside. The Mössbauer spectra show that the principal axis component of electric field gradient tensor will most likely be directed in the Fe-NO direction (as in the nitroprusside ion) and not towards the CN bridge. 相似文献
100.
Jianmin Jiao Dr. Guangping Sun Jikun Zhang Prof. Dr. Chen Lin Prof. Dr. Juli Jiang Prof. Dr. Leyong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(67):16601-16605
On the basis of cyclotrixylohydroquinoylene ( CTX ), a novel water-soluble phospholate-based CTX derivative ( WPCTX ) was prepared with facile synthetic procedure and satisfying yield. Several model guest molecules were selected to investigate WPCTX ′s host-guest properties. Based on the study of the host and model guest complexation, a tetraphenylethylene derivative from model guest was employed as a guest molecule ( G ) to form WPCTX⊃G nanoparticles (NPs) with WPCTX through further supramolecular self-assembly in water. Moreover, a hydrophobic fluorescent dye, Eosin Y( ESY ) or Nile red ( NiR ), was encapsulated in WPCTX⊃G NPs to construct two types of artificial light-harvesting systems. Their high antenna effect demonstrated such NPs successfully mimicked light-harvesting systems in nature. 相似文献