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781.
782.
Micelle to vesicle transitions of N-dodecyl-1, ω-diaminoalkanes: effects of pH, temperature and salt
The self-assembly behavior of pH-sensitive amphiphiles N-dodecyl-1, 2-diaminoethane (C12N2N), N-dodecyl-1, 3-diaminopropane (C12N3N) and N-dodecyl-1, 4-diaminobutane (C12N4N) has been studied in aqueous solutions. Light scattering, viscosity and cryo-transmission electronic microscopy (cryo-TEM) results revealed that the aggregates transferred from spherical micelles to vesicles (MVT) via wormlike micelles as the pH was gradually varied from acidic to basic conditions. pH-dependent zeta potential and (1)H NMR studies confirmed these transitions. Interestingly, the formed wormlike micelles could transform into vesicles upon heating, which was studied by cryo-TEM, light scattering and viscosity techniques in detail. It is concluded that the pH and thermal MVT are a general phenomenon in all three amphiphiles investigated. Furthermore, NaCl induced a wormlike micelle to vesicle transition was also observed in C12N2N solution. 相似文献
783.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
784.
Junjie Ye Xuefeng Chen Zhi Zhai Bing Li Yugang Duan Zhengjia He 《Mechanics of Composite Materials》2010,46(4):405-416
This paper aims to investigate the effect of microstructure parameters (such as the cross-sectional shape of fibers and fiber
volume fraction) on the stress–strain behavior of unidirectional composites subjected to off-axis loadings. A micromechanical
model with a periodic microstructure is used to analyze a representative volume element. The fiber is linearly elastic, but
the matrix is nonlinear. The Bodner–Partom model is used to characterize the nonlinear response of the fiber-reinforced composites.
The analytical results obtained show that the flow stress of composites with square fibers is higher than with circular or
elliptic ones. The difference in the elastoplastic response, which is affected by the fiber shape, can be disregarded if the
fiber volume fraction is smaller than 0.15. Furthermore, the effect of fiber shape on the stress–strain behavior of the composite
can be ignored if the off-axis loading angle is smaller than 30°. 相似文献
785.
A univariate Hawkes process is a simple point process that is self-exciting and has a clustering effect. The intensity of this point process is given by the sum of a baseline intensity and another term that depends on the entire past history of the point process. Hawkes processes have wide applications in finance, neuroscience, social networks, criminology, seismology, and many other fields. In this paper, we prove a functional central limit theorem for stationary Hawkes processes in the asymptotic regime where the baseline intensity is large. The limit is a non-Markovian Gaussian process with dependent increments. We use the resulting approximation to study an infinite-server queue with high-volume Hawkes traffic. We show that the queue length process can be approximated by a Gaussian process, for which we compute explicitly the covariance function and the steady-state distribution. We also extend our results to multivariate stationary Hawkes processes and establish limit theorems for infinite-server queues with multivariate Hawkes traffic. 相似文献
786.
Xiling Yu Youchen Liu Xuefeng Yu Yi SunShenhao ChenChao Wang 《Optics and Lasers in Engineering》1996,25(2-3)
This paper discusses some new optical measurement techniques for the study of crystal growth and electrode processes, namely, holographic phase-contrast interferometric microphotography (HPCIM), phase conjugation interferometry (PCI) and laser diffractometry. Using these techniques, real-time crystal growth and electrode processes can be observed; solid-liquid interface boundary layers and the crystal surface morphology can be studied quantitatively and solution saturation and crystal growth rates can be measured precisely. These techniques are also compared with other methods. 相似文献
787.
Bromochlorodifluoromethane(CF2BrCl),also knownasHalon1211inindustry,isamainagent widelyusedforfiresuppressionapplicationsandhas receivedconsiderableattentionbecauseofitspotential forstratosphericozonedepletion[1,2].Thedetailed informationonpropertiesofCF2BrClmoleculesuchas ionizationpotential,chemicalbondingcharacterand electrondensitydistributionofmolecularorbitals,especiallyofthefrontiermolecularorbitals,isbelieved tobeimportantforchemicalreactionandpossible molecularrecognitionaccordingt… 相似文献
788.
Laser diode interferometer used for measuring displacements in large range with a nanometer accuracy
In this paper, the displacement of an object is measured with a photothermal phase-modulating laser diode interferometer. A feedback control system is designed to reduce the measurement errors caused by the fluctuations in the optical wavelength of the laser diode and the vibrations of the optical components in the interferometer. A new method is proposed to enlarge the measuring range of displacement. Using this method, the measuring range is enlarged from half wavelength to nearly 125 μm and the measurement accuracy is about 1 nm. The simulation and experimental results have shown the usefulness of the method and the feedback control system. 相似文献
789.
Yang Xuefeng 《数学学报(英文版)》1993,9(4):401-405
In this paper, we use the deformation method andG-equivariant theory to prove the existence and multiplicity of harmonic maps from an annulus to the unit sphere inℝ
3 with symmetric boundary value. In particular, we can get infinitely many homotopically different harmonic maps if the boundary
value isS
1-equivariant and nonconstant.
This research partially supported by the NNSF, P.R. China. 相似文献
790.
验证相对论效应实验装置能够形象直观而又方便地验证快速电子的能量与动量的相对论关系.近年来的重新设计和改进在保留原有优点和特色的基础上改进了原装置的不足,突出了综合型、设计型的特点,真正达到了一机多用的目的,符合面向二十一世纪物理实验教学改革的趋势和方向. 相似文献