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61.
J Emile MH Werts F Artzner F Casanova O Emile JR Navarro F Meneau 《Journal of colloid and interface science》2012,383(1):124-129
Dry aqueous foams made of anionic surfactant (SDS) and spherical gold nanoparticles are studied by small angle X-ray scattering and by optical techniques. To obtain stable foams, the surfactant concentration is well above the critical micelle concentration. The specular reflectivity signal obtained on a very thin film (thickness 20 nm) shows that functionalized nanoparticles (17 nm typical size) are trapped within the film in the form of a single monolayer. In order to isolate the film behavior, investigations are made on a single film confined in a tube. The film thinning according to the ratio of functionalized nanoparticle and SDS micelles (1:1, 1:10, 1:100) is mainly governed by the structural arrangement of SDS micelles. In thick films, nanoparticles tend to form aggregates that disappear during drainage. In particular self-organization of nanoparticles (with different surface charge) inside the film is not detected. 相似文献
62.
Florian Modicom Ellen M. G. Jamieson Elise Rochette Stephen M. Goldup 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3915-3919
We report the unexpected discovery of a tandem active template CuAAC‐rearrangement process, in which N2 is extruded on the way to the 1,2,3‐triazole product to give instead acrylamide rotaxanes. Mechanistic investigations suggest this process is dictated by the mechanical bond, which stabilizes the CuI‐triazolide intermediate of the CuAAC reaction and diverts it down the rearrangement pathway; when no mechanical bond is formed, the CuAAC product is isolated. 相似文献
63.
A high-performance liquid chromatography (HPLC) method was established using an analytical reversed-phase column and gradient
elution to achieve chromatographic separation of typical compounds in essential oils. For detection, a diode array detector
monitoring different wavelengths simultaneously as well as a mass spectrometer (MS) were used. Atmospheric pressure chemical
ionization operating in the positive mode turned out to be a suitable tool to detect volatiles of different chemical classes
and to identify them in essential oil matrices. Characteristic fingerprints of eucalyptus, lavender, may chang, pine, rosemary,
thyme, and turpentine essential oils monitored at a representative wavelength (220 nm) demonstrated the suitability of HPLC
in essential oil analysis. Additional monitoring wavelengths (210, 250, and 280 nm) provided useful information about the
identity of the specific component and opened the possibility to differentiate presumably coeluting compounds by means of
their distinct absorption behavior. Finally, peak assignment in seven essential oils was performed on the basis of characteristic
retention times and UV and MS data of a broad set of reference volatiles. 相似文献
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Florian Maire Catherine M. Lange 《Rapid communications in mass spectrometry : RCM》2010,24(7):995-1000
We report the formation of unexpected ions during the analyses of a first‐generation polyamidoamine dendrimer in negative ion mode using an ion trap equipped with an electrospray ionisation source. These surprising ions corresponded to an increase of 12 m/z units over those expected. The formation of the unexpected ions was dependent on the tuning of the solution flow rate and the capillary high voltage. In addition, measurements of unusual value of the current suggested that a reaction was occurring in the corona plasma. The influence of methanol in this phenomenon was demonstrated by using CD3OH in the sample preparation. We propose two structures to explain the observed adduct based on the results of MS2 experiments and by referring to previous work dealing with 12 m/z units addition. We showed that a corona discharge caused by alterations taking place to the electrospray capillary emitter was the origin of these unexpected ions. Finally, we discuss the mechanism involved in the formation of the ions and we propose means to control such artefacts. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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The problem analyzed is the classical non-regularized Hamiltonian formulation of a restricted three body problem under the influence of Coulomb-interactions. Completing the large literature on Helium-like systems we will consider the motions around a fixed positive point charge of (i) one negative and one positive point charge as well as the “classical” issue of (ii) two negative point charges. Thereby, all our considerations deal with arbitrary positive and negative charge values of the mass particles. Here, we give necessary and sufficient conditions for the existence of genuine equilibria in such systems—recall that there are none in the usual classical Helium-atom—and analyze their linearized stability. The thus obtained insights allow us to study the dynamics near such genuine equilibria. 相似文献
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