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371.
Meister A Weygand MJ Brezesinski G Kerth A Drescher S Dobner B Blume A 《Langmuir : the ACS journal of surfaces and colloids》2007,23(11):6063-6069
Infrared reflection absorption spectroscopy and X-ray reflectivity have been used to elucidate the molecular orientation and hydrocarbon chain conformation and packing of the symmetric long-chain bolaamphiphiles dotriacontane-1,1'-diyl-bis-[2-(trimethylammonio)ethylphosphate] (PC-C32-PC) and dotriacontane-1,1'-diyl-bis-[2-(dimethylammonio)ethylphosphate] (Me2PE-C32-Me2PE) at the air-water interface. At low surface pressures, these bipolar amphiphiles are found to lie flat on the water surface with a disordered chain. With increasing surface pressure, the alkyl chain becomes more ordered. Concomitantly, the chain is bent pointing into the air, whereas both polar headgroups keep contact with the water subphase. At an area of 0.9-1.1 nm2 per molecule, a surface pressure plateau is reached for both bolaamphiphiles, where the molecules adopt a reverse U-shaped conformation with a strongly tilted alkyl chain. Further compression leads to the formation of 3-D aggregates. 相似文献
372.
373.
Ga?l Raoul 《Monatshefte für Mathematik》2012,240(2):117-144
In this paper, we are interested in the nonlinear stability of Dirac-type steady solutions to an integro-differential equation appearing in the study of populations which are structured with respect to a quantitative (continuous) trait. We show that stability conditions of Adaptive Dynamics extend to this model. 相似文献
374.
375.
The ultrasonic vibration potentials and apparent molal volumes for many inorganic and organic electrolytes were measured in acetonitrile at 25°C and combined to obtain ionic contributions to the standard partial molal volumes V°(ion). Monatomic cations and anions of the same size essentially have the same V°(ion). Their size dependence can be interpreted through Hepler's equation. The apparent molal heat capacities were also measured in acetonitrile and used to derive standard values. Various methods of estimating C
p
0
(ion) were investigated and an ionic scale is proposed. It is concluded that C
p
0
(ion) of large organic ions are very close to the intrinsic heat capacities of the ions, and the solvation contribution to monatomic ions is positive for both cations and anions. 相似文献