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101.
R. Todorov R. Cohen D. Exerowa 《Colloids and surfaces. A, Physicochemical and engineering aspects》2007,310(1-3):32-38
Surface properties of foam films formed from aqueous dispersions of dipalmitoyl-phosphatidylcholine (DPPC) and from solutions of a phospholipid fraction of lung surfactant (TPL) are studied employing the foam film method. Experiments are carried out within a wide range of NaCl concentrations (Cel) and the ranges of Cel determining formation of common films (CF), common black films (CBF) and bilayer Newton black films (NBF) are found. The thickness (h) of the CF and CBF decreases with the increase of Cel until the critical electrolyte concentrations (Cel, cr) is reached. The determined Cel, cr that characterize the transition to NBF show that Cel, cr of the TPL films is an order of magnitude higher than that of the DPPC films. The measured h of the TPL films is higher than that of the DPPC films in the whole Cel range. Besides, only the h(Cel) curve of the DPPC films outlines a metastable Cel range where both CF and NBF are obtained. Both the h(Cel) curves and the direct measurements of the disjoining pressure isotherms of the DPPC films (Π(h) isotherms) demonstrate the role of electrostatic repulsive forces for the stability of the phospholipid films The obtained results are compared with the DLVO theory equations and the evaluated potentials of the diffuse electric layer φ0 20 mV for the DPPC films and φ0 100 mV for TPL films show the strong effect of the charged phospholipids in the TPL mixture on the electric properties at the film interfaces. 相似文献
102.
B. B. Ivanova M. G. Arnaudov St. Todorov W. S. Sheldrick H. Mayer-Figge 《Structural chemistry》2006,17(1):49-56
As part of an investigation on the coordination ability of peptides, structural analyses of the solid tripeptide glycyl-methionyl-glycine (H-Gly-Met-Gly-OH) and its hydrochloride have been carried out. The quantum chemical calculations (B3LYP/6-31+G(d) and UHF/6-31G**) and linear-dichroic infrared (IR-LD) spectroscopy predict a near to linear structure of the pure ligand, but the experimental IR-LD data are in accordance with a cross-linked disposition of both amide fragments in the protonated form. This result is confirmed by an X-ray diffraction study of latter compound. The presented work also demonstrates the possibilities of IR-LD spectral analysis for the structural characterization of an amorphous system such as the investigated tripeptide. 相似文献
103.
In this paper we introduce the concept of solving strategy for a linear semi-infinite programming problem, whose index set is arbitrary and whose coefficient functions have no special property at all. In particular, we consider two strategies which either approximately solve or exactly solve the approximating problems, respectively. Our principal aim is to establish a global framework to cope with different concepts of well-posedness spread out in the literature. Any concept of well-posedness should entail different properties of these strategies, even in the case that we are not assuming the boundedness of the optimal set. In the paper we consider three desirable properties, leading to an exhaustive study of them in relation to both strategies. The more significant results are summarized in a table, which allows us to show the double goal of the paper. On the one hand, we characterize the main features of each strategy, in terms of certain stability properties (lower and upper semicontinuity) of the feasible set mapping, optimal value function and optimal set mapping. On the other hand, and associated with some cells of the table, we recognize different notions of Hadamard well-posedness. We also provide an application to the analysis of the Hadamard well-posedness for a linear semi-infinite formulation of the Lagrangian dual of a nonlinear programming problem. 相似文献
104.
M. A. Goberna M. A. Lopez M. Todorov 《Journal of Optimization Theory and Applications》1995,86(1):37-56
This paper deals with the conditions for the uniqueness of the optimal solution of an optimization problem for which the objective function is linear and the feasible set is a closed convex set in a finite-dimensional space. Some of these conditions, such as strong unicity andw-unicity (a new transition concept), involve only the feasible set. Others are related to the properties of the chosen linear representation. To some extent, the paper surveys the literature about unicity and strong unicity in linear semi-infinite programming.This work was partially supported by the DGICYT of Spain, Grant PS90-0158, by the Bulgarian Ministry of Education and Science, Grant MM-408/94, and by the EC Commission, Grant CIPA-3510PL929132. 相似文献
105.
106.
Bojko Bakalov Nikolay M. Nikolov Karl-Henning Rehren Ivan Todorov 《Communications in Mathematical Physics》2007,271(1):223-246
The superselection sectors of two classes of scalar bilocal quantum fields in D ≥ 4 dimensions are explicitly determined by working out the constraints imposed by unitarity. The resulting classification
in terms of the dual of the respective gauge groups U(N) and O(N) confirms the expectations based on general results obtained in the framework of local nets in algebraic quantum field theory,
but the approach using standard Lie algebra methods rather than abstract duality theory is complementary. The result indicates
that one does not lose interesting models if one postulates the absence of scalar fields of dimension D−2 in models with global conformal invariance. Another remarkable outcome is the observation that, with an appropriate choice
of the Hamiltonian, a Lie algebra embedded into the associative algebra of observables completely fixes the representation
theory. 相似文献
107.
Martinez-Ponce G Petrova T Tomova N Dragostinova V Todorov T Nikolova L 《Optics letters》2004,29(9):1001-1003
We present a holographic lens with novel features recorded in an azopolymer film. Two holographic modulations, bulk birefringence and surface relief, are induced in the medium at the same time. The resultant holographic element has two focal planes, and the polarization of light in the focal points depends on the polarization of the incident light. Applications of this device for writing-reading information in two planes simultaneously or separately are described. 相似文献
108.
We describe a method to create ligands specific for a given protein family. The method is applied to generate ligand candidates for the cyclin-dependent kinase (CDK) family. The CDK family of proteins is involved in regulating the cell cycle by alternately activating and deactivating the cell's progression through the cycle. CDKs are activated by association with cyclin and are inhibited by complexation with small molecules. X-ray crystal structures are available for three of the thirteen known CDK family members: CDK2, CDK5 and CDK 6. In this work, we use novel computational approaches to design ligand candidates that are potentially inhibitory across the three CDK family members as well as more specific molecules which can potentially inhibit one or any combination of two of the three CDK family members. We define a new scoring term, SpecScore, to quantify the potential inhibitory power of the generated structures. According to a search of the World Drug Alerts, the highest scoring SpecScore molecule that is specific for the three CDK family members shows very similar chemical characteristics and functional groups to numerous molecules known to deactivate several members of the CDK family. 相似文献
109.
Spectral and kinetic investigations of the reversible photoinduced dichroism in KCl : Na containing FA and FA + FB centers are done. It is suggested that in presence of FB centers the observed 〈100〉 and 〈110〉 dichroism is connected with the FB(II) centers. 相似文献
110.