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71.
Georgakilas V Gournis D Bourlinos AB Karakassides MA Petridis D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3904-3908
A new approach for the synthesis of amide macrocycles, based on the use of organo-clay derivatives as controlling template, is proposed as an alternative to the rotaxane method. Dications of p-xylylene diamine inserted in the clay interlayer space act as molding pillars around which neutral diamine molecules are erected via hydrogen bonding and pi-pi interactions to form supramolecular arrays. Condensation of diamines in the supramolecular arrays with diacetyl dichlorides yields various tetramide macrocycles in good yields. Shape, aromaticity and dimensions of the reactants are factors affecting the condensation reaction. 相似文献
72.
Vassiliki Papadimitriou Aristotelis Xenakis Athanasios E. Evangelopoulos 《Colloids and surfaces. B, Biointerfaces》1993,1(5)
The catalytic behaviors of α-chymotrypsin and of trypsin were studied in anionic AOT-isooctane-water and cationic CTAB-ROH-isooctane-water microemulsion systems. The effects of various parameters, such as the pH and the water content expressed in terms of the molar ratio wo = [H2O]/[Surfactant], on the enzyme activity, were examined. The kinetic constants were calculated and it was found that in the case of trypsin the enzyme exhibited a remarkable “superactivityrd, when studied in the CTAB microemulsion systems. The effect of the alcohol cosurfactant used in these cationic systems was investigated in relation to the polarity of the reaction medium. By using the hydrophilic probe 1-methyl-8-oxyquinolinium betaine the micropolarity of the water core was determined and related to the kinetic results. 相似文献
73.
A new bilevel formulation for the vehicle routing problem and a solution method using a genetic algorithm 总被引:2,自引:0,他引:2
Yannis Marinakis Athanasios Migdalas Panos M. Pardalos 《Journal of Global Optimization》2007,38(4):555-580
The Vehicle Routing Problem (VRP) is one of the most well studied problems in operations research, both in real life problems
and for scientific research purposes. During the last 50 years a number of different formulations have been proposed, together
with an even greater number of algorithms for the solution of the problem. In this paper, the VRP is formulated as a problem
of two decision levels. In the first level, the decision maker assigns customers to the vehicles checking the feasibility
of the constructed routes (vehicle capacity constraints) and without taking into account the sequence by which the vehicles
will visit the customers. In the second level, the decision maker finds the optimal routes of these assignments. The decision
maker of the first level, once the cost of each routing has been calculated in the second level, estimates which assignment
is the better one to choose. Based on this formulation, a bilevel genetic algorithm is proposed. In the first level of the proposed algorithm, a genetic algorithm is used for calculating the population of the most promising assignments of
customers to vehicles. In the second level of the proposed algorithm, a Traveling Salesman Problem (TSP) is solved, independently for each member of the population
and for each assignment to vehicles. The algorithm was tested on two sets of benchmark instances and gave very satisfactory
results. In both sets of instances the average quality is less than 1%. More specifically in the set with the 14 classic instances
proposed by Christofides, the quality is 0.479% and in the second set with the 20 large scale vehicle routing problems, the
quality is 0.826%. The algorithm is ranked in the tenth place among the 36 most known and effective algorithms in the literature
for the first set of instances and in the sixth place among the 16 algorithms for the second set of instances. The computational
time of the algorithm is decreased significantly compared to other heuristic and metaheuristic algorithms due to the fact
that the Expanding Neighborhood Search Strategy is used. 相似文献
74.
A global optimization approach for the linear two-level program 总被引:4,自引:0,他引:4
Linear two-level programming deals with optimization problems in which the constraint region is implicity determined by another optimization problem. Mathematical programs of this type arise in connection with policy problems to which the Stackelberg leader-follower game is applicable. In this paper, the linear two-level programming problem is restated as a global optimization problem and a new solution method based on this approach is developed. The most important feature of this new method is that it attempts to take full advantage of the structure in the constraints using some recent global optimization techniques. A small example is solved in order to illustrate the approach.The paper was completed while this author was visiting the Department of Mathematics of Linköping University. 相似文献
75.
Mathias Rech Athanasios Batagiannis Jürg Hulliger 《Journal of mathematical chemistry》2009,46(4):1181-1187
Vector property generation is discussed for chain growth by higher order interactions. Because of a deterministic property
evolution a state space approach was used. Although not strictly Markovian, the system shows ergodic properties and convergence
for a large number of attachment steps. For reasonable interaction energies attributed to increasing order, the main extra
contribution to polarity formation results from interactions up to next nearest neighbours. Nonlinear equations up to third
order were solved by an iterative procedure. 相似文献
76.
Zusammenfassung Zur anorganischen Multielementanalyse ist die Gas-Chromatographie von Diäthyldithiocarbamaten geeignet. Mit einem FID können bereits Kationen im 0,6–0,06 ppm-Bereich nach Ausschütteln der wäßrigen Lösungen bestimmt werden. Di(trifluoräthyl)dithiocarbamate zeigen noch höhere Flüchtigkeiten. Eigenschaften und gas-chromatographisches Verhalten einiger dieser Chelate werden angegeben.Die Untersuchungen wurden in dankenswerter Weise durch Sachmittel der Deutschen Forschungsgemeinschaft und des Verbands der Chemischen Industrie unterstützt. Für die Gewährung eines Promotionsstipendiums sei der Friedrich-Ebert-Stiftung ebenfalls gedankt. 相似文献
77.
Bourlinos AB Raman K Herrera R Zhang Q Archer LA Giannelis EP 《Journal of the American Chemical Society》2004,126(47):15358-15359
Surface functionalization of the solid heteropolyacid H3PW12O40 with a bulky PEG-containing quaternary ammonium cation through partial proton exchange leads to a polyoxometalate-based liquid salt with high-temperature proton conductivity ( approximately 10-3 S cm-1 at 140 degrees C) under dry conditions. The proton conductivity of the liquid salt is 4 orders of magnitude higher than that of the solid analogue under identical conditions and shows super ionic behavior as defined by Walden plot. 相似文献
78.
Li X Kevrekidis IG Pollmann M Papathanasiou AG Rotermund HH 《Chaos (Woodbury, N.Y.)》2002,12(1):190-203
We first briefly review the subject of spatiotemporal pattern formation on microdesigned composite catalysts. One of the most significant interaction mechanisms between different reacting domains (consisting of different metal catalysts such as Pt and Rh, coupled through surface diffusion) is the initiation of reaction fronts at the interface between them. We then explore in some detail the effect of two-dimensional composite geometry on this basic building block of composite catalyst dynamics. (c) 2002 American Institute of Physics. 相似文献
79.
Sophia Demoulini David M. A. Stuart Athanasios E. Tzavaras 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2000,17(6):711
It is shown that the variational approximation scheme for one-dimensional elastodynamics given by time discretisation converges, subsequentially, weakly and a.e. to a weak solution which satisfies the entropy inequalities. We also prove convergence under the restriction of positive spatial derivative (for longitudinal motions). 相似文献
80.
Aristeidis Ntoukas Athanasios Niarchos Aikaterini C. Tsika Spiridon Mantzoukas Georgios A. Spyroulias Konstantinos Poulas 《Electrophoresis》2021,42(6):786-792
Numerous molecular biological experiments performed throughout the world require the detection or quantification of a protein of interest. Western blotting is one of the most popular techniques used for this purpose and offers quantitative information with the aid of specialized software. However, its dependence on the picture that is captured, and the background and the absence of a common protocol prevent the technique from being completely quantitative. To overcome these obstacles, we present a simple and reliable assay that is similar to the regular technique, with the exception of the last stage of band visualization and quantification. We propose that small pieces of the blot that include the protein of interest can be cut and dipped in a small volume of 3,3',5,5'-tetramethylbenzidine solution, giving a colorimetric signal with linear dependence on the quantity of the protein. The reaction is stopped with H2SO4, and the signal is measured in a plate reader. This modification shows high linearity without additional costs and can be applied for both purified proteins and proteins found in a lysate. The results obtained with our proposed technique were compared with those obtained by the conventional method and proved to be more reliable. 相似文献