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101.
Alfio?BorzìEmail author Georg?Propst 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2003,54(6):1050-1072
The Liebau phenomenon is the occurrence of valveless
pumping through the application of a periodic force at a place
which lies asymmetric with respect to system configuration. This
paper is concerned with two different physical configurations and
respective models. Comparison and derivation among the models is
discussed. Accurate numerical schemes which solve these models are
presented. By means of numerical simulations it is investigated
under which conditions valveless pumping takes place. 相似文献
102.
The thermodynamic parameters for the chelation of cupric ion with 2,2′-dipyridyl have been redetermined at 25°C and I=0.1 M. ΔG values were obtained by potentiometry with a selective ion electrode and ΔH values by direct calorimetry. Similar studies have been made on the relative hydroxocomplexes. The data obtained are compared with those in the literature and the chelate effect of the heterocyclic diimine is described. 相似文献
103.
104.
Tancredi T Carrà G Guerrini R Arduin M Calò G Regoli D Salvadori S Temussi PA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(7):2061-2070
Nociceptin is a heptadecapeptide whose sequence is similar to that of Dynorphin A, sharing a message domain characterized by two glycines and two aromatic residues, and a highly basic C-terminal address domain but, in spite of these similarities, displays no opioid activity. Establishing the relative importance of the message and address domains of nociceptin has so far been hampered by its extreme conformational flexibility. Here we show that mutants of this peptide, designed to increase the helical content in the address domain, can be employed to explain the mode of interaction with the NOP receptor. Nociceptin analogues in which Ala residues are substituted with aminoisobutyric acid (Aib) show a substantial increment of activity in their interaction with the NOP receptor. The increment of biological activity was attributed to the well-documented ability of Aib to induce helicity. Here we have verified this working hypothesis by a conformational investigation extended to new analogues in which the role of Aib is taken up by Leu. The NMR conformational analysis confirms that all Ala/Aib peptides as well as [Leu(7,11)]-N/OFQ-amide and [Leu(11,15)]-N/OFQ-amide mutants (N/OFQ=nociceptin/orphanin FQ) have comparable helix content in helix-promoting media. We show that the helical address domain of nociceptin can place key basic residues at an optimal distance from complementary acidic groups of the EL(2) loop of the receptor. Our structural data are used to rationalize pharmacological data which show that although [Leu(11,15)]-N/OFQ-amide has an activity comparable to those of Ala/Aib peptides, [Leu(7,11)]-N/OFQ-amide is less active than N/OFQ-amide. We hypothesize that bulky residues cannot be hosted in or near the hinge region (Thr(5)-Gly(6)-Ala(7)) without severe steric clash with the receptor. This hypothesis is also consistent with previous data on this hinge region obtained by systematic substitution of Thr, Gly, and Ala with Pro. 相似文献
105.
This paper deals with a recently observed effect of laser light on the growth of thin films on a CdS substrate deposited on glass. The possible origins of the phenomenon are analyzed and the experimental apparatus used to observe it is described. 相似文献
106.
Vincenzo Calò Prof. Angelo Nacci Prof. Antonio Monopoli Dr. Pietro Cotugno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(5):1272-1279
An efficient Ullmann-type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd-catalysed dehydrogenation of carbonyl compounds. 相似文献
107.
Benedetto Calò 《Annali di Matematica Pura ed Applicata》1893,21(1):195-220
108.
The purpose of the work is the realization of a composite material with long glass fibers having better characteristic than
a fiber random composite, to permit the reduction of weight and costs to shipyards for pleasure craft. Structural optimization
is performed by ANSYS for the choice of the layers disposition to obtain the maximum stiffness with minimum material employment,
saving weight. The study is centered on the research of the better configurations of plies packing in relation of pure shear
stress for four different plies. Unidirectional plies, both symmetric orthotropic and symmetric non-orthotropic ones, are
realized successively by the vacuum bag technique. Experimental tests of traction, bending, inter laminar shear and pure shear
are executed to characterize the three different type of material. Experimental results are compared to ones obtained numerically
to validate the procedures; the comparison with the analytical results permitted to attribute an adequate value to shape factor
of the fibers. In all the cases the optimization permitted the construction of much more resistant plies than random ones,
with a lower thickness. 相似文献
109.
110.
Bohmian mechanics is a quantum theory with a clear ontology. To make clear what we mean by this, we shall proceed by recalling first what are the problems of quantum mechanics. We shall then briefly sketch the basics of Bohmian mechanics and indicate how Bohmian mechanics solves these problems and clarifies the status and the role of the quantum formalism. 相似文献