Displacement potentials for membranes in stretching and stress-function potentials for plates in bending

Summary This paper proposes to use Helmholtz's representation of displacement component for the formulation of flat plates in extension. This is an alternative formulation equivalent to the classical formulation using Airy's stress function. On the other hand, by means of Southwell's analogies, it is possible to introduce some new quantities called stress-function potentials which lead to an another alternative formulation of flat plates in flexure. Some simple examples for stretching and bending case illustrate the merits of the above mentioned formulation.

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Übersicht Zur Bestimmung des ebenen Spannungszustandes elastischer Medien wird die von Hehnholtz angegebene Darstellung verwendet, die eine Alternative zum üblichen Vorgehen unter Verwendung der Airyschen Spannungsfunktion bietet. Unter Verwendung der Southwellschen Analogie lassen sich als neue Größen die Potentiale der Spannungsfunktionen einführen, so daß eine Theorie der Plattenbiegung ähnlich wie die von Lagrange und Kirchhoff gewonnen wird. Das wird an einigen einfachen Beispielen erläutert.

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The author is grateful to Professor Ch. Massonet for his interest and encouregement during the course of this work.     

Partie finie d'un système dynamique et deux nouvelles démonstrations du théorème de Hopf

Sans résuméEquipe de Recherche n1 «Processus Stochastiques et applications» dépendant de la section n1 «Mathématiques, Informatique» associée au C.N.R.S.     

Delay model of glucose-insulin systems: Global stability and oscillated solutions conditional on delays

Recently P. Palumbo, S. Panunzi and A. De Gaetano analyzed a delay model of the glucose-insulin system. They proved its persistence, the existence of a unique positive equilibrium point, as well as the local stability of this point. In this paper we consider further the uniform persistence of such equilibrium solutions and their global stability. Using the omega limit set of a persistent solution and constructing a full time solution, we also investigate the effect of delays in connection with the behavior of oscillating solutions to the system. The model is shown to admit global stability under certain conditions of the parameters. It is also shown that the model admits slowly oscillating behavior, which demonstrates that the model is physiologically consistent and actually applicable to diabetological research.     

Multinuclear luminescent Schiff-base Zn-Nd sandwich complexes

Multinuclear 3d-4f complexes with sandwichlike molecular structures are formed with the Schiff-base ligand bis(3-methoxysalicylidene)ethylene-1,2-phenylenediamine(H(2)L). The stoichiometry and structures are dependent on the Zn:Nd ratio and counteranions present. They are trinuclear [Nd(ZnL)2(NO3)2(H2O)2].NO3.EtOH.H2O (1), [Nd(ZnL)2Cl2(H2O)3].Cl.2MeOH.5H2O (2), and tetranuclear [Nd2(ZnL)2Cl6(MeOH)2].MeOH (3). Dinuclear complex [NdZnL(NO3)3MeCN].MeCN (4) was also characterized. Near-infrared (NIR) lanthanide luminescence is observed in these complexes.     

Fast extraction, amplification and analysis of genes from human blood

In order to shorten the time spent on the sample preparation for gene analysis, a novel method was proposed through the combination of fast DNA extraction and purification by Generation capture disk, amplification by capillary polymerase chain reaction, and confirmation of amplification products by microchip electrophoresis. With this method, 3 microL blood was enough to obtain adequate target fragments in human genes. Under the optimal conditions in each step, the sample preparation for eight fragments in beta-globin gene and four fragments in ras gene could be finished within 20 min. Since all the experiments were performed on commercial instruments, this method showed a wide range of applicability. In addition, other advantages such as fast speed and low consumption of samples were demonstrated. All these merits proved that such a combination method was of great potential for the clinical diagnostics.     

Rapid analysis of oligosaccharides derived from glycoproteins by microchip electrophoresis

A novel method for fast profiling of complex oligosaccharides released from glycoproteins based on microchip electrophoresis (mu-CE) is presented here. The characterization of separation conditions, i.e., the composition, concentration and pH of running buffer as well as the applied voltage, has been performed using maltose (G2), cellobiose ( G2'), maltriose (G3) and panose (G3') as oligosaccharide isomer models. In mu-CE, much better separation of oligosaccharide isomers and oligosaccharide ladder was obtained in phosphate buffer than in borate buffer over a wide pH range. Under optimal conditions, high-performance separation of the N-linked complex oligosaccharides released from ribonuclease B, fetuin, alpha1-acid glycoprotein (AGP) and IgG was achieved using polymethylmethacrylate (PMMA) microchips with an effective separation channel of 30 mm. These results represent the first reported analysis of the N-linked oligosaccharides derived from glycoproteins by mu-CE, indicating that the present mu-CE-based method is a promising alternative for characterization of the N-linked oligosaccharides in glycoproteins.     

Primary study on the assay of superficial hydroxyl group content upon the solid polyvinyl alcohol

Polyvinyl alcohol is a multipurpose polymer, and there is abundant hydroxyl group on its surface. In this article, we first time attempted to assay the superficial hydroxyl group content on the solid polyvinyl alcohol (PVA-1799) with a degree of polymerization over 1700 and a degree of alcoholysis over 99.0%. The assay was carried out by two different titration systems. The results show: (1) the order of magnitude of superficial hydroxyl group content on its solid surface was about 3.8E-5 mol/cm2 by acylation system with single functional group reagent (acetic anhydride); while (2) the order of magnitude of superficial hydroxyl group content was about 1.4E-7 mol/cm2 by esterification system with bi-functional group reagent (Toluence 2,4-DiIsocyanate, TDI). The results would be useful to provide a quantitative reference when -OH on the solid PVA surface is intended to be utilized for surface modification for some application. Moreover, the results and their difference also offer us the knowledge of the surface modification efficiency.     

Ultrafast enzyme immobilization over large-pore nanoscale mesoporous silica particles

By finely tuning the TEOS/P123 molar ratio of the octane/water/P123/TEOS quadruple emulsion system and by controlling the synthesis conditions, an ultrafine emulsion system was isolated, under the confinement of which, nanoscale silica particles with ordered large mesopores (approximately 13 nm) have been successfully constructed; the obtained mesoporous silica particles have an unusual ultrafast enzyme adsorption speed and the amount of enzyme that can be immobilized is larger than that of conventional mesoporous silica, which has potential applications in the fast separation of biomolecules.     

Stereocontrolled synthesis of tricyclic fused oxazolidinone as antibacterial agent

Tricyclic fused oxazolidinone 3a and 3b have been synthesized as antibacterial agents in 12 and 11 steps respectively. The key intermediates 10a and 10b have been developed via opening of epoxide 9a and 9b and cyclization by the resulting oxygen anion attack.