Super-Kadomtsev—Petviashvili hierarchy and super-Grassmann manifold

The super-Kadomtsev-Petviashvili (SKP) hierarchy is introduced, and the general solutions are explicitly represented in terms of a superdeterminant. It is proved that the SKP hierarchy can be regarded as a dynamical system on a super-Grassmann manifold of infinite dimensions.     

Iron-Catalyzed Biomimetic Dimerization of Tryptophan-Containing Peptides

Biomimetic oxidative dimerization of tryptophan derivatives in aqueous media with oxygen as a bulk oxidant catalyzed by an iron octacarboxy phthalocyanine complex was established. The discovery of the extremely active iron catalyst enables aerobic enzyme-mimetic oxidation to be performed in a flask. This method was applicable to the oxidative dimerization of a wide range of tryptophan derivatives, including various dipeptides and oligopeptides, with remarkable functional-group tolerance without the protection of the amino acid residues. Furthermore, oxidative dimerization of tryptophan derivatives bearing dioxopiperazine units enabled the convergent total synthesis of five natural pyrroloindole compounds and unnatural congeners. The established chemical method provides facile access to a broad range of dimerized peptides with a unique scaffold to link two turn structures, which will serve as a powerful tool to create new small- and medium-sized-molecules as drug candidates.     

3-Oxo-4,4,4-trifluorobutyronitriles as building blocks of trifluoromethyl substituted heterocycles 2. Heterocyclization to 3-aryl-4-trifluoromethyl-2H-1-benzopyran-2-ones under hoesch reaction conditions

Resorcinol and 5-methylresorcinol, respectively, react with 3-oxo-2-aryl-4,4,4-trifluorobutyronitrile using zinc chloride as a catalyst in dibutyl ether under the Hoesch reaction conditions to give a low yield of 3-aryl-7-hydoxy-4-trifluoromethyl- or 3-aryl-5-hydroxy-7-methyl-4-trifluoromethyl-2H-l-benzopyran-2-ones. However, the related reaction with m-methoxyphenol was found to produce poor yields of 3-aryl-7-methoxy-4-trifluoromethyl-2H-1-benzopyran-2-one and its 3,4-dihydro-4-hydroxy derivative.     

Spatial mode compensation technique using progressive phase conjugation

Optical Review - We propose a spatial mode compensation method using progressive phase conjugation (PPC) to establish a dynamic control technology for mode distribution in multi-mode fiber (MMF)....     

An incremental theory of large strain and large displacement problems and its finite element formulation

Summary This paper is concerned with the development of an incremental finite'element theory for the large strain and the large displacement problems, referred to the current configuration of the body. Using the convected coordinate system which is embedded in the body, the incremental representations of strain and stress tensors and the energy relations are presented, and then the general procedure to construct the so-called element stiffness matrix in incremental form is considered. The finite element formulation is developed for a typical constitutive relation and it is shown that some correction matrices, some of which have been omitted in the previous works, are to be added to the element stiffness matrix. Finally the method to assemble the equations of the element to the global system is discussed and a simple finite element model satisfying the compatibility condition is presented.The finite element theory developed in this paper is able to be extended to the problems for the general thermodynamical process of a broad class of nonlinear materials.

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Übersicht Mit Hilfe der Methode der finiten Elemente wird eineZuwachstheorie zurBehandlung von Problemen mit endlicher Verformung abgeleitet. Dabei wird ein im Körper eingebettetes, der momentanen Form angepaßtes Bezugssystem verwendet. Es werden Ausdrücke für die Energie sowie für die Änderungen der Spannungs- und Verformungs-Tensoren abgeleitet und es wird ein Verfahren zur Konstruktion der Steifigkeitsmatrix für ein Element angegeben. Ein typisches Stoffgesetz wird dabei zugrundegelegt. Dabei zeigt es sich, daß einige in früheren Arbeiten vernachlässigte Korrektur-Matrizen zu der Steifigkeits-Matrix des Elementes hinzugefügt werden müssen. Die Möglichkeiten der Zusammenfassung der für die Elemente geltenden Gleichungen zu einem globalen Gleichungssystem werden diskutiert und es wird ein den Verträglichkeitsbedingungen genügendes Elemente-Modell angegeben.Das angegebene Verfahren kann für allgemeine thermodynamische Prozesse in einer breiten Klasse nichtlinearer Materialien erweitert werden.

     

Microbubble formations in MEMS-fabricated rectangular channels: A high-speed observation

A microfluidic device that consists of MEMS-fabricated rectangular channels is developed for stable and sequential production of monodispersed microbubbles. The central inlet for gas phase is located between two inlets for liquid phases, where the device works as a two-fluid atomizer. The interfacial flow mechanism of microbubble formation at the junction of the inlets in the device is investigated using a high-speed visualization technique and digital image processing. The periodic formation process is successfully realized by the consideration of the wettability between the microbubble and the channel wall. The produced microbubbles are relatively uniform in size, and the size is controlled from 113 to 153 μm by changing the flow rates of the liquid and gas phases. Furthermore, a simple theoretical model to predict the equivalent diameter of microbubbles is developed by considering the mass balance of the gas phase in the formation process, where the experimental and theoretical results are in reasonable agreement.     

Low-velocity pneumatic conveying in horizontal pipe for coarse particles and fine powders

First, the characteristics of low-velocity conveying of particles having different hardness are experimentally investigated in a horizontal pipeline in terms of flow pattern and pressure drop to show that the slug flow can be classified into two types depending on the settling of particles along the pipeline, and the period is small for slug flow without the settled layer, which is called solitary slug flow. The pressure drop for soft particles is shown to be larger than that for hard particles. Then, experimental results are presented on horizontal fluidized-bed conveying of fine powders to show that air release from the top surface of the conveying channel is an imnortant factor for high mass flow rate of particles.     

Analysis of repeated impacts on a steel rod with visco-plastic material behavior

In machine dynamics impacts are usually common phenomena, resulting from collisions of moving bodies. Even low velocity impacts might produce high stresses in the contact region, which result in inelastic deformation. Thereby, visco-plastic materials, such as steel, show a significant increase of the yield stress with the strain rate. In machine dynamics repeated collisions occur, resulting in repeated impacts on a previously deformed contact area. Then, inelastic deformation and the resulting residual stresses produced by previous impacts have an influence on the behavior of the following impacts. Thus, the impact behavior varies with the number of impacts. This paper presents a numerical and experimental evaluation of repeated impacts with identical impact velocity up to 3 m/s, whereby the deformation history of the contact area, due to previous impacts, is included. The approach is applied to longitudinal impacts of an elastic steel sphere on a steel rod with distinct visco-plastic material behavior which is identified by Split Hopkinson Pressure Bar tests. A Finite Element analysis and experimental verification using two Laser-Doppler-Vibrometers are performed. It is shown that for an accurate impact simulation the FE model must include the visco-plastic material behavior of the steel. Further it is found that the maximal contact force, the rebound velocity and the coefficient of restitution increase with the number of impacts, while the contact duration decreases with the number of impacts. After several impacts these quantities show saturation to a constant value, indicating no significant additional inelastic deformation in the later impacts. Further, the residual stress distribution, the maximal von Mises stress distribution and the local deformation at the contact point are evaluated and a characteristic force-deformation diagram is obtained. Finally, an analysis is performed to describe the relation between maximal force and remaining crater at the contact point.