Development of an experimental system for a snake-like gliding model

A snake, which has a simple shape without limbs, can move over rough terrain, climb a wall or tree, swim, and glide through the air. It is difficult to understand the gliding flight of a snake in aerodynamics assuming a static model, because a snake undulates its body trunk and turns in air. This paper presents an experimental system for investigation of the relationship between the shape of the gliding snake model and gliding characteristics. Results of a gliding experiment confirm a sufficiently high reproducibility of the experiment.     

Novel non-peptide fibrinogen receptor antagonists. 1. Synthesis and glycoprotein IIb-IIIa antagonistic activities of 1,3,4-trisubstituted 2-oxopiperazine derivatives incorporating side-chain functions of the RGDF peptide

Based on the lead tetrapeptide RGDF, two possible non-peptide glycoprotein (GP) IIb-IIIa antagonists possessing an (S)-2-oxopiperazine-3-acetic acid moiety as a scaffold incorporating the indispensable Asp fragment were prepared, and (S)-4-[[trans-[4-(guanidinomethyl)-cyclohexyl]carbonyl]glycyl]-2- oxopiperazine-1,3-diacetic acid, 1a, was identified as a potential lead. A series of 3-substituted 2-oxopiperazine-1-acetic acids bearing the Arg-Gly equivalent at the 4-position were prepared and evaluated for their ability to prevent platelet aggregation and for their binding affinity for the GP IIb-IIIa receptor purified from human HEL cells. (S)-4-[(4-Amidinobenzoyl)glycyl]-3-[(methoxycarbonyl)methyl]- 2-oxopiperazine-1-acetic acid, 9 (TAK-029), inhibited in vitro human platelet aggregation with an IC50 value of 0.03 microM and GP IIb-IIIa-fibrinogen binding with an IC50 value of 0.49 nM. The [4-(2-aminoethyl)benzoyl]glycyl derivative 26 showed activity comparable to that of 9 (IC50 = 0.093 microM, guinea pig platelet aggregation assay). Compound 9 dose-dependently inhibited ex vivo platelet aggregation in guinea pigs (0.03 and 0.1 mg/kg, i.v.), and long-lasting inhibition of platelet aggregation was observed upon oral administration of 9 (3 mg/kg) to guinea pigs. On the other hand, the activity of 26 disappeared within 1 h after a dose of 1 mg/kg (i.v.). Compound 9 may therefore be useful in the clinical treatment of arterial thrombotic diseases.     

A suppressor mutation which suppresses adenylyl cyclase mutations in Neurospora crassa

Membranous obstruction of the inferior vena cava at the suprahepatic level is rare. The present report summarizes direct operative repair. A review of alternative therapeutic strategies is presented.     

Parallel computing of high‐speed compressible flows using a node‐based finite‐element method

An efficient parallel computing method for high‐speed compressible flows is presented. The numerical analysis of flows with shocks requires very fine computational grids and grid generation requires a great deal of time. In the proposed method, all computational procedures, from the mesh generation to the solution of a system of equations, can be performed seamlessly in parallel in terms of nodes. Local finite‐element mesh is generated robustly around each node, even for severe boundary shapes such as cracks. The algorithm and the data structure of finite‐element calculation are based on nodes, and parallel computing is realized by dividing a system of equations by the row of the global coefficient matrix. The inter‐processor communication is minimized by renumbering the nodal identification number using ParMETIS. The numerical scheme for high‐speed compressible flows is based on the two‐step Taylor–Galerkin method. The proposed method is implemented on distributed memory systems, such as an Alpha PC cluster, and a parallel supercomputer, Hitachi SR8000. The performance of the method is illustrated by the computation of supersonic flows over a forward facing step. The numerical examples show that crisp shocks are effectively computed on multiprocessors at high efficiency. Copyright © 2003 John Wiley & Sons, Ltd.     

An Efficient Boundary Handling with a Modified Density Calculation for SPH

We propose a new boundary handling method for smoothed particle hydrodynamics (SPH). Previous approaches required the use of boundary particles to prevent particles from sticking to the boundary. We address this issue by correcting the fundamental equations of SPH with the integration of a kernel function. Our approach is able to directly handle triangle mesh boundaries without the need for boundary particles. We also show how our approach can be integrated into a position‐based fluid framework.     

Catalytic conversion of organosilanes. 1. Disproportionation of alkylsilanes over solid acid and base catalysts

Catalytic conversions of diethylsilane (E2), triethylsilane (E3) and diethyldimethylsilane (E2M2) were examined at 373–573 K in a closed recirculation reactor by using various solid acid and base catalysts. Basically two types of reaction were found: decomposition and disproportionation. Strongly acidic catalysts such as silica-alumina (SA), alumina and sulfated ZrO₂ (SO₃/ZrO₂) exhibited high disproportionation activity, while weakly acidic and basic catalysts showed low catalytic activity and gave mainly cracking products. The order of disproportionation reactivity of three silanes tested were E2M2 > E3 > E2 over SA and SO₃/ZrO₂, while it was E2E3 > E2M2 over an alumina catalyst.