Die zweite Geo‐Geum‐Brücke in Südkorea – Schrägkabelbrücke und Vorlandbrücke für Straßenverkehr mit Verbundfachwerkträger

The 2nd Geo Geum Grand Bridge in Korea – cable‐stayed bridge and approach bridge with composite truss girder for roadway traffic. The 2nd Geo Geum Grand Bridge forms part of the fixed connection from the mainland to the Island of Geo Geum in South Korea (Fig. 1). This high level crossing is composed of a 912 m long approach viaduct and a 1116 m long stay cable bridge with a main span of 480 m. The approach viaduct is a continuous girder with regular spans of 120 m. The superstructure of both bridges is a composite truss girder bridge, which carries a 2 lane highway on top and a pedestrian and bicycle way on the lower deck. The main design considerations were function as a high‐way, innovation in design and visual harmony with its surround‐ings. The stay cables are arranged in a single plane at the centre of the bridge, their semi‐fan arrangement with bundled configur‐ation gives a very special and unique appearance.     

Structure-Activity Studies Reveal Scope for Optimisation of Ebselen-Type Inhibition of SARS-CoV-2 Main Protease

The reactive organoselenium compound ebselen is being investigated for treatment of coronavirus disease 2019 (COVID-19) and other diseases. We report structure-activity studies on sulfur analogues of ebselen with the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) main protease (M^pro), employing turnover and protein-observed mass spectrometry-based assays. The results reveal scope for optimisation of ebselen/ebselen derivative- mediated inhibition of M^pro, particularly with respect to improved selectivity.     

Fast Burning Rocket Propellants Based on Silicone Binders – New Aspects of an Old System

Fast burning rocket propellants based on ammonium perchlorate (AP) and polydimethylsiloxane (PDMS) binders have been formulated and basically characterized in aluminized and non aluminized versions. The thermodynamic performance of PDMS bound propellants is limited by the evaporation point of silicon dioxide (crystobalite at 2863 K), which is formed during the combustion. The maximum specific impulses calculated with an expansion ratio of 70 : 1 are I_SP = 2340 N s/kg (238 s) for AP/PDMS and I_SP = 2430 N s/kg (247 s) for AP/Al/PDMS formulations. With a tri‐modal AP‐fraction of 200 μm, 30 μm and 2 μm it was possible to achieve processable propellants with 83% and 84% solid loading. They give burning rates close to 60 mm/s at 10 MPa and pressure exponents between 0.5 and 0.6 in the range of 7–25 MPa. The thermodynamic specific impulse of these systems was calculated to I_SP=2319 N s/kg (236 s) for AP/PDMS and I_SP=2403 N s/kg (245 s) for AP/Al/PDMS formulations at 70 : 1 expansion ratio. Measurements of the glass transition point by DMA and TMA detected a time dependent partial crystallization of the used PDMS close to T_G in the temperature range from −44 °C to −60 °C. Basic tests reveal high thermal and chemical stability with flash points over 300 °C and zero detonation sensitivity at 50 mm diameter. The property profile, so far determined, tends to fulfil the demands for applications as propellants with high burning rates and operating pressures together with a high thermal stability and a low vulnerability.     

Synthesis of Synthetic Lubricants by Trimerization of 1‐Decene and 1‐Dodecene with Homogeneous Chromium Catalysts

The Cr‐catalyzed trimerization of 1‐decene and 1‐dodecene is a highly selective method to synthesize C₃₀ and C₃₆ olefins. After hydrogenation, these products display very attractive viscosity indices (VI's). Due to the high trimer selectivity of the reaction no additional work‐up is needed to separate C₂₀, C₂₄ or C₄₀₊ oligomers from the product prior to a potential use of these products in synthetic lubricants for automotive applications.     

Einfache Darstellung von 4-Oxo-tetrahydropyrimidinen

Convenient Synthesis of 4-Oxo-tetrahydropyrimidines Enamino-nitriles as 6 or 11 yield 4-oxo-pyrimidines ( 2 ; 2a ; 10 ; 12a – c ) on treatment with cyclohexanone in basic media. Analogous compounds are obtained using acetone, butyraldehyde, benzaldehyde or substituted benzaldehydes.     

Vergleich verschiedener Ansätze zur nachhaltigen Olefinproduktion nach dem MtO- und FT-Verfahren

Olefins are an irreplaceable part of modern organic chemistry. According to the current state of the art, mostly crude oil is used as raw material, which is separated in a refinery. The naphtha fraction is then fed into a steam cracker, in which the hydrocarbons are cracked to the desired olefins. In this short communication, two alternative production processes are compared as a basis for alternative routes to the production of olefins.     

Date movement and control substrate for parallel adaptive applications

In this paper, we present the Data Movement and Control Substrate (DMCS), a library which implements low‐latency one‐sided communication primitives for use in parallel adaptive and irregular applications. DMCS is built on top of low‐level, vendor‐specific communication subsystems such as LAPI (Low‐level Application Programme Interface) for IBM SP machines, as well as on widely available message‐passing libraries like MPI for clusters of workstations and PCs. DMCS adds a small overhead to the communication operations provided by the lower communication system. In return, DMCS provides a flexible and easy to understand application program interface for one‐sided communication operations. Furthermore, DMCS is designed so that it can be easily ported and maintained by non‐experts. Copyright © 2002 John Wiley & Sons, Ltd.