A review of floating semisubmersible hull systems:Column stabilized unit

Abstract Column stabilized semisubmersible is one of the most commonly used hull systems for the design and development of drilling and production platforms used for offshore deep water operations. Recent reconfiguration and design alterations have improved its hydrodynamic behaviour in rough weather conditions and, thus, its application and functionality in ocean engineering. Semisubmersible dry-trees applications and large wind turbine foundation systems in ultra-deep waters require high payload integration for reduced motion responses in all degrees of freedom. This paper presents a review of recent industrial and academic contributions to the development of column stabilized semisubmersible hulls used for deep water operations. It also provides an overview of the motion and structural attachments of semisubmersibles. The type and formation of dry-trees semisubmersibles are discussed. The dynamic behaviour and comparative advantages of them are also explained

Direct Arylation of Adenine by Fluoro- and Chloronitrobenzenes: Effect of Microwaves

<div><p></p><p>Direct arylation of adenine with fluoro- and chloronitrobenzenes leads to mixtures of <i>N</i>9 and <i>N</i>7 substituted adenines. After separation by column chromatography, the individual isomers can be efficiently hydrogenated on Pd to give the corresponding aminophenyladenines. A significant enhancement of the reaction rate by microwave irradiation was observed. This two-step procedure was found to be a feasible route to otherwise hardly available 7-aminophenyladenines. Correlation between calculated shielding constants and experimental values of chemical shifts in ¹³C and ¹⁵N NMR was used for assignment of the site of substitution.</p> <p>[Supplementary materials are available for this article. Go to the publisher's online edition of <i>Synthetic Communications</i>® for the following free supplemental resource(s): Full experimental and spectral details.]</p> </div