36 research outputs found
Oxidation Reactions in Segmented and Continuous Flow Chemical Processing using a N-tert-Butylsulfinimidoyl chloride monolith
No full textBivalent ligands for the β₂ adrenergic receptor
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
Integrity and Fracture Response of Offshore Pipelines Subject to Large Plastic Strains
No full textSteel pipelines are widely used in offshore oil/gas facilities. To achieve economically feasible designs, regulatory codes permit utilization of the pipelines well past their elastic response limit. This requires thorough integrity check of the pipeline subject to large scale yielding (LSY). Engineering criticality assessments (ECA) are used to justify the integrity of a cracked pipeline against fracture failure. The currently used ECA crack driving force equation was developed for load-controlled components subject to very limited crack-tip plasticity. Moreover, fracture toughness data are extracted from deeply-cracked laboratory specimens that produce the lowest margin of toughness values. Therefore, the current framework can be overly conservative (or include non-uniform inaccuracies) for ECA of modern pipelines that undergo LSY and ductile crack growth prior to failure. The two main goals of this thesis are: (i) Development of an alternative crack driving force estimation scheme, (ii) Justification of the use of use of shallow-cracked single edge notch tensile (SENT) specimens for the ECA. Strain concentration in concrete coated pipelines, and effect of Lüders plateau on the fracture response are also investigated.
A new reference strain J-estimation scheme is proposed and calibrated to 300 nonlinear parametric FE models, which takes advantage of the linear evolution of the J with LSY bending strains. The scheme is hence strain-based and needless of limit load solutions, providing additional accuracy and robustness.
The near-tip stress and strain fields of cracked pipelines were also investigated and compared to those obtained from a K-T type formulation. It is shown that the J-Q constraint theory can satisfactorily characterize these fields up to extreme plastic bending levels. Similar J-Q trajectories were also observed in the SENT and pipeline models. Subsequently, FE models utilizing a voided plasticity material were used to parametrically investigate ductile crack growth and subsequent failure of pipelines subject to a biaxial stress state. Plastic strain and stress triaxiality fields ahead of the propagating crack, along with R-curves, were compared among SENT and pipeline models. It is concluded that the SENT specimen could be a viable option for ECA of such pipes based on the observed crack tip constraint similarity
G-protein coupled receptor dimerization
No full textA growing body of evidence suggests that GPCRs exist and function as
dimers or higher oligomers. The evidence for GPCR dimerization comes
from biochemical, biophysical and functional studies. In addition,
researchers have shown the occurrence of heterodimerization between
different members of the GPCR family. Two receptors can interact with
each other to make a dimer through their extracellular loops,
transmembrane helices and intracellular loops. The nature of bonds
between two receptors can vary from covalent (e.g. disulphide bonds) to
non-covalent (for instance hydrophobic interactions between
trans-membrane helices or coiled coil structures) or a combination of
both. Dimerization can occur in and affect different stages of a
receptor's life, namely trafficking, signaling and internalization, and
can be seen as the natural way to regulate receptor activity or
increase the functional repertoire of proteins. Different structures
for GPCR dimers have been proposed, for example a simple contact dimer
or an interlocking domain-swapped structure. Here we introduce some of
the information available on GPCR dimerization, which includes early
studies that had been dismissed until the relatively recent past and
some of the more recent data which has vindicated these early studies
agonists and their biological evaluation through the use of in-line frontal affinity chromatography
No full textThe application of flow microreactors to the preparation of a family of casein kinase I inhibitors
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ChemInform Abstract: Key Routes to the Best-Selling 5-Membered Ring Heterocyclic Pharmaceuticals
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