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Flow characteristics in narrow-bore tubes. a) Turbulent flow, b) laminar flow, c) pulsed turbulent flow and d) hydrodynamic focusing.
Source publication
For a liquid flowing through a tube at constant velocity, the distance from the point of origin can provide a measure of the reaction time. This concept of continuous flow, first applied over a century ago to follow biochemical reactions by absorption spectroscopy, is now being used in conjunction with high-resolution structural methods such as X-r...
Contexts in source publication
Context 1
... the renewed interest in applying flow methods in structural biology, it is pertinent to review some critical aspects of flow. In order for distance of fluid flow along a conventional ageing tube to be a proxy for reaction time, it is important that the flow is turbulent (Figure 3a). If the flow is too slow, it becomes laminar and the velocity of the liquid in contact with the side walls becomes zero (Figure 3b). ...
Context 2
... order for distance of fluid flow along a conventional ageing tube to be a proxy for reaction time, it is important that the flow is turbulent (Figure 3a). If the flow is too slow, it becomes laminar and the velocity of the liquid in contact with the side walls becomes zero (Figure 3b). Consequently, the age of the reaction mix at any point along the tube becomes ill-defined, even though the net flow is constant. ...
Context 3
... v helps compensate, but this will shift the accessible time range to shorter values and may lead to excessive back pressure. One solution is to use pulsed flow where repetitive short but high-velocity pulses are applied to drive the solution through the ageing tube with a net slower velocity (Figure 3c). ...
Context 4
... effect of laminar flow can also be minimized using hydrodynamic focusing (Figure 3d). For two-dimensional hydrodynamic focusing, buffer is introduced on either side of the new mixed reactants to give a thin ribbon of reactant that is largely clear of the side walls and proceeds along the centre of the tube linearly with time. ...
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Citations
Herbert (Freddie) Gutfreund (hereafter called Freddie) made fundamental contributions to molecular enzymology—a name he introduced into the UK Biochemical Society as its first subgroup and as a discipline within the field of biochemistry. Freddie was born in Austria but moved to the UK in 1938, aged 17, during the upheavals across Europe leading up to World War II. He initially worked as a farm hand before his motivation in science took him first to the University of Liverpool, then Imperial College London as a Research Assistant, and on to Cambridge University. His experiences in Cambridge and the friends he made there during the foundation of modern molecular biology in the 1950s remained a major influence throughout his later career. He spent a short period at the National Dairying Research Institute near Reading, followed by the major part of his career at Bristol University, where he founded the Molecular Enzymology Laboratory within the Department of Biochemistry. He developed and encouraged a school of physical biochemistry built especially around the field of transient kinetics of enzyme-catalysed reactions. Freddie will probably be remembered most for the impact he made in his journal publications and through his four books, written over more than four decades, each around some aspect of molecular enzymology.
