Theoretical evaluation of the advantages and limitations of constant pressure versus constant flow rate gradient elution separation in supercritical fluid chromatography

2013 ◽  
Vol 1312 ◽  
pp. 134-142 ◽  
Author(s):  
Ruben De Pauw ◽  
Gert Desmet ◽  
Ken Broeckhoven
Keyword(s):  
Supercritical Fluid ◽  
Supercritical Fluid Chromatography ◽  
Flow Rate ◽  
Constant Pressure ◽  
Gradient Elution ◽  
Constant Flow ◽  
Theoretical Evaluation ◽  
Constant Flow Rate ◽  
Rate Gradient

Kinetic performance limits of constant pressure versus constant flow rate gradient elution separations. Part I: Theory

2011 ◽  
Vol 1218 (8) ◽  
pp. 1153-1169 ◽  
Author(s):  
K. Broeckhoven ◽  
M. Verstraeten ◽  
K. Choikhet ◽  
M. Dittmann ◽  
K. Witt ◽  
...  
Keyword(s):  
Flow Rate ◽  
Constant Pressure ◽  
Gradient Elution ◽  
Constant Flow ◽  
Performance Limits ◽  
Constant Flow Rate ◽  
Rate Gradient

Kinetic performance limits of constant pressure versus constant flow rate gradient elution separations. Part II: Experimental

2011 ◽  
Vol 1218 (8) ◽  
pp. 1170-1184 ◽  
Author(s):  
M. Verstraeten ◽  
K. Broeckhoven ◽  
M. Dittmann ◽  
K. Choikhet ◽  
K. Witt ◽  
...  
Keyword(s):  
Flow Rate ◽  
Constant Pressure ◽  
Gradient Elution ◽  
Constant Flow ◽  
Performance Limits ◽  
Constant Flow Rate ◽  
Rate Gradient

Effects of the Gas Feed on Bubble Formation in a Microfluidic T-Junction: Constant-Pressure versus Constant-Flow-Rate Injection

2019 ◽  
Vol 58 (23) ◽  
pp. 10092-10105 ◽  
Author(s):  
Sheng Mi ◽  
Netsanet Tesfaye Weldetsadik ◽  
Zafar Hayat ◽  
Taotao Fu ◽  
Chunying Zhu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Constant Pressure ◽  
Bubble Formation ◽  
Constant Flow ◽  
Constant Flow Rate

On elastic regime of filtration in hydraulic fracture

2016 ◽  
Vol 11 (2) ◽  
pp. 156-166
Author(s):  
V.Sh. Shagapov ◽  
Z.M. Nagaeva
Keyword(s):  
Pressure Drop ◽  
Rheological Properties ◽  
Flow Rate ◽  
Analytical Solutions ◽  
Hydraulic Fracture ◽  
Constant Pressure ◽  
Constant Flow ◽  
Exact Analytical Solutions ◽  
Constant Flow Rate ◽  
Pressure Evolution

Fluid recovery from a well in the modes of constant pressure drop and constant flow rate is considered basing on a theoretical model of filtration in a hydraulic fracture. Exact analytical solutions are obtained that allowed analyzing the effect of the reservoir and fracture properties (such as porosity, permeability and crack width) as well as the rheological properties of the saturating fluid upon: pressure evolution in the fracture, well flow rate at constant pressure drop, and pressure evolution in the wellbore. On the basis of theoretical models describing the filtration for a crack in an oil or gas reservoirs, the considered problem on the selection of fluids from the well in modes constant differential pressure and constant flow. For the considered tasks are received exact analytical solutions, based on which we analyzed the influence of reservoir characteristics of the formation and fractures (for example, their porosity, permeability and width of cracks) and the rheological properties of the saturating fluid on the evolution of the pressure in the fracture, the production rate at a constant differential to the dynamics of the pressure in the well.

scholarly journals Effects of Calcium Entry Blocker Emopamil on Postischemic Energy Metabolism of the Isolated Perfused Rat Brain

1987 ◽  
Vol 7 (4) ◽  
pp. 489-496 ◽  
Author(s):  
Gerhard Wilhelm Bielenberg ◽  
Heinz Haubruck ◽  
Josef Krieglstein
Keyword(s):  
Energy Metabolism ◽  
Flow Rate ◽  
Constant Pressure ◽  
High Energy ◽  
Calcium Entry ◽  
High Energy Phosphates ◽  
Calcium Entry Blocker ◽  
Constant Flow ◽  
Constant Flow Rate ◽  
Entry Blocker

The effects of emopamil on postischemic energy metabolism and electroencephalographic (EEG) recovery were investigated in the isolated rat brain perfused at either constant pressure or, alternatively, at constant flow rate. Flow rate and perfusion pressure were monitored continuously. The brains were perfused with a fluorocarbon emulsion for 30 min, and after 30 min of ischemia, perfusion was reinstituted for 5, 30, or 60 min. Global cerebral perfusion rate was increased by emopamil throughout the perfusion period and, accordingly, in brains perfused at a constant flow rate, perfusion pressure was reduced by the drug. At constant pressure perfusion, after 5 min after ischemia, cortical levels of creatine-phosphate, adenosine triphosphate (ATR), glucose, glucose-6-phosphate, and fructose-6-phosphate were higher in emopamil-treated brains than in controls, although the levels of adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were reduced. When brains were perfused at constant flow rate, however, emopamil exhibited no effect on brain energy metabolism in the early reperfusion period. Postischemic restoration of high-energy phosphates proved to depend on the flow rate used. After 30 min of postischemic reperfusion, cortical levels of lactate were lower in emopamil-treated brains compared to controls at both constant pressure and constant volume perfusion. Postischemic lactate levels were independent of flow rate and were also reduced when emopamil was only present during reperfusion. The postischemic restoration of cortical EEG activity was improved by the calcium entry blocker. The results suggest that the restoration of high-energy phosphates during the early postischemic recovery can be mainly attributed to the vascular effect of emopamil, whereas the lower lactate levels are caused by a direct action of the calcium entry blocker on brain parenchyma.

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