Small Volume Flow Research Articles

A method to study reaction kinetics over finely-dispersed catalysts in stationary and non-stationary conditions

The application of a small-volume gradientless flow reactor with a vibrofluidized catalyst bed, mass-spectrometric analysis of the reaction products and a membrane turbulizer for alternate purging of the reactor filters by the reaction mixture permits to study the kinetics of complex catalytic reactions over catalysts with 50–100μm grains in both stationary and nonstationary conditions.

Design assembly of an inexpensive, automated microbore amino acid analyzer: separation and quantitation of amino acids in physiological fluids.

An amino acid analyzer capable of separating and quantitating 0.5 to 20 n moles of each ninhydrin-positive compound in physiological fluids has been designed and assembled from commercially available components. The buffer sequence, column temperature change and sample application are controlled by an automatic programmer constructed from a series of timers. The liquid delivery protion of the instrument consists of a series of polystyrene and stainless steel chambers pressurized with argon and connected through valves and manifolds to conventional positive displacement pumps. The column is highly polished stainless steel tubing (0.21-cm ID) packed with 9-mu cation exchange resin. Micro colorimeters, equipped with appropriate interference filters and small-volume (2-8 mu 1) flow cells, are used as detectors. The sample loader is a dual 20-port automatic valve containing 25-mu1 sample loops. Small-bore teflon tubing (32 AWG), interconnected with tubing adapters and connectors, is used for buffer lines and reaction coil (100 degree C); ninhydrin lines are 1/16-inch stainless steel tubing. Separation of 42 ninhydrin positive compounds, including column equilibration, is accomplished in 5 hours. Procedures for the extraction of amino acids from physiological fluids and tissues as well as the preliminary clean-up of these extracts are also described.

Fluid flow in the human foetal lung: A theoretical model

A theoretical model is developed to predict pressure changes and velocity profiles within the foetal lung during its sporadic bursts of activity. Because of the small volume flow rates and relatively high frequencies, the linearised, unidirectional Navier-Stokes equations are used to calculate these values. About 70% of the pressure drop occurs in the first four generations and is an order of magnitude higher than the equivalent Poiseuille pressure drop. Velocity profiles, pressure falls within each generation together with the total pressure drop at different times during the cycle are illustrated.

Design of a wind-tunnel metabolism chamber for small animals.

ArticleDesign of a wind-tunnel metabolism chamber for small animals.J A GessamanJ A GessamanPublished Online:01 Aug 1972https://doi.org/10.1152/jappl.1972.33.2.255MoreSectionsPDF (239 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat "Design of a wind-tunnel metabolism chamber for small animals.." Journal of Applied Physiology, 33(2), p. 255 Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByA wind tunnel metabolism chamber with small volume and good air flow characteristics27 November 2000 | Journal of Physics E: Scientific Instruments, Vol. 22, No. 12Measurement of simultaneous effects of air temperature, wind speed and short-wave irradiance on animal metabolism: a wind tunnel design29 November 2000 | Journal of Physics E: Scientific Instruments, Vol. 21, No. 9 More from this issue > Volume 33Issue 2August 1972Pages 255 https://doi.org/10.1152/jappl.1972.33.2.255PubMed5054435History Published online 1 August 1972 Published in print 1 August 1972 Metrics

Evaluation of linear gradient loaded columns in temperature programmed gas chromatography

The performance of gradient loaded columns in temperature programmed gas chromatography has been evaluated. It was found that the elution temperatures and elution times are independent of the type of gradient (positive, negative or no gradient). At optimal working conditions (small injection volume and optimal carrier gas flow) resolution is best with evenly loaded columns, intermediate for columns with negative gradient and worst for columns with positive gradient. When deviating from optimal carrier gas velocity, resolution decreases much more for evenly loaded columns than for gradient columns. On increasing the injected volume, the decrease in resolution is much more pronounced for columns with positive gradient and no gradient than for columns with negative gradient. Thus, columns with negative gradient are superior to evenly loaded columns when large injection volumes are required. It is suggested that columns with negative liquid load gradient could prove especially useful in preparative temperature programmed gas chromatography.

Small volume flow cell for simultaneous polarographic, coulometric, and spectrophotometric measurements

Small volume flow cell for simultaneous polarographic, coulometric, and spectrophotometric measurements

An electromagnetic blood flowmeter for measuring blood flow to the oral region of anaesthetized experimental animals

An A.C. electromagnetic blood flowmeter capable of recording the small volume flows occurring in the arteries supplying the oral tissues has been constructed. The cannula and the magnetic head construction require the interruption and cannulation of the vessels. The amplifier consists of five stages in a cascade arrangement and incorporates a small amount of negative feedback. The maximum amplifier gain is in excess of one million. The output, which is proportional to the volume blood flow, is recorded on an ink-writing oscillograph. The high amplifier gain and precise phase monitoring system permit blood-flow determinations as small as one millilitre per minute.