Siphon Principle Research Articles

A device for peritoneal dialysis

1. The siphon principle used in the hydrodynamic system of the PD device ensures ease of operation and reliability and rules out barotraumas of the organs of the abdominal cavity.

A simple system for self-cleaning of fish rearing tanks by periodic increase in water outflow

A system for effective removal of surplus food and fecal residues in fish rearing tanks is described. The system utilizes the siphon principle known from laboratory pipette washers, and is designed to work with the outflow of water through the center bottom outlet of the tank. When the siphon system is at work, all accumulated debris will be removed into the drain. A total emptying of tank by the siphon is avoided by breaking the outflow water column by an inlet of air. Air is introduced into the water column of the siphon at an appropriate water level by a narrow tube connected through the sidewall of the tank. Combined with a circular water current in the tank and a declining bottom toward the center, the system will effectively remove organic waste accumulated within each filling cycle of water. The biological advantages from periodic changes in water speed within fish rearing tanks is discussed.

Adjustable speed and vibration-free hydraulic system for Langmuir–Blodgett films deposition

Conventional apparatus for the dipping and raising of slides usually uses an electric motor with the slides fixed in a rigid holder. Most of the devices create a great deal of vibrations and this produces a nonuniform film deposition. We have used a new apparatus, which does not produce any vibrations of the slide, to build up Langmuir–Blodgett films. To move the slide, we employ a column of water and use the siphon principle, with speeds that can be varied between 3.0 and 120.0 mm min−1. An electronic circuit controls the automatic dipping and raising of the slide. A relay switches the solenoid valve to move the piston in the opposite direction. A machined Teflon trough and antivibration mount are used for the monolayer preparation. With this method, the deposition ratio usually obtained for the cadmium arachidate and chlorophyll a is 1.00±0.05. The absorption spectrum of multilayers of chlorophyll a give a linear relation between the absorbance at 680 nm and the number of layers up to 10. The nonlinear relation for the number of layers higher than 10 is explained by the presence of aggregates.

Gravitational effects on the distribution of pulmonary blood flow: hemodynamic misconceptions.

In the upright individual the apex of the lung receives relatively little blood. This has often been explained by the low pulmonary arterial pressure which is said to be just sufficient to raise the blood to the apex. It is believed that pulmonary arterial pressure must overcome the pressure due to gravity. This misconception overlooks the fact that the siphon principle applies to the vascular system in which the gravitational pressure of venous blood counterbalances the gravitational pressure of blood in the arteries and vice versa. Accordingly, the perfusion or driving pressure (P1-P2) between arteries and veins at any horizontal level of the lung remains unchanged, irrespective of body position. Intravascular pressure at any point is the algebraic sum of dynamic pressure causing flow (cardiogenic) and the pressure of blood due to gravity which does not cause flow. In the upright position, since the dynamic pressure in the pulmonary circuit is low, the drop in gravitational pressure at the apex of the lung reduces significantly the intravascular and, consequently, the transmural pressure in these vessels. The pulmonary microvessels being highly compliant undergo collapse and increase their resistance to flow. The reduction in apical flow is, therefore, a consequence of increased vascular resistance and not a matter of raising the blood against gravity. Gravitational pressure of blood per se neither hinders upward flow nor favors downward flow.

Simple extraction detector for the liquid chromatographic determination of secoverine in biological samples

A simple detection system for liquid chromatography based on post-column ion-pair extraction in a solvent-segmented stream is described. The fluorescent ion- pairing reagent 9,10-dimethoxyanthracene-2-sulphonate is added to the aqueous mobile phase prior to the column. An organic solvent, used for extraction of the ion pairs and for segmentation purposes, is added to the column effluent by gravity; about 70% of this phase is drawn through the detector cell using the siphon principle. The noise is significantly less than that of a system with a pulsating peristaltic pump. The system has been used for the detection of the prospective drug secoverine. Under optimized conditions, band broadening due to the extraction detection system is σt = 7 sec. The detection limit of secoverine is ca. 20 pg, the repeatability in the nanogram range is 2% (relative standard deviation) (L = 6) and the linearange is at least 4 decades. The use of a pre-column containing a 1-2-mm layer of stationary phase for clean-up and trace enrichment allows the direct injection of 200-1000 μl of plasma or serum. In this way, secoverine can be determined in the parts per 1012 range.

A siphon device for fractionation of runoff samples

Abstract A device is described for the continuous fractionation and sampling of water collected in agricultural runoff experiments. The device, which acts on the siphon principle, discards c, 95% of each volume aliquot collected and passes the remainder to storage for subsequent analyses.

Vascular hemodynamics: deep rooted misconceptions misnomers.

Erroneous concepts about vascular hemodynamics are widespread, notably as regards the effect of gravity on blood flow. Vascular pressure at any point is equal to the sum of two pressures of entirely different origins: (1) pressure caused by the pumping action of the heart ('cardiodynamic' pressure which is vital for circulation) and (2) pressure due to gravity acting on the blood ('gravitational' or hydrostatic pressure which plays no direct role in blood flow). Gravity neither helps nor hinders circulation because of the U tube or siphon principle. The gravitational energy of the column of blood in arteries is balanced exactly by the gravitational energy of the column in veins and vice versa. Thus, contrary to common belief, gravity does not hinder blood flow to the head in the upright position, nor does it hinder venous return from the dependent parts of the body. For this reason, in Poiseuille's equation, perfusion pressure should exclude gravitational pressure. Postural effects on circulation result from the distension vessels (particulary veins) subsequent to changes in gravitational pressure of blood.