Search results for "Capillary action"
showing 9 items of 179 documents
Fast Response Heating Module for Temperature Programmed GC Analysis in Microreaction Systems
2000
For monitoring the reactant and product concentrations of a gas phase microreactor for ethylene oxide synthesis the development of a miniaturised device for fast GC analysis suitable for operation in conjunction with the microreactor is advantageous. Therefore, a method employing short (0.2 – 0.4 m) packed capillary columns was developed. Highly crosslinked polystyrene microspheres proved to be the most suitable adsorbent enabling a high separation efficiency. For fast temperature programming design concepts for an efficient heating module capable to be used with short capillary columns were developed. In principle, planar as well as cylindrical designs are suitable for integration of a res…
Gas chromatographic study of acetyl derivates of chlorinated guaiacols
1982
The gas chromatography of acetyl derivatives of guaiacol and all chlorinated guaiacols has been studied on SE-30, OV-351 and Carbowax 20M capillary columns. The retention order and relative retention times under isotermal and temperature-programmed conditions are discussed. Different retention times for all mono- and dichloro compounds have been observed on the SE-30 column. However, all trichloroguaiacol isomers were separated only on polar columns. The best overall temperature-programmed separations have been achieved on an SE-30 capillary column.
New Glass Capillary Gas-Chromatographic Methods for Metabolites in Urine and Serum
1981
The analytical system suggested in this paper is a further development of pre-chromatographic methods and of column switching techniques described in previous papers1,2,3.In order to use modern gas-chromatographic techniques for the determination of metabolites in urine and serum quick and reliable pre-chromatographic methods for extraction, concentration and derivatization must be developed which give final (dosage) volumes of 5 to 10 μl with starting sample volumes of 0.1 ml of urine or 5 ml of serum as described by Dunges4.
Ionic Liquids on Demand in Continuous Flow
2009
We report on the development of an alternative protocol for the facile, solvent-free synthesis of various novel imidazolium-based ionic liquids (ILs) that affords highly pure products without the necessity of subsequent purification steps. The continuous approach is based on the combination of HPLC pumps with a micromixer and a capillary residence tube. Our system provides a high degree of control over the alkylation reactions due to a high surface-to-volume ratio and superior heat and mass transport. Within the scope of our studies, we focused on ionic liquids containing differently substituted phenyl rings and characterized these compounds with respect to further use for direct applicatio…
A study of physical processes in microplasma capillary discharges
2011
We continue the research of low-pressure capillary discharge lamps of 500 μ m in radius in Ar/Hg, Kr/Hg and Xe/Hg mixtures. In the previous paper, an experimental approach which combines the optical emission spectroscopy (OES) and tomographic methods was developed to study the capillary discharge. The present work is focused on interpretation of the tomographic reconstruction results for understanding the physical processes occurring in a capillary plasma. Analyzing the results of reconstruction, it was concluded that the radial profiles of Ar, Kr and Xe emission coefficients are in a good agreement with the Schottky theory. According to the Schottky model, ionization processes in plasma a…
Characterization of hydroxyaromatic compounds in vegetable oils by capillary electrophoresis with direct injection in an oil-miscible KOH/propanol/me…
2005
The separation of hydroxyaromatic compounds in vegetable oils, including synthetic antioxidants (3-tert-butyl-4-hydroxyanisol and 2,6-di-tert-butyl-4-hydroxytoluene), E-vitamers and other natural oil components, by nonaqueous capillary electrophoresis in an oil-miscible background electrolyte (BGE) was investigated. The BGE contained 40 mM KOH in a methanol/1-propanol (PrOH) mixture (15:85 v/v). The oil samples were 1:1 diluted with PrOH and directly injected in the capillary. Under negative polarity (cathode at the injection end), the anionic solutes moved faster than the electroosmotic flow, being well-resolved among them and from the triacylglycerols. Using virgin palm, extra virgin oliv…
Functional Morphology of Human Arteries During Fetal and Postnatal Development
1980
The equilibrium between the distending force of the blood pressure and the arterial wall is determined essentially by a simple law of mechanics, the law of Laplace. According to this law, the total force or tension (T) in the vessel’s wall represents the product of the radius of the vessel (r) and the blood pressure (p), T = r.p. The law of Laplace may be used to estimate and compare the tension produced by blood pressure in vessels of different size and thereby determine the increase in functional load on arteries. Since tension increases not only with blood pressure but also with the radius of the vessel, the highest tension is presumably produced in the wall of the ascending aorta where …
Optical Studies of the Capillary Refill Kinetics in Fingertips
2009
A new methodology for temporal analysis of the capillary refill processes by means of photoplethysmography (PPG) contact probe operating in the blue region of spectrum has been developed. A corresponding prototype device for finger measurements has been created and clinically tested. Results demonstrated that both AC and DC components of the blue PPG bio-signals are sensitive to the capillary occlusion and refill. Real-time measurements of the skin capillary refill kinetics by this technology can be used for noninvasive diagnostics of the peripheral perfusion disorders.
Evaluation of a lattice-Boltzmann method for mercury intrusion porosimetry simulations
2004
We have simulated intrusion of a non-wetting liquid into pores of varying shape and size. Simulations were based on the lattice-Boltzmann method and the Shan–Chen multiphase model. The liquid–solid contact angle for pores with circular cross-section was found to be equal to that for pores with square cross-section, and constant even for small pore sizes if the discretised shape of the circular cross-section was taken into account. For comparison, contact angle was also determined for a liquid column descending in a capillary tube, and the results were found to be consistent. Application of the method to mercury intrusion porosimetry is discussed.