This application note describes the separation of caffeine on C18 resin using the MultiColumn Countercurrent Solvent Gradient Purification (MCSGP) process. The KNAUER Contichrom® system that is offered in a cooperation of KNAUER and Chromacon is the only system on the market, which can be used in MCSGP mode for difficult separations of biological or non-biological compounds. MCSGP is a counterc...

TRUETA et al. proposed in 1947 that morphological differences between renal cortical and medullary structures reflect a '"fundamental difference in the function of the cortical and juxtamedullary vasculonephric units.' This proposition was reinforced when Wirz et al. first published evidence for the countercurrent mechanism as the basis for urinary concentration in 1951. The countercurrent hypo...

Purification of concentrated manganese sulfate solution by solvent extraction is discussed in this paper. The use bis(2-ethylhexyl) hydrogen phosphate (D2EHPA) and bis(2,4,4-trimethylpentyl)phosphinic acid (BTMPPA) was studied removal impurities from zinc electrowinning anode sludge leachates. Over 99 % iron were removed both extractants at around pH 3 two mixer-settlers operating continuous co...

The Contichrom® CUBE Combined and Contichrom HPLC systems use batch and continuous periodic countercurrent (PCC) processes for purification of target proteins, peptides, and small molecules. Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) is a unique PCC polishing process that provides superior yield and purity at high productivity. In order to keep the MCSGP process at an opti...

TRUETA et al. proposed in 1947 that morphological differences between renal cortical and medullary structures reflect a '"fundamental difference in the function of the cortical and juxtamedullary vasculonephric units.' This proposition was reinforced when Wirz et al. first published evidence for the countercurrent mechanism as the basis for urinary concentration in 1951. The countercurrent hypo...

(1997) Analytica Chimica Acta 344: 241}249. 23. Llompart MP, Lorenzo RA, Cela R, PareH JRJ, BeH langer JMR and Li K (1997) Journal of Chromatography A 757: 153}164. 24. Llompart MP, Lorenzo RA, Rosa A, Cela R, Li K, BeH langer JMR and Pare JRJ (1997) Journal of Chromatography A 774: 243}251. 25. Chee KK, Wong MK and Lee HK (1996) Journal of Liquid Chromatography and Related Technology 19: 259}2...

MARSH, DONALD J., AND LEE A. SEGEL. Analysis of countercurrent di$usion exchange in blood vessels of the renal medulla. Am. J. Physiol. 221(3): 817-828. 1971 .-A model of the vasa recta was developed to explore the significance of dissimilarities between ascending and descending vasa recta for countercurrent exchange efficiency, and also to examine the interaction between countercurrent exchang...

• Adaptations to desert life have attracted much interest in the past forty years." In addition to the physiological aspects of this subject, there are morphological signs of adaptation to an arid environment in the kidneys of desert animals when compared to the kidneys of animals that require free access to water for their normal life. One of the distinguishing features of the former is the lo...

We study a solute concentrating mechanism that can be represented by coupled transport equations with specific boundary conditions. Our motivation for considering this system is urine concentrating mechanism in nephrons. The model consists in 3 tubes arranged in a countercurrent manner. Our equations describe a countercurrent exchanger, with a parameter V which quantifies the active transport. ...