The intermolecular interaction between 2-phenoxypropionic acid and β-bromo-cyclodextrin affixed on the stationary phase surface in a chiral HPLC system was studied by the moment analysis method. At first, pulse response and peak parking experiments were conducted to measure some parameters concerning the column geometry, adsorption equilibrium, and mass-transfer kinetics. Then, the first absolu...

Der Scale-up strukturierter Packungskolonnen ist ein zeit- und kostenintensiver Prozess. Um den Aufwand zur Ermittlung packungsspezifischer Kennzahlen zu reduzieren, wurde eine Messzelle für strukturierte Packungen entwickelt. Diese ermöglicht es charakteristische Bestandteile einer Packungskolonne im Labor-Maßstab abzubilden. Im Rahmen dieses Beitrages wird der Einfluss bei üblichen Randabweis...

Recent tests of a 250 m/m structured packing in a 1.22 m diameter column have produced some unanticipated results. Using two quite different systems, mass transfer performance in a relatively short 1.69 m bed was significantly better than previous results in a longer 3.78 m bed. No bed length effect was found on pressure drop. Two different severe vapor maldistributions were studied using a vac...

The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ε's, were calculated from the observed isotopic ratios at the front and rear boundaries of the neodymium adsorption band. The values of separation coefficients of neodymium isotopes, ε's, for the Nd-glycolate ligand exchang...

A novel liquid chromatographic system which enables high temperature ultrafast liquid chromatography (HTU-FLC) has been designed through the careful consideration of heat transfer, band broadening, and pressure drop. Studies of the effect of linear velocity on the HETP show that column efficiency at high velocity, especially of well-retained solutes, dramatically improves at higher temperatures...

HetR is an essential regulator of heterocyst development in cyanobacteria. HetR binds to a DNA palindrome upstream of the hetP gene. We report the crystal structure of HetR from Fischerella at 3.0 Å. The protein is a dimer comprised of a central DNA-binding unit containing the N-terminal regions of the two subunits organized with two helix-turn-helix motifs; two globular flaps extending in oppo...

Microdevices have been actively implemented in chemical processes, such as mixing and reactions. However, microseparation devices, excluding extraction are still under development. In distillation, the use of microdevices has expected to improve separation performance, their large specific surface area enables a rapid vapor–liquid equilibrium for temperature gradients be easily realized. this s...