[Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

Separation of bovine serum albumin by foam fractionation with wire gauze structured packing column.

In order to enhance foam drainage, a novel foam fractionation column with the wire gauze structured packing was developed. The performances of the packing were evaluated by investigating its effects on bubble size, liquid holdup, enrichment ratio, and recovery percentage efficiency under different conditions using bovine serum albumin (BSA) aqueous solution as a model. The results showed that the packing could accelerate the bubble collapse, reduce the liquid holdup, enhance the foam drainage, and improve the BSA enrichment ratio. Specifically, the best BSA enrichment ratio was 21.78 at the liquid loading volume of 490 mL, air flow rate of 300 mL min(-1), feeding BSA concentration of 0.10 g L(-1), packing bed height of 300 mm, and feeding pH 6.2. It was 2.44 times of the BSA enrichment ratio obtained with the control column.