Biomedical subjects

I Baek

Publications and source records attributed to I Baek.

3 recordsLinked to original sources

PubMed2000

A dosimetric model for inhaled radioactive gases.

Mathematical simulation models have been used to study transport of insoluble and nonreactive gases for more than twenty years. However, gas and vapor transport and uptake still are not well understood, and a mathematical model for slightly soluble and nonreactive gas transport and uptake still has not been developed. This paper describes the development of a mathematical model of diffusion, convection, lateral transport into the airway wall, and alveolar absorption for inhaled radioactive gases in human conductive and respiratory airways. The model is based on a single-path trumpet-bell model. Sensitivity studies were conducted to ascertain the influence on the final model of the functional residual capacity, the tidal volume and diffusivity and solubility. Results obtained with this model are presented for HT gas exposure and are compared with other findings. In general, the results obtained in this research are in good agreement with other mean experimental results.

Air Pollutants, Radioactive↗

PubMed1999

Volatile release from aqueous solutions under dynamic headspace dilution conditions.

Static equilibrium was established between the gas phase (headspace) and an unstirred aqueous phase in a sealed vessel. The headspace was then diluted with air to mimic the situation when a container of food is opened and the volatiles are diluted by the surrounding air. Because this first volatile signal can influence overall flavor perception, the parameters controlling volatile release under these conditions are of interest. A mechanistic model was developed and validated experimentally. Release of compounds depended on the air-water partition coefficient (K(aw)) and the mass transport in both phases. For compounds with K(aw) values <10(-)(3), K(aw) was the factor determining release rate. When K(aw) was >10(-)(3), mass transport in the gas phase became significant and the Reynolds number played a role. Because release from packaged foods occurs at low Reynolds numbers, whereas most experiments are conducted at medium to high Reynolds numbers, the experimentally defined profile may not reflect the real situation.

Food Handling↗

PubMed1999

Sensory perception is related to the rate of change of volatile concentration in-nose during eating of model gels.

The relationship between perceived aroma and the volatile concentration measured in-nose was investigated during eating of a model food. Sensory ranking and time-intensity analysis (TI) were used to measure perceived aroma, while in-nose volatile concentration was monitored by atmospheric pressure ionization mass spectrometry, which produced time release data. A gelatine-sucrose gel with a range of gelatine concentrations (2-8% w/w) and flavoured with furfuryl acetate was used as the model food. Sensory scaling showed decreased flavour intensities and TI showed a decrease in the flavour perceived over time, as the gelatine concentration increased. Studies in model systems and in people demonstrated that the different rates of release observed for different gelatine concentrations were not due to binding of volatile to protein in the gel, nor to mucous membranes, but were due to different rates of gel breakdown in-mouth. There were no significant differences in the maximum in-nose volatile concentrations for the different gelatine concentrations, so the amount of volatile present did not correlate well with the sensory analysis. However, the rates of volatile release were different for the different gels and showed a good correlation with sensory data.

Acetates↗