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R D Yang

Publications and source records attributed to R D Yang.

22 records · Page 2Linked to original sources
PubMed1975

Dynamic and steady state studies of phenol biodegradation in pure and mixed cultures.

The microbial degradation of phenol by pure and mixed cultures of Pseudomonas putida was studied in batch, phenol-stat, and continuous culture systems. In the continuous culture runs, both steady state and transient experiments were performed. From these experiments, a model for the kinetic behavior of the organisms was evolved and an analysis performed on the stability and dynamic behavior of pure and mixed cultures. The results indicate that it should be possible to achieve phenol removal from wastewaters down to levels of 1-2 ppm in a single state system. However, because of the effect of substrate inhibition on kinetic behavior of the microorganisms, long lasting transients can occur. The transient behavior of such systems cannot be solely determined from mumax or Ks parameters, but must include a consideration of the transient size and response characteristic of the organism.

Kinetics↗
PubMedDate not supplied

The epidemiology of lung cancer in Xuan Wei, China: current progress, issues, and research strategies.

In Xuan Wei, a rural Chinese county of about one million people, females' annual lung cancer mortality is China's highest, and males' is among China's highest. Xuan Wei's very high indoor air pollution levels (sometimes exceeding 20 mg/m3), residentially stable population, relatively uncomplicated lifestyle, and wide geographic variation in lung cancer mortality render it highly amenable to quantitative, interdisciplinary investigation of chemical carcinogens due to indoor air pollution. To date, epidemiologic findings reveal a closer association of lung cancer with the indoor burning of "smoky" coal (as opposed to "smokeless" coal or wood) than with tobacco use or occupation. Current aerometric, chemical, and toxicologic findings tend to confirm this association, though the specific carcinogenic constituents of Xuan Wei indoor air pollution have not yet been determined. Chinese and American investigators are conducting interdisciplinary field and laboratory investigations to quantify the lung cancer risk attendant on indoor air pollution relative to other factors, to measure and compare the characteristics of pollution from different Xuan Wei fuels, to determine the relative etiologic importance of pollution composition and concentration, and to develop quantitative relationships between air pollution dose and lung cancer risk.

Adult↗