Pyrococcus furiosus represents one of the most important hyperthermophilic bacteria isolated thus far because of its relatively high cell yields and rapid growth rates. Pyrococcus furiosus exhibits several interesting growth characteristics, especially in terms of biotic gas production, which were examined in this study. In the presence of elemental sulfur, both carbon dioxide and hydrogen sulfide production appeared to be strongly growth associated, while no significant hydrogen production was observed. In the absence of sulfur, hydrogen and carbon dioxide were produced by the organism and hydrogen inhibition was observed. The addition of elemental sulfur to the medium apparently eliminated, hydrogen inhibition as growth proceeded normally even when hydrogen was added to the gas phase. Also, no apparent substrate limitation or toxic product could be attributed to the cessation of growth as cell growth in spent media was at least as good as in fresh media. An unstructured growth model was used to correlate growth and gas production for P. furiosus in complex seawater-based media at 98 degrees C both in the absence and presence of elemental sulfur. The model was shown to be useful for examining some of the observations made in this study.
Apoptosis plays a crucial role in the occurrence of cancer and other diseases. Real-time monitoring of the cell apoptosis process has great significance for cell viability and drug screening. Herein, a novel fluorescent probe was constructed based on the fluorescence resonance energy transfer mechanism, which track the sensitivity of polarity changes, as well as detect the drug-induced cell apoptosis process in a dual-color mode. Importantly, the change of cellular microenvironmental polarity makes it possible to dynamically visualize the process of drug-induced cell apoptosis. More significantly, the designed probe targeted the lysosomes in the living cells to give a blue emission, and it accumulated on the plasma membrane to display red fluorescence during the drug-induced cell apoptosis process. Thus, cell viability could be monitored by both the localization and emission colors of the robust probe. We expect that the unique probe can provide a new blueprint for evaluating and screening apoptosis-related drugs.
In this paper, a theoretical analysis of oxygen transport across the tubular microporous membrane is described. This analysis has provided some insight into the optimal design of the membrane aerator. It was found in this study, at fixed inlet pressure, that the overall membrane oxygen transfer rate increases with increased tubing length only up to a certain length, i.e., the "critical length". When a large membrane surface area is required, the fiber should be divided into parallel segments to increase the overall oxygen transfer rate. A manifold or a gas distributor can then be used to distribute gas into segments of tubing. The length of each segment cannot exceed the critical length. In addition, shorter tube segments should give a higher oxygen transfer rate per unit tube length; however, this advantage is counterbalanced by the fact that gas distribution into huge numbers of parallel tubings may not be uniform.
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