Evidence of high organotrophic potentiality of bacteria in the deep ocean

The organotrophic potentiality of heterotrophic microorganisms 50 cm above the ocean floor (5,207 m depth) was measured in situ, at a station in the subarctic Pacific Ocean (44° N; 154° E). In certain enriched deep-sea samples incubated in situ, the microorganisms exhibited nearly the same organotrophic activity as those in the surface water layers. Rod-shaped barophilic bacteria (0.4 to 0.6 μ x 1.0 to 2.0 μ), which multiplied at a generation time of about 10 h, were responsible for this activity.     

Evolutionary significance of prenuptial molting in female <Emphasis Type="Italic">Pagurus</Emphasis> hermit crabs

Molting and breeding entail major energetic costs for female crustaceans. However, females of some hermit crabs perform a molt immediately prior to copulation (prenuptial molt). The evolutionary significance of the prenuptial molt was examined in Pagurus hermit crabs, and two hypotheses were tested: (1) prenuptial molt might enhance the success of the present clutch by cleaning the pleopods of females and thereby preventing eggs from being dislodged from the pleopods, and (2) prenuptial molt might function for growth and increase future fecundity at the cost of energetic expenditure on the present brood. Although these hypotheses are not mutually exclusive, our results rejected the former hypothesis and supported the latter hypothesis. All four Pagurus species examined showed significant negative relationships between prenuptial molting and continuity of breeding; i.e., they showed high molting frequency after they had a long rest period from breeding. Females of P. minutus increased their size through the prenuptial molt, and showed a decreased clutch size due to the molt. The number of dislodged eggs increased if females molted in P. minutus. These results suggest that hermit crabs undergoing a prenuptial molt might not gain any clear immediate advantage of enhanced survival of eggs in the present clutch, and that the prenuptial molt would mainly contribute to growth.     

Investigation of the properties of the accidental release and explosion of liquefied dimethyl ether at a filling station

Dimethyl ether (DME) has been focused as a substitute for diesel fuel, and a number of studies have investigated engines fueled with DME because DME has a low auto-ignition temperature and does not generate particulate matter (PM). Therefore, in the last few years, the construction of DME filling stations for trucks in Japan has been planned. The introduction of DME vehicles requires expansion of DME supply stations, which in turn requires the collection of safety data and the establishment of safety regulations. The present paper describes an experimental investigation of the hypothetical scenario in which liquid DME is accidentally released and an explosion occurs. In the present study, large-scale leakage and ignition of DME were investigated and flame propagation data was obtained. We also measured the overpressure of the blast wave and the heat flux from the fireball. When the ignition position is near the nozzle, the flame propagation velocity is higher. The overpressure from the DME fireball is stronger than that from DME/air mixture deflagration. In summary, these results provide safety data for safety management of DME filling stations.     

A numerical method to predict flame fractal dimension during gas explosion

Accurate prediction of the flame propagation velocity during a gas explosion is essential to assess its consequences and to evaluate the risk level. The propagating premixed flame is self-turbulized due to the hydrodynamic instability, resulting in a fractal flame structure. It is therefore important for accurate prediction of flame speed to understand the flame’s fractal structure in detail and to predict its fractal dimension in particular. Numerical simulations of spherically-propagating flames have been previously attempted for such purposes. There are, however, difficulties to accurately predict the fractal dimension from the result of the numerical simulation of a spherically-propagating flame. In this study, we propose a method to easily predict the fractal dimension based on the numerical simulation of a planar flame. Planar flame propagation is simulated for different sizes of computational domain. The fractal dimension can be determined from the dependence of flame speed on computational domain size. The determined fractal dimension is favorably compared with previous experimental results.     

Development and evaluation of a mass spectrometer-based continuous emission monitor for volatile organic compound emissions from combustion devices

A mass spectrometer-based continuous emission monitor (MS-CEM) for organic compound emissions from combustion devices was developed and evaluated at the Louisiana State University (LSU) pilot-scale rotary kiln incinerator (RKI). The MS-CEM consists of a stack probe, heat-traced sampling line, vacuum pump, particulate filter, Nafion@ dryer and mass spectrometer. The mass spectrometer includes a computer that controls and optimizes the operation of the unit. The MS-CEM is capable of continuously analyzing up to 40 different volatile organic compounds on a real-time basis. The MS-CEM is capable of analyzing, computing and recording the analytical results for each and up to 40 different organic compounds in less than 0.3 s. Four different volatile organic compounds were mixed together and injected into the baghouse inlet while simultaneously analyzing each organic component exiting the RKI stack gas. The results obtained from MS-CEM were compared with the material balance values. The system response time (including the MS-CEM) varies from 1.1 to 1.5 min.