The marine archaebacterium Methanococcus jannaschii was studied at high temperatures and hyperbaric pressures of helium to investigate the effect of pressure on the behavior of a deep-sea thermophile. Methanogenesis and growth (as measured by protein production) at both 86 and 90°C were accelerated by pressure up to 750 atm (1 atm = 101.29 kPa), but growth was not observed above 90°C at either 7.8 or 250 atm. However, growth and methanogenesis were uncoupled above 90°C, and the high-temperature limit for methanogenesis was increased by pressure. Substantial methane formation was evident at 98°C and 250 atm, whereas no methane formation was observed at 94°C and 7.8 atm. In contrast, when argon was substituted for helium as the pressurizing gas at 250 atm, no methane was produced at 86°C. Methanogenesis was also suppressed at 86°C and 250 atm when the culture was pressurized with a 4:1 mix of H2 and C02, although limited methanogenesis did occur when the culture was pressurized with H2.

Infrared spectroscopy has been used to study the evolution of polyurethane foam structure, providing measures of relative reaction kinetics, hard segment growth, the onset of phase separation, the formation of order, and the development of final morphology. Changes in free, monodentate, and bidentate hydrogen-bonded urea groups dominate the organization of the entire ensemble. Hard segments formed by reaction of 2,6-toluene diisocyanate (2,6-TDI) and by a mixture of 80% 2,4-TDI and 20% 2,6-TDI displayed very different local segmental alignment, a factor crucial in the development of morphology. Phase separation occurred faster, with fewer and shorter hard segments, in the systems with well-ordered straight chains. The formation and time evolution of monodentate ureas suggest that phase development may be incomplete, or trapped, in systems with ill-defined urea structures. A low degree of spatial order exists in the systems containing these structures.

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Decomposition products of fiberglass composites used in construc tion were identified using Fourier transform infrared (FT-IR) spectroscopy. This bench-scale study concentrated on identification and quantification of toxic species. Identifying compounds evolved during thermal decomposition provides data to develop early fire detection systems as well as evaluate product fire safety performance. Material fire behavior depends on many factors. Ventila tion, radiant heat flux, and chemical composition are three factors that can be modeled. Physical observations of composites during thermal decomposition with simultaneous identification and quantification of evolved gases offer re searchers in both material development and fire safety an advancement in the state-of-the-art for material testing. Gas analysis by FT-IR spectroscopy iden tified toxic effluent species over a wide range of composite exposure tempera tures (100 to 1000 ° C), during pyrolysis and combustion. Fiberglass composites with melamine, epoxy, and silicone resins were profiled. Formaldehyde, meth anol, carbon monoxide, nitric oxide, methane, and benzene were identified by the spectral analysis prior to physical evidence of decomposition. Toxic concen trations of formaldehyde, carbon monoxide, nitric oxide, ammonia, and hydro gen cyanide were observed as thermal decomposition progressed.

We describe a high-pressure reactor system suitable for simultaneous hyperbaric and hydrostatic pressurization of bacterial cultures at elevated temperatures. For the deep-sea thermophile ES4, the growth rate at 500 atm (1 atm = 101.29 kPa) and 95°C under hydrostatic pressure was ca. three times the growth rate under hyperbaric pressure and ca. 40%o higher than the growth rate at 35 atm.