Investigation of the action of flame retardants in cellulose. I. Investigation of the flame retardant action of 2,2′-oxybis(5,5-dimethyl-1,3,2-dioxaphosphorinane-2,2′-disulfide) in cellulose

Pyrolysis experiments were performed in high vacuum and under reduced air pressure (100 Pa). The volatile products of pure cellulose and cellulose containing various amounts of flame retardant 2,2′-oxybis (5,5-dimethyl-1,3,2-dioxaphosphorinane-2,2′-disulfide), i.e., Sandoflam 5060 of Sandoz AG, were studied by means of gas chromatography in combination with mass spectroscopy. The volatile products were characterized with infrared spectroscopy. The studied revealed that the incorporation of the flame retardant enhanced the water release and shifted the onset of this reaction to lower temperature. On the basis of these findings an explanation for the mechanism of flame retardancy in generated cellulose fibers modified with this particular flame retardant is attempted. From experiments with different residual air pressure the influence of oxygen on the primary processes of the pyrolytic degradation of cellulose is being discussed.     

High speed propulsion: Performance advantage of advanced materials

High-speed air breathing propulsion systems have many attractive military and civil applications. The high propulsive efficiency of these systems allows the exploitation of speed, distance, and bigger payloads, or any combination of the three. The severe operating conditions of these systems require particular attention to overall thermal management of the engine/air-frame. Fuel-cooling the engine structure is a viable way of maintaining thermal balance over a range of flight conditions. Air Force applications have focused on using endothermic hydrocarbon fuels to address this issue because of their compatibility with the military operations. Recent ground tests of scramjet engines have demonstrated adequate performance utilizing state-of-the-art technology in materials. This progress has paved the way for an expendable flight test vehicle in the near future. In order to take full advantage of the capabilities of this propulsion system, advances in fuel-cooled structures, high temperature un-cooled materials, and increased heat capacity of hydrocarbon fuels will be needed to enable expendable systems to reach higher Mach numbers. An additional benefit would be realized in future reusable systems.     

Isolation and characteristics of a protein-polysaccharide complex, secreted by Bifidobacterium adolescentis

Although self-help/mutual-help groups, like Alcoholics Anonymous, are important factors in the recovery of many chemically dependent individuals, the large dropout rates from such groups and the awareness that many who drop out do not return to dependent behavior raises interesting questions about other paths to sustained abstinence and recovery. Current emphasis on treatment outcome studies provides a means for researching factors in both those who recover with and without the assistance of self-help/mutual-help groups. The authors suggest some questions which might be investigated.     

Crohn's disease and ulcerative colitis mucosal T cells are stimulated by intestinal epithelial cells: implications for immunosuppressive therapy

BACKGROUND: Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases, and their pathogenesis is attributed, in part, to alterations of the mucosal immune system. This study was designed to define the possible contribution of epithelial cells to the activation of lamina propria T lymphocytes (LPTs) in CD and UC. METHODS: LPTs isolated from CD, UC, and control surgical specimens were cocultured with freshly isolated allogeneic or autologous epithelial cells or epithelial cell lines. Resulting T-cell proliferation was evaluated by tritiated thymidine incorporation on day 5. RESULTS: When intestinal epithelial cells were used to stimulate mucosal T-cell proliferation, CD and UC LPTs were less responsive than control LPTs (p < 0.05 and p < 0.03, respectively). This difference between inflamed and control T cells was consistently observed by using a variety of different intestinal epithelial cell types. CONCLUSIONS: CD and UC mucosal T cells are hyporesponsive to activation by intestinal epithelial cells when compared with control LPTs. Elucidating the mechanism underlying the differential activation of CD and UC LPTs may help to better understand the immunopathogenesis of these conditions.