2,197 research outputs found
Engineering transport by concatenated maps
We present a generalized kick rotor model in which the phase of the kick can
vary from kick to kick. This additional freedom allows one to control the
transport in phase space. For a specific choice of kick-to-kick phases, we
predict novel forms of accelerator modes which are potentially of high
relevance for future experimental studies
The sign of the reaction volume for the water/silica reaction
In the present report, we deal with the question whether the equilibrium of the silica/water reaction shifts under tensile stresses to an increased or reduced hydroxyl concentration or equivalently, which sign the reaction volume shows. From our analysis on the basis of the Le Chatelier-Braun Theorem, it can be concluded that the equilibrium constant of the watersilica
reaction is enhanced due to tensile stresses and that the reaction volume change is positive. In additon it will be shown that the apparently found enlarged water solubility under compressive stresses by Nogami and Tomozawa [2] is an artifact of the stress-dependent diffusivity
Insulation for cryogenic tanks has reduced thickness and weight
Dual seal insulation, consisting of an inner layer of sealed-cell Mylar honeycomb core and an outer helium purge channel of fiber glass reinforced phenolic honeycomb core, is used as a thin, lightweight insulation for external surfaces of cryogenic-propellant tanks
Arthritis Is Developed in Borrelia-Primed And -Infected Mice Deficient of Interleukin-17
Interleukin-17 (IL-17) has been shown to participate in the development of Lyme arthritis in experimental mice. For example, neutralization of IL-17 with antibodies inhibits induction of arthritis in Borrelia-primed and -infected C57BL/6 wild-type mice. We hypothesized that mice lacking IL-17 would fail to develop Borrelia-induced arthritis. IL-17-deficient and wild-type C57BL/6 mice were primed with heat-inactivated Borrelia and then infected with viable spirochetes 3 weeks later. No swelling or major histopathological changes of the hind paws were detected in IL-17-deficient or wild-type mice that were primed with Borrelia or infected with viable spirochetes. By contrast, IL-17-deficient and wild-type mice that were primed and subsequently infected with heterologous Borrelia developed severe swelling and histopathological changes of the hind paws. In addition, Borrelia-primed and -infected IL-17-deficient mice exhibited elevated gamma-interferon (IFN-γ) levels in sera and increased frequencies of IFN-γ-expressing lymphocytes in popliteal lymph nodes compared to Borrelia-primed and -infected wild-type mice. These results demonstrate that IL-17 is not required for development of severe pathology in response to infection with Borrelia burgdorferi, but may contribute to disease through an interaction with IFN-γ
Stress-enhanced silica/water reaction under torsion loading
Water reacting with silica causes the generation of hydroxyl SiOH accompanied by a volume or swelling expansion. The principle of LeChatelier ensures that the hydroxyl concentration increases with increasing externally applied stresses. From the analysis in [1,2] it becomes obvious that
a) the hydroxyl concentration must depend on the multi-axiality of the
applied stresses, and
b) that the swelling effect is anisotropic.
On the basis of the results in [1,2] it will be shown that under torsion loading the strongest effects on stress-enhanced hydroxyl generation and swelling strains should occur, although this stress state shows a disappearing hydrostatic stress term
Effect of torsion loading on swelling in silica
Water reacting with silica causes the generation of hydroxyl SiOH accompanied by a volume or swelling expansion. The principle of LeChatelier ensures that the hydroxyl concentration increases with increasing externally applied stresses. From literature it becomes obvious that (a) the hydroxyl concentration must depend on the multi-axiality of the applied stresses, and (b) that the swelling effect is anisotropic. Based on Finite Element results it can be shown that for instance under torsion loading a strong stress-enhancement of the water/silica reaction with increased hydroxyl content must occur although this stress state shows a disappearing hydrostatic stress term. Due to the disappearing hydrostatic stress term under torsion loading, no mechanical effect would have been expected in torsion tests. Seen from this point of view, the torsion test seems ideal to us to provide evidence of anisotropic swelling. Further effects that can also influence the torsion test are addressed in the Appendix
- …