We describe a technique for probing the elastic properties of biological membranes by using an atomic force microscope (AFM) tip to press the biological material into a groove in a solid surface. A simple model is developed to relate the applied force and observed depression distance to the elastic modulus of the material. A measurement on the proteinaceous sheath of the archaebacterium Methanospirillum hungatei GP1 gave a Young's modulus of 2 ؋ 10 10 to 4 ؋ 10 10 N/m 2 . The measurements suggested that the maximum sustainable tension in the sheath was 3.5 to 5 N/m. This finding implied a maximum possible internal pressure for the bacterium of between 300 and 400 atm. Since the cell membrane and S-layer (wall) which surround each cell should be freely permeable to methane and since we demonstrate that the sheath undergoes creep (expansion) with pressure increase, it is possible that the sheath acts as a pressure regulator by stretching, allowing the gas to escape only after a certain pressure is reached. This creep would increase the permeability of the sheath to diffusible substances.
Highly crystalline LixMoS2 was synthesized, and the lithium content was electrochemically varied between x ~ 0 and x ~ 1. There were five different phases each with a different lithium content. The crystal lattices had small triclinic or monoclinic distortions from 1T-hexagonal symmetry. These discoveries contradict claims in the literature that crystalline MoS2 disproportionates when the lithium content exceeds 0.2.
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