Alternative models of cell mechanics depict the living cell as a simple mechanical continuum, porous filament gel, tensed cortical membrane, or tensegrity network that maintains a stabilizing prestress through incorporation of discrete structural elements that bear compression. Real-time microscopic analysis of cells containing GFP-labeled microtubules and associated mitochondria revealed that ...

Tobacco plants (Nicotiana rustica L.) pre-exposed to leaf dehydration, mineral deprivation, salination, or BO(3) (3-) toxicity exhibited increased resistance to subzero temperature and to reduced oxygen in the root medium. The stressed plants all showed an elevated content of leaf abscisic acid. Upon transfer of mineral deprived and salinated plants to prestress conditions, a decline in leaf ab...

In this study, fire resistance tests were performed on a conventional slim floor beam and a prestressed composite beam with corrugated webs, which is suitable for a long-span structure with a reduction in story height by utilizing the prestress and accordion effect. In the fire test program, the ISO 834 standard fire curve was adopted. Key test variables were the effect of prestress, shape of c...

Concrete has been prestressed traditionally with high-strength steel. The vulnerability of such material to corrosion calls for alternate materials, if thin-sheet products are to be prestressed. A research project at Columbia University is investigating the feasibility of using aramid fiber mesh for such purpose. This paper explores the chemical and mechanical properties of aramid in the form o...

The glassy wormlike chain model is a highly successful phenomenological model recently introduced to describe anomalously slow subdiffusive dynamics in biopolymer networks and living cells. Here we extend this model by proposing a generic scheme how to include nonlinear plastic effects by introducing the possibility of force-dependent opening and closing of internal bonds. Further, we discuss p...