A nanometric cushion for enhancing scratch and wear resistance of hard films.

Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject of intense technological interest. The capability to modulate these surface properties while preserving both the bulk properties of the materials and a well-defined, constant chemical composition of the surface is particularly attractive.

A stiffness switch in human immunodeficiency virus.

After budding from the cell, human immunodeficiency virus (HIV) and other retrovirus particles undergo a maturation process that is required for their infectivity. During maturation, HIV particles undergo a significant internal morphological reorganization, changing from a roughly spherically symmetric immature particle with a thick protein shell to a mature particle with a thin protein shell and conical core. However, the physical principles underlying viral particle production, maturation, and entry into cells remain poorly understood.

Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy.

The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results of recent TM-specific mutation studies, suggests that it has an important role in the mechanism by which the cochlea transduces mechanical energy into neural excitation. A detailed characterization of TM mechanical properties is fundamental to understanding its role in cochlear mechanics.

Mechanical properties of murine leukemia virus particles: effect of maturation.

After budding from the host cell, retroviruses undergo a process of internal reorganization called maturation, which is prerequisite to infectivity. Viral maturation is accompanied by dramatic morphological changes, which are poorly understood in physical/mechanistic terms. Here, we study the mechanical properties of live mature and immature murine leukemia virus particles by indentation-type experiments conducted with an atomic force microscope tip.

Self-assembled peptide nanotubes are uniquely rigid bioinspired supramolecular structures.

We recently presented a novel class of self-assembled diphenylalanine-based peptide nanotubes. Here, for the first time, we present their mechanical properties, which we directly measured through indentation type experiments using atomic force microscopy. We find that the averaged point stiffness of the nanotubes is 160 N/m, and that they have a correspondingly high Young's modulus of approximately 19 GPa, as calculated by finite element analysis.