Aging and Lifetimes Milestone 7777, G.C. #4: Assess the ability of MRI to identify chemical and mechanical heterogeneity in polymers at various length scales.

Morphogenesis is governed by the interplay of molecular signals and mechanical forces across multiple length scales. The last decade has seen tremendous advances in our understanding of the dynamics of protein localization and turnover at sub-cellular length scales, and at the other end of the spectrum, of mechanics at tissue-level length scales. Integrating the two remains a challenge, however, because we lack a detailed understanding of the subcellular patterns of mechanical properties of cells within tissues. Here, in the context of the elongating body axis of Xenopus embryos, we combine tools from cell biology and physics to demonstrate that individual cell-cell junctions display finely-patterned local mechanical heterogeneity along their length. We show that such local mechanical patterning is essential for the cell movements of convergent extension and is imparted by locally patterned clustering of a classical cadherin. Finally, the patterning of cadherins and thus local mechanics along cell-cell junctions are controlled by Planar Cell Polarity signaling, a key genetic module for CE that is mutated in diverse human birth defects.

Download Full-text

Mechanical heterogeneity along single cell-cell junctions is driven by lateral clustering of cadherins during vertebrate axis elongation

10.1101/2020.02.11.944033 ◽

2020 ◽

Cited By ~ 1

Author(s):

Robert J. Huebner ◽

Abdul Naseer Malmi-Kakkada ◽

Sena Sarikaya ◽

Shinuo Weng ◽

D. Thirumalai ◽

...

Keyword(s):

Cell Biology ◽

Planar Cell Polarity ◽

Protein Localization ◽

Tissue Level ◽

Cell Junctions ◽

Convergent Extension ◽

Length Scales ◽

Mechanical Heterogeneity ◽

Multiple Length Scales ◽

Cell Cell

AbstractMorphogenesis is governed by the interplay of molecular signals and mechanical forces across multiple length scales. The last decade has seen tremendous advances in our understanding of the dynamics of protein localization and turnover at sub-cellular length scales, and at the other end of the spectrum, of mechanics at tissue-level length scales. Integrating the two remains a challenge, however, because we lack a detailed understanding of the subcellular patterns of mechanical properties of cells within tissues. Here, in the context of the elongating body axis of a vertebrate embryo, we combine tools from cell biology and physics to demonstrate that individual cell-cell junctions display finely-patterned local mechanical heterogeneity along their length. We show that such local mechanical patterning is essential for the cell movements of convergent extension and is imparted by locally patterned clustering of a classical cadherin. Finally, the patterning of cadherins and thus local mechanics along cell-cell junctions are controlled by Planar Cell Polarity signaling, a key genetic module for CE that is mutated in diverse human birth defects.

Download Full-text

MODELING THE EFFECTIVE DYNAMIC PROPERTIES OF FIBER COMPOSITES MODIFIED ACROSS LENGTH SCALES

Nanoscience and Technology An International Journal ◽

10.1615/nanoscitechnolintj.2018026537 ◽

2018 ◽

Vol 9 (2) ◽

pp. 117-138 ◽

Cited By ~ 2

Author(s):

Dmitriy B. Volkov-Bogorodsky ◽

Sergey A. Lurie ◽

G. I. Kriven

Keyword(s):

Dynamic Properties ◽

Fiber Composites ◽

Length Scales ◽

Effective Dynamic

Download Full-text

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

Tire Science and Technology ◽

10.2346/1945-5852-40.2.124 ◽

2012 ◽

Vol 40 (2) ◽

pp. 124-150

Author(s):

Klaus Wiese ◽

Thiemo M. Kessel ◽

Reinhard Mundl ◽

Burkhard Wies

Keyword(s):

Coefficient Of Friction ◽

Liquid Layer ◽

Contact Area ◽

Leading Edge ◽

Viscous Friction ◽

Analytical Approximation ◽

Real Contact Area ◽

Length Scales ◽

Real Contact ◽

Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

Download Full-text