We describe how twist could play an essential role in stabilizing 20 nm diameter sickle hemoglobin fibers. Our theory successfully reproduces the observed variation of helical pitch length with fiber diameter. With no remaining adjustable parameters it also yields a prediction for the torsional rigidity of sickle hemoglobin fibers that is in good agreement with experiment and hence retains the ...

A theoretical study of the rigidities of slabs with circular voids oriented in the longitudinal and in the transverse direction is discussed. Equations are presented for predicting the bending and torsional rigidities of the voided slabs. This paper summarizes the results of an extensive literature search and initial review of the current methods of analyzing voided slab. The various methods of...

For every positive regular Borel measure, possibly infinite valued, vanishing on all sets of p-capacity zero, we characterize the compactness of the embedding W (R ) ∩ L(R , μ) ↪→ L(R ) in terms of the qualitative behavior of some characteristic PDE. This question is related to the well posedness of a class of geometric inequalities involving the torsional rigidity and the spectrum of the Diric...

A theory for the prediction of the size dependence of torsional rigidities of nanosized structural elements is developed. It is shown that, to a very good approximation, the torsional rigidity (D) of a nanosized bar differs from the prediction of standard continuum mechanics (Dc) as (D−Dc)/Dc = Ah0/a where A is a non-dimensional constant, a is the size scale of the cross-section of the bar and ...

We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds P with controlled radial mean curvature in ambient Riemannian manifolds N with a pole p and with sectional curvatures bounded from above and from below, respectively. These bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...

Genomic DNA is constantly subjected to various mechanical stresses arising from its biological functions and cell packaging. If the local mechanical properties of DNA change under torsional and tensional stress, the activity of DNA-modifying proteins and transcription factors can be affected and regulated allosterically. To check this possibility, appropriate steady forces and torques were appl...

The study of surface waves in a layered media has their viable application in geophysical prospecting. This paper presents an analytical study on the dispersion of torsional surface wave in a pre-stressed heterogeneous layer sandwiched between a pre-stressed anisotropic porous semi-infinite medium and gravitating anisotropic porous half-space. The non-homogeneity within the intermediate layer a...

latticed columns are frequently used in industrial steel structures. in some countries these built-up columns might be even used in other types of steel structures such as residential and commercial buildings. besides, latticed columns are parts of skeletons of many historic buildings all around the world. to analyze a steel structure with latticed columns a more accurate numerical model for su...

Carbon nanotubes (CNTs) are specific structures with valuable characteristics. In general, the structure of each nanotube is defined by a unique chiral vector. In this paper, different structures of short single-walled CNTs are simulated and their mechanical properties are determined using finite element method. For this aim, a simple algorithm is presented which is able to model the geometry o...