DNA-binding small molecules are widespread in the cell and heavily used in biological applications. Here, we use magnetic tweezers, which control the force and torque applied to single DNAs, to study three small molecules: ethidium bromide (EtBr), a well-known intercalator; netropsin, a minor-groove binding anti-microbial drug; and topotecan, a clinically used anti-tumor drug. In the low-force ...

DNA and other biopolymers differ from classical polymers because of their torsional stiffness. This property changes the statistical character of their conformations under tension from a classical random walk to a problem we call the "torsional directed walk." Motivated by a recent experiment on single lambda-DNA molecules [Strick, T. R., Allemand, J.-F., Bensimon, D., Bensimon, A. & Croquette,...

We report measurements of the Casimir force between a gold sphere and a silicon surface with an array of nanoscale, rectangular corrugations using a micromechanical torsional oscillator. At distances between 150 and 500 nm, the measured force shows significant deviations from the pairwise additive formulism, demonstrating the strong dependence of the Casimir force on the shape of the interactin...

Curling of knitted fabrics edges is one of the complicated problems of these structures. Therefore, study and measurement of curling in knitted fabrics is important. In this study, it is tried to model the three-dimensional wale wise curl of the fabric using finite element modelling. In this model the tensions in different parts of a knitted loop due to bending and torsional forces in knitting ...

Theoretical and experimental evidence for non-linear hydrogen bonds in protein helices is ubiquitous. In particular, amide three-centered hydrogen bonds are common features of helices in high-resolution crystal structures of proteins. These high-resolution structures (1.0 to 1.5 Å nominal crystallographic resolution) position backbone atoms without significant bias from modeling constraints and...

Results on design, fabrication, and testing of silicon micromachined magnetic actuators are presented. Electroplated, low-stress permalloy (Ni80Fe20) material is the medium for magnetic interaction and force generation. The permalloy piece is supported by a structural plate, which consists of polycrystalline silicon thin film prepared by low-pressure chemical vapor deposition (LPCVD). Magnetic ...

BACKGROUND A continuous running suture is the preferential method for abdominal closure. In this technique the suture is secured with an initial knot and successive tissue bites are taken. At each tissue bite, the needle is rotated through the tissue; in doing so, the suture can twist around the knot which acts as an anchor. OBJECTIVE To determine the effect of axial torsional forces on sutur...