A novel method is presented for fitting force-field dihedral angles using an ensemble of structures generated from an ab initio Monte Carlo simulation. Importance sampling is used to achieve an efficient algorithm using a low level of theory to minimize the system at each step with the dihedral angles constrained, followed by dihedral fitting using the single point energies at a higher level of...

Two methods commonly used to measure the normal spring constants of atomic force microscope cantilevers are the added mass method of Cleveland et al. @J. P. Cleveland et al., Rev. Sci. Instrum. 64, 403 ~1993!#, and the unloaded resonance technique of Sader et al. @J. E. Sader, J. W. M. Chon, and P. Mulvaney, Rev. Sci. Instrum. 70, 3967 ~1999!#. The added mass method involves measuring the chang...

Understanding the mechanism of charge generation, distribution, and transfer between surfaces is very important for energy harvesting applications based on triboelectric effect. Here, we demonstrate dynamic nanotriboelectrification with torsional resonance (TR) mode atomic force microscopy (AFM). Experiments on rubbing the sample surface using TR mode for the generation of triboelectric charges...

The simple model of the non-linear DNA dynamics [4] is pursued in order to study the local untwisting of DNA double helix. It is shown how the advancing RNA polymerase may force the motion of the torsional solitary wave along DNA.

We report on the characterization of nanometer-scale torsional devices based on individual single-walled carbon nanotubes as the spring elements. The axial shear moduli of the nanotubes are obtained through modeling of device reaction to various amounts of applied electrostatic force and are compared to theoretical values.

In this study, we present conformational energies for a molecular mechanical model (Parm99) developed for organic and biological molecules using the restrained electrostatic potential (RESP) approach to derive the partial charges. This approach uses the simple “generic” force field model (Parm94), and attempts to add a minimal number of extra Fourier components to the torsional energies, but do...

Nic Mullin, Cvetelin Vasilev, Jaimey D. Tucker, C. Neil Hunter, Christa H. M. Weber, and Jamie K. Hobbs Department of Physics and Astronomy, University of Sheffield, The Hicks Building, Hounsfield Road, Sheffield, South Yorkshire S3 7RH, United Kingdom Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire S10 2TN, Unite...

The article shows the effect of torsional rigidity of beam elements onto spatial work of bridges, floorings and other plate-ribbed systems It is shown that, in determining the torsional rigidity using existing methods it is necessary to have spatial spiral cracks, but torsional rigidity when normal cracks is not researched. A method is described for determining the torsional rigidity of reinfor...