Unfolding mechanism and free energy landscape of single, stable, alpha helices at low pull speeds.

Single alpha helices (SAHs) stable in isolated form are often found in motor proteins where they bridge functional domains. Understanding the mechanical response of SAHs is thus critical to understand their function. The quasi-static force-extension relation of a small number of SAHs is known from single-molecule experiments.

Tissue Damage, Temperature, and pH Induced by Different Electrode Arrays on Potato Pieces ( L.).

One of the most challenging problems of electrochemical therapy is the design and selection of suitable electrode array for cancer. The aim is to determine how two-dimensional spatial patterns of tissue damage, temperature, and pH induced in pieces of potato ( L., var.

Is cancer a pure growth curve or does it follow a kinetics of dynamical structural transformation?

Background: Unperturbed tumor growth kinetics is one of the more studied cancer topics; however, it is poorly understood. Mathematical modeling is a useful tool to elucidate new mechanisms involved in tumor growth kinetics, which can be relevant to understand cancer genesis and select the most suitable treatment.

Methods: The classical Kolmogorov-Johnson-Mehl-Avrami as well as the modified Kolmogorov-Johnson-Mehl-Avrami models to describe unperturbed fibrosarcoma Sa-37 tumor growth are used and compared with the Gompertz modified and Logistic models.

Role of the central cations in the mechanical unfolding of DNA and RNA G-quadruplexes.

Cations are known to mediate diverse interactions in nucleic acids duplexes but they are critical in the arrangement of four-stranded structures. Here, we use all-atom molecular dynamics simulations with explicit solvent to analyse the mechanical unfolding of representative intramolecular G-quadruplex structures: a parallel, a hybrid and an antiparallel DNA and a parallel RNA, in the presence of stabilising cations. We confirm the stability of these conformations in the presence of [Formula: see text] central ions and observe distortions from the tetrad topology in their absence.

DNA overstretching transition induced by melting in a dynamical mesoscopic model.

We present a phenomenological dynamical model describing the force induced melting as responsible for the DNA overstretching transition. The denaturation mechanism is developed under the framework of the mesoscopic one-dimensional Peyrard-Bishop-Dauxois (PBD) picture which models the melting features of a polymer chain by means of a Morse potential and the stacking interaction. We find a good agreement with both the experimental overstretching curve and the asymmetric hysteretic properties with different simulation times.

3D Stationary electric current density in a spherical tumor treated with low direct current: an analytical solution.

Electrotherapy with direct current delivered through implanted electrodes is used for local control of solid tumors in both preclinical and clinical studies. The aim of this research is to develop a solution method for obtaining a three-dimensional analytical expression for potential and electric current density as functions of direct electric current intensity, differences in conductivities between the tumor and the surrounding healthy tissue, and length, number and polarity of electrodes. The influence of these parameters on electric current density in both media is analyzed.