Fast and Accurate Numerical Integration of the Langevin Equation with Multiplicative Gaussian White Noise.

A univariate stochastic system driven by multiplicative Gaussian white noise is considered. The standard method for simulating its Langevin equation of motion involves incrementing the system's state variable by a biased Gaussian random number at each time step. It is shown that the efficiency of such simulations can be significantly enhanced by incorporating the skewness of the distribution of the updated state variable.

Limit Efficiency of a Silicon Betavoltaic Battery with Tritium Source.

An idealized design of a silicon betavoltaic battery with a tritium source is considered, in which a thin layer of tritiated silicon is sandwiched between two intrinsic silicon slabs of equal width, and the excess charge carriers are collected by thin interdigitated n and p electrodes. The opposite sides of the device are covered with a reflecting coating to trap the photons produced in radiative recombination events. Due to photon recycling, radiative recombination is almost ineffective, so the Auger mechanism dominates.

New PMMA-Based Hydroxyapatite/ZnFeO/ZnO Composite with Antibacterial Performance and Low Toxicity.

Polymethylmethacrylate (PMMA) is the most commonly used bone void filler in orthopedic surgery. However, the biocompatibility and radiopacity of PMMA are insufficient for such applications. In addition to insufficient biocompatibility, the microbial infection of medical implants is one of the frequent causes of failure in bone reconstruction.

Diffusion coefficient scaling of a free Brownian particle with velocity-dependent damping.

An analytical expression for the diffusion coefficient D of a free Brownian particle with velocity-dependent damping γ(v) is derived from the Green-Kubo formula. A special case of damping that decreases monotonically with velocity is considered. At high temperature T, the diffusion coefficient is found to exhibit two scaling types: (i) for a power-law decrease of damping with the particle's kinetic energy, γ(v)∝1/v^{2α}, it scales as D∝T^{α+1}; (ii) for a Gaussian function γ(v), it diverges at temperatures above a critical value T_{c} and behaves as D∝1/sqrt[T_{c}-T] at T slightly below T_{c}.

C Fullerene Clusters Stabilize the Biologically Inactive Form of Topotecan.

There is a range of experimental proofs that biologically relevant compounds change their activity in the presence of C fullerene clusters in aqueous solution, which most frequently act as a nanoplatform for drug delivery. Inspired by this evidence, we made an effort to investigate the interaction of fullerene clusters with the antibiotic topotecan (TPT). This study proceeded in three steps, namely, UV/vis titration to confirm complexation and in vitro assays on proliferating and nonproliferating cells to elucidate the role of C fullerene in the putative change in TPT activity.