, Phys. Rev. Lett. 108, 228105 (2012)], which have been difficult to validate due to the lack of direct experimental data. Furthermore, the model calculation shows that as the channel size passes below approximately 100 nm (or roughly the HSP990 solubility dmso Kuhn length of DNA) there is a dramatic drop in the relaxation time. Inasmuch as the chain friction rises with decreasing channel size, the reduction in the relaxation time can be solely attributed

to the sharp decline in the fluctuations of the chain extension. Practically, the low variance in the observed DNA extension in such small channels has important implications for genome mapping. (C) 2013 AIP Publishing LLC.”
“Based on ab initio total energy calculations, the diffusion mechanisms of group-III elements (B, Al, Ga, and In) in ZnO are investigated. The activation energy of vacancy-assisted mechanism consists of formation energy of

Zn vacancy (V-Zn), binding energy between the dopants and V-Zn, as well as effective diffusion energy barrier of the dopants in ZnO. The effective diffusion energy barriers of B, Al, Ga, and In are estimated to be 1.12, 1.76, 1.45, and 1.06 eV for in-plane diffusion, and 1.12, 2.19, 1.80, and 1.06 eV for out-of-plane selleck chemicals llc diffusion, respectively. The binding energies are estimated to be -0.66, -0.52, -0.48, and -0.43 eV for B-, Al-, Ga-, and In-V-Zn pairs, showing a size decreasing behavior. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3103307]“
“Computational fluid dynamic (CFD) simulation is a powerful tool in the design and implementation of microfluidic systems, especially for systems that involve hydrodynamic behavior of objects such as functionalized microspheres, biological cells, or biopolymers in complex structures. In this work, we investigate hydrodynamic trapping of microspheres in a novel microfluidic particle-trap array device by finite element simulations. The accuracy of the time-dependent simulation of a microsphere’s find more motion towards the traps is validated by our experimental

results. Based on the simulation, we study the fluid velocity field, pressure field, and force and stress on the microsphere in the device. We further explore the trap array’s geometric parameters and critical fluid velocity, which affect the microsphere’s hydrodynamic trapping. The information is valuable for designing microfluidic devices and guiding experimental operation. Besides, we provide guidelines on the simulation set-up and release an openly available implementation of our simulation in one of the popular FEM softwares, COMSOL Multiphysics. Researchers may tailor the model to simulate similar microfluidic systems that may accommodate a variety of structured particles. Therefore, the simulation will be of particular interest to biomedical research involving cell or bead transport and migration, blood flow within microvessels, and drug delivery. (C) 2013 AIP Publishing LLC.