We report the first atomistic calculation of the saddle-point configuration and activation energy for the nucleation of a 3D dislocation loop from a stressed crack tip in single crystal Cu. The transition state is found using reaction pathway sampling schemes, the nudged elastic band, and dimer methods. For the (111)[110] crack, loaded typically at 75% of the athermal critical strain energy rel...

This paper presents a micromechanics-based elastoplastic damage model for quasi-brittle rocks in compression stress state. The plastic strain is considered to be related to frictional sliding along microcracks and inherently coupled with damage evolution. By following a homogenization procedure, we first determine the free energy for the matrix-cracks system. The thermodynamic force associated ...

combination formulations of liposomes with collagen have been previously introduced as a means of obtaining more stable and less permeable liposomes. in this study, the effect of aqueous solutions of the collagen products collapur? (col) and collapuron-dak? (cold) from henkle co., on the release rate of sodium chromate (chr) as a water-soluble model drug from stable plurilamellar vesicles (splv...

gel dosage forms are successfully used as drug delivery systems considering their ability to control drug release and to protect medicaments from a hostile environment. the aim of this work was to investigate the properties of carbopol 934p polymeric system in water-misible cosolvents such as glycerin and alcohol. benzocaine is a local anesthetic and the mucosal gel formulation is applied in th...

Kienzler and Hernnan recently showed that good and remarkably simple approximations of the stress intensity factors of cracks in beams can be obtained by bending theory estimations of the strain energy release as the crack is widened into a band of finite width. Their method has been based on equating this energy release to the energy release rate due to crack length extension, which has been p...

In Streptococcus pneumoniae expression of pyruvate oxidase (SpxB) peaks during the early growth phase, coincident with the time of natural competence. This study investigated whether SpxB influences parameters of competence, such as spontaneous transformation frequency, expression of competence genes, and DNA release. Knockout of the spxB gene in strain D39 abolished spontaneous transformation ...

Free-standing nanomembranes are two-dimensional materials with nanometer thickness but can have macroscopic lateral dimensions. We develop a fracture model to evaluate a pre-stretched free standing circular ultrathin nanomembrane and establish a relation between the energy release rate of a circumferential interface crack and the pre-strain in the membrane. Our results demonstrate that detachme...

In this research, optimization process of axisymmetric extrusion dies is proposed. Plastic zone is analyzed using finite element method in the Eulerian system with flow formulation. The die profiles are defined by Bezier curves with six control points. Two effective functions are considered in this research; standard deviation of the strain rate and the rate of energy consumption during extrusi...