We report a study on particle diffusion in membranes formed from polystyrene-block-poly(2-(dimethylamino)ethyl methacrylate) (PS-b-PDMAEMA) diblock copolymers. The membranes were investigated by scanning electron microscopy and by single-particle tracking employing carboxy-functionalized polystyrene beads loaded with a fluorophore as spectroscopic probes. From the diffusion trajectories we extr...

In many cell-signaling pathways, information is transmitted by the diffusion of messenger molecules. Diffusion coefficients characterize the messenger's spatial range and the characteristic times of signal propagation. Inside cells, particles usually diffuse in the presence of immobile binding sites (or traps). It is well known that binding to traps results in an effective diffusion coefficient...

The dissolution kinetics of pandermite and hydroboracite, present in an Iranian borate ore, in sulfuric acid has been comparatively studied. The effect of particle size, temperature, and acid concentration on their dissolution rate was investigated. Dissolution rates of both minerals increased by reducing the particle size and by raising the temperature. Although, an increase in the acid concen...

Diffusion constants are typically considered to be independent of particle size with the benefit of nanosizing materials arising solely from shortened transport paths. We show that for materials with one-dimensional atomic migration channels, the diffusion constant depends on particle size with diffusion in bulk being much slower than in nanoparticles. This model accounts for conflicting data o...

A relativistic bounce-averaged quasilinear diffusion equation is derived to describe stochastic particle transport associated with arbitrary-frequency electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for the elements of a relativistic quasilinear diffusion tensor are calculated explicitly for magnetically-trapped particle distributions in axisymmetric magnetic geometr...

Time course measurement of single molecules on a cell surface provides detailed information on the dynamics of the molecules, which is otherwise inaccessible. To extract the quantitative information, single particle tracking (SPT) is typically performed. However, trajectories extracted by SPT inevitably have linking errors when the diffusion speed of single molecules is high compared to the sca...

Quantum dots of CdS with hexagonal phase were prepared at relatively low temperature (60 oC) and short time by micro-emulsion (O/W) under ultrasound. This study was focused on the particle size distribution and the growth kinetics. The particle size distribution obtained from the optical absorption edge. It was relatively symmetrical with sonication time. In addition, an agreement was observed ...

We consider a charged quantum particle in a random magnetic field with Gaussian, delta-correlated statistics. We show that although the single particle properties are peculiar, two particle quantities such as the diffusion constant can be calculated in perturbation theory. We map the problem onto a non-linear sigma-model for Q-matrices of unitary symmetry with renormal-ized diffusion coefficien...

objective(s) theophylline, a xanthenes derivative, is still widely used as an effective bronchodilator in the management of asthmatic patients. it is used both as a prophylactic drug and to prevent acute exacerbations of asthma. the aim of study was to formulate and evaluate effect of the microencapsulation of theophylline loaded nanoparticles on the reduction of burst release. materials and me...

Objective(s) Theophylline, a xanthenes derivative, is still widely used as an effective bronchodilator in the management of asthmatic patients. It is used both as a prophylactic drug and to prevent acute exacerbations of asthma. The aim of study was to formulate and evaluate effect of the microencapsulation of theophylline loaded nanoparticles on the reduction of burst release. Materials and Me...