جستجوی مقالات مرتبط با کلیدواژه "transport properties" در نشریات گروه "شیمی"

In this paper, the validity of Stokes-Einstein (SE) equation for estimating the transport properties (e.g. viscosity) of imidazolium-based ionic liquids [Cnmim]Br (n=2,4,5,6) was examined. In order to achieve this goal, the “hole theory” has been utilized for estimating the mean radius of hole. According to the hole theory formalism, the mean radius of hole is related to surface tension. To do so, the Fowler recipe of Kirkwood-Buff (FKB) equation is implemented the calculation of Lennard-Jones's contribution to surface tension of ILs. In the following, assessment of the SE equation is depicted by drawing of  versus . Our test confirms the linearity of diagram and then verifies the validity of the aforementioned approach. The results show that within the imidazolium family, as the cation alkyl chain length increases due to the increased Coulombic forces between the cation and the anion, surface tension decreases.

Sodium dodecyl sulfate (SDS) solution is considered a cell membrane mimicking solution. In this study, the effect of the amyloid-beta peptide on the structure and diffusion coefficient of SDS was investigated by molecular dynamics simulation. To control the accuracy of the calculations, a micelle containing 60 molecules of SDS was simulated. The radius of gyration and the moment of inertia of the micelle were calculated and compared with the experimental and simulation results. The results obtained were in good agreement with the experimental and simulation results. The simulations in the presence of amyloid-beta were performed at two concentrations of SDS, below and above the critical micelle concentration. The results showed that as the concentration of SDS increased, the diffusion coefficient of peptide and sodium ion increased while the diffusion coefficient of water and SDS decreased. The calculation of the moments of inertia in different directions showed that the micelles deviated from the ellipsoidal shape at sub-critical micelle concentrations of SDS.

In this study the intermolecular potential energies of some environment-friendly industrial HFC refrigerants were obtained through the inversion method which is based on the corresponding states principle. These potentials were later employed in calculation of transport properties (viscosity, diffusion, thermal conductivity and thermal diffusion factor) of some binary and ternary refrigerant mixtures, in the low density region. Predicted transport properties were compared with the available literature data and gave rise to the acceptable agreement. On the other hand, the interaction potential was fitted to an analytical form, and the calculated low density transport properties were also fitted to the fairly exact equations. In the case of R410A and R421B mixtures, high density viscosity values were also calculated through the Vesovic-Wakeham method. Due to lack of experimental values on high density viscosities of these two mixtures, we could only compare calculated high density viscosities for other available molar compositions of R124-R134a and R125-R32 binary mixtures, with literature data, while again acceptable accordance was observed.

Ion channels are naturally occurring pores through the proteins that regulate the passage of ions and thus maintain the concentration of ions inside and outside the cell. The ion channels control many physiological functions and they can show selectivity for a specific ion.Ion channels are mostly observed in nerve cells and muscle cells. The influx of ions into cells can be regulated by a gate, like voltage controlled gate. Here we have investigated the ion transport through an ion channel by Poisson-Nernst-Plank model. In this model, proteins are approximated as cylindrical tubes embedded in a lipid membrane. Different ion channels with different channel radii are taken into consideration. The electrostatic potential, ion concentrations, ion flux and ion current are found. Simulation of ion channel is of vital importance in preparing biosensor where the molecular switching mechanism of ion-channel can regulate the flow of a particular ion in an analyte, if detected. The ion channels show voltage-current relationship similar to that of diodes and transistors. A major challenge in nanomedicine is the quick detection of antigens causing a disease and thus the finding of a novel commercial technique (better than ELISA) is essential. Towards this aim, a nanobiosensor can be devised where an ion-channel may serve as its primary component.