Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userRoom temperature flashing Ratcheting in nano-channels
57
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We consider the surface-induced ratcheting transport of particles in nano-channels, particularly at room temperature. We show that at room temperature it is possible to achieve ratcheting of about 10 nm size particles in a nano-channel of about 100 nm width. The typical ratcheting velocity in such a case could be of the order of a few hundred nano-meter when the surface undulations are of a wavelength of a few hundred nano-meter and of the amplitude of a few tens of nano-meter. At room temperature, the viscosity of the fluid enabling such transport in the nano-channels comes out to be that of water. We show here a considerably large effect under realistic conditions which could be used for application in efficient filtration of particles and probably are in use in biological systems which typically work at room temperature.
rate research
Read More
Additive symmetric Levy noise can induce directed transport of overdamped particles in a static asymmetric potential. We study, numerically and analytically, the effect of an additional dichotomous random flashing in such Levy ratchet system. For this purpose we analyze and solve the corresponding fractional Fokker-Planck equations and we check the results with Langevin simulations. We study the behavior of the current as function of the stability index of the Levy noise, the noise intensity and the flashing parameters. We find that flashing allows both to enhance and diminish in a broad range the static Levy ratchet current, depending on the frequencies and asymmetry of the multiplicative dichotomous noise, and on the additive Levy noise parameters. Our results thus extend those for dichotomous flashing ratchets with Gaussian noise to the case of broadly distributed noises.
We consider a randomly flashing ratchet, where the potential acting can be switched to another at random. Using coupled Fokker-Planck equations, we formulate the expressions of quantities measuring dynamics and thermodynamics. Extended numerical calculations present how the potential landscapes and the transitions affect the motility and energetics. Load-dependent velocity and energetic efficiency of motor proteins, kinesin and dynein, further exemplify the randomly flashing ratchet model. We also discuss the system with two shifted sawtooth potentials.
We report heat pulse experiments at room temperature that cannot be described by Fouriers law. The experimental data is modelled properly by the Guyer--Krumhansl equation, in its over-diffusion regime. The phenomenon is due to conduction channels with differing conductivities, and parallel to the direction of the heat flux.
The analogy between magnetism and electricity has long been established by Maxwell in the 19th century, in spite of their subtle difference. While magnetic materials display paramagnetism, ferromagnetism, antiferromagnetism, and diamagnetism, only paraelectricity, ferroelectricity, and antiferrolelectricity have been found in dielectric materials. The missing `diaelectricity may be found if there exists a material that has a dc-polarization opposing the electric field or a negative dielectric susceptibility epsilon-1, with epsilon being the real part of the relative dielectric constant. Both of these properties have been observed in nano-particle aggregates under a dc electric bias field at room temperature. A possible collective effect in the nano-particle aggregates is proposed to account for the observation. `Diaelectricity implies overscreening by polarization to the external charges. Materials with a negative static epsilon are expected to provide attraction to similar charges and unusual scattering to electromagnetic waves with possible profound implications for high temperature superconductivity and communication.
To understand the non-exponential relaxation associated with solvation dynamics in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate, we study power spectra of the fluctuating Franck-Condon energy gap of a diatomic probe solute via molecular dynamics simulations. Results show 1/f dependence in a wide frequency range over 2 to 3 decades, indicating distributed relaxation times. We analyze the memory function and solvation time in the framework of the generalized Langevin equation using a simple model description for the power spectrum. It is found that the crossover frequency toward the white noise plateau is directly related to the time scale for the memory function and thus the solvation time. Specifically, the low crossover frequency observed in the ionic liquid leads to a slowly-decaying tail in its memory function and long solvation time. By contrast, acetonitrile characterized by a high crossover frequency and (near) absence of 1/f behavior in its power spectra shows fast relaxation of the memory function and single-exponential decay of solvation dynamics in the long-time regime.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
