Late time cosmological approach in mimetic f(R,T)f(R,T) gravity

In this paper, we investigate the late-time cosmic acceleration in mimetic $f(R,T)$ gravity with Lagrange multiplier and potential in a Universe containing, besides radiation and dark energy, a self-interacting (collisional) matter. We obtain through the modified Friedmann equations, the main equation that can describe the cosmological evolution and with several models from $Q(z)$ and the well known particular model $f(R, T)$, we perform an analysis of the late-time evolution. We examine the behavior of the Hubble parameter, the dark energy equation of state and the total effective equation of state and we compare in each case the resulting picture with the non-collisional matter (assumed as dust) and also with the collisional matter in mimetic $f(R, T)$ gravity. The results obtained are in good agreement with the observational data and show that in presence of the collisional matter the dark energy oscillations in mimetic f(R, T) gravity can be damped.Comment: 18 pages, 2 figure

Fluence Threshold for Photothermal Bubble Generation Using Plasmonic Nanoparticles

International audienceUnder nano- to femtosecond pulsed illumination at their plasmonic resonance wavelength, metalnanoparticles efficiently absorb the incident light energy that is subsequently converted into heat. In aliquid environment, with sufficiently high pulse fluences (light energy per unit area), this heat generationmay result in the local formation of a transient nanobubble. This phenomenon has been the subjectof a decade of investigations and is at the basis of numerous applications from cancer therapy to photoacouticimaging. The aim of this article is to clarify the question of the fluence threshold requiredfor bubble formation. Using a Runge-Kutta-4 numerical algorithm modeling the heat diffusion arounda spherical gold nanoparticle, we numerically investigate the influence of the nanoparticle diameter,pulse duration (from the femto- to the nanosecond range), wavelength and Kapitza resistivity in orderto explain the observations reported in the literature

Late time cosmological approach in mimetic f(R,T)f(R,T) gravity

In this paper, we investigate the late-time cosmic acceleration in mimetic $f(R,T)$ gravity with Lagrange multiplier and potential in a Universe containing, besides radiation and dark energy, a self-interacting (collisional) matter. We obtain through the modified Friedmann equations, the main equation that can describe the cosmological evolution and with several models from $Q(z)$ and the well known particular model $f(R, T)$, we perform an analysis of the late-time evolution. We examine the behavior of the Hubble parameter, the dark energy equation of state and the total effective equation of state and we compare in each case the resulting picture with the non-collisional matter (assumed as dust) and also with the collisional matter in mimetic $f(R, T)$ gravity. The results obtained are in good agreement with the observational data and show that in presence of the collisional matter the dark energy oscillations in mimetic f(R, T) gravity can be damped.Comment: 18 pages, 2 figure

Controlled modification of optical and structural properties of glass with embedded silver nanoparticles by nanosecond pulsed laser irradiation

Glass with embedded spherical silver nanoparticles of ~15 nm in radius contained in a layer with thickness of ~20 µm was irradiated using a nanosecond (36 ns) pulsed laser at 532 nm. Laser irradiation led to the formation of a thin surface film containing uniformly distributed nanoparticles - with an increase in the overall average nanoparticle size. Increasing the applied number of pulses to the sample resulted in the increase of the average size of the nanoparticles from 15 nm to 35 – 70 nm in radius, and narrowing of the surface plasmon band compared to the absorption spectra of the original glass sample. The influence of the applied number of laser pulses on the optical and structural properties of such a recipient nanocomposite was investigated