Black hole solutions to Einstein-Bel-Robinson gravity

By employing a combination of perturbative analytic methods, we study the physical properties of a static-spherically symmetric black hole in the framework of the recently proposed Einstien-Bel-Robinson version of gravity. We show that interestingly the theory propagates a transverse and massive graviton on a maximally symmetric background with positive energy. There is also a single ghost-free branch that returns to the Einstein case when \beta\to 0. Then, we obtain the conserved charges of the theory to study the thermodynamics of the black hole solutions. We get the thermodynamical quantities and show that the solutions undergo a first-order phase transition with associated Van der Waals behavior. We analyze the specific heat, determining that the black holes are thermodynamically stable over large regions of parametric space.Comment: 16 pages, 5 figure

Effect of nanosilver particles on hatchability of rainbow trout (Oncorhynchus mykiss) egg and survival of the produced larvae

Effect of nanosilver particles was studied on the hatchability of rainbow trout (Oncorhynchus mykiss) egg and survival of the produced larvae at about 12ºC. In the first experiment the water-based nanosilver particles was used at concentrations of 0.5, 1, 2 and 4 mgL^-1 for 30 minutes per day starting 24 hour post egg incubation until the hatching time. The mean percentage of hatchability reached in 27.6±0.2, 38.2±0.1, 41.6±0.4 and 48.6±1.5 in troughs treated with 0.5, 1, 2 and 4 mgL^-1 nanocid, respectively compared with 64.7±0.2 % for trough treated with malachite green at 2 mgL^-1 as positive control (P0.05). These data suggest a possible application of nanosilver particles in aquaculture sector particularly using incubator troughs of trout containing nanosilver materials

Time-resolved terahertz–Raman spectroscopy reveals that cations and anions distinctly modify intermolecular interactions of water

The solvation of ions changes the physical, chemical and thermodynamic properties of water, and the microscopic origin of this behaviour is believed to be ion-induced perturbation of water’s hydrogen-bonding network. Here we provide microscopic insights into this process by monitoring the dissipation of energy in salt solutions using time-resolved terahertz–Raman spectroscopy. We resonantly drive the low-frequency rotational dynamics of water molecules using intense terahertz pulses and probe the Raman response of their intermolecular translational motions. We find that the intermolecular rotational-to-translational energy transfer is enhanced by highly charged cations and is drastically reduced by highly charged anions, scaling with the ion surface charge density and ion concentration. Our molecular dynamics simulations reveal that the water–water hydrogen-bond strength between the first and second solvation shells of cations increases, while it decreases around anions. The opposite effects of cations and anions on the intermolecular interactions of water resemble the effects of ions on the stabilization and denaturation of proteins

Insight into nano-chemical enhanced oil recovery from carbonate reservoirs using environmentally friendly nanomaterials

The use of nanoparticles (NPs) in enhanced oil recovery (EOR) processes is very effective in reducing the interfacial tension (IFT) and surface tension (ST) and altering the wettability of reservoir rocks. The main purpose of this study was to use the newly synthesized nanocomposites (KCl / SiO2 / Xanthan NCs) in EOR applications. Several analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were applied to confirm the validity of the synthesized NCs. From the synthesized NCs, nanofluids were prepared at different concentrations of 100-2000 ppm and characterized using electrical conductivity, IFT, and ST measurements. From the obtained results, it can be observed that 1000 ppm is the optimal concentration of the synthesized NCs that had the best performance in EOR applications. The nanofluid with 1000 ppm KCl / SiO2 / Xanthan NCs enabled reducing the IFT and ST from 33 and 70 to 29 and 40 mN/m, respectively. However, the contact angle was highly decreased under the influence of the same nanofluid to 41° and the oil recovery improved by an extra 17.05 % OOIP. To sum up, KCl / SiO2 / Xanthan NCs proved highly effective in altering the wettability of rocks from oil-wet to water-wet and increasing the cumulative oil production

Reconstructing f(R) model from Holographic DE: Using the observational evidence

We investigate the corresponding relation between $f(R)$ gravity and an interacting holographic dark energy. By obtaining conditions needed for some observational evidence such as, positive acceleration expansion of universe, crossing the phantom divide line and validity of thermodynamics second law in an interacting HDE model and corresponding it with $f(R)$ mode of gravity we find a viable $f(R)$ model which can explain the present universe. We also obtain the explicit evolutionary forms of the corresponding scalar field, potential and scale factor of universe.Comment: 11page. phys. Scr (2012