Mass renormalization and runaway solutions

Zeitschrift für Physik B Condensed Matter - The relationship between negative mechanical mass and runaway solutions is studied using the model of a charged spherical shell. The model yields...     

Effect of process parameters on the mechanical properties of carbon nitride thin films synthesized by plasma assisted pulsed laser deposition

We present an investigation of the effect of the process parameters, namely deposition pressure and laser intensity, on the growth and mechanical properties of carbon nitride (CN_x) thin films synthesized by plasma assisted pulsed laser deposition. Deposition at high remote plasma pressure (200 mTorr) enhances both growth rate and nitrogen incorporation (up to 40 at.%), but nano-indentation measurements indicate that these films are very soft and have poor mechanical properties. At low remote plasma pressure (0.5 mTorr), the nitrogen content varies from 24 to 16 at.% with increasing laser intensity as the films become much harder and more elastic, with hardness and Youngs modulus values reaching 24 GPa and 230 GPa, respectively. These effects are explained in terms of a thermalization of the laser plasma at 200 mTorr and indicate that plasma activation of nitrogen does not provide any particular benefit to the film properties when deposition is performed at high pressure. However, at low pressure, the benefit of plasma activation is evidenced through enhanced nitrogen incorporation in the films while preserving the highly energetic species in the ablation plume. Such conditions lead to the synthesis, at room temperature, of hard and elastic films having properties close to those of fullerene-like CN_x. PACS 81.15.Fg; 81.05.Gc; 68.60.Bs     

Critical-point phase separation in laser ablation of conductors

Laser ablation due to an ultrashort laser pulse on a massive aluminum target was investigated by means of a one-dimensional fluid code. Clear separation between the ablated matter and the unablated target is seen to occur through spinodal decomposition involving thermodynamic instabilities near the critical point of aluminum. The code also shows that the end of the ablation process is preceded by the ejection of droplets, which form about 15% of the total ejected mass.     

Form factors,branching ratio and forward–backward asymmetry in B→K<Subscript>1</Subscript>ℓ<Superscript>+</Superscript>ℓ<Superscript>-</Superscript> decays

We study long-distance effects in the rare exclusive semileptonic decays B→K₁ℓ⁺ℓ^-, where K₁ is the axial vector meson. The form factors describing the meson transition amplitudes of the effective Hamiltonian are calculated using the Ward identities, which are then used to calculate the branching ratio and the forward–backward asymmetry in these decay modes. The zero of the forward–backward asymmetry is of special interest and provides us with a precision test of the standard model.     

A note on the second problem of Stokes for Maxwell fluids

New exact solutions corresponding to the second problem of Stokes for Maxwell fluids have been established by means of Laplace transforms. For large times, these solutions reduce to the well-known steady-state solutions which are periodic in time and independent of the initial conditions. Furthermore, the transient solutions are in accordance with the previous solutions obtained using the Fourier sine transform. The required time to get the steady-state is determined by graphical illustrations. This time decreases if the frequency of the velocity increases. The effects of the material parameters on the decay of the transients in time are also investigated by graphs.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.     

Statefinder diagnostic and stability of modified gravity consistent with holographic and agegraphic dark energy

Recently one of us derived the action of modified gravity consistent with the holographic and new-agegraphic dark energy. In this paper, we investigate the stability of the Lagrangians of the modified gravity as discussed in (Setare in Int J Mod Phys D 17:2219, 2008; Setare in Astrophys Space Sci 326:27, 2010). We also calculate the statefinder parameters which classify our dark energy model.     

Restoring New Agegraphic Dark Energy in RS II Braneworld

Motivated by recent works (Saridakis in Phys. Lett. B 660:138, 2008; Sheykhi in Int. J. Mod. Phys. D 19(3):305, 2010), we investigate the new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of variable gravitational constant G in our model. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the new agegraphic dark energy model in RS II braneworld cosmology including varying G.