Interaction between uracil nucleobase and phenylalanine amino acid: the role of sodium cation in stacking

The stacking interactions in the uracil:phenylalanine (U:PHE) and (U:PHE)···Na⁺ complexes have been studied at different levels of theory, in which the structures were optimized by both standard and gradient counterpoise corrected methods. The Na⁺ cation can interact with different sites of stacked U:PHE unit. The geometrical parameters of the optimized structures and the calculated binding energies reveal the influence of cation interaction on π–π stacking and vice versa. The interplay between π–π stacking and cation interaction has also been investigated by topological analysis of electron charge density using atoms in molecules (AIM) method. A good agreement between the results of AIM analysis and calculated binding energies has been observed in dimer and complexes.     

Essentiality and injectivity relative to sequential purity of acts

For a class ℳ of monomorphisms of a category, mathematicians consider different types of essentiality, depending on ℳ. In this paper, considering the category of acts over a semigroup, we first briefly study the class ℳ _p of a certain kind of pure monomorphisms, in a manner borrowed from V. Gould, to be called sequentially pure. Then, we study in detail three kinds of essentiality with respect to this class, and give some useful criteria to get (internal) characterizations (in terms of elements) for essentialities. Finally, the relations between injectivity, essentiality, retractness, and injective hulls, all with respect to the class of sequentially pure monomorphisms, are investigated. The second author is thankful to Iran National Science Foundation (INSF) for their financial support.     

Magnetic properties of strontium hexaferrite films prepared by pulsed laser deposition

The magnetic properties of strontium hexaferrite (SrFe₁₂O₁₉) films fabricated by pulsed laser deposition on the Si(100) substrate with Pt(111) underlayer have been studied as a function of film thickness (50–700 nm). X-ray diffraction patterns confirm that the films have c-axis perpendicular orientation. The coercivities in perpendicular direction are higher than those for in-plane direction which indicates the films have perpendicular magnetic anisotropy. The coercivity was found to decrease with increasing of thickness, due to the increasing of the grain size and relaxation in lattice strain. The 200 nm thick film exhibits hexagonal shape grains of 150 nm and optimum magnetic properties of M_s=298 emu/cm³ and H_c=2540 Oe.     

Can Inflation, Dark Matter and Dark Energy Be Described in Terms of a Single, Real Scalar Field?

In this article, our aim is to consider inflation, dark energy and dark matter in the framework of a real scalar field. To this end, we use the quintessence approach. We have tried a real scalar field with a specific self-interaction potential in a spacially flat universe. Numerical results indicate that this potential can drive the expansion of the universe in three distinct phases. The first phase behaves as an inflationary expansion. For this stage, setting the scalar field’s initial value to ϕ ₀≥1.94 leads to N 3 68\mathcal{N}\geq 68 favored by observation. After the inflationary phase, the scalar field starts an oscillatory behavior which averages to a =0\bar{w}=0 fluid. This stage can be taken as a cold dark matter (p≈0) epoch expected from works on the structure formation issue. Observations and cosmological models indicate that t _inf ≈10⁻³⁵ s and the matter dominated lasts for t _m ≈10¹⁷ s, hence (\fract_mt_inf)_obs ? 10⁵²(\frac{t_{m}}{t_{inf}})_{obs}\approx10^{52}. We have shown that the present model can satisfy such a constraint. Finally, the scalar field leaves the oscillatory behavior and once again enters a second inflationary stage which can be identified with the recent accelerated expansion of the universe. We have also compared our model with the ΛCDM model and have found a very good agreement between the equation of state parameter of both of models during the DM and DE era.     

Introduction of a new dichlorophen electrochemical sensor relying on the modified glassy carbon electrode (GCE) with carboxyl-functionalized graphene oxide/poly (L-arginine)

Journal of Solid State Electrochemistry - Dichlorophen (Dcp), a harmful environmental pollutant, is broadly utilized in veterinary medications, chemical fertilizers, pesticides, cosmetics, and...