Three-component synthesis and antibacterial evaluation of some novel 1,2-dihydroisoquinoline derivatives

Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of products make it an interesting process compared to other approaches. The compounds have been analyzed for antibacterial activity against Gram negative and Gram positive bacteria. The results indicated that 1,2-dihydroisoquinolines derived from kojic acid are effective against all of the studied bacteria especially against Bacillus subtilis, while the products obtained from8-hydroxyquinoline are active only against Gram positive bacteria.     

w d =−1 in interacting quintessence model

A model consisting of a quintessence scalar field interacting with cold dark matter is considered. The conditions required to reach w _d =?1 are discussed. It is shown that, depending on the potential considered for the quintessence, crossing the phantom divide line puts some constraints on the interaction between dark energy and dark matter. This also may determine the ratio of dark matter to dark energy density at w _d =?1.     

Experimental and thermodynamic modelling of systems containing water and ethylene glycol: Application to flow assurance and gas processing

Accurate knowledge of hydrate phase equilibrium in the presence of inhibitors is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. In this communication, we report new experimental dissociation data for various systems consisting of methane/water/ethylene glycol and natural gas/water/ethylene glycol. A statistical thermodynamic approach, with the Cubic-Plus-Association equation of state, is employed to model the phase equilibria. The hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The thermodynamic model was used to predict the hydrate dissociation conditions of methane and natural gases in the presence of distilled water or ethylene glycol aqueous solutions. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.     

Rational Design,Synthesis, and Optical Properties of Film‐Forming,Near‐Infrared Absorbing,and Fluorescent Chromophores with Multidonors and Large Heterocyclic Acceptors

A new series of film‐forming, low‐bandgap chromophores ( 1 a,b and 2 a,b ) were rationally designed with aid of a computational study, and then synthesized and characterized. To realize absorption and emission above the 1000 nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron‐donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27–0.71 eV, and accordingly absorb at 746–1003 nm and emit at 1035–1290 nm in solution. By design, the relatively high molecular weight (up to 2400 g mol^?1) and non‐coplanar structure allow these near‐infrared (NIR) chromophores to be readily spin‐coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]‐phenyl‐C₆₁ butyric acid methyl ester leads to a red shift in the absorption only for 1 a and 2 a . An interesting NIR electrochromism was found for 2 a , with absorption being turned on at 1034 nm when electrochemically switched (at 1000 mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256–318 nm) is also unique for this multidonor–acceptor type of chromophore, indicating a significant structural difference between the ground state and the excited state. Photoluminescence of the film of 2 a was further probed at variable temperatures and the results strongly suggest that the restriction of bond rotations certainly helps to diminish non‐radiative decay and thus enhance the luminescence of these large chromophores.     

Stability of circular orbits of spinning particles in Schwarzschild-like space–times

Circular orbits of spinning test particles and their stability in Schwarzschild-like backgrounds are investigated. For these space–times the equations of motion admit solutions representing circular orbits with particles spins being constant and normal to the plane of orbits. For the de Sitter background the orbits are always stable with particle velocity and momentum being co-linear along them. The world-line deviation equations for particles of the same spin-to-mass ratios are solved and the resulting deviation vectors are used to study the stability of orbits. It is shown that the orbits are stable against radial perturbations. The general criterion for stability against normal perturbations is obtained. Explicit calculations are performed in the case of the Schwarzschild space–time leading to the conclusion that the orbits are stable.     

Spinning fluid cosmology

The dynamics of a spinning fluid in a flat cosmological model is investigated. The space–time is itself generated by the spinning fluid which is characterized by an energy–momentum tensor consisting a sum of the usual perfect-fluid energy–momentum tensor and some Belinfante–Rosenfeld tensors. It is shown that the equations of motion admit a solution for which the fluid four-velocity and four-momentum are not co-linear in general. The momentum and spin densities of the fluid are expressed in terms of the scale factor.     

Polarization mode conversion in an optical microdisk resonator vertically coupled to a waveguide bus

Due to the existence of non-zero, and asymmetrics cross-polarization coupling coefficients between a microdisk and a waveguide bus, high Q (∼10,000) overcoupled microdisks with minimal internal losses and sharp bending curvature (small radii) vertically coupled to a narrow-width ridge waveguide can be engineered as a proper candidate for a narrow-band polarization rotator. A semi-analytical calculation method is presented to realize microdisk-waveguide system as a polarization rotator.     

Demonstration of tunable complex refractive index of graphene covered one dimensional photonic crystals

Here, we report tunable complex optical properties of one dimensional photonic crystal covered by graphene layer, as a new optical material, in the visible spectral range. For this purpose, we fabricate two different structure as one dimensional photonic crystal, with photonic band gap which centered at 650 nm, by electron gun deposition method and the chemical vapor deposition has been used to synthesize graphene top layer. To demonstrate the optical properties of our two photonic crystals affected by graphene layer, we use the reflectance spectra of the samples as a function of incidence angle. Because the sufficient sensitivity of the refractive indices of the samples, we extract the real and imaginary part of these parameters in all of visible region as a tunable complex refractive index. Our results show that we have sufficient change due to excited plasmons in graphene layer by Bloch wave of photonic crystal which is very useful for sensor applications.     

Gravitational baryogenesis

We show that a gravitational interaction between the derivative of the Ricci scalar curvature and the baryon-number current dynamically breaks CPT in an expanding Universe and, combined with baryon-number-violating interactions, can drive the Universe towards an equilibrium baryon asymmetry that is observationally acceptable.     

Structural characterization and magnetoimpedance effect in amorphous and nanocrystalline AlGe-substituted FeSiBNbCu ribbons

Two series of rapidly solidified FINEMET (Fe_73.5Si_13.5B₉Nb₃Cu₁) alloys with and without partial substitution of Al (1.5 at%)/Ge (1 at%) were prepared by melt-spinning technique. The nanocrystallization process was carried out by the heat treatment of the as-spun ribbons at 560 °C for 1 h in a vacuum furnace. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimeter (DSC), Mössbauer spectroscopy, and magnetoimpedance (MI) measurements were conducted on the as-quenched and heat-treated alloys to investigate their structural and magnetic properties. The average crystallite sizes obtained for the heat-treated samples were in the range of 10–12 nm as confirmed by our XRD and TEM data. The ultrasoft magnetic behavior observed for the Al/Ge-substituted nanocrystalline alloys was confirmed both by our magnetic data and magnetoimpedance ratio (MIR%) results. A twofold increase in the magnitude of the MIR% (99%) was observed for the Al/Ge-substituted nanocrystalline alloy against that of the pure FINEMET alloy (∼48%) measured at 5.5 MHz. This is believed to be related to the decrease of the magnetocrystalline anisotropy as well as magnetostriction decline due to the Al substitution for Fe atoms in this nanostructured alloy.