Two compressible immiscible fluids in porous media

We consider a model of flow of two compressible and immiscible phases in a three-dimensional porous media. The equations are obtained by the conservation of the mass of each phase. This model is treated in its general form with the whole nonlinear terms. The only assumption concerns the dependence of densities on a global pressure. We obtain the existence of weak solutions under different kinds of degeneracies of the capillary terms.     

Analogous study in low magnetic field between Cu–Ge and Cu–Si ferrites

Two series of mixed copper ferrites, Cu_1+x Ge_x Fe_2−2x O₄ and Cu_1+x Si_x Fe_2−2x O₄, have been analogously investigated for x=0.0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3. The two systems were prepared using the standard ceramic techniques. X-ray diffraction analysis indicates that both systems formed in a single phase cubic spinel structure. The lattice parameter has a constant value (0.838 nm±0.001) for the two series. The grain diameter was estimated from the scanning electron microscope micrographs for the two series. Some magnetic properties were measured at room temperature. The magnetization M was measured in the range of magnetizing field up to 5500 Am⁻¹. The relative permeability (μ_r) was calculated from the B–H relation. The B–H loops were measured at constant magnetizing current (I=2.5 A which is equivalent to 900 Am⁻¹). Also, the hystersis area and the magnetic parameters B_r, B_s, m_R (B_r/B_s) and apparent energy loss (E) were estimated from the B–H loops; μ_r, B_r, B_s and E are composition dependent.     

A study of the conduction mechanism of single crystal Li0.5Fe2.5O4 through the transition points

The differential thermal analysis, electrical resistivity and thermopower are studied as a function of temperature in the range 300–1100 K. The measurements show two transition points at 905 and 1030 K. The first point is linked with the magnetic transition at the Néel temperature (T_N), and the second with the order-disorder phase. The conduction mechanism through the Néel point is discussed using the spin polaron model.     

Influence of hyperbranched polyesters on the surface tension of polyols

The influence of hyperbranched polyesters with different functional end groups on the surface tension of mixtures with an oligo(ester diol) was investigated. The temperature dependence of the surface tension of the pure components and of the mixtures was measured by a modified Wilhelmy balance technique. The results indicate that the surface tension of the pure hyperbranched polyesters strongly depends on the functionality of the end groups. The functionalization of the hydroxyl end groups by short alkyl chains (methyl, tert-butyl) reduced the surface tension depending on the degree of substitution. The surface tension of the mixtures with the hydroxyl-terminated hyperbranched polyester was slightly increased at higher concentrations of the hyperbranched polymer compared to the surface tension of the pure ester diol. On the other hand, the surface tension of mixtures could be considerably decreased using 1% of hyperbranched polyester polyols partially substituted with short alkyl chains. In that case, the modified hyperbranched polyesters act as surface active agents. On the molecular level, the enrichment of the modified hyperbranched polyester in the surface region was proven by X-ray photoelectron spectroscopy measurements.     

Synthesis of some 1-hydroxy derivatives of 4- and 6-azaindole analogues

1-Hydroxy-4-azaindole and 1-hydroxy-4-(and 6)-azaindol-2(3H)-one derivatives are novel compounds and a facile synthesis by the reductive cyclisation of substituted 3-nitropyridines is described. Problems associated with the catalytic hydrogenation of the parent nitro compounds are also discussed.     

High yielding selective access to spirocyclopropanated 5-oxopiperazine-2-carboxylates and 1,4-diazepane-2,5-diones from methyl 2-chloro-2-cyclopropylideneacetate

The 2-spirocyclopropanated methyl 5-oxopiperazine-2-carboxylate and the 3-spirocyclopropanated 6-chloro-1,4-diazepane-2,5-dione could both be prepared at choice in 93 and 88% yield, respectively, from methyl 2-chloro-2-cyclopropylideneacetate () in a sequence of Michael addition of 3-benzyloxypropylamine, peptide coupling with N-Boc-glycine, Boc-group removal and cyclization. Transformation of the benzyloxypropyl side chain, peptide coupling with N-Boc-(S)-asparagine, deprotection and repeated cyclization led to the octahydro[2H]pyrazino[1,2-a]pyrazinetrione scaffold containing a rigidified mimic of a tripeptide with a DGR motif. The overall yield of after deprotection of (a total of 13 steps in 8 distinct operations) was 30%.     

Neuroprotective Potential of Synthetic Mono-Carbonyl Curcumin Analogs Assessed by Molecular Docking Studies

Cognitive decline in dementia is associated with deficiency of the cholinergic system. In this study, five mono-carbonyl curcumin analogs were synthesized, and on the basis of their promising in vitro anticholinesterase activities, they were further investigated for in vivo neuroprotective and memory enhancing effects in scopolamine-induced amnesia using elevated plus maze (EPM) and novel object recognition (NOR) behavioral mice models. The effects of the synthesized compounds on the cholinergic system involvement in the brain hippocampus and their binding mode in the active site of cholinesterases were also determined. Compound h2 (p < 0.001) and h3 (p < 0.001) significantly inhibited the cholinesterases and reversed the effects of scopolamine by significantly reducing TLT (p < 0.001) in EPM, while (p < 0.001) increased the time exploring the novel object. The % discrimination index (DI) was significantly increased (p < 0.001) in the novel object recognition test. The mechanism of cholinesterase inhibition was further validated through molecular docking study using MOE software. The results obtained from the in vitro, in vivo and ex vivo studies showed that the synthesized curcumin analogs exhibited significantly higher memory-enhancing potential, and h3 could be an effective neuroprotective agent. However, more study is suggested to explore its exact mechanism of action.     

Designing of Smooth Composite Panels Providing Stability and Strength at Postbuckling Behavior

Mechanics of Composite Materials - Buckling of skin is admissible for upper load-bearing panels of a wing box and mechanization units of a light aircraft in case of loads close to operating level....     

The Influence of Various Divalent Metal Ions (Mn2+, Co2+, and Cu2+) Substitution on the Structural and Magnetic Properties of Nickel–Zinc Spinel Ferrite

Physics of the Solid State - Ni0.7&nbsp;–&nbsp;xZn0.3MxFe2O4 (M = Mn2+, Co2+, and Cu2+; x = 0, 0.1, 0.3, 0.5, and 0.7) spinel-type ferrite were fabricated through citrate technique....