HgO/I2 as an Efficient Reagent for the Oxidative Aromatization of Hantzsch 1-NH, 4-Dihydropyridines under Mild and Heterogeneous Conditions

A variety of Hantzsch 1-NH, 4-dihydropyridines were efficiently aromatized to the corresponding pyridine derivatives by treatment with HgO/I2 reagent in dichloromethane under mild and  heterogeneous conditions in good to excellent yields at room temperature. The products were separated by simple filtration and evaporation of the solvent.KEYWORDS: HgO/I2, Hantzsch 1,4-dihydropyridine, aromatization, heterogeneous

Silica-Supported Yttrium Nitrate Hexahydrate as a Heterogeneous Catalyst for the Synthesis of 2-Amino-4H-Chromenes in Water

Silica-supported yttrium nitrate hexahydrate (Y(NO3)3.6H2O/SiO2) has been found to be an efficient and reusable catalyst for the synthesis of 2-amino-4H-chromenes via a one-pot aqueous three-component reaction between arylaldehydes, malononitrile and â-naphthol in high yields. This method has many appealing attributes such as excellent yields, short reactions time, reusability of the catalyst and simple work-up procedure.KEYWORDS: Silica-supported yttrium nitrate hexahydrate, 2-amino-4H-chromene, malononitrile, arylaldehyde, β-naphthol

A Facile and Practical p-Toluenesulfonic Acid Catalyzed Route to Dicoumarols Containing an Aroyl group

New and known dicoumarols may be efficiently synthesized employing p-toluenesulfonic acid (p-TSA) as a solid acid catalyst from the reaction of 4-hydroxycoumarin with aryl glyoxal in water. This method offers direct access to structurally diverse coumarin derivatives in moderate to good yields (up to 65%). A total of five new compounds were synthesized.KEYWORDS Dicoumarol, p-toluenesulfonic acid, aryl glyoxal, 4-hydroxycoumarin.PDF and Supp files attache

Interacting entropy-corrected new agegraphic dark energy in Brans-Dicke cosmology

Motivated by a recent work of one of us [1], we extend it by using quantum (or entropy) corrected new agegraphic dark energy in the Brans-Dicke cosmology. The correction terms are motivated from the loop quantum gravity which is one of the competitive theories of quantum gravity. Taking the non-flat background spacetime along with the conformal age of the universe as the length scale, we derive the dynamical equation of state of dark energy and the deceleration parameter. An important consequence of this study is the phantom divide scenario with entropy-corrected new agegraphic dark energy. Moreover, we assume a system of dark matter, radiation and dark energy, while the later interacts only with dark matter. We obtain some essential expressions related with dark energy dynamics. The cosmic coincidence problem is also resolved in our model.Comment: 16 pages, no figure, accepted for publication in Gen. Relativ. Gra

Growth factor in f(T) gravity

We derive the evolution equation of growth factor for the matter over-dense perturbation in $f(T)$ gravity. For instance, we investigate its behavior in power law model at small redshift and compare it to the prediction of $\Lambda$CDM and dark energy with the same equation of state in the framework of Einstein general relativity. We find that the perturbation in $f(T)$ gravity grows slower than that in Einstein general relativity if \p f/\p T>0 due to the effectively weakened gravity.Comment: 15 pages,1 figure; v2,typos corrected; v3, discussions added, accepted by JCA

Assessing the role of Ca2+ in skeletal muscle fatigue using a multi-scale continuum model

The Calcium ion Ca2+ plays a critical role as an initiator and preserving agent of the cross-bridge cycle in the force generation of skeletal muscle. A new multi-scale chemo-mechanical model is presented in order to analyze the role of Ca2+ in muscle fatigue and to predict fatigue behavior. To this end, a cross-bridge kinematic model was incorporated in a continuum based mechanical model, considering a thermodynamic compatible framework. The contractile velocity and the generated active force were directly related to the force-bearing states that were considered for the cross-bridge cycle. In order to determine the values of the model parameters, the output results of an isometric simulation were initially fitted with experimental data obtained for rabbit Extensor Digitorum Longus muscle. Furthermore, a simulated force-velocity curve under concentric contractions was compared with reported experimental results. Finally, by varying the Ca2+ concentration level and its kinetics in the tissue, the model was able to predict the evolution of the active force of an experimental fatigue protocol. The good agreement observed between the simulated results and the experimental outcomes proves the ability of the model to reproduce the fatigue behavior and its applicability for more detailed multidisciplinary investigations related to chemical conditions in muscle performance