A convenient synthesis of new pyrido[3,2-e][1,4]diazepine-2,5-diones and pyrido[2,3-e][1,4]diazepine-2,5-diones

A convenient synthesis of a series of pyrido[3,2-e][1,4]-diazepine-2,5-diones 8 and pyrido[2,3-e][1,4]diazepine-2,5-diones 9, is reported using the condensation of α-amino acid methyl ester derivatives with 1H-pyrido[3,2-d][1,3]oxazine-2,4-dione and 1H-pyrido[2,3-d][1,3]oxazine-2,4-dione. Compounds 8 and 9 were also synthesized by peptide coupling of α-amino acid methyl ester derivatives with β-amino acids (2 or 3) followed by the cyclisation in tetrahydrofuran with sodium hydride (NaH).     

A novel and convenient method for the synthesis of new derivatives of pyrido[3,2-e]pyrrolo[1,2-a][1,4]diazepine-6,11-dione

A novel methodology has been developed for the efficient synthesis of 1,4-pyridopyrrolodiazepine derivatives. The key reaction is the bromination under mild conditions by NBS of compounds resulting via peptide coupling of l-proline methyl ester with 3-aminopyridine-2-carboxylic acid 1, then intramolecular cyclization in the construction of 2-bromo-6a,7,8,9-tetrahydro-5H-pyrido[3,2-e]pyrrolo[1,2-a][1,4]diazepine-6,11-dione 4. This latter is then engaged in cross-coupling reactions to generate 1,4-pyridopyrrolodiazepines derivatives 5a-m, 6a-i, 7, and 8a-c. This strategy provides an efficient method to access a library of compounds based on privileged substructures that are of great interest in drug discovery.     

On the convergence of inexact Newton methods for discrete-time algebraic Riccati equations

In this paper, we present a convergence analysis of the inexact Newton method for solving Discrete-time algebraic Riccati equations (DAREs) for large and sparse systems. The inexact Newton method requires, at each iteration, the solution of a symmetric Stein matrix equation. These linear matrix equations are solved approximatively by the alternating directions implicit (ADI) or Smith?s methods. We give some new matrix identities that will allow us to derive new theoretical convergence results for the obtained inexact Newton sequences. We show that under some necessary conditions the approximate solutions satisfy some desired properties such as the d-stability. The theoretical results developed in this paper are an extension to the discrete case of the analysis performed by Feitzinger et al. (2009) [8] for the continuous-time algebraic Riccati equations. In the last section, we give some numerical experiments.     

Singular soliton solution and bifurcation analysis of Klein-Gordon equation with power law nonlinearity

In this paper, the Klein-Gordon equation (KGE) with power law nonlinearity will be considered. The bifurcation analysis as well as the ansatz method of integration will be applied to extract soliton and other wave solutions. In particular, the second approach to integration will lead to a singular soliton solution. However, the bifurcation analysis will reveal several other solutions that are of prime importance in relativistic quantum mechanics where this equation appears.     

Impact of the meteorological parameters on the behaviour of 7Be at ground level in Tetouan city,Morocco from June 2015 to February 2017

For the first time, atmospheric aerosols were collected in Tetouan city (Morocco), from June 2015 to February 2017, through which ⁷Be activity was measured. We studied data variation by time series analyses and the impact of local meteorological factors on it. ⁷Be concentrations, in mBq/m³, ranged from 1.65 to 7.79 with mean value of 4.69. ⁷Be behaviour is mainly influenced by air temperature, precipitations, relative humidity and atmospheric pressure. A prediction model was suggested and validated. This study helps understanding climatic variables impact on the environmental processes as aerosols transport and deposit, and to predict ⁷Be behaviour in Mediterranean regions like Tetouan.

     

A microstructure-based model for time-dependent mechanics of multi-layered soft tissues and its application to intervertebral disc annulus

Meccanica - In recent experimental studies an unusual time-dependent transversal behavior of the annulus fibrosus of the intervertebral disc mainly caused by the coupling between mechanics and...     

Perturbation of super-Gaussian optical solitons in dispersion-managed fibers

This paper studies the perturbation of dispersion-managed optical solitons in polarization-preserving optical fibers due to the perturbation terms. The types of pulses that are considered in this paper are super-Gaussian. The adiabatic parameter dynamics of such solitons are obtained in the presence of these local as well as non-local perturbation terms.     

Optical soliton perturbation in a non-Kerr law media

This paper studies the optical soliton perturbation by the aid of soliton perturbation theory. The various perturbation terms, that arise in the study of optical solitons, are exhaustively studied in this paper. The adiabatic parameter dynamics of optical solitons are obtained in presence of these perturbation terms. The types of nonlinearities that are considered are Kerr law, power law, parabolic law as well as the dual-power law.     

Experimental and modeling study of the high-temperature combustion chemistry of tetrahydrofurfuryl alcohol

Lignocellulosic tetrahydrofuranic (THF) biofuels have been identified as promising fuel candidates for spark-ignition (SI) engines. To support the potential use as transportation biofuels, fundamental studies of their combustion and emission behavior are highly important. In the present study, the high-temperature (HT) combustion chemistry of tetrahydrofurfuryl alcohol (THFA), a THF based biofuel, was investigated using a comprehensive experimental and numerical approach.Representative chemical species profiles in a stoichiometric premixed methane flame doped with ～20% (molar) THFA at 5.3 kPa were measured using online gas chromatography. The flame temperature was obtained by NO laser-induced fluorescence (LIF) thermometry. More than 40 chemical products were identified and quantified. Many of them such as ethylene, formaldehyde, acrolein, allyl alcohol, 2,3-dihydrofuran, 3,4-dihydropyran, 4-pentenal, and tetrahydrofuran-2-carbaldehyde are fuel-specific decomposition products formed in rather high concentrations. In the numerical part, as a complement to kinetic modeling, high-level theoretical calculations were performed to identify plausible reaction pathways that lead to the observed products. Furthermore, the rate coefficients of important reactions and the thermochemical properties of the related species were calculated. A detailed kinetic model for high-temperature combustion of THFA was developed, which reasonably predicts the experimental data. Subsequent rate analysis showed that THFA is mainly consumed by H-abstraction reactions yielding several fuel radicals that in turn undergo either β-scission reactions or intramolecular radical addition that effectively leads to ring enlargement. The importance of specific reaction channels generally correlates with bond dissociation energies. Along THFA reaction routes, the derived species with cis configuration were found to be thermodynamically more stable than their corresponding trans configuration, which differs from usual observations for hydrocarbons.