Rothe time-discretization method for a nonlinear parabolic p(u) -Laplacian problem with Fourier-type boundary condition and $$L^1$$ -data

Ricerche di Matematica - In this paper, we prove the existence and uniqueness results of entropy solutions to a class of nonlinear parabolic p(u)-Laplacian problem with Fourier-type boundary...     

Crystal Structure of Antitubercular Complex: <Emphasis Type="Italic">cis</Emphasis>-(chloro)-[<Emphasis Type="Italic">N,N</Emphasis>′-<Emphasis Type="Italic">bis</Emphasis>-(diethyl-2,2′-bipyridine-3,3′-dicarboxylate)]ruthenium(II) Monohydrate

Abstract  Diethyl-2,2′-bipyridine-3,3′-dicarboxylate (3 or L) reacts with RuCl₃ · 3H₂O to give cis-(Cl)-[Ru(L)₂Cl₂] · H₂O (4) and structure of the complex was determined by spectral (IR, ¹H-NMR), and mass spectroscopic data, elemental analyses and X-ray crystallography. The structure is solved in triclinic, space group p-1 with a = 10.658 (2), b = 12.446 (3), c = 14.186 (5) ?, α = 104.856 (3), β = 108.704 (3), γ = 94.973 (2)°, V = 1693.2 (8) ?³, Z = 2 with final R = 0.012. The geometry of the complex is shown to be a distorted octahedral with four nitrogens of two 2,2′-bipyridyl ligands in two different planes with Ru–N distance as 2.021 (2)−2.071 (3) ?. The cis-position is occupied by two chloride atoms with Ru–Cl distance as 2.4156 (12) and 2.4167 (13) ?. The trans-axial Cl2–Ru1–N and Cl1–Ru1–N4 angles are respectively, 172.42 (7) and 174.12 (7)°. A weak hydrogen bonding is observed between the two chlorides and hydrogens of neighbouring molecule [C–H···Cl distance as 2.72, 2.77 (4) ?]. A second type of weak hydrogen bonding is also observed between the oxygens of carboxylate groups and hydrogens of a neighbouring molecule [C–H···O distance as 2.53, 2.56 and 2.34 (4) ?]. Graphical Abstract  The structure of anti-tubercular precursor complexes, cis-(chloro)-[N,N′-bis-(diethyl-2,2′-bipyridine-3,3′-dicarboxylate)]ruthenium(II) monohydrate is solved by single crystal X-ray diffraction analysis which reveals geometry of the complex to be a distorted octahedral with four nitrogens of two 2,2′-bipyridyl ligands in two different planes. The cis-position is occupied by two chloride atoms.      

Encapsulation effect of π-conjugated quaterthiophene on the radial breathing and tangential modes of semiconducting and metallic single-walled carbon nanotubes

We developed a hybrid approach, combining the density functional theory, molecular mechanics, bond polarizability model and the spectral moment's method to compute the nonresonant Raman spectra of a single quaterthiophene (4T) molecule encapsulated into a single-walled carbon nanotube (metallic or semiconducting). We reported the optimal tube diameter allowing the 4T encapsulation. The influence of the encapsulation on the Raman modes of the 4T molecule and those of the nanotube (radial breathing modes and tangential modes) are analyzed. An eventual charge transfer between the 4T oligomer and the nanotube is discussed.     

Mesoporous pyrophyllite–titania nanocomposites: synthesis and activity in phenol photocatalytic degradation

Research on Chemical Intermediates - Pyrophyllite–TiO2 nanocomposite PTi750 was successfully synthesized using a sol–gel method at ambient temperature based on exfoliation of the...     

Synthesis of N,N′-bis and N,N,N′,N′-tetra-[(3,5-di-substituted-1-pyrazolyl)methyl]para-phenylenediamines: new candidate ligands for metal complex wires

A series of tridentate ligands N,N-bis-[(di-substituted-1-pyrazolyl)methyl]arylamines 2-3a,b and benzylamine 4a,b, tetradentate N,N′-bis-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 7a,b and hexadentate N,N,N′,N′-tetra-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 8a,b has been prepared in good yield by condensation of arylamines, benzylamine or para-phenylenediamine with N-hydroxymethyl disubstituted pyrazoles 1a,b. The synthesis and characterisation of these various polydentate ligands are described.     

Investigation of Temperature Effects on Cyclodextrin Compounds Through FT-IR Spectroscopy

Abstract

The infrared spectra of inclusion compounds of terephthalaldehyde and two aromatic esters with α- or β- cyclodextrin are studied. A wide range of temperatures provides significant modifications of the spectra which are explained by rotational isomerism of the guest molecule.     

Outstanding effect of the conformational restriction of isoquinolines: hints for the development of optimized antimicrobial agents

Conformational restriction constitutes a useful strategy of molecular modification for the design of new potential drug candidates. Herein we present the planning, antimicrobial evaluation, and establishment of structure–activity relationship (SAR) data for some isoxazole (3a–k, 8a–c, and 9a–c) and pyrazole (5a–h) derivatives. These derivatives were structurally designed by conformational restriction followed by bioisosteric exchange of previously described antimicrobial isoquinolines (1a–c). Some of these more conformationally restricted derivatives present improved properties as new antibacterial drug candidates.     

Poincaré maps modeling and local orbital stability analysis of discontinuous piecewise affine periodically driven systems

This paper presents a methodology to study the local stability of periodic orbits (orbital stability) in switched discontinuous piecewise affine (DPWA) periodically driven multiple-input multiple-output (MIMO) systems. The switched system of interest has a bilinear state space representation where the controller inputs are binary signals taking values in the set {0,1}. These systems are characterized by a set of affine differential equations together with switching rules to commute between them. These switching rules are described by switching functions that are periodic in time and linear in state. The methodology is based on obtaining a discrete time model (Poincaré map), its steady state operation points, and its Jacobian matrix. This provides a powerful tool for studying their stability and to predict some kind of instability phenomena that the system can undergo like subharmonic oscillations. The proposed approach is applied to a power electronic circuit which toggles among six different system equations with five switching boundaries within a switching cycle. This work was supported by the Spanish Ministerio de Educación y Ciencia under Grant TEC-2004-05608-C02-02.