An approach to solutions of coupled semilinear partial differential equations with applications

In this work, an approach for finding the solution of coupled semi‐linear diffusion equations for initial value problems is presented. The formal exact solution is found and the Picard iteration is constructed. It is shown that the constructed sequence of solutions converges uniformly for some classes of initial value problems. The problem of dispersion of an oxygen demanding pollutant released into a uniform flow is studied. Copyright © 2000 John Wiley & Sons, Ltd.     

Three‐component 1,3‐dipolar cycloaddition reactions in synthesis of spiro[pyrrolidine‐2,3′‐oxindoline] derivatives

Regio‐ and stereospecific syntheses of several spiro[pyrrolidine2,3′‐oxindole] derivatives by cycloaddition trapping of azomethine ylides generated in situ, via decarboxylative condensation of isatin with α‐amino acids or by reaction of secondary amines with isatin, are reported. 2,6‐Dibenzylidenecyclohexanone, 2‐arylidene‐1‐tetralone, and arylidenemalononitrile derivatives have been efficiently used as trapping dipolarophiles. The regio‐ and stereochemistry of the additions are controlled by both frontier orbital and steric interactions. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:324–329, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10038     

Pyrolysis of aminonitriles,cyanohydrazones, and cyanoacetamides. Part I. Elimination reaction of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles and substituted benzaldehyde cyanoacetylhydrazones

Pyrolysis of the Schiff bases of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles (1–5) has been studied. These compounds eliminate via a six-membered transition state to produce substituted benzonitriles and 2-hydroxy-4,6-dimethylpyridine-3-carbonitrile. These eliminations are unimolecular first-order reactions. The kinetic data gave a good correlation with σ⁰ values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open-chain substituted benzaldehyde cyanoacetylhydrazones (6–9) analogues. © 1996 John Wiley & Sons, Inc.     

A damage identification technique for beam-like and truss structures based on FRF and Bat Algorithm

In this paper, a Structural Health Monitoring (SHM) technique for damage identification in beam-like and truss structures using Frequency Response Function (FRF) data coupled with optimization techniques is presented. Genetic Algorithm (GA) and Bat Algorithm (BA) are used to estimate the location and severity of damage. The damage in the structures is simulated by reduction in rigidity of specific members. Both optimization techniques are coupled with modelled structures using Finite Element Method (FEM). The approach is based on minimizing an objective function by comparing measured and calculated FRFs. The results show that better accuracy is obtained using BA than using GA in terms of precision and computational time. Furthermore, it is found that the proposed approach provides faster solution than other approaches in the literature.     

Synthesis, structure characterization and magnetic properties of nanosize LiCo1 − y Ni y O2 prepared by sol–gel citric acid route

Single phase LiCo_1 − y Ni _y O₂ (y = 0.4 and 0.5) with fine particles and high homogeneity was synthesized by “chimie douce” assisted by citric acid as the polymeric agent and investigated as positive electrodes in rechargeable lithium batteries. The long-range and short-range structural properties are investigated with experiments including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and superconducting quantum interference device magnetometry. The physicochemical properties of the powders (crystallinity, lattice constants, grain size) have been investigated in this composition. The powders adopted the α-NaFeO₂ structure as it appeared from XRD and FTIR results. Magnetic measurements shows signal at low temperature attributed to the magnetic domains in the nanostructure sample from which we estimated that the cation mixing are 3.35 and 4.74% for y = 0.4 and 0.5 in LiCo_1 − y Ni _y O₂, respectively. LiCo_0.5Ni_0.5O₂ cathode yields capacity (135 mAh g⁻¹) compared to LiCo_0.6Ni_0.4O₂ cathode (147 mAh g⁻¹) when discharged to a cutoff voltage of 2.9 V vs. Li/Li⁺. Lower capacity loss and higher discharge efficiency percentage are observed for the cell of LiCo_0.6Ni_0.4O₂ cathode.     

Inclusion complexes of a nucleotide analogue with hydroxypropyl-beta-cyclodextrin

Bis(tbutyl-S-acyl-2-thioethyl)-AraCMP (UA911) is a mononucleotide prodrug developed to overcome some of the cellular resistance to cytotoxic deoxynucleosides analogues. Its use for in vivo studies is limited due to its poor solubility in water. Thus, 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) was proposed to solubilize UA911 in water, in order to obtain concentrations needed for in vivo experiments. A molar ratio of HP-β-CD: UA911 of 3:1 was sufficient to obtain complete solubilization of the prodrug. The corresponding inclusion complex was characterized by differential scanning calorimetry and ¹H NMR spectroscopy study provided a definitive proof of the formation of the inclusion complex. The complex retained its cytotoxic activity as shown by in vitro cell survival assays on murine leukemia cells, and was evaluated in vivo. HP-β-CD is therefore suitable for the preparation of adequate solutions for the study of the antitumoral activity of nucleotide prodrugs such as UA911.     

Complexation of N-methyl-4-(p-methyl benzoyl)-pyridinium methyl cation and its neutral analogue by cucurbit[7]uril and β-cyclodextrin: a computational study

In this work, molecular dynamics (MD) simulations have been conducted to study the inclusion complexes between cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD) with N-methyl-4-(p-methyl benzoyl)-pyridinium methyl cation, and N-methyl-4-(p-methyl benzoyl)-pyridine in aqueous solutions to gain detailed information about the dynamics and mechanism of the inclusion complexes. The obtained MD trajectories were used to estimate the binding free energy of the studied complexes using the molecular mechanics/Poisson Bolzmann surface area (MM–PBSA) method. Results indicate preference of CB7 to bind to the cationic guest more than the neutral guest, whereas β-CD exhibits more or less the same affinity to complex with either species. Furthermore it was interesting to note that β-CD forms more stable complexes with both guests than CB7. Average structure of each complex and the distances between the center of masses of the guest and the host were also discussed.     

Studies with 3‐functionally substituted 2‐arylhydrazononitriles: A new route to 3‐substituted‐2‐arylhydrazononitriles, 4‐amino‐pyrazole‐5‐carbonitriles,azadienes and cinnolines

3‐Amino‐3‐phenyl‐2‐phenylazoacrylonitrile 6 is obtained in good yield via reaction of 5 with phenyl magnesium bromide. The compound 6 is readily converted into 4a . The so formed alkanenitrile reacted with phenylmagnesium bromide to yield 8 . Compound 8 could be also obtained from reaction of 9 with phenylmagnesium bromide. The arylhydrazononitriles 8 and 4a reacted with chloroacetonitrile to yield the 4‐aminopyrazoles 12a,b . Compound 12a reacted with acetic anhydride to yield the 15a and with benzoyl chloride to yield the pyrazole 16 which was converted into 15b . Refluxing 10 in acetic acid gave a mixture of the azadiene 21 and the cinnoline 22 is obtained. The azadiene 21 is converted into 22 either thermally or photochemically.     

On thermodynamic self-consistency of generic axiomatic-nonextensive statistics

Generic axiomatic-nonextensive statistics introduces two asymptotic properties,to each of which a scaling function is assigned.The first and second scaling properties are characterized by the exponents c and d,respectively.In the thermodynamic limit,a grand-canonical ensemble can be formulated.The thermodynamic properties of a relativistic ideal gas of hadron resonances are studied,analytically.It is found that this generic statistics satisfies the requirements of the equilibrium thermodynamics.Essential aspects of the thermodynamic self-consistency are clarified.Analytical expressions are proposed for the statistical fits of various transverse momentum distributions measured in most-central collisions at different collision energies and colliding systems.Estimations for the freezeout temperature(T_(ch)) and the baryon chemical potential(μ_b) and the exponents c and d are determined.The earlier are found compatible with the parameters deduced from Boltzmann-Gibbs(BG) statistics(extensive),while the latter refer to generic nonextensivities.The resulting equivalence class(c,d) is associated with stretched exponentials,where Lambert function reaches its asymptotic stability.In some measurements,the resulting nonextensive entropy is linearly composed on extensive entropies.Apart from power-scaling,the particle ratios and yields are excellent quantities to highlighting whether the particle production takes place(non)extensively.Various particle ratios and yields measured by the STAR experiment in central collisions at 200,62.4 and 7.7 GeV are fitted with this novel approach.We found that both c and d 1,i.e.referring to neither BG-nor Tsallis-type statistics,but to(c,d)-entropy,where Lambert functions exponentially rise.The freezeout temperature and baryon chemical potential are found comparable with the ones deduced from BG statistics(extensive).We conclude that the particle production at STAR energies is likely a nonextensive process but not necessarily BG or Tsallis type.