An unusual result of the reaction of α-acetylene aldehydes,pyridines, and malonic acid. Synthesis and structure of novel pyridine betaines

Chemistry of Heterocyclic Compounds - 5-Aryl-2-carboxy-5-(pyridin-1-ium-1-yl)penta-2,4-dienoates, previously unknown pyridine betaines, were formed in 32–70% yields as a result of the...     

Scalar dark energy models mimicking ΛCDM with arbitrary future evolution

Dark energy models with various scenarios of evolution are considered from the viewpoint of the formalism for the equation of state. It is shown that these models are compatible with current astronomical data. Some of the models presented here evolve arbitrarily close to ΛCDM up to the present, but diverge in the future into a number of different possible asymptotic states, including asymptotic de Sitter (pseudo-rip) evolution, little rips with disintegration of bound structures, and various forms of finite-time future singularities. Therefore it is impossible from observational data to determine whether the universe will end in a future singularity or not. We demonstrate that the models under consideration are stable for a long period of time (billions of years) before entering a Little Rip/Pseudo-Rip induced dissolution of bound structures or before entering a soft finite-time future singularity. Finally, the physical consequences of Little Rip, Types II, III and Big Crush singularities are briefly compared.     

On a simple oscillator problem describing ice-induced vibrations of an offshore structure

Nonlinear Dynamics - In this paper, a new simple oscillator model is considered describing ice-induced vibrations of upstanding, water-surrounded, and bottom-founded offshore structures. Existing...     

The efficient synthesis of substituted 2-methylbenzofurans

Chemistry of Heterocyclic Compounds - The efficient synthesis of substituted 2-methylbenzofurans by aromatization of accessible allyl-substituted cyclohex-2-enones in the presence of iodine...     

Facile synthesis of macrocyclic tetrazoles by regioselective cycloalkylation of bistetrazoles with 2,5-dimethylhexane-2,5-diol in perchloric acid

Alkylation of 1,5-bis(tetrazol-5-yl)-3-oxapentane with 2,5-dimethylhexane-2,5-diol in 65% aqueous perchloric acid was found to proceed selectively on the N2 atoms of both tetrazole rings generating a 15-membered macrocycle with tetrazol-2,5-diyl moieties incorporated (yield ca. 80%). Under analogous alkylation conditions 1,5-bis(1-methyltetrazol-5-yl)-3-oxapentane undergoes quaternization resulting in a macrocyclic tetrazolium perchlorate containing two 1-methyltetrazolium-3,5-diyl units linked by 3-oxapentane-1,5-diyl and 2,5-dimethylhexane-2,5-diyl bridges. Crystal structures of the macrocyclic compounds obtained, determined by single crystal X-ray analysis, are described.     

Uniform convergence of Green’s functions

Given a sequence of regular planar domains converging in the sense of kernel, we prove that the corresponding Green’s functions converge uniformly on the complex sphere, provided the limit domain is also regular, and the connectivity is uniformly bounded.     

Aromatic-Like Carbon Nanostructures Created on the Vicinal SiC Surfaces

Physics of the Solid State - Electronic structure of the ultrathin Cs, Ba/SiC(111)-4°, 8° interfaces have been studied in situ in an ultrahigh vacuum using synchrotron-based photoelectron...     

Damage evolution in an expanding/contracting hollow sphere at large strains

A generalization of one of the classical problems of plasticity theory, expansion/contraction of a hollow sphere, is proposed assuming that the conventional constitutive equations for rigid plastic, hardening material are supplemented with an arbitrary ductile damage evolution law. No restriction is imposed on the hardening law in the analytic part of the solution. The initial/boundary value problem is reduced to two equations in characteristic coordinates. A numerical scheme to solve these equations is proposed. An illustrative example is given.