Integral manifolds and the reduction principle in stability theory. III

It is shown how, with the help of approximate integral manifolds, to solve the reduction problem in stability theory in the nonsingular critical case. A generalization of the first fundamental Lyapunov-Malkin theorem in critical cases is obtained.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 10, pp. 1324–1329, October, 1991.     

Protonation of acyl anion equivalents generated from acylphosphonates: nonhydride access to the aldehyde oxidation state from the carboxylic acid oxidation state

Acylphosphonates, which are easily available from carboxylic acids, are potent acyl anion precursors and undergo cyanide ion promoted phosphonate-phosphate rearrangement to provide the corresponding acyl anion equivalents as reactive intermediates. The protonation of these acyl anion equivalents furnished cyanohydrin O-phosphates in good yields. For the high yield formation of cyanohydrin O-phosphates from arylphosphonates THF should be used and from alkylphosphonates DME was used.     

Effect of chemical demineralization on thermal behavior of bituminous coals

Growing environmental concerns and the need for alternatives for oil and natural gas resulted in intensive researches on ultra clean coal (UCC). Therefore, the researches related to practice and application of various methods to produce UCC become more important. Thermal characterization of chemically demineralized coals by thermogravimetric analysis method is presented in this study. The aim of the study is to provide thermal data for HF–HNO₃ leaching system used for the production of UCC. Coal samples were first physically enriched by density separation. Then the enriched portion was chemically demineralized by using HF and HNO3, respectively. Ash content of coal samples were reduced to a range of 0.12–0.41% by chemical demineralization process. The petrographic, ultimate and proximate analyses were carried out to determine main features of samples. Physically and chemically enriched coal samples were then analyzed in a TG by two different techniques separately. The first technique covered thermal characterization of samples under non-isothermal conditions. Characteristic temperatures for each sample were obtained from the TG and DTG data. The second technique involved the determination of reactivity of in situ produced chars of each sample.     

A Comment on Change of Nusselt Number Sign in a Channel Flow Filled by a Fluid-Saturated Porous Medium with Constant Heat Flux Boundary Conditions

The aim of this Letter is to show that, the Nusselt number sign might be changed without changing of heat transfer direction at the wall of channels, even for flows without viscous dissipation.     

Unexpected formation of β, meso-directly linked diporphyrins under Adler–Longo reaction conditions

Unexpected formation of β, meso-directly linked diporphyrin products has been described in the reactions of β-formyl porphyrins with pyrrole under Adler–Longo reaction conditions. Preliminary mechanistic studies indicates that β-dipyrromethane substituted porphyrin structure is the crucial intermediate for the formation of diporphyrin product.     

Thermally induced fixed diradical generation on solid supports for surface‐initiated polymerization

A method is presented for generation of all surface‐bound radicals on solid polymer surfaces. Thus, secondary amide group of newly synthesized crosslinking comonomer, methacryloyloxyethyl methacrylamide was determined as versatile precursor for generation fixed diradicals on solid microspheres, obtained by copolymerization with methyl methacrylate (MMA) in aqueous suspension. Nitrosoation of the secondary amide groups on the microbeads and followed thermolysis above 90 °C was demonstrated to give surface‐bound radicals, capable of initiating polymerization of vinyl monomers, such as; styrene, MMA, N‐vinyl formamide, and N‐vinyl, 2‐pyrrolidone, as evidenced by H NMR, Fourier transform infrared, thermogravimetric analysis, and differential scanning calorimeter techniques. Appreciable grafting yields (55.1%–286.1%) and low free‐homopolymer formation (7.2%–19.7%) were noted within 6 h of the grafting at 100 °C in each case. This strategy involving the use of amide functional crosslinker seemed to be generally applicable to generate surface‐bound radicals for surface‐initiated polymerization from various solid substrates. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A new reagent for the synthesis of [26]hexaphyrin: N-sulfonyl aldimine

The selective synthesis of [26]hexaphyrin(1.1.1.1.1.1) has been achieved by the reaction of meso-substituted tripyrrane and N-sulfonyl aldimine. The protocol is simple and requires only a catalytic amount of copper(II) triflate under mild reaction conditions.     

Sparticle mass hierarchies,simplified models from SUGRA unification,and benchmarks for LHC Run-II SUSY searches

Journal of High Energy Physics - We consider the AdS 2 /CFT 1 holographic correspondence near the horizon of rotating five-dimensional black holes preserving four supersymmetries in $$...     

Synthesis and characterization of sulfone containing main chain oligobenzoxazine precursors

The preparation of soluble and processable polybenzoxazine precursors capable of forming high performance networks is an important field of research with a broad spectrum of application. This study demonstrates an approach that utilizes aromatic sulfonediamine, bisphenol‐A, and formaldehyde in Mannich‐type polycondesation to prepare polybenzoxazine precursor. The structure of the oligomeric precursor (M_n = 2600) was confirmed by FTIR and ¹H NMR spectral analysis. The precursor contained both sulfone and benzoxazine ring structures in the backbone. It was shown that small amount of ring‐opened phenolic groups were also present. Thermally activated self‐curing behavior of precursor in the absence of catalyst was studied by differential scanning calorimetry. Thermal properties of the cured polymers were also investigated by thermo gravimetric analysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011