Inverse spectral problems for energy-dependent Sturm-Liouville equations

We study the inverse spectral problem of reconstructing energy-dependent Sturm-Liouville equations from their Dirichlet spectra and sequences of the norming constants. For the class of problems under consideration, we give a complete description of the corresponding spectral data, suggest a reconstruction algorithm, and establish uniqueness of reconstruction. The approach is based on connection between spectral problems for energy-dependent Sturm-Liouville equations and for Dirac operators of special form.Comment: AMS-LaTeX, 28 page

Direct synthesis of 5-arylethynyl-1,2,4-triazines via direct CH-functionalization

An efficient synthetic approach towards 5-arylethynyl-1,2,4-triazines via direct C-H-functionalization of 5-H-1,2,4-triazines in reaction with lithium acetylenes is reported

Sturm-Liouville operators with measure-valued coefficients

We give a comprehensive treatment of Sturm-Liouville operators with measure-valued coefficients including, a full discussion of self-adjoint extensions and boundary conditions, resolvents, and Weyl-Titchmarsh theory. We avoid previous technical restrictions and, at the same time, extend all results to a larger class of operators. Our operators include classical Sturm-Liouville operators, Lax operators arising in the treatment of the Camassa-Holm equation, Jacobi operators, and Sturm-Liouville operators on time scales as special cases.Comment: 58 page

Synthesis of water-soluble gadolinium(iii) complexes based on 5-aryl-2,2'-bipyridine with a DTTA residue in position C6'

Two new Gd(III) complexes based on 5-aryl-2,2'-bipyridines with the DTTA residue at C6' position were obtained. Primary photophysical properties of new chelates have been studied. The resulting complexes are of interest by potential using, e.g., as contrast reagents for magnetic resonance imaging (MRI). © 2021 Author(s).Ministry of Education and Science of the Russian Federation, Minobrnauka, (075-15-2020-777)This work was supported by the Ministry of Science and Higher Education of the Russian Federation, Grant # 075-15-2020-77

New naphtho[1,8-ef]perimidines: synthesis, fluorescence studies and application for detection of nitroanalytes

Received: 15.12.2021. Revised: 20.12.2021. Accepted: 20.12.2021. Available online: 24.12.2021.A rational approach to the synthesis of substituted naphtho[1,8-ef]perimidines based on SN H methodology and cyclization reaction in the series of condensed azines with naphthalene substituents was presented. Photophysical properties of the obtained fluorophores were studied, in particular, green fluorescence in the 485–536 nm range with quantum yield up to 32.4% was detected. HOMO-LUMO energy values and distributions for the new compounds were calculated by the DFT method in comparison with nitroanalytes and perylene. Based on the data obtained, as well as on the results of fluorescence titration, the possibility of using the new diazaperylenes as potential chemosensors for the visual detection of nitrocontaining explosives was shown.This work was supported by Grants Council of the Presi-dent of the Russian Federation № NSh-2700.2020.3

Assessment of eutrophication abatement scenarios for the Baltic Sea by multi-model ensemble simulations

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Asymmetrically Functionalized 1,3-Di(2-pyridyl)benzenes: Synthesis and Photophysical Studies

A convenient synthetic approach to asymmetrically functionalized 1,3-di(2-pyridyl)benzenes starting from 3-(3-bromophenyl)-1,2,4-triazines using sequential aza-Diels–Alder reactions and Stille cross-coupling is reported. Photophysical properties of the obtained compounds are studied. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.This work was supported by Russian Science Foundation (Grant № 19-73-10144) and Grants Council of the President of the Russian Federation (no. NSh-2700.2020.3). No other sources of funding were involved

Synthesis of 2-Phenyl-2-(5-Phenyl-2,2'-Bipyridin-6-yl)-Acetonitrile by «1,2,4-Triazine» Method with Using Autoclave

This work was supported by the Russian Science Foundation (Ref. № 18-73-00301)

Sustainable Phosphorus Loadings from Effective and Cost-Effective Phosphorus Management Around the Baltic Sea

Nutrient over-enrichment of the Baltic Sea, accompanied by intensified algal blooms and decreasing water clarity, has aroused widespread concern in the surrounding countries during the last four decades. This work has used a well-tested dynamic mass-balance model to investigate which decrease in total phosphorus loading would be required to meet the environmental goal to restore the trophic state in the Baltic Sea to pre-1960s levels. Furthermore, the extent to which various abatement options may decrease the phosphorus loading in a cost-effective manner has been studied. Upgrading urban sewage treatment in the catchment could, alone or in combination with banning phosphates in detergents, be sufficient to meet the set environmental goal, at an estimated annual basin-wide cost of 0.21–0.43 billion euro. Such a plan would potentially decrease the total phosphorus loading to the Baltic Sea with 6,650–10,200 tonnes per year

The synthesis of aminophenyl-substituted 2,2'-bipyridine ligands by "1,2,4-triazine" methodology

A convenient synthetic approach to the 2,2'-bipyridines, including those with a condensed cyclopentene fragment, having an aminophenyl substituent at the C5 or C6 positions is reported. The products were obtained via their 1,2,4-triazine analogs with a nitro group, by the subsequent transformation of their 1,2,4-triazine ring into a pyridine one and the reduction of the nitro group to the amino group. © 2021 Author(s).Russian Science Foundation, RSF, (20-13-00142)Council on grants of the President of the Russian Federation, (NSh-2700.2020.3)This work was supported by the Russian Science Foundation (Grant # 20-13-00142) and by the Grants Council of the President of Russian Federation (Grant # NSh-2700.2020.3)