The spectral maximum of synchrotron radiation

A three-level system is considered as a simplest example where a possibility of solving the spectral problem is observed. We thoroughly analyze the relation between the amount of radiation emitted by the particle during the transitions to the first excited state and to the ground state. Generalizing basic expressions we can follow the evolution of spectral maximum. It turns out there is a condition for radiation maximum to stay at highest harmonic.     

Spatiotemporal model for the progression of transgressive dunes

Transgressive dune fields, which are active sand areas surrounded by vegetation, exist on many coasts. In some regions like in Fraser Island in Australia, small dunes shrink while large ones grow, although both experience the same climatic conditions. We propose a general mathematical model for the spatiotemporal dynamics of vegetation cover on sand dunes and focus on the dynamics of transgressive dunes. Among other possibilities, the model predicts growth parallel to the wind with shrinkage perpendicular to the wind, where, depending on geometry and size, a transgressive dune can initially grow although eventually shrink. The larger is the initial area the slower its stabilization process. The model’s predictions are supported by field observations from Fraser Island in Australia.     

An Alternative Procedure for the Aluminum-Mediated Conversion of Esters to Amides

A convenient method has been developed for directly converting esters to amides using reagents derived from the reaction of trimethylaluminum with ammonium chloride, methylamine hydrochloride or dimethylamine hydrochloride.     

Synthesis of 5,10,15,20-tetra[6' -nitro-1,3,3-trimethylspiro- (indolino-2,2' -2H-chromen-5-yl)]porphyrin and its metal complexes

A new 5,10,15,20-tetrasubstituted porphyrin containing four 6’-nitro-1,3,3-trimethylspiro(indolino-2,2’-2H-chromene) substituents and its complexes with Zn²⁺ and Cu²⁺ ions were prepared and characterized by physicochemical methods of analysis.     

Synthesis of high-purity lower silicon alcoholates for new technology

Purification of a number of silicon derivatives (chloride, lower alcoholates) formed in processing of high-purity silicon for electronic and electrical industries was considered. It was found that high-purity substances suitable for use in electronics and optics can be produced from industrial wastes.     

Structure of the electromagnetic field allowing exact solution of the Schrödinger equation in superposition with an Aharonov–Bohm field

A charged particle is considered in a complex external electromagnetic field. The field is a superposition of an Aharonov–Bohm field and some additional field. Here we describe all additional fields known up to the present time that allow exact solution of the Schr?dinger equation in a complex field.     

Monocyclic and Fused 4-Imino(4-Oxo)-1,3,2-Diazaphospholanes and - Phosphorinanes. Synthesis and Some Properties

Abstract

In contrast to the great variety of well known phosphorus heterocycles with exocyclic C=O double bond the number of ones containing exocyclic C=N bond is unusually modest. We elaborated the convenient method of preparation of various N,P,N-heterocycles with exocyclic C=N bond (1–4) from the readily available corresponding amino acid amidines and appropriated dichlorides or diamides of phosphorus (III) acids. Rings' 1–3 with P(III) are easily converted into (thio)phosphoryl derivatives, while the direct phosphorylation of amino amidines by RP(Y)Cl₂ is unusually ineffective. Tricycles 4 - derivatives of 2-(2-amino pheny1)imidazoline - mainly exist in the more conjugated hydrophosphazo tautomeric form 4b (>90 %).     

Diazoalkanes in the Reactions with Dialkyl (Thio)-Phosphites

Abstract

The photochemical, thermo-catalytical and thermal reactions of diazoalkanes with dialkyl (thio)phosphites were studied.

Thus, the photolysis of dimethyldiazomalonate and methyl-diazoacetate with dialkyl(thio)phosphites gives P-H insertion products only upon triplet-sensitized conditions (i), whereas diphenyldiazomethane gives P-H insertion products upon direct photolysis as well (ii). The investigation of 31 the reaction mechanism is based on CIDNP ³¹P method. The catalytical reactions (iii) are a convenient method of preparing (thio)phosphonates.