On approximation of functions in terms of Φ-variation

Получен аналог теоре мы Джексона о приближ ении полиномами в метрике Ф-вариации; для некото рых классов функций (в ыпуклых, конечной вариации, с заданным модулем неп рерывности) установл ено соотношение типа сла бой эквивалентности, которое связывает ме жду собой рациональн ые аппроксимации, в этой и равномерной метриках Даны оценкиε-энтропи и в метрике Ф-вариации классов функций с заданным мо дулем Ф-абсолютной непреры вности и с заданным мо дулем непрерывности.     

Investigation of filtration convection in a near-critical Van-der-Waals gas for substantial temperature differences

The qualitative mechanisms of stationary filtration convection in a near-critical Van-der-Waals gas with substantial temperature variations are investigated. The object of the study is a thin porous ring in a vertical heat-conducting plane, saturated with the gas. An adequate mathematical model, based on the averaging of the two-dimensional equations over the ring thickness, is proposed. The dependence of natural-convection characteristics on the non-Boussinesq parameters (compressibility criteria, temperature difference, and proximity to the critical point) is found. The limits of applicability of the previously known regularities related to the conditions of onset and the properties of stationary convection are discussed.     

Efficient halogenation of unsaturated organoaluminum compounds with sulfonyl halides

Alkenylalumanes prepared by carbo-or cycloalumination of substituted acetylenes reacted with an equivalent amount of sulfonyl halide (MsCl, TsCl, PhSO₂Cl, MsBr) in methylene chloride or hexane at room temperature to produce alkenyl halides in high yields. Electron-donor solvents such as diethyl ether or tetrahydrofuran inhibited the halogenation process. β-Substituted vinylalumanes generated by hydroalumination of substituted acetylenes failed to react with sulfonyl halides.     

Synthesis and Investigation of Piezophotocatalytic Properties of Polyvinylidene Fluoride Nanofibers Modified with Titanium Dioxide

Moscow University Chemistry Bulletin - A piezoactive nanofiber composite PVDF film with TiO2 nanoparticles included in it was synthesized by electrospinning. The composition, morphology and...     

Investigation of the critical properties of the frustrated Heisenberg model on a triangular lattice by the Monte Carlo method

The critical properties of the 3D frustrated antiferromagnetic Heisenberg model on a triangular lattice have been investigated by the replica Monte Carlo method. All main magnetic and chiral critical indices were calculated using the finite-size scaling theory. It is found that the class of universality of the critical behavior of the model studied depends on the type of interplane exchange interaction.     

Representation of the space of polyanalytic functions as a direct sum of orthogonal subspaces. Application to rational approximations

Suppose thatD={z:|z|<1}, L ₂ (D) is the space of functions square-integrable over area inD,A _k (D) is the set of allk-analytic functions inD, (A ₁ (D)=A(D) is the set of all analytic functions inD),A _k L ₂ (D)=L ₂ (D)∩A _k (D),A ₁ L ₂ (D)=AL ₂ (D),

Preparation of 20-hydroxyecdysone-22-benzoate

20-Hydroxyecdysone-22-benzoate was for the first time synthesized from 20-hydroxyecdysone.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 401–403, September–October, 2004.