Computational study of reaction pathways in the course of interaction of deactivated silylenes with buta-1,3-diene

The PESs of systems including deactivated silylenes (SiHHal, SiHal₂, Hal = F, Cl, and 2-silaimidazol-2-ylidene, SiN₂H₂C₂H₂) and buta-1,3-diene have been studied using G3(MP2)//B3LYP method. Two major reaction channels, (2 + 1) and (4 + 1) cycloaddition reactions, leading to 2-vinylsiliranes and silacyclopent-3-enes, respectively, as well as [1,3]-sigmatropic rearrangements between 2-vinylsiliranes and the corresponding silacyclopent-3-enes, have been considered in detail. Reactivity of silylenes toward buta-1,3-diene decreases in the following series: SiHHal > SiHal₂ > SiN₂H₂C₂H₂, which is reflected in increase of the reaction barriers for both cycloaddition reactions and in decrease of exothermicity of the formation of the corresponding products. The (4 + 1) cycloaddition is preferable for SiHal₂ and SiN₂H₂C₂H₂ and can compete with (2 + 1) cycloaddition for SiHHal. [1,3]-Sigmatropic rearrangement is important for isomerization of 2-vinylsiliranes to the corresponding silacyclopent-3-enes for all systems studied, except the SiCl₂ system.     

The Scale-Adaptive Simulation Method for Unsteady Turbulent Flow Predictions. Part 2: Application to Complex Flows

The paper summarises the validation activity performed with the Scale-Adaptive Simulation turbulence model (SAS model) using the two commercial CFD solvers, ANSYS-FLUENT and ANSYS-CFX. Both the KSKL-SAS and the SST-SAS model variants have been tested, although most cases have been computed with the second. The turbulence-resolving capability of the SAS method has been validated with a representative set of test cases, covering both underlying generic flows as well as practical engineering applications. In addition to the purely aerodynamic flows with massive separation and heat transfer they include also such physical phenomena as turbulent combustion and aeroacoustics. The illustrating results show the potentials of the SAS approach for industrial flow simulations. Most of the test case simulations were conducted during the recent EU project “DESider”.     

Protected optical line coding based on multiple-valued logics

Multiple-valued logic functions given by the Allen-Givone algebra are proposed for use in optical nonquantum communication channels as tools for generating a set of secret keys of very high dimension.     

Pressure shaping of titanium nickelide upon heating under shear stress

A unidirectional variation of the pressure applied to Ti-Ni alloy was found to cause strains of different sign when the material temperature was changed in 10 K steps. The pressure dependence of twin yield stress was obtained. It is concluded that pressure may initiate twinning in crystals.     

Destruction of polymeric cobalt(ii) trimethylacetate. Synthesis and structures of new complexes Co9(μ3-OH)6(μ-OOCCMe3)12(OCMe2)4 and Co6(μ4-O)2(μ-OOCCMe3)10(η-HOOCCMe3)4

Russian Chemical Bulletin -     

On the Lagrange Problem on the Optimal Form for Circular Columns

A new approach to the classical Lagrange problem on the form of the strongest circular column of fixed volume and height clamped at both ends is proposed. The existence of the optimal column is proved and an algorithm for finding its design is given.__________Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 10, Suzdal Conference-4, 2003.An erratum to this article can be found at .