Numerical study of the influence of boundary conditions on the dynamic behavior of a cylindrical shell conveying a fluid

We consider a finite element algorithm intended to study the dynamic behavior of an elastic cylindrical shell filled with an immovable or flowing fluid. To describe the fluid, we use the perturbed velocity potential whose equations with the corresponding boundary conditions are solved by the Bubnov-Galerkin method. To describe the shell, we use the variation principle, which includes the linearized Bernoulli equation for calculating the hydrodynamic pressure acting on the shell on the side of the fluid. Solving the problem is reduced to calculating and analyzing the eigenvalues of the coupled system of equations obtained as a result of combining the equations for the perturbed velocity potential and the shell displacements. We consider several test problems in which, along with the comparison of the computational results with the earlier published experimental, analytic, and numerical data, we also study the dynamic behavior of the “shell-fluid” system for various boundary conditions for the perturbed velocity potential.     

Rare-earth metal 8-hydroxyquinolinate complexes as materials for organic light-emitting diodes

Rare-earth metal 8-hydroxyquinolinates (q) were studied as emission layers for organic light-emitting diodes. Compounds Dyq₃, Tbq₃, and Smq₃ possess weak electroluminescence due to the emission of the ligand, and the electroluminescence of Hoq₃, Tmq₃, and Ybq₃ is due to electronic transitions of the lanthanide ion. The best electroluminescence characteristics were demonstrated by Scq₃ and Yq₃. The power efficiency of the organic light emitter based on ITO/TPD/Scq₃/Yb (ITO is tin-alloyed indium oxide, TPD is N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine) is 2.6 lm W⁻¹ at a luminance of the device of 300 cd m⁻².     

Investigations in the field of depsipeptides Communication 44. Mass spectrometric study of cyclodidepsipeptides-2,5-diketomorpholines

Conclusions The fragmentation of cyclodidepsipeptides during electron impact was investigated. The nature of the hydroxy and amino acid residues contained in the 2,5-diketomorpholines can be established on the basis of the mass spectra.For the preceding Communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1539–1543, September, 1966.     

Preparation of isomeric 1,3- and 1,5- (o-phenylene)-hexamethylcyclotetrasiloxanes and investigation of their spectral characteristics

Workup of the mixture of products of pyrolysis of cyclotetrasiloxane (Me₂SiO)₂(MePhSiO)₂ yielded 1,3- (I) and 1,5-(o-phenylene)cyclosiloxane (II), the structures of which were established on the basis of data from their IR, PMR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 24–25, January, 1978.     

Reactions of neodymium(ii), dysprosium(ii), and thulium(ii) diiodides with cyclopentadiene. Molecular structures of complexes CpTmI2(THF)3 and [NdI2(THF)5]+[NdI4(THF)2]–

The reactions of LnI₂ (Ln = Nd (1) or Dy (2)) with cyclopentadiene (CpH) in THF at 0 °C afforded the CpLnI₂(THF)₃ complexes in 65—67% yields. The reaction of thulium diiodide (3) with an excess of CpH at 60 °C produced CpTmI₂(THF)₃, Cp₂TmI(THF)₂, and TmI₃(THF)₃ in 21, 58, and 63% yields, respectively. The reactions of 1 and 2 with pentamethylcyclopentadiene (Cp*H) in THF were accompanied by disproportionation giving rise to the Cp*₂LnI(THF)₂ and LnI₃(THF) _x complexes. Neodymium triiodide was isolated in the ionic form [NdI₂(THF)₅]⁺[NdI₄(THF)₂]^–. Its structure and the structure of CpTmI₂(THF)₃ were established by X-ray diffraction analysis.     

Mass-spectrometer investigation of 3, 6-dialkyl-2, 5-diketopiperazines

Analysis of mass-spectra of various 2, 5-diketopiperazines gives the basic fragmentation rules for their molecular ions, and the effects of nature and positions of substituents on the process.Mass-spectrometry Laboratory of the Institute of the Chemistry of Natural Compounds.Antibiotics Chemistry Laboratory of the Institute of the Chemistry of Natural Compounds.     

Stereoselective formation of ansa-metallocenes in reactions of radical-anionic salts of acenaphthylene with lanthanide and calcium halides

ansa-Metallocenes (⁵:⁵-C₂₄H₁₆)M(THF)₂ (M = Sm (1), Yb (2), Ca (3)) and (⁵:⁵-C₂₄H₁₆)MI(THF) (M = Dy (8), Er (9), Tm (10), Lu (11)) were prepared in 50—90% yields by the in situ reactions of two equivalents of potassium acenaphthylenide K⁺C₁₂H₈ ^– with MI₂ or MI₃, respectively. Complexes 2 and 3 were also obtained by direct reduction of acenaphthylene with ytterbium and calcium naphthalenides, respectively. An ESR signal of the acenaphthylene radical anion, which was observed upon dissolution of compound 2 in THF, indicates that the [C₂₄H₁₆]^2– ansa-ligand dissociated into two [C₁₂H₈]^·– radical anions. Hydrolysis of complex 2 in benzene afforded 1,1",3,3"-tetrahydro-3,3"-biacenaphthylene (4) and 3,3",4,4"-tetrahydro-3,3"-biacenaphthylene (5). The reaction of complex 2 with ZrCl₄ and the reaction of compound 3 with Me₃SiCl proceeded with the cleavage of the C—C bond between two acenaphthylene fragments of the [C₂₄H₁₆]^2– ansa-ligand to produce (²-C₁₂H₈)ZrCl₂(THF)₃ (6) and bis(trimethylsilyl)acenaphthene (Me₃Si)₂C₁₂H₈ (7), respectively. Compounds 1—3, 6, 7, and 11 were characterized by ¹H and ¹³C NMR spectroscopy. The temperature dependence of the ¹H NMR spectrum of compound 11 in tetrahydrofuran is indicative of the dynamic exchange of the solvent molecules in the coordination sphere of the Lu atom. After cooling of the solution to 210 K, the dynamic process was terminated as evidenced by the nonequivalence of the ¹H signals of two acenaphthylene fragments. According to the X-ray diffraction data for complex 11, dimerization of two acenaphthylene radical anions at the Lu atom gave rise to the rac-ansa-metallocene structure. In compound 11, the Lu atom is ⁵-coordinated by two five-membered rings of the acenaphthylene ligands and also by the I atom and the THF molecule. The coordination environment about the Lu atom is a distorted tetrahedron. The average distance between the lutetium atom and the carbon atoms of the five-membered rings is 2.623 .     

Reduction of 2,5-di-tert-butylcyclopentadienone and pyridine with thulium diiodide. Structures of the complexes TmI2(THF)2[η5-But2C5H2O]TmI2(THF)3 and [TmI2(C5H5N)4]2(μ2-N2C10H10)

Reduction of 2,5-di-tert-butylcyclopentadienone with two equivalents of thulium diiodide in tetrahydrofuran afforded the binuclear thulium(iii) complex with the cyclopentadienyl oxide ligand, viz., TmI₂(THF)₂[⁵-Bu^t ₂C₅H₂O]TmI₂(THF)₃ (1). Shielding of the carbonyl carbon atom with two tert-butyl substituents prevents pinacolization of the ketyl radical anions that formed upon one-electron reduction of cyclopentadienone. The reaction of thulium diiodide with an excess of pyridine in tetrahydrofuran gave a product of reductive coupling of two pyridine radical anions, viz., [TmI₂(C₅H₅N)₄]₂(₂-N₂C₁₀H₁₀) (2). The structures of complexes 1 and 2 were established by single-crystal X-ray diffraction analysis.     

The reactions of phenylacetylene with naphthalene complexes of europium and ytterbium. Molecular structure of [IYbC≡CPh(DME)2]2

Reactions of naphthaleneeuropium and naphthaleneytterbium, C₁₀H₈Ln(DME) (Ln = Eu or Yb), with phenylacetylene are accompanied by the formation of the C-C bond and yield the complexes of composition Ph₂C₄H₂Ln(DME)₂. Hydrolysis of the Ph₂C₄H₂Ln(DME)₂ complexes affords a mixture of isomers of 1,4-diphenyl-1,3-butadiene. Reactions of C₁₀H₈[LnI(DME)₂]₂ with PhCCH yield mixed iodine-ethynyl complexes [ILn(-CCPh)(DME)₂]₂. According to the data of X-ray diffraction analysis, the ytterbium complex consists of two YbI(DME)₂ units bonded through two bridging CCPh groups. The crystals of this complex belong to the space groupP2₁/c. The central cyclic Yb-C-Yb-C fragment is planar; the C(I)-Yb(I)-C(I) angle is 86.4(3)°. The Yb-C bond lengths are 2.584(8) and 2.603(9) Å.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2101–2104, August, 1996.