Kinetic rules of precipitation of thin films of titanium dioxide from the gas phase containing titanium tetraisopropylate

Precipitation of titanium dioxide layers from the gas phase in the reaction system containing titanium tetraisopropylate and oxygen at the total pressure 1 kPa is studied. It is shown that in the range of 300–500°C the precipitation proceeds in the kinetic regime and is accompanied by the formation of layers of monotonous thickness containing nanocrystalline phases of anatase and rutile. In the temperature range 300–350°C the activation energy value was 92.7 kJ mol^?1, and at higher temperatures (up to 500°C) it decreased to 17.5 kJ mol^?1. The increase in the precipitation temperature caused the increase in relative amount of rutile in the precipitated layers.     

Dinuclear and polynuclear transition metal complexes with macrocyclic ligands. 6. New dinuclear copper(ii) complexes with macrocyclic Schiff bases derived from 4-tert-butyl-2,6-diformylphenol

New dinuclear complexes containing Cu^II atoms in the cavity of a macrocyclic Schiff base were prepared by template condensation of 4-tert-butyl-2,6-diformylphenol with 1,3-diaminopropane in the presence of Cu^II trimethylacetate and chloride as well as by extra-ligand exchange. The mononuclear Cu^II complex with two 1,3-diaminopropane molecules can serve as an intermediate in this template synthesis. The reaction of Cu^II trimethylacetate with the unsymmetrical macrocyclic Schiff base synthesized earlier afforded a new dinuclear copper(ii) complex with the amine and imine nitrogen atoms in the coordination sphere. The structures of the new complexes were established by X-ray diffraction analysis and studied by the density functional theory (gradient-corrected PBE functional, TZ2p basis set).     

Visualization of four limit cycles of two-dimensional quadratic systems in the parameter space

This paper deals with the visualization of a domain that contains four limit cycles for quadratic dynamical systems of first-order differential equations with real coefficients. The visualization of the domain is carried out in the three-dimensional space of coefficients corresponding to the nonlinear part of the quadratic system. Theoretical and practical aspects of the numerical solution of the Cauchy problem for unstable systems are discussed.     

Particle-yield modification in jetlike azimuthal dihadron correlations in Pb-Pb collisions at √s(NN)=2.76 TeV

The yield of charged particles associated with high-p(t) trigger particles (83 GeV/c on the away side drops to about 60% of that observed in pp collisions, while on the near side a moderate enhancement of 20%-30% is found.     

Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying W Bosons

This Letter presents a search for pair production of heavy down-type quarks decaying via b^{'}→Wt in the lepton+jets channel, as b^{'}b[over ˉ]^{'}→W^{-}tW^{+}t[over ˉ]→bb[over ˉ]W^{+}W^{-}W^{+}W^{-}→l^{±}νbb[over ˉ]qq[over ˉ]qq[over ˉ]qq[over ˉ]. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04 fb^{-1} from pp collisions at sqrt[s]=7 TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480?GeV can be excluded at the 95% confidence level.     

On computer implementation of the Hertz elastic contact model and its simplifications

The paper is concerned with an elastic contact model of rigid bodies which is developed in the framework of the Hertz model. For this new model, we suggest more effective algorithms with reduced computational time. We also present an algorithm for representation of the geometry of the contacting surfaces in the local contact coordinate system. This coordinate system tracks permanently the surfaces of the bodies, which are able to contact. An approach to computation of the normal elastic force is presented. It is based on the reduction to a single transcendental scalar equation that includes the complete elliptic integrals of the first and second kinds. The computational time in the Hertz-model simulation was considerably reduced due to the use of the differential technique for computation of the complete elliptic integrals and due to the replacement of the implicit transcendental equation by a differential one. Using the classic solution of the Hertz contact problem, we then present an invariant form for the force function, which depends on the geometric properties of the intersection of the undeformed volumes occupied with the rigid bodies (so-called volumetric model). The reduced expression for the force function obtained is shown to be different from that accepted in the classic contact theory hypotheses. Our expression has been tested in several examples dealing with bodies that contact elastically including Hertz’s classical model. In the context of the Hertz contact problem, an approximate model for computation the resulting wrench of the dry friction tangent forces is set up. The wrench consists of the total friction force and the drilling friction torque. The approach under consideration naturally extends the contact model constructed earlier. The dry friction forces and torque are integrated over the contact elliptic spot. Generally an analytic computation of the integrals mentioned is bulk and cumbersome leading to decades of terms that include rational functions depending on complete elliptic integrals. To be able to implement a fast computer model of elastically contacting bodies, one should first set up an approximate model in the way initially proposed by Contensou. To verify the model developed, we have used results obtained by several authors. First we test our method on the Tippe-Top dynamic model. Simulations show that the top’s evolution can be verified with a high quality compared with the use of the theory of set-valued functions. In addition, the ball bearing dynamic model has been also used for a detailed verification of different approaches to the computation of tangent forces. Then the friction model of the regularized Coulomb type and the approximate Contensou one, each embedded into the whole bearing dynamic model, were thoroughly tested and compared. It turned out that the simplified Contensou approach provides a computer model that runs even faster compared with the case of the point contact. In addition, the volumetric model demonstrated a reliable behavior and an acceptable accuracy.     

Reaction of chlorine with platinum(IV) triamine containing N,N-dimethylethylenediamine. The crystal structure of [Pt{(CH3)2N(CH2)2NH2}PyCl3]Cl·H2O[Pt{(CH3)2N(CH2)2NCl}PyCl3], and [Pt{(CH3)2N(CH2)2NH2}PyCl4]

The Platinum(II) diamine with N,N-dimethylethylenediamine (N,N-dimeEn) [Pt{(CH₃)₂N(CH₂)₂NH₂}Cl₂] (I) was synthesized. The reaction of the diamine with pyridine gave Pt(II) tetramine [Pt{(CH₃)₂N(CH₂)₂NH₂}Py₂]Cl₂ (II), which was oxidized with chlorine to give Pt(IV) triamine Pt{[(CH₃)₂N(CH₂)₂}PyCl₃]Cl · H₂O (III). The reaction of III with chlorine (chloroamidation) yielded chloroimide [Pt{(CH₃)₂N(CH₂)₂NCl}PyCl₃] (IV). The IR spectra of complexes I–IV and UV/Vis spectra of III and IV were studied. X-Ray diffraction analysis was performed for III (monoclinic crystals, space group P2₁/c, a = 7.7437(6), b = 8.1100(7), c = 28.52992(2) Å, β = 93.7280(10)°, Z = 4, R _hkl = 0.0420) and IV (orthorhombic crystals, space group Pna2₁, a = 15.7825(12), b = 7.4447(6), c = 12.3099(6) Å, Z = 4, R _hkl = 0.0539). During oxidation of Pt(II) tetramine with chlorine, the pyridine molecule is removed from the cis position relative to the (CH₃)₂N group (trans position relative to the NH₂ group) of N,N-dimethylethylenediamine. The reaction of chloroimide complex IV with concentrated HCl (dechloroamidation) at 20°C afforded the initial complex III; that at 100°C, gave triamine III together with Pt(IV) diamine [Pt(N,N-dimeEn)Cl₄] (V) (monoclinic crystals, space group P2₁/n, a = 7.1278(5), b = 11.5384(8), c = 12.7501(9) Å, β = 93.23(10)°, Z = 4, R _hkl = 0.0239).     

Low-energy electron diffraction and induced damage in hydrated DNA

Elastic scattering of 5-30 eV electrons within the B-DNA 5'-CCGGCGCCGG-3' and A-DNA 5'-CGCGAATTCGCG-3' DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30 eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18, and 22-28 eV for the B-DNA target and at 7-11, 12-18, and 18-25 eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 A spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H2O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks.     

Homogeneous oxidation of hydrogen selenide with ozone in an argon-oxygen medium

Homogeneous oxidation of hydrogen selenide with ozone present in deficiency was studied. One of the reaction products is elemental selenium Se₈, which can be formed by multistep radical-chain polycondensation of hydrogen selenide. One mole of ozone is consumed per mole of hydrogen selenide. The observed rate constant of the reaction of hydrogen selenide with ozone at 20 ± 1°C is no less than (1.9 ± 0.2) × 10⁵ l mol^?1 s^?1.