Inorganic Sol-Gel Preparation of Medium Sized Microparticles of Li2TiO3 from TiCl4 as Tritium Breeding Material for Fusion Reactors

Microspheres of Li₂TiO₃ were fabricated by a classical, inorganic sol-gel process from commercially available TiCl₄. Elaborated process consists of the following main steps: (1) dissolving of TiCl₄ in concentrated aqueous HCl and addition of LiOH; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of water with partially dehydrated EH; (4) impregnation of gel to Li:Ti molar ratio MR = 2; (5) thermal treatment at 1200°C in order to receive chloride free product. This temperature can be significantly lowered (to 750°C) by dechlorination starting solution TiCl₄ by chemical treatment of the with nitric acid to form of nitrate-stabilized titania sols. Tritium release from sol-gel made Li₂TiO₃ microspheres were found very close to that observed for other traditional materials, however for the first sample process starts slightly earlier.     

Cross sections for multi-particle final states at a linear collider

In this paper total cross sections for signals and backgrounds of top- and Higgs-production channels in e ⁺ e^- collisions at a future linear collider are presented. All channels considered are characterized by the emergence of six-particle final states. The calculation takes into account the full set of tree-level amplitudes in each process. Two multi-purpose parton level generators, HELAC/PHEGAS and AMEGIC + + , are used, and their results are found to be in perfect agreement.Received: 26 November 2003, Revised: 15 January 2004, Published online: 3 March 2004     

Click chemistry in materials synthesis. III. Metal‐adhesive polymers from Cu(I)‐catalyzed azide–alkyne cycloaddition

1,2,3‐Triazole‐based polymers generated from the Cu(I)‐catalyzed cycloaddition between multivalent azides and acetylenes are effective adhesive materials for metal surfaces. The adhesive capacities of candidate mixtures of azide and alkyne components were measured by a modified peel test, using a customized adhesive tester. A particularly effective tetravalent alkyne and trivalent azide combination was identified, giving exceptional strength that matches or exceeds the best commercial formulations. The addition of Cu catalyst was found to be important for the synthesis of stronger adhesive polymers when cured at room temperature. Heating also accelerated curing rates, but the maximum adhesive strengths achieved at both room temperature and high temperature were the same, suggesting that crosslinking reaches the same advanced point in all cases. Polytriazoles also form adhesives to aluminum, but copper is bound more effectively, presumably because active Cu(I) ions may be leached from the surface to promote crosslinking and adhesion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5182–5189, 2007     

Stark structure of the Yb3+ ion levels in (YbxY1?x)2Ti2O7 and the crystal field in rare-earth titanates with a pyrochlore structure

The absorption spectra of Yb₂Ti₂O₇ single crystals and the luminescence and luminescence excitation spectra of Y₂Ti₂O₇: Yb (1%) polycrystals were studied in the temperature range 4.2–300 K. The spectra were analyzed in terms of the crystal-field theory and the exchange-charge model. Based on the set of crystal-field parameters found for Yb₂Ti₂O₇, analogous sets of parameters were determined for other rare-earth titanates and proved to be in reasonable agreement with all available experimental data. __________ Translated from Fizika Tverdogo Tela, Vol. 47, No. 8, 2005, pp. 1376–1380. Original Russian Text Copyright ? 2005 by Klimin, Popova, Chukalina, Malkin, Zakirov, Antic-Fidancev, Goldner, Aschehoug, Dhalenne.     

Homothetic self-similar solutions of three-dimensional Brans-Dicke gravity

All homothetic self-similar solutions of the Brans-Dicke scalar field in three-dimensional spacetime with circular symmetry are found in closed form.     

Thermodynamic modeling of the behavior of silicon oxide and nitride precursors in the preparation of dielectric layers

The thermodynamic properties of several silicon-containing derivatives of asymmetric dimethylhydrazine were estimated by comparative methods. The CVD diagrams of the deposition of silicon nitride and dioxide from gas media containing these reagents were constructed.     

Dynamics of moving interacting atoms in a laser radiation field and optical size resonances

The forces acting on interacting moving atoms exposed to resonant laser radiation are calculated. It is shown that the forces acting on the atoms include the radiation pressure forces as well as the external and internal bias forces. The dependences of the forces on the atomic spacing, polarization, and laser radiation frequency are given. It is found that the internal bias force associated with the interaction of atomic dipoles via the reemitted field may play an important role in the dynamics of dense atomic ensembles in a light field. It is shown that optical size resonances appear in the system of interacting atoms at frequencies differing substantially from transition frequencies in the spectrum of atoms. It is noted that optical size resonances as well as the Doppler frequency shift in the spectrum of interacting atoms play a significant role in the processes of laser-radiation-controlled motion of the atoms.