Kinetic studies of laser-induced synthesis of thin vanadium pentoxide films

The kinetics of Ar⁺ laser-induced oxidation of 100 nm thick vanadium films on glass substrates is followed by measuring time-dependent changes in reflected and transmitted intensity of a He-Ne probe beam. The growth rate of the vanadium pentoxide layer increases with increasing laser powerP as = ₀ exp(-a/P). At power densities above kW/cm² vanadium pentoxide crystallizes from the melt.     

Lie-admissible structures on Witt type algebras

In this paper we study Lie-admissible structures on Witt type algebras. Witt type algebras are Γ$\Gamma$-graded Lie algebras (where Γ$\Gamma$ is an abelian group) which generalize the Witt algebra. We give all third power-associative and flexible Lie-admissible structures on these algebras. In particular we generalize some results on the Witt algebra. After describing the second scalar cohomology group of Witt type algebras, we investigate third power-associative and flexible Lie-admissible structures on the central extension of some Witt type algebras. Finally we study a left-symmetric structure induced by a symplectic form for some Witt type algebras.     

Integrable Hamiltonian systems related to the Hilbert–Schmidt ideal

By the application of the coinduction method as well as the Magri method to the ideal of real Hilbert–Schmidt operators we construct the hierarchies of integrable Hamiltonian systems on Banach Lie–Poisson spaces which consist of such types of operators. We also discuss their algebraic and analytic properties and solve them in dimensions, N=2,3,4$N=2,3,4$.     

The Bogoliubov inner product in quantum statistics

A natural Riemannian geometry is defined on the state space of a finite quantum system by means of the Bogoliubov scalar product which is infinitesimally induced by the (nonsymmetric) relative entropy functional. The basic geometrical quantities, including sectional curvatures, are computed for a two-level quantum system. It is found that the real density matrices form a totally geodesic submanifold and the von Neumann entropy is a monotone function of the scalar curvature. Furthermore, we establish information inequalities extending the Cramér-Rao inequality of classical statistics. These are based on a very general new form of the logarithmic derivative.This work was supported by the Hungarian National Foundation for Scientific Research, grant No. 1900. Authors' e-mail addresses are: H1128PET@ella.hu and TOTH@zodiac.rutgers.edu.     

A noncommutative geometric approach to left-right symmetric weak interactions

By combining the generalized exterior algebra of forms over a noncommutative algebra with the gauging of discrete directions and the associated Higgs fields, we consider the construction of the bosonic sector of left-right symmetric models of the form SU(2) _L SU(2) _R U(1). We see that within this formalism maximal use can be made of the gauge connection associated with the noncommutative graded algebra.     

Quasi-classical limit of Toda hierarchy andW-infinity symmetries

Previous results on quasi-classical limit of the KP hierarchy and itsW-infinity symmetries are extended to the Toda hierarchy. The Planck constant now emerges as the spacing unit of difference operators in the Lax formalism. Basic notions, such as dressing operators, Baker-Akhiezer functions, and tau function, are redefined.W _{1 +} symmetries of the Toda hierarchy are realized by suitable rescaling of the Date-Jimbo-Kashiara-Miwa vertex operators. These symmetries are contracted tow _{1 +} symmetries of the dispersionless hierarchy through their action on the tau function.     

Are the New Physics Contributions from the Left-Right Symmetric Model Important for the Indirect CP Violation in the Neutral B Mesons?

No Heading Several works analyzing the new physics contributions from the Left-Right Symmetric Model to the CP violation phenomena in the neutral B mesons can be found in the literature. These works exhibit interesting and experimentally sensible deviations from the Standard Model predictions but at the expense of considering a low right scale υ_R around 1 TeV. However, when we stick to the more conservative estimates for υ_R, which say that it must be at least 10⁷ GeV, no experimentally sensible deviations from the Standard Model appear for indirect CP violation. This estimate for υ_R arises when the generation of neutrino masses is considered. In spite of the fact that this scenario is much less interesting and says nothing new about both the CP violation phenomenon and the structure of the Left-Right Symmetric Model, this possibility must be taken into account for the sake of completeness and when considering the see-saw mechanism that provides masses to the neutrino sector. ¹ Associate researcher of the Centro Internacional de Física, Ciudad Universitaria, Bogotá D.C., Colombia.     

Low temperature structural phase transition in hafnium and zirconium tetrafluoride trihydrates

From time-differential perturbed angular correlation (TDPAC) measurements, the monoclinic and triclinic crystal structures in hafnium and zirconium tetrafluoride trihydrates are found to be present simultaneously in both the compounds. From previous TDPAC and XRD investigations, a monoclinic crystal structure for HfF₄·3H₂O but, for its analogues zirconium compound, a triclinic structure was reported. Contrary to earlier reports, the triclinic fraction in HfF₄·3H₂O is found to be maximum (80%) at room temperature. In fact, the triclinic crystal structure of HfF₄·3H₂O is reported here which was not known prior to this report. In ZrF₄·3H₂O, a strong signal (80–90%) for the triclinic structure is found at room temperature while the monoclinic fraction appears as a weak signal (10–15%). Structural phase transitions in these trihydrate compounds have been observed in the temperature range 298–333 K.     

Low-density carbon material modified with pyrolytic carbon

Here we report a physicochemical investigation of low-density carbon materials modified with pyrolytic carbon (PC). Exfoliated graphite (EG) obtained by nitrate expandable graphite thermal destruction was pressed into low-density graphite materials (LDGMs) with densities of 0.045-0.50 g/cm³ and saturated with PC by impact CVI technique. LDGM infiltration with PC leads to sample weight and density growth. The amount of deposited PC strictly depends on synthesis conditions. The maximum surface and volume deposition of PC occurred for samples with density of 0.05 g/cm³. XRD, Raman spectroscopy and scanning electron microscopy revealed that the deposited PC is of smooth laminar (SL) type. Composite thermal conductivity is about 2-3.5 Wt/m K.