Design of Steel-Composite Multirim Cylindrical Flywheels Manufactured by Winding with High Tensioning and in situ Curing. 2. Numerical Analysis

The possibility of using forced winding coupled with in situ curing to increase the energy storage capacity of hybrid steel-composite cylindrical flywheels is estimated and analyzed. Stress states for given loading conditions in two- and three-layered compound cylinders made from steel and four different types of unidirectional composites are calculated. For each of these combinations, optimum dimensions and the energy storage capacity of the flywheels are found.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 3, pp. 351–372, May–June, 2005.     

Asymptotic Analysis of Reacting Materials with Saturated Explosion. II. High-Frequency Waves

The interaction of small-scale material inhomogeneities with high-frequency acoustic waves is known to have a prominent role in accelerating the heat-release rate in liquid and solid explosive materials. In the present paper, simplified asymptotic equations are studied which incorporate the above interaction, and which include reactant depletion at leading order. Because fuel may be completely exhausted, singularities do not always form in the model equations; it is conjectured that when a singularity does form, the material has initiated. The detailed mechanisms by which shock formation and resonant wave interaction can either enhance or retard reaction are explored. In a realistic model for inhomogeneous condensed-phase reaction, with pressure-dependent reaction rate and nonconstant initial fuel concentration, initiation of the material depends on correct placement of the fuel relative to the acoustic waves.     

Structural and dielectric properties of La- and Ti-modified K0.5Na0.5NbO3 ceramics

We report the results of studies of rectifying behavior, positive magneoresistance (MR), the charge-transport mechanism and the effect of an electric field on a ZnO (n)/La_0.5Pr_0.2Sr_0.3MnO₃ (LPSMO) (p)/SrNb_0.002Ti_0.998O₃ (SNTO) (n) heterostructure comprising two p–n junctions fabricated using the pulsed laser deposition technique. The heterostructure exhibits rectifying behavior over a wide temperature and field range having hysteresis in I–V behavior (forward bias) due to the tunneling of charge carriers. It is also observed that, depending on the nature of the electric field bias to n-type ZnO and SNTO, the junction resistance becomes modified, which has been explained on the basis of spin injection in the heterostructure. The observation of unconventional positive MR at room temperature has been justified on the basis of interface effects and the reduction in barrier height obtained using fitting of the I–V data by a thermionic emission model.     

Melting of "porous" vortex matter

Bitter decoration and magneto-optical studies reveal that in heavy-ion irradiated superconductors, a "porous" vortex matter is formed when vortices outnumber columnar defects. In this state ordered vortex crystallites are embedded in the "pores" of a rigid matrix of vortices pinned on columnar defects. The crystallites melt through a first-order transition while the matrix remains solid. The melting temperature increases with density of columnar defects and eventually turns into a continuous transition. At high temperatures a sharp kink in the melting line is found, signaling an abrupt change from crystallite melting to melting of the rigid matrix.     

Time-evolution of quantum systems via a complex nonlinear Riccati equation. I. Conservative systems with time-independent Hamiltonian

The sensitivity of the evolution of quantum uncertainties to the choice of the initial conditions is shown via a complex nonlinear Riccati equation leading to a reformulation of quantum dynamics. This sensitivity is demonstrated for systems with exact analytic solutions with the form of Gaussian wave packets. In particular, one-dimensional conservative systems with at most quadratic Hamiltonians are studied.     

Gravity Waves in a Channel with a Rough Bottom

We derive effective equations for the surface elevation of gravity waves in a shallow channel with a rough bottom.     

Features of the electrochemical lithium insertion into monophosphate tungsten bronzes (PO2)4(WO3)2m (m=9 and 10)

Electrochemical lithium insertion into (PO₂)₄(WO₃)_2m, where m=9 and 10, has allowed the determination of several phases Li_x(PO₂)₄(WO₃)_2m between 3.4 and 0.01 V vs Li⁺/Li⁰. After the first cycle the electrochemical system was unable to maintain the high specific capacity of the cells (540 Ah/kg) due to irreversible processes. Nevertheless at high voltage values, above 1.4 V vs Li⁺/Li⁰, the lithium insertion proceeded through a reversible mechanism. By means of X-ray diffraction experiments we have detected the nature of different phases Li_x(PO₂)₄(WO₃)_2m formed and we have established a correlation with the reversible/irreversible processes detected during the electrochemical insertion.     

Rectangular to hexagonal columnar phase transition exhibited by a biforked mesogen

We present the structural study of a biforked compound exhibiting a Col_r-Col_h phase transition. This study was performed by means of DSC, optical microscopy, X-ray diffraction, dilatometry and molecular modelling. The molecular packing within the two columnar mesophases of this compound is discussed. For the first time, it is shown that the clusters of adjacent molecules which form the elementary section of a column are tilted with respect to the columnar axis in the rectangular mesophase. From the whole set of experimental data, the number of molecules in a columnar section is found to be about 5 in the rectangular mesophase, and 4 in the hexagonal one. The transition between the two columnar mesophases is discussed with respect to its slow kinetics. Received 1st October 2002 Published online: 16 April 2003 RID="a" ID="a"e-mail: ribeiro@cii.fc.ul.pt RID="b" ID="b"UMR 7504     

Multiresonance modes in sine–Gordon brane models

In this work, we study the localization of the vector gauge field in two five-dimensional braneworlds generated by scalar fields coupled to gravity. The sine–Gordon like potentials are employed to produce different thick brane setups. A zero mode localized is obtained, and we show the existence of reverberations with the wave solutions indicating a quasi-localized massive mode. More interesting results are achieved when we propose a double sine–Gordon potential to the scalar field. The resulting thick brane shows a more detailed topology with the presence of an internal structure composed by two kinks. The massive spectrum of the gauge field is revalued on this scenario revealing the existence of various resonant modes. Furthermore, we compute the corrections to Coulomb law coming from these massive KK vector modes in these thick scenarios, which is concluded that the dilaton parameter regulates these corrections.     

Design,synthesis, molecular docking and in vitro evaluation of benzothiazole derivatives as 11β-hydroxysteroid dehydrogenase type 1 inhibitors

Molecular Diversity - 11-Beta hydroxysteroid dehydrogenase type 1 (11β-HSD1) regulates cortisol levels mainly in adipose, hepatic and brain tissues. There is a relationship between the high...