Continuation of the exponentially small transversality for the splitting of separatrices to a whiskered torus with silver ratio

We study the exponentially small splitting of invariant manifolds of whiskered (hyperbolic) tori with two fast frequencies in nearly-integrable Hamiltonian systems whose hyperbolic part is given by a pendulum. We consider a torus whose frequency ratio is the silver number $\Omega=\sqrt{2}-1$. We show that the Poincar\'e-Melnikov method can be applied to establish the existence of 4 transverse homoclinic orbits to the whiskered torus, and provide asymptotic estimates for the tranversality of the splitting whose dependence on the perturbation parameter $\varepsilon$ satisfies a periodicity property. We also prove the continuation of the transversality of the homoclinic orbits for all the sufficiently small values of $\varepsilon$, generalizing the results previously known for the golden number.Comment: 17 pages, 2 figure

Characterization of the binding sites of the anticancer ruthenium(III) complexes KP1019 and KP1339 on human serum albumin via competition studies

Indazolium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (KP1019) and its Na+ analogue (KP1339) are two of the most prominent non-platinum antitumor metal complexes currently undergoing clinical trials. After intravenous administration, they are known to bind to human serum albumin (HSA) in a noncovalent manner. To elucidate their HSA binding sites, displacement reactions with the established site markers warfarin and dansylglycine as well as bilirubin were monitored by spectrofluorimetry, ultrafiltration-UV-vis spectrophotometry, and/or capillary zone electrophoresis. Conditional stability constants for the binding of KP1019 and KP1339 to sites I and II of HSA were determined, indicating that both Ru(III) compounds bind to both sites with moderately strong affinity (log K (1)' = 5.3-5.8). No preference for either binding site was found, and similar results were obtained for both metal complexes, demonstrating low influence of the counter ion on the binding event

Magnetic flux annihilation waves in inhomogeneous high-temperature superconductors

The process of magnetic field penetration into polycrystalline high-T-c superconductors of the YBa2Cu3O7 - x and Bi2Sr2Ca2Cu3O10 - x systems has been studied using traditional magnetooptical methods and scanning Hall probe microscopy. It is established that remagnetization of a sample is accompanied by the formation and propagation of a stationary magnetic flux annihilation (MFA) wave. Spatial inhomogeneity of the superconductors studied is manifested by a curvature of the MFA wave front. (C) 2004 MAIK "Nauka / Interperiodica"

Substrate Influence on Dendritic Flux Instability in YBCO Thin Films

We have investigated the effect of substrate thermal conductivity on dendritic flux formation in thin superconducting YBa2Cu3O7-x films grown on yttrium-stabilized zirconia, SrTiO3, MgO, and sapphire, exploiting a recently developed ultra-fast magneto-optical imaging system and its ultra-fast field ramp (3 kT/s). Dendritic flux formation triggered solely by rapid ramping of the external field is reported for the first time in YBCO on yttrium-stabilized zirconia, the substrate with the lowest thermal conductivity. For the other substrates, the dendritic instability could be generated only after introducing an artificial defect at the edge, enhancing the local induction. We find that the upper temperature threshold for the appearance of dendrites depends on the thermal conductivity of the substrate