Possible d+id scenario in La_{2-x}Sr_{x}CuO_4 by point-contact measurements

We analyze the results of point-contact measurements in La_{2-x}Sr_{x}CuO_{4} (LSCO) previously reported as a clear evidence of the separation between gap and pseudogap in this copper oxide. Here we show that, in addition to this, the conductance curves of our point-contact junctions -- showing clear Andreev reflection features -- can be interpreted as supporting a nodeless d_{x^2-y^2}+id_{xy}-wave symmetry of the gap in LSCO. The results of our analysis, in particular the doping dependence of the subdominant d_{xy} gap component, are discussed and compared to the predictions of different theoretical models.Comment: 6 pages, 4 eps figures, presented at SATT11 Conference (Vietri sul Mare, March 2002). To appear in Int. J. Mod. Phy

Antiferromagnetic interactions in single crystalline Zn1-xCoxO thin films

In a rather contradictory situation regarding magnetic data on Co-doped ZnO, we have succeeded in fabricating high-quality single crystalline Zn1-xCoxO (x=0.003-0.07) thin films. This gives us the possibility, for the first time, to examine the it intrinsic magnetic properties of ZnO:Co at a quantitative level and therefore to address several unsolved problems, the major one being the nature of the Co-Co interaction in the ZnO structure.Comment: 4 pages, 4 figures,accepted for publication in PR

Semiclassical treatment of logarithmic perturbation theory

The explicit semiclassical treatment of logarithmic perturbation theory for the nonrelativistic bound states problem is developed. Based upon $\hbar$-expansions and suitable quantization conditions a new procedure for deriving perturbation expansions for the one-dimensional anharmonic oscillator is offered. Avoiding disadvantages of the standard approach, new handy recursion formulae with the same simple form both for ground and exited states have been obtained. As an example, the perturbation expansions for the energy eigenvalues of the harmonic oscillator perturbed by $\lambda x^{6}$ are considered.Comment: 6 pages, LATEX 2.09 using IOP style

Creating a Database of Helicopter Main Rotor Acoustics for Validation of CFD Methods

The work presents recent experiments at the Kazan National Technical University (KNRTU-KAI), related to helicopter acoustics. The objective is to provide a database of near-field experimental data suitable for CFD validation. The obtained set of data corresponds to a Mach-scaled rotor of known planform. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows easy and direct comparisons with CFD predictions, without the need to use far-field aeroacoustic methods

Operational indistinguishably of varying speed of light theories

The varying speed of light theories have been recently proposed to solve the standard model problems and anomalies in the ultra high energy cosmic rays. These theories try to formulate a new relativity with no assumptions about the constancy of the light speed. In this regard, we study two theories and want to show that these theories are not the new theories of relativity, but only re-descriptions of Einstein's special relativity.Comment: 5 pages, 2 figures, title changed, minor changes in notations and formulae, a paragraph added, Int. J. Mod. Phys. D (in press) v

The evidence of quasi-free positronium state in GiPS-AMOC spectra of glycerol

We present the results of processing of Age-Momentum Correlation (AMOC) spectra that were measured for glycerol by the Gamma-induced positron spectroscopy (GiPS) facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states

Fundamental and applied aspects of the chemistry of acetylenylquinones

In addition to the reported synthetic routes for the acetylene derivatives of quinones, a detailed analysis of the fundamental chemical, physicochemical, and biological properties of this class of compounds is presented herein. The advantages of Pd- and Cucatalyzed cross-coupling of terminal alkynes with iodarenes via the Sonogashira reaction to produce new acetylenylquinones with predetermined properties are examined. Here, combining quinoid and acetylene residues into one molecule gives the resulting compounds chemical specificity, as demonstrated by several reported examples of non-trivial transformations. In particular, the presence of the quinoid cycle significantly increases the electrophilicity of the triple bond and determines the range of transformation possibilities. Moreover, acetylenylquinones have heightened sensitivity to both external (such as the reaction temperature and the nature of the solvent) and internal (e.g., the structure of substituents in the nucleus and the acetylene fragment) factors. For example, regioselective cleavage of a strong triple bond under the action of amines is possible in the absence of a metal catalyst. Peri-substituted acetylenyl-9,10-anthraquinones are most suited for the synthetic route because of the proximity of the acetylene and carbonyl groups. Mechanisms of reactions of selective alkynylquinones are described