Influence of equal-channel multi-angle pressing on mechanical and transport properties of a multi-fibrous NbTi superconductor

The effect of equal-channel multi-angle pressing combined with hydroextrusion and drawing followed by thermal treatment on critical current density, superconducting transition temperature and mechanical properties of a multi-fibre (210 fibres) superconducting wire made of a Nb + 50 wt% Ti alloy has been investigated.     

Crystal and molecular structure and vibrational spectra of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol and its complex with cerium(III) nitrate

The structure of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol 2,6-[Ph₂P(O)CH₂]₂-4-MeC₆H₂OH(L¹) and its 1: 1 complex with cerium(III) nitrate were studied by X-ray diffraction. A rather strong intramolecular hydrogen bond P=O…H-O (O…O, 2.646(1) Å) exists in the L¹ molecules. In the crystal, the molecules are combined into centrosymmetric dimers through the stacking interaction between the central phenol rings; the distance between the ring planes is 3.39 Å. In the complex molecule, [Ce(L¹)(NO₃)₃ · Me₂C(O)], the neutral ligand L¹ is tridentate and the three nitrate ions are bidentate, and the tenth coordination site is occupied by acetone oxygen. No intramolecular H-bonds are present. In the crystal, the complex molecules are combined into centrosymmetric dimers through intermolecular hydrogen bonds O-H…O-NO₂ (O…O, 2.713(8) Å). The vibrational (IR, Raman) spectra of the ligand and the complex were studied and the principal bands were assigned. According to IR spectroscopy, the P=O…H-O intramolecular hydrogen bond is retained in both the ligand and the complex molecules.     

Behavior of metallic shaped-charge jets with passage of a pulsed electric current through them

The paper reports results of experimental and numerical studies of the disruption of metallic shaped-charge jets by passage of a pulsed electric current through them. Experimental results are presented in the form of x-ray photographs of shaped-charge jets with and without a current and tables of penetration depths in targets. Numerical simulation of the disruption of shaped-charge jets with a current is performed for three possible mechanisms of disruption (development ofMHD instability of shaped-charge jets, volume fracture, and simultaneous development ofMHD instability and volume fracture). Numerical and experimental results are compared. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 3, pp. 19–25, May–June, 2000.     

The solvability of the equations of motion of mechanical systems with sliding friction

The problem of the existence of local classical solutions of the equations of motion of holonomic systems with sliding friction is investigated. The conditions for the equations of motion to be solvable for the accelerations enable estimates to be obtained of the coefficients of friction, within the framework of which (from the point of view of the existence of solutions) Coulomb's laws can be used to describe the dynamics of mechanical systems with sliding friction.     

Pull-in and pull-out effects in synchronization of chaotically modulated oscillations

We study the synchronization effects of chaotically modulated oscillations of two unidirectional coupled chaos generators based on a typical phase-locked system. This work was presented at the Summer Workshop “Dynamic Days” (Nizhny Novgorod, June 30–July 2, 1998). Lobachevsky State University of Nizhny Novgorod, Institute of Applied Mathematics and Cybernetics, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 12, pp. 1525–1530, December, 1998.     

Femtosecond pulse generation with a diode-pumped Yb3+:YVO4 laser

A diode-pumped Yb:YVO4 laser has been passively mode locked for the first time, to our knowledge. 120 fs pulses with an average output power of 300 mW and a peak power as high as 14.5 kW are obtained by use of a semiconductor saturable-absorber mirror for passive mode locking. The optical spectrum has a 10 nm bandwidth (full width at half-maximum) and is centered at 1021 nm.     

Acid-base properties of phosphoryl compounds 14. Hydrogen-bond polarity in complex phosphoryl compounds

Conclusions Dipole moments have been measured for phosphoryl compound complexes with alcohols and substituted phenols. A scheme for calculating the H-bond polarity (_h) in these systems is discussed; the value of _H can be described in terms of a charge transfer model.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2288–2292, October, 1978.The authors wish to thank B. A. Kvasov for his help with the measurements on the NMR spectra.