Transition to gapless superconductivity in YBa2(Cu1−x Zn x )3O7

Point-contact spectra of YBa₂(Cu_1–x Zn _x )₃O₇/Ag are studied at various temperatures. The differential resistance dV/dI of the point contacts shows gap-related structures belowT _c which can be attributed to Andreev reflection. Evaluation of many spectra for each sample taken at 4.2 K yields a wide distribution of voltages /e at which these structures occur. The upper limit varies roughly as expected from the depression ofT _c by Zn-doping from /e=29 mV (x=0) to 9 mV (x=0.05), while the lower limit decreases much faster and disappears forx=0.05. Hence, the Zn doped samples exhibit a tendency to gapless superconductivity as suggested earlier on the basis of specific-heat measurements.     

Point-contact spectroscopy of the electron-phonon interaction in LaNi5

The electron-phonon interaction in LaNi₅ is studied by point-contact spectroscopy. The spectrum corresponding to the electron-phonon interaction function g (the phonon density of states modulated by the matrix element of the electron-phonon interaction) is found. The functiong is used to analyze the point-contact spectra of PrNi₅, where besides the electron-phonon contribution there is also an interaction between the conduction electrons and the crystal electric field levels of the Pr³⁺ ion.     

Physiological significance of changes in bone volume associated with deformation

The changes of volume and the compressibility characteristics of the compact bone tissue of the human tibia in longitudinal tension have been investigated in six different zones of the cross section. It has been established that when a man is walking the relative volume deformation of the bone is comparable with the volume of blood flowing through the tibia during the load-bearing period. It is suggested that the forced cyclic deformations of the bone tissue may significantly modify the level and character of the blood flow through the bone.     

Determination of the elastic characteristics of compact bone tissue by investigation of the natural vibration frequency

The dynamic elastic H and shear G_dyn moduli of compact bone tissue have been determined by investigating the natural vibration frequency of specimens obtained from long tubular human bones. The modulus of elasticity E has also been determined by conducting mechanical bending tests. The value of the H modulus is found to change in the course of storage.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 167–172, January–February, 1971.     

Cathodic corrosion as a facile and effective method to prepare clean metal alloy nanoparticles

The cathodic corrosion method described here is a simple, clean, and fast way of synthesizing nanoalloys with high catalytic performance. Using a series of Pt-Rh alloys as an example, we show that this one-step method can convert a bulk alloy electrode into an aqueous suspension of nanoparticles, retaining the composition and crystal lattice structure of the starting alloy. Compared to pure metals, these alloy nanocatalysts are more active toward CO and methanol oxidation and nitrate reduction reactions. Nanoparticles made of PtRu, PtIr, PtNi, AuCo, AuCu, and FeCo bulk alloys demonstrate the universality of this synthesis method.