Effect of Pr-Ca substitution on the transport and magnetic behavior of LaMnO3 perovskite

The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO₃ perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La_1−2x Pr _x Ca _x )MnO₃ (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T _c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.     

Evidence for spin fluctuations in the deep-inelastic reaction 165Ho + 165Ho at 8.5 MeVamu

Both the magnitude and alignment of the transferred angular momentum in the reaction ¹⁶⁵Ho + ¹⁶⁵Ho have been measured as a function of Q-value via continuum γ-ray multiplicity and anisotropy techniques. The spin transfer and the continuum γ-ray anisotropy increase throughout the quasi-elastic region. The spin transfer as a function of Q-value saturates at ~ 35?/fragment, the anisotropy peaks at a value of ~2 and then decreases to near unity for the largest Q-values. The observed anisotropies are in good agreement with predictions from an equilibrium statistical model in which thermal excitation of angular-momentum-bearing collective modes and neutron evaporation give rise to in-plane components of the angular momentum.     

Shrinkage of epoxy cements during hardening

The authors give the results of measurements of the densities of two types of epoxy resin binders during setting from the initial liquid to the final state at room temperature. They assess the role of thermal shrinkage in the overall shrinkage deformation. They show that the coefficient of shrinkage relative to the state of lowest density is greater than the values given in the literature.Moscow Power Institute. Translated from Mekhanika Polimerov, No. 1, pp. 178–181, January–February, 1972.     

Monte Carlo determination of the field dependence of the first Townsend ionization coefficient for atomic hydrogen

The Monte Carlo method has been used to find the /p₀ = f(E/p₀) dependence for atomic hydrogen from E/p₀ = 10 to 100 V/cm-torr· For the calculation it was assumed that elastic collisions and ionization could be accompanied by an atomic excitation corresponding to the transition of a ls electron to a 2s or 2p level.Translated from Izvestiya VUZ. Fizika, No. 8, pp. 70–76, August, 1970.In conclusion the authors thank R. K. Peterkop for moral support of the fundamental idea of this paper.     

Determination of the Molecular Arrangement in Liquid Crystals by Polarization of Fluorescence

Polarized luminescence intensity reading and the polarized absorbance spectra of 4-diethyl-amino-4′-nitrostilbene “impurity” in the n-butyl-p/p-hexyloxyphenyloxycarbonyl/-phenyl-carbonate liquid crystal were measured. Degrees of orientational order, S₁ and S₂, of the nematic liquid were calculated from relative values of the absorbance and luminescence intensity components. A function, which describes the angular molecular distribution with respect to a preferred direction in the liquid crystal, is plotted.