Effect of microcrystallinity on the mechanical performance of polycarbonate

Samples of polycarbonate (PC) before and after remelting and isothermal solidification treatment were characterized by wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS), microhardness, and stretching calorimetry techniques. Both PC samples could be regarded as structurally identical (X-ray amorphous); however, the isothermally solidified sample exhibited higher microhardness and Young's modulus, as well as a lower linear expansion coefficient and greatly reduced breaking strain. These results are attributed to the overlap of a network of ultramicrocrystals on the original entanglement network in the reference (untreated) PC sample.     

Magnetoreflection and magnetotransmission of light in manganites with CMR

The influence of a magnetic field on the reflection and transmission spectra of natural light is studied in the visible and infrared ranges of the spectrum in films and single crystals of manganite La_0.7Ca_0.3MnO₃ with colossal magnetoresistance. The magnetoreflection and magnetotransmission effects are analyzed using the magnetorefractive approach developed for manganites.     

Urease‐Catalyzed Carbonate Precipitation inside the Restricted Volume of Polyelectrolyte Capsules

A new biomimetic approach for performing CaCO₃ synthesis exclusively inside micron‐sized polyelectrolyte capsules, based on the fermentative formation of a precipitative agent (CO₃²⁻ anion) by urease‐catalyzed urea hydrolysis, was developed. Precipitated CaCO₃ completely fills the interior capsule volume and has a metastable vaterite phase.

     

Emission Spectra of Cascade Decay Processes Initiated by K-Ionization of Argon

The M ₁ -M ₂₃ and L ₂₃ -M ₁ emission spectra of the cascade decay of the Ar K-ionization states are calculated. The spectra have a complex satellite structure reflecting the dynamics of the decay process. In the case of the L ₂₃ spectrum, the anomalous increase in the fluorescence yield in the highly ionized intermediate configurations of the cascade leads to significant changes in the absolute values of transition probabilities and in the relative intensities of spectral lines.     

Direct observation of phase separation in La1−x CaxMnO3

In a study of the infrared optical absorption spectra of polycrystalline La_1−x Ca_xMnO₃ (0.1⩽x⩽0.8), a contribution from free charge carriers is observed below the Curie temperature for compositions with x⩽0.4. The existence of this contribution for samples with a high resistivity is a direct proof of the existence of “metallic” drops in an insulating matrix. The relative volume of the “metallic” phase is estimated. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 89–92 (10 July 1998)     

Tunneling of optical beams through inhomogeneity of a refractive index

We consider the effect of tunneling of optical beams through a narrow induced inhomogeneity in a refractive index. It is shown that under the condition of total internal reflection from the induced channel, part of the signal beam leaks if the channel is narrow. Dependence of the pump beam width at which the tunneling of half signal power occurs is found as a function of the pump intensity and the angle of beam crossing.