Morphological Stability of the Solid–Liquid Interface during Melt Crystallization of Ca1–xSrxF2 Solid Solution

Crystallography Reports - Proceeding from the phase diagram of the CaF2–SrF2 system, the stability of crystal–melt interface of solid solution against constitutional supercooling has...     

Study of amphiphilic polyester micelles by hyper-rayleigh scattering: invertibility and phase transfer

For the first time, hyper-Rayleigh scattering (HRS) of invertible polymeric micellar structures has been measured. HRS measurements on amphiphilic invertible polyesters with alternating hydrophilic and hydrophobic fragments were carried out in solvents of differing polarity. The observed strong variation of the HRS signals is attributed to the switching behavior of the polyester micelles in the different solvents. The hyperpolarizabilities and the size of the micelles increased with decreasing polarity of the solvent. Observing the dynamics of the solubilization of an insoluble dye (malachite green) by the invertible polyester in toluene confirmed the possibility to reveal conformational changes in polyester macromolecules by HRS. In contrast to UV measurements which showed a continuous increase in absorbance and indicated overall solubilization of the dye, the HRS signals decreased after approaching a maximum value. The decrease of the HRS signals is attributed to the change of dye molecules' orientation within the micelles due to the change of polymeric conformation in toluene. The results have shown that HRS is sensitive to reorientation and ordering of the macromolecules and might become a powerful tool for studying polymer micellar structures as well as phase transfer processes at the nanoscale.     

The near-field effect in a quantum computer

It is shown that in principle it is possible to write optical information on individual quasiresonant atoms in a concentrated system by changing the angle of incidence of an external light wave. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 10, 750–754 (25 May 1999)     

Near-field effect in optics of small objects composed of dipole atoms

A self-consistent problem of interaction of two dipole atoms separated by an unrestricted distance with the field of a quasi-resonance light wave was solved on the assumption that the investigated atoms are Lorentz linear oscillators and the polarizing fields inside the system consist of the Coulomb and the retarded parts. The solution obtained was investigated for the case where the atoms have the same polarizability and the distance between them is much smaller than the length of the external light wave. Formulas for the electric fields inside a small object and outside it have been obtained. It is shown that inside a small two-atom object there can take place longitudinal and transverse optical vibrations accompanied by corresponding dispersion effects depending on the interatomic distance and the angle between the axis of the system and the direction of propagation of the external light wave. The field outside the small object in the wave zone is linearly polarized when the external wave has linear polarization. However, the direction of polarization of the corresponding waves is largely determined by their frequency. It is also shown that the amplitude of the field outside the small object in the wave zone depends greatly on the frequency of the external field and the interatomic distance. The effects observed are considered as a near-field effect in optics of small objects. This phenomena makes it possible to investigate the structure of small objects with the use of optical radiation. Ul'yanovsk Branch of the Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 48 Goncharov Str., Ul'yanovsk, 432700, Russia; e-mail: gadomsky@quant.univ.simbirsk.su. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 765–770, November–December, 1999.     

Oscillatory phenomena at polyvinylpyridine/silica interfaces

Oscillations of the aggregate sizes of SiO₂ particles covered by an adsorbed layer of poly(vinylpyridine) (PVP) at pH 3 with a periodicity of about 15 h were observed using a particle counting technique. The same oscillation was found for the contact angle values of water on the surface of Si wafers (with top silica layer) covered by adsorbed PVP as a function of exposure time in a PVP water solution.     

Estimation of the Upper Limit for the Amplitude of the Dipole Anisotropy of the Total Flux of 25-Gev to 1-Tev Cosmic-Ray Electrons and Positrons

Physics of Atomic Nuclei - Searches for the anisotropy of the total electron and positron fluxes in high-energy galactic cosmic rays are performed. Data collected by the PAMELA magnetic...     

Boron Isotopes in the PAMELA Experiment

Analysis of the isotope composition of nuclei in galactic cosmic rays (GCR) in the PAMELA orbital international experiment allows studying the problems of cosmic-ray origin and propagation in our Galaxy. PAMELA magnetic spectrometer data provided the significant progress in the study of the light nuclei isotope composition of GCR from H to Be in the energy range ∼0.1–1 GeV/nucleon. This makes it possible to estimate the contribution of local (∼100 pc) young (∼10⁶ years) interstellar sources (LISS) into GCR fluxes from supernova explosions. The analysis of boron (B) isotope fluxes in the GCR has so far been carried out only in the energy range ∼0.08–0.17 GeV/nucleon in the space experiments Voyager, Ulysses, ACE. In the present contribution the attempt was done to determine the ¹¹B/¹⁰B ratio in the energy range ∼0.1–1.0 GeV/nucleon for the first time on the base of 2006–2014 PAMELA data using the measurements of the detected nuclei rigidities, velocities and ionization losses in a multilayer calorimeter. The new PAMELA results are consistent with existing as experimental data and those expected from simulations. However the statistical and systematic measurement uncertainties do not allow to separate the local boron source contributions into GCR fluxes. The preliminary results of the boron isotope flux analysis in GCR (¹⁰B, ¹¹B spectra and ¹¹B/¹⁰B ratio dependences on the rigidity and energy) are presented as well as the existing measurement data and simulation results.

     

Laser Fabrication and Fragmentation of Selenium Nanoparticles in Aqueous Media

Physics of Wave Phenomena - The formation of selenium nanoparticles by laser ablation of its target in pure water and water containing biocompatible surfactants has been experimentally...