Investigation of mass attenuation coefficients of water, concrete and bakelite at different energies using the FLUKA Monte Carlo code

The mass attenuation coefficients of water, bakelite and concrete sample defined in the simulation package were obtained using the FLUKA Monte Carlo code at 59.5, 80.9, 140.5, 356.5, 661.6, 1173.2 and 1332.5 keV photon energies. The results for the mass attenuation coefficients obtained by simulation have been compared with experimental and the theoretical ones and good agreement has been observed. The results indicate that this process can be followed to determine the data on the attenuation of gamma-rays with the several energies in other materials. Also, the deposited energy by 661.6 keV photons at several thicknesses of each media was determined as being an important data for radiation shielding studies.     

Silver Nanoparticle Thin Films with Nanocavities for Surface‐Enhanced Raman Scattering

The formation of nanometer‐sized gaps between silver nanoparticles is critically important for optimal enhancement in surface‐enhanced Raman scattering (SERS). A simple approach is developed to generate nanometer‐sized cavities in a silver nanoparticle thin film for use as a SERS substrate with extremely high enhancement. In this method, a submicroliter volume of concentrated silver colloidal suspension stabilized with cetyltrimethylammonium bromide (CTAB) is spotted on hydrophobic glass surfaces prepared by the exposure of the glass to dichloromethysilane vapors. The use of a hydrophobic surface helps the formation of a more uniform silver nanoparticle thin film, and CTAB acts as a molecular spacer to keep the silver nanoparticles at a distance. A series of CTAB concentrations is investigated to optimize the interparticle distance and aggregation status. The silver nanoparticle thin films prepared on regular and hydrophobic surfaces are compared. Rhodamine 6G is used as a probe to characterize the thin films as SERS substrates. SERS enhancement without the contribution of the resonance of the thin film prepared on the hydrophobic surface is calculated as 2×10⁷ for rhodamine 6G, which is about one order of magnitude greater than that of the silver nanoparticle aggregates prepared with CTAB on regular glass surfaces and two orders of magnitude greater than that of the silver nanoparticle aggregates prepared without CTAB on regular glass surfaces. A hydrophobic surface and the presence of CTAB have an increased effect on the charge‐transfer component of the SERS enhancement mechanism. The limit of detection for rhodamine 6G is estimated as 1.0×10^?8 M . Scanning electron microscopy and atomic force microscopy are used for the characterization of the prepared substrate.     

Structure of the mixed state induced in thin YBaCuO superconducting films by the field of a small ferromagnetic particle

The temperature dependence of the local energy barrier to formation of the mixed state in YBaCuO thin-film superconducting samples has been determined. The measurement technique is based on use of a small ferromagnetic particle as the magnetic field source. It is found that the energy barrier to creation of vortices (for the field oriented parallel to the CuO planes) is anomalously small while the dependence of the corresponding threshold current j _c(T) differs substantially from the temperature dependence of the pair-breaking current. The experimental results are interpreted in terms of the model of a Josephson medium. The observed temperature dependence of j _c points to a strong suppression of the superconducting order parameter at the intergrain boundaries, which for the most probable type of boundaries: superconductor-insulator-superconductor, is evidence of anisotropic pairing. Zh. éksp. Teor. Fiz. 116, 1735–1749 (November 1999)     

On The “Nonresonance” Parametric Cyclotron Radiation

We study the effect of amplification of coherent bichromatic radiation due to its cyclotron parametric interaction with a modulated ensemble of classical electron oscillators. The mechanism of energy exchange between the radiation and the electrons in the absence of partial synchronism of the waves and particles is analyzed. The features of the energy exchange in the course of interaction of the waves with relativistic and nonrelativistic particles are pointed out.     

Readjustment of ferroelectric domain structure under the action of polarized light

Change in the 180 domain structure of a gyrotropic ferroelectric produced by circularly polarized light is considered. Due to circular dichroism the photoinduced polarization differs in adjacent domains with different spontaneous polarization directions, as a result of which the domain dimensions change, the period of the structure is decreased, and the crystal as a whole becomes photopolarized.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 17–20, June, 1984.     

Applicability of alkanet (Alkanna tinctoria) extract for the histological staining of liver tissue

Staining of tissue is a significant process in histotechnology and staining techniques are used in the examination and diagnosis of diseases. The increase of international awareness for the environment, ecology, and health directed people to reduce toxic effluents and stop usage of dangerous chemical dyes. The present trend throughout the world is shifting towards to use of natural products over their synthetic alternatives. Therefore, in this study, the dyeing ability of alkanet plant on the cells of unstained sections taken from Wistar rat liver was investigated. The extract of Alkanna tinctoria contain naphthaquinone group of dyestuff. Chemical characterization of A. tinctoria extract was performed with HPLC-TOF/MS and UV spectra analysis, respectively. Different metal salts were used in the staining processes in order to obtain different colors. In the staining of without adding mordant (metal salt) to the extract, pale brown staining was obtained in the cytoplasm. Light pink color was obtained with the addition of CuSO₄ mordant. Dark pink-red color was achieved by adding alum, and also NiSO₄ was added for light purple staining. The staining of cytoplasm of different cells in liver tissue was achieved successfully with the extract of A. tinctoria and different colors were obtained using various mordants.     

Photomagnetization of polydomain magnetic insulators by circularly polarized light

A new effect of magnetization of magnetic insulators due to light absorption by magnetic ions is proposed. The estimates for an yttrium ion garnet crystal are made.     

Investigation of Luminescence Properties of Eu3+, Dy3+ and Gd3+ Doped MgAl2Si2O8 Red‐emitting Phosphors

Rare‐earth‐doped aluminosilicates of alkaline earth MgAl₂Si₂O₈: Eu³⁺, Dy³⁺ and MgAl₂Si₂O₈: Eu³⁺, Gd³⁺ were synthesized by the solid state reaction method at 1300 ^oC. The phosphors were characterized by X‐ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). X‐ray powder diffraction studies show that the phosphors were crystallized in the triclinic crystal system. The phosphors show characteristic broad band phosphorescence of Eu³⁺. This broad band phosphorescence has red emission bands in the range of 580–705 nm corresponding to ⁵D₀ → ⁷F_j (j:0,2,3,4) transitions of Eu³⁺.     

Synthesis,Characterization and Oxide Ionic Conductivity of Binary β‐(Bi2O3)1‐x(Lu2O3)x System

In this research, the effects of doping Lu₂O₃ to α‐Bi₂O₃ in the range of 0.01 < x < 0.10 in a series of different mole fractions (1% < n < 10% mole ratios) was studied. Beside, heat treatment was performed by applying a cascade temperature rise in the range of 700‐800 °C for 72 hours and new phases were obtained in the (Bi₂O₃)_1‐x(Lu₂O₃)_x system. After heat treatment for 72 hours at 800 °C; mixtures, containing 2‐8% mole Lu₂O₃, formed a tetragonal phase. As a result of subjecting mixtures, containing 9% and 10% mole Lu₂O₃, to a quenching process at 825 °C, tetragonal phases were obtained. With the help of XRD, the crystal systems and lattice parameters of the solid solutions were obtained and their characterization was carried out. Thermal measurements were made by using a simultaneous DTA/TG system. The total conductivity (σ_T) in the β‐Bi₂O₃ doped with Lu₂O₃ was measured using the four‐probe DC method.