Properties of low-refractive-index films obtained by the close-spaced vapor transport technique under the sublimation of graphite in a quasi-closed volume

The properties of low-refractive-index carbon films obtained by close-spaced vapor transport at graphite sublimation are studied. The optical properties of the films are investigated by monochromatic multiple-angle ellipsometry, and their morphology is examined by AFM. It is found that the films have a columnar structure with a background surface roughness of about 1 nm. In addition, the surface of the film contains islands up to 50 nm in height with a footprint of ≈200 nm. A low-refractive-index carbon film deposited by close-spaced vapor transport on silicon tips is found to decrease the field emission threshold and drastically raise the current.     

Effects of interaction of nanoparticles in a highly anisotropic ferrimagnet

This paper reports on a study of the field and temperature dependences of the parameters of the particle magnetic interaction in a densely packed system of nanocrystals of the highly anisotropic hexagonal ferrite BaFe₁₂O₁₉ with the particles distributed in diameter within the range 10—100 nm and having volumes satisfying the criterion of “small Stoner—Wohlfarth particles.” It is shown that the resultant particle interaction in the temperature range 300 K≤T≤640 K has a negative sign, whereas for T>640 K, it is positive. The maximum values of the parameter Δm allow classification of the interaction as moderate in strength. The temperature dependences of the interaction parameters are found to correlate with manifestation of the size and surface effects in the system, which are characteristic of small particles (transition to the superparamagnetic state, “surface” anisotropy, and reduced exchange interaction in a structurally defective near-surface layer of particles).     

Morphology and spectral properties of thin films of benzoxazole derivatives of biphenyl

We have studied the spectral properties and morphology of thin films (TVD films) formed by thermal vacuum deposition of 4,4′-bis[(E)-1-(1,3-benzoxazol-2-yl)-2-ethenyl]-1,1′-biphenyl and its substituted derivatives. We have shown that introducing bulky 2,2′-oxyhexyl substituents into the biphenyl units leads to a shift of the fluorescence maximum for the TVD films toward shorter wavelengths, a decrease in their photostability, and aggregation of the films during storage. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 300–303, May–June, 2007.     

Synthesis and fungicidal activity of the quaternary ammonium salts of the 1,3,7-substituted dibenzothiophene-5,5-diones

A series of novel double quaternary ammonium salts based on 5,5-dioxo-5H-dibenzo[b,d]thiophene has been prepared via quaternization of the corresponding 3,7-bis(chloromethyl)dibenzothiophene-5,5-diones with various N,N-dimethylalkylamines. Pronounced fungicidal activity of the C¹-substituted quaternary ammonium salts has been observed.     

Dynamics of Impulse-Loaded Beam with One-Sided Support Ties

International Applied Mechanics - The pulsed deformation of a beam with hinged ends and discretely elastically supported span is considered. It is assumed that due to separation of the beam from...     

Mesomorphism of thermotropic poly(propyleneimine) dendrimers and phase equilibria in systems on their basis

The thermotropic mesomorphism of poly(propyleneimine) dendrimers of first, second, and third generations has been studied by the methods of polarization thermomicroscopy and DSC. Phase diagrams for the binary systems of dendrimers with n-amyloxy-n′-cyanobiphenyl calamite liquid crystal and hexa(pentyloxy)triphenylene discotic liquid crystal have been constructed. Measurements have been carried out over the entire concentration range at temperatures corresponding to the stable states of nematic, columnar, and isotropic phases. The effects of the chemical nature and shape of linear and cyclic mesogen molecules on the manifestation of mesomorphism in LC dendrimers are considered.     

Utilization of Slovak bentonites in deposition of high-level radioactive waste and spent nuclear fuel

The basic strategic aims in the field of managing high-level radioactive waste and liquidation of nuclear power plants are all contained in the Energy policy of the Slovak Republic. Its aim is to resolve the concept of the backside of the nuclear energetics fuel cycle??long-term deposition of high-level radioactive waste and spent nuclear fuel (SNF). The most important form of high-level radioactive waste and SNF long-term deposition is their deposition in deep geological formations created by natural as well as engineering barriers used to isolate the long-lived radionuclides from the biosphere. The basic components of these barriers are clays, of which bentonite is generally referred to as the most suitable clay material. There are a few significant bentonite deposits in the Slovak Republic: Jel?ový potok, Kopernica, Lastovce, Lieskovec, Dolná Ves. The review article summarizes the information on geotechnical properties of Slovak bentonites published up-to-date, which is inevitable to know for the intention of their use. It highlights the advantages and shows drawbacks of five Slovak deposits. It suggests further research direction, to draw a thorough hydraulical, microbial and radiation profile of Slovak bentonites.     

Causes of the double maximum conductivity of nanocomposite polymer electrolytes for lithium power sources

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