Low threshold gain metal coated laser nanoresonators

We introduce a low refractive index layer between the metal and the gain medium in metal-coated laser resonators and demonstrate that it can significantly reduce the dissipation losses. Analysis of a gain medium waveguide shows that for a given waveguide radius, the low index layer has an optimal thickness for which the lasing threshold gain is minimal. The waveguide analysis is used for the design of a novel three-dimensional cylindrical resonator that is smaller than the vacuum wavelength in all three dimensions and exhibits a low enough threshold gain to lase at room temperature.     

Energy level order in 1,3-dioxane

Conclusions Semiempirical and nonempirical quantum-chemical calculations showed that the highest occupied MO of 1,3-dioxane is an antibonding combination of equatorial oxygen unshared pairs.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1433–1434, June, 1985.     

Macrokinetic model of pyrolysis of carbonaceous feedstock in a tubular reactor

A macrokinetic model of pyrolysis of carbonaceous feedstock in a tubular reactor was proposed. It was shown that, under unsteady-state conditions (at oscillating temperature of feedstock heating), higher conversions can be reached in comparison with steady-state conditions, which agrees with experimental data on flash pyrolysis of biomass in a tubular reactor during heating–cooling cycles.     

Modeling of carbonaceous feedstock pyrolysis in a multichannel reactor

A mathematical model of unsteady-state carbonaceous feedstock pyrolysis in a multichannel tubular reactor was proposed. It was shown that the conversion of feedstock being heated at periodically varying temperature can exceed the conversion on heating at constant temperature. The main design parameters of the multichannel reactor were determined.     

Mononitro-β-carbolines

By the direct nitration of harmane and 1,3-dimethyl-, 1-ethyl-, 1-n-propyl-, and 1-isopropyl--carbolines with concentrated nitric acid or a mixture of nitric and acetic acids, 6- and 8-nitro-1-alkyl--carbolines have been obtained. A chromatographic method for separating the nitration products on alumina is proposed.     

Use of sodium pyrophosphate in the ion-exchange chromatography of oligonucleotides

All-Union Scientific-Research Institute of Molecular Biology. Vektor Scientific-Production Association, Ministry of the Medical Industry, Koltsova, Novosibirsk. Novosibirsk Institute of Bioorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 148–149, January–February, 1992.     

The effect of graphite nanoslabs on thermal oxidative destruction of polyethylene

The impact of graphite nanoslabs on thermal oxidation of polyethylene is studied via the methods of dynamic thermogravimetry and isothermal oxidation. Graphite nanoslabs are shown to exert an inhibiting effect on thermal oxidation of polyethylene, which leads to an increase in the induction period and in the oxygen-absorption rate. That there is an abnormal effect of the nanofiller content on the resistance to thermal oxidative destruction of composites, mainly for diffusion reasons, is established as well.