Quantitative determination of magnetic fields from iron particles of oblong form encapsulated by carbon nanotubes using electron holography

Using electron holography (interference electron microscopy) we have made measurements of the magnetic flux and magnetic field distribution around a carbon nanotube filled with iron. At the surface of the carbon nanotube, an iron particle with a radius of 30 nm and a length of 200 nm created a magnetic flux of 10⁻¹⁵ Wb (Weber) and a magnetic field of 0.3–0.4 T (Tesla). The theory developed in this work is constrained to the case of cylindrical symmetry of the investigated ferromagnetic particles, but, in general, such studies can be made for ferromagnetic particles of any shape.     

Kinetic studies on the thermal dissociation of the inclusion complex of β-cyclodextrin with cinnamic aldehyde

The stability of the inclusion complex of jp25j4pgl815w1tl/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD with cinnamic aldehyde was investigated by means of TG and DSC. The mass loss takes place in three stages: dehydration occurs at 50–120°C; dissociation of jp25j4pgl815w1tl/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD·C₉H₈O proceeds in the range 200–260°C; and decomposition of jp25j4pgl815w1tl/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD begins at 280°C. The kinetics of the dissociation of jp25j4pgl815w1tl/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD·C₉H₈O was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results demonstrate that the dissociation of jp25j4pgl815w1tl/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD·C₉H₈O is dominated by a one-dimensional diffusion process. The activation energyE is 160 kJ mol^–1, and the pre-exponential factorA is 5.8×10¹⁴ min^–1. Scanning electron microscope observations and the results of crystal structure analysis are in good agreement with those of thermogravimetry.     

β-Substituted cyclopropyl rádicals grafted to silica surface. Methods of preparation,structure, and properties

Cyclopropyl type radicals jp1n38/11172_2004_Article_BF00713599_TeX2GIFIE1.gif" alt=" $$X - _\triangledown \cdot (X = \begin{array}{*{20}c} \backslash \\ --- \\ / \\ \end{array} C, \begin{array}{*{20}c} \backslash \\ --- \\ / \\ \end{array} Si, \begin{array}{*{20}c} \backslash \\ --- \\ / \\ \end{array} Si---O)$$ " align="middle" border="0"> were identified on a surface of activated silica by ESR. The possibility of their preparation by two methods,i.e., by photocyclization of substituted allyl radicals and by interaction of cyclopropane molecules with particular surface defects, was demonstrated. The effects of jp1n38/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-substituents on radiospectroscopic characteristics and thermal stabilities of the radicals were studied. Rate constants and activation energies of decomposition of substituted cyclopropyl radicals were estimated. The experimental data obtained were compared with the results of quantum-chemical calculations of model systems. The mechanism of photocyclization of allyl radicals was discussed. The transition states of decomposition of cyclopropyl and jp1n38/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-fluorine-substituted cyclopropyl radicals were calculated. Electronegative substitution was found to result in a considerable decrease in the activation energy of the cyclopropane ring opening.The authors are grateful to E. G. Baskir for calling their attention to this publication.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2409–2421, December, 1995.The work was carried out with financial support of the Russian Foundation for Basic Research (Project code 94-03-09137) and the International Science Foundation (Grant No. MK9000).     

Minimal non-$${\mathcal {F}}$$ -groups

Let jp28q64019810512/11587_2009_44_Article_IEq2.gif" alt="$${\mathcal {F}}$$" align="middle" border="0"> be a saturated formation. We describe minimal non-jp28q64019810512/11587_2009_44_Article_IEq3.gif" alt="$${\mathcal {F}}$$" align="middle" border="0"> -, minimal non-jp28q64019810512/11587_2009_44_Article_IEq4.gif" alt="$${\mathcal{AF}}$$" align="middle" border="0"> -, and minimal non-metabelian groups. Dedicated to L. A. Shemetkov on the occasion of his seventieth birthday.