Ultrasharp h-BN Nanocones and the Origin of Their High Mechanical Stiffness and Large Dipole Moment.

We report on experimental synthesis and theoretical studies of ultrasharp BN-nanocones. Using scanning and transmission electron microscopy, the cone-like morphology of synthesized products was confirmed. Theoretical analysis of the dipole moment nature in h-BN nanocones reveals that the moment has contributions from the polarity of B-N bonds and electronic flexoelectric effect associated with a curved h-BN lattice. The latter phenomenon is predicted on the basis of the extension of the theory of flexoelectric effects in the h-BN lattice through establishing universality of the linear dependence of flexoelectric dipole moments on local curvature in various nano- h-BN networks (nanotubes and fullerenes). Our study of the atomic structure response and its polarization under deformation of nanocones with different apex angles shows the advantageous properties of cones with the smallest angles.

Dramatic role of critical current anisotropy on flux avalanches in MgB2 films.

Anisotropic penetration of magnetic flux in MgB(2) films grown on vicinal sapphire substrates is investigated using magneto-optical imaging. Regular penetration above 10 K proceeds more easily along the substrate surface steps, the anisotropy of the critical current being 6%. At lower temperatures the penetration occurs via abrupt dendritic avalanches that preferentially propagate perpendicular to the surface steps. This inverse anisotropy in the penetration pattern becomes dramatic very close to 10 K where all flux avalanches propagate in the strongest pinning direction. The observed behavior is fully explained using a thermomagnetic model of the dendritic instability.

[Discogenic lumbosacral radiculitis]. / Diskogennyi poiasnichno-kresttsovyi radikulit.

A total of 74 patients with suspected discal hernia were studied. To clarify its diagnosis, epidural scintigraphy along with routine studies was used. The established diagnosis was verified during surgery. Carbonic acid laser was applied to 22 patients in addition to the conventional procedures.

[Methods of regional analgesia in closed trauma of the chest]. / Metody regionarnoi anal'gezii pri zakrytoi travme grudi.

The literature data has been analysed to evaluate the efficacy of the methods of regional analgesia (RA) in closed chest trauma. Various types of blocks are described. Epidural analgesia with local anaesthetics and narcotics is detailed. Epidural electrostimulation and introduction of drugs affecting the endogenous systems are shown to show good promises.

[Epidural analgesia in the treatment of the pain syndrome in degenerative dystrophic disorders of the lumbar spine]. / Epidural'naia analgeziia v lechenii bolevogo sindroma pri degenetativno-distroficheskom porazhenii poiasnichnogo otdela pozvonochnika.

Epidural analgesia (EA) with dicaine and morphine has been compared in 34 patients with pain syndrome caused by degenerative dystrophy of lumbar vertebrae. The advantages of EA with dicaine have been observed. 35.3% of patients have been subject to surgery. In the rest of patients pain syndrome was relieved. Radionuclide epidurography has shown that the volume of the anesthetic solution injected should not exceed 10 ml.

[A rare complication of regional anesthesia]. / Redkoe oslozhnenie regionarnoi anestezii.

A prolonged blockade of the brachial plexus by a subclavicular approach was performed in a 22-year-old patient with combined trauma and severe pain in the left arm. The administration of 20 ml of a 0.3% dicaine solution through a catheter led to spinal anesthesia accompanied by the development of transient hemodynamic and respiration disturbances, which were arrested without medication or controlled lung ventilation. A possible reason for this complication is traumatic plexitis. When performing a blockade of the brachial plexus one should administer a test dose of an anesthetic prior to the entire drug dosage.