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High-quality stoichiometric Co2Al-NO3 and Co2Al-CO3 layered double hydroxides (LDHs) have been obtained by precipitation followed by anion exchange, both high-power-sonication assisted. Application of high-power ultrasound has been demonstrated to result in a considerable acceleration of the crystallization process and the anion-exchange reaction. Two independent approaches were used to form bulk and 2-D samples of Co2Al-NO3 with the oriented crystallites, namely uniaxial pressing of deposits from sonicated LDH slurries and magnetic field-assisted arrangement of LDH crystallites precipitating on glass substrates. A convenient way of preparation of semi-transparent compacts with relatively big blocks of oriented crystallites have been demonstrated. Thin dense transparent films of highly-ordered crystallites of Co2Al-NO3 LDH have been produced and characterized. [ABSTRACT FROM AUTHOR]

The antipolar orthorhombic Pnma phase with the √2ap × 4ap × 2 √2ap superstructure (ap ~4 Å is the pseudocubic perovskite unit-cell parameter) is observed in many perovskite compositions derived from BiFeO3. Temperature-induced structural transformations in metastable perovskite solid solutions with the Pnma structure corresponding to the range of 0.30 ≤ y ≤ 0.60 of the (1-y)BiFeO3-y BiScO3 quasi binary system were studied using temperature X-ray and neutron powder diffraction. These compositions cannot be prepared in bulk form at ambient pressure but can be stabilized in the Pnma phase by means of quenching after synthesis under high pressure. The compositions were investigated in situ between 1.5 K and the temperature of the stability limit of their metastable phases (about 870-920 K). It has been found that heating the as-preparedp p compositionsp with the Pnma phase leads to formation of the rhombohedral R3c phase (√2ap × √2ap × 2√3ap), which, on cooling downp toproom temperature, either remains or transforms into a polar orthorhombic Ima2 phase (2ap × √2ap × √2ap). The observed phase transformations in the BiFe1-y Scy O3 perovskite series on heating and on cooling are considered in terms of geometrical factors. [ABSTRACT FROM AUTHOR]

Perovskite ceramics of the Bi1-xLaxFe0.5Sc0.5O3composition (0.30 ≤x≤ 0.35) that cannot be sintered in bulk form as a single phase using the conventional ceramic route were successfully prepared using the high-pressure/high-temperature technique. It has been shown that the room-temperature compositional crossover from the antipolar phase whose incommensurate modulation of displacements of Bi/La and oxygen is described by theImma(00γ)s00 superspace group to the non-polarPnmaphase occurs in the narrow range betweenx= 0.33 andx= 0.34 with no phase coexistence. The features of this compositional crossover are discussed in comparison with that observed in the Bi1-xLaxFeO3system. [ABSTRACT FROM PUBLISHER]

The metastable perovskite phase PbHo 1/2 Nb 1/2 O 3 was first obtained in conditions of high pressures and temperatures. Investigations of structural data and some dielectric properties were carried out. The received data were analyzed in comparison with the other representatives of PbB 1/2 Nb 1/2 O 3 series. [ABSTRACT FROM AUTHOR]

Since endoscopic technique was introduced in transsphenoidal surgery, the midline skull base from olfactory fossa to craniocervical junction has become available through transnasal corridor. One of the most challenging aspects in these types of surgery is watertight closure of skull base defect and prevention of postoperative CSF leaks. Various materials and sealants are applied in different clinics. Recently mucoperiosteal flap from nasal septum was introduced as "gold standard" for multilayer skull base reconstruction. We present our algorithm for selection of skull base reconstruction technique in endoscopic endonasal surgery. We demonstrate our experience of using of pedicled autografts (middle turbinate and mucoperiosteal flap). Surgical technique of grafting is described in details. Clinical results in 41 surgically treated patients are presented. First results of using of pedicled autografts demonstrated high effectiveness of this technique with acceptable rates of nasal complications in comparison to standard methods.