Formation of the complex oxide NaNdTiO<Subscript>4</Subscript>

The processes of phase formation in the Na₂CO₃-TiO₂ and Na₂CO₃-TiO₂-Nd₂O₃ systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO₄ compound occurs through the reaction of the intermediate product Na₈Ti₅O₁₄ with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO₄, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state.     

Laminated anisotropic gently sloping shells and plates subjected to nonsteady forces and various temperature effects

We constructed a new and more accurate model of the state of stress and strain of laminated anisotropic shells and plates that takes into account the influence of dynamic factors on transverse shear strains, thermal strains in the transverse direction, and the non-steady nature of the deformation process. By the variational approach we obtained a system of equations of force-induced motion and the boundary conditions. After representation in the form of the slope deflection method the total order of the system is equal to 20 and does not depend on the number of layers. For rectangular laminated orthotropic pin-supported shells on analytical solution of the nonsteady-state problem of dynamics was obtained by expansion in modes. The results are compared with known three-dimensional solutions, and also with solutions based on other applied theories. The article shows that the introduction of additional desired functions of shear yields a more accurate state of stress and strain of a double-layered plate than the known models.Translated from Problemy Prochnosti, No. 1, pp. 91–101, January, 1996.     

Pheromone specificity inEriocrania semipurpurella (Stephens) andE. sangii (Wood) (Lepidoptera: Eriocraniidae) based on chirality of semiochemicals

The fifth abdominal segment of femaleEriocrania semipurpurella (Stephens) andE. sangii (Wood) contains a pair of exocrine glands. Hexane extracts of this segment were prepared from both species and analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). For both species, the EAD active peaks were identified as nonan-2-one, (Z)-6-nonen-2-one, and (Z)-6-nonen-2-ol by means of mass spectrometry and comparison of retention indices with those of synthetic standards. Enantiomeric separation of chiral alcohols from the female extracts was achieved by gas chromatographic analysis on a cyclodextrin column. InE. semipurpurella, a mixture of (2S,6Z)-nonen-2-ol and (2R,6Z)-nonen-2-ol (2: I) was found, whereas inE. sangii (2S,6Z)-nonen-2-ol was the predominant enantiomer and only traces of theR enantiomer were indicated by the antennal response. In field tests, a blend of the three compounds was not attractive to conspecific males. A subtractive assay showed that the alcohol in various enantiomeric mixtures was the only attractive compound, whereas addition of (Z)-6-nonen-2-one to the alcohol completely inhibited the attraction of both species. A trapping experiment including a wide range of ratios between theR andS enantiomers showed that baits containing 95–100% of theS enantiomer were attractive to maleE. sangii, whereas males ofE. semipurpurella were attracted to all tested ratios of the enantiomers. However, the response profiles of maleE. semipurpurella differed between populations from southern Sweden, south Finland, and the Kola Peninsula in Russia. In south Sweden males were maximally attracted to a racemic mixture of the alcohols. At the Kola PeninsulaE. semipurpurella was attracted to baits containing 95–100% of theR enantiomer. In south Finland all tested ratios between 0 and 100%R enantiomer trappedE. semipurpurella, but the trap catches appeared to be bimodally distributed with peaks around 15 and 70%R enantiomer. The trapping results suggest the existence of pheromone races or sibling species among the specimens identified asE. semipurpurella.Dedicated to Prof. H. J. Bestmann on the occasion of his 70th birthday.     

Nuclear superheating of steam,results and prospects at the present stage

Conclusions The operating experience of the BAEPP reactors has confirmed the possibility of the industrial realization of nuclear superheating of steam right up to 510–540°C, sufficient reliability, and the safety of reactors of this class.The introduction of nuclear superheating is economically justified: when steam is superheated to 500°C and higher with the use of stainless steels as the construction material in the active zone and the use of removable and sleeve fuel elements; when zirconium alloys are used in the active zone and the steam temperature is450°C, and when rod fuel elements, nonremovable channels, and the appropriate organization of steam in the channel is used.Reactors with nuclear superheating of steam permit operation under variable conditions and at atomic heat and electric power plants with channeling of the heat to domestic and industrial needs.Channel-type reactors with nuclear superheating permit enlarging capacity on the basis of standard units and the use of high-speed turbine units having large capacity, and they significantly reduce the thermal emissions into the environment.Translated from Atomnaya Énergiya, Vol. 44, No. 2, pp. 126–131, February, 1978.     

Phase diagram of the LaFeO3-LaSrFeO4 system

The phase relationships in the LaFeO₃-LaSrFeO₄ system at temperatures in the range 1000–2100°C in air are investigated, and the phase diagram of the system is constructed. One perovskite-like compound, namely, La₂SrFe₂O₇, which belongs to the Ruddlesden-Popper phases, is revealed in the system.     

Study on thermolysis process of a new hydrated and protonated perovskite-like oxides H2K0.5Bi2.5Ti4O13·yH2O

A protonated form of the n?=?4 layered bismuth containing perovskite-like titanate K_2.5Bi_2.5Ti₄O₁₃ belonging to Ruddlesden-Popper phases was prepared via ion exchange reaction of interlayer K⁺ with protons. Its composition was investigated by TG ICP and EDX analysis was found to be H₂K_0.5Bi_2.5Ti₄O₁₃·H₂O. The thermal behavior of the obtained phase was investigated by STA coupled with mass-spectrometry, the structural changes, happening with the sample during heating, were examined by XRD. It was shown that the as-prepared hydrated phase undergoes two-stage dehydration at low temperatures (up to 160?°C). The further heating leads to the gradual decomposition and crystallization of new phases, notably Bi₂Ti₂O₇, Bi₄Ti₃O₁₂ and Bi₂Ti₄O₁₁. The morphology of the as-prepared sample and samples after heat treatment was examined using SEM.     

Thermally Stimulated Evolution of the Surface of Ni- and Cu-Containing Plasma-Electrolytic Oxide Coatings on Titanium

Protection of Metals and Physical Chemistry of Surfaces - The effect of the temperature of annealing in air on the surface architecture and composition of oxide layers has been studied....     

On stabilization of the Fermi level in Ga-doped PbTe-based alloys

The influence of Ga doping and irradiation with high-energy electrons on the galvanomagnetic effects in n-Pb_1?xGe_xTe:Ga (0.04?x?0.06) was investigated. Transitions to the metal-type conduction were found to occur both with an increase in the impurity content and as a result of irradiation. It is concluded that the impurity level does not pin the Fermi level. It is demonstrated that gallium doping and electron irradiation are the most effective complementary methods for controlling the electrical properties of alloys.     

Observation of ferrobielastic twinning in GaPO4 underuniaxial stress

The phenomenon of ferrobielastic twinning stimulated by uniaxial pressure is optically observed in quartz-like material GaPO₄. For X-cut samples interdomain boundaries were detected at the pressure level 350 MPa applied at the angle 45° with respect to Z axis. In similar experiments with AlPO₄ domain boundaries were not observed     

The capacity to distinguish short durations of time intervals in children and adults]

Two groups of children (5-6-year-old and 7-8-year-old) were presented with pairs of sound signals of the same or different durations. Sound signal durations in pairs could be 1.0, 1.2, 1.5, and 2.0 sec. The children had to detect the difference between the sounds in a pair. The obtained data were compared to the analogous results shown by the 18-39-year-old subjects. It was found out that the ability to discriminate intervals of short duration substantially improved with age. This phenomenon in presumably connected with perfection of the short-term memory. Independently of the subject's age, the order of presentation of signals in a pair influences the ability to discriminate between their durations.