Anisotropic magnetoresistive and magnetic properties of La_{0.5}Sr_{0.5}CoO_{3-\delta} film

The magnetic and transport properties of La_{0.5}Sr_{0.5}CoO_{3-\delta} film grown on a LaAlO_3 substrate by pulsed-laser deposition are studied. The properties are found to be influenced by the magnetic anisotropy and inhomogeneity. Magnetoresistance anisotropy is determined by the shape anisotropy of the magnetization and the strain-induced magnetic anisotropy due to the film-substrate lattice interaction. Indications of the temperature-driven spin reorientation transition from an out-of plane orderded state at low temperatures to an in-plane ordered state at high temperatures as a result of competition between the mentioned sources of magnetic anisotropy are found.Comment: 5 pages, 8 figures, submitted to Fiz. Nizk. Temp, an extended version of short communication in cond-mat/020734

Experimental Investigation and Numerical Modelling of Dynamic Behaviour of Screw Compressor Plant

An experimental and analytical study of screw compressor operation under unsteady conditions has been carried out. For this purpose a one dimensional model of the processes within a compressor was extended to include other plant components, including tanks and connecting piping. This was based on the differential equations of conservation of mass and energy. The results derived from the model have been verified by experiment in order to obtain a reliable tool that can simulate a variety of scenarios which may occur in everyday compressor plant operation. The analytical model was then further developed to demonstrate whole plant transient operation when a screw compressor is connected with storage tanks, control valves and heat exchangers in a complete system

Cerebral venous disorders: diagnosis, clinical features

Most reports on vascular pathology of the brain have been devoted to arterial blood flow, while morphometric studies of the brain have demonstrated that approximately 85% of the vascular bed of the brain accounts for venous vessels, 10% accounts for the arteries, and about 5% accounts for capillaries. Nevertheless, only a few studies regarding venous pathology of the brain have been published. Many authors admit that the arterial and venous segments of the vascular bed represent a complex interdependent system, where the venous segment is considered to be a highly organized reflexogenic zone responsible for the development of complex, physiologically important, compensatory reactions that provide the constancy of cerebral blood flow. Venous circulation disorders, cerebral venous dyscirculations (CVDs), as well as thromboses of the intracranial veins and sinuses, comprise a significant part of vascular lesions of the brain. The etiologic and pathogenetic aspects of CVD, as well as of thromboses of the intracranial veins and sinuses, have been analyzed. The issues of diagnosis and management of patients with cerebral venous disorders have been considered. Clinical manifestations and characteristics of progression of this pathology have been presented. Cerebral venous thromboses and CVP are often severe, but potentially treatable diseases. Knowledge of the main clinical symptom complexes makes it possible to timely diagnose this pathology and perform effective differentiated pathogenetic and symptomatic therapy in these patients

Thermal boundary resistance of a granular film-substrate interface

The results of measurements of the thermal boundary resistance (RFS) of the interface between a one-layer granular film on a substrate are presented, which reveal the relationship between the RFS value and the grain size in the film material. For a 10-nm-thick nanocrystalline (Fe0.5Co0.5)0.4Cu0.6 film deposited on a silicon substrate with a 50-nm-thick SiO2 oxide layer (interlayer), RFS is increased by almost two orders of magnitude compared to the minimum reported value (10 –7(m2K)/W). The thermal boundary resistance of a La0.65Ca0.35MnO3 film with a microcrystalline structure, which was deposited over a YBa2Cu3O7 –δinterlayer on a SrTiO3 substrate, is RFS = 10–6(m2K)/W

Inelastic Relaxation of Oxygen and Low-Field Magnetoresistance in La0.65\text{}_{0.65}Ca0.35\text{}_{0.35}MnO3\text{}_{3} Films on Ferroelectric Ceramics Substrates

Galvanomagnetic properties of polycrystalline La$\text{}_{0.65}$Ca$\text{}_{0.35}$MnO$\text{}_{3}$ films with a thickness of 0.2~μm deposited onto Pb$\text{}_{2.9}$Ba$\text{}_{0.05}$Sr$\text{}_{0.05}$(Zr$\text{}_{0.4}$Ti$\text{}_{0.6}$)O$\text{}_{3}$ ferroelectric ceramics substrates were investigated. We discovered an irreversible increase in film resistance after numerous inversions of substrate polarization. This phenomenon was investigated several times for three film structures. The typical duration of the process of a monotonic 3-5 times increase in film resistance was 3-6 hours. The long-time relaxation of macroscopic film resistance is explained by dielectrization of film intercrystallite boundaries. The typical size of crystallites of both the film and the substrate is 3-10μm. Such small size explains the fact of macroscopic homogeneity of film conductivity, when the specific resistance increases from 1.8×10$\text{}^{-2}$ to 1.8Ω cm. A growth in resistance of narrow (10 nm) regions of film is explained by the redistribution of oxygen anions under the action of inhomogeneous mechanical stress. The stress between crystallites appears due to inverse piezoelectric effect of ferroelectric substrate. The magnitude of diffusion coefficient of oxygen is estimated to be D≥10$\text{}^{-20}$ m$\text{}^{2}$ s$\text{}^{-1}$