Methods for Producing High-Temperature Superconductors

This paper presents technologies for obtaining high-temperature superconducting materials

Electronic properties and phase transitions in low-dimensional semiconductors

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, non-linear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. Electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.Comment: 70 pages, 38 figure

Clinical and hemodynamic effects of carvedilol in patients with hypertrophic cardiomyopathy

Aim. To study carvedilol effectiveness in patients with hypertrophic cardiomyopathy (HCMP). Material and methods. The study included 52 patients with HCMP (67% men and 33% women; mean age 40,7±3,1 yeas). All participants underwent clinical examination, six-minute walk test (6mwt), standard 12-lead electrocardiography (ECG), echocardiography (EchoCG), chest X-ray with cardio-thoracic index calculation, and angina severity assessment using a verbal assessment scale (VAS). All patients were divided into two groups: Group I (n=38) with interventricular wall thickness (IVWT) ≤20 mm; and Group II (n=14) with IVWT >20 mm. Carvedilol was titrated from the minimal dose of 6,25 mg/d to the maximal dose of 31,25 mg/d (b. i.d.). The treatment duration was 12 weeks. Results. Carvedilol therapy was associated with an improvement of clinical and hemodynamic parameters (including reduced angina severity and improved left ventricular diastolic function, LVDF) in both groups. The effectiveness of conservative treatment was higher in patients with IVWT <20 mm. Conclusion. In HCMP patients, the severity of clinical symptoms and non-specific ECG disturbances increased in parallel with the IVW hypertrophy progression. Carvedilol therapy demonstrated beneficial effects on clinical status, cardiac hemodynamics, and LVDF. These effects were maximal in patients with IVWT <20 mm

Heart remodelling type role and effectiveness of lisinopril and bisoprolol therapy among patients with rheumatic mitral disease

Aim. To study the association between heart remodelling types and cardiac arrhythmias; to assess the effectiveness of lisinopril and bisoprolol therapy in patients with rheumatic mitral disease (RMD).Material and methods. In total, 48 patients (mean age 49,5±3,8 years) with RMD were divided into two groups: Group I (n=28) with predominant mitral stenosis (MS) and Group II (n=20) with predominant mitral insufficiency (MI). The examination included electrocardiogram (ECG), 24-hour ECG monitoring, heart X-ray with cardiothoracic index calculation, echocardiography, and plasma C-reactive protein level measurement. The follow-up period lasted for 6 months.Results. In both groups, clinical and hemodynamic parameters had improved, including left ventricular (LV) diastolic function improvement. Conservative therapy was more effective in individuals with lower LV ejection fraction (EF) values, mitral ostium area >1,5 cm2, and left atrium size <60 mm. Heart valve pathology associated with atrial fibrillation was characterized by predominant heart chamber dilatation and reduced myocardial contractility. Conclusion. Lisinopril and bisoprolol therapy, individually dosed and lasting for 6 months, improved clinical status and heart structure and function in patients with RMD. The therapy was also well-tolerated