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We examine the effect of replacing calcium by zinc has on the transport properties of the BiSrCaCuO-2221 system. It is shown that the critical temperatures Tc of the Bi2Sr2CaCu2Ox(B1) and Bi2Sr2ZnCu2Oy(B2) samples are close (81K and 80.72 K). However, the resistivity ρ of the Bi2Sr2ZnCu2Oy sample increases considerably, and the ratio ρB2/ρB1≈10 at 100 K. We use the local pair model to analyze the mechanism behind the formation of excess conductivity in Bi2Sr2CaCu2Ox and Bi2Sr2ZnCu2Oy(B2), with consideration of the Aslamazov-Larkin theory near Tc. We determined the temperature T0 of the transition from the 2D fluctuation area to the 3D region (i.e., the 2D-3D crossover temperature). We calculated the coherence length of the fluctuation Cooper pairs along the c axis, ξc(0). It is shown that substituting Zn for Ca reduces ξc(0) by almost 1.5 times (4.8 Å and 3.3 Å, respectively), and also leads to a narrowing of both the pseudogap region and the superconducting fluctuation area near Tc. We determined the temperature dependence of the pseudogap Δ*T and Δ*(Tc). The increase of ρ, its specific temperature dependence and the significant decrease of T* in sample B2, all point to the destruction of local pairs at all high temperatures, i.e., to the suppression of the pseudogap by Zn doping. [ABSTRACT FROM AUTHOR]

Amorphous nonstoichiometric ZrO films of different composition have been synthesized by the method of ion-beam sputtering deposition of metallic zirconium in the presence of oxygen at different partial oxygen pressures in the growth zone, and their optical properties have been studied in the spectral range of 1.12-4.96 eV. It is found that light-absorbing films with metallic conductivity are formed at the partial oxygen pressure below 1.04 × 10 Pa and transparent films with dielectric conductivity are formed at the pressure above 1.50 × 10 Pa. It is shown that the spectral dependences of optical constants of ZrO films are described well by the corresponding dispersion models: the Cauchy polynomial model for films with dielectric conductivity and the Lorentz-Drude oscillator model for films with metallic conductivity. [ABSTRACT FROM AUTHOR]

Low-frequency (∼2 Hz) current self-oscillations were first obtained in a millimeter-sized two-terminal planar device with a vanadium dioxide (VO2) film. The film temperature distribution dynamics was investigated within one oscillation period. It was established that the formation and disappearance of a conductive channel occur in a film in less than 60 ms with oscillation period 560 ms. The experimentally observed temperature in the channel region reached 413 K, being understated due to a low infrared microscope performance (integration time 10 ms). The VO2 film temperature distribution dynamics was simulated by solving a 2D problem of the electric current flow and heat transfer in the film. The calculation showed that the thermally initiated resistance switching in the film occurs in less than 4 ms at a channel temperature reaching ∼1000 K. The experimental results and simulation are consistent with the current self-oscillation mechanism based on the current pinching and dielectric relaxation in the VO2 film at the metal-insulator phase transition. [ABSTRACT FROM AUTHOR]

Crystallographic parameters of TlInSSe solid solutions have been measured by X-ray diffraction. Dependences of the unit-cell parameters on the composition are determined. It is established that the values of parameters a, b, and c and the angle β decrease with an increase in x. It is shown that the TlInSSe system includes a continuous series of solid solutions based on the TlInSe compound with tetragonal symmetry at x values ≤ 0.4, while at x ≥ 0.6 solid solutions based on the TlInS compound with a monoclinic structure are formed. [ABSTRACT FROM AUTHOR]

Long-lived minima are detected at Tmin1 = 275 K and Tmin2 = 252 K in the ρ(T) curve of polycrystalline CdBa2Cu3O7-δ, which has a superconducting transition at 86.8 K. It is shown that the excess conductivity Δσ(T) near Tmin obeys the classical Aslamazov-Larkin fluctuation theory. This suggests that fluctuation Cooper pairs may develop in CdBa2Cu3O7-δ at T > Tc. The experimental data are used to calculate the coherence length ξc(0), the 2D-3D crossover temperature T0, and the interplanar pairing constants. The magnitude and temperature dependence of the pseudogap for a sample without the minima are found to be typical of cuprate HTSC materials. [ABSTRACT FROM AUTHOR]

A new superconducting ceramic material CdBa2Cu3O7-δ is obtained. It is found that the superconducting transition (at 86 K) is retained when yttrium is fully replaced by cadmium in the Y-Ba-Cu-O system. X-ray diffraction studies show that the crystalline structure is unchanged and the identified peaks coincide when Y is replaced by Cd in YBa2Cu3O7-δ. Besides a stable superconducting transition, a phase transition near 275 K was seen in the temperature dependence of the specific resistivity which shifted toward lower temperatures (252 K) and then disappeared completely over repeated measurement cycles. The thermal conductivity k of YBa2Cu3O7-δ and CdBa2Cu3O7-δ was found to vary little with temperature up to the superconducting transition. Substituting Cd for Y in the initial HTSC material led to a substantial increase in the lattice thermal conductivity. Measurements of the thermal emf showed that it is positive in YBa2Cu3O7-δ and negative in CdBa2Cu3O7-δ. [ABSTRACT FROM AUTHOR]

Optical characteristics of the HfO2 − xN x and TiO2 − xN x films obtained by reactive ion beam sputtering have been investigated by spectral ellipsometry. The chemical composition of the films was determined using X-ray photoelectron spectroscopy. The nitrogen content in the oxynitride films (determined by the N2/O2 ratio in the gas mixture during synthesis) reached ≈9 at % for TiO2 − xN x and ≈ 6 at % for HfO2 − xN x. It is found that the dispersion relations n(λ) and k(λ) for the TiO2 − xN x films change from those characteristic of titanium dioxide to those typical of titanium nitride with an increase in the nitrogen content from 0 to ≈9 at %. The optical parameters of the HfO2 − xN x films depend weakly on the nitrogen content in the range 0–6 at %. [ABSTRACT FROM AUTHOR]

LnIn3S6 (Ln = La, Nd, Yb) crystals were grown by chemical vapor transport. All the LnIn3S6 compounds were shown to be isostructural and to crystallize in orthorhombic symmetry (sp. gr. Pbam, Z = 4; a = 4.06-3.80 Å, b = 11.84-11.62 Å, c = 21.35-20.94 Å). The LnIn3S6 compounds are n-type semiconductors, with a band gap increasing from 1.03 to 1.27 eV in going from LaIn3S6 to LuIn3S6. Current-voltage, current-light, and photocurrent measurements demonstrate that LaIn3S6, SmIn3S6, GdIn3S6, HoIn3S6, and DyIn3S6 crystals are photosensitive in the near-IR spectral region. [ABSTRACT FROM AUTHOR]

The composition of synthesized ceramic samples is investigated by x-ray phase analysis, and it is established that they are high-Tc superconducting Bi2Sr2ZnCu2Ox. It is found that the crystal structure is preserved. To investigate how the superconductivity of Bi–Sr–Ca–Cu–O is influenced by the substitution of calcium by zinc, measurements of the temperature dependence of the resistivity, thermal conductivity, and thermopower (Siebeck coefficient) are carried out. It is found that the substituted compound Bi2Sr2ZnCu2Ox retains its superconducting properties (T0=82 K). It is shown that substitution of Ca by Zn leads to an increase of the thermal conductivity. While the thermopower of Bi2Sr2CaCu2Ox shows p-type conductivity in the whole range of temperatures investigated, in Bi2Sr2ZnCu2Ox the type of the conductivity is changed to n-type. [ABSTRACT FROM AUTHOR]

A study of the influence of magnetic field on the thermal conductivity of Bi2Sr2CaCu2Ox is made. It is found that the thermal conductivity increases under the influence of magnetic field because the electronic part of the thermal conductivity increases on account of breaking of the Cooper pairs and a decrease of the phonon-vortex scattering. [ABSTRACT FROM AUTHOR]

The optical properties, interface structure, and thermal stability of the ZrO2 films grown on Si(100) were investigated in detail. A 2 nm thick interfacial layer (IL) is formed at the ZrO2–Si interface for the as-grown ZrO2. The optical constants of ZrO2 films and IL correspond to amorphous-ZrO2 and amorphous-SiO2, respectively. The oxidation and IL growth at 900 °C, as a function of annealing time, exhibit a two-step behavior with a slow and a fast growth-rate zones. The transition from a zone of slow to fast rate is attributed to structurally modified ZrO2 facilitating the faster oxygen transport to the ZrO2/Si interface. [ABSTRACT FROM AUTHOR]

Ln3In5S12 compounds were characterized by physicochemical analysis and electrical measurements. All the compounds studied crystallize in monoclinic symmetry and are isostructural. In the series La3In5S12–Lu3In5S12 , the lattice parameters vary in the ranges a = 11.36–10.74 Å, b = 21.49–20.94 Å, c = 4.06–3.72 Å, and β = 98.8°–98.4°. The photoelectric properties of Ho3In5S12 crystals doped with Sn, Zn, Cu, and Cd were studied at 77 and 300 K. The Cd-doped crystals showed no appreciable photoresponse around the fundamental absorption edge. [ABSTRACT FROM AUTHOR]

Currently, a new generation of high-speed, information-intensive resistive memory based on nonstoichiometric dielectrics is being developed. The electron structure of nonstoichiometric silicon oxide SiOx is set by the value of parameter x. It is found that the treatment of thermal SiO2 in hydrogen plasma electron cyclotron resonance leads to the enrichment of silicon oxide with excess silicon, which in turn leads to the appearance of electron and hole traps in SiOx. SiOx conductivity is bipolar: electrons are injected from negatively biased silicon and holes are injected from positively biased silicon. Cathodoluminescence (CL) experiments confirm the assumption that the traps in SiOx are due to the excess silicon. p++-Si(100)/SiOx/Ni memristor metal-dielectric-semiconductor (MDS) structures are fabricated based on the developed procedure for the preparation of nonstoichiometric oxide in hydrogen plasma of electron cyclotron resonance. Such structures have the properties of resistive switching of SiOx that do not require a forming operation. [ABSTRACT FROM AUTHOR]

The problem of postoperative cognitive dysfunction today remains extremely relevant. One way to protect the brain is to use drugs that increase tolerance to intraoperative ischemia. The aim of this study is compare protective effects on brain during endarterectomy in terms of intravenous (propofol) and inhalation (desflurane) anesthesia. The study included patients over 65 with carotid atherosclerosis(Stenosis>70%) All patient were divided in two groups. Both groups underwent standard anesthesia induction with fentanyl (10 mcg/kg), propofol (2,0 mg/kg), and pancuronium bromide (0.1 mg/kg) In group D anesthesia was maintained on O2/air/ desflurane at concentrations up to 1.3 MAC and in group P by continuous infusion of propofol. Serum level of baseline protein S100B (the possibility of using S100b, as a marker and prognostic index for brain tissue damage during ischemic stroke has been proven [1,2] before surgery (T1), immediately after surgery (T2), and day after surgery(T3) was evaluated in all patients. All patients were continuously monitored for Heart rate, invasive blood pressure, SpO2, urine output, BIS index, capnography, brain dopplerography, nasopharyngeal temperature, and arterial blood gases. During the clamping of the carotid vessels, sympathomimetic support with norepinephrine was used to achieve MBP in the region of 100 mm Hg if required. The concentration of 100b in both groups did not differ at T1. The serum level of s100B at the T2 and T3 was significantly higher in group P (mediana 0,12 ng/l for group D vs 0,30 ng/l for group P in T2 (p = 0,002)); (mediana 0,15 ng/l for group D vs 0,44 ng/l for group P in T3 (p = 0,001)) The serum level of the S100b marker in the postoperative period was significantly higher when TIVA was performed. Probably desflurane has pharmacological protective properties on the brain, but it requires additional analysis. [ABSTRACT FROM AUTHOR]