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To explore the therapeutic effects of quercetin on rats with encephalitis, especially on cell apoptosis, and the levels of HMGB-1 and TLR-4.32 healthy rats were equally assigned into ZC group (healthy group), NY group (encephalitis group), DJ group (60 ml quercetin group), and GJ group (240 ml quercetin group) followed by analysis of cell apoptosis, brain tissue water content, neurons, HMGB-1, TLR-4 and other inflammatory factors.The ZC group showed normal neuron volume and equitable staining; compared with ZC group, NY group showed neuron volume shrinkage and chromatin condensation; the neuron and color in DJ group were slightly better than NY group; the neuron volume in GJ group increased significantly and chromatin is distributed evenly. TLR-4, IL-4, IL-6, HMGB-1 in ZC and DJ group were significantly lower than those in NY group (p0.05); IL-4, IL-6, HMGB-1 in GJ group significantly decreased compared with DJ group (p0.05); MMP-9 enzyme activity in ZC and DJ group was significantly lower than NY group (p0.05) with lower level in GJ group than DJ group (p0.05). The water content was higher in brain tissue of NY group than ZC group (p0.05) and lower in DJ group than NY group (p0.05) with lower level in GJ group than DJ and NY group (all p0.05). The hippocampal neurons and cortical neurons in ZC and DJ group were higher than those in NY group (p0.05) and elevated in GJ group compared with DJ group and NY group (p0.05).Quercetin is effective in treating encephalitis rats possibly through inhibition of neuronal cell apoptosis and level of HMGB-1 and TLR-4.

To investigate the prevalence and vertical transmission rate ofParturient women's venous blood samples and neonatal heel blood samples were collected in Wuhu City and prepared into filter-paper blood samples. The prevalence and vertical transmission rate ofThere were three positive samples detected in the 475 filter-paper blood samples from the parturient women, with a mean positive rate of 0.63%. The prevalence ofThere is

The measurement of soil total nitrogen (TN) by hyperspectral remote sensing provides an important tool for soil restoration programs in areas with subsided land caused by the extraction of natural resources. This study used the local correlation maximization-complementary superiority method (LCMCS) to establish TN prediction models by considering the relationship between spectral reflectance and TN based on spectral reflectance curves of soil samples collected from subsided land determined by synthetic aperture radar interferometry (InSAR) technology. Based on the 1655 selected effective bands of the optimal spectrum (OSP) of the first derivate differential of reciprocal logarithm ([log{1/R}]'), (correlation coefficients, P < 0.01), the optimal model of LCMCS method was obtained to determine the final model, which produced lower prediction errors (root mean square error of validation [RMSEV] = 0.89, mean relative error of validation [MREV] = 5.93%) when compared with models built by the local correlation maximization (LCM), complementary superiority (CS) and partial least squares regression (PLS) methods. The predictive effect of LCMCS model was optional in Cangzhou, Renqiu and Fengfeng District. Results indicate that the LCMCS method has great potential to monitor TN in subsided land caused by the extraction of natural resources including groundwater, oil and coal.

In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of E_{2g} phonons in the multiband superconductor MgB_{2} can be selectively enhanced by femtosecond laser pulses, leading to a transient control of the number of carriers in the σ-electronic subsystem. The nonequilibrium evolution of the material optical constants is followed in the spectral region sensitive to both the a- and c-axis plasma frequencies and modeled theoretically, revealing the details of the σ-π interband scattering mechanism in MgB_{2}.

In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of E_{2g} phonons in the multiband superconductor MgB_{2} can be selectively enhanced by femtosecond laser pulses, leading to a transient control of the number of carriers in the σ-electronic subsystem. The nonequilibrium evolution of the material optical constants is followed in the spectral region sensitive to both the a- and c-axis plasma frequencies and modeled theoretically, revealing the details of the σ-π interband scattering mechanism in MgB_{2}.

An impinging jet reactor was developed for the deposition of superconducting MgB2 thin films by hybrid physical–chemical vapor deposition, a technique that combines Mg evaporation with the thermal decomposition of B2H6 gas. A transport and chemistry model for boron film deposition from B2H6 was initially used to investigate the effect of carrier gas, Mg crucible temperature and gas flow rates on boron film growth rate and uniformity. The modeling studies, which were validated experimentally, demonstrated a reduction in B2H6 gas-phase depletion and an increased boron film growth rate using an argon carrier gas compared to hydrogen. The results were used to identify a suitable set of process conditions for MgB2 deposition in the impinging jet reactor. The deposition of polycrystalline MgB2 thin films that exhibited a transition temperature of 39.5 K was demonstrated at growth rates up to ∼50 μm/h.

The anisotropy of the dielectric function of c -axis oriented MgB 2 thin films has been revealed by a combined study of normal-incident reflectance and spectroscopic ellipsometry. The application of this procedure enabled us to determine the complete set of optical response functions and to show that the dominant effect responsible for the anisotropy is due to interband transitions, which distinctly screen the plasma edge depending on the polarization of incident radiation. The most important transition occurs at 23,800 cm − 1 and is polarized in the ab-plane. This is in good agreement with the results obtained previously for single crystals. Our results are also in a qualitative agreement with those obtained by band structure calculations.

Commensurate BaTiO3/SrTiO3 superlattices were grown by reactive molecular-beam epitaxy on four different substrates: TiO2-terminated (001) SrTiO3, (101) DyScO3, (101) GdScO3, and (101) SmScO3. With the aid of reflection high-energy electron diffraction (RHEED), precise single-monolayer doses of BaO, SrO, and TiO2 were deposited sequentially to create commensurate BaTiO3/SrTiO3 superlattices with a variety of periodicities. X-ray diffraction (XRD) measurements exhibit clear superlattice peaks at the expected positions. The rocking curve full width half-maximum of the superlattices was as narrow as 7 arc s (0.002°). High-resolution transmission electron microscopy reveals nearly atomically abrupt interfaces. Temperature-dependent ultraviolet Raman and XRD were used to reveal the paraelectric-to-ferroelectric transition temperature (TC). Our results demonstrate the importance of finite size and strain effects on the TC of BaTiO3/SrTiO3 superlattices. In addition to probing finite size and strain effects, these heterostructures may be relevant for novel phonon devices, including mirrors, filters, and cavities for coherent phonon generation and control.

We report on time-resolved, transient photoimpedance measurements performed on current-biased microbridges excited by 100-fs wide, 800-nm wavelength, and 76-MHz repetition-rate optical pulses. Our bridges had dimensions of 20 mum by 40 mum and were patterned by conventional photolithography and ion milling from 150-nm-thick, epitaxial MgB2 films grown by a hybrid physical-chemical vapor-deposition technique. For high-speed detection experiments, the microbridges were embedded into coplanar-strip transmission lines and connected to a 20-GHz-bandwidth sampling oscilloscope via a semirigid coaxial cable. The test structures were placed inside an optical cryostat and studies were performed in the temperature range between 15 K and 40 K. At temperatures, e.g., 20 K, far below the bridge critical temperature and under low optical excitation, large and fast (130 ps in duration) photoresponse transients were observed, which we associate with the kinetic-inductive (Cooper-pair breaking) mechanism. At temperatures approaching the MgB2 critical temperature and/or under intense light illumination, an additional slow component of the photoresponse with a nanosecond decay time was measured. We interpret this second photoimpedance component as a resistive response, resulting from the hot-electron heating effect. The observed picosecond kinetic photoresponse makes our MgB2 bridges attractive candidates for fast and efficient optical detectors and photon counters.

A new reactor configuration for the hybrid physical-chemical vapor deposition (HPCVD) of MgB2 thin films was developed. In this new design, the substrate is resistively heated and inversely mounted in the gas stream. The Mg supply is placed downstream of the substrate and is inductively heated. The dual-heater reactor is designed to enable the growth of MgB2 thin films at lower substrate temperatures, permit the growth of thick films and is amenable to scale-up for film deposition over larger substrate areas than the original HPCVD design. Computational fluid dynamics (CFD) based reactor modeling was used to simulate the gas flow, temperature and gas phase concentration profiles in the reactor in order to identify conditions suitable for film deposition. A study of boron thin film deposition from B2H6 in the dual-heater configuration was carried out and the experimental results were compared to CFD simulations which utilized a previously developed gas-phase and surface chemistry model to predict the growth rate. The boron film growth rate slightly decreased as the substrate temperature was increased from 650degC to 750deg C in both the experiments and model simulation. The modeling results indicate that boron deposition is limited by the mass transfer of BH3 to the substrate under these conditions and the temperature dependency arises due to the upstream depletion of the boron precursor. MgB2 films were grown at a substrate temperature of 710degC and Mg temperature of 720degC using the dual-heater configuration. The film properties were consistent with previously published results of MgB2 on sapphire in the original HPCVD configuration with a superconducting transition temperature, Tc, of 40.3 K and residual resistivity ratio (RRR) of 13.

We report properties of polycrystalline MgB2 films deposited on thin flexible yttium-stabilized zirconia (YSZ) substrates by hybrid physical-chemical vapor deposition. The MgB2 films show a transition temperature of 38.9 K with a narrow superconducting transition (0.1 K). The self-field critical current density in the films reaches 107 A/cm2 at low temperatures. These properties do not change after repeated bending over a radius of 10 mm. Low microwave surface resistance comparable to those obtained in epitaxial MgB2 films on single-crystalline sapphire substrate was observed. The result shows promise of polycrystalline MgB2 films for applications in superconducting digital circuits as well as in coated conductor wires.

High quality MgB2/insulator/Pb Josephson tunnel junctions with two different barriers were studied. The junctions were fabricated using MgB2 films grown by hybrid physical-chemical vapor deposition and the barriers were formed at different temperature regions. Both kinds of junctions show clear tunneling characteristics with clear Josephson supercurrent, high IcRN products, and the expected Ic(B) pattern. The junctions with barriers formed at 200 to 450degC have higher IcRN, larger MgB2 pi gap values, thinner barriers and higher barrier heights than the junctions with barriers formed over 700degC. In addition, some intermediate temperature barrier junctions show features due to the sigma gap of MgB2, which were not observed in the high temperature barrier junctions. High device yield indicates that the approaches to form tunnel barriers are promising for device fabrications.

The effect of growth conditions on the chemical vapor deposition of boron thin films from diborane (B2H6) was investigated using a combination of experimental studies and computational fluid dynamics-based reactor modeling. A multi-physics computational model was developed to simulate the thermal-fluid environment in the reactor. The proposed chemistry model incorporated into the simulations includes gas-phase decomposition and formation of B2H6 and surface adsorption and reaction of borane (BH3). The model accurately predicts the experimentally measured temperature and partial pressure dependence of the boron growth rate using the sticking coefficient of BH3 on the growth surface as the only adjustable parameter in the calculations. The results indicate that at lower growth temperatures ( 500 °C) the growth rate is limited by mass transfer of BH3 to the substrate surface. The studies of boron thin film growth are relevant to the deposition of superconducting MgB2 thin films, in which B2H6 is used as the boron precursor.

The knowledge of the surface resistance R s of superconducting thin film at microwave and terahertz (THz) regions is significant to design, make and assess superconducting microwave and THz electronic devices. In this paper we reported the R s of MgB2 films at microwave and THz measured with sapphire resonator technique and the time-domain THz spectroscopy, respectively. Some interesting results are revealed in the following: (1) A clear correlation is found between R s and normal-state resistivity right above T c, ρ0, i.e., R s decreases almost linearly with the decrease of ρ0. (2) A low residual R s, less than 50 μΩ at 18 GHz is achieved by different deposition techniques. In addition, between 10 and 14 K, MgB2 has the lowest R s compared with two other superconductors Nb3Sn and the high-temperature superconductor YBa2Cu3O7−δ(YBCO). (3) From THz measurement it is found that the R s of MgB2 up to around 1 THz is lower than that of copper and YBCO at the temperature below 25 K. (4) The frequency dependence of R s follows ω n , where ω is angular frequency, and n is power index. However, n changes from 1.9 at microwave to 1.5 at THz. The above results clearly give the evidences that MgB2 thin film, compared with other superconductors, is of advantage to make superconducting circuits working in the microwave and THz regions.

Carbon-doped MgB/sub 2/ thin films have been produced with hybrid physical-chemical vapor deposition (HPCVD) by adding a carbon-containing metalorganic magnesium precursor, bis(methylcyclopentadienyl)magnesium, to the carrier gas. The amount of the carbon added, thus the carbon content in the films, was controlled by the flow rate of a secondary hydrogen gas flow through the precursor bubbler. X-ray diffraction and electron microscopy showed that the carbon-doped MgB/sub 2/ films are textured with c-axis oriented columnar nano-grains and highly resistive amorphous areas at the grain boundaries. When the amount of carbon in the films increases, the resistivity increases dramatically while T/sub c/ decreases much more slowly as the current-carrying cross section is reduced by the grain boundaries. The temperature-dependent part of the resistivity, /spl Delta//spl rho//spl equiv//spl rho/(300 K)-/spl rho/(50 K), increases only modestly until the highly resistive grain boundaries completely cut off the conducting path. The impact of the reduced cross section on critical current density J/sub c/ is discussed.

We present here measurements carried out by using a dielectrically loaded copper cavity operating at 7 GHz on MgB/sub 2/ thin films synthesized by hybrid physical-chemical vapor deposition. Microwave data on samples having critical temperatures above 41 K, very low resistivity values, and residual resistivity ratio between 15 and 17, are presented. The dependence of the nonlinear surface losses and of the third order intermodulation products on the power feeding the cavity is analyzed, with the aim of shedding a light on the primary dissipation mechanisms. At low power, data from both power dependence and third order products seem to indicate that we are observing a nonlinear response which is inherent to the conventional s-wave nature of this novel compound. At intermediate-to-high circulating power values, vortex penetration appears to be the limiting mechanism for the power handling capability of MgB/sub 2/ films.

We report structural and transport proprieties of MgB/sub 2//MgO and MgB/sub 2//AlN multilayers for MgB/sub 2/ Josephson junctions. The MgB/sub 2/ layers were grown by hybrid physical chemical vapor deposition (HPCVD). The epitaxial MgB/sub 2//MgO/MgB/sub 2/ trilayers were grown in situ in the HPCVD system. The AlN layers were grown at room temperature by pulsed laser deposition, and the MgB/sub 2//AlN/MgB/sub 2/ trilayers were deposited ex situ with the deposition of the AlN layer between the depositions of the top and bottom MgB/sub 2/ layers. Although slightly less perfect than in films grown directly on sapphire and SiC substrates, excellent superconducting and transport properties were obtained in the MgB/sub 2/ layers in both heterostructures. The result addressed only the first of many issues about the adequacy of using MgO and AlN as the barrier materials for all-MgB/sub 2/ planar Josephson junctions, i.e. the ability to obtain good structural and superconducting properties in both electrode layers using the trilayer deposition process. It allows us to further investigate the conditions for better wetting and coverage of the insulator layers, as well as other critical issues in the fabrication of all-MgB/sub 2/ planar Josephson junctions.

The mixed state in c-axis oriented ultra-pure MgB/sub 2/ thin films and carbon-doped MgB/sub 2/ thin films produced by hybrid physical-chemical vapor deposition was studied using magneto-optical imaging (MOI) technique. In the ultra-pure MgB/sub 2/ films, a regular magnetic flux penetration pattern was observed, as expected from the Bean critical state model. This is in striking contrast to earlier MOI observations of MgB/sub 2/ films made by pulse laser deposition, where dentritic flux jumps were usually abundant at temperature below 10 K. In our carbon-doped MgB/sub 2/ thin films, similar dentritic flux jumps were also observed at low temperature and low applied magnetic field. It is evident that the dendritic flux jumps or stability of the film is strongly influenced by the material parameters of the films, rather than inherent in all MgB/sub 2/ thin films.

We have grown MgB/sub 2/ films at different substrate temperatures by hybrid physical-chemical vapor deposition. X-ray diffraction analysis shows epitaxial growth at all temperatures, as measured at the substrate surface, between 550-700/spl deg/C. An optimal deposition temperature was found around 650/spl deg/C, at which the rocking curve is the narrowest, the residual resistivity is the lowest, and T/sub c/ is the highest. For the films deposited at lower temperatures, the rocking curve broadens, indicating a decreasing quality of crystallinity. The residual resistivity increases but the superconducting transition temperature remains nearly constant around 40 K when the deposition temperature is decreased to 550/spl deg/C. The deposition of epitaxial films with excellent superconducting properties at low substrate temperatures is important for device and circuit processing utilizing MgB/sub 2/.

We have studied the degradation of MgB/sub 2/ thin films, grown by hybrid physical-chemical vapor deposition (HPCVD), by submerging MgB/sub 2/ films into de-ionized water at different temperatures. The thickness, room temperature resistance, and superconducting transition were measured as a function of time in water and the temperature of the water. Results show that the films degrade faster at room temperature than at 0/spl deg/C. The room temperature resistance increases with time. The thickness of the MgB/sub 2/ films decreases rapidly initially, but then saturates. The resultant material is amorphous and insulating. Both T/sub c/(onset) and T/sub c/(0) of the MgB/sub 2/ films decrease with time in water, while the superconducting transition become broader. The effects of the exposure to other solvents and photoresist were also studied, and it was found that isopropanol does not cause MgB/sub 2/ films to degrade.

We present a Raman spectroscopy study of the lattice-dynamical properties of the BaxSr1−xTiO3 thin films with x=0.05, 0.1, 0.2, 0.35, and 0.5 in the temperature range of 5–300K. Soft phonon modes were observed, and the temperature dependence of their frequencies and Raman intensities were investigated. The Raman spectra of the BaxSr1−xTiO3 films are compared with the single crystals of the same compositions. The essential differences in the lattice-dynamical properties of the thin films and single crystals are observed, such as the forbidden first-order Raman scattering in the films well above the phase-transition temperature in bulk, hardening of the soft phonon modes in films compared to crystals, and significantly larger range of the soft-mode overdamping in the films. On the other hand, the lattice-dynamics behavior in the BaxSr1−xTiO3 films is found similar to that of the relaxor ferroelectrics. Analogous to the relaxors, the presence of the polar nanoregions existing in the films at the temperatures...

The dependences of magnetic field penetration depth at zero temperature lambda(0), microwave surface resistance R(s) and pi -band energy gap at zero temperature Delta(pi)(0) on the normal-state resistivity fight above the critical, rho(0), were studied for MgB(2) thin films prepared by different temperature. techniques by employing a sapphire resonator technique. We found that the zero-temperature penetration depth lambda(0) data could be well fitted by lambda(L)(1 + xi(0)/l)(1/2) yielding a London penetration depth lambda(L) of 34.5 nm, where xi(0) is the coherence length, and l is the mean free path determined from rho(0). The surface resistance R(s) at 15 and 20 K increases roughly linearly with rho(0). The observed increase of Delta(pi)(0) with rho(0) and the decrease of T(c) indicate the expected effects of interband impurity scattering within an extended BCS approach. The low values of R(s) and lambda(0) in conjunction with the large coherence length for epitaxial films are potentially attractive for applications in electronics and microwave technology.

By measuring the field and temperature dependence of magnetization on systematically doped $La_{2-x}Sr_xCuO_4$ thin films, the critical current density $j_c(0)$ and the collective pinning energy $U_p(0)$ are determined in single vortex creep regime. Together with the published data of superfluid density, condensation energy and anisotropy, for the first time we derive the doping dependence of the coherence length or vortex core size in wide doping regime directly from the low temperature data. It is found that the coherence length drops in the underdoped region and increases in the overdoped side with the increase of hole concentration. The result in underdoped region clearly deviates from what expected by the pre-formed pairing model if one simply associates the pseudogap with the upper-critical field.

We have carried out thermodynamics studies of the Mg-B system with the calculation of phase diagrams (CALPHAD) modeling technique and found that the superconductor MgB/sub 2/ phase is thermodynamically stable only under fairly high Mg pressures at elevated temperatures. This has lead us to the investigation of chemical vapor deposition in which the pressure during the film deposition can be high. Although the initial effort on metal-organic chemical vapor deposition (MOCVD) was not successful due to carbon contamination, a unique hybrid physical-chemical vapor deposition (HPCVD) technique has successfully produced high quality in situ MgB/sub 2/ films. The epitaxially-grown MgB/sub 2/ films show high transition temperature and low resistivity comparable to the best bulk samples, and their surfaces are smooth. In this paper, the details of the technique and the results of the HPCVD films are presented.

A highly ordered grating pattern is observed in the SrRuO3 buffer layer in an SrTiO3/SrRuO3 bilayer system on (0 0 1) SrTiO3 substrate. By means of high-resolution transmission electron microscopy, the grating lines are found to consist of lattice defects and nanoscale precipitate particles. The particles are identified as pure ruthenium crystals. Correspondingly, Sr-rich Ruddlesden-Popper planar defects occur in the nearby area. This unusual film growth phenomenon may provide a novel way to fabricate ordered structures in oxide films for potential applications. (C) 2003 Elsevier Science B.V. All rights reserved.

The recently discovered superconductor MgB2 with Tc at 39 K has great potential in superconducting electronics. In this paper, we review the deposition techniques used for MgB2 thin films in the light of a thermodynamic study of the Mg-B system with the calculation of phase diagrams (CALPHAD) modeling technique. This thermodynamic study identifies a growth window in the pressure–temperature phase diagram, in which the magnesium pressure is very high for likely in situ growth temperatures. A Hybrid Physical–Chemical Vapor Deposition (HPCVD) technique that successfully achieves such a high Mg pressure is shown to produce in situ epitaxial MgB2 thin films with bulk superconducting properties.

The dielectric behavior of SrTiO3 (STO) thin films grown epitaxially on different substrates using pulsed laser ablation is reported in this article. The thickness of the SrRuO3 buffer layer, serving as an electrode, was varied from 500 to 5000 A, to study the dependence of dielectric properties of the STO films on the buffer layer thickness. Strains introduced during the high-temperature deposition of these films, seem to greatly influence the dielectric behavior observed in them in the form of loss peaks. This article also reports the results of tunability and the results of dielectric measurements are correlated to the strain in the films.

The recently discovered superconductor MgB2 with Tc at 39 K has great potential in superconducting microelectronics. Thermodynamics studies with the calculation of phase diagrams (CALPHAD) modelling technique show that due to the high volatility of Mg, MgB2 is only thermodynamically stable under fairly high Mg overpressures for likely in situ growth temperatures. This provides a helpful insight into the appropriate processing conditions for MgB2 thin films, including the identification of the pressure–temperature region for adsorption-controlled growth. The initial MgB2 thin films were made by pulsed laser deposition followed by in situ annealing. The cross-sectional transmission electron microscopy reveals a nanocrystalline mixture of textured MgO and MgB2 with very small grain sizes. A zero-resistance transition temperature of 34 K and a zero-field critical current density of 1.3 × 106 A cm−2 were obtained. The qualities of these films are limited by the thermodynamic stability conditions, which favour deposition techniques that can maintain a high flux of Mg.

Two types of stair-rod dislocation formed at junctions of {111} stacking faults in SrTiO3-SrRuO3 two-layer films on LaAlO3 substrates have been studied by high-resolution transmission electron microscopy. The first type, formed by the interaction of two stacking faults situated at the flat SrRuO3-LaAlO3 interface without any step, has a Burgers vector (a/3) . The other type, formed by the interaction of two stacking faults, of which one starts from the SrRuO3-LaAlO3interface area involving an interface step, has a Burgers vector (a/3) . The formation mechanism of the stair-rod dislocations and the effect of the step are discussed.

We have studied the Sr doping dependence of the superconducting properties of La/sub 2-x/Sr/sub x/CuO/sub 4+/spl delta// thin films grown by pulsed laser deposition over the range of 0/spl les/x/spl les/0.30. We found that the strain in the films depends on the Sr doping level. In 1000 /spl Aring/ La/sub 2-x/Sr/sub x/CuO/sub 4+/spl delta// films grown on 1000 /spl Aring/ SrLaAlO/sub 4/ buffer layer, the strain changes from compressive to tensile when m increases. For both compressive and tensile strain, films prepared in strongly oxidizing ozone/molecular oxygen mixture are superconducting for all Sr content with x/spl les/0.25. When the films are cooled in pure molecular oxygen the x dependence is similar to that in the bulk, although the transition temperature depends on the strain. The results suggest that the Sr content, epitaxial strain, and oxygenation conditions are all important factors influencing the superconductivity in La/sub 2-x/Sr/sub x/CuO/sub 4+/spl delta// thin films.

We present a systematic study of microwave nonlinearity, undertaken on different types of superconductors (Nb, NbN, MgB2 Y-1 beta a(2)Cu(3)O(7-delta)), in thin film form. Experiments are performed in a dielectrically loaded cavity operating at 7 GHz. The dependence of the surface impedance Z(s) and of the third order intermodulation (IMD) products on the power feeding the cavity is analysed, with the aim of shedding a light on the primary mechanisms of nonlinearity. Data from different superconductors are quantitatively compared.

We investigated the effect of alloying on the upper critical field Hc2 for 12 MgB2 films, in which disorder was introduced by growth, carbon doping or He-ion irradiation, finding a significant Hc2 enhancement in C-alloyed films, and an anomalous upward curvature of Hc2sTd. Record high values of Hc2 's4.2d

We present here measurements carried out by using a dielectrically loaded copper cavity operating at 7 GHz on MgB2 thin films synthesized by hybrid physical-chemical vapor deposition. Microwave data on samples having critical temperatures above 41 K, very low resistivity values, and residual resistivity ratio between 15 and 17, are presented. The dependence of the nonlinear surface losses and of the third order intermodulation products on the power feeding the cavity is analyzed, with the aim of shedding a light on the primary dissipation mechanisms. At low power, data from both power dependence and third order products seem to indicate that we are observing a nonlinear response which is inherent to the conventional s-wave nature of this novel compound. At intermediate-to-high circulating power values, vortex penetration appears to be the limiting mechanism for the power handling capability of MgB2 films.

We have investigated systematically the oxygen pressure dependences of the crystalline phases and the crystallographic orientations of BaTiO3 thin films by means of asymmetric rocking curves. Epitaxial BaTiO3 thin films were grown on SrTiO3 (001) substrates by pulsed laser deposition (PLD) under different oxygen pressures. The X-ray diffraction theta/2 theta scans showed no diffraction peaks from impurity phases or randomly oriented grains, indicating that the thin films were single phase BaTiO3. The XRD omega rocking curves indicated that the BaTiO3 thin films had a very high degree of crystallinity. The XRD phi scans showed that no in-plane misorientation existed in the BaTiO3 thin films. The results of asymmetric rocking curves showed that the BaTiO3 thin films grown under higher oxygen pressures(> 12 Pa) were tetragonal with a-axis orientation, those grown under lower oxygen pressures (