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The (La0.3Pr0.7)1-xCaxCrO3 (x = 0, 0.1, 0.3 and 0.5) ceramics have been synthesized by a sol-gel method. The compounds crystalize in orthorhombic structure with space group Pnma at room temperature. The magnetic measurements confirm that the materials form canted antiferromagnetic (AFM) ordering from 254.1, 231.2, 118.5, 49.3 K for the samples of x = 0, 0.1, 0.3 and 0.5, accompanied by a spin reorientation transition at 191.4, 145.1, 55.8, 38.9 K because of the Pr3+-Cr3+ interaction. Meanwhile, a positive exchange bias effect is observed due to the antiparallel coupling between the Pr3+ and the canted AFM structure of Cr3+. The Neel temperature, compensation temperature as well as the coupling strength of Pr3+-Cr3+ monotonously decrease with the increase of Ca2+ concentration. For the samples of x = 0.1 and 0.3, there exists a field induced Pr3+-Pr3+ AFM ordering. By means of dielectric measurements, large permittivity at room temperature and dielectric relaxation are observed in all the samples. The permittivity is decreased and dielectric relaxation moves to low temperature range with the increase of Ca2+ concentration. A relaxor-like ferroelectric transition is observed in the measuring temperature range in Ca2+ doped samples.

In this study, we designed a novel magnetic semiconductor Sr2FeMoO6/SrMoO4 with a sharp metal-insulator transition based on the spin-glass freezing and antiferromagnetic transition behavior, which has been confirmed by various magnetic and transport measurements. To investigate the charge transport mechanisms of the sample, the electrical resistivities have been measured over a wide range of temperatures from 400 K down to liquid helium temperatures under different magnetic fields. The typical semiconductor behavior of the sample is observed. The relatively high conduction behavior is blocked below 80 K, and thereafter into the insulator state. The Vogel-Fulcher and the Mott variable-range-hopping (VRH) law are also used to study its conduction features and the relationship between magnetic and electrical properties. The spin-glass like component around the Sr2FeMoO6 crystal is initially observed by TEM and this provides a robust evidence able to verify the results from magnetic measurements. The novel features of the metal-insulator transition shielding external magnetic effects in highly disordered Sr2FeMoO6 double perovskite is dominantly controlled by a new spin-valve-system present in the spin-glass layers. Our insights into the role of the B-site disorder, spin-glass layer around the soft ferromagnetic grains, grain boundaries, and non-magnetic second phase effects demonstrate how the static and dynamic properties of magnetic materials might be tuned by designing the composition with a high B-site cation disordered matrix ferromagnetic material.

The La0.5Pr0.5Cr1−xFexO3 (x = 0, 0.1, 0.3 and 0.5) ceramics are synthesized by a citric acid sol-gel method. The crystal structure, morphology, chemical composition and magnetic properties are studied. The X-ray diffraction patterns show that the ceramics crystalize in orthorhombic structure with space group Pnma. The Rietveld refinement results indicate that the lattice parameters get larger with the increase of Fe3+ doping. By means of magnetic measurements, negative magnetization in positive magnetic field is obtained with the decrease of temperature and positive exchange bias effect is observed after field cooling process in La0.5Pr0.5CrO3. When doping with Fe3+ at the Cr3+ sites, the negative magnetization disappears and the positive exchange bias effect transforms to negative. Meanwhile, the negative exchange bias field gradually decreases and vanishes when the doping value of x reaches 0.5. Based on the positive exchange bias effect, an abnormal magnetic switching phenomenon is obtained without changing the direction of the external field after field cooling process.

The epithelial and epidermal innate cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) have pivotal roles in the initiation of allergic inflammation in asthma and atopic dermatitis (AD). However, the mechanism by which the expression of these innate cytokines is regulated remains unclear. Intelectin (ITLN) is expressed in airway epithelial cells and promotes allergic airway inflammation. We hypothesized that ITLN is required for allergen-induced IL-25, IL-33, and TSLP expression. In two asthma models, Itln knockdown reduced allergen-induced increases in Il-25, Il-33, and Tslp and development of type 2 response, eosinophilic inflammation, mucus overproduction, and airway hyperresponsiveness. Itln knockdown also inhibited house dust mite (HDM)-induced early upregulation of Il-25, Il-33, and Tslp in a model solely inducing airway sensitization. Using human airway epithelial cells, we demonstrated that HDM-induced increases in ITLN led to phosphorylation of epidermal growth factor receptor and extracellular-signal regulated kinase, which were required for induction of IL-25, IL-33, and TSLP expression. In two AD models, Itln knockdown suppressed expression of Il-33, Tslp, and Th2 cytokines and eosinophilic inflammation. In humans, ITLN1 expression was significantly increased in asthmatic airways and in lesional skin of AD. We conclude that ITLN contributes to allergen-induced Il-25, Il-33, and Tslp expression in asthma and AD.

The Dy3+ doped SmCrO3 polycrystalline ceramics are prepared by solid state method. The structure and magnetic properties are investigated. All samples show orthorhombic structure with space group Pnma. Three magnetic transitions are detected in Dy3+ doped SmCrO3 samples, which arise from the Cr3+-Cr3+ interactions and the spin reorientation of Cr3+, respectively. Both field cooled (FC) and zero field cooled (ZFC) exchange bias (EB) effects are observed in the prepared Sm1-xDyxCrO3 (x = 0 − 0.5) samples below the spin reorientation temperature (TSR), and the EB field (HEB) increases dramatically below TSR. With the increase of the doping level, the HEB is depressed. Three anomalous variations of magnetic entropy change (ΔSM) derived from the isothermal magnetization are observed, which are consistent with the magnetic transitions. Compared with the ΔSM after ZFC processes, the anomalous variations of ΔSM at ~25 K almost disappear after FC processes due to the enhanced unidirectional anisotropy, and no obvious influence is observed for the other two anomalous variations after FC processes.

Polycrystalline R 3 Fe 5 O 12 (R = Eu, Gd) ceramics are synthesized by a sol-gel method. The X-ray diffraction patterns show that both materials exhibit the same cubic structure with space group Ia 3 ¯ d . The dielectric behaviors and impedance spectra in the frequency range from 100 Hz to 10 MHz are investigated at different temperatures from 300 K to 700 K. The materials exhibit relatively large dielectric permittivity and low dielectric loss in a wide temperature and frequency range. Two dielectric relaxation processes are observed in the measurements. The high frequency relaxation is shown to originate from the electrons hopping between Fe 2+ and Fe 3+ , while the low frequency relaxation most likely arises from the doubly ionized oxygen vacancies. The impedance spectra indicate that the ceramics are electrically heterogeneous consisting of semiconducting grains and insulating grain boundaries (corresponding to the high and low frequency electrical responses, respectively), and the heterogeneous structures play important roles in the dielectric properties.

A series of multiferroic (1− x )BiFeO 3 − x (Bi 0.5 Na 0.5 )TiO 3 (BF–BNT) ( x = 0 − 0.6) solid solution ceramics were prepared by a sol–gel method. The XRD results show that increasing BNT content induce a gradual phase transformation from rhombohedral to pseudocubic structure near x = 0.4. Compared with pure BiFeO 3 , superior multiferroic properties are obtained for x = 0.3 with remnant polarization P r = 1.49 μC/cm 2 and saturated magnetization M s = 0.51 emu/g. Importantly, the paramagnetic (PM) to ferromagnetic (FM) transition is observed for the solutions, and the Curie temperature ( T C ) can be tuned by varying the content of BNT. This observed FM ordering is discussed in terms of the possible existence of the long-range superexchange interaction of Fe 3+ –O–Ti–O–Fe 3+ in the chemically ordered regions.

The structural, magnetic and ferroelectric properties of the (1-x)BiFeO3-xSrTiO3 (0 ≤ x ≤ 1.0) solid solutions synthesized by a modified Pechini method are investigated. Structure phase transition from rhombohedral to cubic phase was found with x increasing from the X-ray diffraction pattern. Compared with antiferromagnetic BiFeO3 compound, BFST-x (0.1 ≤ x ≤ 0.4) ceramics show ferromagnetism at room temperature, with their remnant magnetization (Mr) and coercive field (HC) strongly dependent on the content of SrTiO3. Moreover, appropriate SrTiO3 solution with BiFeO3 significantly reduces electric leakage and enhances electrical polarization. Among all the samples, the x = 0.2 samples shows the optimal ferromagnetism with Mr ～ 0.10 emu/g and the x = 0.3 samples the optimal ferroelectricity with Pr ～ 7.3 μC/cm2 at room temperature.

La 0.4 Sr 0.6 Ti 1− x Ni x O 3−δ powders with x =0 and 2% were synthesized by the sol–gel method and characterized by a variety of techniques. We mainly investigate the effect of annealing conditions on the structural and magnetic properties of La 0.4 Sr 0.6 Ti 1− x Ni x O 3−δ powders. X-ray diffraction and transmission electron microscopy studies indicate all samples annealed at high temperature ( T >873 K) are single phase and no secondary magnetic phase in this study. By the commercial physical properties measurements system (PPMS), the sample with x =0 exhibits diamagnetic behavior, whereas all the samples with x =2% are found to be ferromagnetic even at room temperature. With the increase of annealing temperature, the ferromagnetism of the samples increases initially, and then it decreases after reaching the maximum value. The structural defects such as oxygen vacancies mediated mechanism is reasonable explanation of the magnetic properties in the present results.

Analysis of various existing correlations including a three-zone evaporation model is made using a comparison with recent experimental results obtained in this study. Flow boiling heat transfer experiments were conducted with two stainless steel tubes of internal diameter 4.26 mm and 2.01 mm. The working fluid was R134a and parameters were varied in the range: mass flux 100–500 kg/m2s; pressure 8–12 bar; quality up to 0.9; heat flux 13–150 kW/m2. The local heat transfer coefficient was independent of vapour quality when this was less than about 40–50% in the 4.26 mm tube and 20–30% in the 2.01 mm tube. Local transient dryout was deduced when the quality was above these values. Furthermore, at high heat flux values the heat transfer coefficient decreased with vapour quality for the entire quality range indicating early occurrence of dryout. Existing correlations, which are based on large tube boiling processes, do not predict the present small diameter data to a satisfactory degree. A better agreement is observed with the recent, state-of-the-art, three-zone evaporation model. However, the model does not predict the effect of diameter and the partial dryout. Nevertheless, the observation suggests that the flow pattern based modelling approach performs at least as well as empirical correlations that are based on macroscale modelling. Aspects of the model that need further consideration are also proposed in this study.

Boiling heat transfer in small diameter tubes has been experimentally investigated using R134a as the working fluid. The heat transfer experiments were conducted with two stainless steel tubes of internal diameter 4.26 and 2.01 mm respectively. Other parameters were varied in the range: mass flux 100–500 kg/m2 s; pressure 8–12 bar; quality up to 0.9; heat flux 13–150 kW/m2. It was found that the nucleate boiling is dominant when the vapour quality is less than about 40–50% for the 4.26 mm tube and 20–30% for the 2.01 mm tube. Above these quality values, heat transfer coefficients decrease with vapour quality. Furthermore, this decrease occurs for the entire quality range at high heat flux values. Flow visualization experiments were carried out using the same experimental facility with Pyrex glass tubes. A flow pattern map was obtained at a system pressure of 10 bar and tube diameter of 4.26 mm.

A series of solid solution ceramics of (1 − x)BiFeO3–xNa0.5K0.5NbO3 (0.06 ≤ x ≤ 0.30) were successfully synthesized by Pechini method. The structural, magnetic and ferroelectric properties were investigated. The ceramics presented single phase perovskite structure, in which the transformation from rhombohedral to tetragonal symmetry occurred at x = 0.15. The room temperature ferromagnetism was observed in the samples of x ≤ 0.15 with rhombohedral structure, whereas the ferromagnetism disappeared as x increased. The enhanced ferroelectric property was observed, and the remnant polarization and coercive electric field could get 1.83 μC/cm2 and 11.2 kV/cm for the sample of x = 0.18. Moreover, magnetodielectric effect was investigated, revealing the coupling between the magnetic and electric orders essential for the multiferroic materials.

The Fe-doped CuO nanopowders (Cu0.95Fe0.05O) were prepared by the sol–gel and the co-precipitation methods. The effects of synthesis methods on the structure, magnetic property and exchange bias effect of Cu0.95Fe0.05O nanopowders were investigated. The microstructure and magnetic properties of the two types of nanopowders were characterized by X-ray diffraction and physics property measuring systems, respectively. It was found that the sol–gel method tended to lead the formation of CuFe2O4 phase, which dominated the magnetic behaviors of the sample; the co-precipitation tended to lead larger exchange bias field at low temperature in samples, comparing with sol–gel method.

The second stage turbine vanes of a recently developed high performance jet aero-engine were cast using a Ni 3 Al based alloy IC-6, and then coated with NiCrAlYSi by vacuum arc deposition. After a 379 h engine test, the morphology, microstructure, phase structure and chemical composition of the coating were examined and analyzed by scanning electron microscopy with X-ray energy dispersion spectrometer, X-ray diffraction and electron probe microanalysis techniques. The analytical emphasis was placed on the effect of black spots which appeared on the coating surface after the test on the coating and base alloy IC-6. In addition, the origin of black spots was intensely investigated.The results indicated that the black spots were a kind of high-temperature hot corrosion caused by Na 2 SO 4 melt salt from the combusted gases of the engine, the existence of black spots accelerated the internal oxidation of the coating, but had not impaired the base alloy after 379 h engine operation. It may be summarized that NiCrAlYSi coating can provide an effective protection against oxidation and corrosion of base alloy IC-6 at elevated temperature of the present test.

We examined the Sun's shadow by 10 TeV cosmic rays observed with the Tibet air shower array during the period from 1991 through 1997. The results suggest that there is a causal relation between the shadow's movement and the changing inclination of the heliospheric current sheet of the large-scale solar magnetic field. Thus, further observations with higher statistics may provide direct information on the relation between a time variation of the large-scale structure of the solar and interplanetary magnetic fields and the phase of solar activity cycle.

A new experiment to observe gamma rays around 100 TeV at Yanbajing (4300 m) in Tibet, China is planned by a collaboration between China and Japan. To study the feasibility of this experiment a test array was built at Mt. Norikura in Japan. Preliminary results from a search for gamma rays from Cyg X-3 and Her X-1 observed by this air shower array showed the upper limit fluxes of 5.6 × 10 −13 cm −2 s −1 and 3.0 × 10 −13 cm −2 s −1 with a 95% confidence level above TeV, respectively. At the first step experiment we will set up 65 scintillation counters in Tibet. An angular resolution of the apparatus will be better than 1° at an energy of 100 TeV. The detectors are monitored by a nitrogen laser system automatically which guarantees a long term quality of the data.