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A giant negative electrocaloric (EC) effect in a PbZrO3/(0.88BaTiO3-0.12 Bi(Mg1/2,Ti1/2)O3) (PZ/(BT-BMT)) multilayered composite ferroelectric (MCFE) thin film which is grown on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method is investigated in this work. The negative EC effect in the PZ/(BMT-BT) MCFE thin film is greatly higher than that in the PZ AFE thin film with an adiabatic temperature change (ATC) ΔT = 1.5 K. The ATC ΔT of the PZ/(BMT-BT) MCFE thin film is -32 K under the applied electric field change ΔE = 1151 kV/cm. The result is conducive to enhance the EC refrigeration efficiency greatly. [ABSTRACT FROM AUTHOR]

Hepatitis E virus recombinant genomes transcribed in vitro from two cDNA clones differing by two nucleotides were infectious for chimpanzees. However, one cDNA clone encoded a virus that was attenuated for chimpanzees and unable to infect rhesus monkeys. The second cDNA clone encoded a virus that infected both chimpanzees and rhesus monkeys and caused acute hepatitis in both. One mutation differentiating the two clones identified a cisreactive element that appeared to overlap the 3' end of the capsid gene and part of the 3' noncoding region. Capping of the RNA transcripts was essential for infectivity.

By using ionic implantation and wafer bonding technologies, we peeled off a single-crystal LiNbO3 thin film in the atomic-layer smoothness from the surface of a bulk Z-cut LiNbO3 single crystal. X-ray diffraction patterns showed only (00l) orientation of the film. From positive-up-negative-down pulse characterization, we measured domain switching current transients under various short-pulse voltages, where we observed domain switching currents to occur separately at time after initial capacitor charging currents. This is similar to early observations in bulk ferroelectric single crystals, where apparent positive/negative coercive fields of domain switching determined from polarization-electric field hysteresis loops always equal maximum/minimum applied fields. However, after pulse stressing of the film for more than 1000 cycles, the domain switching speed is accelerated, where domain switching current overlaps with the initial capacitor charging current with a well-defined coercive field independent of the applied-field strength. Finally, we simulated the whole domain switching current transients with the assumption of the resistance degradation across interfacial passive layers between the film and electrodes. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The current study was designed to investigate the functionality of lncRNA CCHE1 in nasopharyngeal carcinoma. MATERIALS AND METHODS: MiRNA levels of lncRNA CCHE1 were examined by RT-qPCR. CCK8 assay and colony formation assay were together performed to detect cell proliferation viability. Furthermore, wound healing assay and transwell assay were respectively conducted to assess cell migration and invasion. In addition, proteins related to MEK/ERK/c-MYC pathway were detected by Western blot. RESULTS: Elevated levels of CCHE1 were verified in NPC cell lines. Downregulation of CCHE1 significantly inhibited tumor growth and suppressed A549 cell proliferation, migration and invasion. MEK/ERK/c-MYC pathway was activated in nasopharyngeal carcinoma. Treatment of PD98059 (MEK inhibitor) or SCH772984 (ERK inhibitor) reversed the effects of CCHE1 on cell proliferation, migration and invasion in NPC. CONCLUSIONS: The present study suggested that downregulation of lncRNA CCHE1 could inhibit cell proliferation, migration and invasion by suppressing MEK/ERK/c-MYC pathway in nasopharyngeal carcinoma. [ABSTRACT FROM AUTHOR]

Perovskite Aurivillius structure Bi5Ti3FeO15 (BTF) polycrystalline thin films were prepared by a chemical solution deposition route. The microstructure, electrical, and magnetic properties were investigated and in particular the optical properties of the BTF films were addressed. The coexistence of the ferroelectric and weak ferromagnetic properties at room temperature demonstrates the multiferroic behavior of the BTF films. The optical dielectric functions in the photon energy range of 1.13-4.13 eV have been extracted by fitting the experimental data in terms of the Tauc-Lorentz and Cauchy models. A direct interband transition is allowed and the energy bandgap is determined to be ∼3.3 eV for the BTF films. The weak absorption below the bandgap edge was observed and described by the Urbach band tail rule. Finally, the optical dispersion behaviors of the BTF films in the transparent region were explained using a single oscillator model. [ABSTRACT FROM AUTHOR]

The 2 mol % Mn doped Pb0.5Sr0.5TiO3 films were fabricated on sapphire substrates by chemical solution deposition. The complex dielectric functions and optical parameters of the films determined by transmittance spectroscopy in a broad temperature range of 80-500 K were investigated. Apparent thermally-driven band-gap energy shrinkage, line-width of interband electron transition broadening and the Urbach band tail behaviors were observed. The results can be mainly correlated with the renormalization of electronic band structure and band-gap energy due to the electron-phonon interaction, which is well established in terms of the Bose-Einstein model. [ABSTRACT FROM AUTHOR]

The highly (l00) oriented Pb(Zr0.5Ti0.5)O3 thin films with different Fe3+ doping concentrations were fabricated on LaNiO3-coated silicon substrates by chemical solution deposition. And the microstructure, ferroelectric, leakage, and magnetic properties were investigated. The results indicate that incorporation of Fe3+ into PZT thin films can promote the degree of the lattice distortion and greatly improve the surface roughness. In comparison with the pure PZT sample, the ferroelectric hysteresis loops of Fe-doped PZT samples demonstrate larger and larger polarizations and coercive fields with the increase in Fe3+ doping amount. Moreover, leakage mechanism of present films evolves from the space charge limited conduction to the “modified” space charge limited conduction, and then returns to the space charge limited conduction with increasing Fe3+ doping concentration. The occurrence of exchange bias in these Fe-doped PZT samples implies that the magnetic exchange interaction can be explained by the bound magnetic polaron model. [ABSTRACT FROM AUTHOR]

The ac field (Eac) amplitude dependence of dielectric response has been investigated for poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) relaxor terpolymer films. The frequency dependence of the temperature of the permittivity maximum Tm can be well described by the Vogel–Fulcher relation for Eac in the range from 1.33 to 80 MV/m. Tm remains nearly constant at an Eac level lower than 13.3 MV/m, and starts decreasing with Eac increases further. The two parameters fitting to the Vogel–Fulcher relation, freezing temperature Tf and activation energy Ea, vary little for Eac below 26.7 MV/m and then Tf decreases, while Ea increases for higher Eac level. [ABSTRACT FROM AUTHOR]

The dc bias dependence of dielectric properties has been investigated for poly (vinylindene fluoride-trifluoroethylene-chlorofluoroethylene) relaxor terpolymer films. The frequency dependence of the temperature of the permittivity maximum, Tm, was analyzed using the Vogel–Fulcher (VF) relation. Two threshold fields, ∼30 and 160 MV/m were found in the electric-field dependence of Tm. Tm shows a minimum at ∼30 MV/m and a maximum at ∼160 MV/m. The VF parameters activation energy Ea and freezing temperature Tf respectively show a maximum and a minimum at ∼25 MV/m. [ABSTRACT FROM AUTHOR]

In this work we studied 65-nm-thick poly(vinylidene fluoride-trifluoroethylene) ferroelectric polymers films grown by Langmuir–Blodgett onto silicon substrates. Three dielectric anomalies have been unambiguously evidenced. The high temperature one near 380 K corresponds to the ferroelectric-paraelectric transition. The low temperature one near 270 K which is characterized by a β relaxation is attributed to structural defects in the crystalline phase leading to inhomogeneous strains detected by x-ray diffraction. At approximately 320 K, a Debye-like relaxation is clearly evidenced. Possible origins for this later relaxation are discussed. [ABSTRACT FROM AUTHOR]

A series of Mn doped Pb0.5Sr0.5TiO3 (PSMT) films with dopant concentrations from 0 to 10 mol % was fabricated on (111) Pt/Ti/SiO2/Si substrates by chemical solution deposition. Their microstructure, ferroelectric, and dielectric properties were investigated, and Mn doping was found to have a significant influence on the properties of (Pb,Sr)TiO3 film. The improved microstructure with increased grain size, remnant polarization, dielectric permittivity and its tunability by dc electric field, and reduced coercive field and dielectric loss was observed in the Mn doped samples. A PSMT film with 0.5 mol % Mn dopants exhibits the optimum characteristics with maximal remnant polarization (2Pr=25.28 μC/cm2), dielectric permittivity (1427) and tunability (74.5%, at 100 kHz), and minimal dielectric loss (0.015) at 1 kHz. The improvement was attributed to the improved microstructure, enhanced displacement of polar ions, and, most importantly, the suppression of oxygen-vacancy-induced ferroelectric domain pinning, which was well verified in terms of Rayleigh law. Finally, the evolution of oxygen-vacancy concentration modulated by the Mn doping in PSMT films was discussed. [ABSTRACT FROM AUTHOR]

In this work we studied 90 nm thick copolymer thin films of vinylidene fluoride (70%) with trifluoroethylene (30%) grown by Langmuir–Blodgett onto silicon substrates. The effects of two different bottom electrodes, namely, Al and LaNiO3 (LNO) are investigated. A Debye-like relaxation near 320 K is enlarged by LNO bottom electrode. X-ray diffraction pattern attests that two different crystallographic structures coexist below 340 K in film deposited on LNO. Compared with Al electrode, LNO electrode strongly increases defects or gauche segments in film and further weakens properties of film. [ABSTRACT FROM AUTHOR]