Nanointerfacial Layer Effect on Dielectric and Piezoelectric Responses in Chemical Solution-Derived Lead-Free Alkaline Niobate-Based Thin Films.

Since nonpiezoelectric interfacial layers even at the nanoscale significantly affect the performance of lead-free piezoelectric thin films, the quantitative characterization of property changes of thin films due to interfacial layers is of great importance and should be precisely undertaken for piezoelectric microelectromechanical system (MEMS) and nanoelectromechanical system (NEMS) devices. In contrast to widely accepted concepts for interfacial layer thickness estimation based on the existing series capacitor model, we find that the interfacial layer thickness at the top and the bottom interfaces is clearly different in chemical solution deposition (CSD)-derived (K0.5,Na0.5)(Mn0.005,Nb0.995)O3 (KNMN) thin films. Interestingly, the thickness of the bottom interface increases linearly with increasing thin-film thickness, while the thickness of the top interface is constant regardless of the thin-film thickness. In this work, nanointerfacial layer effects of CSD-derived KNMN thin films are theoretically and experimentally addressed in a combinatorial way using a modified series capacitor model. The obtained information is used to envisage the origins and the mechanisms of nonpiezoelectric interfacial layers and associated dielectric and ferroelectric properties of KNMN thin films. Our research connects macroscopic properties with microscopic origins and is greatly facilitated by separating intrinsic and extrinsic contributions to phenomenological behaviors, as well as engineering interface-related properties of the films. We believe these studies to be crucial for the further development and applications of KNN-based lead-free piezoelectric devices, which also open the door to future studies on other lead-free piezoelectric material systems for practical MEMS and NEMS applications.

Flexible Pb(Zr0.52Ti0.48)O3 Films for a Hybrid Piezoelectric-Pyroelectric Nanogenerator under Harsh Environments.

In spite of extremely high piezoelectric and pyroelectric coefficients, there are few reports on flexible ferroelectric perovskite film based nanogenerators (NGs). Here, we report the successful growth of a flexible Pb(Zr0.52Ti0.48)O3 (PZT) film and its application to hybrid piezoelectric-pyroelectric NG. A highly flexible Ni-Cr metal foil substrate with a conductive LaNiO3 bottom electrode enables the growth of flexible PZT film having high piezoelectric (140 pC/N) and pyroelectric (50 nC/cm(2)K) coefficients at room temperature. The flexible PZT-based NG effectively scavenges mechanical vibration and thermal fluctuation from sources ranging from the human body to the surroundings such as wind. Furthermore, it stably generates electric current even at elevated temperatures of 100 °C, relative humidity of 70%, and pH of 13 by virtue of its high Curie temperature and strong resistance for water and base. As proof of power generation under harsh environments, we demonstrate the generation of extremely high current at the exhaust pipe of a car, where hot CO and CO2 gases are rapidly expelled to air. This work expands the application of flexible PZT film-based NG for the scavenging mechanical vibration and thermal fluctuation energies even at extreme conditions.

Antiferroelectric Thin-Film Capacitors with High Energy-Storage Densities, Low Energy Losses, and Fast Discharge Times.

We demonstrate a capacitor with high energy densities, low energy losses, fast discharge times, and high temperature stabilities, based on Pb(0.97)Y(0.02)[(Zr(0.6)Sn(0.4))(0.925)Ti(0.075)]O3 (PYZST) antiferroelectric thin-films. PYZST thin-films exhibited a high recoverable energy density of U(reco) = 21.0 J/cm(3) with a high energy-storage efficiency of η = 91.9% under an electric field of 1300 kV/cm, providing faster microsecond discharge times than those of commercial polypropylene capacitors. Moreover, PYZST thin-films exhibited high temperature stabilities with regard to their energy-storage properties over temperatures ranging from room temperature to 100 °C and also exhibited strong charge-discharge fatigue endurance up to 1 × 10(7) cycles.

Detection and identification of human papillomavirus types isolated from Korean patients with flat warts.

Flat warts, also called verruca planna (VP) or juvenile warts, are benign epithelial proliferations of the skin caused by infection with human papillomaviruses (HPV). Several HPV types are known to be associated with flat warts, and particularly HPV type 3 and 10 have been most frequently reported in other countries. In this study, for the detection and typing of human papillomavirus isolated from Korean patients with flat warts, polymerase chain reaction (PCR) and restriction endonuclease digestion were carried out with a set of restriction endonucleases, using the cloned HPV DNA and DNA from clinical specimens. A unique digestion pattern for HPV type 3 and 10, a form of miniature fingerprinting, enabled us to identify HPV type from the amplified fragments. A total of thirty clinical samples, as either frozen tissue or paraffin-embedded tissue, were investigated to verify the type. All the clinical samples except one were con-firmed to be type 3, one of the most frequently observed types in flat warts, and one sample was neither type 3 nor type 10. Further investigation of the unidentified sample by DNA sequencing and sequence alignment with other known HPV types revealed that the sample was a variant of HPV type 94, one of the EV-related HPVs, with the closest evolutionary distance to the HPV type 10 among the known flat wart-associated HPV types.

Transcriptional regulation of the mouse interleukin-2 receptor beta chain gene by Ets and Egr-1.

To clarify the mechanisms and factors involved in the regulation of mouse IL-2Rbeta gene expression, we isolated the 5'-flanking region of IL-2Rbeta gene and investigated the promoter activity. Here we elucidated the positive regulatory regions, the most potent of which are located between -50 to -30bp and -164 to -135bp. These regions contain a potentially functional Ets and Egr-1-binding sites whose mutations abrogate promoter activity. Data from electrophoretic mobility shift assay indicate that Ets and Egr-1, but not Sp1, bind to the positive regulatory regions, -50 to -30bp and -164 to -135bp, respectively. Furthermore, recruitment of Ets and Egr-1 at endogenous IL-2Rbeta promoter segments in an IL-2-dependent F7 cells was verified by the chromatin immunoprecipitation assay. This study for the first time delineates the molecular mechanisms underlying regulation of mouse IL-2Rbeta gene transcription by Ets family proteins, partially with Egr-1, and thereby further elucidates the molecular basis of lymphocyte activation and differentiation.