Novel Route for Enhancing Piezoelectricity of Ferroelectric Films: Controlling Nontrivial Polarization States in Pb(Zr, Ti)O3 Monodomain Superlattice Structure.

Artificial superlattice films made of Pb(Zr0.4Ti0.6)O3 and Pb(Zr0.6Ti0.4)O3 were investigated for their polarization states and piezoelectric properties theoretically and experimentally in this study. The developed theory predicts nontrivial polarization along neither [001] nor [111] directions in (111)-epitaxial monodomain superlattice films with uniform compressive strain. Such films were achieved via pulsed laser deposition. When the layer thickness is reduced to 3 nm, d33 becomes 128 ± 3.8 pm/V at 100 kV/cm and 71.3 ± 2.83 pm/V at 600 kV/cm, comparable to that of (111)-oriented Pb(Zr0.4Ti0.6)O3 or Pb(Zr0.6Ti0.4)O3 bulks and clearly exceeding that of the typical clamped films. The measurement agrees with the theoretical analysis, which reveals that the enhanced piezoelectricity is due to rotation of the nontrivial polarization. Furthermore, the theoretical study predicts an even larger d33 exceeding 300 pm/V for specific parameters in superlattice films with uniform tensile strain, which is promising for applications of microelectromechanical systems.

Unraveling the reasons behind lead phthalocyanine acting as a good absorber for near-infrared sensitive devices.

Lead phthalocyanine (PbPc) is well known to be used as a good near-infrared (NIR) light absorber for organic solar cells (OSCs) and photodetectors. The monoclinic and triclinic phases have been understood to absorb the visible and NIR regions, respectively, so far. In the present study, we demonstrated from the absorption spectra and theoretical analysis that the visible band considerably originates from not only the monoclinic but also the amorphous and triclinic phases, and revealed the exciton dynamics in the PbPc film from static/time-resolved photoluminescence (PL), which are first reported. By comparing the external quantum efficiency between PbPc- and ZnPc-based OSCs in relation to their structure, morphology, and optical (absorption and PL) characteristics, we unraveled the reasons behind the PbPc film used as a good absorber for NIR-sensitive devices.

Lenvatinib in patients with advanced or metastatic thymic carcinoma (REMORA): a multicentre, phase 2 trial.

BACKGROUND: Thymic carcinoma is a rare malignant disease and standard treatment for advanced or metastatic thymic carcinoma previously treated with platinum-based chemotherapy has not been established. Lenvatinib is a novel multi-targeted inhibitor of VEGFR, FGFR, RET, c-Kit, and other kinases. The aim of this trial was to assess the activity and safety of lenvatinib as a second-line treatment in thymic carcinoma. METHODS: This single-arm, phase 2 trial done in eight institutions in Japan (five cancer centres, two medical university hospitals, and one public hospital) enrolled patients with pathologically confirmed unresectable advanced or metastatic thymic carcinoma that progressed following at least one platinum-based chemotherapy. Key inclusion criteria were age 20 years or older, at least one measurable lesion as defined by the Response Evaluation Criteria in Solid Tumors version 1.1, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients received 24 mg of lenvatinib orally once daily in 4-week cycles until disease progression or occurrence of unacceptable adverse events. The primary endpoint was objective response rate evaluated at the data cutoff date (Feb 22, 2019), by independent central review in the intention-to-treat population. This trial is registered on JMACCT, JMA-IIA00285, and on UMIN-CTR, UMIN000026777. FINDINGS: Between April 21, 2017, and Feb 22, 2018, 42 patients were enrolled and all patients were included in the activity and safety analysis. The median follow-up period was 15·5 months (IQR 13·1-17·5). The objective response rate was 38% (90% CI 25·6-52·0, p<0·0001). 16 (38%) of 42 patients had a partial response and 24 (57%) had stable disease. The most frequent grade 3 treatment-related adverse events were hypertension (27 [64%]) and palmar-plantar erythrodysaesthesia syndrome (three [7%]). No patient died from adverse events. INTERPRETATION: The activity and safety of lenvatinib in patients with advanced or metastatic thymic carcinoma was confirmed. These results suggest that lenvatinib could become a standard treatment option for patients with previously treated advanced or metastatic thymic carcinoma. FUNDING: Center for Clinical Trials, Japan Medical Association.

Time-resolved X-ray diffraction system for study of Pb(Zr, Ti)O3 films under a temporal electric field at BL15XU, SPring-8.

We report on the use of a time-resolved X-ray diffraction system to study a piezoelectric material under a temporal electric field at the BL15XU NIMS beamline, at SPring-8 in Japan. By synchronizing focused X-rays onto a device under an applied electric field with a two-dimensional detector and measurements performed with respect to the synchrotron clock signal, we successfully observed shifts of the 222 Bragg peak of 750-nm-thick Pb(Zr, Ti)O3 films near time zero under a unipolar rectangular wave at 24 V. We expect that this system might be useful for understanding the piezoresponse, lattice dynamics, and domain switching dynamics of functional oxide thin films.

Asymmetric Michael Reaction of α-CF3 Thioester and α,ß-Unsaturated Aldehyde Catalyzed by Diphenylprolinol Silyl Ether.

Asymmetric Michael reaction of α-CF3 thioester and α,ß-unsaturated aldehyde is catalyzed by diphenylprolinol silyl ether to afford the trifluoromethyl substituted Michael product with excellent enantioselectivity. Although the Michael products were generated as a mixture of syn- and anti-isomers, they can be transformed to single isomers of other useful compounds, such as lactone, lactam, piperidine, dihydropyran containing trifluoromethyl groups, or fluoro substituents.

Significant effect of Mg-pressure-controlled annealing: non-stoichiometry and thermoelectric properties of Mg2-δSi1-xSbx.

Non-stoichiometry related to such an element with high vapor pressure as Mg has been difficult to control, despite its significant influence on the thermoelectric properties of the material. Here, Mg non-stoichiometry and the thermoelectric properties of Mg2-δSi1-xSbx (0 ≤ x ≤ 0.60) are investigated systematically by tuning the Mg partial pressure during annealing. The range of Mg non-stoichiometry Δδ depends on x since the Sb dopant induces Mg vacancies, which are partly filled by Mg atoms in the gas phase according to an equilibrium reaction. The defect association between the Mg vacancies and the Sb dopant decreases Δδ at high Sb contents. The maximum Δδ of 0.016, which corresponds to a carrier concentration range Δn of 4.9 × 1020 cm-3, is obtained at x = 0.10. The Seebeck coefficient shows a universal relationship with the carrier concentration, which can be explained by the DFT-calculated band structure within the rigid band approximation. The carrier mobility is reduced significantly as a result of carrier scattering at the Mg-poor grain boundaries. The vacancy formation at the Mg-site, in addition to Si-site substitution for Sb, effectively suppresses the lattice thermal conductivity. The low thermal conductivity on the Mg-poor side increases the maximum zT, while a high energy conversion efficiency is obtained on the Mg-rich side, owing to the high electrical conductivity and resultant large zT at low temperatures. Mg non-stoichiometry is a key factor in tuning the thermoelectric properties of Mg2Si-based materials and thus its control is essential.

Controlling factor of incoming plate hydration at the north-western Pacific margin.

Hydration of the subducting oceanic plate determines the amount of water transported from Earth's surface into its interior, and plate bending-related faulting (bend faulting) just prior to subduction is considered to promote hydration. Bend faulting shows significant spatial variation, but its contribution to hydration is still poorly understood. Here we present the results of controlled-source seismic surveys around the junction of the Japan and Kuril trenches. We found structural changes caused by bend faulting before subduction differed distinctly between both trenches and were well correlated with plate hydration after subduction, suggesting the bend faulting controls spatial variations in plate hydration. Differences in bend faulting are closely related to the angle between the current trench and the ancient spreading ridge, and the hydration is more extensive where this trench-ridge angle is oblique in the study area. Thus, we propose this angle is a major factor controlling plate hydration.

In-situ observation of ultrafast 90° domain switching under application of an electric field in (100)/(001)-oriented tetragonal epitaxial Pb(Zr0.4Ti0.6)O3 thin films.

Ferroelastic domain switching significantly affects piezoelectric properties in ferroelectric materials. The ferroelastic domain switching and the lattice deformation of both a-domains and c-domains under an applied electric field were investigated using in-situ synchrotron X-ray diffraction in conjunction with a high-speed pulse generator set up for epitaxial (100)/(001)-oriented tetragonal Pb(Zr0.4Ti0.6)O3 (PZT) films grown on (100) c SrRuO3//(100)KTaO3 substrates. The 004 peak (c-domain) position shifts to a lower 2θ angle, which demonstrates the elongation of the c-axis lattice parameter of the c-domain under an applied electric field. In contrast, the 400 peak (a-domain) shifts in the opposite direction (higher angle), thus indicating a decrease in the a-axis lattice parameter of the a-domain. 90° domain switching from (100) to (001) orientations (from a-domain to c-domain) was observed by a change in the intensities of the 400 and 004 diffraction peaks by applying a high-speed pulsed electric field 200 ns in width. This change also accompanied a tilt in the angles of each domain from the substrate surface normal direction. This behaviour proved that the 90° domain switched within 40 ns under a high-speed pulsed electric field. Direct observation of such high-speed switching opens the way to design piezo-MEMS devices for high-frequency operation.

Charge screening strategy for domain pattern control in nano-scale ferroelectric systems.

Strain engineering is a widespread strategy used to enhance performance of devices based on semiconductor thin films. In ferroelectrics strain engineering is used to control the domain pattern: When an epitaxial film is biaxially compressed, e.g. due to lattice mismatch with the substrate, the film displays out-of-plane, often strongly enhanced polarization, while stretching the film on the substrate results in in-plane polarization. However, this strategy is of a limited applicability in nanorods because of the small rod/substrate contact area. Here we demonstrate another strategy, in which the polar axis direction is controlled by charge screening. When charge screening is maintained by bottom and top metallization, the nanorods display an almost pure c-domain configuration (polarization perpendicular to the substrate); when the sidewalls of the nanorods are metallized too, a-domain formation prevails (polarization parallel to the substrate). Simulations of the depolarization fields under various boundary conditions support the experimental observations. The employed approach can be expanded to other low-dimensional nano-scale ferroelectric systems.

Fabrication of Tetragonal Pb(Zr,Ti)O3 Nanorods by Focused Ion Beam and Characterization of the Domain Structure.

It has been widely revealed and discussed that the properties of ferroelectric nanostructures vary with their dimensionality and size. The mechanical substrate clamping and the depolarization field are considered as major factors, which cause their unique properties. In this paper, we fabricated tetragonal {100}-Pb(Zr, Ti)O3 rods with 100 nm - 4 µm widths on Nb-doped SrTiO3 substrates by using focused ion beam, and characterized their domain structure by synchrotron micro X-ray diffraction. It was found that the clapping angle in the a/c-domain structure became larger with decreasing the rod width, which indicates the significant reduction of substrate clamping by fabricating narrow rods.

Halobaculum magnesiiphilum sp. nov., a magnesium-dependent haloarchaeon isolated from commercial salt.

Two extremely halophilic archaea, strains MGY-184(T) and MGY-205, were isolated from sea salt produced in Japan and rock salt imported from Bolivia, respectively. Both strains were pleomorphic, non-motile, Gram-negative and required more than 5 % (w/v) NaCl for growth, with optimum at 9-12 %, in the presence of 2 % (w/v) MgCl2 . 6H2O. In the presence of 18 % (w/v) MgCl2 . 6H2O, however, both strains showed growth even at 1.0 % (w/v) NaCl. Both strains possessed two 16S rRNA genes (rrnA and rrnB), and they revealed closest similarity to Halobaculum gomorrense JCM 9908(T), the single species with a validly published name of the genus Halobaculum, with similarity of 97.8 %. The rrnA and rrnB genes of both strains were 100 % similar. The rrnA genes were 97.6 % similar to the rrnB genes in both strains. DNA G+C contents of strains MGY-184(T) and MGY-205 were 67.0 and 67.4 mol%, respectively. Polar lipid analysis revealed that the two strains contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester derived from C20C20 archaeol. The DNA-DNA hybridization value between the two strains was 70 % and both strains showed low levels of DNA-DNA relatedness (48-50 %) with Halobaculum gomorrense JCM 9908(T). Physiological and biochemical characteristics allowed differentiation of strains MGY-184(T) and MGY-205 from Halobaculum gomorrense JCM 9908(T). Therefore, strains MGY-184(T) and MGY-205 represent a novel species of the genus Halobaculum, for which the name Halobaculum magnesiiphilum sp. nov. is proposed; the type strain is MGY-184(T) ( = JCM 17821(T) = KCTC 4100(T)).

Diffraction contrast analysis of 90° and 180° ferroelectric domain structures of PbTiO3 thin films.

The ferroelectric domain structure of a PbTiO3 thin film on (100) SrTiO3 has been investigated by transmission electron microscopy (TEM). Two types of a-domain were found: one extended through the film to the surface and another comprised small a-domains confined within the film. Dark-field TEM (DFTEM) observation revealed that 180° domains formed near the substrate and stopped their growth 100 nm away from the substrate. The DFTEM observation also revealed that 90° domain boundaries had head-to-tail structures. To confirm the polarization direction obtained by experiments, diffracted intensities under a two-beam condition were simulated using the extended Darwin-Howie-Whelan equations. On the basis of the obtained results, a ferroelectric domain structure model of PbTiO3 thin films on SrTiO3 is proposed.

Configuration and local elastic interaction of ferroelectric domains and misfit dislocation in PbTiO3/SrTiO3 epitaxial thin films.

We have studied the strain field around the 90° domains and misfit dislocations in PbTiO3/SrTiO3 (001) epitaxial thin films, at the nanoscale, using the geometric phase analysis (GPA) combined with high-resolution transmission electron microscopy (HRTEM) and high-angle annular dark field--scanning transmission electron microscopy (HAADF-STEM). The films typically contain a combination of a/c-mixed domains and misfit dislocations. The PbTiO3 layer was composed from the two types of the a-domain (90° domain): a typical a/c-mixed domain configuration where a-domains are 20-30 nm wide and nano sized domains with a width of about 3 nm. In the latter case, the nano sized a-domain does not contact the film/substrate interface; it remains far from the interface and stems from the misfit dislocation. Strain maps obtained from the GPA of HRTEM images show the elastic interaction between the a-domain and the dislocations. The normal strain field and lattice rotation match each other between them. Strain maps reveal that the a-domain nucleation takes place at the misfit dislocation. The lattice rotation around the misfit dislocation triggers the nucleation of the a-domain; the normal strains around the misfit dislocation relax the residual strain in a-domain; then, the a-domain growth takes place, accompanying the introduction of the additional dislocation perpendicular to the misfit dislocation and the dissociation of the dislocations into two pairs of partial dislocations with an APB, which is the bottom boundary of the a-domain. The novel mechanism of the nucleation and growth of 90° domain in PbTiO3/SrTiO3 epitaxial system has been proposed based on above the results.

Comparison of BST film microwave tunable devices based on (100) and (111) MgO substrates.

We have increased the figure-of-merit (FOM) of a (Ba,Sr)TiO3 (BST) film microwave tunable device by approximately three times for MgO(111) compared with a MgO(100) substrate at a frequency range of 20 GHz. Differences in permittivity and tunability in a BST film may be closely related to the difference in the film strain. The ratio of calculated permittivities of BST(100) and BST(111) films nearly corresponds to that of the FOM in the microwave range, which was rather unexpected because a higher permittivity leads to both larger tunability and dielectric loss in ferroelectrics. From a series of results, it is suggested that there are additional influences of orientation (other than the direct influence of strain itself) on the tunable properties in BST films especially in the high-frequency region.

Tunable thin film bulk acoustic wave resonator based on Ba(x)Sr(1-x)TiO3 thin film.

A tunable membrane-type thin film bulk acoustic wave resonator (TFBAR) based on a Ba(0.3)Sr(0.7)TiO(3)(BST) thin film has been fabricated. The resonance and antiresonance frequencies of the device can be altered by applying a dc bias: both shift down with increasing dc electric field. The resonance and antiresonance frequencies showed a tuning of -2.4% and -0.6%, respectively, at a maximum dc electric field of 615 kV/cm. The electromechanical coupling factor of the device increased up to 4.4%. We demonstrate that the tuning of the TFBAR is nonhysteretic. The Q-factor of the device showed some variation with dc bias and is about 200. The tuning of the TFBAR is caused by the dc bias dependence of the sound velocity and the intrinsic electromechanical coupling factor of the BST layer. We apply our recently developed theory on the electrical tuning of dc bias induced acoustic resonances in paraelectric thin films to successfully model the tuning behavior of the TFBAR. The modeling enabled us to de-embed the intrinsic electromechanical properties of the BST thin film. We show that the mechanical load of our device does not significantly degrade the tuning performance of the BST layer. The performance of the TFBAR is compared with the available data on varactor tuned TFBARs.

Case report of extragingival peripheral ameloblastoma in buccal mucosa.

A peripheral ameloblastoma (PA) is a rare variant of ameloblastoma that generally occurs in the extraosseous region; an extragingival PA is extremely rare. There have been 5 cases reported of a PA occurring in the buccal mucosa and 1 in the oral floor. We present the sixth known case of extragingival PA in the buccal mucosa, which occurred in an 88-year-old woman.

Weak interplate coupling by seamounts and repeating M approximately 7 earthquakes.

Subducting seamounts are thought to increase the normal stress between subducting and overriding plates. However, recent seismic surveys and laboratory experiments suggest that interplate coupling is weak. A seismic survey in the Japan Trench shows that a large seamount is being subducted near a region of repeating earthquakes of magnitude M approximately 7. Both observed seismicity and the pattern of rupture propagation during the 1982 M 7.0 event imply that interplate coupling was weak over the seamount. A large rupture area with small slip occurred in front of the seamount. Its northern bound could be determined by a trace of multiple subducted seamounts. Whereas a subducted seamount itself may not define the rupture area, its width may be influenced by that of the seamount.

Regulated growth of diatom cells on self-assembled monolayers.

We succeeded in regulating the growth of diatom cells on chemically modified glass surfaces. Glass surfaces were functionalized with -CF3, -CH3, -COOH, and -NH2 groups using the technique of self-assembled monolayers (SAM), and diatom cells were subsequently cultured on these surfaces. When the samples were rinsed after the adhesion of the diatom cells on the modified surfaces, the diatoms formed two dimensional arrays; this was not possible without the rinsing treatment. Furthermore, we examined the number of cells that grew and their motility by time-lapse imaging in order to clarify the interaction between the cells and SAMs. We hope that our results will be a basis for developing biodevices using living photosynthetic diatom cells.

DC bias-dependent shift of the resonance frequencies in BST thin film membranes.

Direct current (DC) bias-dependent acoustic resonance phenomena have been observed in micromachined tunable thin film capacitors based on Ba(0.3)Sr(0.7)TiO3 (BST) thin films. The antiresonance frequency is only weakly DC bias dependent, and the resonance frequency exhibits a much stronger dependence on the applied DC bias. The resonance frequency shifted by 1.2% for a frequency of about 6.7 GHz and an applied field of 667 KV/cm. At the same time the effective electromechanical coupling constant k(2)(t,eff) increased to 2.0%. The tuning of the resonance frequency depends on the tunability of the film permittivity and on the mechanical load on the piezoactive layer. The experimental observations correlate well with the theoretical predictions derived from the free energy P expansion using Landau theory.

Human placenta feeder layers support undifferentiated growth of primate embryonic stem cells.

Various undifferentiated embryonic stem (ES) cells can grow on mouse embryonic fibroblast (MEF) feeders. However, the risk of zoonosis from animal feeders to human ES cells generally excludes the clinical use of these human ES cells. We have found that human placenta is a useful source of feeder cells for the undifferentiated growth of primate ES cells. As on MEF feeders, primate ES cells cultured on human amniotic epithelial (HAE) feeder cells and human chorionic plate (HCP) cells had undifferentiated growth. The cultured primate ES cells expressed Oct-4, alkaline phosphatase, and SSEA-4. The primate ES cells on HAE feeder cells produced typical immature teratomas in vivo after injection into severe combined immunodeficient mice. Human placenta is quite novel and important because it would provide a relatively available source of feeders for the growth of human ES cells for therapeutic purposes that are also free of ethical complications.