Reversible change in electrical and optical properties in epitaxially grown Al-doped ZnO thin films

Aluminum-doped ZnO (AZO) films were epitaxially grown on sapphire (0001) substrates using pulsed laser deposition. As-deposited AZO films had a low resistivity of 8.01× 10-4 Ω cm. However, after annealing at 450 °C in air, the electrical resistivity of the AZO films increased to 1.97× 10-1 Ω cm because of a decrease in the carrier concentration. Subsequent annealing of the air-annealed AZO films in H2 recovered the electrical conductivity of the AZO films. In addition, the conductivity change was reversible upon repeated air and H2 annealing. A photoluminescence study showed that oxygen interstitial (Oi′) is a critical material parameter allowing for the reversible control of the electrical conducting properties of AZO films. © 2008 American Institute of Physics

Seed-layer mediated orientation evolution in dielectric Bi-Zn-Ti-Nb-O thin films

Highly (hhh) -oriented pyrochlore Bi-Zn-Ti-Nb-O (BZTN) thin films were fabricated via metal-organic decomposition using orientation template layers. The preferred orientation was ascribed to the interfacial layer, the lattice parameter of which is similar to BZTN. High-resolution transmission electron microscopy supported that the interfacial layer consists of Bi and Pt. The (hhh) -oriented thin films exhibited a highly insulating nature enabling feasible applications in electronic devices, particularly voltage tunable application. The BZTN thin films did not show any apparent dielectric anisotropy and the slightly enhanced dielectric properties were discussed in connection to the internal stress and the grain boundary effect. © 2007 American Institute of Physics

Structure and dielectric properties of cubic Bi<inf>2</inf>(Zn <inf>1/3</inf>Ta<inf>2/3</inf>)<inf>2</inf> O<inf>7</inf> thin films

Pyrochlore Bi2(Zn1/3Ta2/3)2 O7 (BZT) films were prepared by pulsed laser deposition on Pt/TiO2/SiO2/Si substrates. In contrast to bulk monoclinic BZT ceramics, the BZT films have a cubic structure mediated by an interfacial layer. The dielectric properties of the cubic BZT films [ε∼177, temperature coefficient of capacitance (TCC) ∼-170 ppm/°C] are much different from those of monoclinic BZT ceramics (ε∼61, TCC ∼+60 ppm/°C). Increasing the thickness of the BZT films returns the crystal structure to the monoclinic phase, which allows the dielectric properties of the BZT films to be tuned without changing their chemical composition. © 2009 American Institute of Physics

Association Between Proton Pump Inhibitor Use During Early Pregnancy and Risk of Congenital Malformations

Importance: Proton pump inhibitors (PPIs) are increasingly used during pregnancy; however, several observational studies have raised concerns about an increased risk of specific types of congenital malformations. Objective: To examine the association between PPI exposure during early pregnancy and the risk of congenital malformations. Design, Setting, and Participants: This population-based cohort study used data from the National Health Insurance Service-National Health Information Database of South Korea (2010-2020); sibling-controlled analyses were conducted to account for familial factors. A total of 2 696 216 pregnancies in women aged 19 to 44 years between June 1, 2011, and December 31, 2019, and their live-born infants were identified. Pregnant women who were exposed to known teratogens or who delivered infants with chromosomal abnormalities or genetic syndromes were excluded. Data on participant race and ethnicity were not collected because the National Health Information Database does not report this information. Exposures: Proton pump inhibitor use during the first trimester. Main Outcomes and Measures: Primary outcomes were major congenital malformations, congenital heart defects, cleft palate, hydrocephalus, and hypospadias. The subtypes of major congenital malformations and congenital heart defects were evaluated as exploratory outcomes. Propensity score fine stratification was used to control for potential confounders, and a weighted generalized linear model was used to estimate relative risks with 95% CIs. Results: Of 2 696 216 pregnancies (mean [SD] maternal age, 32.1 [4.2] years), 40 540 (1.5%; mean [SD] age, 32.4 [4.6] years) were exposed to PPIs during the first trimester. The absolute risk of major congenital malformations was 396.7 per 10 000 infants in PPI-exposed pregnancies and 323.4 per 10 000 infants in unexposed pregnancies. The propensity score-adjusted relative risks were 1.07 (95% CI, 1.02-1.13) for major congenital malformations, 1.09 (95% CI, 1.01-1.17) for congenital heart defects, 1.02 (95% CI, 0.72-1.43) for cleft palate, 0.94 (95% CI, 0.54-1.63) for hydrocephalus, and 0.77 (95% CI, 0.51-1.17) for hypospadias. In the sibling-controlled analyses, no associations were observed between PPI use and primary outcomes, including major congenital malformations (odds ratio, 1.05; 95% CI, 0.91-1.22) and congenital heart defects (odds ratio, 1.07; 95% CI, 0.88-1.30). A range of sensitivity analyses revealed results that were similar to the main findings. Conclusions and Relevance: In this cohort study, the use of PPIs during early pregnancy was not associated with a substantial increase in the risk of congenital malformations, although small increased risks were observed for major congenital malformations and congenital heart defects; findings from sibling-controlled analyses revealed that PPIs were unlikely to be major teratogens. These findings may help guide clinicians and patients in decision-making about PPI use in the first trimester

Boiling on spatially controlled heterogeneous surfaces: Wettability patterns on microstructures

We investigated nucleate boiling heat transfer with precisely controlled wetting patterns and micro-posts, to gain insights into the impact of surface heterogeneity. To create heterogeneous wetting patterns, self-assembled monolayers (SAMs) were spatially patterned. Even at a contact angle <90°, bubble nucleation and bubble frequency were accelerated on SAM patterns, since this contact angle is larger than that found on plain surfaces. Micro-posts were also fabricated on the surface, which interrupted the expansion of generated bubbles. This surface structuring induced smaller bubbles and higher bubble frequency than the plain surface. The resistance provided by surface structures to bubble expansion broke the interface between the vapor mushroom and the heating surface, and water could therefore be continuously supplied through these spaces at high heat flux. To induce synergistic effects with wetting patterns and surface structures on boiling, we fabricated SAM patterns onto the heads of micro-posts. On this combined surface, bubble nucleation was induced from the head of the micro-posts, and bubble growth was influenced by both the SAM pattern and the micro-post structures. In particular, separation of the vapor path on the SAM patterns and the liquid path between micro-post structures resulted in high heat transfer performance without critical heat flux deterioration. © 2015 AIP Publishing LLC.open112023Nsciescopu

Direct Observation of Localized Spin Antiferromagnetic Transition in PdCrO2 by Angle-Resolved Photoemission Spectroscopy

We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin ordering pattern of Cr3+ ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements, and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system.X1118sciescopu

Directed self-assembly of a helical nanofilament liquid crystal phase for use as structural color reflectors

The fabrication of molecular structures with a desired morphology, e.g., nanotubes, nanoribbons, nanosprings, and sponges, is essential for the advancement of nanotechnology. Unfortunately, realization of this objective is expensive and complicated. Here, we report that irradiating a film comprising azobenzene derivatives with UV light produces oriented arrays of helical nanofilaments via the photoisomerization-induced Weigert effect. As a result, structural colors are observed due to the extrinsic chiral reflection in the visible wavelength range, and the reflected color can be tuned by adjusting the molecular length of the azobenzene derivative. This simple fabrication method can be used for fabricating large, reversible, and patternable color reflectors, providing a new platform for interference-based structural coloration as it exists in nature, such as morpho butterflies, green-winged teal, and various beetles

Measurement of CP-violation asymmetries in D0 to Ks pi+ pi-

We report a measurement of time-integrated CP-violation asymmetries in the resonant substructure of the three-body decay D0 to Ks pi+ pi- using CDF II data corresponding to 6.0 invfb of integrated luminosity from Tevatron ppbar collisions at sqrt(s) = 1.96 TeV. The charm mesons used in this analysis come from D*+(2010) to D0 pi+ and D*-(2010) to D0bar pi-, where the production flavor of the charm meson is determined by the charge of the accompanying pion. We apply a Dalitz-amplitude analysis for the description of the dynamic decay structure and use two complementary approaches, namely a full Dalitz-plot fit employing the isobar model for the contributing resonances and a model-independent bin-by-bin comparison of the D0 and D0bar Dalitz plots. We find no CP-violation effects and measure an asymmetry of ACP = (-0.05 +- 0.57 (stat) +- 0.54 (syst))% for the overall integrated CP-violation asymmetry, consistent with the standard model prediction.Comment: 15 page

CXCR6, a Newly Defined Biomarker of Tissue-Specific Stem Cell Asymmetric Self-Renewal, Identifies More Aggressive Human Melanoma Cancer Stem Cells

Background: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs) from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+. Conclusions/Significance: The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment