Origin of the high piezoelectric response in PbZr(1-x)TixO3

High resolution x-ray powder diffraction measurements on poled PbZr(1-x)TixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary, MPB) have shown that for both rhombohedral and tetragonal compositions, the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion. This work provides the first direct evidence for the origin of the very high piezoelectricity in PZT.Comment: 4 pages, 4 EPS figures embedded. More specific title and abstract. To appear in Phys. Rev. Let

Eigenmode Tomography of Surface Charge Oscillations of Plasmonic Nanoparticles by Electron Energy Loss Spectroscopy

Plasmonic devices designed in three dimensions enable careful tuning of optical responses for control of complex electromagnetic interactions on the nanoscale. Probing the fundamental characteristics of the constituent nanoparticle building blocks is, however, often constrained by diffraction-limited spatial resolution in optical spectroscopy. Electron microscopy techniques, including electron energy loss spectroscopy (EELS), have recently been developed to image surface plasmon resonances qualitatively at the nanoscale in three dimensions using tomographic reconstruction techniques. Here, we present an experimental realization of a distinct method that uses direct analysis of modal surface charge distributions to reconstruct quantitatively the three-dimensional eigenmodes of a silver right bipyramid on a metal oxide substrate. This eigenmode tomography removes ambiguity in two-dimensional imaging of spatially-localized plasmonic resonances, reveals substrate-induced mode degeneracy breaking in the bipyramid, and enables EELS for the analysis not of a particular electron-induced response but of the underlying geometric modes characteristic of particle surface plasmons.S.M.C. acknowledges support of a Gates Cambridge Scholarship. E.R. acknowledges support from the Royal Society's Newton International Fellowship scheme and a Trinity Hall Research Fellowship. We thank Ben Knappet for assistance with the synthesis of the silver bipyramids. We thank F.J. de la Peña for helpful discussions on the use of HYPERSPY. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (No. FP7/2007-2013)/ERC Grant Agreement No. 291522-3DIMAGE and the European Union's Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483-ESTEEM2)This is the final version of the article. It was first available from ACS via http://dx.doi.org/10.1021/acsphotonics.5b0042

Adsorption of chromium VI from aqueous solutions onto nanoparticle sorbent: Chitozan-Fe-Zr

Background and purpose: Various contaminants are released into water resources each year as a results of urbanization and industrialization. Chromium VI is one of the most toxic metals released into the aquatic environments, wastewater, and soil mainly via industrial sewage. The purpose of this study was to evaluate the performance of iron-zirconium/chitosan magnetic nanoparticles composite in removal of hexavalent chromium VI from aquatic environments. Materials and methods: A pilot-study was conducted in laboratory scale. Nancomposites synthesis was done using chemical precipitation and tested by SEM, XRD, and FTIR. Various factors such as contact time (0-720 min), initial pH of the solution (2-12), adsorbent dose (0.4-2 gr), initial concentration of metal (0-10 milligrams per liter), and the system temperature (15-35 �) were studied. The concentration of heavy metal chromium was measured using a spectrophotometer at 540nm. Results: The results showed that the highest removal efficiency of heavy metal chromium was obtained at pH 4.0 (52.99). Moreover, addition of 1 gr composite in the same concentration could boost removing the hexavalent chromium by more than 91. Increasing the concentration levels of heavy metals had little impact on the removal efficiency. Adsorption isotherms fitted the Freundlich isotherm. Conclusion: According to the results, the absorbent showed a high performance in removing chromium VI from aquatic environments. © 2016, Mazandaran University of Medical Sciences. All rights reserved

Heterovalent and A-atom effects in A(B'B'')O3 perovskite alloys

Using first-principles supercell calculations, we have investigated energetic, structural and dielectric properties of three different A(B'B'')O_3 perovskite alloys: Ba(Zn_{1/3}Nb_{2/3})O_3 (BZN), Pb(Zn_{1/3}Nb_{2/3})O_3 (PZN), and Pb(Zr_{1/3}Ti_{2/3})O_3 (PZT). In the homovalent alloy PZT, the energetics are found to be mainly driven by atomic relaxations. In the heterovalent alloys BZN and PZN, however, electrostatic interactions among B' and B'' atoms are found to be very important. These electrostatic interactions are responsible for the stabilization of the observed compositional long-range order in BZN. On the other hand, cell relaxations and the formation of short Pb--O bonds could lead to a destabilization of the same ordered structure in PZN. Finally, comparing the dielectric properties of homovalent and heterovalent alloys, the most dramatic difference arises in connection with the effective charges of the B' atom. We find that the effective charge of Zr in PZT is anomalous, while in BZN and PZN the effective charge of Zn is close to its nominal ionic value.Comment: 7 pages, two-column style with 2 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/index.html#lb_he

Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a postannealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensorPeer reviewe

Prostacyclin Promotes Degenerative Pathology in a Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is the most common form of dementia in aged populations. A substantial amount of data demonstrates that chronic neuroinflammation can accelerate neurodegenerative pathologies. In AD, chronic neuroinflammation results in the upregulation of cyclooxygenase and increased production of prostaglandin H2, a precursor for many vasoactive prostanoids. While it is well-established that many prostaglandins can modulate the progression of neurodegenerative disorders, the role of prostacyclin (PGI2) in the brain is poorly understood. We have conducted studies to assess the effect of elevated prostacyclin biosynthesis in a mouse model of AD. Upregulated prostacyclin expression significantly worsened multiple measures associated with amyloid-β (Aβ) disease pathologies. Mice overexpressing both Aβ and PGI2 exhibited impaired learning and memory and increased anxiety-like behavior compared with non-transgenic and PGI2 control mice. PGI2 overexpression accelerated the development of Aβ accumulation in the brain and selectively increased the production of soluble Aβ42. PGI2 damaged the microvasculature through alterations in vascular length and branching; Aβ expression exacerbated these effects. Our findings demonstrate that chronic prostacyclin expression plays a novel and unexpected role that hastens the development of the AD phenotype

Nanomagnetic properties of the meteorite cloudy zone.

Meteorites contain a record of their thermal and magnetic history, written in the intergrowths of iron-rich and nickel-rich phases that formed during slow cooling. Of intense interest from a magnetic perspective is the "cloudy zone," a nanoscale intergrowth containing tetrataenite-a naturally occurring hard ferromagnetic mineral that has potential applications as a sustainable alternative to rare-earth permanent magnets. Here we use a combination of high-resolution electron diffraction, electron tomography, atom probe tomography (APT), and micromagnetic simulations to reveal the 3D architecture of the cloudy zone with subnanometer spatial resolution and model the mechanism of remanence acquisition during slow cooling on the meteorite parent body. Isolated islands of tetrataenite are embedded in a matrix of an ordered superstructure. The islands are arranged in clusters of three crystallographic variants, which control how magnetic information is encoded into the nanostructure. The cloudy zone acquires paleomagnetic remanence via a sequence of magnetic domain state transformations (vortex to two domain to single domain), driven by Fe-Ni ordering at 320 °C. Rather than remanence being recorded at different times at different positions throughout the cloudy zone, each subregion of the cloudy zone records a coherent snapshot of the magnetic field that was present at 320 °C. Only the coarse and intermediate regions of the cloudy zone are found to be suitable for paleomagnetic applications. The fine regions, on the other hand, have properties similar to those of rare-earth permanent magnets, providing potential routes to synthetic tetrataenite-based magnetic materials.European Research Counci

Aging-like Phenotype and Defective Lineage Specification in SIRT1-Deleted Hematopoietic Stem and Progenitor Cells

Summary Aging hematopoietic stem cells (HSCs) exhibit defective lineage specification that is thought to be central to increased incidence of myeloid malignancies and compromised immune competence in the elderly. Mechanisms underlying these age-related defects remain largely unknown. We show that the deacetylase Sirtuin (SIRT)1 is required for homeostatic HSC maintenance. Differentiation of young SIRT1-deleted HSCs is skewed toward myeloid lineage associated with a significant decline in the lymphoid compartment, anemia, and altered expression of associated genes. Combined with HSC accumulation of damaged DNA and expression patterns of age-linked molecules, these have striking overlaps with aged HSCs. We further show that SIRT1 controls HSC homeostasis via the longevity transcription factor FOXO3. These findings suggest that SIRT1 is essential for HSC homeostasis and lineage specification. They also indicate that SIRT1 might contribute to delaying HSC aging

Estimation of Inbreeding Coefficients Using Pedigree and Microsatellite Markers and Its Effects on Economic Traits of Shirvan Kordi Sheep

INTRODUCTION Intensive selection within a single population of finite size reduces the genetic variability and increases the rate of inbreeding KEY WORDS Research Article Estimation of Inbreeding Coefficients in Shirvan Kordi Sheep In the overdominance hypothesis, inbreeding depression is attributable to higher fitness of heterozygotes for the loci in question. For the partial recessive hypothesis, negative fitness consequences are due to the fixation of recessive or partially recessive deleterious alleles Microsatellites has been widely used as reliable molecular markers to study the genetic relationship of different populations and for indirect measures of inbreeding. They are codominant, highly polymorphic, highly abundant, heritable, locus specific, and easily analyzed and therefore suitable for studies on population phylogenesis constitution This study was carried out using microsatellite markers because they are powerful tools for tracking alleles through a population and to estimate genetic variability and inbreeding Marker data collected provides information on population structure, relatedness and inbreeding MATERIALS AND METHODS Data Pedigree information from 1989 to 2009 of a flock of Kordi sheep maintained at Shirvan Sheep Breeding Station was used. Pedigree file contained information on individual identification number, sex, type of birth, dam and sire as well as birth date and included 7170 registered animals (3332 males and 3838 females), progeny of177 sires and 2182 dams. Pedigree analysis Inbreeding coefficients of the animals were computed using the CFC program Microsatellite method Blood samples (5 mL) of 100 animals were collected from the jugular vein and transferred into vacutainer tubes containing 0.5 molar EDTA as anticoagulant and frozen at -20 ˚C. Total DNA was isolated from blood samples using the Diatom DNA Kit, according to the manufacturer instructions. The quantity and quality of the isolated DNA was determined using both spectrophotometry and by 0.8% agarose gel electrophoresis. Characteristics of the microsatellite markers used in this study are listed in Approximately, 100 ng DNA (adjusted concentration) was used as template for polymerase chain reaction (PCR). The PCR reaction cycle was carried out in a the rmocycler (Biorad) by denaturation at 95 ˚C for 4 min, denaturation at 95 ˚C for 45 sec, primer annealing for 45 sec at the desired temperature (55-60 ˚C) and an extension for 1 min at 72 ˚C, repeating the cycle 35 times. The final extension step was at 72 ˚C for 4 min. The PCR amplification was conducted in a 12 μL volume. PCR products were analyzed by vertical electrophoresis in 6% non-denaturing polyacrylamide gel (170 V, 3-4 h) and bands visualized by rapid silver staining Molecular data analysis Molecular data were analysed using the POPGENE V1.32 RESULTS AND DISCUSSION Pedigree analysis The analysis of pedigree revealed that mean level of inbreeding (F) of all animals acrossall years (1989-2009) was 0.668%. Moreover, the minimum and maximum coefficientsof inbreeding for the animals in the flock was 0 and 31.25%, respectively. The low average coefficient of inbreeding could be ascribed to breeding strategies at the station for preventing mating of relatives. Totally, 23.26% of the animals (1668 out of 7170) were inbred with a mean inbreeding coefficient of 2.87%. In the pedigree, 3332 and 3838 of the animals were males and females with mean inbreeding coefficients of 0.693% and 0.646%, respectively. Out of all, 1668 animals were inbred. These included 823 males and 845 females having average inbreeding coefficient of 2.81% and 2.93%, respectively. These results indicated that fewmatings of close relatives have occurred. Descriptive statistics for inbreeding coefficients for the entire population and the inbred portion of the population are shown in 135 Estimation of Inbreeding Coefficients in Shirvan Kordi Sheep Mean of all traits decreased and increased irregularly by increasing inbreeding coefficients. This could be due to fewer records in the numerically higher classes of inbreeding. Inbreeding depression Details of the data used for the estimation of inbreeding depression are given in Regression coefficients and their standard errors on inbreeding coefficients were -0.0013 ± 0.0003 kg for BWT, 0.080 ± 0.015 kg for WWT, 0.001 ± 0.0009 kg for BW6M, -0.065 ± 0.055 kg for BW9M, -0.092 ± 0.063 kg for BW12M, 0.008 ± 0.0066kg for Wool and -0.023 ± 0.012 lambs for LS. Pre-weaning growth traits BWT: birth weight trait; WWT: weaning weight trait; BW6M: body weight at 6 months of age trait; BW9W: body weight at 9 months of age trait; BW12M: body weight at 12 months of age trait; Wool: wool produced annually and LS: number of lambs per ewe lambing. Changes for every one percent increase in inbreeding coefficient for BWT and WWT were -0.0131 and 0.0795 kg, respectively. Regression coefficient estimate for BWT Regression coefficients for BW in the 9 th and 12 th month were more than all the other studied traits. Estimates of -0.0653 and -0.0921 kg per 1% increase in inbreeding coefficient for BW in 9 th month and BW in 12 th month, were more than the values reported in other studies. Annual wool production and number of lambs per ewe lambing The effect of inbreeding on wool produced annually and the number of lambs per ewe lambing amounted to 0.0083 kg and -0.023 lambs, respectively. For the annual wool production, the linear effect of individual inbreeding, regression was positive but non-significant. On the average, an increase in 1 percent in individual inbreeding increased the wool produced annually by 0.0083 kg. A review b

Conformal TiO2_2 aerogel-like films by plasma deposition: from omniphobic antireflective coatings to perovskite solar cells photoelectrodes

The ability to control porosity in oxide thin films is one of the key factors that determine their properties. Despite the abundance of dry processes for the synthesis of oxide porous layers, the high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultra-porous titanium dioxide thin films at room or mild temperatures (T lower or equal to 120 degrees Celsius) by the sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85 percent that are comparable to advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures presenting a distribution of anatase clusters embedded in the sponge-like structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees Celsius in air, which increases the fraction of the embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive becoming super-hydrophilic subjected to UV light irradiation The supported percolated nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel film thickness reaching efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and is applicable to ultra-high porous conformal oxides of different compositions with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.Comment: 31 pages, 10 Figs. plus Supporting Information 7 pags, 6 figs. Full Pape