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Sample records for high-dielectric-strength antiferroelectric afe

  1. Method of bistable optical information storage using antiferroelectric phase PLZT ceramics

    Science.gov (United States)

    Land, Cecil E.

    1990-01-01

    A method for bistable storage of binary optical information includes an antiferroelectric (AFE) lead lanthanum zirconate titanate (PLZT) layer having a stable antiferroelectric first phase and a ferroelectric (FE) second phase obtained by applying a switching electric field across the surface of the device. Optical information is stored by illuminating selected portions of the layer to photoactivate an FE to AFE transition in those portions. Erasure of the stored information is obtained by reapplying the switching field.

  2. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    Directory of Open Access Journals (Sweden)

    Aditya Chauhan

    2015-11-01

    Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

  3. Switching and energy-storage characteristics in PLZT 2/95/5 antiferroelectric ceramic system

    Directory of Open Access Journals (Sweden)

    A. Peláiz-Barranco

    2016-12-01

    Full Text Available Switching mechanisms and energy-storage properties have been investigated in (Pb0.98La0.02(Zr0.95Ti0.050.995O3 antiferroelectric ceramics. The electric field dependence of polarization (P–E hysteresis loops indicates that both the ferroelectric (FE and antiferroelectric (AFE phases coexist, being the AFE more stable above 100∘C. It has been observed that the temperature has an important influence on the switching parameters. On the other hand, the energy-storage density, which has been calculated from the P–E hysteresis loops, shows values higher than 1J/cm3 for temperatures above 100∘C with around 73% of efficiency as average. These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application.

  4. Antiferroelectric polarization switching and dynamic scaling of energy storage: A Monte Carlo simulation

    Science.gov (United States)

    Huang, B. Y.; Lu, Z. X.; Zhang, Y.; Xie, Y. L.; Zeng, M.; Yan, Z. B.; Liu, J.-M.

    2016-05-01

    The polarization-electric field hysteresis loops and the dynamics of polarization switching in a two-dimensional antiferroelectric (AFE) lattice submitted to a time-oscillating electric field E(t) of frequency f and amplitude E0, is investigated using Monte Carlo simulation based on the Landau-Devonshire phenomenological theory on antiferroelectrics. It is revealed that the AFE double-loop hysteresis area A, i.e., the energy loss in one cycle of polarization switching, exhibits the single-peak frequency dispersion A(f), suggesting the unique characteristic time for polarization switching, which is independent of E0 as long as E0 is larger than the quasi-static coercive field for the antiferroelectric-ferroelectric transitions. However, the dependence of recoverable stored energy W on amplitude E0 seems to be complicated depending on temperature T and frequency f. A dynamic scaling behavior of the energy loss dispersion A(f) over a wide range of E0 is obtained, confirming the unique characteristic time for polarization switching of an AFE lattice. The present simulation may shed light on the dynamics of energy storage and release in AFE thin films.

  5. Pressure-induced ferroelectric to antiferroelectric phase transformation in porous PZT95/5 ceramics

    International Nuclear Information System (INIS)

    Zeng, T.; Dong, X.L.; Chen, X.F.; Yao, C.H.; He, H.L.

    2007-01-01

    The hydrostatic pressure-induced ferroelectric to antiferroelectric (FE-AFE) phase transformation of PZT95/5 ceramics was investigated as a function of porosity, pore shape and pore size. FE-AFE phase transformations were more diffuse and occurred at lower hydrostatic pressures with increasing porosity. The porous PZT95/5 ceramics with spherical pores exhibited higher transformation pressures than those with irregular pores. Moreover, FE-AFE phase transformations of porous PZT95/5 ceramics with polydisperse irregular pores were more diffuse than those of porous PZT95/5 ceramics with monodisperse irregular pores. The relation between pore structure and hydrostatic pressure-induced FE-AFE transformation was established according to stress concentration theory. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Designing lead-free antiferroelectrics for energy storage

    Science.gov (United States)

    Xu, Bin; Íñiguez, Jorge; Bellaiche, L.

    2017-01-01

    Dielectric capacitors, although presenting faster charging/discharging rates and better stability compared with supercapacitors or batteries, are limited in applications due to their low energy density. Antiferroelectric (AFE) compounds, however, show great promise due to their atypical polarization-versus-electric field curves. Here we report our first-principles-based theoretical predictions that Bi1−xRxFeO3 systems (R being a lanthanide, Nd in this work) can potentially allow high energy densities (100–150 J cm−3) and efficiencies (80–88%) for electric fields that may be within the range of feasibility upon experimental advances (2–3 MV cm−1). In addition, a simple model is derived to describe the energy density and efficiency of a general AFE material, providing a framework to assess the effect on the storage properties of variations in doping, electric field magnitude and direction, epitaxial strain, temperature and so on, which can facilitate future search of AFE materials for energy storage. PMID:28555655

  7. Dicty_cDB: AFE812 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available AGTAATTTAAAAAAAAAAAAACCA AAAAAAAAAXXXXXXXXXXCCANATTTCCATANATGTGTTNAAANACGTGGNGGNA.... ID AFE812Z 3' end seq. >AFE812Z.Seq ----------CCANATTTCCATANATGTGTTNAAANACGTGGNGGNATCTTAAGNTGNGA ATTTNATCC...ATACAATTAAAAAAAGTTA AAATTAAATTTGTAAAATCAATTTGTAACAAAAACTAGTAATTTAAAAAAAAAAAAACCA AAAAAAAAA----------CCANATTTCCATANA

  8. Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading

    Science.gov (United States)

    Zhang, Jingyi

    Ferroelectric (FE) and closely related antiferroelectric (AFE) materials have unique electromechanical properties that promote various applications in the area of capacitors, sensors, generators (FE) and high density energy storage (AFE). These smart materials with extensive applications have drawn wide interest in the industrial and scientific world because of their reliability and tunable property. However, reliability issues changes its paradigms and requires guidance from detailed mechanism theory as the materials applications are pushed for better performance. A host of modeling work were dedicated to study the macro-structural behavior and microstructural evolution in FE and AFE material under various conditions. This thesis is focused on direct observation of domain evolution under multiphysics loading for both FE and AFE material. Landau-Devonshire time-dependent phase field models were built for both materials, and were simulated in finite element software Comsol. In FE model, dagger-shape 90 degree switched domain was observed at preexisting crack tip under pure mechanical loading. Polycrystal structure was tested under same condition, and blocking effect of the growth of dagger-shape switched domain from grain orientation difference and/or grain boundary was directly observed. AFE ceramic model was developed using two sublattice theory, this model was used to investigate the mechanism of energy efficiency increase with self-confined loading in experimental tests. Consistent results was found in simulation and careful investigation of calculation results gave confirmation that origin of energy density increase is from three aspects: self-confinement induced inner compression field as the cause of increase of critical field, fringe leak as the source of elevated saturation polarization and uneven defects distribution as the reason for critical field shifting and phase transition speed. Another important affecting aspect in polycrystalline materials is the

  9. Analogies between antiferromagnets and antiferroelectrics

    International Nuclear Information System (INIS)

    Enz, C.P.; Matthias, B.T.

    1980-01-01

    Ferro- and antiferromagnetism in the Laves phase TiBesub(2-x) Cusub(x) occurs for 0.1 4 H 2 PO 4 and its solid solutions with TlH 2 PO 4 and with the ferroelectric KH 2 PO 4 are discussed as function of deuteration and of pressure. Another analogy as function of pressure is established with the antiferroelectric perovskite PbZrO 3 . (author)

  10. Brillouin scattering, DSC, dielectric and X-ray diffraction studies of phase transitions in antiferroelectric PbHfO{sub 3}:Sn

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Kim, Tae Hyun [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Jankowska-Sumara, Irena [Institute of Physics, Pedagogical University, ul. Podchorążych 2, 30-084 Kraków (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Kojima, Seiji [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2015-02-15

    Highlights: • Phase transition mechanisms were studied in antiferroelectric PbHf{sub 0.975}Sn{sub 0.025}O{sub 3.} • Acoustic phonons showed anomalies at 472 and 426 K due to phase transitions. • Brillouin data showed evidence for presence of polar clusters in paraelectric phase. • An order-disorder mechanism of the PE to AFE2 transition was proved. - Abstract: Specific heat, dielectric, powder X-ray diffraction and Brillouin scattering studies of phase transitions in antiferroelectric PbHf{sub 0.975}Sn{sub 0.025}O{sub 3} crystal were performed. The specific heat data revealed clear anomalies at T{sub 1} = 473.5 and T{sub 2} = 426.3 K on cooling, which could be attributed to onset of first order phase transitions from the paraelectric (PE) phase to an intermediate antiferroelectric phase (AFE2) and the AFE2 phase to another antiferroelectric phase (AFE1), respectively. The estimated entropy changes at T{sub 1} and T{sub 2} pointed to mainly an order-disorder and displacive character of these transitions, respectively. X-ray diffraction data showed a complex superstructure of the intermediate phase with a = 11.895(6) Å, b = 11.936(4) Å, c = 8.223(3) Å at 453 K. Brillouin studies revealed pronounced softening of longitudinal acoustic (LA) mode in the PE phase associated with its broadening. The broadening and softening exhibited maximum values at T{sub 1}. Additional acoustic anomalies, that is, abrupt frequency shifts for LA and transverse acoustic (TA) modes were also observed at T{sub 2}. Brillouin scattering data also showed presence of a broad central peak (CP) that exhibited highest intensity at T{sub 1}. The observed temperature dependences of acoustic modes and CP indicate order-disorder character of the FE to AFE2 phase transition and importance of polar precursor clusters in the PE phase. The obtained data also suggest that the intermediate antiferroelectric phases in Sn{sup 4+} doped PbHfO{sub 3} and PbZrO{sub 3} may have very similar structures

  11. Domain configuration changes under electric field-induced antiferroelectric-ferroelectric phase transitions in NaNbO3-based ceramics

    International Nuclear Information System (INIS)

    Guo, Hanzheng; Randall, Clive A.; Shimizu, Hiroyuki; Mizuno, Youichi

    2015-01-01

    We recently developed a feasible crystal chemistry strategy to stabilize the antiferroelectricity in NaNbO 3 through a chemical substitution to decrease the tolerance factor and increase the average electronegativity of the system [Shimizu et al., Dalton Trans. 44, 10763 (2015) and Guo et al., J. Appl. Phys. 117, 214103 (2015)]. Two novel lead-free antiferroelectric (AFE) solid solutions, (1-x)NaNbO 3 -xCaZrO 3 and (1-x)NaNbO 3 -xSrZrO 3 , have been found to exhibit the double polarization hysteresis typical of a reversible AFE ↔ ferroelectric (FE) phase transition. In this study, as demonstrated by (1-x)NaNbO 3 -xCaZrO 3 system, the influence of chemical modification and electrical poling on the AFE/FE phase stability was investigated, primarily focusing on the microstructural and crystallographic evolutions. Together with the macroscopic polarization hysteresis measurements, a well-demonstrated structure-property relationship was presented. It was found that the CaZrO 3 substitution into NaNbO 3 can effectively destabilize the FE Q phase and correspondingly lead to a spontaneous reverting to AFE P phase. In contrast to the reversible AFE ↔ FE phase transition, the domain morphology evolution exhibits irreversible nature with a growing process of the orientational domains after applying electric field. Moreover, a multiple-zone axes electron diffraction map of P and Q phases has been summarized and is believed to be an efficient diagram to determine the AFE/FE nature of the NaNbO 3 -based systems

  12. Dicty_cDB: AFE742 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available AF (Link to library) AFE742 (Link to dictyBase) - - - - AFE742F (Link to Original s...ite) AFE742F 585 - - - - - - Show AFE742 Library AF (Link to library) Clone ID AFE742 (Link to dictyBase) Atlas ID - NBRP ID - dict...yBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/...Sequences producing significant alignments: (bits) Value N U36937 |U36937.1 Dictyostelium discoideum calreti...NA clone hj81f04, mRNA sequence. 36 3e-04 3 AY342298 |AY342298.1 Ictalurus puncta

  13. The antiferroelectric phase in KCN

    International Nuclear Information System (INIS)

    Santos, R.R. dos; Koiller, B.; Weid, J.P. von der; Ribeiro, S.C.; Chaves, A.S.; Barreto, F.C.S.

    1976-01-01

    The 83 K phase transition in KCN based on a simple model Hamiltonian, in which the interactions between the CN - ions are of an electrostatic dipole-dipole nature is studied. This leads to an antiferroelectric state in the ordered phase, as suggested previously by experiment. Still with this model Hamiltonian, but within a mean field approximation, is obtained an expression for the order parameter (sub-lattice polarization) of the transition as a function both of temperature and the electric dipole moment of the CN - ion. The available experimental value for the electric dipole moment of CN - in KCL (p=0.07 eA) yields a transition temperature Tc = 31.2 K. As this value of p is not reliable for the KCN crystal we have used the value that fits the experimental transition temperature (Tc 2 = 83 K) in order to obtain the order parameter as a function of temperature, as well as the orientational energy levels both for the disordered phase and for 0 K

  14. Dicty_cDB: AFE557 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available AF (Link to library) AFE557 (Link to dictyBase) - - - - AFE557F (Link to Original s...ite) AFE557F 540 - - - - - - Show AFE557 Library AF (Link to library) Clone ID AFE557 (Link to dictyBase) Atlas ID - NBRP ID - dict...yBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/...ificant alignments: (bits) Value N U36937 |U36937.1 Dictyostelium discoideum calr...|CB937139.1 IpCGJx13_12_E07_23 IpCGJx13 Ictalurus punctatus cDNA clone IpCGJx13_12_E07 5', mRNA sequence. 52

  15. Temperature-dependent dielectric and energy-storage properties of Pb(Zr,Sn,Ti)O{sub 3} antiferroelectric bulk ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xuefeng; Liu, Zhen; Xu, Chenhong; Cao, Fei; Wang, Genshui; Dong, Xianlin, E-mail: xldong@mail.sic.ac.cn [Key laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 200050, Shanghai (China)

    2016-05-15

    The dielectric and energy-storage properties of Pb{sub 0.99}Nb{sub 0.02}[(Zr{sub 0.60}Sn{sub 0.40}){sub 0.95}Ti{sub 0.05}]{sub 0.98}O{sub 3} (PNZST) bulk ceramics near the antiferroelectric (AFE)-ferroelectric (FE) phase boundary are investigated as a function of temperature. Three characteristic temperatures T{sub 0}, T{sub C}, T{sub 2} are obtained from the dielectric temperature spectrum. At different temperature regions (below T{sub 0}, between T{sub 0} and T{sub C}, and above T{sub C}), three types of hysteresis loops are observed as square double loop, slim loop and linear loop, respectively. The switching fields and recoverable energy density all first increase and then decrease with increasing temperature, and reach their peak values at ∼T{sub 0}. These results provide a convenient method to optimize the working temperature of antiferroelectric electronic devices through testing the temperature dependent dielectric properties of antiferroelectric ceramics.

  16. Ferroelectric-antiferroelectric mixed systems. Equation of state, thermodynamic functions

    Directory of Open Access Journals (Sweden)

    N.A.Korynevskii

    2006-01-01

    Full Text Available The problem of equation of state for ferroelectric-antiferroelectric mixed systems in the whole region of a concentration change (0≤n≤1 is discussed. The main peculiarity of the presented model turns out to be the possibility for the site dipole momentum to be oriented ferroelectrically in z-direction and antiferroelectrically in x-direction. Such a situation takes place in mixed compounds of KDP type. The different phases (ferro-, antiferro-, paraelectric, dipole glass and some combinations of them have been found and analyzed.

  17. Chiral HPLC and physical characterisation of orthoconic antiferroelectric liquid crystals

    Czech Academy of Sciences Publication Activity Database

    Vojtylová, Terézia; Żurowska, M.; Milewska, K.; Hamplová, Věra; Sýkora, D.

    2016-01-01

    Roč. 43, č. 9 (2016), s. 1244-1250 ISSN 0267-8292 R&D Projects: GA MŠk(CZ) LD14007; GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals * chiral HPLC * orthoconic antiferroelectric LC Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.661, year: 2016

  18. Effect of non-equilibrium flow chemistry and surface catalysis on surface heating to AFE

    Science.gov (United States)

    Stewart, David A.; Henline, William D.; Chen, Yih-Kanq

    1991-01-01

    The effect of nonequilibrium flow chemistry on the surface temperature distribution over the forebody heat shield on the Aeroassisted Flight Experiment (AFE) vehicle was investigated using a reacting boundary-layer code. Computations were performed by using boundary-layer-edge properties determined from global iterations between the boundary-layer code and flow field solutions from a viscous shock layer (VSL) and a full Navier-Stokes solution. Surface temperature distribution over the AFE heat shield was calculated for two flight conditions during a nominal AFE trajectory. This study indicates that the surface temperature distribution is sensitive to the nonequilibrium chemistry in the shock layer. Heating distributions over the AFE forebody calculated using nonequilibrium edge properties were similar to values calculated using the VSL program.

  19. Energy-storage properties and electrocaloric effect of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films.

    Science.gov (United States)

    Zhao, Ye; Hao, Xihong; Zhang, Qi

    2014-07-23

    Antiferroelectric (AFE) thick (1 μm) films of Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm(3) and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. A large reversible adiabatic temperature change of ΔT = 25.0 °C was presented in the thick films with x = 0.08 at 127 °C at 990 kV/cm. Moreover, all the samples had a lower leakage current density below 10(-6) A/cm(2) at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices.

  20. Electric response of Pb0.99[(Zr0.90Sn0.10)0.968Ti0.032]0.98Nb0.02O3 ceramics to the shock-wave-induced ferroelectric-to-antiferroelectric phase transition

    International Nuclear Information System (INIS)

    Jiang Dongdong; Zhang Na; Feng Yujun; Du Jinmei; Gu Yan

    2012-01-01

    Highlights: ► Shock wave induces the FE-to-AFE phase transition in PbNb(Zr,Sn,Ti)O 3 . ► Depoling current due to phase transition depends on shock pressure and load resistance. ► Shock pressure promotes the phase transition in short-circuit case. ► Increasing load resistance decreases the released charge. - Abstract: Shock-wave-enforced ferroelectric (FE)-to-antiferroelectric (AFE) phase transition releases a large electrical polarization, having application in pulse power technology. In the present work, the depoling currents under shock wave compression were investigated in Pb 0.99 [(Zr 0.90 Sn 0.10 ) 0.968 Ti 0.032 ] 0.98 Nb 0.02 O 3 (PZST) ceramics with composition close to the FE/AFE phase boundary. Shock wave was generated by gas-gun and propagated in a direction perpendicular to the remanent polarization. It was found that the shock pressure promoted the phase transition under the short-circuit condition. The shock pressure dependence of the released charge was associated with the evolution of FE-to-AFE phase transition. The onset of phase transition was about 0.40 GPa and complete transformation occurred at 1.23 GPa. However, the released charge decreased with increasing load resistance. The reason may be that the electric field suppresses the phase transition in uncompressed zone and/or shock induces conductivity in compressed zone. Results lay the foundation for application of PZST ceramics in shock-activated power supply.

  1. Frequency Invariability of (Pb,La)(Zr,Ti)O₃ Antiferroelectric Thick-Film Micro-Cantilevers.

    Science.gov (United States)

    An, Kun; Jin, Xuechen; Meng, Jiang; Li, Xiao; Ren, Yifeng

    2018-05-13

    Micro-electromechanical systems comprising antiferroelectric layers can offer both actuation and transduction to integrated technologies. Micro-cantilevers based on the (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ (PLZT) antiferroelectric thick film are fabricated by the micro-nano manufacturing process, to utilize the effect of phase transition induced strain and sharp phase switch of antiferroelectric materials. When micro-cantilevers made of antiferroelectric thick films were driven by sweep voltages, there were two resonant peaks corresponding to the natural frequency shift from 27.8 to 27.0 kHz, before and after phase transition. This is the compensation principle for the PLZT micro-cantilever to tune the natural frequency by the amplitude modulation of driving voltage, rather than of frequency modulation. Considering the natural frequency shift about 0.8 kHz and the frequency tuning ability about 156 Hz/V before the phase transition, this can compensate the frequency shift caused by increasing temperature by tuning only the amplitude of driving voltage, when the ultrasonic micro-transducer made of antiferroelectric thick films works for such a long period. Therefore, antiferroelectric thick films with hetero-structures incorporated into PLZT micro-cantilevers not only require a lower driving voltage (no more than 40 V) than rival bulk piezoelectric ceramics, but also exhibit better performance of frequency invariability, based on the amplitude modulation.

  2. Enhanced electrocaloric effect in La-based PZT antiferroelectric ceramics

    Science.gov (United States)

    Mendez-González, Y.; Peláiz-Barranco, A.; Yang, Tongqing; Guerra, J. D. S.

    2018-03-01

    The electrocaloric effect (ECE) has been investigated in (Pb0.98La0.02)(Zr0.95Ti0.05)0.995O3 antiferroelectric ceramics obtained via the solid-state reaction method. The results from indirect measurements across the temperature range considered reveal a large electrocaloric temperature change (ΔT) of approximately 5 K at 373 K. The enhanced ECE, which is significantly higher than those reported for some lead-free and lead-based electro-ceramics, was obtained by applying an electric field of 60 kV/cm lower than what has been reported for commonly studied ceramic systems. This result suggests that this system is a potential candidate for practical electrocaloric device applications.

  3. Complex Electric-Field Induced Phenomena in Ferroelectric/Antiferroelectric Nanowires

    Science.gov (United States)

    Herchig, Ryan Christopher

    Perovskite ferroelectrics and antiferroelectrics have attracted a lot of attention owing to their potential for device applications including THz sensors, solid state cooling, ultra high density computer memory, and electromechanical actuators to name a few. The discovery of ferroelectricity at the nanoscale provides not only new and exciting possibilities for device miniaturization, but also a way to study the fundamental physics of nanoscale phenomena in these materials. Ferroelectric nanowires show a rich variety of physical characteristics which are advantageous to the design of nanoscale ferroelectric devices such as exotic dipole patterns, a strong dependence of the polarization and phonon frequencies on the electrical and mechanical boundary conditions, as well as a dependence of the transition temperatures on the diameter of the nanowire. Antiferroelectricity also exists at the nanoscale and, due to the proximity in energy of the ferroelectric and antiferroelectric phases, a phase transition from the ferroelectric to the antiferroelectric phase can be facilitated through the application of the appropriate mechanical and electrical boundary conditions. While much progress has been made over the past several decades to understand the nature of ferroelectricity/antiferroelectricity in nanowires, many questions remain unanswered. In particular, little is known about how the truncated dimensions affect the soft mode frequency dynamics or how various electrical and mechanical boundary conditions might change the nature of the phase transitions in these ferroelectric nanowires. Could nanowires offer a distinct advantage for solid state cooling applications? Few studies have been done to elucidate the fundamental physics of antiferroelectric nanowires. How the polarization in ferroelectric nanowires responds to a THz electric field remains relatively underexplored as well. In this work, the aim is to to develop and use computational tools that allow first

  4. Lead-Free Antiferroelectric Silver Niobate Tantalate with High Energy Storage Performance.

    Science.gov (United States)

    Zhao, Lei; Liu, Qing; Gao, Jing; Zhang, Shujun; Li, Jing-Feng

    2017-08-01

    Antiferroelectric materials that display double ferroelectric hysteresis loops are receiving increasing attention for their superior energy storage density compared to their ferroelectric counterparts. Despite the good properties obtained in antiferroelectric La-doped Pb(Zr,Ti)O 3 -based ceramics, lead-free alternatives are highly desired due to the environmental concerns, and AgNbO 3 has been highlighted as a ferrielectric/antiferroelectric perovskite for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm -3 and high thermal stability of the energy storage density (with minimal variation of ≤±5%) over 20-120 °C, can be achieved in Ta-modified AgNbO 3 ceramics. It is revealed that the incorporation of Ta to the Nb site can enhance the antiferroelectricity because of the reduced polarizability of B-site cations, which is confirmed by the polarization hysteresis, dielectric tunability, and selected-area electron diffraction measurements. Additionally, Ta addition in AgNbO 3 leads to decreased grain size and increased bulk density, increasing the dielectric breakdown strength, up to 240 kV cm -1 versus 175 kV cm -1 for the pure counterpart, together with the enhanced antiferroelectricity, accounting for the high energy storage density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. A high energy density relaxor antiferroelectric pulsed capacitor dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

    2016-01-14

    Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

  6. Above-room-temperature ferroelectricity and antiferroelectricity in benzimidazoles

    Science.gov (United States)

    Horiuchi, Sachio; Kagawa, Fumitaka; Hatahara, Kensuke; Kobayashi, Kensuke; Kumai, Reiji; Murakami, Youichi; Tokura, Yoshinori

    2012-12-01

    The imidazole unit is chemically stable and ubiquitous in biological systems; its proton donor and acceptor moieties easily bind molecules into a dipolar chain. Here we demonstrate that chains of these amphoteric molecules can often be bistable in electric polarity and electrically switchable, even in the crystalline state, through proton tautomerization. Polarization-electric field (P-E) hysteresis experiments reveal a high electric polarization ranging from 5 to 10 μC cm-2 at room temperature. Of these molecules, 2-methylbenzimidazole allows ferroelectric switching in two dimensions due to its pseudo-tetragonal crystal symmetry. The ferroelectricity is also thermally robust up to 400 K, as is that of 5,6-dichloro-2-methylbenzimidazole (up to ~373 K). In contrast, three other benzimidazoles exhibit double P-E hysteresis curves characteristic of antiferroelectricity. The diversity of imidazole substituents is likely to stimulate a systematic exploration of various structure-property relationships and domain engineering in the quest for lead- and rare-metal-free ferroelectric devices.

  7. A Highly Selective Room Temperature NH3 Gas Sensor based on Nanocrystalline a-Fe2O3

    Directory of Open Access Journals (Sweden)

    Priyanka A. PATIL

    2017-05-01

    Full Text Available Nanocrystalline a-Fe2O3 powder was synthesized by simple, inexpensive sol-gel method. The obtained powder was calcined at 700 0C in air atmosphere for 2 hours. The structural and morphological properties of calcined powder were studied by X-ray diffraction (XRD and Field Emission Scanning Electron Microscopy (FESEM respectively. Thermal properties of dried gel were studied by Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC. The XRD pattern of the powder confirmed the a-Fe2O3 (hematite phase of iron oxide with average crystalline size of 30.87 nm calculated from Scherrer equation. The FESEM images showed uniform wormlike morphology of a-Fe2O3 powder. TGA result indicated that a-Fe2O3 is thermodynamically stable. Room temperature NH3 sensing characteristics of a-Fe2O3 were studied for various concentration levels (250-2500 ppm of NH3 at various humid conditions. The sensor based on a-Fe2O3 exhibited good selectivity and excellent sensitivity (S=92 towards 1000 ppm of NH3 with quick response of 4 sec and fast recovery of 9 sec. Room temperature sensing mechanism is also discussed.

  8. Silver Niobate Lead-Free Antiferroelectric Ceramics: Enhancing Energy Storage Density by B-Site Doping.

    Science.gov (United States)

    Zhao, Lei; Gao, Jing; Liu, Qing; Zhang, Shujun; Li, Jing-Feng

    2018-01-10

    Lead-free dielectric ceramics with high recoverable energy density are highly desired to sustainably meet the future energy demand. AgNbO 3 -based lead-free antiferroelectric ceramics with double ferroelectric hysteresis loops have been proved to be potential candidates for energy storage applications. Enhanced energy storage performance with recoverable energy density of 3.3 J/cm 3 and high thermal stability with minimal energy density variation (<10%) over a temperature range of 20-120 °C have been achieved in W-modified AgNbO 3 ceramics. It is revealed that the W 6+ cations substitute the B-site Nb 5+ and reduce the polarizability of B-site cations, leading to the enhanced antiferroelectricity, which is confirmed by the polarization hysteresis and dielectric tunability. It is believed that the polarizability of B-site cations plays a dominant role in stabilizing the antiferroelectricity in AgNbO 3 system, in addition to the tolerance factor, which opens up a new design approach to achieve stable antiferroelectric materials.

  9. Resonant x-ray scattering study of the antiferroelectric and ferrielectric phases in liquid crystal devices

    International Nuclear Information System (INIS)

    Matkin, L. S.; Watson, S. J.; Gleeson, H. F.; Pindak, R.; Pitney, J.; Johnson, P. M.; Huang, C. C.; Barois, P.; Levelut, A.-M.; Srajer, G.

    2001-01-01

    Resonant x-ray scattering has been used to investigate the interlayer ordering of the antiferroelectric and ferrielectric smectic C * subphases in a device geometry. The liquid crystalline materials studied contain a selenium atom and the experiments were carried out at the selenium K edge allowing x-ray transmission through glass. The resonant scattering peaks associated with the antiferroelectric phase were observed in two devices containing different materials. It was observed that the electric-field-induced antiferroelectric to ferroelectric transition coincides with the chevron to bookshelf transition in one of the devices. Observation of the splitting of the antiferroelectric resonant peaks as a function of applied field also confirmed that no helical unwinding occurs at fields lower than the chevron to bookshelf threshold. Resonant features associated with the four-layer ferrielectric liquid crystal phase were observed in a device geometry. Monitoring the electric field dependence of these ferrielectric resonant peaks showed that the chevron to bookshelf transition occurs at a lower applied field than the ferrielectric to ferroelectric switching transition

  10. Ferromagnetic Instability in AFe4Sb12 (A = Ca, Sr, and Ba)

    OpenAIRE

    Matsuoka, E.; Hayashi, K.; Ikeda, A.; Tanaka, K.; Takabatake, T.; Higemoto, W.; Matsumura, M.

    2004-01-01

    Magnetic, transport and thermal properties of AFe4Sb12 (A = Ca, Sr, Ba) are reported. All three compounds show a maximum in both the magnetic susceptibility and thermopower at 50 K, and a large electronic specific heat coefficient of 100 mJ/mol K2. These properties are the characteristics of a nearly ferromagnetic metal. Furthermore, a remanent moment of the order of 10-3muB/Fe was observed below 54, 48, and 40 K for A = Ca, Sr, and Ba, respectively. The volume fraction of the ferromagnetic c...

  11. Composition, ferroelectric and antiferroelectric ordering in Pb2InNbO6 crystals

    International Nuclear Information System (INIS)

    Bokov, A.A.; Raevskij, I.P.; Smotrakov, V.G.

    1984-01-01

    Effect of thermal treatment on temperatures of phase transitions and electrical properties has been studied in Pb 2 InNbO 6 crystals with the high-temperature phase transition of the order-disorder type in In and Nb cations disposition in crystallographic positions. The order-disorder transition temperature (Tsub(t) approximately 1020 deg C) has been directly determined for the first time using the method of electric conductivity investigation. It has been shown that Pb 2 InNbO 6 in the ordered state represents the antiferroelectric material with the Curie point of 195 deg C, and it represents the ferroelectric material with a smeared transition to the paraelectric phase in the temperature range of 60 deg C in the disordered state. With temperature decrease crystals with the mean ordering degree-paraelectric phase pass to the antiferroelectric phase and then to the ferroelectric phase

  12. Phase diagram of new lactic acid derivatives exhibiting ferro- and antiferroelectric phases

    Czech Academy of Sciences Publication Activity Database

    Kašpar, Miroslav; Novotná, Vladimíra; Hamplová, Věra; Pociecha, D.; Glogarová, Milada

    2008-01-01

    Roč. 35, č. 8 (2008), 975-985 ISSN 0267-8292 R&D Projects: GA AV ČR IAA100100710 Grant - others:ERDF(XE) WKP 1/1.4.3./1/2004/72/72/165/2005/U Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectricity * antiferroelectricity * liquid crystals * polymorphism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.132, year: 2008

  13. Highly tilted liquid crystalline materials possessing a direct phase transition from antiferroelectric to isotropic phase

    Energy Technology Data Exchange (ETDEWEB)

    Milewska, K.; Drzewiński, W. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Czerwiński, M., E-mail: mczerwinski@wat.edu.pl [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Dąbrowski, R. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Piecek, W. [Institute of Applied Physics, Military University of Technology, 00-908 Warsaw (Poland)

    2016-03-01

    Pure compounds and multicomponent mixtures with a broad temperature range of high tilted liquid crystalline antiferroelectric phase and a direct phase transition from antiferroelectric to isotropic phase, were obtained. X-ray diffraction analysis confirms these kinds of materials form a high tilted anticlinic phase, with a fixed layer spacing and very weak dependency upon temperature, after the transition from the isotropic phase. Due to this, not only pure orthoconic antiferroelectric liquid crystals but also those with a moderate tilt should generate a good dark state. Furthermore, due to the increased potential for forming anticlinic forces, such materials could minimize a commonly observed asymmetry of a rise and fall switching times at a surface stabilized geometry. - Highlights: • The new class of liquid crystalline materials with the direct SmC{sub A}*. • Iso phase transition were obtained. • Materials possess the layer spacing fixed and very weak dependent upon temperature. • Smectic layers without shrinkage are observed. • A good dark state can be generate in SSAFLC.

  14. Polarity of translation boundaries in antiferroelectric PbZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xian-Kui, E-mail: xiankui.wei@epfl.ch [Ceramics Laboratory, EPFL–Swiss Federal Institute of Technology, Lausanne 1015 (Switzerland); Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Center Jülich, 52425 Jülich (Germany); Jia, Chun-Lin [Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Center Jülich, 52425 Jülich (Germany); International Centre of Dielectric Research, The School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Roleder, Krystian [Institute of Physics, University of Silesia, Katowice 40007 (Poland); Setter, Nava [Ceramics Laboratory, EPFL–Swiss Federal Institute of Technology, Lausanne 1015 (Switzerland)

    2015-02-15

    Graphical abstract: Strain-free rigid model and aberration-corrected transmission electron microscopes are used to investigate the polarity of translation boundaries in antiferroelectric PbZrO{sub 3}. - Highlights: • Domain boundaries in antiferroelectric PbZrO{sub 3} show polar and antipolar property. • The antiphase boundary can split into “sub-domains”. • Polarization reversal possibly exists inside the translation boundaries. • Thermal treatment can alter morphology and density of the translation boundaries. - Abstract: The polarity of translation boundaries (TBs) in antiferroelectric PbZrO{sub 3} is investigated. We show that previous experimentally reported polar property of R{sub III-1} type TB can be well approximated by a strain-free rigid model. Based on this, the modeling investigation suggests that there are two additional polar TBs, three antipolar-like TBs and one antipolar antiphase boundary. High-resolution scanning-transmission-electron-microscopy study reveals that the straight R{sub III-1} type TB can split into “sub-domains” with possible polarization reversal, suggesting the occurrence of ferroic orders at the TBs. In addition, dependence of morphology and density of the TBs on thermal treatments is discussed according to our results.

  15. 1s2p resonant inelastic x-ray scattering in a-Fe2O3

    NARCIS (Netherlands)

    Caliebe, W.A.; Kao, C.-C.; Hastings, J.B.; Taguchi, M.; Kotani, A.; Uozumi, T.; Groot, F.M.F. de

    1998-01-01

    We report experimental and theoretical results on the Fe K edge x-ray absorption spectrum and 1s2p resonant inelastic x-ray scattering (RIXS) spectra in a-Fe2O3 . The results are interpreted using an FeO6^9- cluster model with intra-atomic multiplet coupling and interatomic covalency

  16. Stabilized antiferroelectric phase in lanthanum-doped (Na1/2Bi1/2)TiO3

    Science.gov (United States)

    Yi, Jae Yun; Lee, Jung-Kun

    2011-10-01

    Phase transition behaviour of La-modified sodium bismuth titanate ceramics [(Na0.5Bi0.5)1-1.5xV0.5xLax]TiO3 (NBLT) was investigated. The two anomalies in ɛr(T) and DSC analysis indicated that lower temperature phase transitions below 200 °C became pronounced with La additions. The polarization relaxation of ɛr(T) and double hysteresis loops showed that the intermediate region between two dielectric anomalies was the antiferroelectric modulated phase. The origin of the modulated antiferroelectric state was discussed in terms of disordering effects of the La ions and cation vacancies. With increasing La content, the long-range symmetry of the dipoles in the ferroelectric phase was disturbed in the intermediate region. The competition between rhombohedral ferroelectric phase and tetragonal paraelectric phase contributed to the formation of a modulated antiferroelectric phase in NBLT ceramics.

  17. Stabilized antiferroelectric phase in lanthanum-doped (Na1/2Bi1/2)TiO3

    International Nuclear Information System (INIS)

    Yi, Jae Yun; Lee, Jung-Kun

    2011-01-01

    Phase transition behaviour of La-modified sodium bismuth titanate ceramics [(Na 0.5 Bi 0.5 ) 1-1.5x V 0.5x La x ]TiO 3 (NBLT) was investigated. The two anomalies in ε r (T) and DSC analysis indicated that lower temperature phase transitions below 200 deg. C became pronounced with La additions. The polarization relaxation of ε r (T) and double hysteresis loops showed that the intermediate region between two dielectric anomalies was the antiferroelectric modulated phase. The origin of the modulated antiferroelectric state was discussed in terms of disordering effects of the La ions and cation vacancies. With increasing La content, the long-range symmetry of the dipoles in the ferroelectric phase was disturbed in the intermediate region. The competition between rhombohedral ferroelectric phase and tetragonal paraelectric phase contributed to the formation of a modulated antiferroelectric phase in NBLT ceramics.

  18. Flexoelectricity and piezoelectricity: the reason for the rich variety of phases in antiferroelectric smectic liquid crystals.

    Science.gov (United States)

    Cepic, M; Zeks, B

    2001-08-20

    The free energy of antiferroelectric smectic liquid crystals which takes into account polar order explicitly is presented. Steric, van der Waals, piezoelectric, and flexoelectric interactions to the nearest layers, and dipolar electrostatic interactions to the nearest and to the next-nearest layers, induce indirect tilt interactions with chiral and achiral properties, which extend to the third- and to the fourth-nearest layers. Although the strength of microscopic interactions changes monotonically with decreasing temperature, the effective interlayer interactions change nonmonotonically and give rise to a nonmonotonic change of the modulation period through various phases. Increased chirality changes the phase sequence.

  19. Electro-optic and dielectric properties of new binary ferroelectric and antiferroelectric liquid crystalline mixtures

    Czech Academy of Sciences Publication Activity Database

    Fitas, J.; Marzec, M.; Kurp, K.; Żurowska, M.; Tykarska, M.; Bubnov, Alexej

    2017-01-01

    Roč. 44, č. 9 (2017), s. 1468-1476 ISSN 0267-8292 R&D Projects: GA MŠk(CZ) LD14007; GA ČR GA15-02843S Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : liquid crystals * ferroelectric and antiferroelectric phase * binary mixture * dielectric spectroscopy * switching time * tilt angle Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 2.661, year: 2016

  20. Antiferroelectric surface layers in a liquid crystal as observed by synchrotron x-ray scattering

    DEFF Research Database (Denmark)

    Gramsbergen, E. F.; de Jeu, W. H.; Als-Nielsen, Jens Aage

    1986-01-01

    The X-ray reflectivity form the surface of a liquid crystal with terminally polar (cyano substituted) molecules has been studied using a high-resolution triple-axis X-ray spectrometer in combination with a synchrotron source. It is demonstrated that at the surface of the smectic Al phase a few...... antiferroelectric double layers develop that can be distinguished from the bulk single layer structure. A model is developed that separates the electron density in a contribution from the molecular form factor, and from the structure factor of the mono- and the bilayers, respectively. It shows that (i) the first...

  1. Antiferroelectric phase in liquid crystalline compounds with azo group in their molecular core

    Czech Academy of Sciences Publication Activity Database

    Kašpar, Miroslav; Novotná, Vladimíra; Hamplová, Věra; Podoliak, Natalia; Nonnenmacher, D.; Giesselmann, F.; Glogarová, Milada

    2011-01-01

    Roč. 38, č. 3 (2011), s. 309-315 ISSN 0267-8292 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047 Grant - others:German Czech bilateral program(DE) D4-CZ5/2010-2011; GA UK(CZ) SVV-2011-263303 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * antiferroelectricity * azo linkage group * photosensitivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.858, year: 2011

  2. Antiferromagnetism, structural instability and frustration in intermetallic AFe4X2 systems

    Science.gov (United States)

    Rosner, Helge; Bergmann, Christoph; Weber, Katharina; Kraft, Inga; Mufti, N.; Klauss, Hans-Henning; Dellmann, T.; Woike, T.; Geibel, Christoph

    2013-03-01

    Magnetic systems with reduced dimensionality or frustration attract strong interest because these features lead to an increase of quantum fluctuations and often result in unusual properties. Here, we present a detailed study of the magnetic, thermodynamic, and structural properties of the intermetallic AFe4X2 compounds (A=Sc,Y,Lu,Zr; X=Si,Ge) crystallizing in the ZrFe4Si2 structure type. Our results evidence that these compounds cover the whole regime from frustrated AFM order up to an AFM quantum critical point. Susceptibility χ(T), specific heat, resistivity, and T-dependent XRD measurements were performed on polycrystalline samples. In all compounds we observed a Curie-Weiss behavior in χ(T) at high T indicating a paramagnetic moment of about 3μB/Fe. Magnetic and structural transitions as previously reported for YFe4Ge2 occur in all compounds with trivalent A. However, transition temperatures, nature of the transition as well as the relation between structural and magnetic transitions change significantly with the A element. Low TN's and large θCW /TN ratios confirm the relevance of frustration. The results are analyzed and discussed with respect to electronic, structural and magnetic instabilities applying DFT calculations. Financial support from the DFG (GRK 1621) is acknowledged

  3. Associations between active trachoma and community intervention with Antibiotics, Facial cleanliness, and Environmental improvement (A,F,E.

    Directory of Open Access Journals (Sweden)

    Jeremiah Ngondi

    2008-04-01

    Full Text Available Surgery, Antibiotics, Facial cleanliness and Environmental improvement (SAFE are advocated by the World Health Organization (WHO for trachoma control. However, few studies have evaluated the complete SAFE strategy, and of these, none have investigated the associations of Antibiotics, Facial cleanliness, and Environmental improvement (A,F,E interventions and active trachoma. We aimed to investigate associations between active trachoma and A,F,E interventions in communities in Southern Sudan.Surveys were undertaken in four districts after 3 years of implementation of the SAFE strategy. Children aged 1-9 years were examined for trachoma and uptake of SAFE assessed through interviews and observations. Using ordinal logistic regression, associations between signs of active trachoma and A,F,E interventions were explored. Trachomatous inflammation-intense (TI was considered more severe than trachomatous inflammation-follicular (TF. A total of 1,712 children from 25 clusters (villages were included in the analysis. Overall uptake of A,F,E interventions was: 53.0% of the eligible children had received at least one treatment with azithromycin; 62.4% children had a clean face on examination; 72.5% households reported washing faces of children two or more times a day; 73.1% households had received health education; 44.4% of households had water accessible within 30 minutes; and 6.3% households had pit latrines. Adjusting for age, sex, and district baseline prevalence of active trachoma, factors independently associated with reduced odds of a more severe active trachoma sign were: receiving three treatments with azithromycin (odds ratio [OR] = 0.1; 95% confidence interval [CI] 0.0-0.4; clean face (OR = 0.3; 95% CI 0.2-0.4; washing faces of children three or more times daily (OR = 0.4; 95% CI 0.3-0.7; and presence and use of a pit latrine in the household (OR = 0.4; 95% CI 0.2-0.9.Analysis of associations between the A,F,E components of the SAFE strategy and

  4. Silicon-doped hafnium oxide anti-ferroelectric thin films for energy storage

    Science.gov (United States)

    Ali, Faizan; Liu, Xiaohua; Zhou, Dayu; Yang, Xirui; Xu, Jin; Schenk, Tony; Müller, Johannes; Schroeder, Uwe; Cao, Fei; Dong, Xianlin

    2017-10-01

    Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ˜65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210-400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

  5. Deuteron NMR study of the role of ammonium ions in the antiferroelectric transition in ND4D2AsO4

    International Nuclear Information System (INIS)

    Blinc, R.; Slak, J.; Luzar, M.

    1977-01-01

    The antiferroelectric transition mechanism, the temperature dependence of the quadrupole coupling tensor of the ND 4 deuterons in a partially deuterated NH 4 H 2 AsO 4 (ADA) single crystal is determined. The antiferroelectric transition in ADA is connected by an ordering of the 0 - H...0 hydrogen as well as by a significant distortion of the ammonium ions, the direction of which depends on the orientation of the sublattice polarization

  6. Energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Andreas, E-mail: aklein@surface.tu-darmstadt.de [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Lohaus, Christian [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Reiser, Patrick [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); InnovationLab GmbH, Speyerer Straße 4, 69115 Heidelberg (Germany); Dimesso, Lucangelo [Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Wang, Xiucai; Yang, Tongqing [Tongji University, Key Laboratory of Advanced Civil Engineering Materials (Ministry of Education), Functional Materials Research Laboratory, College of Materials Science and Engineering, Cao’an Road 4800, Shanghai 201804 (China)

    2017-06-15

    Highlights: • Energy band alignment of antiferroelectric PLZST studied by XPS. • A deconvolution procedure is applied to study band alignment of insulating materials. • Contribution of Pb 6s orbitals leads to higher valence band maximum. • Ferroelectric polarization does not contribute to valence band maximum energy. • The variation of Schottky barrier heights indicates no Fermi level pinning in PLZST. - Abstract: The energy band alignment of antiferroelectric (Pb,La)(Zr,Sn,Ti)O{sub 3} is studied with photoelectron spectroscopy using interfaces with high work function RuO{sub 2} and low work function Sn-doped In{sub 2}O{sub 3} (ITO). It is demonstrated how spectral deconvolution can be used to determine absolute Schottky barrier heights for insulating materials with a high accuracy. Using this approach it is found that the valence band maximum energy of (Pb,La)(Zr,Sn,Ti)O{sub 3} is found to be comparable to that of Pb- and Bi-containing ferroelectric materials, which is ∼1 eV higher than that of BaTiO{sub 3}. The results provide additional evidence for the occupation of the 6s orbitals as origin of the higher valence band maximum, which is directly related to the electrical properties of such compounds. The results also verify that the energy band alignment determined by photoelectron spectroscopy of as-deposited electrodes is not influenced by polarisation. The electronic structure of (Pb,La)(Zr,Sn,Ti)O{sub 3} should enable doping of the material without strongly modifying its insulating properties, which is crucial for high energy density capacitors. Moreover, the position of the energy bands should result in a great freedom of selecting electrode materials in terms of avoiding charge injection.

  7. Core-Shell Nano structure of a-Fe2O3/Fe3O4: Synthesis and Photo catalysis for Methyl Orange

    International Nuclear Information System (INIS)

    Tian, Y.; Wu, D.; Yu, B.; Jia, X.; Zhan, S.

    2011-01-01

    Fe 3 O 4 nanoparticle was synthesized in the solution involving water and ethanol. Then, a-Fe 2 O 3 shell was produced in situ on the surface of the Fe 3 O 4 nanoparticle by surface oxidation in molten salts, forming α-Fe 2 O 3 /Fe 3 O 4 core-shell nano structure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe 3 O 4 nanoparticles were oxidized. Furthermore, the obtained a-Fe 2 O 3 /Fe 3 O 4 core-shell nanoparticles were used to photo catalyse solution of methyl orange, and the results revealed that a-Fe 2 O 3 /Fe 3 O 4 nanoparticles were more efficient than the self-prepared α-Fe 2 O 3 nanoparticles. At the same time, the photo catalyzer was recyclable by applying an appropriate magnetic field.

  8. Twist deformation in anticlinic antiferroelectric structure in smectic B.sub.2./sub. imposed by the surface anchoring

    Czech Academy of Sciences Publication Activity Database

    Lejček, Lubor; Novotná, Vladimíra; Glogarová, Milada

    2008-01-01

    Roč. 35, č. 1 (2008), s. 11-19 ISSN 0267-8292 R&D Projects: GA ČR GA202/05/0431 Institutional research plan: CEZ:AV0Z10100520 Keywords : smectic liquid crystals * bent-shaped molecules * anticlinic antiferroelectric structure * ferroelectric structure * twist deformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.132, year: 2008

  9. High Energy Storage Density and Impedance Response of PLZT2/95/5 Antiferroelectric Ceramics.

    Science.gov (United States)

    Li, Bi; Liu, Qiuxiang; Tang, Xingui; Zhang, Tianfu; Jiang, Yanping; Li, Wenhua; Luo, Jie

    2017-02-08

    (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ (PLZT2/95/5) ceramics were successfully prepared via a solid-state reaction route. The dielectric properties were investigated in the temperature region of 26-650 °C. The dielectric diffuse anomaly in the dielectric relaxation was found in the high temperature region of 600-650 °C with increasing the measuring frequency, which was related to the dynamic thermal process of ionized oxygen vacancies generated in the high temperature. Two phase transition points were detected during heating, which were found to coexist from 150 to 200 °C. Electric field induced ferroelectric to antiferroelectric phase transition behavior of the (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ ceramics was investigated in this work with an emphasis on energy storage properties. A recoverable energy-storage density of 0.83 J/cm³ and efficiency of 70% was obtained in (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ ceramics at 55 kV/cm. Based on these results, (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ ceramics with a large recoverable energy-storage density could be a potential candidate for the applications in high energy-storage density ceramic capacitors.

  10. High Energy Storage Density and Impedance Response of PLZT2/95/5 Antiferroelectric Ceramics

    Directory of Open Access Journals (Sweden)

    Bi Li

    2017-02-01

    Full Text Available (Pb0.97La0.02(Zr0.95Ti0.05O3 (PLZT2/95/5 ceramics were successfully prepared via a solid-state reaction route. The dielectric properties were investigated in the temperature region of 26–650 °C. The dielectric diffuse anomaly in the dielectric relaxation was found in the high temperature region of 600–650 °C with increasing the measuring frequency, which was related to the dynamic thermal process of ionized oxygen vacancies generated in the high temperature. Two phase transition points were detected during heating, which were found to coexist from 150 to 200 °C. Electric field induced ferroelectric to antiferroelectric phase transition behavior of the (Pb0.97La0.02(Zr0.95Ti0.05O3 ceramics was investigated in this work with an emphasis on energy storage properties. A recoverable energy-storage density of 0.83 J/cm3 and efficiency of 70% was obtained in (Pb0.97La0.02(Zr0.95Ti0.05O3 ceramics at 55 kV/cm. Based on these results, (Pb0.97La0.02(Zr0.95Ti0.05O3 ceramics with a large recoverable energy-storage density could be a potential candidate for the applications in high energy-storage density ceramic capacitors.

  11. Formulation of electroclinic, ferroelectric and antiferroelectric liquid crystal mixtures suitable for display devices

    Science.gov (United States)

    Debnath, Asim; Goswami, Debarghya; Mandal, Pradip Kumar

    2018-04-01

    Most of the liquid crystal display (LCD) devices starting from simplest wrist watches or calculators to complex laptops or flat TV sets are based on nematics. Although a tremendous improvement in the quality of display as well as reduction of manufacturing cost has taken place over the years, there are many issues which the LC industry is trying hard to address. Ferroelectric liquid crystals (FLC) are of current interest in the LCD industry since among various other advantages FLC based displays have micro-second order switching compared to milli-second order switching in nematic based displays. To meet the market demand much effort has been made to optimize the physical parameters of FLCs, such as temperature range, spontaneous polarization (PS), helical pitch (p), switching time (τ), tilt angle (θ) and rotational viscosity (γ). Multicomponent mixtures are, therefore, formulated to optimize all the required properties for practical applications since no single FLC compound can satisfy the above requirements. To the best of our knowledge electroclinic, ferroelectric and antiferroelectric liquid crystal mixtures have been formulated first time by any Indian group which have properties suitable for FLC based display devices and at par with mixtures used in the industry.

  12. Effect of hydrostatic pressure on the antiferroelectric phase transitions in ammonium dihydrogen arsenate NH4H2AsO4 and deuterated analogue

    International Nuclear Information System (INIS)

    Gesi, Kazuo; Ozawa, Kunio

    1984-01-01

    Effect of hydrostatic pressure on the antiferroelectric phase transitions in NH 4 H 2 AsO 4 and deuterated analogue (deuterium concentration --80%) was studied by dielectric constant measurements at high pressures up to about 0.8GPa. The transition temperature linearly decreases with increasing pressure with the ratios of -19.7K GPa -1 and -14.5K GPa -1 for NH 4 H 2 AsO 4 and the deuterated compound, respectively. The pressure effect is compared with previously reported results of other KH 2 PO 4 -type ferro- and antiferroelectric crystals. (author)

  13. Preferential Creation of Polar Translational Boundaries by Interface Engineering in Antiferroelectric PbZrO3 Thin Films

    OpenAIRE

    Wei XK; Vaideeswaran K; Sandu CS; Jia CL; Setter N

    2015-01-01

    Polar translational boundaries (PTBs) are preferentially created in antiferroelectric PbZrO3 films through interfacial engineering. Probe corrected scanning transmission electron microscopy studies reveal that RIII 1 and RI 1 type PTBs are favorably created in PbZrO3/BaZrO3/SrTiO3 and PbZrO3/SrTiO3 films respectively. The relationship between interfacial strain and the internal strain of boundaries is the driving force for the selective formation of PTBs.

  14. Point-contact spectroscopic studies on normal and superconducting AFe2As2-type iron pnictide single crystals

    International Nuclear Information System (INIS)

    Lu Xin; Park, W K; Greene, L H; Yuan, H Q; Chen, G F; Luo, G L; Wang, N L; Sefat, A S; McGuire, M A; Jin, R; Sales, B C; Mandrus, D; Gillett, J; Sebastian, Suchitra E

    2010-01-01

    Point-contact Andreev reflection spectroscopy is applied to investigate the gap structure in iron pnictide single-crystal superconductors of the AFe 2 As 2 (A = Ba, Sr) family ('Fe-122'). The observed point-contact junction conductance curves, G(V), can be divided into two categories: one where Andreev reflection is present for both (Ba 0.6 K 0.4 )Fe 2 As 2 and Ba(Fe 0.9 Co 0.1 ) 2 As 2 , and the other with a V 2/3 background conductance universally observed, extending even up to 100 meV for Sr 0.6 Na 0.4 Fe 2 As 2 and Sr(Fe 0.9 Co 0.1 ) 2 As 2 . The latter is also observed in point-contact junctions on the nonsuperconducting parent compound BaFe 2 As 2 and superconducting (Ba 0.6 K 0.4 )Fe 2 As 2 crystals. Mesoscopic phase-separated coexistence of magnetic and superconducting orders is considered to explain distinct behaviors in the superconducting samples. For Ba 0.6 K 0.4 Fe 2 As 2 , double peaks due to Andreev reflection with a strongly sloping background are frequently observed for point contacts on freshly cleaved c-axis surfaces. If normalized using a background baseline and analyzed using the Blonder-Tinkham-Klapwijk model, the data show a gap size of ∼ 3.0-4.0 meV with 2Δ 0 /k B T c ∼ 2.0-2.6, consistent with the smaller gap size reported for the LnFeAsO family ('Fe-1111'). For the Ba(Fe 0.9 Co 0.1 ) 2 As 2 , the G(V) curves typically display a zero-bias conductance peak.

  15. Influence of ionic conductivity on in-phase and anti-phase motions of antiferroelectric liquid crystals

    International Nuclear Information System (INIS)

    Das, D.; Majumder, T.P.; Ghosh, N.K.

    2014-01-01

    The in-phase and anti-phase motions of antiferroelectric liquid crystals were changed due to the influence of charge density associated with the layer modulation modifying the elastic behaviour. The elastic constant was changed because of the coupling between charge density variation and variation of azimuthal angle (ϕ). We obtained theoretically a modified elastic constant depending on the variation of charge density in both in-phase and anti-phase motions. The theoretically elastic constant decreases with the increase of the coupling coefficient between charge density and in-phase azimuthal angle (ϕ a ). We theoretically accounted the dependence of dielectric strength for both relaxations depending on the effective elastic constant influenced by the presence of charge density and discussed the results with experimental observations

  16. Order-disorder antiferroelectric phase transition in a hybrid inorganic-organic framework with the perovskite architecture.

    Science.gov (United States)

    Jain, Prashant; Dalal, Naresh S; Toby, Brian H; Kroto, Harold W; Cheetham, Anthony K

    2008-08-13

    [(CH3)2NH2]Zn(HCOO)3, 1, adopts a structure that is analogous to that of a traditional perovskite, ABX3, with A = [(CH3)2NH2], B = Zn, and X = HCOO. The hydrogen atoms of the dimethyl ammonium cation, which hydrogen bond to oxygen atoms of the formate framework, are disordered at room temperature. X-ray powder diffraction, dielectric constant, and specific heat data show that 1 undergoes an order-disorder phase transition on cooling below 156 K. We present evidence that this is a classical paraelectric to antiferroelectric phase transition that is driven by ordering of the hydrogen atoms. This sort of electrical ordering associated with order-disorder phase transition is unprecedented in hybrid frameworks and opens up an exciting new direction in rational synthetic strategies to create extended hybrid networks for applications in ferroic-related fields.

  17. The influence of the coexistence of ferroelectric and antiferroelectric states on the lead lanthanum zirconate titanate crystal structure

    International Nuclear Information System (INIS)

    Ishchuk, V M; Baumer, V N; Sobolev, V L

    2005-01-01

    We present results of detailed investigation of the crystal structure of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 solid solutions. In this letter our attention is concentrated on the series of solid solutions with x = 6% usually referred to as relaxor ferroelectrics. We have established the reasons for the non-cubic crystal structure of these solid solutions at the temperatures below T C . It is demonstrated that the peculiarities of the properties of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 depend on the position of a particular solid solution with respect to the hysteresis ferroelectric-antiferroelectric region in the 'Ti-content-temperature' phase diagram. (letter to the editor)

  18. Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yumiko; Iida, Atuso E-mail: atsuo.iida@kek.jp; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

    2001-07-21

    The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few {mu}m spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 {mu}s to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition.

  19. Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

    International Nuclear Information System (INIS)

    Takahashi, Yumiko; Iida, Atuso; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

    2001-01-01

    The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few μm spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 μs to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition

  20. Global and local structural variations near the antiferroelectric regime in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Thangavelu, Karthik [Advanced Functional Materials Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, ODF-Campus-502205 (India); Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, ODF-Campus-502205 (India); Rayaprol, S. [UGC-DAE CSR Mumbai Centre, BARC Campus, Mumbai - 400085 (India); Siruguri, V. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085 (India); Sastry, P. U.; Asthana, Saket, E-mail: asthanas@iith.ac.in

    2015-06-24

    Rietveld refinement of neutron and x-ray diffraction data of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} shows R3c phase stabilization at room temperature. The intermediate antiferroelectric region between 180°C to 280°C exhibits phase coexistence i.e R3c + Pnma, along with decrease in octahedral tilt angle and increase in unit cell volume. The local structural changes observed from Raman scattering in the A-O, Ti-O and TiO{sub 6} phonon modes favor the global structural variation. A possible antiparallel cation displacement due to Pnma phase formation leads to the origin of antiferroelectric ordering in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}.

  1. Assessment Of The Use Of Autocad Package For Teaching And Learning Engineering Drawing In Afe Babalola University Ado-Ekiti

    Directory of Open Access Journals (Sweden)

    Oluwadare Joshua Oyebode

    2015-08-01

    Full Text Available ABSTRACT Drawing is the language of engineers. Drawings encompass the architectural civil structural and mechanical professions and they are the means of conveying diagrammatic detailed aspects of the design components of a structure. This Study intends to investigate an assessment of the use of AutoCAD package for teaching and learning engineering drawing in Afe Babalola University Ado-Ekiti in Ekiti State. The investigation was carried out by administering 100 questionnaires to engineering drawing lecturers and Students of the college of engineering in the university. The Findings revealed that there are positive impacts created by AutoCAD package on teachers and Students towards the teaching and learning of AutoCAD package to teach engineering drawing in all the seven programmes in the college. Engineering drawing is done in Nigerian universities polytechnics and colleges that offer courses in the areas of technical and vocational education TVE Architecture urban and regional planning and engineering. The traditional teaching and learning of technical drawing in most Nigerian universities has been characterized by the use of such manual equipment and materials part of drawing board dividers compasses set-squares protractors drawing paper drawing pen pencil scales and eraser among others. These manual tools and materials make drawing to be more time and energy consuming. Thus the arrival of the 21st century information and communication technological facilities or technologies presented a more interesting and efficient facilities for the teaching and learning of technical drawing in institutions in Nigeria. The information and communication technologies that are utilized in the teaching and learning of technical drawing include computer hardware and software computers projectors interactive broad internet scanners and so on. These are also known as computer assisted draftingdesign tools. The details of these technological facilities

  2. Dynamic behaviour of the local layer structure of antiferroelectric liquid crystals under a high electric field measured by time-resolved synchrotron x-ray microbeam diffraction

    International Nuclear Information System (INIS)

    Takahashi, Yumiko; Iida, Atsuo; Takanishi, Yoichi; Ogasawara, Toyokazu; Ishikawa, Ken; Takezoe, Hideo

    2001-01-01

    The local layer structure response to a triangular electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with 3 ms time resolution and a few μm spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface (so-called vertical bookshelf structure). After the irreversible transformation, the rearranged layer structure shows a reversible transition between the horizontal chevron (high field, ferroelectric state) and the combination of the modified vertical and horizontal chevron (low field, antiferroelectric state) associated with the field-induced antiferroelectric-ferroelectric transition. The reversible layer structure has a smaller horizontal chevron angle (a few degrees) than that in the initial state (about 17deg). The detailed microbeam diffraction revealed that the layer structure at a low electric field consists of a broad vertical chevron with a small chevron angle and a bent bookshelf in combination with a horizontal chevron, depending on the analyzing position. The stripe texture is related to the modified horizontal chevron structure. (author)

  3. Dynamic behaviour of the local layer structure of antiferroelectric liquid crystals under a high electric field measured by time-resolved synchrotron x-ray microbeam diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yumiko [Graduate University for Advanced Studies, Tsukuba, Ibaraki (Japan); Iida, Atsuo [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Takanishi, Yoichi; Ogasawara, Toyokazu; Ishikawa, Ken; Takezoe, Hideo [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Tokyo (Japan)

    2001-05-01

    The local layer structure response to a triangular electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with 3 ms time resolution and a few {mu}m spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface (so-called vertical bookshelf structure). After the irreversible transformation, the rearranged layer structure shows a reversible transition between the horizontal chevron (high field, ferroelectric state) and the combination of the modified vertical and horizontal chevron (low field, antiferroelectric state) associated with the field-induced antiferroelectric-ferroelectric transition. The reversible layer structure has a smaller horizontal chevron angle (a few degrees) than that in the initial state (about 17deg). The detailed microbeam diffraction revealed that the layer structure at a low electric field consists of a broad vertical chevron with a small chevron angle and a bent bookshelf in combination with a horizontal chevron, depending on the analyzing position. The stripe texture is related to the modified horizontal chevron structure. (author)

  4. {sup 2}H NMR study of phase transition and hydrogen dynamics in hydrogen bonded organic antiferroelectric 55DMBP-H{sub 2}ca

    Energy Technology Data Exchange (ETDEWEB)

    Asaji, Tetsuo, E-mail: asaji@chs.nihon-u.ac.jp; Hara, Masamichi; Fujimori, Hiroki [Nihon University, Department of Chemistry, College of Humanities and Sciences (Japan); Hagiwara, Shoko [Nihon University, Department of Chemistry, Graduate School of Integrated Basic Sciences (Japan)

    2016-12-15

    Hydrogen dynamics in one-dimensional hydrogen bonded organic antiferroelectric, co-crystal of 5,5’-dimethyl-2,2’-bipyridine (55DMBP) and chloranilic acid (H{sub 2}ca), was investigated by use of {sup 2}H high resolution solid-state NMR. The two types of hydrogen bonds O-H …N and N{sup +}-H …O{sup −} in the antiferroelectric phase were clearly observed as the splitting of the side band of the {sup 2}H MAS NMR spectra of the acid-proton deuterated compound 55DMBP-D {sub 2}ca. The temperature dependence of the spin-lattice relaxation time was measured of the N{sup +}-H and O-H deuterons, respectively. It was suggested that the motion of the O-H deuteron is already in the antiferroelectric phase in the fast-motion regime in the NMR time scale, while that of the N{sup +}-H deuteron is a slow motion. In the high-temperature paraelectric phase, the both deuterons become equivalent and the fast motion of the deuterons in the NMR time scale is taking place with the activation energy of 7.9 kJ mol{sup −1}.

  5. Rapid and efficient visible light photocatalytic dye degradation using AFe2O4 (A = Ba, Ca and Sr) complex oxides

    International Nuclear Information System (INIS)

    Vijayaraghavan, T.; Suriyaraj, S.P.; Selvakumar, R.; Venkateswaran, R.; Ashok, Anuradha

    2016-01-01

    Highlights: • Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca and Sr) were synthesized by sol–gel method. • Visible light photocatalytic activity of these ferrites were studied using congo red dye degradation. • BaFe 2 O 4 exhibited the best photocatalytic activity under visible light (xenon lamp) irradiation; CaFe 2 O 4 was the best photocatalyst under natural sun light irradiation. - Abstract: Photocatalytic activity of spinel type complex oxides has been investigated in this study. Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca, Sr) were synthesized by sol–gel method. Structural characterizations reveal that the synthesized ferrites have orthorhombic crystal structures with different space groups and cell dimensions when they have different alkaline earth metals in their A site. All the synthesized ferrites exhibited their bandgap in the range 2.14–2.19 eV. Their photocatalytic activities were studied using congo red dye under sunlight and xenon lamp radiation. The substitution of Ba, Ca and Sr at A site of these ferrites had varying impact on dye degradation process. Under xenon lamp irradiation, BaFe 2 O 4 exhibited the highest percentage of dye degradation (92% after 75 min). However, CaFe 2 O 4 showed the fastest degradation of the dye (70% within 15 min). In the absence of irradiation, SrFe 2 O 4 showed the highest dye adsorption (44% after 75 min).

  6. Scanning Tunneling Microscopy Study of Carbon Tetrachloride Adsorption and Degradation on a Natural a-Fe2O3(0001) Surface in Ultrahigh Vacuum

    Science.gov (United States)

    Taeg Rim, Kwang; Fitts, Jeffrey; Adib, Kaveh; Camillone, Nicholas, III; Schlosser, Peter; Osgood, Richard, Jr.; Flynn, George; Joyce, Stephen

    2001-03-01

    Scanning tunneling microscopy and low energy electron diffraction have been used to study a natural a-Fe2O3(0001) surface and the adsorption and degradation of carbon tetrachloride on the reduced Fe3O4(111) terminated surface. A natural a-Fe2O3 (0001) surface was prepared by repeated cycles of Ar+ ion sputtering and annealing in vacuum or in O2 at 850 K. STM images and a LEED pattern indicate that an Fe3O4(111) terminated surface and a bi-phase can be formed depending on annealing conditions. The Fe3O4(111) terminated surface was dosed with CCl4 at room temperature, and flashed up to 590 K and 850 K. STM images show adsorbates on the surface at room temperature and the degradation products of CCl4 are isolated on the surface as the flashing temperature increases up to 850 K. Results from a companion temperature programmed desorption investigation are used in conjunction with the STM images to propose site specific reactions of CCl4 on the Fe3O4(111) terminated surface.

  7. Attestation in self-propagating combustion approach of spinel AFe_2O_4 (A = Co, Mg and Mn) complexes bearing mixed oxidation states: Magnetostructural properties

    International Nuclear Information System (INIS)

    Bennet, J.; Tholkappiyan, R.; Vishista, K.; Jaya, N. Victor; Hamed, Fathalla

    2016-01-01

    Highlights: • Spinel type ferrite compounds AFe_2O_4 (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel. • To investigate and confirms the presence of phases in the synthesized ferrite nanoparticles by XRD and FTIR analysis. • The formation of mixed oxidation state of cobalt (Co"2"+ and Co"3"+), iron (Fe"2"+ and Fe"3"+) and manganese (Mn"2"+ and Mn"3"+) ions were studied and confirmed from XPS analysis. • The magnetic properties of the synthesized ferrites were studied by VSM measurement. - Abstract: Spinel type nano-sized ferrite compounds AFe_2O_4 (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel at 400 °C under air atmosphere for 4 h. The crystal structure, chemical composition, morphology and magnetic properties of the synthesized samples were characterized by X−ray diffraction, Fourier transform infrared spectroscopy, X−ray photoelectron spectroscopy, Energy dispersive X−ray, Scanning and Transmission electron microscopy and vibrating sample magnetometer. The chemical reaction and role of fuel on the nanoparticles formation were discussed. The XRD pattern of the synthesized samples shows the formation of pure phase with average crystallite size of 97, 57 and 98 nm from Scherrer formula and 86, 54 and 87 nm from Williamson and Hall (W–H) formula respectively. FTIR absorption spectra revealed that the presence of strong absorption peaks near 400–600 cm"−"1 corresponds to tetrahedral and octahedral complex of spinel ferrites. The relative concentrations of electronic states of elements such as cobalt (Co"2"+ and Co"3"+), iron (Fe"2"+ and Fe"3"+) and manganese (Mn"2"+ and Mn"3"+) oxidation states were studied from XPS and it is found that 55% of Fe ions are in Fe"2"+ state and the remaining is in Fe"3"+ state and thus the cationic distribution of Fe ions occurred in both tetrahedral and octahedral sites. SEM analysis

  8. Rapid and efficient visible light photocatalytic dye degradation using AFe{sub 2}O{sub 4} (A = Ba, Ca and Sr) complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraghavan, T. [PSG Institute of Advanced Studies, Coimbatore 641004 (India); Suriyaraj, S.P.; Selvakumar, R. [Nanobiotechnology Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Venkateswaran, R. [PSG Institute of Advanced Studies, Coimbatore 641004 (India); Ashok, Anuradha, E-mail: anu@psgias.ac.in [PSG Institute of Advanced Studies, Coimbatore 641004 (India)

    2016-08-15

    Highlights: • Alkaline earth ferrites AFe{sub 2}O{sub 4} (A = Ba, Ca and Sr) were synthesized by sol–gel method. • Visible light photocatalytic activity of these ferrites were studied using congo red dye degradation. • BaFe{sub 2}O{sub 4} exhibited the best photocatalytic activity under visible light (xenon lamp) irradiation; CaFe{sub 2}O{sub 4} was the best photocatalyst under natural sun light irradiation. - Abstract: Photocatalytic activity of spinel type complex oxides has been investigated in this study. Alkaline earth ferrites AFe{sub 2}O{sub 4} (A = Ba, Ca, Sr) were synthesized by sol–gel method. Structural characterizations reveal that the synthesized ferrites have orthorhombic crystal structures with different space groups and cell dimensions when they have different alkaline earth metals in their A site. All the synthesized ferrites exhibited their bandgap in the range 2.14–2.19 eV. Their photocatalytic activities were studied using congo red dye under sunlight and xenon lamp radiation. The substitution of Ba, Ca and Sr at A site of these ferrites had varying impact on dye degradation process. Under xenon lamp irradiation, BaFe{sub 2}O{sub 4} exhibited the highest percentage of dye degradation (92% after 75 min). However, CaFe{sub 2}O{sub 4} showed the fastest degradation of the dye (70% within 15 min). In the absence of irradiation, SrFe{sub 2}O{sub 4} showed the highest dye adsorption (44% after 75 min).

  9. Biaxial and antiferroelectric structure of the orthogonal smectic phase of a bent-shaped molecule and helical structure in a chiral mixture system

    Science.gov (United States)

    Kang, Sungmin; Nguyen, Ha; Nakajima, Shunpei; Tokita, Masatoshi; Watanabe, Junji

    2013-05-01

    We examined the biaxial and antiferroelectric properties in the Smectic-APA (Sm-APA) phase of bent-shaped DC-S-8. The biaxiality, which results from the existence of a secondary director, was well established from birefringence observations in the homeotropically aligned Sm-APA. By entering into Sm-APA phase, the birefringence (Δn, difference between two refractive indices of short axes) continuously increased from 0 to 0.02 with decreasing temperature. The antiferroelectric switching and second harmonic generation (SHG) activity on the field-on state were also observed in the Sm-APA phase, and the evaluated spontaneous polarization (PS) value strongly depended on temperature. The temperature dependence of Δn and PS resembles each other and follows Haller's approximation, showing that the biaxiality is due to polar packing in which the molecules are preferentially packed with their bent direction arranged in the same direction, and that the phase transition of Sm-APA to Sm-A is second order. The biaxiality was further examined in chiral Sm-APA*. Doping with chiral components induced the helical twisting of the secondary director in the Sm-APA* phase, which was confirmed by observing the reflection of the circular dichroism (CD) bands in the homeotropically aligned cell. The helical pitch of Sm-APA* is tunable in the range of 300-700 nm wavelength with a variation in the chiral content of 5 to 10 weight (wt)%.

  10. Antiferroelectric Nature of CH3NH3PbI3-xClx Perovskite and Its Implication for Charge Separation in Perovskite Solar Cells

    Science.gov (United States)

    Sewvandi, Galhenage A.; Kodera, Kei; Ma, Hao; Nakanishi, Shunsuke; Feng, Qi

    2016-07-01

    Perovskite solar cells (PSCs) have been attracted scientific interest due to high performance. Some researchers have suggested anomalous behavior of PSCs to the polarizations due to the ion migration or ferroelectric behavior. Experimental results and theoretical calculations have suggested the possibility of ferroelectricity in organic-inorganic perovskite. However, still no studies have been concretely discarded the ferroelectric nature of perovskite absorbers in PSCs. Hysteresis of P-E (polarization-electric field) loops is an important evidence to confirm the ferroelectricity. In this study, P-E loop measurements, in-depth structural study, analyses of dielectric behavior and the phase transitions of CH3NH3PbI3-xClx perovskite were carried out and investigated. The results suggest that CH3NH3PbI3-xClx perovskite is in an antiferroelectric phase at room temperature. The antiferroelectric phase can be switched to ferroelectric phase by the poling treatment and exhibits ferroelectric-like hysteresis P-E loops and dielectric behavior around room temperature; namely, the perovskite can generate a ferroelectric polarization under PSCs operating conditions. Furthermore, we also discuss the implications of ferroelectric polarization on PSCs charge separation.

  11. CAPACITACIÓN EN LIDERAZGO PARA MEJORAR LAS RELACIONES INTERPERSONALES EN EL PERSONAL QUE LABORA EN EL INSTITUTO DE EDUCACIÓN SUPERIOR TECNOLÓGICO PÚBLICO ENRIQUE LÓPEZ ALBÚJAR FERREÑAFE

    OpenAIRE

    Pérez Germán, Juan José; INSTITUTO DE EDUCACIÓN SUPERIOR TECNOLÓGICO PÚBLICO ENRIQUE LÓPEZ ALBÚJAR

    2017-01-01

    La investigación se centró en proponer un modelo de Capacitación en Liderazgo para el personal que labora en el IEST Público Enrique López Albújar de Ferreñafe, al observar deficiencias en las relaciones interpersonales, teniendo como base las teorías del liderazgo participativo y democrático de Likert, la teoría de liderazgo personal e interpersonal de Fischman, de las relaciones humanas de Chiavenato y de las relaciones humanas de Mayo. La investigación es propositiva, trabajando con 58 tra...

  12. Studies on structure and covalence effects on hyperfine interactions of AFeO sub(2) and BFeS sub(2) compounds by Moessbauer spectroscopy (A= Na, Cu, Ag, B= K, Rb, Cs, Na)

    International Nuclear Information System (INIS)

    Taft, C.A.

    1975-01-01

    The compounds AFeO sub(2) and BFeS sub(2) (A = Na, Cu, Ag, B = K, Rb, Cs, Na) were investigated by Moessbauer spectroscopy. The spectra were registered at temperature range from 4.2 sup(0) to 300 sup(0)K and magnetic transitions were observed determining correspondent temperatures by variation of hyperfine field. The electric field gradient of these compounds and perovskite type compounds (Pb sub(1-x) - Ba sub(x)) Zr O sub(3) were calculated and experimental part were determined by perturbed angular correlation, taking in account the effects of covalence, crystal lattice parameters and dipolar contributions. (M.C.K.)

  13. Degeneracy lifting due to thermal fluctuations around the frustration point between anticlinic antiferroelectric SmC(A)* and synclinic ferroelectric SmC*.

    Science.gov (United States)

    Sandhya, K L; Chandani, A D L; Fukuda, Atsuo; Vij, Jagdish K; Emelyanenko, A V; Ishikawa, Ken

    2013-01-01

    In the binary mixture phase diagram of MC881 and MC452, the borderline between anticlinic antiferroelectric SmC(A)(*) and synclinic ferroelectric SmC(*) becomes apparently parallel to the temperature ordinate axis at the critical concentration r(c). The free energy difference between SmC(A)(*) and SmC^{*} is extremely small in a wide temperature range near r(c). In such circumstances, by observing Bragg reflection spectra due to the director helical structure and electric-field-induced birefringence, we have observed the continuous change from SmC(A)(*) to SmC(*) for r/~r(c). These intriguing phenomena have been explained, successfully at least in the high-temperature region, by a thermal equilibrium between the synclinic and anticlinic orderings and the resulting Boltzmann distribution for the ratio between them; the thermal equilibrium is considered to be attained in a nonuniform defect-assisted way through solitary waves moving around dynamically. We have also discussed qualitatively an important role played by the effective long-range interlayer interactions in the low-temperature region.

  14. Attestation in self-propagating combustion approach of spinel AFe{sub 2}O{sub 4} (A = Co, Mg and Mn) complexes bearing mixed oxidation states: Magnetostructural properties

    Energy Technology Data Exchange (ETDEWEB)

    Bennet, J., E-mail: b.eenneett@gmail.com [Department of Physics, College of Engineering, Guindy, Anna University, Sardar Patel Road, Chennai,600025 (India); Tholkappiyan, R. [Department of Physics, College of Engineering, Guindy, Anna University, Sardar Patel Road, Chennai,600025 (India); Department of Physics, College of Science, UAE University, Al Ain 15551 (United Arab Emirates); Vishista, K.; Jaya, N. Victor [Department of Physics, College of Engineering, Guindy, Anna University, Sardar Patel Road, Chennai,600025 (India); Hamed, Fathalla [Department of Physics, College of Science, UAE University, Al Ain 15551 (United Arab Emirates)

    2016-10-15

    Highlights: • Spinel type ferrite compounds AFe{sub 2}O{sub 4} (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel. • To investigate and confirms the presence of phases in the synthesized ferrite nanoparticles by XRD and FTIR analysis. • The formation of mixed oxidation state of cobalt (Co{sup 2+} and Co{sup 3+}), iron (Fe{sup 2+} and Fe{sup 3+}) and manganese (Mn{sup 2+} and Mn{sup 3+}) ions were studied and confirmed from XPS analysis. • The magnetic properties of the synthesized ferrites were studied by VSM measurement. - Abstract: Spinel type nano-sized ferrite compounds AFe{sub 2}O{sub 4} (A = Co, Mg and Mn) have been successfully prepared by self-propagating combustion method using glycine as fuel at 400 °C under air atmosphere for 4 h. The crystal structure, chemical composition, morphology and magnetic properties of the synthesized samples were characterized by X−ray diffraction, Fourier transform infrared spectroscopy, X−ray photoelectron spectroscopy, Energy dispersive X−ray, Scanning and Transmission electron microscopy and vibrating sample magnetometer. The chemical reaction and role of fuel on the nanoparticles formation were discussed. The XRD pattern of the synthesized samples shows the formation of pure phase with average crystallite size of 97, 57 and 98 nm from Scherrer formula and 86, 54 and 87 nm from Williamson and Hall (W–H) formula respectively. FTIR absorption spectra revealed that the presence of strong absorption peaks near 400–600 cm{sup −1} corresponds to tetrahedral and octahedral complex of spinel ferrites. The relative concentrations of electronic states of elements such as cobalt (Co{sup 2+} and Co{sup 3+}), iron (Fe{sup 2+} and Fe{sup 3+}) and manganese (Mn{sup 2+} and Mn{sup 3+}) oxidation states were studied from XPS and it is found that 55% of Fe ions are in Fe{sup 2+} state and the remaining is in Fe{sup 3+} state and thus the cationic distribution

  15. The intermediate phase and low wave number phonon modes in antiferroelectric (Pb{sub 0.97}La{sub 0.02}) (Zr{sub 0.60}Sn{sub 0.40−y}Ti{sub y})O{sub 3} ceramics discovered from temperature dependent Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Xiaojuan; Guo, Shuang [Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Hu, Zhigao, E-mail: zghu@ee.ecnu.edu.cn [Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Chen, Xuefeng; Wang, Genshui [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Dong, Xianlin; Chu, Junhao [Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2016-05-15

    Optical phonons and phase transitions of (Pb{sub 0.97}La{sub 0.02}) (Zr{sub 0.60}Sn{sub 0.40−y}Ti{sub y})O{sub 3} (PLZST 97/2/60/40-100y/100y) ceramics with different compositions have been investigated by x-ray diffraction and temperature dependent Raman spectra. From the temperature dependence of low wavenumber phonon modes, two phase transitions (antiferroelectric orthorhombic to intermediate phase and intermediate phase to paraelectric cubic phase) were detected. The intermediate phase could be the coexistence one of antiferroelectric orthorhombic and ferroelectric rhombohedral phase. In addition, two modes (a soft mode and an anharmonic hopping central mode) were found in the high temperature paraelectric cubic phase. On cooling, the anharmonic hopping central mode splits into two modes in the terahertz range. Moreover, the antiferrodistortive mode appears in the antiferroelectric orthorhombic phase. Based on the analysis, the phase diagram of PLZST ceramics can be well improved. - Highlights: • The evolution of phonon modes in antiferroelectric PLZST ceramics. • An intermediate phase was found between orthorhombic and cubic phase. • The phase diagram of PLZST ceramics can be well improved.

  16. The role of the A ion in the Fe local structure of the AFe{sub 2}As{sub 2} systems (A=Sr, Eu, Ba): an EXAFS study

    Energy Technology Data Exchange (ETDEWEB)

    Tobia, Dina; Radaelli, Matheus; Piva, Mario Moda; Lesseux, Guilherme Gorgen; Jesus, Camilo Bruno Ramos; Urbano, Ricardo Rodrigues; Granado, Eduardo; Pagliuso, Pascoal G., E-mail: ifitobia@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Fisica Gleb Wataghin; Saleta, Martin Eduardo [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)

    2016-07-01

    Full text: The recent discovery of high-T{sub C} superconductivity on Fe-based intermetallic materials has motivated an extensive research in this area due to the rich phase diagrams that they present. The non-doped AFe{sub 2}As{sub 2} compounds (named A122) are oxygen free iron arsenides (with A= Ba, Sr, Ca, Eu). At room temperature they are paramagnetic and crystallize in a tetragonal structure. At low temperature they exhibit a spin-density-wave (SDW) ordering transition (typically 100 K < T{sub SDW} < 200 K), connected with a structural phase transition to an orthorhombic structure. These transitions are reflected as anomalies in the electric resistivity, magnetic susceptibility and specific heat data. Although the pure A122 compounds are not superconductors, in these systems, it was observed that the SDW phase can be destabilized through chemical substitution or external applied pressure, leading to the emergence of superconductivity. In particular, the atomic substitution of the alkali atoms with different ionic radii in the A site results in a change of the cell parameters and, consequently, these systems experience effects of chemical pressure. In this context, it is of great interest to investigate the role of the local distortion on the Fe-As bonds for temperatures above and below T{sub SDW}, as the Fe-As bond distance controls directly the chemical pressure on Fe and ultimately the orbital differentiation of the Fe 3d bands on the Fermi Surface of these compounds. Extended X-ray absorption fine structure (EXAFS) measurements are ideal to obtain information about the relationship between local structural distortions and the system spin dynamics. In this work we present a study of the As local environment in AFe{sub 2}As{sub 2} (for A=Eu, Sr, Ba) as a function of temperature through EXAFS measurements in the As K absorption edge. We have investigated the effects of each particular A-site ion on the Fe-As bond from a local point of view. In all cases, high

  17. Las Teorías de Elton Mayo, La Teoría de las Necesidades Humanas de Abrahan Maslow para Desarrollar las Relaciones Interpersonales, En La Institución Educativa Nº 10103 “Carmen Rosa Fernández Barrera” Del Caserío La Capilla – Pueblo Nuevo - Ferreñafe

    OpenAIRE

    Duran Chambergo, Elizabeth; Ugaz Castillo, Gustavo

    2017-01-01

    El objetivo del trabajo es diseñar estrategias para mejorar las relaciones interpersonales de los directivos y docentes de la Institución Educativa Nº 10103 “Carmen Rosa Fernández Barrera” del Caserío la Capilla – Pueblo Nuevo – Ferreñafe, que permita mejorar la gestión institucional, cuyos indicadores dan cuenta de: a) ineficientes relaciones interpersonales, b) equivocados estilos de dirección, c) falta de comunicación laboral, d) exiguas retribuciones y e) escasa disponibilidad de espacios...

  18. From antiferroelectricity to ferroelectricity in smectic mesophases ...

    Indian Academy of Sciences (India)

    are not ferroelectric in the ground state, but upon alignment within an electric field .... Figure 3. Molecular organisation within polar smectic phases and possible ways to escape from a macroscopic polarisation in mesophases built up by polar layers. .... in which the molecules adapt a twisted orientation from the top to bottom.

  19. High charge-discharge performance of Pb{sub 0.98}La{sub 0.02}(Zr{sub 0.35}Sn{sub 0.55}Ti{sub 0.10}){sub 0.995}O{sub 3} antiferroelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chenhong [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Liu, Zhen; Chen, Xuefeng; Yan, Shiguang; Cao, Fei; Dong, Xianlin; Wang, Genshui, E-mail: genshuiwang@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2016-08-21

    The energy storage performance and charge-discharge properties of Pb{sub 0.98}La{sub 0.02}(Zr{sub 0.35}Sn{sub 0.55}Ti{sub 0.10}){sub 0.995}O{sub 3} (PLZST) antiferroelectric ceramics were investigated through directly measuring the hysteresis loops and pulse discharge current-time curves. The energy density only varies 0.2% per degree from 25 °C to 85 °C, and the energy efficiency maintains at about 90%. Furthermore, an approximate calculating model of maximum power density p{sub max} was established for the discharge process. Under a relatively high working electric field (8.2 kV/mm), this ceramics possess a greatly enhanced power density of 18 MW/cm{sup 3}. Moreover, the pulse power properties did not show degradation until 1500 times of charge-discharge cycling. The large released energy density, high energy efficiency, good temperature stability, greatly enhanced power density, and excellent fatigue endurance combined together make this PLZST ceramics an ideal candidate for pulse power applications.

  20. Report on Medical Activities for the Automated AFEES Program

    Science.gov (United States)

    1976-03-10

    33.20 Diabetes mellitus 33. 12 Hypothyroidism 71 -1’ mnum mi .- i’l GU SYSTEM (Corri;B|>omJs to No. 34 on Form 88) 34. 01 Other...31 Erosion 43. 32 Gross cervical neoplasm 43. 33 Polypoid extension in cervical canal 43.40 Uterus 43.41 Infantile 43.43 Enlarged 43

  1. Dicty_cDB: AFE601 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available swyrn*t hr*w*nyn*rccwssns*ilftnfreikixky*xln*trn*kik*x Translated Amino Acid sequence (All Frames) Frame A: ...ysnr*slrftr ketllqsw*t*cscp*t*lcrpir*syrkrsfithllwyskw*fcnfthcwcsswyrn*t hr*w*nyn*rccwssns*ilftnfreiki

  2. Dicty_cDB: AFE360 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available t alignments: (bits) Value N AF305060 |AF305060.1 Dictyostelium discoideum Wiscott-Aldrich syndrome protein ...(bits) Value AF305060_1( AF305060 |pid:none) Dictyostelium discoideum Wiscott-A..

  3. Dicty_cDB: AFE377 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available iikkikxtrsvglfaslfyfffqkkx*kk--- ---xixqliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiixiixxxxii...ssssssssssssssssxssxxxxsssalxxxxiixxx iixixi Homology vs CSM-cDNA Score E Sequences producing significant al

  4. Dicty_cDB: AFE662 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available KYKKK--- ---xiiiiiiiiiiiixklxmiiixkxkmiiixxxkxxxiim*xkxmxiimxxkxxxxxi iiiixkxxxii...imxfixmk*xxxxxxxkxxkxxixxk*xxxxxlxixxkllxxkqlxxxl xxkqxxxxxxxllxxxqlixxlxxxlxixxxxkxxllxxxxlxixxlxiiiiiiiiiiii iiiiiiiiiiiixixxxxxii

  5. On the nature of phase transitions in the tetragonal tungsten bronze GdK2Nb5O15 ceramics

    International Nuclear Information System (INIS)

    Gagou, Y.; Lukyanchuk, I.; El Marssi, M.; Amira, Y.; Mezzane, D.; Courty, M.; Masquelier, C.; Yuzyuk, Yu. I.

    2014-01-01

    Phase transitions in gadolinium potassium niobate GdK 2 Nb 5 O 15 (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at T c1  = 238 °C and T c2  = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T 0 . The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence

  6. Effect of compositional variations in the lead lanthanum zirconate stannate titanate system on electrical properties

    International Nuclear Information System (INIS)

    Markowski, K.; Park, S.E.; Yoshikawa, Shoko; Cross, L.E.

    1996-01-01

    The purpose of this work was to evaluate the effect of compositional modifications on the electrical properties of lead lanthanum zirconate stannate titanate (PLZST) ceramics, as well as to examine their electrically induced phase-change behavior. Variations in the Ti:Sn ratio were evaluated. Increased Ti 4+ content produced the following: decreased switching field, related to an increased antiferroelectric-ferroelectric (AFE-FE) transition temperature; constant hysteresis (ΔE) correlated with a constant temperature of the maximum dielectric constant (T max ); a sharper dielectric-constant maximum peak; and increased room-temperature dielectric constant (K). Variations in the Zr:Sn ratio also were evaluated. Increased Zr 4+ content produced the following: increased hysteresis with increased T max , decreased maximum dielectric constant, and decreased switching field with increased AFE-FE transition temperature (T AFE-FE ). From these results, with respect to compositional modifications, the AFE-FE switching field (E AFE-FE ) and ΔE were observed to be dependent strongly on T AFE-FE and T max , respectively. Negligible change existed in the strain achievable at the switching field, which remained constant for all compositions at ∼0.16%. The significance of this research was the ability demonstrated to tailor the properties of phase-change materials through compositional modifications

  7. Phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wei; Mao, Chaoliang; Liu, Zhen; Dong, Xianlin; Cao, Fei; Wang, Genshui, E-mail: genshuiwang@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2015-03-02

    The phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} lead-free ceramics were investigated systematically. The loss tangent of poled sample shows a broad peak when heating to about 80 °C, i.e., depolarization temperature T{sub d}. The polarization-electric field hysteresis loops at different temperature exhibit the feature of ferroelectric (FE)- antiferroelectric (AFE) phase transition and the co-existence of FE and AFE phase. The pyroelectric coefficients curve confirms its diffusion behaviors. The initial hysteresis loop and switching current curves under T{sub d} indicate the co-existence of FE and AFE phase. The domain morphology of transmission electron microscopy supports the co-existence of FE and AFE phase. Our work not only exhibit that the FE and AFE phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics but also they may be helpful for further investigation on lead-free ceramics.

  8. Ferroelectric, antiferroelectric and TGB phases in lactic acid derivatives

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Kašpar, Miroslav; Hamplová, Věra; Podoliak, Natalia; Glogarová, Milada; Pociecha, D.

    2012-01-01

    Roč. 39, č. 4 (2012), s. 477-486 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GAP204/11/0723 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * lactate derivatives * TGB phases Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.959, year: 2012 http://www.tandfonline.com/doi/abs/10.1080/02678292.2011.653411

  9. Method and apparatus for bistable optical information storage for erasable optical disks

    Science.gov (United States)

    Land, Cecil E.; McKinney, Ira D.

    1990-01-01

    A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in an lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk.

  10. On the nature of phase transitions in the tetragonal tungsten bronze GdK{sub 2}Nb{sub 5}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Gagou, Y.; Lukyanchuk, I.; El Marssi, M., E-mail: mimoun.elmarssi@u-picardie.fr [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Amira, Y. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Mezzane, D. [Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Courty, M.; Masquelier, C. [Laboratoire de Réactivité et Chimie des Solides, UMR 7314, Université de Picardie Jules Verne, Pôle Scientifique, 33 rue Saint-Leu, 80039 Amiens Cedex 1 (France); Yuzyuk, Yu. I. [Faculty of Physics, Southern Federal University, 5, Zorge Str. Rostov-on-Don 344090 (Russian Federation)

    2014-02-14

    Phase transitions in gadolinium potassium niobate GdK{sub 2}Nb{sub 5}O{sub 15} (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at T{sub c1} = 238 °C and T{sub c2} = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T{sub 0}. The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence.

  11. Dimensional t-factor variation and increase of stability of the ferroelectric state in (Na0.5Bi0.5TiO3-based solid solutions

    Directory of Open Access Journals (Sweden)

    V. M. Ishchuk

    2017-10-01

    Full Text Available The influence of the B-site ion substitutions in (1−x(Bi1∕2Na1∕2TiO3–xBaTiO3 system of solid solutions on the relative stability of the antiferroelectric (AFE and ferroelectric (FE phases has been studied. The ions of zirconium, tin, and (In0.5Nb0.5, (Fe0.5Nb0.5, (Al0.5V0.5 ion complexes have been used as substituting elements. An increase in the concentration of the substituting ion results in a near linear variation in the size of the crystal lattice cell. Along with the cell size variation, a change in the relative stability of the AFE and FE phases takes place according to the changes of the tolerance factor of the solid solution. An increase in the tolerance factor leads to the increase in the temperature of the FE–AFE phase transition, and vice versa. Obtained results indicate the way for raising the temperature of the FE–AFE phase transition in (Bi1∕2Na1∕2TiO3-based solid solutions.

  12. Micro-Raman scattering and dielectric investigations of phase transitions behavior in the PbHf0.7Sn0.3O3 single crystal

    Science.gov (United States)

    Jankowska-Sumara, Irena; Ko, Jae-Hyeon; Podgórna, Maria; Oh, Soo Han; Majchrowski, Andrzej

    2017-09-01

    Raman light scattering was used to detect the sequence of transitions in a PbHf1-xSnxO3 (PHS) single crystal with x = 0.30 in a temperature range of 77-873 K. Changes of Raman spectra were observed in the vicinity of structural phase transitions: between the antiferroelectric (AFE1)-antiferroelectric (AFE2)—intermediate—paraelectric phases. Light scattering and dielectric investigations were used to find out the nature and sequence of the phase transition, as well as the large dielectric permittivity values measured at the phase transition, by searching for the soft-phonon-mode behavior. The experimentally recorded spectra were analyzed in terms of the damped-harmonic oscillator model for the phonon bands. It is demonstrated that the structural phase transformations in PHS can be considered as the result of softening of many modes, not only the ferroelectric one. It was also proved that locally broken symmetry effects are present at temperatures far above the Curie temperature and are connected with the softening of two optic modes of different nature.

  13. Water Adsorption on a-Fe2O3(0001) at Near Ambient Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Susumu

    2011-08-19

    We have investigated hydroxylation and water adsorption on {alpha}-Fe{sub 2}O{sub 3}(0001) at water vapor pressures up to 2 Torr and temperatures ranging from 277 to 647 K (relative humidity (RH) {le} 34%) using ambient-pressure X-ray photoelectron spectroscopy (XPS). Hydroxylation occurs at the very low RH of 1 x 10{sup -7} % and precedes the adsorption of molecular water. With increasing RH, the OH coverage increases up to one monolayer (ML) without any distinct threshold pressure. Depth profiling measurements showed that hydroxylation occurs only at the topmost surface under our experimental conditions. The onset of molecular water adsorption varies from {approx}2 x 10{sup -5} to {approx} 4 x 10{sup -2} % RH depending on sample temperature and water vapor pressure. The coverage of water reaches 1 ML at {approx}15% RH and increases to 1.5 ML at 34% RH.

  14. Thermal expansion behaviour and phase stability of AFe2As2 (A ...

    Indian Academy of Sciences (India)

    3Materials Research Center for Element Strategy, Tokyo Institute of .... rate determination of the atomic positions and thermal parameters. ..... is known that crystals grown out of FeAs self-flux show significantly different physical ... [5] J S Schilling, Handbook of high temperature superconductivity: Theory and experiments.

  15. Reversible a-Fe2O3 to Fe3O4 transformation during ball milling

    DEFF Research Database (Denmark)

    Linderoth, Søren; Jiang, Jianzhong; Mørup, Steen

    1997-01-01

    The transformation of hematite to magnetite by high-energy ball milling in a sealed container has been studied by Mossbauer spectroscopy and x-ray diffraction. Mechanisms for this transformation are critically discussed. The dominant mechanism is concluded to be due to bond breaking during the high...... energy ball milling followed by release of the oxygen from the vial. The reverse transformation, magnetite to hematite, is demonstrated to occur by ball milling in air. Mechanisms for this reverse transformation are also put forward....

  16. Raman study of lead zirconate titanate under uniaxial stress

    International Nuclear Information System (INIS)

    Tallant, David R.; Simpson, Regina L.; Grazier, J. Mark; Zeuch, David H.; Olson, Walter R.; Tuttle, Bruce A.

    2000-01-01

    The authors used micro-Raman spectroscopy to monitor the ferroelectric (FE) to antiferroelectric (AFE) phase transition in PZT ceramic bars during the application of uniaxial stress. They designed and constructed a simple loading device, which can apply sufficient uniaxial force to transform reasonably large ceramic bars while being small enough to fit on the mechanical stage of the microscope used for Raman analysis. Raman spectra of individual grains in ceramic PZT bars were obtained as the stress on the bar was increased in increments. At the same time gauges attached to the PZT bar recorded axial and lateral strains induced by the applied stress. The Raman spectra were used to calculate an FE coordinate, which is related to the fraction of FE phase present. The authors present data showing changes in the FE coordinates of individual PZT grains and correlate these changes to stress-strain data, which plot the macroscopic evolution of the FE-to-AFE transformation. Their data indicates that the FE-to-AFE transformation does not occur simultaneously for all PZT grains but that grains react individually to local conditions

  17. Atomistic modeling determination of placeholder binding energy of Ti, C, and N atoms on a-Fe (100) surfaces

    International Nuclear Information System (INIS)

    Wei, X J; Liu, Y P; Han, S P

    2015-01-01

    A Fe(100) surface containing Ti, C, and N was constructed and optimized to study the placeholder binding energy of the Ti, C, and N surface atoms; this was achieved by searching the transition state with the LST (linear synchronous transit) method of the CASTEP (Cambridge Serial Total Energy Package) module. Also, the authors analyzed electron structures to determine how Ti, C, and N atoms strengthen the Fe(100) surface. The results show that when Ti, C, or N atoms take placeholder alone, or simultaneously at the Fe(100) surface, the structure stability is at its best. When including Ti, C, and N as solid solutions on the Fe(100) surface, orbital electrons of Fe3d, Ti3d, C2p, and N2p hybridize near the Fermi level; the number of electronic bonding peaks increase and bonding capacity enhances. Also, a large amount of covalent bonds formed. Covalent bonds and metallic bond coexisted. (paper)

  18. An ab initio model of electron transport in hematite (a-Fe2O3) basal planes

    International Nuclear Information System (INIS)

    Rosso, Kevin M.; Smith, Dayle MA; Dupuis, Michel

    2003-01-01

    Transport of conduction electrons through basal planes of the hematite lattice was modeled as a valence alternation of iron cations using ab initio molecular orbital calculations and electron transfer theory. A cluster approach was successfully implemented to compute electron transfer rate-controlling quantities such as the reorganization energy and electronic coupling matrix element. Localization of a conduction electron at an iron lattice site is accompanied by large iron/oxygen bond length increases that give rise to a large inner-sphere component of the reorganization energy. The interaction between the reactant and product electronic states in the crossing?point configuration is substantial and leads to an adiabatic electron transfer system. Electron transfer is predicted to possess a small positive activation energy that turns out to be in excellent agreement with values deduced from conductivity measurements. Measured electron mobility can be explained in terms of nearest neighbor electron hops without significant contribution from iron atoms further away. Comparison of the predicted maximum polaron binding energy with the predicted half bandwidth indicates compliance with the small polaron condition. Therefore the localized electron treatment is appropriate to describe electron transport in this system

  19. Low-energy spin dynamics of orthoferrites AFeO3 (A  =  Y, La, Bi)

    Science.gov (United States)

    Park, Kisoo; Sim, Hasung; Leiner, Jonathan C.; Yoshida, Yoshiyuki; Jeong, Jaehong; Yano, Shin-ichiro; Gardner, Jason; Bourges, Philippe; Klicpera, Milan; Sechovský, Vladimír; Boehm, Martin; Park, Je-Geun

    2018-06-01

    YFeO3 and LaFeO3 are members of the rare-earth orthoferrites family with Pbnm space group. Using inelastic neutron scattering, the low-energy spin excitations have been measured around the magnetic Brillouin zone center. Splitting of magnon branches and finite magnon gaps (∼2 meV) are observed for both compounds, where the Dzyaloshinsky–Moriya interactions account for most of this gap with some additional contribution from single-ion anisotropy. We also make comparisons with multiferroic BiFeO3 (R3c space group), in which similar behavior was observed. By taking into account all relevant local Dzyaloshinsky–Moriya interactions, our analysis allows for the precise determination of all experimentally observed parameters in the spin-Hamiltonian. We find that different properties of the Pbnm and R3c space group lead to the stabilization of a spin cycloid structure in the latter case but not in the former, which explains the difference in the levels of complexity of magnon band structures for the respective compounds.

  20. Phenomenological description of depoling current in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression: Relaxation model

    Science.gov (United States)

    Jiang, Dongdong; Du, Jinmei; Gu, Yan; Feng, Yujun

    2012-05-01

    By assuming a relaxation process for depolarization associated with the ferroelectric (FE) to antiferroelectric (AFE) phase transition in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression, we build a new model for the depoling current, which is different from both the traditional constant current source (CCS) model and the phase transition kinetics (PTK) model. The characteristic relaxation time and new-equilibrated polarization are dependent on both the shock pressure and electric field. After incorporating a Maxwell s equation, the relaxation model developed applies to all the depoling currents under short-circuit condition and high-impedance condition. Influences of shock pressure, load resistance, dielectric property, and electrical conductivity on the depoling current are also discussed. The relaxation model gives a good description about the suppressing effect of the self-generated electric field on the FE-to-AFE phase transition at low shock pressures, which cannot be described by the traditional models. After incorporating a time- and electric-field-dependent repolarization, this model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. Finally, we make the comparison between our relaxation model and the traditional CCS model and PTK model.

  1. Electric-field-induced local structural phenomena in relaxor ferroelectric PbSc0.5Nb0.5O3 near the intermediate temperature T* studied by Raman spectroscopy

    International Nuclear Information System (INIS)

    Steilmann, T; Maier, B J; Bismayer, U; Mihailova, B; Gospodinov, M

    2014-01-01

    Raman spectroscopy at different temperatures and under an external electric field E was applied to PbSc 0.5 Nb 0.5 O 3 single crystals in order to gain further insights into the mesoscopic-scale coupling processes in perovskite-type (ABO 3 ) relaxor ferroelectrics. Parallel and cross-polarized Raman spectra were collected between 800–80 K with E applied along the cubic [1 0 0], [1 1 0] or [1 1 1] crystallographic directions. The analysis was focused on the field-induced changes in the temperature evolution of three low-energy phonon modes: the Pb-localized mode near 50 cm −1 , the Pb-BO 3 translation mode near 150 cm −1 , and the B-cation-localized mode near 250 cm −1 . The results show that competitive ferroelectric (FE) and antiferroelectric (AFE) coupling exists within the system of off-centred Pb 2+ cations, within the system of off-centred B-site cations as well as between off-centred Pb 2+ and B-site cations. The strong AFE-type coupling between Pb 2+ cations along the cubic body diagonal significantly influences the coupling between the B-site cations via the Pb-BO 3 mode and results in AFE-type behaviour of the ‘microscopic’ T* determined from the B-cation-localized mode near 250 cm −1 , which explains the previously reported non-trivial field dependence of the ‘macroscopic’ characteristic temperatures: the temperature of the dielectric-permittivity maximum T m , T*, and the Burns temperature T B . The comparative analysis between PbSc 0.5 Nb 0.5 O 3 and PbSc 0.5 Ta 0.5 O 3 indicates that two major displacive order parameters couple to form a relaxor state in B-site complex perovskites: the FE order associated with polar shifts of B-site cations and the AFE order associated with polar shifts of A-site cations. The latter penetrates through both polar and non-polar regions, but it is highly frustrated due to the high density of translation-symmetry faults in the chemical NaCl-type B-site order. The frustrated AFE order

  2. Specific heat measurements of the antiferroelectric phase transition in the mixed system KCN sub(x)Cl sub(1-x)

    International Nuclear Information System (INIS)

    Ghivelder, L.; Bastos, C.A.M.; Ribeiro, P.C.; Weid, J.P. von der.

    1984-01-01

    The specific heat of KCN sub(x)Cl sub(1-x) mixed crystals was measured for four chlorine concentrations between x=0,90 and x=1,00. The entropy change ΔS and critical temperature T sub(c) were obtained and the results are discussed in terms of the orientational motion of the CN - molecular ions. (Author) [pt

  3. E-T phase diagram of an antiferroelectric liquid crystal with re-entrand smectic C* phase

    Czech Academy of Sciences Publication Activity Database

    Na, Y.-H.; Naruse, Y.; Fukuda, N.; Orihara, H.; Fajar, A.; Hamplová, Věra; Kašpar, Miroslav; Glogarová, Milada

    2008-01-01

    Roč. 364, č. 1 (2008), s. 13-19 ISSN 0015-0193 Institutional research plan: CEZ:AV0Z10100520 Keywords : phase diagram * liquid crystals * dielectric measurements * electric field Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.562, year: 2008

  4. http://www.afe.polsl.pl/index.php/pl/733/homogeneity-of-particle-size-in-the-space-of-composite-suspension-casting.pdf

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2010-01-01

    Full Text Available The study presents the results of microstructural examinations of the Ni-Al-C alloy forming a natural Ni3Al/C composite, in which the precipitates of graphite are acting as a lubricating, slip phase. Different forms of graphite were described, starting with the fibrous shapes and ending in spheroidal forms, identical with the spheroidal graphite present in cast iron. The morphologies of graphite precipitates in the Ni3Al phase were compared to similar precipitates observed in ferrous alloys with high carbon content.

  5. Collapse of the magnetic moment under pressure of AFe{sub 2} (A=Y, Zr, Lu and Hf) in the cubic Laves phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenxu, E-mail: xwzhang@uestc.edu.cn; Zhang, Wanli

    2016-04-15

    The electronic structures of four Laves phase iron compounds (e.g. YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2}) have been calculated with a state-of-the-art full potential electronic structure code. Our theoretical work predicted that the magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its electronic origin is provided by the sharp peaks in the density of states near the Fermi level. It is shown that a first order quantum phase transition can be expected under pressure in Y(Zr, or Lu)Fe{sub 2}, while a second order one in HfFe{sub 2}. The bonding characteristics are discussed to elucidate the equilibrium lattice constant variation. The large spontaneous volume magnetostriction gives one of the most important characteristics of these compounds. Invar anomalies in these compounds can be partly explained by the current work when the fast continuous magnetic moment decrease with the decrease of the lattice constant was properly considered. This work may be as a first insight into the rich world of quantum phase transition and Invar mechanism in these Laves phase compounds. - Highlights: • Magnetic moment of YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2} collapses under pressure. • The transition in Y(Zr or Lu) Fe{sub 2} under pressure is first order. • The transition in HfFe{sub 2} under pressure is second order. • The Invar effects in the compounds can be put into the magnetostriction model.

  6. Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

    Science.gov (United States)

    Zeng, Tao; Lou, Qi-Wei; Chen, Xue-Feng; Zhang, Hong-Ling; Dong, Xian-Lin; Wang, Gen-Shui

    2015-11-01

    The phase transitions, dielectric properties, and polarization versus electric field (P-E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-xTix)O3 (0.13≤ x ≤0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P-E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content. Project supported by the National Natural Science Foundation of China (Grant Nos. 51202273, 11204304, and 11304334) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14DZ2261000).

  7. Soft antiferroelectric fluctuations in morphotropic PbZr.sub.1-x./sub.Ti.sub.x./sub.O.sub.3./sub. single crystals as evidenced by inelastic x-ray scattering

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří; Ondrejkovič, Petr; Kempa, Martin; Borissenko, E.; Krisch, M.; Long, X.; Ye, Z. -G.

    2011-01-01

    Roč. 83, č. 14 (2011), "140101-1"-"140101-4" ISSN 1098-0121 R&D Projects: GA ČR GD202/09/H041; GA ČR GAP204/10/0616; GA MŠk ME08109; GA MŠk LA 287; GA MŠk(CZ) LA10010 Grant - others:GA MŠk(CZ) SVV-2011-263307 Institutional research plan: CEZ:AV0Z10100520 Keywords : inelastic X-ray scattering * lattice dynamics * PZT * piezoelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  8. Cast dielectric composite linear accelerator

    Science.gov (United States)

    Sanders, David M [Livermore, CA; Sampayan, Stephen [Manteca, CA; Slenes, Kirk [Albuquerque, NM; Stoller, H M [Albuquerque, NM

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  9. Microstructure Study For Optimization Of Dielectric Property Of Electrical Porcelain

    International Nuclear Information System (INIS)

    Tak, S. K.; Shekhawat, M. S.; Mangal, R.

    2010-01-01

    Five sample mixtures of kaolin, ball clay, feldspar and Quartz were formulated and porcelain samples fabricated. Crystalline phases and mullite morphology were studied using XRD and SEM respectively. A composition of 30% kaolin, 15% ball clay, 30% feldspar and 25% quartz yielded a body with high dielectric strength of 19 kV/mm compare to an ISO graded product having dielectric strength 14.6 KV/mm after firing at 1225 deg. C.

  10. From appearance to essence: 10 years review of atypical amniotic fluid embolism.

    Science.gov (United States)

    Shen, Fangrong; Wang, Lu; Yang, Weiwen; Chen, Youguo

    2016-02-01

    Amniotic fluid embolism (AFE) is an unpredictable and unpreventable complication of maternity. The presentation may range from relatively subtle clinical events to sudden maternal cardiac arrest. However, the neglected diagnosis of non-classical form of AFE (atypical AFE) is very common. The aim of this study was to examine population-based regional data from Suzhou, China. Based on the analysis of all available case reports, we put forward an outline of atypical AFE and investigate whether any variation identified could be ascribed to methodology. Retrospective study from January 2004 to December 2013, 53 cases was identified from the database of Center for Disease Control (CDC) in the city of Suzhou. We investigated the presentations of atypical AFE and maternal characteristics with potential factors underlying AFE. Multiple-regression analysis was used to calculate adjusted odds ratios (ORs) and 95 % confidence intervals (CIs). The incidence of AFE was 6.91 per 100,000 deliveries (53/766,895). Seventeen deaths occurred, a mortality rate of 32 %. Atypical AFE may as the earlier stage or mild form of AFE, there was no death case in the study with timely remedy. The atypical AFE appear is obstetric hemorrhage and/or pulmonary and renal dysfunction postpartum. Hyperfibrinolysis and coagulopathy may the early laboratory findings of atypical AFE. Atypical and classical AFE shared the same risks, such as advanced maternal age, placental abnormalities, operative deliveries, eclampsia, cervical lacerations, and induction of labor. Staying alert to premonitory symptoms of AFE is critical to turn it to a remediable disease. Patient complaints such as breathlessness, chest pain, feeling cold, distress, panic, a feeling of nausea, and vomiting should elicit close attention. The management of a suspected episode of amniotic fluid embolism is generally considered to be supportive. Hysterectomy must be performed if there is further progression of symptoms. Due to advances in

  11. Identification and Analysis of a Novel Gene Cluster Involves in Fe2+ Oxidation in Acidithiobacillus ferrooxidans ATCC 23270, a Typical Biomining Acidophile.

    Science.gov (United States)

    Ai, Chenbing; Liang, Yuting; Miao, Bo; Chen, Miao; Zeng, Weimin; Qiu, Guanzhou

    2018-07-01

    Iron-oxidizing Acidithiobacillus spp. are applied worldwide in biomining industry to extract metals from sulfide minerals. They derive energy for survival through Fe 2+ oxidation and generate Fe 3+ for the dissolution of sulfide minerals. However, molecular mechanisms of their iron oxidation still remain elusive. A novel two-cytochrome-encoding gene cluster (named tce gene cluster) encoding a high-molecular-weight cytochrome c (AFE_1428) and a c 4 -type cytochrome c 552 (AFE_1429) in A. ferrooxidans ATCC 23270 was first identified in this study. Bioinformatic analysis together with transcriptional study showed that AFE_1428 and AFE_1429 were the corresponding paralog of Cyc2 (AFE_3153) and Cyc1 (AFE_3152) which were encoded by the extensively studied rus operon and had been proven involving in ferrous iron oxidation. Both AFE_1428 and AFE_1429 contained signal peptide and the classic heme-binding motif(s) as their corresponding paralog. The modeled structure of AFE_1429 showed high resemblance to Cyc1. AFE_1428 and AFE_1429 were preferentially transcribed as their corresponding paralogs in the presence of ferrous iron as sole energy source as compared with sulfur. The tce gene cluster is highly conserved in the genomes of four phylogenetic-related A. ferrooxidans strains that were originally isolated from different sites separated with huge geographical distance, which further implies the importance of this gene cluster. Collectively, AFE_1428 and AFE_1429 involve in Fe 2+ oxidation like their corresponding paralog by integrating with the metalloproteins encoded by rus operon. This study provides novel insights into the Fe 2+ oxidation mechanism in Fe 2+ -oxidizing A. ferrooxidans ssp.

  12. Modelos de regressão para estimativa da área foliar de espécies brasileiras do gênero Tillandsia L. (Bromeliaceae.

    Directory of Open Access Journals (Sweden)

    Patrícia Gabarra Mendonça

    2005-06-01

    Full Text Available O objetivo deste trabalho foi ajustar equações de regressão para estimativa da área foliar de Tillandsia spp. nativas do Brasil. Determinaram-se o comprimento ao longo da nervura principal (C, a largura máxima (L e a área foliar real de, no mínimo, 100 folhas de cada espécie, mantidas intactas nas plantas. Calcularam-se relações lineares existentes entre a área foliar real e as dimensões C, L e CL (produto entre o comprimento e a largura da folha. O modelo de regressão linear com intercepto foi o mais adequado, e as equações recomendadas, sendo AFE= área foliar estimada, foram: para Tillandsia carminea, AFE= 0,281188 + 0,562219 CL (R2= 0,7296; :Tillandsia dura, AFE= 0,891231 + 0,412457 CL (R2= 0,8432; Tillandsia gardneri, AFE= 2,54412 + 0,445525 CL (R2= 0,8662; Tillandsia geminiflora, AFE= 0,674484 + 0,444418 CL (R2= 0,8474; Tillandsia globosa, AFE= 1,9494 + 0,3804 CL (R2= 0,8178; Tillandsia grazielae, AFE= 0,518512 + 0,530259 CL (R2= 0,7608; Tillandsia kautskyi, AFE= 0,59338 + 0,374353 CL (R2= 0,6931; Tillandsia reclinata, AFE= 0,0379111 + 0,641623 CL (R2= 0,9169; Tillandsia stricta, AFE= 0,3937 + 0,4277 C (R2= 0,8661, ou AFE= 1,21336 + 0,385727 CL (R2= 0,8607; Tillandsia tenuifolia, AFE= 0,991226 + 0,402221 CL (R2= 0,7523.

  13. BOOK REVIEW FOOD AND AGRICULTURAL LAW: READINGS ON ...

    African Journals Online (AJOL)

    242 AFE BABALOLA UNIVERSITY: JOURNAL OF SUSTAINABLE DEVELOPMENT LAW ... The book, Food and Agricultural Law is Nigeria's first authoritative book ... professions including law, economics, environmental science, development,.

  14. Insight into the local magnetic environments and deuteron mobility in jarosite (AFe3(SO4)2(OD)6, A = K, Na, D3O) and hydronium alunite ((D3O)Al3(SO4)2(OD,OD2)6), from variable temperature 2H MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Heinmaa, Ivo; Samoson, Ago

    2011-01-01

    to the different temperature dependence of their isotropic shifts. An activation energy of 6.3(4) kJ/mol is determined for the D3O+ motion in the isostructural compound D3OAl3(SO4)2(OD)6. Our NMR results support theories that ascribes the spin glass behavior of (H3O)Fe3(SO4)2(OD)6 is to disorder of the D3O+ ion...... and/or a less distorted Fe coordination environment. No sign of proton transfer reactions from the D3O+ ion to the framework is observed....

  15. The small heat shock proteins from Acidithiobacillus ferrooxidans: gene expression, phylogenetic analysis, and structural modeling

    Directory of Open Access Journals (Sweden)

    Ribeiro Daniela A

    2011-12-01

    Full Text Available Abstract Background Acidithiobacillus ferrooxidans is an acidophilic, chemolithoautotrophic bacterium that has been successfully used in metal bioleaching. In this study, an analysis of the A. ferrooxidans ATCC 23270 genome revealed the presence of three sHSP genes, Afe_1009, Afe_1437 and Afe_2172, that encode proteins from the HSP20 family, a class of intracellular multimers that is especially important in extremophile microorganisms. Results The expression of the sHSP genes was investigated in A. ferrooxidans cells submitted to a heat shock at 40°C for 15, 30 and 60 minutes. After 60 minutes, the gene on locus Afe_1437 was about 20-fold more highly expressed than the gene on locus Afe_2172. Bioinformatic and phylogenetic analyses showed that the sHSPs from A. ferrooxidans are possible non-paralogous proteins, and are regulated by the σ32 factor, a common transcription factor of heat shock proteins. Structural studies using homology molecular modeling indicated that the proteins encoded by Afe_1009 and Afe_1437 have a conserved α-crystallin domain and share similar structural features with the sHSP from Methanococcus jannaschii, suggesting that their biological assembly involves 24 molecules and resembles a hollow spherical shell. Conclusion We conclude that the sHSPs encoded by the Afe_1437 and Afe_1009 genes are more likely to act as molecular chaperones in the A. ferrooxidans heat shock response. In addition, the three sHSPs from A. ferrooxidans are not recent paralogs, and the Afe_1437 and Afe_1009 genes could be inherited horizontally by A. ferrooxidans.

  16. Effects of alfalfa flavonoids on the production performance, immune system, and ruminal fermentation of dairy cows.

    Science.gov (United States)

    Zhan, Jinshun; Liu, Mingmei; Su, Xiaoshuang; Zhan, Kang; Zhang, Chungang; Zhao, Guoqi

    2017-10-01

    The objective of this study was to examine the effects of alfalfa flavonoids on the production performance, immunity, and ruminal fermentation of dairy cows. The experiments employed four primiparous Holstein cows fitted with ruminal cannulas, and used a 4×4 Latin square design. Cattle were fed total mixed ration supplemented with 0 (control group, Con), 20, 60, or 100 mg of alfalfa flavonoids extract (AFE) per kg of dairy cow body weight (BW). The feed intake of the group receiving 60 mg/kg BW of AFE were significantly higher (pcontent of milk reduced (p = 0.05) linearly as AFE supplementation was increased. The somatic cell count of milk in group receiving 60 mg/kg BW of AFE was significantly lower (pruminal fermentation parameters were not affected by AFE supplementation. Relative levels of the rumen microbe Ruminococcus flavefaciens tended to decrease (p = 0.09) quadratically, whereas those of Butyrivibrio fibrisolvens showed a tendency to increase (p = 0.07) quadratically in response to AFE supplementation. The results of this study demonstrate that AFE supplementation can alter composition of milk, and may also have an increase tendency of nutrient digestion by regulating populations of microbes in the rumen, improve antioxidant properties by increasing antioxidant enzyme activities, and affect immunity by altering the proportions of lymphocyte and neutrophil granulocytes in dairy cows. The addition of 60 mg/kg BW of AFE to the diet of dairy cows was shown to be beneficial in this study.

  17. A Lux-like Quorum Sensing System in the Extreme Acidophile Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    MARIELLA RIVAS

    2005-01-01

    Full Text Available The genome of the acidophilic, proteobacterium Acidithiobacillus ferrooxidans, contains linked but divergently oriented genes, termed afeI and afeR, whose predicted protein products are significantly similar to the LuxI and LuxR families of proteins. A possible promoter and Lux box are predicted upstream of afeI. A cloned copy of afeI, expressed in E. coli, encodes an enzyme that catalyzes the production of a diffusible compound identified by gas chromatography and mass spectrometry as an unsubstituted N-acyl homoserine lactone (AHL of chain length C14. This AHL can be detected by a reporter strain of Sinorhizobium meliloti Rm41 suggesting that it is biologically active. The reporter strain also responds to extracts of the supernatant of A. ferrooxidans grown to early stationary phase in sulfur medium indicating that a diffusible AHL is produced by this microorganism. Semi-quantitative RT-PCR experiments indicate that afeI and afeR are expressed maximally in early stationary phase and are more expressed when A. ferrooxidans is grown in sulfur- rather than iron-containing medium. Given the predicted amino acid sequence and functional properties of AfeI and AfeR it is proposed that A. ferrooxidans has a quorum sensing system similar to the LuxI-LuxR paradigm.

  18. Adverse family experiences during childhood and adolescent obesity.

    Science.gov (United States)

    Heerman, William J; Krishnaswami, Shanthi; Barkin, Shari L; McPheeters, Melissa

    2016-03-01

    To evaluate the association between adverse family experiences (AFEs) during childhood and adolescent obesity and to determine populations at highest risk for AFEs. A cross-sectional analysis was performed of the 2011-2012 National Survey of Children's Health, including children aged 10-17 years. Weighted estimates of 31,258,575 children were based on interviews with 42,239 caregivers. Caregiver reports of nine psychosocial risk factors measured AFEs during childhood. Adolescent overweight and obesity were derived by caregiver-reported child height and weight. Nearly one-third (30.5%) of children had experienced ≥2 AFEs, with geographic variation by state. The prevalence of obesity among children experiencing ≥2 AFEs was 20.4%, when compared with 12.5% among children with 0 AFEs. Adjusted survey regression models were controlled for child, parent, household, and neighborhood characteristics. Children with ≥2 AFEs in childhood were more likely to have obesity (AOR = 1.8; 95% CI = 1.47-2.17; P Adolescents in this national sample who were exposed to greater numbers of AFEs in childhood also had higher rates of overweight and obesity. Geographic variation and differential associations based on race/ethnicity identified children at greatest risk. © 2016 The Obesity Society.

  19. H.V. support structure of 3MVDC generator and its protection from HV discharges in vacuum and SF6 gas for DC electron accelerator

    International Nuclear Information System (INIS)

    Sharma, D.K.; Rajan, R.N.; Srivastava, S.K.; Dewangan, S.; Jayaprakash, D.; Bakhtsingh, R.I.; Acharya, S.; Gantayet, L.M.

    2014-01-01

    Accelerator and Pulse Power Division of BARC has developed a DC electron accelerator for cross linking of polymers, medical sterilisation, preservation of food. The demonstration of stack-gas cleanup for green power generation has been demonstrated successfully. The support structure of the 3MVDC voltage generator is made of Perspex for high dielectric strength, easy availability of raw material, excellent radiation resistance and long term dimensional stability. This paper describes the salient design features of the High voltage support structure in brief. (author)

  20. Dielectric strength of SiO2 in a CMOS transistor structure

    International Nuclear Information System (INIS)

    Soden, J.M.

    1979-01-01

    The distribution of experimental dielectric strengths of SiO 2 gate dielectric in a CMOS transistor structure is shown to be composed of a primary, statistically-normal distribution of high dielectric strength and a secondary distribution spread through the lower dielectric strength region. The dielectric strength was not significantly affected by high level (1 x 10 6 RADS (Si)) gamma radiation or high temperature (200 0 C) stress. The primary distribution breakdowns occurred at topographical edges, mainly at the gate/field oxide interface, and the secondary distribution breakdowns occurred at random locations in the central region of the gate

  1. H.V. support structure of 3MVDC generator and its protection from HV discharges in vacuum and SF6 gas for DC electron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, D.K.; Rajan, R.N.; Srivastava, S.K.; Dewangan, S.; Jayaprakash, D.; Bakhtsingh, R.I.; Acharya, S.; Gantayet, L.M., E-mail: dksharma@barc.gov.in [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-07-01

    Accelerator and Pulse Power Division of BARC has developed a DC electron accelerator for cross linking of polymers, medical sterilisation, preservation of food. The demonstration of stack-gas cleanup for green power generation has been demonstrated successfully. The support structure of the 3MVDC voltage generator is made of Perspex for high dielectric strength, easy availability of raw material, excellent radiation resistance and long term dimensional stability. This paper describes the salient design features of the High voltage support structure in brief. (author)

  2. Effects of alfalfa flavonoids on the production performance, immune system, and ruminal fermentation of dairy cows

    Directory of Open Access Journals (Sweden)

    Jinshun Zhan

    2017-10-01

    Full Text Available Objective The objective of this study was to examine the effects of alfalfa flavonoids on the production performance, immunity, and ruminal fermentation of dairy cows. Methods The experiments employed four primiparous Holstein cows fitted with ruminal cannulas, and used a 4×4 Latin square design. Cattle were fed total mixed ration supplemented with 0 (control group, Con, 20, 60, or 100 mg of alfalfa flavonoids extract (AFE per kg of dairy cow body weight (BW. Results The feed intake of the group receiving 60 mg/kg BW of AFE were significantly higher (p<0.05 than that of the group receiving 100 mg/kg BW. Milk yields and the fat, protein and lactose of milk were unaffected by AFE, while the total solids content of milk reduced (p = 0.05 linearly as AFE supplementation was increased. The somatic cell count of milk in group receiving 60 mg/kg BW of AFE was significantly lower (p<0.05 than that of the control group. Apparent total-tract digestibility of neutral detergent fiber and crude protein showed a tendency to increase (0.05AFE. Methane dicarboxylic aldehyde concentration decreased (p = 0.03 linearly, whereas superoxide dismutase activity showed a tendency to increase (p = 0.10 quadratically, with increasing levels of AFE supplementation. The lymphocyte count and the proportion of lymphocytes decreased (p = 0.03 linearly, whereas the proportion of neutrophil granulocytes increased (p = 0.01 linearly with increasing levels of dietary AFE supplementation. The valeric acid/total volatile fatty acid (TVFA ratio was increased (p = 0.01 linearly with increasing of the level of AFE supplementation, the other ruminal fermentation parameters were not affected by AFE supplementation. Relative levels of the rumen microbe Ruminococcus flavefaciens tended to decrease (p = 0.09 quadratically, whereas those of Butyrivibrio fibrisolvens showed a tendency to increase (p = 0.07 quadratically in response to AFE supplementation

  3. LANSCE-R WIRE-SCANNER ANALOG FRONT-END ELECTRONICS

    International Nuclear Information System (INIS)

    Gruchalla, Michael E.

    2011-01-01

    A new AFE is being developed for the new LANSCE-R wire-scanner systems. The new AFE is implemented in a National Instruments Compact RIO (cRIO) module installed a BiRa 4U BiRIO cRIO chassis specifically designed to accommodate the cRIO crate and all the wire-scanner interface, control and motor-drive electronics. A single AFE module provides interface to both X and Y wire sensors using true DC coupled transimpedance amplifiers providing collection of the wire charge signals, real-time wire integrity verification using the normal dataacquisition system, and wire bias of 0V to +/-50V. The AFE system is designed to accommodate comparatively long macropulses (>1ms) with high PRF (>120Hz) without the need to provide timing signals. The basic AFE bandwidth is flat from true DC to 50kHz with a true first-order pole at 50kHz. Numeric integration in the cRIO FPGA provides real-time pulse-to-pulse numeric integration of the AFE signal to compute the total charge collected in each macropulse. This method of charge collection eliminates the need to provide synchronization signals to the wire-scanner AFE while providing the capability to accurately record the charge from long macropulses at high PRF.

  4. Plasma polymerized high energy density dielectric films for capacitors

    Science.gov (United States)

    Yamagishi, F. G.

    1983-01-01

    High energy density polymeric dielectric films were prepared by plasma polymerization of a variety of gaseous monomers. This technique gives thin, reproducible, pinhole free, conformable, adherent, and insoluble coatings and overcomes the processing problems found in the preparation of thin films with bulk polymers. Thus, devices are prepared completely in a vacuum environment. The plasma polymerized films prepared all showed dielectric strengths of greater than 1000 kV/cm and in some cases values of greater than 4000 kV/cm were observed. The dielectric loss of all films was generally less than 1% at frequencies below 10 kHz, but this value increased at higher frequencies. All films were self healing. The dielectric strength was a function of the polymerization technique, whereas the dielectric constant varied with the structure of the starting material. Because of the thin films used (thickness in the submicron range) surface smoothness of the metal electrodes was found to be critical in obtaining high dielectric strengths. High dielectric strength graft copolymers were also prepared. Plasma polymerized ethane was found to be thermally stable up to 150 C in the presence of air and 250 C in the absence of air. No glass transitions were observed for this material.

  5. 3. Multiple Antibiotic Resistance Index ofEscherichiaColi Isolates in ...

    African Journals Online (AJOL)

    user

    2Department of Medical Microbiology and Parasitology, AfeBabalola University, Ado-Ekiti ... hence, antimicrobial susceptibility testing is imperative in selecting ... infections and limit its transmission. Examples .... MATERIALS AND METHODS.

  6. EDITORIAL COMMENT

    African Journals Online (AJOL)

    of The Journal of Sustainable Development Law and Policy, Afe. Babalola University ... The articles in this edition challenge us to approach sustainability in new ways. ... population to health care policy, and to copyright and literary approaches.

  7. legal status of sections 10 and 12 of the nigerian oil and gas industry

    African Journals Online (AJOL)

    Nigerians and Nigerian products.2 This move has stirred up questions on ... 130 AFE BABALOLA UNIVERSITY: JOURNAL OF SUSTAINABLE DEVELOPMENT ..... be relevant since internal taxation could affect consumer demand for a prod-.

  8. Acute Febrile Encephalopathy in Adults; a Review of 3 Prospective Trials

    Directory of Open Access Journals (Sweden)

    Sareh Sajadi

    2017-04-01

    Conclusion: Primary CNS infections including bacterial meningitis and viral meningoencephalitis account for the most causes of AFE in adult and elderly patients with the most fatality for viral agents.

  9. Amniotic fluid embolism incidence, risk factors and outcomes: a review and recommendations

    Directory of Open Access Journals (Sweden)

    Knight Marian

    2012-02-01

    Full Text Available Abstract Background Amniotic fluid embolism (AFE is a rare but severe complication of pregnancy. A recent systematic review highlighted apparent differences in the incidence, with studies estimating the incidence of AFE to be more than three times higher in North America than Europe. The aim of this study was to examine population-based regional or national data from five high-resource countries in order to investigate incidence, risk factors and outcomes of AFE and to investigate whether any variation identified could be ascribed to methodological differences between the studies. Methods We reviewed available data sources on the incidence of AFE in Australia, Canada, the Netherlands, the United Kingdom and the USA. Where information was available, the risk factors and outcomes of AFE were examined. Results The reported incidence of AFE ranged from 1.9 cases per 100 000 maternities (UK to 6.1 per 100 000 maternities (Australia. There was a clear distinction between rates estimated using different methodologies. The lowest estimated incidence rates were obtained through validated case identification (range 1.9-2.5 cases per 100 000 maternities; rates obtained from retrospective analysis of population discharge databases were significantly higher (range 5.5-6.1 per 100 000 admissions with delivery diagnosis. Older maternal age and induction of labour were consistently associated with AFE. Conclusions Recommendation 1: Comparisons of AFE incidence estimates should be restricted to studies using similar methodology. The recommended approaches would be either population-based database studies using additional criteria to exclude false positive cases, or tailored data collection using existing specific population-based systems. Recommendation 2: Comparisons of AFE incidence between and within countries would be facilitated by development of an agreed case definition and an agreed set of criteria to minimise inclusion of false positive cases for

  10. Effect of Flaxseed Meals and Extracts on Lipid Stability in a Stored Meat Product.

    Science.gov (United States)

    Waszkowiak, Katarzyna; Rudzińska, Magdalena

    2014-01-01

    Flaxseeds have been recently in focus due to the antioxidant capacity of some of their compounds. However, there is a lack of easily accessible information concerning their activity against lipid oxidation in food systems. Therefore, the aim of the study was to determine the effect of defatted meals (DFM) and the aqueous extracts (AFE) obtained from brown and golden flaxseeds on lipid oxidation in pork meatballs. Fatty acid composition, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and cholesterol content were monitored during 6 months of freezer storage. Cholesterol oxidation products were identified and quantified. Both DFM and AFE limited fatty acid and cholesterol oxidation during meatball storage. Their antioxidant effect depended on flax variety (brown or golden) and preparation type (DFM or AFE). Lower level of PV and TBARS, compared with the ones with AFE, were noted in meatballs with DFM. Both DFM and AFE, from the brown seed variety, protect the lipids against oxidation to a higher extent. During the storage, a cholesterol degradation was observed. AFE (particularly from the brown variety) limited changes in cholesterol content. Moreover, they stabilized fatty acid composition of stored meatballs. However, DFM efficiently inhibited cholesterol oxidation.

  11. Phase transformations, ionic conductivity and dipole ordering of NASICON-like double phosphates Na3M2(PO4)3 (M-Sc,Fe,Cr)

    International Nuclear Information System (INIS)

    Kalinin, V.B.

    1990-01-01

    Experimental data obtained using ceramic samples of Na 3 M 2 (PO 4 ) 3 and solid solutions on their basis have been analyzed and generalized. It is shown that isostoichiometry of Na 3 M 2 (PO 4 ) 3 compounds and different types of dipole ordering in their α-phases stimulate investigations of subsolidus regions in the systems Na 3 Sc 2 (PO 4 ) 3 -Na 3 Fe 2 (PO 4 ) 3 , Na 3 Sc 2 (PO 4 ) 3 -Na 3 Cr 2 (PO 4 ) 3 , Na 3 Fe 2 (PO 4 ) 3 -Na 3 Cr 2 (PO 4 ) 3 .It proved possible to detect changes of the properties in case of ferroelectric-antiferroelectric, antiferroelectric-antiferroelectric transitions

  12. X-ray and electron diffraction studies of the structures of pseudo-perovskite compounds Pb2(Sc,Ta)O6 and Pb2(Mg,W)O6

    International Nuclear Information System (INIS)

    Baba-Kishi, K.Z.; Cernik, R.J.

    1992-01-01

    Electron diffraction patterns, X-ray precession patterns and synchrotron Rietveld powder diffraction profiles were used to study the crystal structure of the pseudo-perovskite compound Pb 2 (Sc, Ta)O 6 (PST). The results of a Rietveld refinement and single-crystal X-ray precession studies showed that PST has a lower symmetry than the cubic Fm3m in the paraelectric state. The remarkable similarities between the crystal structures of the antiferroelectric Pb 2 (Mg, W)O 6 (PMW) and ferroelectric PST are studied in detail by electron diffraction and it is suggested that PST is a weak or frustrated antiferroelectric oxide. The influence of the degree of structural long-range order on the existence of an antiferroelectric phase transition in PST and PMW is discussed. (orig.)

  13. Phonon instabilities in NaNbO3

    International Nuclear Information System (INIS)

    Mishra, S.K.; Gupta, M.K.; Mittal, R.; Chaplot, S.L.

    2012-01-01

    NaNbO 3 has antiferroelectric structure at room temperature and exhibits unusual complex sequence of temperature and pressure driven structural phase transitions. Temperature dependent measurements from 17 to 1075 K revealed that NaNbO 3 undergoes a series of phase transitions, ranging from non-polar antiferrodistortive to ferroelectric and antiferroelectric in nature. High pressure measurements carried out up to 11 GPa at ambient temperature indicate transition from antiferroelectric to paraelectric phase. These transitions are characterized by appearance and disappearance of superlattice reflections in the powder diffraction patterns. Numerous Raman and infrared measurements are also reported in literature to gain reliable insights into, and deeper understanding of phase transition behavior. The optical measurements are limited to the Brillouin zone centre, which does not give a complete picture of the dynamics. Inelastic neutron scattering and ab-initio calculations were carried out to understand the phase transitions behaviour and their relation to the phonon spectra

  14. Inhibitory effect of fermented Arctium lappa fruit extract on the IgE-mediated allergic response in RBL‑2H3 cells.

    Science.gov (United States)

    Yoo, Jae-Myung; Yang, Ju Hye; Yang, Hye Jin; Cho, Won-Kyung; Ma, Jin Yeul

    2016-02-01

    Arctium lappa fruit has been used in traditional medicine, and it is known to exert beneficial effects, such as antioxidant, anti-inflammatory and anticancer effects. However, the effects of the Arctium lappa fruit on the allergic response remain unknown. In this study, we evaluated the anti-allergic effects of Arctium lappa fruit extract (AFE) and its fermented form (F-AFE) using immunoglobulin E (IgE)-activated RBL‑2H3 cells. To investigate the anti-allergic effects of AFE or F-AFE, we examined the release of β-hexosaminidase, a key biomarker of degranulation during an allergic reaction, and the production of pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and prostaglandin E2 (PGE2) in the cells treated with or without the above-mentioned extracts. AFE weakly inhibited the release of β-hexosaminidase, whereas F-AFE significantly suppressed the release of β-hexosaminidase in a dose-dependent manner. Consistently, F-AFE suppressed the production of TNF-α and PGE2 in a dose-dependent manner. F-AFE exerted an inhibitory effect on the production of β-hexosaminidase, TNF-α and PGE2 with an IC50 value of 30.73, 46.96 and 36.27 µg/ml, respectively. Furthermore, F-AFE inhibited the phosphorylation of Lyn, Fyn and Syk, which are involved in the FcεRI signaling pathway, that of phosphoinositide phospholipase C (PLC)γ1/2 and protein kinase C (PKC)δ, which are associated with the degranulation process, as well as that of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase 1/2 (JNK), p38 and Akt, which are associated with cytokine expression. In the late phase, F-AFE partially suppressed the phosphorylation of cytosolic phospholipase A2 (cPLA2), but not the expression of cyclooxygenase (COX)-2. To compare and identify the major components of the two extracts, we used high-performance liquid chromatography. The levels of arctigenin, one of the major compounds, were elevated 6-fold in F-AFE compared with AFE, whereas the

  15. Critical properties of a ferroelectric superlattice described by a transverse spin-1/2 Ising model

    International Nuclear Information System (INIS)

    Tabyaoui, A; Saber, M; Baerner, K; Ainane, A

    2007-01-01

    The phase transition properties of a ferroelectric superlattice with two alternating layers A and B described by a transverse spin-1/2 Ising model have been investigated using the effective field theory within a probability distribution technique that accounts for the self spin correlation functions. The Curie temperature T c , polarization and susceptibility have been obtained. The effects of the transverse field and the ferroelectric and antiferroelectric interfacial coupling strength between two ferroelectric materials are discussed. They relate to the physical properties of antiferroelectric/ferroelectric superlattices

  16. A comparison of white light laryngostroboscopy versus autofluorescence endoscopy in the evaluation of vocal fold pathology.

    Science.gov (United States)

    Caffier, Philipp P; Schmidt, Bernd; Gross, Manfred; Karnetzky, Klaus; Nawka, Tadeus; Rotter, Andreas; Seipelt, Matthias; Sedlmaier, Benedikt

    2013-07-01

    To prove the diagnostic value of autofluorescence endoscopy (AFE) and white light laryngostroboscopy (WLS) versus the gold standard microlaryngoscopy with histopathological examination in differential diagnostics of laryngeal lesions for experienced phoniatricians and laryngologists, using the PENTAX SAFE-3000 system. Exploratory cohort study. High-resolution rigid WLS was executed in 32 consecutive patients with initial manifestation of benign, precancerous, and malignant vocal fold lesions. Fiberoptic blue light AFE (SAFE-3000; λ = 408 nm) was subsequently performed by an experienced endoscopist in a blinded study setting. Findings were rated based on objective WLS and AFE parameters (e.g., phonatory vibration, mucosal wave propagation, and loss of autofluorescence). The clinically assumed WLS and AFE diagnoses were compared with the final histopathology of biopsied material taken during microlaryngoscopy. In reference to histopathological diagnosis, WLS achieved a higher sensitivity (100% vs. 94%), specificity (94% vs. 69%), and accuracy (97% vs. 81%) than AFE diagnostics. The concordance between both endoscopic techniques was 87.5% (28/32 patients); additional AFE benefits were not detectable. Significant loss of autofluorescence was observed in malignant findings clinically clearly diagnosed by WLS, but also in chronic inflammation, severe dysplasia, granulomas, vascular polyps, and glottal papillomatosis. The evaluation of vocal fold pathology by the clinically experienced examiner precisely applying WLS appears to be more reliable than diagnostics of mucosal tissue changes by means of AFE via the SAFE-3000 system as a relatively nonspecific method. Microlaryngoscopy with histopathological examination and phonomicrosurgical excision of pathologic changes remains the gold standard. © 2012 The American Laryngological, Rhinological and Otological Society, Inc.

  17. Cavallo's multiplier for in situ generation of high voltage

    Science.gov (United States)

    Clayton, S. M.; Ito, T. M.; Ramsey, J. C.; Wei, W.; Blatnik, M. A.; Filippone, B. W.; Seidel, G. M.

    2018-05-01

    A classic electrostatic induction machine, Cavallo's multiplier, is suggested for in situ production of very high voltage in cryogenic environments. The device is suitable for generating a large electrostatic field under conditions of very small load current. Operation of the Cavallo multiplier is analyzed, with quantitative description in terms of mutual capacitances between electrodes in the system. A demonstration apparatus was constructed, and measured voltages are compared to predictions based on measured capacitances in the system. The simplicity of the Cavallo multiplier makes it amenable to electrostatic analysis using finite element software, and electrode shapes can be optimized to take advantage of a high dielectric strength medium such as liquid helium. A design study is presented for a Cavallo multiplier in a large-scale, cryogenic experiment to measure the neutron electric dipole moment.

  18. Effect of resin composition to the electrical and mechanical properties of high voltage insulator material

    International Nuclear Information System (INIS)

    Totok Dermawan; Elin Nuraini; Suyamto

    2012-01-01

    A solid insulator manufacture of resins for high voltage with a variation of resin and hardener composition has been made. The purpose of research to know electrical and mechanical properties of high voltage insulator material of resin. To determine its electric properties, the material is tested its breakdown voltage and the flashover voltage that occurred on the surface. While to determine the mechanical properties were tested by measuring its strength with a tensile test. From testing with variety of mixed composition it is known that for composition between hardener and resin of 1 : 800 has most advantageous properties because it has good strength with a tensile strength of 19.86 MPa and enough high dielectric strength of 43.2 kV / mm). (author)

  19. Use of fluorocarbons in the cooling of LHC experiments

    CERN Document Server

    Pimenta dos Santos, M

    2003-01-01

    Perfluorochemicals sold by 3M under the trade name 3M Fluorinert Electronic Liquids have been used for many years as heat transfer media in a variety of industries. The suitability of these liquids for the cooling of LHC experiment originates from their high dielectric strength as well as from their chemical stability under ionizing radiation. The Fluorinerts are clear, colorless, non-flammable with low toxicity and low corrosiveness. Additionally, they offer low global waming potential – GWP – and zero ozone-depletion potential – ODP. Some examples of fluorinert application in the cooling of LHC experiments will be presented : (a) the ATLAS Inner detector C3F8 evaporative cooling system (b) the ATLAS TRF C6F14 monophase cooling system and (c) the ALICE SPD “active heat pipe” C4F10 evaporative cooling system. A brief comparison of evaporative and monophase cooling systems will be outlined.

  20. The effect of nanoclay on the rheology and dynamics of polychlorinated biphenyl.

    Science.gov (United States)

    Roy, D; Casalini, R; Roland, C M

    2015-12-28

    The thermal, rheological, and mechanical and dielectric relaxation properties of exfoliated dispersions of montmorillonite clay in a molecular liquid, polychlorobiphenyl (PCB), were studied. The viscosity enhancement at low concentrations of clay (≤5%) exceeded by a factor of 50 the increase obtainable with conventional fillers. However, the effect of the nanoclay on the local dynamics, including the glass transition temperature, was quite small. All materials herein conformed to density-scaling of the reorientation relaxation time of the PCB for a common value of the scaling exponent. A new relaxation process was observed in the mixtures, associated with PCB molecules in proximity to the clay surface. This process has an anomalously high dielectric strength, suggesting a means to exploit nanoparticles to achieve large electrical energy absorption. This lower frequency dispersion has a weaker dependence on pressure and density, consistent with dynamics constrained by interactions with the particle surface.

  1. Anisotropic dielectric response of lead zirconate crystals in the terahertz and infrared range at low temperature

    Czech Academy of Sciences Publication Activity Database

    Ostapchuk, Tetyana; Kadlec, Christelle; Kužel, Petr; Kroupa, Jan; Železný, Vladimír; Hlinka, Jiří; Petzelt, Jan; Dec, J.

    2014-01-01

    Roč. 87, 10-11 (2014), s. 1129-1137 ISSN 0141-1594 R&D Projects: GA ČR GA13-15110S Institutional support: RVO:68378271 Keywords : antiferroelectrics * infrared and terahertz spectroscopy * lead zirconate * phonons * complex dielectric permittivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.954, year: 2014

  2. Covalent Attachment of Bent-Core Mesogens to Silicon Surfaces

    NARCIS (Netherlands)

    Scheres, L.; Achten, R.; Giesbers, M.; Smet, de L.; Arafat, A.; Sudhölter, E.J.R.; Marcelis, A.T.M.; Zuilhof, H.

    2009-01-01

    Two vinyl-terminated bent core-shaped liquid crystalline molecules that exhibit thermotropic antiferroelectric SmCPA phases have been covalently attached onto a hydrogen-terminated silicon(111) surface. The surface attachment was achieved via a mild procedure from a mesitylene solution, using

  3. Multiple soft-mode vibrations of lead zirconate

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří; Ostapchuk, Tetyana; Buixaderas, Elena; Kadlec, Christelle; Kužel, Petr; Gregora, Ivan; Kroupa, Jan; Savinov, Maxim; Klíč, Antonín; Drahokoupil, Jan; Etxebarria, I.; Dec, J.

    2014-01-01

    Roč. 112, č. 19 (2014), "197601-1"-"197601-5" ISSN 0031-9007 R&D Projects: GA ČR GA13-15110S Institutional support: RVO:68378271 Keywords : antiferroelectric * soft mode * polarized spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.512, year: 2014

  4. Catching the intermediate phase in PZT 99/1 single crystals

    Czech Academy of Sciences Publication Activity Database

    Buixaderas, Elena; Ostapchuk, Tetyana; Kroupa, Jan; Savinov, Maxim; Gregora, Ivan; Hlinka, Jiří

    2014-01-01

    Roč. 87, 10-11 (2014), s. 1105-1113 ISSN 0141-1594 R&D Projects: GA ČR GA13-15110S Institutional support: RVO:68378271 Keywords : Raman spectroscopy * phonons * PZT * antiferroelectrics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.954, year: 2014

  5. Visualizing lone pairs in compounds containing heavier congeners ...

    Indian Academy of Sciences (India)

    Unknown

    Fm3 PbS provides a segue into perovskite phases of technological significance, including ... rôle of the lone pair in driving (respectively) the ferroelectric and antiferroelectric phase transitions. 2. SnO, αα-PbO ..... of compounds with d0 elements, and to N A Hill for critically reading this manuscript. The Laboratoire SPMS and ...

  6. Age at First Exposure to Football Is Associated with Altered Corpus Callosum White Matter Microstructure in Former Professional Football Players.

    Science.gov (United States)

    Stamm, Julie M; Koerte, Inga K; Muehlmann, Marc; Pasternak, Ofer; Bourlas, Alexandra P; Baugh, Christine M; Giwerc, Michelle Y; Zhu, Anni; Coleman, Michael J; Bouix, Sylvain; Fritts, Nathan G; Martin, Brett M; Chaisson, Christine; McClean, Michael D; Lin, Alexander P; Cantu, Robert C; Tripodis, Yorghos; Stern, Robert A; Shenton, Martha E

    2015-11-15

    Youth football players may incur hundreds of repetitive head impacts (RHI) in one season. Our recent research suggests that exposure to RHI during a critical neurodevelopmental period prior to age 12 may lead to greater later-life mood, behavioral, and cognitive impairments. Here, we examine the relationship between age of first exposure (AFE) to RHI through tackle football and later-life corpus callosum (CC) microstructure using magnetic resonance diffusion tensor imaging (DTI). Forty retired National Football League (NFL) players, ages 40-65, were matched by age and divided into two groups based on their AFE to tackle football: before age 12 or at age 12 or older. Participants underwent DTI on a 3 Tesla Siemens (TIM-Verio) magnet. The whole CC and five subregions were defined and seeded using deterministic tractography. Dependent measures were fractional anisotropy (FA), trace, axial diffusivity, and radial diffusivity. Results showed that former NFL players in the AFE <12 group had significantly lower FA in anterior three CC regions and higher radial diffusivity in the most anterior CC region than those in the AFE ≥12 group. This is the first study to find a relationship between AFE to RHI and later-life CC microstructure. These results suggest that incurring RHI during critical periods of CC development may disrupt neurodevelopmental processes, including myelination, resulting in altered CC microstructure.

  7. An integrated multichannel neural recording analog front-end ASIC with area-efficient driven right leg circuit.

    Science.gov (United States)

    Tao Tang; Wang Ling Goh; Lei Yao; Jia Hao Cheong; Yuan Gao

    2017-07-01

    This paper describes an integrated multichannel neural recording analog front end (AFE) with a novel area-efficient driven right leg (DRL) circuit to improve the system common mode rejection ratio (CMRR). The proposed AFE consists of an AC-coupled low-noise programmable-gain amplifier, an area-efficient DRL block and a 10-bit SAR ADC. Compared to conventional DRL circuit, the proposed capacitor-less DRL design achieves 90% chip area reduction with enhanced CMRR performance, making it ideal for multichannel biomedical recording applications. The AFE circuit has been designed in a standard 0.18-μm CMOS process. Post-layout simulation results show that the AFE provides two gain settings of 54dB/60dB while consuming 1 μA per channel under a supply voltage of 1 V. The input-referred noise of the AFE integrated from 1 Hz to 10k Hz is only 4 μVrms and the CMRR is 110 dB.

  8. Definite existence of subphases with eight- and ten-layer unit cells as studied by complementary methods, electric-field-induced birefringence and microbeam resonant x-ray scattering.

    Science.gov (United States)

    Feng, Zhengyu; Chandani Perera, A D L; Fukuda, Atsuo; Vij, Jagdish K; Ishikawa, Ken; Iida, Atsuo; Takanishi, Yoichi

    2017-07-01

    A mixture of two selenium-containing compounds, 80 wt. % AS657 and 20 wt. % AS620, are studied with two complementary methods, electric-field-induced birefringence (EFIB) and microbeam resonant x-ray scattering (μRXS). The mixture shows the typical phase sequence of Sm-C_{A}^{*}-1/3-1/2-Sm-C^{*}-Sm-C_{α}^{*}-Sm-A, where 1/3 and 1/2 are two prototypal ferrielectric and antiferroelectric subphases with three- and four-layer unit cells, respectively. Here we designate the subphase as its q_{T} number defined by the ratio of [F]/([F]+[A]), where [F] and [A] are the numbers of synclinic ferroelectric and anticlinic antiferroelectric orderings in the unit cell, respectively. The electric field vs temperature phase diagram with EFIB contours indicates the emergence of three additional subphases, an antiferroelectric one between Sm-C_{A}^{*} and 1/3 and antiferroelectric and apparently ferrielectric ones between 1/3 and 1/2. The simplest probable q_{T}'s for these additional subphases are 1/4, 2/5, and 3/7, respectively, in the order of increasing temperature. The μRXS profiles indicate that antiferroelectric 1/4 and 2/5 approximately have the eight-layer (FAAAFAAA) and ten-layer (FAFAAFAFAA) Ising unit cells, respectively. The remaining subphase may be ferrielectric 3/7 with a seven-layer unit cell, although the evidence is partial. These experimental results are compared with the phenomenological Landau model [P. V. Dolganov and E. I. Kats, Liq. Cryst. Rev. 1, 127 (2014)2168-039610.1080/21680396.2013.869667] and the quasimolecular model [A. V. Emelyanenko and M. A. Osipov, Phys. Rev. E 68, 051703 (2003)1063-651X10.1103/PhysRevE.68.051703].

  9. Pyroelectric and dielectric energy conversion – A new view of the old problem

    International Nuclear Information System (INIS)

    Poprawski, W.; Gnutek, Z.; Radojewski, J.; Poprawski, R.

    2015-01-01

    The pyroelectric effect is commonly used to construct infrared radiation detectors. In this article we intend to pay attention to a possibility of the pyroelectric effect employment along with the temperature dependence of the dielectric permittivity into a direct conversion of the time-alternating heat flux and the electromagnetic radiation to the electric energy. Converters making use of the mentioned phenomena can be applied in the low-power electric energy generators mounted in autonomous electronic devices. Operation principles for pyroelectric and dielectric generators (PEG and DEG) of the electric energy are presented in this work together with a brief review on ferro- and antiferroelectric materials suitable for the generators. It was shown that for the ferroelectrics with the second-order phase transition the conversion efficiency of PEGs did not depend on temperature in a wide temperature range, and ferroelectrics showing an order–disorder phase transition together with composites and heterostructures based on these ferroelectrics had high conversion efficiency. For the first time ferro- and antiferroelectric materials were extensively reviewed with regard to their applicability in PEGs. It was also shown that ferro- and antiferroelectrics with translation-type phase transition, quantum ferroelectrics, ferro- and antiferroelectric relaxors were good materials for DEGs. Considering literature data the efficiency for the thermal-to-electrical energy conversion was estimated for a few typical material groups. Advantages and disadvantages of the individual groups were presented along with their possible limitations for PEG and DEG usage. - Highlights: • A direct conversion of the alternating heat flux to the electric energy is described. • Order–disorder-type ferroelectrics were found to be suitable for pyroelectric energy generators. • Certain ferro- and antiferroelectrics, quantum ones and relaxors were good for dielectric converters. • The

  10. Signal Digitizer and Cross-Correlation Application Specific Integrated Circuit

    Science.gov (United States)

    Baranauskas, Dalius (Inventor); Baranauskas, Gytis (Inventor); Zelenin, Denis (Inventor); Kangaslahti, Pekka (Inventor); Tanner, Alan B. (Inventor); Lim, Boon H. (Inventor)

    2017-01-01

    According to one embodiment, a cross-correlator comprises a plurality of analog front ends (AFEs), a cross-correlation circuit and a data serializer. Each of the AFEs comprises a variable gain amplifier (VGA) and a corresponding analog-to-digital converter (ADC) in which the VGA receives and modifies a unique analog signal associates with a measured analog radio frequency (RF) signal and the ADC produces digital data associated with the modified analog signal. Communicatively coupled to the AFEs, the cross-correlation circuit performs a cross-correlation operation on the digital data produced from different measured analog RF signals. The data serializer is communicatively coupled to the summing and cross-correlating matrix and continuously outputs a prescribed amount of the correlated digital data.

  11. Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes

    Science.gov (United States)

    Alosco, M L; Kasimis, A B; Stamm, J M; Chua, A S; Baugh, C M; Daneshvar, D H; Robbins, C A; Mariani, M; Hayden, J; Conneely, S; Au, R; Torres, A; McClean, M D; McKee, A C; Cantu, R C; Mez, J; Nowinski, C J; Martin, B M; Chaisson, C E; Tripodis, Y; Stern, R A

    2017-01-01

    Previous research suggests that age of first exposure (AFE) to football before age 12 may have long-term clinical implications; however, this relationship has only been examined in small samples of former professional football players. We examined the association between AFE to football and behavior, mood and cognition in a large cohort of former amateur and professional football players. The sample included 214 former football players without other contact sport history. Participants completed the Brief Test of Adult Cognition by Telephone (BTACT), and self-reported measures of executive function and behavioral regulation (Behavior Rating Inventory of Executive Function-Adult Version Metacognition Index (MI), Behavioral Regulation Index (BRI)), depression (Center for Epidemiologic Studies Depression Scale (CES-D)) and apathy (Apathy Evaluation Scale (AES)). Outcomes were continuous and dichotomized as clinically impaired. AFE was dichotomized into football before age 12 corresponded with >2 × increased odds for clinically impaired scores on all measures but BTACT: (odds ratio (OR), 95% confidence interval (CI): BRI, 2.16,1.19–3.91; MI, 2.10,1.17–3.76; CES-D, 3.08,1.65–5.76; AES, 2.39,1.32–4.32). Younger AFE predicted increased odds for clinical impairment on the AES (OR, 95% CI: 0.86, 0.76–0.97) and CES-D (OR, 95% CI: 0.85, 0.74–0.97). There was no interaction between AFE and highest level of play. Younger AFE to football, before age 12 in particular, was associated with increased odds for impairment in self-reported neuropsychiatric and executive function in 214 former American football players. Longitudinal studies will inform youth football policy and safety decisions. PMID:28926003

  12. Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes.

    Science.gov (United States)

    Alosco, M L; Kasimis, A B; Stamm, J M; Chua, A S; Baugh, C M; Daneshvar, D H; Robbins, C A; Mariani, M; Hayden, J; Conneely, S; Au, R; Torres, A; McClean, M D; McKee, A C; Cantu, R C; Mez, J; Nowinski, C J; Martin, B M; Chaisson, C E; Tripodis, Y; Stern, R A

    2017-09-19

    Previous research suggests that age of first exposure (AFE) to football before age 12 may have long-term clinical implications; however, this relationship has only been examined in small samples of former professional football players. We examined the association between AFE to football and behavior, mood and cognition in a large cohort of former amateur and professional football players. The sample included 214 former football players without other contact sport history. Participants completed the Brief Test of Adult Cognition by Telephone (BTACT), and self-reported measures of executive function and behavioral regulation (Behavior Rating Inventory of Executive Function-Adult Version Metacognition Index (MI), Behavioral Regulation Index (BRI)), depression (Center for Epidemiologic Studies Depression Scale (CES-D)) and apathy (Apathy Evaluation Scale (AES)). Outcomes were continuous and dichotomized as clinically impaired. AFE was dichotomized into football before age 12 corresponded with >2 × increased odds for clinically impaired scores on all measures but BTACT: (odds ratio (OR), 95% confidence interval (CI): BRI, 2.16,1.19-3.91; MI, 2.10,1.17-3.76; CES-D, 3.08,1.65-5.76; AES, 2.39,1.32-4.32). Younger AFE predicted increased odds for clinical impairment on the AES (OR, 95% CI: 0.86, 0.76-0.97) and CES-D (OR, 95% CI: 0.85, 0.74-0.97). There was no interaction between AFE and highest level of play. Younger AFE to football, before age 12 in particular, was associated with increased odds for impairment in self-reported neuropsychiatric and executive function in 214 former American football players. Longitudinal studies will inform youth football policy and safety decisions.

  13. A 16-Channel CMOS Chopper-Stabilized Analog Front-End ECoG Acquisition Circuit for a Closed-Loop Epileptic Seizure Control System.

    Science.gov (United States)

    Wu, Chung-Yu; Cheng, Cheng-Hsiang; Chen, Zhi-Xin

    2018-06-01

    In this paper, a 16-channel analog front-end (AFE) electrocorticography signal acquisition circuit for a closed-loop seizure control system is presented. It is composed of 16 input protection circuits, 16 auto-reset chopper-stabilized capacitive-coupled instrumentation amplifiers (AR-CSCCIA) with bandpass filters, 16 programmable transconductance gain amplifiers, a multiplexer, a transimpedance amplifier, and a 128-kS/s 10-bit delta-modulated successive-approximation-register analog-to-digital converter (SAR ADC). In closed-loop seizure control system applications, the stimulator shares the same electrode with the AFE amplifier for effective suppression of epileptic seizures. To prevent from overstress in MOS devices caused by high stimulation voltage, an input protection circuit with a high-voltage-tolerant switch is proposed for the AFE amplifier. Moreover, low input-referred noise is achieved by using the chopper modulation technique in the AR-CSCCIA. To reduce the undesired effects of chopper modulation, an improved offset reduction loop is proposed to reduce the output offset generated by input chopper mismatches. The digital ripple reduction loop is also used to reduce the chopper ripple. The fabricated AFE amplifier has 49.1-/59.4-/67.9-dB programmable gain and 2.02-μVrms input referred noise in a bandwidth of 0.59-117 Hz. The measured power consumption of the AFE amplifier is 3.26 μW per channel, and the noise efficiency factor is 3.36. The in vivo animal test has been successfully performed to verify the functions. It is shown that the proposed AFE acquisition circuit is suitable for implantable closed-loop seizure control systems.

  14. Effects of alfalfa flavonoids extract on the microbial flora of dairy cow rumen.

    Science.gov (United States)

    Zhan, Jinshun; Liu, Mingmei; Wu, Caixia; Su, Xiaoshuang; Zhan, Kang; Zhao, Guo Qi

    2017-09-01

    The effect of flavonoids from alfalfa on the microbial flora was determined using molecular techniques of 16S ribosome deoxyribonucleic acid (rDNA) analysis. Four primiparous Holstein heifers fitted with ruminal cannulas were used in a 4×4 Latin square design and fed a total mixed ration to which alfalfa flavonoids extract (AFE) was added at the rates of 0 (A, control), 20 (B), 60 (C), or 100 (D) mg per kg of heifer BW. The number of operational taxonomic units in heifers given higher levels of flavonoid extract (C and D) was higher than for the two other treatments. The Shannon, Ace, and Chao indices for treatment C were significantly higher than for the other treatments (pflora for the four treatments. The microbial flora in treatment A was similar to that in B, C, and D were similar by the weighted analysis. The richness of Tenericutes at the phylum level tended to increase with increasing AFE (p = 0.10). The proportion of Euryarchaeota at the phylum level increased linearly, whereas the proportion of Fusobacteria decreased linearly with increasing AFE supplementation (p = 0.04). The percentage of Mogibacterium , Pyramidobacter , and Asteroleplasma at the genus level decreased linearly with increasing AFE (p<0.05). The abundance of Spirochaeta , Succinivibrio , and Suttonella at the genus level tended to decrease linearly with increasing AFE (0.05AFE in the diet of dairy cows may alter the microbial composition of the rumen; however its effect on nutrient digestibility remains to be determined.

  15. THE ACTIVE FAULTS OF EURASIA DATABASE

    Directory of Open Access Journals (Sweden)

    D. M. Bachmanov

    2017-01-01

    Full Text Available This paper describes the technique used to create and maintain the Active Faults of Eurasia Database (AFED based on the uniform format that ensures integrating the materials accumulated by many researchers, inclu­ding the authors of the AFED. The AFED includes the data on more than 20 thousand objects: faults, fault zones and associated structural forms that show the signs of latest displacements in the Late Pleistocene and Holocene. The geographical coordinates are given for each object. The AFED scale is 1:500000; the demonstration scale is 1:1000000. For each object, the AFED shows two kinds of characteristics: justification attributes, and estimated attributes. The justification attributes inform the AFED user about an object: the object’s name; morphology; kinematics; the amplitudes of displacement for different periods of time; displacement rates estimated from the amplitudes; the age of the latest recorded signs of activity, seismicity and paleoseismicity; the relationship of the given objects with the parameters of crustal earthquakes; etc. The sources of information are listed in the AFED appendix. The estimated attributes are represented by the system of indices reflecting the fault kinematics according to the classification of the faults by types, as accepted in structural geology, and includes three ranks of the Late Quaternary movements and four degrees of reliability of identifying the structures as active ones. With reference to the indices, the objects can be compared with each other, considering any of the attributes, or with any other digitized information. The comparison can be performed by any GIS software. The AFED is an efficient tool for obtaining the information on the faults and solving general problems, such as thematic mapping, determining the parameters of modern geodynamic processes, estima­ting seismic and other geodynamic hazards, identifying the tectonic development trends in the Pliocene–Quaternary stage of

  16. Emergent Social Software Platforms for the Sharing of and Collaboration on Criminal Information and Intelligence

    Science.gov (United States)

    2012-09-01

    Next Wave of Knowledge Worker Productivity, Oracle, 2008), 6. 80 Andrew McAfee, “Shattering the Myths about Enterprise 2.0,” Harvard Business...Organizations,” Electronic Library, the 27, no. 6 (2009), 906, 911. 82 Andrew McAfee, Shattering the Myths about Enterprise 2.0, 2. 83 Don Tapscott and...the Web Director for NASA’s Goddard Space Center, “You’re supposed to let anyone talk to anyone else, and that can be a little scary for

  17. Compact Front-end Prototype for Next Generation RFI-rejecting Polarimetric L-band Radiometer

    DEFF Research Database (Denmark)

    Jensen, Brian Sveistrup; Søbjærg, Sten Schmidl; Skou, Niels

    2009-01-01

    Realizing the need for lower noise figure and smaller physical size in todays higly sensitive radiometers, this paper presents a new compact analog front-end (AFE) for use with the existing L-band (1400-1427 MHz) radiometer designed and operated by the Technical University of Denmark. Using subha...

  18. Awareness and Use of Social Bookmarking Services by Final Year ...

    African Journals Online (AJOL)

    The Web is now more interactive than ever before. So many ... To assess the use of social bookmarking services by the final year students of Afe .... Delicious, developed in 2003 is perhaps the best known currently of all such tools (Lund et al,.

  19. Bioinformatic Prediction of Gene Functions Regulated by Quorum Sensing in the Bioleaching Bacterium Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    Alvaro Banderas

    2013-08-01

    Full Text Available The biomining bacterium Acidithiobacillus ferrooxidans oxidizes sulfide ores and promotes metal solubilization. The efficiency of this process depends on the attachment of cells to surfaces, a process regulated by quorum sensing (QS cell-to-cell signalling in many Gram-negative bacteria. At. ferrooxidans has a functional QS system and the presence of AHLs enhances its attachment to pyrite. However, direct targets of the QS transcription factor AfeR remain unknown. In this study, a bioinformatic approach was used to infer possible AfeR direct targets based on the particular palindromic features of the AfeR binding site. A set of Hidden Markov Models designed to maintain palindromic regions and vary non-palindromic regions was used to screen for putative binding sites. By annotating the context of each predicted binding site (PBS, we classified them according to their positional coherence relative to other putative genomic structures such as start codons, RNA polymerase promoter elements and intergenic regions. We further used the Multiple EM for Motif Elicitation algorithm (MEME to further filter out low homology PBSs. In summary, 75 target-genes were identified, 34 of which have a higher confidence level. Among the identified genes, we found afeR itself, zwf, genes encoding glycosyltransferase activities, metallo-beta lactamases, and active transport-related proteins. Glycosyltransferases and Zwf (Glucose 6-phosphate-1-dehydrogenase might be directly involved in polysaccharide biosynthesis and attachment to minerals by At. ferrooxidans cells during the bioleaching process.

  20. Bioinformatic Prediction of Gene Functions Regulated by Quorum Sensing in the Bioleaching Bacterium Acidithiobacillus ferrooxidans

    Science.gov (United States)

    Banderas, Alvaro; Guiliani, Nicolas

    2013-01-01

    The biomining bacterium Acidithiobacillus ferrooxidans oxidizes sulfide ores and promotes metal solubilization. The efficiency of this process depends on the attachment of cells to surfaces, a process regulated by quorum sensing (QS) cell-to-cell signalling in many Gram-negative bacteria. At. ferrooxidans has a functional QS system and the presence of AHLs enhances its attachment to pyrite. However, direct targets of the QS transcription factor AfeR remain unknown. In this study, a bioinformatic approach was used to infer possible AfeR direct targets based on the particular palindromic features of the AfeR binding site. A set of Hidden Markov Models designed to maintain palindromic regions and vary non-palindromic regions was used to screen for putative binding sites. By annotating the context of each predicted binding site (PBS), we classified them according to their positional coherence relative to other putative genomic structures such as start codons, RNA polymerase promoter elements and intergenic regions. We further used the Multiple EM for Motif Elicitation algorithm (MEME) to further filter out low homology PBSs. In summary, 75 target-genes were identified, 34 of which have a higher confidence level. Among the identified genes, we found afeR itself, zwf, genes encoding glycosyltransferase activities, metallo-beta lactamases, and active transport-related proteins. Glycosyltransferases and Zwf (Glucose 6-phosphate-1-dehydrogenase) might be directly involved in polysaccharide biosynthesis and attachment to minerals by At. ferrooxidans cells during the bioleaching process. PMID:23959118

  1. Texas Tech & University of Arizona Win APPA's 2013 Award for Excellence

    Science.gov (United States)

    Clendenning, Joanie; Kopach, Christopher M.

    2013-01-01

    APPA's highest institutional honor, the "Award for Excellence in Facilities Management (AFE)," recognizes those educational institutions whose facilities management organizations demonstrate quality in overall operations and effectiveness. The Award for Excellence is based on a set of criteria that include: Leadership; Strategic and…

  2. The Impact of Balance of Payment Considerations Upon Logistical Support of U.S. Armed Forces Europe 1960-1974

    Science.gov (United States)

    1974-01-01

    AFE Form 1 lp must attest to the validity of the requirement and confirm that the required service(s) (i) cannot physically be returned to the U.s. ror...Material Allaire, Christopher J. "How Can We Offset the Costs of U.S. Forces in the Federal Republic of Germay." Monograph, Army War Collge , 1973

  3. AN EXAMINATION OF CONTEMPORARY ISSUES RELATING TO ...

    African Journals Online (AJOL)

    In Nigeria, cases of negligence are under-reported; consequently mar- ... and Business Law, College of Law, Afe Babalola University Ado-Ekiti, Ekiti, Nigeria. ...... 55 See Grubb [1988] C LJ 12, Contrast Jones, Textbook on Torts (3rd ed) 113 – 4. .... 'Consent for Anaesthesia' (2004) 30 Journal of Medical Ethics 286–290.

  4. Tips From Former Smokers – 2013 Campaign

    Centers for Disease Control (CDC) Podcasts

    Tim McAfee, MD, MPH, of CDC’s Office on Smoking and Health, discusses the 2013 Tips campaign, and his personal experience as a doctor treating people with diseases caused by smoking, or made worse by it. He also offers advice on how people can quit smoking.

  5. A Survey of Advertising Awareness and Enlistment Planning by Recent Enlistees in the Armed Services

    Science.gov (United States)

    of recent advertising and recruiting, planning patterns of enlistees, and possible advertising strategies . (Author)...A sample of recent enlistees for all the services was interviewed at four AFEES centers. Questions were asked about awareness of advertising and the...planning for their recent enlistment decision. Advertising awareness included specific copy point recall, slogan identification, believability of

  6. Development and Testing of an Ultra Low Power System-On-Chip (SOC) Platform for Marine Mammal Tags and Passive Acoustic Signal Processing

    Science.gov (United States)

    2014-09-30

    and testing convenience. The AFE chip includes the analog front end interfaces to both the depth sensor ( piezo sensor) and the hydrophone. The...output signal in the high-gain mode is saturated even with the minimum input level of 150µV. Thus, we use a resistor voltage divider at the input to

  7. Wireless biopotential acquisition system for portable healthcare monitoring.

    Science.gov (United States)

    Wang, W-S; Huang, H-Y; Wu, Z-C; Chen, S-C; Wang, W-F; Wu, C-F; Luo, C-H

    2011-07-01

    A complete biopotential acquisition system with an analogue front-end (AFE) chip is proposed for portable healthcare monitoring. A graphical user interface (GUI) is also implemented to display the extracted biopotential signals in real-time on a computer for patients or in a hospital via the internet for doctors. The AFE circuit defines the quality of the acquired biosignals. Thus, an AFE chip with low power consumption and a high common-mode rejection ratio (CMRR) was implemented in the TSMC 0.18-μm CMOS process. The measurement results show that the proposed AFE, with a core area of 0.1 mm(2), has a CMRR of 90 dB, and power consumption of 21.6 μW. Biopotential signals of electroencephalogram (EEG), electrocardiogram (ECG) and electromyogram (EMG) were measured to verify the proposed system. The board size of the proposed system is 6 cm × 2.5 cm and the weight is 30 g. The total power consumption of the proposed system is 66 mW. Copyright © 2011 Informa UK, Ltd.

  8. THE NEED TO FLUSH OUT MISCREANTS FROM THE NIGERIAN ...

    African Journals Online (AJOL)

    conference this year at the College of Law, Afe Babalola University Ado ... Paper presented at the 48th Annual Conference of the Nigerian Association of Law ..... be trained in law, but must also be trained in related fields such as business,.

  9. The CUBLAS and CULA based GPU acceleration of adaptive finite element framework for bioluminescence tomography.

    Science.gov (United States)

    Zhang, Bo; Yang, Xiang; Yang, Fei; Yang, Xin; Qin, Chenghu; Han, Dong; Ma, Xibo; Liu, Kai; Tian, Jie

    2010-09-13

    In molecular imaging (MI), especially the optical molecular imaging, bioluminescence tomography (BLT) emerges as an effective imaging modality for small animal imaging. The finite element methods (FEMs), especially the adaptive finite element (AFE) framework, play an important role in BLT. The processing speed of the FEMs and the AFE framework still needs to be improved, although the multi-thread CPU technology and the multi CPU technology have already been applied. In this paper, we for the first time introduce a new kind of acceleration technology to accelerate the AFE framework for BLT, using the graphics processing unit (GPU). Besides the processing speed, the GPU technology can get a balance between the cost and performance. The CUBLAS and CULA are two main important and powerful libraries for programming on NVIDIA GPUs. With the help of CUBLAS and CULA, it is easy to code on NVIDIA GPU and there is no need to worry about the details about the hardware environment of a specific GPU. The numerical experiments are designed to show the necessity, effect and application of the proposed CUBLAS and CULA based GPU acceleration. From the results of the experiments, we can reach the conclusion that the proposed CUBLAS and CULA based GPU acceleration method can improve the processing speed of the AFE framework very much while getting a balance between cost and performance.

  10. GPR utilization in artificial freezing engineering

    International Nuclear Information System (INIS)

    Song, Lei; Yang, Weihao; Huang, Jiahui; Li, Haipeng; Zhang, Xiaojun

    2013-01-01

    To utilize ground penetrating radar (GPR) in artificial freezing engineering (AFE), the electromagnetic parameters (EMP) of frozen soil were measured using a vector network analyser, which showed that the dielectric permittivity and electric conductivity change abruptly at the boundary between the frozen and the non-frozen soil. Then similarity criteria of GPR model experiments were deduced, and GPR laboratory model experiments and field explorations of AFE were carried out. It was found that for AFE, the GPR travel time and profile characters of anomalies in model experiments were similar to those in field explorations, while the amplitude of GPR signals in laboratory model experiments were much stronger than those in field explorations. Numerical simulations were also implemented to analyse the relationship between model experiments and field explorations, which further told us why we could easily find the targets by GPR in the laboratory but not in field explorations. The outputs showed that GPR could be used to detect the thickness of the frozen wall and to find unfrozen soil defects, even though the amplitude of the reflective signals were much weaker than those of laboratory experiments. The research findings have an important theoretical value for AFE and permafrost region engineering, and the deduced GPR similarity criteria could be widely used in other GPR model experiments. (paper)

  11. Coding interview questions concepts, problems, interview questions

    CERN Document Server

    Karumanchi, Narasimha

    2016-01-01

    Peeling Data Structures and Algorithms: * Programming puzzles for interviews * Campus Preparation * Degree/Masters Course Preparation * Instructor’s * GATE Preparation * Big job hunters: Microsoft, Google, Amazon, Yahoo, Flip Kart, Adobe, IBM Labs, Citrix, Mentor Graphics, NetApp, Oracle, Webaroo, De-Shaw, Success Factors, Face book, McAfee and many more * Reference Manual for working people

  12. Competing Auctions of Skills

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Christian Daniel

    The model of competing sellers McAfee (1993) is applied to a labor market environment with heterogeneous workers, who differ by outside option and skill type, and heterogeneous firms, who differ by the amount of output produced when matched to each possible worker tyoe. We derive both a static...

  13. Atypical Amniotic Fluid Embolism Managed with a Novel Therapeutic Regimen

    Directory of Open Access Journals (Sweden)

    Shadi Rezai

    2017-01-01

    Full Text Available Amniotic fluid embolism (AFE is the second leading cause of maternal mortality in the USA with an incidence of 1 : 15,200 births. The case fatality rate and perinatal mortality associated with AFE are 13–30% and 9–44%, respectively. This rare but devastating complication can be difficult to diagnose as many of the early signs and symptoms are nonspecific. Compounding this diagnostic challenge is a lack of effective treatment regimens which to date are mostly supportive. We present the case of a 26-year-old woman who suffered from suspected AFE and was successfully treated with the novel regimen of Atropine, Ondansetron, and Ketorolac (A-OK. The authors acknowledge that this case does not meet the new criteria proposed, by Clark in 2016, but feel that it is important to share this case report, due to dramatic patient response to the provided supportive therapy presented in this case report. We hope this case report will prompt further research into this novel approach to treating AFE with Atropine, Ondansetron, and Ketorolac.

  14. Defense.gov Special Report: Women's History Month 2013

    Science.gov (United States)

    Hall. Profile Army Maj. Gen. Marcia M. Anderson Profile Photo: Navy Capt. Mildred H. McAfee Army Maj took on roles as spies. Representation of the U.S. Frigate United States, Stephen Decatur Esqr nurses aboard Commodore Stephen Decatur's ship, the United States. Dr. Mary Edwards Walker wearing her

  15. Iron sulphide containing hydrodesulfurization catalysts : Mössbauer study of the sulfidibility of alpha-iron(III) oxide

    NARCIS (Netherlands)

    Ramselaar, W.L.T.M.; Beer, de V.H.J.; Kraan, van der A.M.

    1988-01-01

    As a first step in the study of the sulphidation of carbon-supported iron oxide catalyst systems the sulphiding of a well-characterized, unsupported model compound, viz. a-Fe2O3(mean particle diameter ca. 50 nm) was investigated using in-situ Mössbauer spectroscopy and the temperature-programmed

  16. Enhancing Research in Networking & System Security, and Forensics, in Puerto Rico

    Science.gov (United States)

    2015-03-03

    Conference 2014 – Seattle, WA – Travel Scholarship awarded by Google. Celedonio was able to meet Mr. Tony Baylis, a recruiter from the Lawrence...Microsoft, Encase, Avaya, McAfee, Cisco , Department of Homeland Security, Department of Defense, ISACA among others. International Conferences in

  17. REALIZING THE RIGHT TO DEVELOPMENT IN NIGERIA: AN ...

    African Journals Online (AJOL)

    RAYAN_

    Lecturer, Department of Public and International Law, College of Law, Afe. Babalola ... in the conditions of life of people in that particular area, as there cannot be said to be ... and contribute to national development.9 Development is a continuous ... to the challenges faced by developing countries, specifically Nigeria, in.

  18. Ferroelectricity in high-density H{sub 2}O ice

    Energy Technology Data Exchange (ETDEWEB)

    Caracas, Razvan, E-mail: razvan.caracas@ens-lyon.fr, E-mail: rhemley@ciw.edu [CNRS, Laboratoire de Géologie de Lyon UMR5276, Ecole Normale Supérieure de Lyon, 46, alleé d’Italie, Université Claude-Bernard Lyon 1, Université de Lyon, 69364 Lyon cedex 07 (France); Hemley, Russell J., E-mail: razvan.caracas@ens-lyon.fr, E-mail: rhemley@ciw.edu [Geophysical Laboratory, 5251 Broad Branch Road NW, Carnegie Institution of Washington, Washington, DC 20015 (United States)

    2015-04-07

    The origin of longstanding anomalies in experimental studies of the dense solid phases of H{sub 2}O ices VII, VIII, and X is examined using a combination of first-principles theoretical methods. We find that a ferroelectric variant of ice VIII is energetically competitive with the established antiferroelectric form under pressure. The existence of domains of the ferroelectric form within anti-ferroelectric ice can explain previously observed splittings in x-ray diffraction data. The ferroelectric form is stabilized by density and is accompanied by the onset of spontaneous polarization. The presence of local electric fields triggers the preferential parallel orientation of the water molecules in the structure, which could be stabilized in bulk using new high-pressure techniques.

  19. A theory of piezoelectric, elastic, and dielectric properties of the KH2PO4 family crystals under the strain u6. Phase transition and the piezoelectric effect in the KH2PO4 crystal

    International Nuclear Information System (INIS)

    Levits'kij, R.R.; Lyisnij, B.M.

    2003-01-01

    In order to study the dielectric, piezoelectric and elastic properties of ferroelectrics and antiferroelectrics of the KH 2 PO 4 family, we consider an extended proton tunneling model that takes into account the shear strain u 6 . In the four-particle cluster approximation for the short-range interactions and the mean field approximation for the long-range interaction we calculate the transverse components of the dielectric susceptibility tensor of the KH 2 PO 4 family ferroelectrics

  20. Novel liquid crystals based on [1] benzothieno [3,2-b][1] benzopthiophene

    Czech Academy of Sciences Publication Activity Database

    Košata, B.; Kozmik, V.; Svoboda, J.; Novotná, Vladimíra; Vaněk, Přemysl; Glogarová, Milada

    2003-01-01

    Roč. 30, č. 5 (2003), s. 603-610 ISSN 0267-8292 R&D Projects: GA ČR GA106/00/0580; GA ČR GA202/02/0840 Institutional research plan: CEZ:AV0Z1010914 Keywords : antiferroelectric phase * dielectric fused spectroscopy * heterocyclic compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.158, year: 2003

  1. Entropy-Stabilized Oxides

    Science.gov (United States)

    2015-09-29

    antiferroelectrics. Phys. Rev. Lett. 110, 017603 (2013). 22. Cantor , B., Chang, I., Knight, P. & Vincent, A. Microstructural development in equiatomic...Science 345, 1153–1158 (2014). 24. Gali, A. & George , E. Tensile properties of high- and medium-entropy alloys. Intermetallics 39, 74–78 (2013). 25...148–153 (2014). 26. Otto, F., Yang, Y., Bei, H. & George , E. Relative effects of enthalpy and entropy on the phase stability of equiatomic high-entropy

  2. Ultra-broad-band dielectric spectroscopy and phonons in (Pb.sub.1-x/2./sub.La.sub.x./sub.)(Zr.sub.0.9./sub.Ti.sub.0.1./sub.)O.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Buixaderas, Elena; Bovtun, Viktor; Veljko, Sergiy; Savinov, Maxim; Kužel, Petr; Gregora, Ivan; Kamba, Stanislav; Reaney, I.

    2010-01-01

    Roč. 108, č. 10 (2010), 104101/1-104101/10 ISSN 0021-8979 R&D Projects: GA AV ČR KAN301370701; GA ČR GAP204/10/0616 Institutional research plan: CEZ:AV0Z10100520 Keywords : PLZT * phase transitions * Raman and IR spectroscopy * ferro-antiferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.064, year: 2010

  3. Effect of multilactate chiral part of liquid crystalline molecule on mesomorphic behaviour

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej M.; Novotná, Vladimíra; Hamplová, Věra; Kašpar, Miroslav; Glogarová, Milada

    2008-01-01

    Roč. 892, 1-3 (2008), 151-157 ISSN 0022-2860 R&D Projects: GA MŠk OC 175; GA AV ČR IAA100100710 Institutional research plan: CEZ:AV0Z10100520 Keywords : lactic acid derivative * liquid crystal * ferroelectric liquid crystal * antiferroelectric phase * hexatic phase * keto group * lactate group Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.594, year: 2008

  4. Dipolar phases in liquid crystals with the chiral part based on the lactic acid

    Czech Academy of Sciences Publication Activity Database

    Glogarová, Milada; Novotná, Vladimíra; Kašpar, Miroslav; Hamplová, Věra; Pociecha, D.

    2008-01-01

    Roč. 81, 11-12 (2008), 963-970 ISSN 0141-1594 R&D Projects: GA MŠk OC 175; GA AV ČR IAA100100710 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * paraelectric * ferroelectric and antiferroelectric phases * TGB phases * lactate unit Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.201, year: 2008

  5. Prehistory effect on dielectric properties of NaNbO3-Gd1/3NbO3

    International Nuclear Information System (INIS)

    Burkhanov, A.I.; Bondarenko, P.V.; Shil'nikov, A.V.; Raevskaya, S.I.; Raevskij, I.P.

    2006-01-01

    One studied the low- and the infralow-frequency dielectric response of 0.9NaNbO 3 -0.1Gd 1/3 NbO 3 (NNG10) composition ceramics and single crystal at the material different prehistory. One revealed the differences in the nature of dielectric aging in NaNbO 3 antiferroelectric base material with a diffused phase transition in contrast to manifestation of similar phenomena in ferroelectrics-relaxors [ru

  6. Induced phase transformations and nature of metastable states in ZTLL ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ishchuk, V M; Zavadskij, Eh A

    1987-12-01

    Phase transitions in ZTLL ceramics with zirconium content being 65%, titanium content - 35%, are considered. Peculiarities in the ZTLL behaviour are shown to be caused by the existence of an intermediate range between ferroelectric and antiferroelectric states. The state of samples in the range is determined by their prehistory. It is emphasized that phase transitions in ZTLL can be explained in the framework of the existing models.

  7. F centers emission in KCN

    International Nuclear Information System (INIS)

    Ohkura, H.; Carmo, L.C.S. do; Kalinowski, H.J.; Ribeiro, S.C.

    1976-01-01

    The emission spectrum of F centers in KCN is reported. The temperature dependence of this emission between 62 K and 178K was measured and the energy gap between the relaxed excited state and conduction band could be determined as 070 eV. Below the antiferroelectric transition temperature at 83K a blue shift in the peak of the emission spectrum is observed due partially to the internal Stark effect

  8. Insights into the Quorum Sensing Regulon of the Acidophilic Acidithiobacillus ferrooxidans Revealed by Transcriptomic in the Presence of an Acyl Homoserine Lactone Superagonist Analogue

    Directory of Open Access Journals (Sweden)

    Sigde Mamani

    2016-09-01

    Full Text Available While a functional quorum sensing system has been identified in the acidophilic chemolithoautotroph Acidithiobacillus ferrooxidans ATCC 23270T and shown to modulate cell adhesion to solid substrates, nothing is known about the genes it regulates. To address the question of how quorum sensing controls biofilm formation in At. ferrooxidansT, the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic superagonist AHL analogue has been studied. First, the effect on biofilm formation of a synthetic AHL tetrazolic analogue, tetrazole 9c, known for its agonistic QS activity, was assessed by fluorescence and electron microscopy experiments. A faster adherence of At. ferrooxidansT cells on sulfur coupons was observed. Then, tetrazole 9c was used in DNA microarray experiments that allowed the identification of genes regulated by quorum sensing signalling, and more particularly, those involved in early biofilm formation. Interestingly, afeI gene, encoding the AHL synthase, but not the At. ferrooxidans quorum sensing transcriptional regulator AfeR encoding gene, was shown to be regulated by quorum sensing. Data indicated that QS network represents at least 4.5 % (141 genes of the ATCC 23270T genome of which 42.5 % (60 genes are related to biofilm formation. Finally, AfeR was shown to bind specifically to the regulatory region of the afeI gene at the level of the palindromic sequence predicted to be the AfeR binding site. Our results give new insights on the response of At. ferrooxidans to quorum sensing and on biofilm biogenesis, opening new biological/chemical alternatives for bioleaching development and managing acid Mine/Rock drainage environmental damages.

  9. Pressure, temperature, and electric field dependence of phase transformations in niobium modified 95/5 lead zirconate titanate

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Wen D.; Carlos Valadez, J.; Gallagher, John A.; Jo, Hwan R.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, The University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095 (United States); Sahul, Raffi; Hackenberger, Wes [TRS Technologies, 2820 East College Avenue, State College, Pennsylvania 16801 (United States)

    2015-06-28

    Ceramic niobium modified 95/5 lead zirconate-lead titanate (PZT) undergoes a pressure induced ferroelectric to antiferroelectric phase transformation accompanied by an elimination of polarization and a volume reduction. Electric field and temperature drive the reverse transformation from the antiferroelectric to ferroelectric phase. The phase transformation was monitored under pressure, temperature, and electric field loading. Pressures and temperatures were varied in discrete steps from 0 MPa to 500 MPa and 25 °C to 125 °C, respectively. Cyclic bipolar electric fields were applied with peak amplitudes of up to 6 MV m{sup −1} at each pressure and temperature combination. The resulting electric displacement–electric field hysteresis loops were open “D” shaped at low pressure, characteristic of soft ferroelectric PZT. Just below the phase transformation pressure, the hysteresis loops took on an “S” shape, which split into a double hysteresis loop just above the phase transformation pressure. Far above the phase transformation pressure, when the applied electric field is insufficient to drive an antiferroelectric to ferroelectric phase transformation, the hysteresis loops collapse to linear dielectric behavior. Phase stability maps were generated from the experimental data at each of the temperature steps and used to form a three dimensional pressure–temperature–electric field phase diagram.

  10. Heat-Assisted Multiferroic Solid-State Memory.

    Science.gov (United States)

    Lepadatu, Serban; Vopson, Melvin M

    2017-08-25

    A heat-assisted multiferroic solid-state memory design is proposed and analysed, based on a PbNbZrSnTiO₃ antiferroelectric layer and Ni 81 Fe 19 magnetic free layer. Information is stored as magnetisation direction in the free layer of a magnetic tunnel junction element. The bit writing process is contactless and relies on triggering thermally activated magnetisation switching of the free layer towards a strain-induced anisotropy easy axis. A stress is generated using the antiferroelectric layer by voltage-induced antiferroelectric to ferroelectric phase change, and this is transmitted to the magnetic free layer by strain-mediated coupling. The thermally activated strain-induced magnetisation switching is analysed here using a three-dimensional, temperature-dependent magnetisation dynamics model, based on simultaneous evaluation of the stochastic Landau-Lifshitz-Bloch equation and heat flow equation, together with stochastic thermal fields and magnetoelastic contributions. The magnetisation switching probability is calculated as a function of stress magnitude and maximum heat pulse temperature. An operating region is identified, where magnetisation switching always occurs, with stress values ranging from 80 to 180 MPa, and maximum temperatures normalised to the Curie temperature ranging from 0.65 to 0.99.

  11. Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

    International Nuclear Information System (INIS)

    Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

    2011-01-01

    The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO 2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

  12. Effect of Two Different Superstrate Layers On Bismuth Titanate (BiT) Array Antennas

    Science.gov (United States)

    Wee, F. H.; Malek, F.; Al-Amani, A. U.; Ghani, Farid

    2014-01-01

    The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz.

  13. Electrical, thermophysical and micromechanical properties of ethylene-vinyl acetate elastomer composites with surface modified BaTiO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xingyi; Xie Liyuan; Jiang Pingkai; Wang Genlin; Liu Fei, E-mail: xyhuang@sjtu.edu.c, E-mail: pkjiang@sjtu.edu.c [Shanghai Key Lab of Electrical Insulation and Thermal Aging, Department of Polymer Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2009-12-21

    In this study, we investigated the influence of the surface modified BaTiO{sub 3} nanoparticles on the electrical, thermophysical and micromechanical properties of ethylene-vinyl acetate (EVM) vulcanizates. Gamma-aminopropyl triethoxysilane was used as a silane coupling agent for the surface treatment of the BaTiO{sub 3} nanoparticles. It was found that the incorporation of surface modified BaTiO{sub 3} nanoparticles into the EVM matrix not only increased the permittivity, thermal conductivity and the mechanical strength but also showed a comparative dielectric loss tangent with pure EVM vulcanizates. In particular, the nanocomposites exhibit relatively high dielectric strength and good ductility even at the loading level of 50 vol%. The improved properties not only originate from the homogeneous dispersion of BaTiO{sub 3} nanoparticles but also should be ascribed to the strong interfacial interaction between the surface modified BaTiO{sub 3} nanoparticles and EVM matrix. We also investigated the dielectric relaxation behaviour of the BaTiO{sub 3} filled EVM nanocomposites by using Jonscher's theory of universal dielectric response.

  14. Pool boiling performance of Novec{sup TM} 649 engineered fluid

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Eric; Buongiorno, Jacopo; McKrell, Thomas [Massachusetts Institute of Technology, Cambridge (United States). Dept. of Nuclear Science and Engineering; Hu, Lin-Wen [Massachusetts Institute of Technology, Cambridge (United States). Nuclear Reactor Lab.], e-mail: lwhu@mit.edu

    2009-07-01

    A new fluorinated ketone, C{sub 2}F{sub 5}C(O)CF(CF{sub 3}){sub 2}, is currently being considered as an environmentally friendly alternative for power electronics cooling applications due to its high dielectric strength and low global warming potential (GWP). Sold commercially by the 3M Company as Novec{sup TM} 649 Engineered Fluid, C{sub 2}F{sub 5}C(O)CF(CF{sub 3}){sub 2} exhibits very low acute toxicity while maintaining long-term stability. To assess the general two-phase heat transfer performance of Novec{sup TM} 649, pool boiling tests were conducted by resistively heating a 0.01 in. diameter nickel wire at the fluid's atmospheric saturation temperature of 49 deg C. The nucleate boiling heat transfer coefficient and critical heat flux (CHF) obtained for the fluorinated ketone compare favorably with results obtained for FC-72, a fluorocarbon widely used for the direct cooling of electronic devices. Initial results indicate that Novec{sup TM} 649 may prove to be a viable alternative to FC-72 and other halo alkanes for the cooling of high power density electronic devices. (author)

  15. Effects of polymerization and briquetting parameters on the tensile strength of briquettes formed from coal coke and aniline-formaldehyde resin

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A.; Simsek, T. [Selcuk University, Konya (Turkey)

    2006-10-15

    In this work, the utilization of aniline (C{sub 6}H{sub 7}N) formaldehyde (HCHO) resins as a binding agent of coke briquetting was investigated. Aniline (AN) formaldehyde (F) resins are a family of thermoplastics synthesized by condensing AN and F in an acid solution exhibiting high dielectric strength. The tensile strength sharply increases as the ratio of F to AN from 0.5 to 1.6, and it reaches the highest values between 1.6 and 2.2 F/AN ratio; it then slightly decreases. The highest tensile strength of F-AN resin-coke briquette (23.66 MN/m{sup 2}) was obtained from the run with 1.5 of F/AN ratio by using (NH4){sub 2}S{sub 2}O{sub 8} catalyst at 310 K briquetting temperature. The tensile strength of F-AN resin-coke briquette slightly decreased with increasing the catalyst percent to 0.10%, and then it sharply decreased to zero with increasing the catalyst percent to 0.2%. The effect of pH on the tensile strength is irregular. As the pH of the mixture increases from 9.0 to 9.2, the tensile strength shows a sharp increase, and the curve reaches a plateau value between pH 9.3 and 9.9; then the tensile strength shows a slight increase after pH = 9.9.

  16. Pool boiling performance of NovecTM 649 engineered fluid

    International Nuclear Information System (INIS)

    Forrest, Eric; Buongiorno, Jacopo; McKrell, Thomas; Hu, Lin-Wen

    2009-01-01

    A new fluorinated ketone, C 2 F 5 C(O)CF(CF 3 ) 2 , is currently being considered as an environmentally friendly alternative for power electronics cooling applications due to its high dielectric strength and low global warming potential (GWP). Sold commercially by the 3M Company as Novec TM 649 Engineered Fluid, C 2 F 5 C(O)CF(CF 3 ) 2 exhibits very low acute toxicity while maintaining long-term stability. To assess the general two-phase heat transfer performance of Novec TM 649, pool boiling tests were conducted by resistively heating a 0.01 in. diameter nickel wire at the fluid's atmospheric saturation temperature of 49 deg C. The nucleate boiling heat transfer coefficient and critical heat flux (CHF) obtained for the fluorinated ketone compare favorably with results obtained for FC-72, a fluorocarbon widely used for the direct cooling of electronic devices. Initial results indicate that Novec TM 649 may prove to be a viable alternative to FC-72 and other halo alkanes for the cooling of high power density electronic devices. (author)

  17. Effects of Complex Structured Anodic Oxide Dielectric Layer Grown in Pore Matrix for Aluminum Capacitor.

    Science.gov (United States)

    Shin, Jin-Ha; Yun, Sook Young; Lee, Chang Hyoung; Park, Hwa-Sun; Suh, Su-Jeong

    2015-11-01

    Anodization of aluminum is generally divided up into two types of anodic aluminum oxide structures depending on electrolyte type. In this study, an anodization process was carried out in two steps to obtain high dielectric strength and break down voltage. In the first step, evaporated high purity Al on Si wafer was anodized in oxalic acidic aqueous solution at various times at a constant temperature of 5 degrees C. In the second step, citric acidic aqueous solution was used to obtain a thickly grown sub-barrier layer. During the second anodization process, the anodizing potential of various ranges was applied at room temperature. An increased thickness of the sub-barrier layer in the porous matrix was obtained according to the increment of the applied anodizing potential. The microstructures and the growth of the sub-barrier layer were then observed with an increasing anodizing potential of 40 to 300 V by using a scanning electron microscope (SEM). An impedance analyzer was used to observe the change of electrical properties, including the capacitance, dissipation factor, impedance, and equivalent series resistance (ESR) depending on the thickness increase of the sub-barrier layer. In addition, the breakdown voltage was measured. The results revealed that dielectric strength was improved with the increase of sub-barrier layer thickness.

  18. Determination of Carrier Polarity in Fowler-Nordheim Tunneling and Evidence of Fermi Level Pinning at the Hexagonal Boron Nitride/Metal Interface.

    Science.gov (United States)

    Hattori, Yoshiaki; Taniguchi, Takashi; Watanabe, Kenji; Nagashio, Kosuke

    2018-04-11

    Hexagonal boron nitride (h-BN) is an important insulating substrate for two-dimensional (2D) heterostructure devices and possesses high dielectric strength comparable to SiO 2 . Here, we report two clear differences in their physical properties. The first one is the occurrence of Fermi level pinning at the metal/h-BN interface, unlike that at the metal/SiO 2 interface. The second one is that the carrier of Fowler-Nordheim (F-N) tunneling through h-BN is a hole, which is opposite to an electron in the case of SiO 2 . These unique characteristics are verified by I- V measurements in the graphene/h-BN/metal heterostructure device with the aid of a numerical simulation, where the barrier height of graphene can be modulated by a back gate voltage owing to its low density of states. Furthermore, from a systematic investigation using a variety of metals, it is confirmed that the hole F-N tunneling current is a general characteristic because the Fermi levels of metals are pinned in the small energy range around ∼3.5 eV from the top of the conduction band of h-BN, with a pinning factor of 0.30. The accurate energy band alignment at the h-BN/metal interface provides practical knowledge for 2D heterostructure devices.

  19. High rate resistive plate chambers: An inexpensive, fast, large area detector of energetic charged particles for accelerator and non-accelerator applications

    International Nuclear Information System (INIS)

    Wuest, C.R.; Ables, E.; Bionta, R.M.; Clamp, O.; Haro, M.; Mauger, G.J.; Miller, K.; Olson, H.; Ramsey, P.

    1993-05-01

    Resistive Plate Chambers, or RPCs, have been used until recently as large detectors of cosmic ray muons. They are now finding use as fast large-area trigger and muon detection systems for different high energy physics detectors such the L3 Detector at LEP and future detectors to be built at the Superconducting Super Collider (SSC) and at the Large Hadron Collider (LHC) at CERN. RPC systems at these accelerators must operate with high efficiency, providing nanosecond timing resolution in particle fluences up to a few tens of kHz/cm 2 -- with thousands of square meters of active area. RPCs are simple and cheap to construct. The authors report here recent work on RPCs using new materials that exhibit a combination of desirable RPC features such as low bulk resistivity, high dielectric strength, low mass, and low cost. These new materials were originally developed for use in electronics assembly areas and other applications, where static electric charge buildup can damage sensitive electrical systems

  20. A highly stretchable autonomous self-healing elastomer

    Science.gov (United States)

    Li, Cheng-Hui; Wang, Chao; Keplinger, Christoph; Zuo, Jing-Lin; Jin, Lihua; Sun, Yang; Zheng, Peng; Cao, Yi; Lissel, Franziska; Linder, Christian; You, Xiao-Zeng; Bao, Zhenan

    2016-06-01

    It is a challenge to synthesize materials that possess the properties of biological muscles—strong, elastic and capable of self-healing. Herein we report a network of poly(dimethylsiloxane) polymer chains crosslinked by coordination complexes that combines high stretchability, high dielectric strength, autonomous self-healing and mechanical actuation. The healing process can take place at a temperature as low as -20 °C and is not significantly affected by surface ageing and moisture. The crosslinking complexes used consist of 2,6-pyridinedicarboxamide ligands that coordinate to Fe(III) centres through three different interactions: a strong pyridyl-iron one, and two weaker carboxamido-iron ones through both the nitrogen and oxygen atoms of the carboxamide groups. As a result, the iron-ligand bonds can readily break and re-form while the iron centres still remain attached to the ligands through the stronger interaction with the pyridyl ring, which enables reversible unfolding and refolding of the chains. We hypothesize that this behaviour supports the high stretchability and self-healing capability of the material.

  1. Fifty years of mapping the Balkan flora for Atlas Florae Europaeae

    Directory of Open Access Journals (Sweden)

    Uotila Pertti

    2017-10-01

    Full Text Available Atlas Florae Europaeae (AFE, a programme for mapping the distribution of vascular plants in Europe, was launched in 1965 as a collaborative effort between European botanists. A historical review of the mapping for AFE in the Balkan countries, cited in the last volume (16 from 2013 as Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Former Yugoslav Republic (F. Y. R. of Macedonia, Greece, Kosovo, Montenegro, Serbia, Slovenia, and Turkey (European part, is presented and achievements and problems discussed. The special challenges facing mapping of the Balkan area during the past 50 years include the extremely rich flora, diverse and mountainous relief, political and economic difficulties, inaccessibility of available data, and scarcity of botanists contributing and collecting data for mapping.

  2. Design of a wideband CMOS impedance spectroscopy ASIC analog front-end for multichannel biosensor interfaces.

    Science.gov (United States)

    Valente, Virgilio; Dai Jiang; Demosthenous, Andreas

    2015-08-01

    This paper presents the preliminary design and simulation of a flexible and programmable analog front-end (AFE) circuit with current and voltage readout capabilities for electric impedance spectroscopy (EIS). The AFE is part of a fully integrated multifrequency EIS platform. The current readout comprises of a transimpedance stage and an automatic gain control (AGC) unit designed to accommodate impedance changes larger than 3 order of magnitude. The AGC is based on a dynamic peak detector that tracks changes in the input current over time and regulates the gain of a programmable gain amplifier in order to optimise the signal-to-noise ratio. The system works up to 1 MHz. The voltage readout consists of a 2 stages of fully differential current-feedback instrumentation amplifier which provide 100 dB of CMRR and a programmable gain up to 20 V/V per stage with a bandwidth in excess of 10MHz.

  3. Pseudo-differential CMOS analog front-end circuit for wide-bandwidth optical probe current sensor

    Science.gov (United States)

    Uekura, Takaharu; Oyanagi, Kousuke; Sonehara, Makoto; Sato, Toshiro; Miyaji, Kousuke

    2018-04-01

    In this paper, we present a pseudo-differential analog front-end (AFE) circuit for a novel optical probe current sensor (OPCS) aimed for high-frequency power electronics. It employs a regulated cascode transimpedance amplifier (RGC-TIA) to achieve a high gain and a large bandwidth without using an extremely high performance operational amplifier. The AFE circuit is designed in a 0.18 µm standard CMOS technology achieving a high transimpedance gain of 120 dB Ω and high cut off frequency of 16 MHz. The measured slew rate is 70 V/µs and the input referred current noise is 1.02 pA/\\sqrt{\\text{Hz}} . The magnetic resolution and bandwidth of OPCS are estimated to be 1.29 mTrms and 16 MHz, respectively; the bandwidth is higher than that of the reported Hall effect current sensor.

  4. A low power low noise analog front end for portable healthcare system

    International Nuclear Information System (INIS)

    Wang Yanchao; Ke Keren; Qin Wenhui; Qin Yajie; Yi Ting; Hong Zhiliang

    2015-01-01

    The presented analog front end (AFE) used to process human bio-signals consists of chopping instrument amplifier (IA), chopping spikes filter and programmable gain and bandwidth amplifier. The capacitor-coupling input of AFE can reject the DC electrode offset. The power consumption of current-feedback based IA is reduced by adopting capacitor divider in the input and feedback network. Besides, IA's input thermal noise is decreased by utilizing complementary CMOS input pairs which can offer higher transconductance. Fabricated in Global Foundry 0.35 μm CMOS technology, the chip consumes 3.96 μA from 3.3 V supply. The measured input noise is 0.85 μVrms (0.5–100 Hz) and the achieved noise efficient factor is 6.48. (paper)

  5. Electric-field tunable perpendicular magnetic anisotropy in tetragonal Fe4N/BiFeO3 heterostructures

    Science.gov (United States)

    Yin, Li; Wang, Xiaocha; Mi, Wenbo

    2017-07-01

    Electric field control on perpendicular magnetic anisotropy (PMA) is indispensable for spintronic devices. Herewith, in tetragonal Fe4N/BiFeO3 heterostructures with the FeAFeB/Fe-O2 interface, PMA in each Fe4N layer, not merely interfacial layers, is modulated by the electric field, which is attributed to the broken spin screening of the electric field in highly spin-polarized Fe4N. Moreover, the periodical dx y+dy z+dz2 and dx y+dx2-y2 orbital-PMA oscillation enhances the interactions between adjacent FeAFeB and (FeB)2N atomic layers, which benefits the electric field modulation on PMA in the whole Fe4N atomic layers. The electric-field control on PMA in Fe4N/BiFeO3 heterostructures is favored by the electric-field-lifted potential in Fe4N.

  6. A reconfigurable medically cohesive biomedical front-end with ΣΔ ADC in 0.18µm CMOS.

    Science.gov (United States)

    Jha, Pankaj; Patra, Pravanjan; Naik, Jairaj; Acharya, Amit; Rajalakshmi, P; Singh, Shiv Govind; Dutta, Ashudeb

    2015-08-01

    This paper presents a generic programmable analog front-end (AFE) for acquisition and digitization of various biopotential signals. This includes a lead-off detection circuit, an ultra-low current capacitively coupled signal conditioning stage with programmable gain and bandwidth, a new mixed signal automatic gain control (AGC) mechanism and a medically cohesive reconfigurable ΣΔ ADC. The full system is designed in UMC 0.18μm CMOS. The AFE achieves an overall linearity of more 10 bits with 0.47μW power consumption. The ADC provides 2(nd) order noise-shaping while using single integrator and an ENOB of ~11 bits with 5μW power consumption. The system was successfully verified for various ECG signals from PTB database. This system is intended for portable batteryless u-Healthcare devices.

  7. Code it rite the first time : automated invoice processing solution designed to ensure validity to field ticket coding

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, G.

    2010-03-15

    An entrepreneur who ran 55 rigs for a major oilfield operator in Calgary has developed a solution for the oil industry that reduces field ticketing errors from 40 per cent to almost none. The Code-Rite not only simplifies field ticketing but can eliminate weeks of trying to balance authorization for expenditure (AFE) numbers. A service provider who wants a field ticket signed for billing purposes following a service call to a well site receives all pertinent information on a barcode that includes AFE number, location, routing, approval authority and mailing address. Attaching the label to the field ticket provides all the invoicing information needed. This article described the job profile, education and life experiences and opportunities that led the innovator to develop this technology that solves an industry-wide problem. Code-Rite is currently being used by 3 large upstream oil and gas operators and plans are underway to automate the entire invoice processing system. 1 fig.

  8. Low resistivity contact to iron-pnictide superconductors

    Science.gov (United States)

    Tanatar, Makariy; Prozorov, Ruslan; Ni, Ni; Bud& #x27; ko, Sergey; Canfield, Paul

    2013-05-28

    Method of making a low resistivity electrical connection between an electrical conductor and an iron pnictide superconductor involves connecting the electrical conductor and superconductor using a tin or tin-based material therebetween, such as using a tin or tin-based solder. The superconductor can be based on doped AFe.sub.2As.sub.2, where A can be Ca, Sr, Ba, Eu or combinations thereof for purposes of illustration only.

  9. Lying for Strategic Advantage: Rational and Boundedly Rational Misrepresentation of Intentions

    OpenAIRE

    Crawford, Vincent P.

    2001-01-01

    Starting from Hendricks and McAfee's (2000) example of the Allies' decision to feint at Calais and attack at Normandy on D-Day, this paper models misrepresentation of intentions to competitors or enemies. Allowing for the possibility of bounded strategic rationality and rational players' responses to it yields a sensible account of lying via costless, noiseless messages. In many cases the model has generically unique pure-strategy sequential equilibria, in which rational players exploit bound...

  10. Frequency to Voltage Converter Analog Front-End Prototype

    Science.gov (United States)

    Mata, Carlos; Raines, Matthew

    2012-01-01

    The frequency to voltage converter analog front end evaluation prototype (F2V AFE) is an evaluation board designed for comparison of different methods of accurately extracting the frequency of a sinusoidal input signal. A configurable input stage is routed to one or several of five separate, configurable filtering circuits, and then to a configurable output stage. Amplifier selection and gain, filter corner frequencies, and comparator hysteresis and voltage reference are all easily configurable through the use of jumpers and potentiometers.

  11. How to Keep Your Campus Safe from Infection

    Science.gov (United States)

    Brown, Scott

    2005-01-01

    In this article, the author explains how antivirus programs work. He also explains how performances of various antivirus programs vary from one to another. He also takes a look at 13 antivirus programs and explains which of these will keep computers protected. These programs include: (1) Sophos Anti-Virus Version 3.86.2; (2) McAfee VirusScan 9.0;…

  12. An EXAFS Study on the Local Structure Around Iron in Atmospheric Aerosols Collected in the Qingdao Area

    Directory of Open Access Journals (Sweden)

    Tiandou Hu

    2003-01-01

    Full Text Available The existing forms of Fe are of great interest since they have a profound effect on the biological availability of Fe. In this work, aerosol samples collected in different seasons and at different locations in the Qingdao region were examined by means of extended X-ray absorption fine structure (EXAFS K-edge analysis of Fe, X-ray diffraction (XRD and Fe content analysis. The results showed that an iron ion in aerosol particles is surrounded on average by 5.8 (coordinated O ions. For the six samples examined, the coordination number of the first Fe-O coordination subshell is always 3 with a coordination distance (with O in the range of 1.952~1.966±0.002 Å, while the coordination number of the second subshell varies from 2.2 to 3.0 with a coordination distance of 2.108±0.002 Å. The coordination is approximately consistent with that of a-Fe2O3, suggesting that iron in aerosol samples is mainly present in the form of a-Fe2O3. The fact that the coordination number in the second subshell is smaller than that of a-Fe2O3 might be an indication that there is a small amount of FeO mixed with a-Fe2O3 in aerosol particles. Existence of FeO is confirmed by a later XRD experiment.

  13. Task-based detectability comparison of exponential transformation of free-response operating characteristic (EFROC) curve and channelized Hotelling observer (CHO)

    Science.gov (United States)

    Khobragade, P.; Fan, Jiahua; Rupcich, Franco; Crotty, Dominic J.; Gilat Schmidt, Taly

    2016-03-01

    This study quantitatively evaluated the performance of the exponential transformation of the free-response operating characteristic curve (EFROC) metric, with the Channelized Hotelling Observer (CHO) as a reference. The CHO has been used for image quality assessment of reconstruction algorithms and imaging systems and often it is applied to study the signal-location-known cases. The CHO also requires a large set of images to estimate the covariance matrix. In terms of clinical applications, this assumption and requirement may be unrealistic. The newly developed location-unknown EFROC detectability metric is estimated from the confidence scores reported by a model observer. Unlike the CHO, EFROC does not require a channelization step and is a non-parametric detectability metric. There are few quantitative studies available on application of the EFROC metric, most of which are based on simulation data. This study investigated the EFROC metric using experimental CT data. A phantom with four low contrast objects: 3mm (14 HU), 5mm (7HU), 7mm (5 HU) and 10 mm (3 HU) was scanned at dose levels ranging from 25 mAs to 270 mAs and reconstructed using filtered backprojection. The area under the curve values for CHO (AUC) and EFROC (AFE) were plotted with respect to different dose levels. The number of images required to estimate the non-parametric AFE metric was calculated for varying tasks and found to be less than the number of images required for parametric CHO estimation. The AFE metric was found to be more sensitive to changes in dose than the CHO metric. This increased sensitivity and the assumption of unknown signal location may be useful for investigating and optimizing CT imaging methods. Future work is required to validate the AFE metric against human observers.

  14. Using Mobile Platforms for Sensitive Government Business

    Science.gov (United States)

    2013-01-01

    install call, text and data monitoring software within the corporate enclave(s), in order to meter professional usage separately. Personal usage could be...Available from: http://www.3gpp.org/ftp/Specs/archive/33_series/33.908/33908- 400 .zip. 27. Geiger, H. NFC Phones Raise Opportunities, Privacy And...Available from: http://www.pcworld.com/article/212192/protect_your_android_phone_with_sec urity_apps.html. 74. German, K. Sprint offers McAfee

  15. Critical Thinking in Higher Education: An Annotated Bibliography

    Directory of Open Access Journals (Sweden)

    Mary Shriner, MLS

    2006-08-01

    Full Text Available An overwhelming number of books and full-text articles on various databases are available that suggest ways to teach critical thinking. Most educators agree that this skill is becoming increasingly important as classes become more diversified and the curriculum becomes more global. An institution’s library is an often-overlooked faculty development resource; this article offers relevant articles on critical thinking from the many databases available through Park University's McAfee Memorial Library.

  16. Modernity Evaluation of the Machines Used During Production Process of Metal Products

    OpenAIRE

    Ingaldi, Manuela; Dziuba, Szymon T.

    2015-01-01

    Most manufacturing companies realize its technologies, implemented through concrete machinery parts. They differ in terms of importance, the relevance of their selection and the level of their modernity. Modernity and efficiency of the machine are also very important during production process of the metal products. They have an influence on the quality of these products. The purpose of this article is to analyse the chosen production machine (CNC machine AFE-3D8-T) used during pro...

  17. FY12 Line-Supported Bio-Medical Initiative Program: Advanced Photoplethysmography (PPG) Sensors for Operational and Casualty Care Medicine

    Science.gov (United States)

    2013-02-11

    940 nm) wavelengths; 2) red/NIR enhanced photodiodes to transduce optical energy into electrical energy; 3) transimpedance amplifier (TIA) to amplify ...Tavakoli, M., L. Turicchia, and R. Sarpeshkar, “An Ultra-Low-Power Pulse Oximeter Implemented with an Energy-Efficient Transimpedance Amplifier .” IEEE...which uses optical energy modulated by blood flow; the analog front end (AFE), which amplifies and filters the received signal; and the digital backend

  18. Production in food of 1,3-pentadiene and styrene by Trichoderma species

    CSIR Research Space (South Africa)

    Pinches, SE

    2007-05-01

    Full Text Available against other fungi (Dennis and Webster, 1971) although the antimicrobial properties of 1,3-pentadiene and styrene are not established. In foods, the presence of either or both of the compounds imparts repellent smells and highly disagreeable off... tainting compounds are indeed produced in the presence of sorbic acid and cinnamic acid, but not if the corresponding precursors are absent. Trichoderma moulds are known to produce a wide range of volatile organic compounds, (VOCs) (McAfee and Taylor...

  19. Identification of Promising Mutants Associated with Egg Production Traits Revealed by Genome-Wide Association Study.

    Directory of Open Access Journals (Sweden)

    Jingwei Yuan

    Full Text Available Egg number (EN, egg laying rate (LR and age at first egg (AFE are important production traits related to egg production in poultry industry. To better understand the knowledge of genetic architecture of dynamic EN during the whole laying cycle and provide the precise positions of associated variants for EN, LR and AFE, laying records from 21 to 72 weeks of age were collected individually for 1,534 F2 hens produced by reciprocal crosses between White Leghorn and Dongxiang Blue-shelled chicken, and their genotypes were assayed by chicken 600 K Affymetrix high density genotyping arrays. Subsequently, pedigree and SNP-based genetic parameters were estimated and a genome-wide association study (GWAS was conducted on EN, LR and AFE. The heritability estimates were similar between pedigree and SNP-based estimates varying from 0.17 to 0.36. In the GWA analysis, we identified nine genome-wide significant loci associated with EN of the laying periods from 21 to 26 weeks, 27 to 36 weeks and 37 to 72 weeks. Analysis of GTF2A1 and CLSPN suggested that they influenced the function of ovary and uterus, and may be considered as relevant candidates. The identified SNP rs314448799 for accumulative EN from 21 to 40 weeks on chromosome 5 created phenotypic differences of 6.86 eggs between two homozygous genotypes, which could be potentially applied to the molecular breeding for EN selection. Moreover, our finding showed that LR was a moderate polygenic trait. The suggestive significant region on chromosome 16 for AFE suggested the relationship between sex maturity and immune in the current population. The present study comprehensively evaluates the role of genetic variants in the development of egg laying. The findings will be helpful to investigation of causative genes function and future marker-assisted selection and genomic selection in chickens.

  20. Functional Analysis of Battery Management Systems using Multi-Cell HIL Simulator

    OpenAIRE

    Barreras, Jorge Varela; Swierczynski, Maciej Jozef; Schaltz, Erik; Andreasen, Søren Juhl; Fleischer, Christian; Sauer, Dirk Uwe; Christensen, Andreas Elkjær

    2015-01-01

    Developers and manufacturers of Battery Management Systems (BMSs) require extensive testing of controller HW and SW, such as analog front-end (AFE) and performance of generated control code. In comparison with tests conducted on real batteries, tests conducted on hardware-in-the-loop (HIL) simulator may be more costant time effective, easier to reproduce and safer beyond the normal range of operation, especially at early stages in the development process or during fault simulation. In this pa...

  1. Photoelectrochemical Characterization of Sprayed alpha-Fe2O3 Thin Films : Influence of Si Doping and SnO2 Interfacial Layer

    NARCIS (Netherlands)

    Liang, Y.; Enache, C.S.; Van De Krol, R.

    2008-01-01

    a-Fe2O3 thin film photoanodes for solar water splitting were prepared by spray pyrolysis of Fe(AcAc)3. The donor density in the Fe2O3 films could be tuned between 10171020cm-3 by doping with silicon. By depositing a 5 nm SnO2 interfacial layer between the Fe2O3 films and the transparent conducting

  2. Fecal incontinence, sexual complaints, and anorectal function after third-degree obstetric anal sphincter injury (OASI): 5-year follow-up.

    Science.gov (United States)

    Visscher, A P; Lam, T J; Hart, N; Felt-Bersma, R J F

    2014-05-01

    Our aim was to evaluate alterations in anorectal function after anal sphincteroplasty for third-degree obstetric anal sphincter injury (OASI) in relation to clinical outcome. In this retrospective, descriptive, cross-sectional study conducted between 1998 and 2008, women with persisting fecal incontinence (FI) after 3a OASI and all women with grade 3b or 3c OASI were sent for anorectal function evaluation (AFE) consisting of anal manometry and endosonography 3 months after sphincteroplasty. In 2011, questionnaires regarding FI (Vaizey/Wexner), urinary incontinence (UI) [International Consultation on Incontinence Questionnaire Short Form (ICIQ-SF)], sexual function [Female Sexual Function Index (FSFI)], and quality of life (QOL) (Rand-36) were sent and women were asked to undergo additional AFE. Sixty-six women underwent AFE. Mean follow-up was 5.0 years. Forty (61%) patients returned questionnaires regarding FI and UI. Prevalence of FI was 63% flatus, 50% liquid stool, and 20% solid stool. Thirty-two of 40 also reported on QOL and SF. Sexual dysfunction was present in the majority of women (cutoff value 26.55) and more pronounced in larger OASI. Sixteen of 40 women underwent additional AFE. Women with combined internal (IAS) and external (EAS) anal sphincter injury (n = 6) had worse FI (P 40) than women with isolated EAS injury (n = 10). Follow-up after third-degree OASI suggests poor anorectal and sexual function. Women with combined external and internal OASI show more deterioration in anorectal function and experience worse FI. Therefore, special attention should be paid to these women in order to mitigate these symptoms later in life.

  3. RADIO NOISE ADVANCES SEXUAL MATURITY

    African Journals Online (AJOL)

    ansistf-lewis

    Mean age at first egg for the radio birds (143 d) was 13 d significantly earlier than controls, but body weight at ... the first 8 h of a 12-h photoperiod with radio noise, to leave only 4 h of light (4L:20D), supported rates of lay ... Age (AFE) and body weight at, and weight of, first egg were recorded for individual birds, and, after a.

  4. Army Justified Initial Production Plan for the Paladin Integrated Management Program but Has Not Resolved Two Vehicle Performance Deficiencies (Redacted)

    Science.gov (United States)

    2016-08-05

    model oversight organization in the Federal Government by leading change, speaking truth, and promoting excellence—a diverse organization, working ...VIRGINIA 22350-1500 August 5, 2016 MEMORANDUM FOR AUDITOR GENERAL, DEPARTMENT OF THE ARMY SUBJECT: Army Justified Initial Production Plan for the Paladin... Family of Vehicles, M109A7 Self-Propelled Howitzer and M992A3 Carrier, Ammunition, Tracked, October 2015; • M109A7 AFES Overview, September 2015

  5. Tips From Former Smokers – 2013 Campaign

    Centers for Disease Control (CDC) Podcasts

    2013-03-28

    Tim McAfee, MD, MPH, of CDC’s Office on Smoking and Health, discusses the 2013 Tips campaign, and his personal experience as a doctor treating people with diseases caused by smoking, or made worse by it. He also offers advice on how people can quit smoking.  Created: 3/28/2013 by Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion.   Date Released: 3/28/2013.

  6. A Comparison of the Usefulness of the Facilities Management Program in the Graduate School of Systems and Logistics and Similar Programs in Civilian Institutions as Perceived by Former Students

    Science.gov (United States)

    1980-06-01

    8217 043FCCBCAAACCEGEFFEEEDGGFFEEGFFFFEGEECFFED6OGFEAFE’FIHBI 0441CC AABC ABA AA AA AA A AFEEAA AA AA A A AOF A A A AAG AA A A AAA FHAL’ 045 F C FAA A CAGOGGOA FF00 FOB El’C...thesis. SLSR 13-69, A"FT/SL, Wright-Patterson AFE Ofil, August, 1968. AD 846434. Hale, Captain Jerry W., and Captain Basil E. Rooney. "A Deter

  7. Commercial Contracting of Army Lodging and Leisure Activities.

    Science.gov (United States)

    1985-05-22

    The Burger King outlets will be operated by AAFES. AAFES will pay Burger King $15,000 for each franchise and six percent of the gross sales as...share of Burger King profits is projected to increase that net income by 30 to 40 percent.27 Contractors for construction and franchising of...individuals and groups to productivity.", In May of 1984 AFES executed a contractual arrangement with the civilian enterprise Burger King . Burger King has

  8. Software and the Virus Threat: Providing Authenticity in Distribution

    Science.gov (United States)

    1991-03-01

    x . . . x x x x . 2100 Plastique (9) . x x x x x . . x x , . . 3012 Wo ian (2) . x x x x . . . x x . . . . 2064 Doom Z x . x x. . x x x x 2504 Flip...shot+ Software Concepts Design (212) 889 6438 594 Third Avenue New York, NY 10016 FShield McAfee Associates (408) 988-3832 4423 Cheeney Street Santa

  9. Positive Impacts of Social Media at Work: Job Satisfaction, Job Calling, and Facebook Use among Co-Workers

    OpenAIRE

    Hanna Brittany; Kee Kerk F.; Robertson Brett W.

    2017-01-01

    The number of Facebook users grew rapidly since its conception. Within today’s workplace, employees are increasingly connecting with each other on Facebook for interpersonal reasons. Due to sensational reports by media outlets of inappropriate social media use, many organizations are taking extreme measures about how their employees who utilize Facebook to connect with colleagues. Contrary to the negative assumptions, McAfee [1] states that social media within the workplace can promote positi...

  10. Design and Control of a 13.2 kV/10 kVA Single-Phase Solid-State-Transformer with 1.7 kV SiC Devices

    Directory of Open Access Journals (Sweden)

    Jeong-Woo Lim

    2018-01-01

    Full Text Available This paper describes the power stage design, control, and performance evaluation of a 13.2 kV/10 kVA solid-state-transformer (SST for a power distribution system. The proposed SST consists of 10 modules where each individual module contains a unidirectional three-level power factor correction (PFC converter for the active-front-end (AFE stage and an LLC resonant converter for the isolated DC-DC stage. The operating principles of the converters are analyzed and the modulation and the control schemes for the entire module are described in detail. The DC-link voltage imbalance is also less than other SST topologies due to the low number of uncontrollable switching states. In order to simplify the control of the power stage, a modulation strategy for the AFE stage is proposed, and the modulation frequency of the LLC converter is also fixed. In addition, a compensation algorithm is suggested to eliminate the current measurement offset in the AFE stage. The proposed SST achieves the unity power factor at the input AC current regardless of the reactive or nonlinear load and a low voltage regulation at the AC output. In order to verify the effectiveness of the SST, the 13.2 kV/10 kV SST prototype is built and tested. Both the simulation and the experimental results under actual 13.2 kV line show the excellent performance of the proposed SST scheme.

  11. Inhibition of Mast Cell-Mediated Allergic Responses by Arctii Fructus Extracts and Its Main Compound Arctigenin.

    Science.gov (United States)

    Kee, Ji-Ye; Hong, Seung-Heon

    2017-11-01

    The Arctium lappa seeds (Arctii Fructus) and its major active compound, arctigenin (ARC), are known to have anticancer, antiobesity, antiosteoporosis, and anti-inflammatory activities. However, the effect of Arctii Fructus and ARC on mast cell-mediated allergic inflammation and its associated mechanism have not been elucidated. Therefore, we attempted to investigate the antiallergic activity of Arctii Fructus and ARC on mast cells and experimental mouse models. Arctii Fructus water extract (AFW) or ethanol extract (AFE) and ARC reduced the production of histamine and pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and TNF-α in mast cells. AFW, AFE, and ARC inhibited phosphorylation of MAPKs and NF-κB in activated mast cells. Moreover, IgE-mediated passive cutaneous anaphylaxis and compound 48/80-induced anaphylactic shock were suppressed by AFW, AFE, and ARC administration. These results suggest that Arctii Fructus and ARC are potential therapeutic agents against allergic inflammatory diseases.

  12. A low-power portable ECG sensor interface with dry electrodes

    International Nuclear Information System (INIS)

    Pu Xiaofei; Wan Lei; Zhang Hui; Qin Yajie; Hong Zhiliang

    2013-01-01

    This paper describes a low-power portable sensor interface dedicated to sensing and processing electrocardiogram (ECG) signals. Dry electrodes were employed in this ECG sensor, which eliminates the need of conductive gel and avoids complicated and mandatory skin preparation before electrode attachment. This ECG sensor system consists of two ICs, an analog front-end (AFE) and a successive approximation register analog-to-digital converter (SAR ADC) containing a relaxation oscillator. This proposed design was fabricated in a 0.18 μm 1P6M standard CMOS process. The AFE for extracting the biopotential signals is essential in this ECG sensor. In measurements, the AFE obtains a mid-band gain of 45 dB, a bandwidth from 0.6 to 160 Hz, and a total input referred noise of 2.8 μV rms while consuming 1 μW from the 1.8 V supply. The noise efficiency factor (NEF) of our design is 3.4. After conditioning, the amplified ECG signal is digitized by a 12-bit SAR ADC with 61.8 dB SNDR and 220 fJ/conversion-step. Finally, a complete ECG sensor interface with three dry copper electrodes is demonstrated in real-word setting, showing successful recordings of a capture ECG waveform. (semiconductor integrated circuits)

  13. Toward 10-km mesh global climate simulations

    Science.gov (United States)

    Ohfuchi, W.; Enomoto, T.; Takaya, K.; Yoshioka, M. K.

    2002-12-01

    An atmospheric general circulation model (AGCM) that runs very efficiently on the Earth Simulator (ES) was developed. The ES is a gigantic vector-parallel computer with the peak performance of 40 Tflops. The AGCM, named AFES (AGCM for ES), was based on the version 5.4.02 of an AGCM developed jointly by the Center for Climate System Research, the University of Tokyo and the Japanese National Institute for Environmental Sciences. The AFES was, however, totally rewritten in FORTRAN90 and MPI while the original AGCM was written in FORTRAN77 and not capable of parallel computing. The AFES achieved 26 Tflops (about 65 % of the peak performance of the ES) at resolution of T1279L96 (10-km horizontal resolution and 500-m vertical resolution in middle troposphere to lower stratosphere). Some results of 10- to 20-day global simulations will be presented. At this moment, only short-term simulations are possible due to data storage limitation. As ten tera flops computing is achieved, peta byte data storage are necessary to conduct climate-type simulations at this super-high resolution global simulations. Some possibilities for future research topics in global super-high resolution climate simulations will be discussed. Some target topics are mesoscale structures and self-organization of the Baiu-Meiyu front over Japan, cyclogenecsis over the North Pacific and typhoons around the Japan area. Also improvement in local precipitation with increasing horizontal resolution will be demonstrated.

  14. A dual slope charge sampling analog front-end for a wireless neural recording system.

    Science.gov (United States)

    Lee, Seung Bae; Lee, Byunghun; Gosselin, Benoit; Ghovanloo, Maysam

    2014-01-01

    This paper presents a novel dual slope charge sampling (DSCS) analog front-end (AFE) architecture, which amplifies neural signals by taking advantage of the charge sampling concept for analog signal conditioning, such as amplification and filtering. The presented DSCS-AFE achieves amplification, filtering, and sampling in a simultaneous fashion, while consuming very small amount of power. The output of the DSCS-AFE produces a pulse width modulated (PWM) signal that is proportional to the input voltage amplitude. A circular shift register (CSR) utilizes time division multiplexing (TDM) of the PWM pulses to create a pseudo-digital TDM-PWM signal that can feed a wireless transmitter. The 8-channel system-on-a-chip was fabricated in a 0.35-μm CMOS process, occupying 2.4 × 2.1 mm(2) and consuming 255 μW from a 1.8V supply. Measured input-referred noise for the entire system, including the FPGA in order to recover PWM signal is 6.50 μV(rms) in the 288 Hz~10 kHz range. For each channel, sampling rate is 31.25 kHz, and power consumption is 31.8 μW.

  15. A low-power high-sensitivity analog front-end for PPG sensor.

    Science.gov (United States)

    Binghui Lin; Atef, Mohamed; Guoxing Wang

    2017-07-01

    This paper presents a low-power analog front-end (AFE) photoplethysmography (PPG) sensor fabricated in 0.35 μm CMOS process. The AFE amplifies the weak photocurrent from the photodiode (PD) and converts it to a strong voltage at the output. In order to decrease the power consumption, the circuits are designed in subthreshold region; so the total biasing current of the AFE is 10 μ A. Since the large input DC photocurrent is a big issue for the PPG sensing circuit, we apply a DC photocurrent rejection technique by adding a DC current-cancellation loop to reject the large DC photocurrent up to 10 μA. In addition, a pseudo resistor is used to reduce the high-pass corner frequency below 0.5 Hz and Gm-C filter is adapted to reject the out-of-band noise higher than 16 Hz. For the whole sensor, the amplifier chain can achieve a total gain of 140 dBμ and an input integrated noise current of 68.87 pA rms up to 16 Hz.

  16. Amniotic fluid embolism

    Directory of Open Access Journals (Sweden)

    Kiranpreet Kaur

    2016-01-01

    Full Text Available Amniotic fluid embolism (AFE is one of the catastrophic complications of pregnancy in which amniotic fluid, fetal cells, hair, or other debris enters into the maternal pulmonary circulation, causing cardiovascular collapse. Etiology largely remains unknown, but may occur in healthy women during labour, during cesarean section, after abnormal vaginal delivery, or during the second trimester of pregnancy. It may also occur up to 48 hours post-delivery. It can also occur during abortion, after abdominal trauma, and during amnio-infusion. The pathophysiology of AFE is not completely understood. Possible historical cause is that any breach of the barrier between maternal blood and amniotic fluid forces the entry of amniotic fluid into the systemic circulation and results in a physical obstruction of the pulmonary circulation. The presenting signs and symptoms of AFE involve many organ systems. Clinical signs and symptoms are acute dyspnea, cough, hypotension, cyanosis, fetal bradycardia, encephalopathy, acute pulmonary hypertension, coagulopathy etc. Besides basic investigations lung scan, serum tryptase levels, serum levels of C3 and C4 complements, zinc coproporphyrin, serum sialyl Tn etc are helpful in establishing the diagnosis. Treatment is mainly supportive, but exchange transfusion, extracorporeal membrane oxygenation, and uterine artery embolization have been tried from time to time. The maternal prognosis after amniotic fluid embolism is very poor though infant survival rate is around 70%.

  17. Attributable risk of carpal tunnel syndrome according to industry and occupation in a general population.

    Science.gov (United States)

    Roquelaure, Yves; Ha, Catherine; Nicolas, Guillaume; Pélier-Cady, Marie-Christine; Mariot, Camille; Descatha, Alexis; Leclerc, Annette; Raimbeau, Guy; Goldberg, Marcel; Imbernon, Ellen

    2008-09-15

    An epidemiologic surveillance network for carpal tunnel syndrome (CTS) was set up in the general population of a French region to assess the proportion of CTS cases attributable to work in high-risk industries and occupations. Cases of CTS occurring among patients ages 20-59 years living in the Maine and Loire region were included prospectively from 2002 to 2004. Medical and occupation history was gathered by mailed questionnaire for 815 women and 320 men. Age-adjusted relative risks of CTS and the attributable risk fractions of CTS among exposed persons (AFEs) were computed in relation to industry sectors and occupation categories. Twenty-one industry sectors and 8 occupational categories for women and 10 sectors and 6 occupational categories for men were characterized by a significant excess risk of CTS. High AFE values were observed in the manufacturing (42-93% for both sexes), construction (66% for men), and personal service industries (66% for women) and in the trade and commerce sectors (49% for women). High AFE values were observed in lower-grade white-collar occupations for women (43-67%) and blue-collar occupations for men (60-74%) and women (48-88%). The attributable proportions of CTS cases among workers employed in industry sectors and occupation categories identified at high risk of CTS varied between 36% and 93%.

  18. Ionic Mobility and Phase Transitions in Perovskite Oxides for Energy Application

    Directory of Open Access Journals (Sweden)

    Francesco Cordero

    2017-02-01

    Full Text Available Perovskite oxides find applications or are studied in many fields related to energy production, accumulation and saving. The most obvious application is oxygen or proton conductors in fuel cells (SOFCs, but the (antiferroelectric compositions may find application in high energy capacitors for energy storage, efficient electrocaloric cooling, and electromechanical energy harvesting. In SOFCs, the diffusion of O vacancies and other mobile ionic species, such as H+, are at the base of the functioning of the device, while in the other cases they constitute unwanted defects that reduce the performance and life-time of the device. Similarly, the (antiferroelectric phase transitions are a requisite for the use of some types of devices, but the accompanying domain walls can generate extended defects detrimental to the life of the material, and structural phase transformations should be avoided in SOFCs. All these phenomena can be studied by mechanical spectroscopy, the measurement of the complex elastic compliance as a function of temperature and frequency, which is the mechanical analogue of the dielectric susceptibility, but probes the elastic response and elastic dipoles instead of the dielectric response and electric dipoles. The two techniques can be combined to provide a comprehensive picture of the material properties. Examples are shown of the study of structural transitions and hopping and tunnelling processes of O vacancies and H in the ion conductor BaCe1-xYxO3-x and in SrTiO3-x, and of the aging and fatigue effects found in PZT at compositions where the ferro- and antiferroelectric states coexist.

  19. Electrocaloric effect and luminescence properties of lanthanide doped (Na1/2Bi1/2)TiO3 lead free materials

    International Nuclear Information System (INIS)

    Zannen, M.; Lahmar, A.; Asbani, B.; El Marssi, M.; Khemakhem, H.; Kutnjak, Z.; Es Souni, M.

    2015-01-01

    Polycrystalline lead-free Sodium Bismuth Titanate (NBT) ferroelectric ceramics doped with rare earth (RE) element are prepared using solid state reaction method. Optical, ferroelectric, and electrocaloric properties were investigated. The introduction of RE 3+ ions in the NBT host lattice shows different light emissions over the wavelength range from visible to near infrared region. The ferroelectric P-E hysteresis loops exhibit an antiferroelectric-like character near room temperature indicating possible existence of a morphotropic phase boundary. The enhanced electrocaloric response was observed in a broad temperature range due to nearly merged phase transitions. Coexistence of optical and electrocaloric properties is very promising for photonics or optoelectronic device applications

  20. Specific heat measurements in KCN:KCL mixed crystals

    International Nuclear Information System (INIS)

    Ghivelder, L.

    1983-01-01

    An adiabatic calorimeter to perform specific heat measurements of small samples (approximatelly 150 mg) was built. The measurements were taken from 6 to 120 K, iN KCN:KCL mixed crystals, in order to observe the evolution of the antiferroelectric phase transition - that occurs at 83 K in KCN pure. From the experimental results the values of the phase transition critical temperature are found, for some particular concentrations of the mixture, and it was detected that this phase transition disappears with only 10% of Cl - . This result is explained in terms of a change of the potential wells in the crystal. (Author) [pt

  1. Review of crystal and domain structures in the PbZrxTi1-xO3 solid solution

    DEFF Research Database (Denmark)

    Woodward, D.I.; Knudsen, J.; Reaney, I.M.

    2005-01-01

    Several intermediate phases have recently been identified in the PbZrxTi1-xO3 (PZT) phase diagram, located close to the antiferroelectric-ferroelectric and morphotropic phase boundaries. Superlattice reflections from some of these phases are clearly visible in the appropriate electron diffraction...... patterns and have therefore been used to provide further information concerning their symmetry. Here, the structural distortions giving rise to the new phases are discussed and their domain structures compared with those of tetragonal and rhombohedral PZT. Coherent structural arguments are presented...

  2. Lattice dynamics and central-mode phenomena in the dielectric response of ferroelectrics and related materials

    Czech Academy of Sciences Publication Activity Database

    Buixaderas, Elena; Kamba, Stanislav; Petzelt, Jan

    2004-01-01

    Roč. 308, - (2004), s. 131-192 ISSN 0015-0193 R&D Projects: GA ČR GA202/01/0612; GA AV ČR IAA1010213; GA MŠk OC 525.20 Institutional research plan: CEZ:AV0Z1010914 Keywords : phonons in crystal lattice * commensurate-incommensurate transitions * dielectric properties of solids and liquids * ferroelectricity and antiferroelectricity * niobates * tantantalates * PZT ceramics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  3. Examination of new chiral smectics with four aromatic rings

    Science.gov (United States)

    Żurowska, Magdalena; Czerwiński, Michał; Dziaduszek, Jerzy; Filipowicz, Marek

    2018-05-01

    This paper presents the results of the study of four chiral mesogens with the acronym (4X1X2). The investigated compounds might be of interest for use as components of multicomponent mixtures useful in technical devices. The compounds have high chemical stability. Their mesomorphic properties were tested by means of polarizing optical microscopy and differential scanning calorimetry. The helical pitch of the prepared compounds and mixtures was estimated using the selective reflection method. Their phase smectic layer structure and usefulness for formulation of multicomponent antiferroelectric mixtures were then reported.

  4. Multiferroic behavior associated with an order-disorder hydrogen bonding transition in metal-organic frameworks (MOFs) with the perovskite ABX3 architecture.

    Science.gov (United States)

    Jain, Prashant; Ramachandran, Vasanth; Clark, Ronald J; Zhou, Hai Dong; Toby, Brian H; Dalal, Naresh S; Kroto, Harold W; Cheetham, Anthony K

    2009-09-30

    Multiferroic behavior in perovskite-related metal-organic frameworks of general formula [(CH(3))(2)NH(2)]M(HCOO)(3), where M = Mn, Fe, Co, and Ni, is reported. All four compounds exhibit paraelectric-antiferroelectric phase transition behavior in the temperature range 160-185 K (Mn: 185 K, Fe: 160 K; Co: 165 K; Ni: 180 K); this is associated with an order-disorder transition involving the hydrogen bonded dimethylammonium cations. On further cooling, the compounds become canted weak ferromagnets below 40 K. This research opens up a new class of multiferroics in which the electrical ordering is achieved by means of hydrogen bonding.

  5. Structire ordering effect on dielectric properties of PbInsub(0.5)Nbsub(0.5)Osub(3) crystals

    International Nuclear Information System (INIS)

    Turik, A.V.; Kupriyanov, M.F.; Zhestkov, B.F.

    1985-01-01

    Results are presented of dielectric and X-ray diffraction investigations into the PbZnsub(0.5)Nbsub(0.5)Osub(3) monocrystals of PbBsub(0.5)'Bsub(0.5)''Osub(3) series (B'=ScIn, B''=Nb, Ta) annealed during 5 hours at 500 deg C. It is shown that ordering in the B'-cation position in crystals influences the character of alternation of phases and physical properties. The PbInsub(0.5)Nbsub(0.5)Osub(3) crystals may be either in rhombohedral ferro- or zhombic antiferroelectric phases depending on thermal prehistory

  6. Development of high performance lubricant through the compatibility of polyalphaolefin, polyurea and irradiated polytetrafluoroethylene; Graxa de poliureia: estudo da compatibilidade da poliureia, polialfaolefina e politetrafluoretileno irradiado para melhoria da lubricidade e estabilidade

    Energy Technology Data Exchange (ETDEWEB)

    Ratao, Natalia Torres

    2013-07-01

    Lubricants are gaseous, liquid, semi solid or solid (powder) materials those form a film between two parties preventing friction. High performance lubricants are designed to work under severe conditions of temperature, pressure, and contamination. The most used are liquids (oils) and semi solids (greases). Greases are applied where oils can drain or in inaccessible places and are divided generally into two classes, soap and no soap. The most used non soap grease is polyurea, obtained by the reaction between amine and isocyanate, has highly thixotropic, high dielectric strength and excellent anticorrosive property, so it is widely used for lubrication of electric motors and shipbuilding machinery. For a grease with high performance, in this study was used a synthetic lubricant fluid, polyalphaolefin, and was also employed solid lubricant additive polytetrafluoroethylene (PTFE) due its lowest coefficient of friction, is found commercially irradiated in air to obtain smaller particles and to produce oxygenated terminal groups those are more compatible with the metal surface. The tests conducted were comparatively between pure polyurea grease and with PTFE additive. The characterizations were made by infrared spectroscopy and elemental analysis of C, N and H and Free NCO index, proving the formation of four carbons polyurea (tetraurea). The functional analysis of drop point and oil separation showed high stability and compatibility between the polymers increased when PTFE was added. The excellent resistance of pure tetraurea grease to wear and extreme pressure were demonstrated by four-ball and practical bearings tests, characterizing this grease as a high performance lubricant, when compared to most used greases in the market. (author)

  7. Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

    Science.gov (United States)

    Li, Qi; Liu, Feihua; Yang, Tiannan; Gadinski, Matthew R.; Zhang, Guangzu; Chen, Long-Qing; Wang, Qing

    2016-01-01

    The demand for a new generation of high-temperature dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite-based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high-temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single-layer configuration, the rationally designed sandwich-structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge–discharge efficiency at elevated temperatures. At 150 °C and 200 MV m−1, an operating condition toward electric vehicle applications, the sandwich-structured polymer nanocomposites outperform the state-of-the-art polymer-based dielectrics in terms of energy density, power density, charge–discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present. PMID:27551101

  8. Thermophysical and radiation properties of high-temperature C4F8-CO2 mixtures to replace SF6 in high-voltage circuit breakers

    Science.gov (United States)

    Zhong, Linlin; Cressault, Yann; Teulet, Philippe

    2018-03-01

    C4F8-CO2 mixtures are one of the potential substitutes to SF6 in high-voltage circuit breakers. However, the arc quenching ability of C4F8-CO2 mixtures is still unknown. In order to provide the necessary basic data for the further investigation of arc quenching performance, the compositions, thermodynamic properties, transport coefficients, and net emission coefficients (NEC) of various C4F8-CO2 mixtures are calculated at temperatures of 300-30 000 K in this work. The thermodynamic properties are presented as the product of mass density and specific heat, i.e., ρCp. The transport coefficients include electrical conductivity, viscosity, and thermal conductivity. The atomic and molecular radiation are both taken into account in the calculation of NEC. The comparison of the properties between SF6 and C4F8-CO2 mixtures is also discussed to find their differences. The results of compositions show that C4F8-CO2 mixtures have a distinctive advantage over other alternative gases e.g., CF3I and C3F8, because the dissociative product (i.e., C4F6) of C4F8 at low temperatures has a very high dielectric strength. This is good for an arc quenching medium to endure the arc recovery phase. Compared with SF6, C4F8-CO2 mixtures present lower ρCp at temperatures below 2800 K and larger thermal conductivity above 2800 K. Based on the position of peaks in thermal conductivity, we predict that the cooling of C4F8-CO2 arc will be slowed down at higher temperatures than that of SF6 arc. It is also found that the mixing of CO2 shows slight effects on the electrical conductivity and NEC of C4F8-CO2 mixtures.

  9. Influence of void defects on partial discharge behavior of superconducting busbar insulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunyu; Huang, Xiongyi, E-mail: huangxy@ipp.ac.cn; Lu, Kun; Li, Guoliang; Zhu, Haisheng; Wang, Jun; Wang, Cao; Dai, Zhiheng; Fang, Linlin; Song, Yuntao

    2017-06-15

    Highlights: • PD detection method was used to check the quality of the superconducting busbar insulation. • The samples with different void fraction were manufactured for comparing. • The discharge inception voltage, PRPD pattern was tested and studied for the samples with different void content. • The PD behaviors in oil bath and air condition were compared. - Abstract: For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

  10. Charge transport in polycrystalline alumina materials: application to the optimization of dielectric breakdown strength; Transport de charges dans les alumines polycristallines: application a l'optimisation de la rigidite dielectrique

    Energy Technology Data Exchange (ETDEWEB)

    Touzin, M.

    2005-12-15

    Dielectric breakdown constitutes an important limitation in the use of insulating materials under high-tension since it leads to the local fusion and the sublimation of material. The microstructure (average grain size, intergranular phase) has a great influence on the ability of material to resist this catastrophic phenomenon. Indeed, the interfaces between the various phases constitute potential sites of trapping for the charges. The optimization of the dielectric breakdown strength of a polycrystalline alumina sintered with a liquid phase passes necessarily through the control of the microstructural parameters. Thus, it is shown that by controlling the conditions of the process (rate of sintering aids, powder grain size and thermal cycle), it is possible to control the density (by the average grain size) but also the nature (by the crystallization or not of anorthite) of the grain boundaries. The study of the influence of these two parameters as well temperature on the properties of charge transport and storage was carried out by methods ICM and SEMME. The results, interpreted in light of the numerical simulation of the charge transport in bulk alumina sample during electron beam irradiation, allowed to highlight behaviors, and the corresponding microstructures, favourable to the dielectric breakdown resistance according to the considered temperature. Thus, at room temperature a high density of interfaces (low grain size and crystallized intergranular phase) makes it possible material to durably trap a great amount of charges, which leads to a high dielectric strength. On the other hand, at higher temperature, the presence of shallow traps (vitreous intergranular phase) supports the charge diffusion and makes it possible to delay breakdown. (author)

  11. Development of high performance lubricant through the compatibility of polyalphaolefin, polyurea and irradiated polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Ratao, Natalia Torres

    2013-01-01

    Lubricants are gaseous, liquid, semi solid or solid (powder) materials those form a film between two parties preventing friction. High performance lubricants are designed to work under severe conditions of temperature, pressure, and contamination. The most used are liquids (oils) and semi solids (greases). Greases are applied where oils can drain or in inaccessible places and are divided generally into two classes, soap and no soap. The most used non soap grease is polyurea, obtained by the reaction between amine and isocyanate, has highly thixotropic, high dielectric strength and excellent anticorrosive property, so it is widely used for lubrication of electric motors and shipbuilding machinery. For a grease with high performance, in this study was used a synthetic lubricant fluid, polyalphaolefin, and was also employed solid lubricant additive polytetrafluoroethylene (PTFE) due its lowest coefficient of friction, is found commercially irradiated in air to obtain smaller particles and to produce oxygenated terminal groups those are more compatible with the metal surface. The tests conducted were comparatively between pure polyurea grease and with PTFE additive. The characterizations were made by infrared spectroscopy and elemental analysis of C, N and H and Free NCO index, proving the formation of four carbons polyurea (tetraurea). The functional analysis of drop point and oil separation showed high stability and compatibility between the polymers increased when PTFE was added. The excellent resistance of pure tetraurea grease to wear and extreme pressure were demonstrated by four-ball and practical bearings tests, characterizing this grease as a high performance lubricant, when compared to most used greases in the market. (author)

  12. Influence of void defects on partial discharge behavior of superconducting busbar insulation

    International Nuclear Information System (INIS)

    Wang, Chunyu; Huang, Xiongyi; Lu, Kun; Li, Guoliang; Zhu, Haisheng; Wang, Jun; Wang, Cao; Dai, Zhiheng; Fang, Linlin; Song, Yuntao

    2017-01-01

    Highlights: • PD detection method was used to check the quality of the superconducting busbar insulation. • The samples with different void fraction were manufactured for comparing. • The discharge inception voltage, PRPD pattern was tested and studied for the samples with different void content. • The PD behaviors in oil bath and air condition were compared. - Abstract: For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

  13. Improved Gate Dielectric Deposition and Enhanced Electrical Stability for Single-Layer MoS2 MOSFET with an AlN Interfacial Layer.

    Science.gov (United States)

    Qian, Qingkai; Li, Baikui; Hua, Mengyuan; Zhang, Zhaofu; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J

    2016-06-09

    Transistors based on MoS2 and other TMDs have been widely studied. The dangling-bond free surface of MoS2 has made the deposition of high-quality high-k dielectrics on MoS2 a challenge. The resulted transistors often suffer from the threshold voltage instability induced by the high density traps near MoS2/dielectric interface or inside the gate dielectric, which is detrimental for the practical applications of MoS2 metal-oxide-semiconductor field-effect transistor (MOSFET). In this work, by using AlN deposited by plasma enhanced atomic layer deposition (PEALD) as an interfacial layer, top-gate dielectrics as thin as 6 nm for single-layer MoS2 transistors are demonstrated. The AlN interfacial layer not only promotes the conformal deposition of high-quality Al2O3 on the dangling-bond free MoS2, but also greatly enhances the electrical stability of the MoS2 transistors. Very small hysteresis (ΔVth) is observed even at large gate biases and high temperatures. The transistor also exhibits a low level of flicker noise, which clearly originates from the Hooge mobility fluctuation instead of the carrier number fluctuation. The observed superior electrical stability of MoS2 transistor is attributed to the low border trap density of the AlN interfacial layer, as well as the small gate leakage and high dielectric strength of AlN/Al2O3 dielectric stack.

  14. An optical sensors for monitoring SF6 dissociation in a corona discharge

    International Nuclear Information System (INIS)

    Irawan, R.; Scelsi, G.B.; Woolsey, G.A.

    1999-01-01

    Sulphur hexafluoride (SF 6 ) is a chemically inert gas (Schumb, 1947) and has high dielectric strength, 3 times greater than air (Morrison and Robins, 1994). In high voltage systems, it is used both as a dielectric and an arc-quenching medium. An electrical breakdown event such as a partial discharge (corona) or arc will dissociate SF 6 into sulphur fluorides, sulphur and fluorine. In a contaminant-free environment, the dissociation products recombine back to SF 6 after extinction of the electrical discharge. Otherwise, some of the products will react with contaminants such as water vapour and oxygen, and with the metal surfaces and electrodes of the discharge chamber, to produce by-products including gaseous sulphur oxyfluorides and solid by-products (Van Brunt, 1985; Griffin et al, 1990 and Vukovic, 1997). As a consequence, a reduction in SF 6 concentration takes place, and the insulating efficiency of the system is degraded. If the SF 6 is not renewed, failure of the high voltage system is likely to eventually occur. One method of monitoring a system is to look for the presence of partial discharges, using techniques such as ultrasonic wave detection (Auckland et al, 1996) or fluorescent plastic fibre (Kurosawa et al., 1997). More directly, the integrity of the SF 6 may be examined using techniques such as mass spectrometry, gas chromatography-mass spectrometry and Fourier Transform Infra-Red Spectroscopy. Such techniques, however, are bulky and require gas samples to be extracted, and so they are unsuited to field use. Since SF 6 insulating systems involve high voltages and a high level of electromagnetic interference, direct in-situ optical monitoring appears to provide the best approach. This paper describes the development of such an optical sensing technique, specifically for continuous monitoring of SF 6 degradation in partial or corona discharges

  15. Research on reliability measures of the main transformer and GIS equipment manufacturing process

    International Nuclear Information System (INIS)

    Wu Honglong

    2014-01-01

    Based on the accidents of the main transformer GIS equipment and the accidents of the high voltage switch equipment, combined with the main transformer switch equipment maintenance experience and electrical theory, the reliability measures of the main transformer GIS equipment during manufacturing stage are studied and improved. Six successful reliability measures are identified: 1) design properly and check the ability of transformer for anti short circuit; 2) choose mature and reliable main transformer HV bushing; 3) choose GIS switch operation mechanism of high quality and reliability; 4) ensure that the insulation margin through tests piece by piece on withstand voltage and partial discharge of the GIS equipment insulation; 5) take test measures such as GIS conductor, shell polishing witness process and full form lightning impulse, to find out and eliminate the defects of abnormal electric field distribution; 6) Anti VFTO design for the main transformer connected with GIS with the voltage of 500 kV should be considered, and its anti VFTO ability to meet the safe operation under VFTO requirements should be checked. This paper proposed 2 new measures: 1) the main transformer insulation material quality standard is determined not only by its high dielectric strength, but more importantly by the homogeneous dielectric electric strength. Insulating Materials with a high and also uniform dielectric strength should be chosen. 2) During the silver-coating stage of the GIS equipment conductor, QC group activities should be organized to ensure that the plating layer quality, and the current lap surface DC resistance measurements should be supervised and witnessed to ensure the quality of the conductor contact surface. These measures are verified in Fuqing project of GIS main transformer equipment manufacturing process, and their effectiveness is proven. (author)

  16. Electrical characteristics of SrTiO{sub 3}/Al{sub 2}O{sub 3} laminated film capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yong; Yao, Manwen, E-mail: yaomw@tongji.edu.cn; Chen, Jianwen; Xu, Kaien; Yao, Xi [Functional Materials Research Laboratory, School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China)

    2016-07-07

    The electrical characteristics of SrTiO{sub 3}/Al{sub 2}O{sub 3} (160 nm up/90 nm down) laminated film capacitors using the sol-gel process have been investigated. SrTiO{sub 3} is a promising and extensively studied high-K dielectric material, but its leakage current property is poor. SrTiO{sub 3}/Al{sub 2}O{sub 3} laminated films can effectively suppress the demerits of pure SrTiO{sub 3} films under low electric field, but the leakage current value reaches to 0.1 A/cm{sup 2} at higher electric field (>160 MV/m). In this study, a new approach was applied to reduce the leakage current and improve the dielectric strength of SrTiO{sub 3}/Al{sub 2}O{sub 3} laminated films. Compared to laminated films with Au top electrodes, dielectric strength of laminated films with Al top electrodes improves from 205 MV/m to 322 MV/m, simultaneously the leakage current maintains the same order of magnitude (10{sup −4} A/cm{sup 2}) until the breakdown occurs. The above electrical characteristics are attributed to the anodic oxidation reaction in origin, which can repair the defects of laminated films at higher electric field. The anodic oxidation reactions have been confirmed by the corresponding XPS measurement and the cross sectional HRTEM analysis. This work provides a new approach to fabricate dielectrics with high dielectric strength and low leakage current.

  17. Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

    International Nuclear Information System (INIS)

    Batishko, C.R.; Brimhall, J.L.; Pawlewicz, W.T.; Stahl, K.A.; Toburen, L.H.

    1987-09-01

    Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 550 0 C. This report summarizes the research and provides a sampling of the data taken during the report period

  18. Electronic structures and abnormal phonon behaviors of cobalt-modified Na0.5Bi0.5TiO3-6%BaTiO3 single crystals

    Science.gov (United States)

    Huang, T.; Zhang, P.; Xu, L. P.; Chen, C.; Zhang, J. Z.; Hu, Z. G.; Luo, H. S.; Chu, J. H.

    2016-10-01

    Optical properties, electronic structures, and structural variations of x wt% cobalt (Co) doped Na0.5Bi0.5TiO3-6%BaTiO3 (x=0%, 0.5%, 0.8%) single crystals have been studied by temperature-dependent optical ellipsometry and Raman spectra from 250 to 650 K. Based on the temperature evolution of electronic transitions (Ecp1 and Ecp2) and the phonon modes involving Ti-O vibrations, two critical temperature points exhibit an increasing trend with Co dopants, which are related to structural variations for ferroelectric to anti-ferroelectric, and anti-ferroelectric to paraelectric transition, respectively. Additionally, distinguishing abnormal phonon behaviors can be observed from Raman spectra for the crystal of x=0.5% and 0.8%, which show reverse frequency shift of the modes involving Ti-O vibration. It can be ascribed to different relative concentration of Co2+ and Co3+ in the crystals, which has been confirmed by X-ray Photoelectron Spectroscopy data.

  19. Electronic structures and abnormal phonon behaviors of cobalt-modified Na0.5Bi0.5TiO3-6%BaTiO3 single crystals

    Directory of Open Access Journals (Sweden)

    T. Huang

    2016-10-01

    Full Text Available Optical properties, electronic structures, and structural variations of x wt% cobalt (Co doped Na0.5Bi0.5TiO3-6%BaTiO3 (x=0%, 0.5%, 0.8% single crystals have been studied by temperature-dependent optical ellipsometry and Raman spectra from 250 to 650 K. Based on the temperature evolution of electronic transitions (Ecp1 and Ecp2 and the phonon modes involving Ti-O vibrations, two critical temperature points exhibit an increasing trend with Co dopants, which are related to structural variations for ferroelectric to anti-ferroelectric, and anti-ferroelectric to paraelectric transition, respectively. Additionally, distinguishing abnormal phonon behaviors can be observed from Raman spectra for the crystal of x=0.5% and 0.8%, which show reverse frequency shift of the modes involving Ti-O vibration. It can be ascribed to different relative concentration of Co2+ and Co3+ in the crystals, which has been confirmed by X-ray Photoelectron Spectroscopy data.

  20. Effect of the annealing temperature of thin Hf0.3Zr0.7O2 films on their energy storage behavior

    International Nuclear Information System (INIS)

    Park, Min Hyuk; Kim, Han Joon; Kim, Yu Jin; Moon, Taehwan; Kim, Keum Do; Hwang, Cheol Seong

    2014-01-01

    With increasing annealing temperature (T anneal ), the magnitude of the electric fields for the antiferroelectric-to-ferro-electric (E AF ) and ferroelectric-to-antiferroelectric (E FA ) transition of a 9.2 nm thick Hf 0.3 Zr 0.7 O 2 film decreased. The energy storage densities of the Hf 0.3 Zr 0.7 O 2 films crystallized at 400 C, 500 C, and 600 C were as large as 42.2 J/cm 3 , 40.4 J/cm 3 , and 28.3 J/cm 3 , respectively, at the electric field of 4.35 MV/cm. The maximum dielectric constant of the Hf 0.3 Zr 0.7 O 2 film crystallized at 600 C was the largest (∝46) as it had the smallest E AF and E FA , whereas the leakage current density of the film crystallized at 400 C was the smallest. The 400 C of T anneal was the optimum condition for energy storage application. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Study of crystal structure and of dynamic behaviour in the various phases of TlD{sub 2}PO{sub 4}; Etude de la structure cristalline et du comportement dynamique dans les differentes phases de TlD{sub 2}PO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Rios, S

    1997-04-29

    TlH2PO4 (TDP) and its deuterated form TlD2PO4 (DTDP) belong to the family of ferroelectric materials of KH2PO4 (KDP). The compounds of this family, on deuteration, show a large isotopic effect in their ferroelectric transition temperatures. This work begins with a review of theoretical models which allowed a better understanding of the antiferroelectric transition. The crystal structures of TDP and DTDP have been studied at different temperatures, using single-crystal neutron diffraction and the results show that the phase diagrams for both compounds have very different characteristics. The dynamics of antiferroelectric transition of DTDP has been investigated by means of neutron inelastic scattering. Supported by these experimental results we propose a mechanism to explain the different phase sequences in these compounds. In the last part of this work a more qualitative study suggests that the effect of deuteration could be seen as a pressure effect. This result has to be confirmed by using a more appropriate means of investigation than neutron scattering. (A.C.) 61 refs.

  2. Study of crystal structure and of dynamic behaviour in the various phases of TlD2PO4

    International Nuclear Information System (INIS)

    Rios, S.

    1997-01-01

    TlH2PO4 (TDP) and its deuterated form TlD2PO4 (DTDP) belong to the family of ferroelectric materials of KH2PO4 (KDP). The compounds of this family, on deuteration, show a large isotopic effect in their ferroelectric transition temperatures. This work begins with a review of theoretical models which allowed a better understanding of the antiferroelectric transition. The crystal structures of TDP and DTDP have been studied at different temperatures, using single-crystal neutron diffraction and the results show that the phase diagrams for both compounds have very different characteristics. The dynamics of antiferroelectric transition of DTDP has been investigated by means of neutron inelastic scattering. Supported by these experimental results we propose a mechanism to explain the different phase sequences in these compounds. In the last part of this work a more qualitative study suggests that the effect of deuteration could be seen as a pressure effect. This result has to be confirmed by using a more appropriate means of investigation than neutron scattering. (A.C.)

  3. Characterisation of lead barium zirconate thin films for utilisation of the electrocaloric effect

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, C.P., E-mail: c.p.shaw@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Zhang, Qi, E-mail: q.zhang@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Correia, T.M., E-mail: Tatiana.correia@ktn-uk.org [Knowledge Transfer Network (United Kingdom); Weaver, P.M., E-mail: paul.weaver@innotecuk.com [InotekUK (United Kingdom)

    2016-08-01

    Characterisation of a composition of Lead Barium Zirconate thin films deposited by a spin coating sol-gel process onto platinised silicon substrates has been undertaken to investigate a potential application utilising the reported electrocaloric properties of the material. Xray diffraction studies revealed that above 700 °C the presence of pyrochlore phase was replaced by ferroelectric phase but the identification of antiferroelectric phases previously reported could not be identified. Wet etching of the films produced an insoluble residue containing only evidence of zirconium out of the original three metals, which resembled a skeletal structure similar to the original rosette morphology of the annealed films. Elemental analysis of the annealed films using EDX indicated a non-target Pb:Ba:Zr ratio, which suggested a reduced Zr content of the films. “Solution-like” rather than “sol-like” nature of the spin coated sol and phase boundary proximity are proposed for reported observations, and a mechanism is proposed to account for the unusual observed trend in dielectric constant. - Highlights: • Characterisation of sol-gel deposited Lead barium zirconnate films. • Absence of previously reported antiferroelectric phase. • Identification of proposed non-PBZ phase. • Anomalous increase in film capacitance with thickness interpreted.

  4. Heterogeneous contribution of microdeletions in the development of common generalised and focal epilepsies

    Science.gov (United States)

    Pérez-Palma, Eduardo; Helbig, Ingo; Klein, Karl Martin; Anttila, Verneri; Horn, Heiko; Reinthaler, Eva Maria; Gormley, Padhraig; Ganna, Andrea; Byrnes, Andrea; Pernhorst, Katharina; Toliat, Mohammad R; Saarentaus, Elmo; Howrigan, Daniel P; Hoffman, Per; Miquel, Juan Francisco; De Ferrari, Giancarlo V; Nürnberg, Peter; Lerche, Holger; Zimprich, Fritz; Neubauer, Bern A; Becker, Albert J; Rosenow, Felix; Perucca, Emilio; Zara, Federico; Weber, Yvonne G; Lal, Dennis

    2017-01-01

    Background Microdeletions are known to confer risk to epilepsy, particularly at genomic rearrangement ‘hotspot’ loci. However, microdeletion burden not overlapping these regions or within different epilepsy subtypes has not been ascertained. Objective To decipher the role of microdeletions outside hotspots loci and risk assessment by epilepsy subtype. Methods We assessed the burden, frequency and genomic content of rare, large microdeletions found in a previously published cohort of 1366 patients with genetic generalised epilepsy (GGE) in addition to two sets of additional unpublished genome-wide microdeletions found in 281 patients with rolandic epilepsy (RE) and 807 patients with adult focal epilepsy (AFE), totalling 2454 cases. Microdeletions were assessed in a combined and subtype-specific approaches against 6746 controls. Results When hotspots are considered, we detected an enrichment of microdeletions in the combined epilepsy analysis (adjusted p=1.06×10−6,OR 1.89, 95% CI 1.51 to 2.35). Epilepsy subtype-specific analyses showed that hotspot microdeletions in the GGE subgroup contribute most of the overall signal (adjusted p=9.79×10−12, OR 7.45, 95% CI 4.20–13.5). Outside hotspots , microdeletions were enriched in the GGE cohort for neurodevelopmental genes (adjusted p=9.13×10−3,OR 2.85, 95% CI 1.62–4.94). No additional signal was observed for RE and AFE. Still, gene-content analysis identified known (NRXN1, RBFOX1 and PCDH7) and novel (LOC102723362) candidate genes across epilepsy subtypes that were not deleted in controls. Conclusions Our results show a heterogeneous effect of recurrent and non-recurrent microdeletions as part of the genetic architecture of GGE and a minor contribution in the aetiology of RE and AFE. PMID:28756411

  5. An Inductively-Powered Wireless Neural Recording System with a Charge Sampling Analog Front-End.

    Science.gov (United States)

    Lee, Seung Bae; Lee, Byunghun; Kiani, Mehdi; Mahmoudi, Babak; Gross, Robert; Ghovanloo, Maysam

    2016-01-15

    An inductively-powered wireless integrated neural recording system (WINeR-7) is presented for wireless and battery less neural recording from freely-behaving animal subjects inside a wirelessly-powered standard homecage. The WINeR-7 system employs a novel wide-swing dual slope charge sampling (DSCS) analog front-end (AFE) architecture, which performs amplification, filtering, sampling, and analog-to-time conversion (ATC) with minimal interference and small amount of power. The output of the DSCS-AFE produces a pseudo-digital pulse width modulated (PWM) signal. A circular shift register (CSR) time division multiplexes (TDM) the PWM pulses to create a TDM-PWM signal, which is fed into an on-chip 915 MHz transmitter (Tx). The AFE and Tx are supplied at 1.8 V and 4.2 V, respectively, by a power management block, which includes a high efficiency active rectifier and automatic resonance tuning (ART), operating at 13.56 MHz. The 8-ch system-on-a-chip (SoC) was fabricated in a 0.35-μm CMOS process, occupying 5.0 × 2.5 mm 2 and consumed 51.4 mW. For each channel, the sampling rate is 21.48 kHz and the power consumption is 19.3 μW. In vivo experiments were conducted on freely behaving rats in an energized homecage by continuously delivering 51.4 mW to the WINeR-7 system in a closed-loop fashion and recording local field potentials (LFP).

  6. Heterogeneous contribution of microdeletions in the development of common generalised and focal epilepsies.

    Science.gov (United States)

    Pérez-Palma, Eduardo; Helbig, Ingo; Klein, Karl Martin; Anttila, Verneri; Horn, Heiko; Reinthaler, Eva Maria; Gormley, Padhraig; Ganna, Andrea; Byrnes, Andrea; Pernhorst, Katharina; Toliat, Mohammad R; Saarentaus, Elmo; Howrigan, Daniel P; Hoffman, Per; Miquel, Juan Francisco; De Ferrari, Giancarlo V; Nürnberg, Peter; Lerche, Holger; Zimprich, Fritz; Neubauer, Bern A; Becker, Albert J; Rosenow, Felix; Perucca, Emilio; Zara, Federico; Weber, Yvonne G; Lal, Dennis

    2017-09-01

    Microdeletions are known to confer risk to epilepsy, particularly at genomic rearrangement 'hotspot' loci. However, microdeletion burden not overlapping these regions or within different epilepsy subtypes has not been ascertained. To decipher the role of microdeletions outside hotspots loci and risk assessment by epilepsy subtype. We assessed the burden, frequency and genomic content of rare, large microdeletions found in a previously published cohort of 1366 patients with genetic generalised epilepsy (GGE) in addition to two sets of additional unpublished genome-wide microdeletions found in 281 patients with rolandic epilepsy (RE) and 807 patients with adult focal epilepsy (AFE), totalling 2454 cases. Microdeletions were assessed in a combined and subtype-specific approaches against 6746 controls. When hotspots are considered, we detected an enrichment of microdeletions in the combined epilepsy analysis (adjusted p=1.06×10 -6 ,OR 1.89, 95% CI 1.51 to 2.35). Epilepsy subtype-specific analyses showed that hotspot microdeletions in the GGE subgroup contribute most of the overall signal (adjusted p=9.79×10 -12 , OR 7.45, 95% CI 4.20-13.5). Outside hotspots , microdeletions were enriched in the GGE cohort for neurodevelopmental genes (adjusted p=9.13×10 -3 ,OR 2.85, 95% CI 1.62-4.94). No additional signal was observed for RE and AFE. Still, gene-content analysis identified known ( NRXN1 , RBFOX1 and PCDH7 ) and novel ( LOC102723362 ) candidate genes across epilepsy subtypes that were not deleted in controls. Our results show a heterogeneous effect of recurrent and non-recurrent microdeletions as part of the genetic architecture of GGE and a minor contribution in the aetiology of RE and AFE. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  7. Effect of doping and chemical ordering on the optoelectronic properties of complex oxides: Fe 2 O 3 –V 2 O 3 solid solutions and hetero-structures

    Energy Technology Data Exchange (ETDEWEB)

    Nayyar, Iffat H.; Chamberlin, Sara E.; Kaspar, Tiffany C.; Govind, Niranjan; Chambers, Scott A.; Sushko, Petr

    2017-01-01

    The electronic and optical properties of a-(Fe1xVx)2O3 at low (x = 0.04) and high (x = 0.5) doping levels are investigated using a combination of periodic and embedded cluster approaches, and time dependent density functional theory. At low V concentrations the onset of the optical absorption is B0.5 eV (i.e., nearly 1.6 eV lower than that in pure a-Fe2O3) and corresponds to the electron transitions from V 3d to Fe 3d* orbitals. At high V concentrations, optical absorption energies and intensities are sensitive to specific arrangements of Fe and V atoms and their spin configuration that determine Fe–V hybridization. The onset of the lowest inter-vanadium absorption band in the case of Fe2O3/V2O3 hetero-structures is as low as B0.3 eV and the corresponding peak is at B0.7 eV. In contrast, in the case of solid solutions this peak has lower intensity and is shifted to higher energy (B1.2 eV). Analysis of the orbital character of electronic excitation suggests that Fe2O3/V2O3 hetero-structures absorb light much more effectively than random alloys, thus promoting efficient photo-induced carrier generation. These predictions can be tested in a-(Fe1xVx)2O3 thin films synthesized with well-controlled spatial distribution of Fe and V species.

  8. Fuel consumption from vehicles of China until 2030 in energy scenarios

    International Nuclear Information System (INIS)

    Zhang Qingyu; Tian Weili; Zheng Yingyue; Zhang Lili

    2010-01-01

    Estimation of fuel (gasoline and diesel) consumption for vehicles in China under different long-term energy policy scenarios is presented here. The fuel economy of different vehicle types is subject to variation of government regulations; hence the fuel consumption of passenger cars (PCs), light trucks (Lts), heavy trucks (Hts), buses and motor cycles (MCs) are calculated with respect to (i) the number of vehicles, (ii) distance traveled, and (iii) fuel economy. On the other hand, the consumption rate of alternative energy sources (i.e. ethanol, methanol, biomass-diesel and CNG) is not evaluated here. The number of vehicles is evaluated using the economic elastic coefficient method, relating to per capita gross domestic product (GDP) from 1997 to 2007. The Long-range Energy Alternatives Planning (LEAP) system software is employed to develop a simple model to project fuel consumption in China until 2030 under these scenarios. Three energy consumption decrease scenarios are designed to estimate the reduction of fuel consumption: (i) 'business as usual' (BAU); (ii) 'advanced fuel economy' (AFE); and (iii) 'alternative energy replacement' (AER). It is shown that fuel consumption is predicted to reach 992.28 Mtoe (million tons oil equivalent) with the BAU scenario by 2030. In the AFE and AER scenarios, fuel consumption is predicted to be 734.68 and 600.36 Mtoe, respectively, by 2030. In the AER scenario, fuel consumption in 2030 will be reduced by 391.92 (39.50%) and 134.29 (18.28%) Mtoe in comparison to the BAU and AFE scenarios, respectively. In conclusion, our models indicate that the energy conservation policies introduced by governmental institutions are potentially viable, as long as they are effectively implemented.

  9. Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes

    Science.gov (United States)

    Sedach, Pavel Anatolyvich

    The direct conversion of sunlight into more useable forms of energy has the potential of alleviating the environmental and social problems associated with a dependence on fossil fuels. If solar energy is to be utilized en-masse, however, it must be inexpensive and widely available. In this vein, the focus of this thesis is on nanostructured materials relevant to solar energy conversion and storage. Specifically, this thesis describes the ambient sol-gel synthesis of titanium dioxide (Ti02) nanowires designed for enhanced charge-transfer in solar collection devices, and the synthesis of novel disordered metal-oxide (MOx) catalysts for water oxidation. The introductory chapter of this thesis gives an overview of the various approaches to solar energy conversion. Sol---gel reaction conditions that enable the growth of one-dimensional (1-D) anatase TiO2 nanostructures from fluorine-doped tin oxide (FTO) for photovoltaics (PVs) are described in the second chapter. The generation of these linear nanostructures in the absence of an external bias or template is achieved by using facile experimental conditions (e.g., acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane). The procedure was developed by functionalizing base-treated substrates with Ti-oxide nucleation sites that serve as a foundation for the growth of linear Ti-oxide macromolecules, which upon calcination, render uniform films of randomly oriented anatase TiO2 nanowires. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO 2 films is presented. A photo-organic MO. deposition route (i.e., photochemical metal-organic deposition (PMOD)) used to deposit thin-films of amorphous iron oxide (a-Fe2O3) for water oxidation catalysis is detailed in third chapter. It is shown that the irradiation of a spin-coated metal-organic film produces a film of non-crystalline a-Fe203. It is shown

  10. Nanoparticles of spinel and perovskite ferromagnets and prospects for their application in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Belous, A. G., E-mail: belous@ionc.kar.net, E-mail: solopan@ukr.net, E-mail: yelenicho@ukr.net; Solopan, S. O., E-mail: belous@ionc.kar.net, E-mail: solopan@ukr.net, E-mail: yelenicho@ukr.net; Yelenich, O. V., E-mail: belous@ionc.kar.net, E-mail: solopan@ukr.net, E-mail: yelenicho@ukr.net [Institute of General and Inorganic Chemistry, prospekt Palladina 32-34, 03142 Kyiv (Ukraine); Tovstolytkin, A. I., E-mail: atov@imag.kiev.ua [Institute of Magnetism, bulvar Vernadskoho 36-b, 03142 Kyiv (Ukraine); Kolodiazhnyi, T. V., E-mail: kolodiazhnyi.taras@nims.go.jp [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Osinsky, S. P., E-mail: osion@onconet.kiev.ua, E-mail: bybnovskayal@ukr.net; Bubnovskaya, L. N., E-mail: osion@onconet.kiev.ua, E-mail: bybnovskayal@ukr.net [R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, vul. Vasylkivska 45, 03022 Kyiv (Ukraine)

    2014-11-05

    In this work, nanoparticles of La{sub 0.75}Sr{sub 0.25}MnO{sub 3} compounds with perovskite structure and AFe{sub 2}O{sub 4} (A = Mn, Fe, Co, Ni, Zn) with spinel structure have been synthesized by precipitation from diethylene glycol and microemulsion using Triton X-100 surfactant. Comparative X-ray diffraction and magnetic studies of the synthesized nanoparticles have been carried out. Magnetic fluids prepared from synthesized nanopowders have been characterized by calorimetric measurements of specific loss power (SLP)

  11. Competing Auctions of Skills

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Daniel

    We generalize McAfee’s (1993) game of competing sellers to the case of heterogeneous sellers. In the generalized McAfee (GM) game, the equilibrium expected job offer distribution of each worker (seller) type evolves over time as a function of stochastic events. We derive a tractable method...... of solving the GM game. We estimate, using non-parametric methods, a close fit between a benchmark GM game and a cross-section of Danish data on productivity and unemployment. The theoretical properties of the GM game, which relate to on-the-job search, assortative matching, aggregate and match specific...

  12. Clinical Investigation Program. Annual Research Progress Report.

    Science.gov (United States)

    1980-09-30

    protocol H , .. . . .. . . .. Department of Pediactics - continued Way, G.L., Pierce, J.R., Wolfe, R.R., McGrath, R., Merenstein, G.B.: ST Depression ...Tg F3 aiIitLY : FjxMC N. J. MARTIN, MD, MAJ, MIC -) et / Se c: HEM-ONC, Medicine (10) -Assoc Invc2stigators,: (Mi Key Words: 5FU , Ascorbic tcid WILSON...range of mouse death. This was 75,000 cell/ CU.1m. In ac~dition to this, the maximum s:afe dlose range for 5FU was established in the BFI)1 hybrid

  13. Bangor International/Dow AFB, Maine. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

    Science.gov (United States)

    1981-11-06

    temporary site at ground GM1-1l RO-2 Surfac level in ramp area. 6 Apr 60 Located approx 200 ft from corner Same RO-2A 13 ft of old rnwy 33 taxiway and...USAF STAC . 0-14-S( OL A) ............ . . .T... ..O . PORN ... 17- GLCPAL CLIMATOLOGY 9RANCH ArETAC CEILING VERSUS VISIBILITY Alq WEATHEk SERVICL/4AC S...13.1 i ?6 6.. 5918 USAFETAC PORN 0.9.5 (OL.-) PFVIOUS EDITIONS OF TnIS FORM AIRE ORSOLTE Jut 64 GLCRAL CLIMAT0L.i Y 1 ANCH AFE T AC SKYCO E A>4 4ATHER

  14. Pressure-driven phase transitions in TiOCl and the family (Ca, Sr, Ba)Fe2As2

    International Nuclear Information System (INIS)

    Zhang YuZhong; Opahle, Ingo; Jeschke, Harald O; ValentI, Roser

    2010-01-01

    Motivated by recent experimental measurements on pressure-driven phase transitions in Mott insulators as well as the new iron pnictide superconductors, we show that first principles Car-Parrinello molecular dynamics calculations are a powerful method to describe the microscopic origin of such transitions. We present results for (i) the pressure-induced insulator to metal phase transition in the prototypical Mott insulator TiOCl as well as (ii) the pressure-induced structural and magnetic phase transitions in the family of correlated metals AFe 2 As 2 (A = Ca, Sr, Ba). Comparison of our predictions with existing experimental results yields very good agreement.

  15. Evaluación exergética de la calidad del agua de tres ríos en Colombia

    OpenAIRE

    Bastidas Alzate, Mary Loly

    2014-01-01

    Resumen: La exergia es una forma de energía libre que se fundamenta en la segunda Ley de la termodinámica y que se puede utilizar para evaluar el impacto causado sobre los recursos naturales. En esta investigación se tomaron los datos de monitoreo de las corporaciones autónomas regionales de Colombia: CVC, Corpocaldas y Corpoboyacá, para calcular la exergía química, en sesenta estaciones de monitoreo de los ríos Cauca, Chinchiná y Lengupá. Se identificó donde se presentan las mayores afe...

  16. Spin-wave excitation and Moessbauer spectrometry of amorphous interface in Tb/Fe multilayer

    International Nuclear Information System (INIS)

    El Khiraoui, S.; Sajieddine, M.; Lassri, H.; Sahlaoui, M.

    2009-01-01

    Magnetic properties of Tb(48 A)/Fe(26 A) multilayer were studied with Moessbauer spectrometry at different temperatures before and after isothermal annealing at 673 K. For this last case, a significant perpendicular magnetic anisotropy is induced. This phenomenon is related to the existence of an amorphous and homogenous Tb-Fe alloy, located at the interfaces, which is produced by interdiffusion during the heat processing. The thermal evolution of hyperfine field deduced for interfacial Tb-Fe alloy is found to obey the Bloch law. The spin-wave stiffness constant, the distance between nearest magnetic atoms and the exchange parameter A were calculated from the experimental results

  17. Psychometric properties of the Attitudes Scale facing Alcohol and Alcoholism in nursing students.

    Science.gov (United States)

    Vargas, Divane de; Rocha, Fernanda Mota

    2016-12-19

    to verify the psychometric properties of the Attitudes Scale facing Alcohol and Alcoholism (EAFAA) and people with disorders related to the use of alcohol in nursing students. a convenience sample (n=420) completed the EAFAA, the data were submitted to Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). the EFA resulted in an instrument composed of 48 items divided into four factors. The CFA has established the validity of the factorial structure. The internal consistency of the scale was considered adequate (α=0.85) presenting a sensitivity of 70% and specificity of 75%. the EAFAA constitutes a reliable instrument to identify the attitudes of nursing students towards alcohol, alcoholism and persons with disorders related to alcohol use. verificar as propriedades psicométricas da Escala de Atitudes Frente ao Álcool, ao Alcoolismo e as pessoas com transtornos relacionados ao uso do Álcool em estudantes de enfermagem. uma amostra de conveniência (n=420) completou a EAFAA, os dados foram submetidos à Análise Fatorial Exploratória (AFE) e Análise Fatorial Confirmatória (AFC). a AFE resultou em um instrumento composto por 48 itens divididos em quatro fatores. A AFC estabeleceu a validade da estrutura fatorial. A consistência interna da escala foi considerada adequada (α=0,85) apresentando sensibilidade de 70% e especificidade de 75%. a EAFAA constitui-se em um instrumento confiável para identificar as atitudes de estudantes de enfermagem frente ao álcool, ao alcoolismo e a pessoa com transtornos relacionados ao uso de álcool. verificar las propiedades psicométricas de la escala de actitudes frente al alcohol, al alcoholismo y a las personas con trastornos por consumo de alcohol en estudiantes de enfermería. una muestra por conveniencia (n=420) completó la EAFAA, cuyos datos se sometieron a un análisis factorial exploratorio (AFE) y un análisis factorial confirmatorio (AFC). el AFE dio como resultado un instrumento compuesto por

  18. El Laboratorio Clínico y el Dengue

    OpenAIRE

    Gilberto Angel M.

    1990-01-01

    El dengue es una enfermedad endémica de zonas tropicales y subtropicales, en regiones que se encuentran por debajo de los 1.800 metros sobre el nivel del mar.

    En 1969 se registraron varios brotes en el Caribe, Puerto Rico e Islas Vírgenes y en 1970 se diagnosticó en Barranquilla. En !975 se encontraron en el Magdalena medio unos 450 casos. En 1979 se señalaron unos 3.000 casos en México y en 1981 se padeció en Cuba una gran epidemia de dengue clásico tipo 1, que afe...

  19. Valoración de impacto ambiental en el Puerto Moa-Holguín

    OpenAIRE

    Guilarte, A; Díaz, A; Nápoles, J; Fernández, O; Abalos, A; Pérez, R.M

    2015-01-01

    Las operaciones de descarga de los buques-tanques, la recepción y distribución de productos derivados del crudo de petróleo en el área de almacenamiento, el movimiento de insumos como el carbón antracita, amoniaco y azufre, la carga de lotes de minerales así como el mantenimiento de los tanques, conducen al vertimiento directo de hidrocarburos que afectan los diferentes ecosistemas en los cuales se encuentra situada la fuente contaminante. Se presenta la caracterización de los ecosistemas afe...

  20. Acercamiento clínico y tratamiento nutricional a la diabetes mellitus 2

    OpenAIRE

    Córdova Soria, Luis Miguel; Solís Sánchez, Carlos Alberto

    2013-01-01

    El presente trabajo es una revisión bibliográfica de diversas investigaciones con relación a la Diabetes Mellitus 2, que es una Enfermedad Crónica No Transmisible de alta prevalencia a nivel mundial y en el Ecuador. Es una de las principales causas de mortalidad, no por la diabetes per se, sino más bien por las enfermedades relacionadas y que se producen como consecuencia o degeneración de la Diabetes Mellitus 2 debido a la edad o por un mal manejo de la enfermedad por parte de la persona afe...

  1. Persistent Fe moments in the normal-state collapsed-tetragonal phase of the pressure-induced superconductor Ca0.67Sr0.33Fe2As2

    Science.gov (United States)

    Jeffries, J. R.; Butch, N. P.; Lipp, M. J.; Bradley, J. A.; Kirshenbaum, K.; Saha, S. R.; Paglione, J.; Kenney-Benson, C.; Xiao, Y.; Chow, P.; Evans, W. J.

    2014-10-01

    Using nonresonant Fe Kβ x-ray emission spectroscopy, we reveal that Sr substitution into CaFe2As2 decouples the Fe moment from the volume collapse transition, yielding a collapsed-tetragonal, paramagnetic normal state out of which superconductivity develops. X-ray diffraction measurements implicate the c-axis lattice parameter as the controlling criterion for the Fe moment, promoting a generic description for the appearance of pressure-induced superconductivity in the alkaline-earth-based 122 ferropnictides (AFe2As2). The evolution of Tc with pressure lends support to theories for superconductivity involving unconventional pairing mediated by magnetic fluctuations.

  2. Enfermería y enfermedades psicosomáticas relacionadas con el estrés

    OpenAIRE

    Hernández Sánchez, Judit

    2012-01-01

    trabajo que a continuación vamos a desarrollar consiste en una revisión documental acerca de uno de los temas más frecuentes en el área de la salud mental, y más en concreto en el campo de las afecciones psico lógicas: las enfermedades psicosomáticas. Nos centraremos especialmente en una de estas afe cciones psicológicas: el estrés, por ser una de las patologías que cada vez con mayor frecuencia aparece en la consulta médica.

  3. ¿Energía incluyente? Expectativas de participación en el Chile de hoy

    OpenAIRE

    Marco Billi

    2016-01-01

    Desde el punto de vista sociopolítico, la distinción de igualdad/ desigualdad se relaciona estrechamente con la de inclusión/ exclusión: así, las desigualdades inherentes en los problemas socioambientales pueden ser vistas, a la vez, como problemas de inclusión: inclusión en el espacio de la decisión, inclusión en el espacio de los afectados, inclusión en el espacio de los compensados. La multiplicación de movimientos de protesta dirigidos a visibilizar estas desigualdades e incluir a los afe...

  4. Dermatologia veterinária em animais de companhia

    OpenAIRE

    Pinho, Renato Martins

    2015-01-01

    Dissertação de Mestrado Integrado em Medicina Veterinária, Ciências Veterinárias A Dermatologia, em Medicina Veterinária, é uma área que representa entre 25 a 30% do total de consultas em animais de companhia, apresentando uma relação de proximidade crescente em relação à medicina humana. O presente trabalho teve como objetivos principais os seguintes estudos de caso: 1) Determinação da incidência de afeções dermatológicas e caracterização dos animais admitidos à consulta de especialida...

  5. Histologia e fisiologia da dor de origem pulpar

    OpenAIRE

    Fernandes, Bruno Miguel Oliveira

    2015-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Na prática clínica dentária é comum observar que um grande número de pacientes que solicitam uma consulta sem agendamento se deve a uma urgência ou emergência. Normalmente, esses pacientes chegam de maneira inesperada e com dores severas, alterando a rotina da agenda do dentista e, simultaneamente, criando situações de tensão que afe...

  6. La relación entre satisfacción laboral, compromiso organizacional e intención de rotación en profesionales de una empresa minera en el Perú

    OpenAIRE

    Cainicela Ramírez, Fiorella Johanna; Pazos Egúsquiza, Patricia Juliana

    2016-01-01

    La investigación tiene como objetivo identificar si existe relación entre la satisfacción laboral, el compromiso organizacional y la intención de rotación en profesionales de una empresa minera. Así como, determinar las variables que predicen la intención de rotación. Para ello, fueron encuestados 150 profesionales, considerando la variable de satisfacción laboral con sus dos factores (extrínsecos e intrínsecos), la variable de compromiso organizacional en sus tres dimensiones (compromiso afe...

  7. Air data system optimization using a genetic algorithm

    Science.gov (United States)

    Deshpande, Samir M.; Kumar, Renjith R.; Seywald, Hans; Siemers, Paul M., III

    1992-01-01

    An optimization method for flush-orifice air data system design has been developed using the Genetic Algorithm approach. The optimization of the orifice array minimizes the effect of normally distributed random noise in the pressure readings on the calculation of air data parameters, namely, angle of attack, sideslip angle and freestream dynamic pressure. The optimization method is applied to the design of Pressure Distribution/Air Data System experiment (PD/ADS) proposed for inclusion in the Aeroassist Flight Experiment (AFE). Results obtained by the Genetic Algorithm method are compared to the results obtained by conventional gradient search method.

  8. Factores relacionados con el éxito del mantenimiento productivo total

    Directory of Open Access Journals (Sweden)

    Jorge Luis García Alcaraz

    2011-01-01

    Full Text Available El mantenimiento productivo total (TPM es una herramienta ampliamente usada en las áreas productivas, encaminada a incrementar la disponibilidad de la maquinaria y equipo de producción y los beneficios económicos de las empresas. Sin embargo, no se conocen los factores administrativos que aseguren su éxito de implantación. En este artículo se presentan los resultados de una encuesta que constó de 20 ítems y fue aplicada a 203 gerentes y supervisores de mantenimiento de empresas localizadas en Ciudad Juárez, la cual debía ser respondida en una escala Likert. El cuestionario se validó mediante el índice Alfa de Cronbach, se aplicó un análisis factorial exploratorio (AFE mediante el método de componentes principales y se realizó una rotación Varimax y se determinó que solamente 3 factores podían explicar el 65,06% de la varianza total, los cuales estaban relacionados con el compromiso de la gerencia, la cultura de limpieza e integración de operadores en decisiones de TPM. Además, se realizó un análisis factorial confirmatorio (AFC para validar los resultados obtenidos, confirmándose los hallazgos del AFE.

  9. Spectral estimation for long-term evolution transceivers using low-complex filter banks

    Directory of Open Access Journals (Sweden)

    Thomas Schlechter

    2014-06-01

    Full Text Available For mobile user equipments (UEs, a careful power management is essential. Despite this fact, quite an amount of energy is wasted in today's UEs’ analogue (AFEs and digital frontends (DFEs. These are engineered for extracting the wanted signal from a spectral environment defined in the corresponding communication standards with their extremely tough requirements. These requirements define a worst-case scenario still ensuring reliable communication. In a typical receiving process the actual requirements can be considered as less critical. Knowledge about the actual environmental spectral conditions allows to reconfigure both frontends to the actual needs and to save energy. In this paper, the authors present a highly efficient generic spectrum sensing approach, which allows to collect information about the actual spectral environment of an UE. This information can be used to reconfigure both the AFE and DFE, thus endowing them with increased intelligence. A low-complex multiplier free filter bank extended by an efficient power calculation unit will be introduced. They also present simulation results, which illustrate the performance of the spectrum sensing approach and a complexity comparison with different well-known implementations is given. Furthermore, estimates on the chip area and power consumption based on a 65 nm CMOS technology database are provided, considering the Smarti4G chip as a reference.

  10. Theoretical investigation of non-equilibrium chemistry and optical radiation in hypersonic flow fields

    Science.gov (United States)

    Whiting, Ellis E.

    1990-01-01

    Future space vehicles returning from distant missions or high earth orbits may enter the upper regions of the atmosphere and use aerodynamic drag to reduce their velocity before they skip out of the atmosphere and enter low earth orbit. The Aeroassist Flight Experiment (AFE) is designed to explore the special problems encountered in such entries. A computer code was developed to calculate the radiative transport along line-or-sight in the general 3-D flow field about an arbitrary entry vehicle, if the temperatures and species concentrations along the line-of-sight are known. The radiative heating calculation at the stagnation point of the AFE vehicle along the entry trajectory was performed, including a detailed line-by-line accounting of the radiative transport in the vacuum ultraviolet (below 200 nm) by the atomic N and O lines. A method was developed for making measurements of the haze particles in the Titan atmosphere above 200 km altitude. Several other tasks of a continuing nature, to improve the technical ability to calculate the nonequilibrium gas dynamic flow field and radiative heating of entry vehicles, were completed or advanced.

  11. Status report on front end electronics for the EUSO photon detector

    International Nuclear Information System (INIS)

    Bosson, G.; Dzahini, D.; Koang, D.H.; Musico, P.; Pallavicini, M.; Pouxe, J.; Pratolongo, F.; Richer, J.P.

    2002-01-01

    In this paper we'll give a status report on the design of the front end electronic system which will be used for the EUSO photon detector. For space, mass and power consumption constraints the system will be implemented developing an ASIC chip using a deep submicron technology. Two complementary approaches will be described: a digital one (DFEE) and an analog one (AFEE). The DFEE is able to count the single photoelectrons coming form the detector, store the numbers in a memory buffer and read them out after a trigger using a serial communication line. The AFEE integrate the anode signals, store them in an analog memory and serially send all the values to a single output after a trigger for digitalisation (external to the chip). Since the approaches are complementary the idea is to put both of them in the final front end chip. An overview of the system is given together to the actual status of the design. Results from simulations are shown: the system is feasible and we think to implement some devices this year to extensively test the proposed solutions

  12. Status report on front end electronics for the EUSO photon detector

    Energy Technology Data Exchange (ETDEWEB)

    Bosson, G.; Dzahini, D.; Koang, D.H.; Musico, P.; Pallavicini, M.; Pouxe, J.; Pratolongo, F.; Richer, J.P

    2002-12-01

    In this paper we'll give a status report on the design of the front end electronic system which will be used for the EUSO photon detector. For space, mass and power consumption constraints the system will be implemented developing an ASIC chip using a deep submicron technology. Two complementary approaches will be described: a digital one (DFEE) and an analog one (AFEE). The DFEE is able to count the single photoelectrons coming form the detector, store the numbers in a memory buffer and read them out after a trigger using a serial communication line. The AFEE integrate the anode signals, store them in an analog memory and serially send all the values to a single output after a trigger for digitalisation (external to the chip). Since the approaches are complementary the idea is to put both of them in the final front end chip. An overview of the system is given together to the actual status of the design. Results from simulations are shown: the system is feasible and we think to implement some devices this year to extensively test the proposed solutions.

  13. Effect of Polymorphism of some Candidate Genes from Growth Hormone Axis on Egg Production Traits in Mazandaran Native Fowls

    Directory of Open Access Journals (Sweden)

    B Enayati

    2012-02-01

    Full Text Available In the present study the allelic polymorphisms of GH, GHR and TGFβ3 genes and its association with egg production traits were investigated. Blood samples randomly were collected from breeder hens of Mazandaran native fowls breeding station and transported to the laboratory in cold chain condition. DNA was extracted using modified salting out method and the desired loci were amplified by specific primers. All samples genotyping were carried out by RFLP-PCR method. The frequency of each (+ and (- alleles was estimated at 0.7981 and 0.2019 for GH, 0.9937 and 0.0063 for GHR and 0.8037 and 0.1961 for TGFβ3 loci, respectively. The heterozygote genotype was detected in both GH and TGFβ3 loci but all individuals showed homozygote genotype in GHR marker site. The chi-squared test showed that all individuals in both GH and TGFβ3 loci were in HW equilibrium. Statistical analysis of showed that GH marker site had a significant effect on both phenotypic and breeding values of egg weight at puberty (EWM and age at first laying egg (AFE, respectively. The mean comparison showed that individuals with -/- genotype in GH marker site had higher phenotypic values for EWM but lower breeding values for AFE trait. The GHR and TGFβ3 loci and also the interaction between GH×TGFβ3 loci were not statistically significant on phenotypic and breeding values of mentioned traits..

  14. Vibrational dynamics of amorphous metals by inelastic neutron and raman scattering

    International Nuclear Information System (INIS)

    Lustig, N.E.

    1986-01-01

    Time-of-flight inelastic neutron scattering and Raman measurements were performed on amorphous (a-) metals. The neutron-weighted vibrational density of states, G(E), obtained for a-Fe 78 P 22 , a-Ni 82 B 18 and a-Ni 67 B 33 transition metal metalloid alloys (TM-m), indicated two major vibrational bands: a low frequency acoustic-like band and a high frequency optic-like band, derived from TM-TM and TM-m interactions, respectively. Similar neutron measurements were performed on the corresponding polycrystalline (c-) alloys, c-Fe 3 P and c-Ni 2 B. A comparison of the amorphous and crystalline densities of states indicates the elimination of sharp features and the addition of vibrational states at low and high frequencies upon amorphization. The experimental G(E) results for a-Fe 78 P 22 are in good agreement with the theoretically predicted spectrum. A comparison between the a-Ni 67 B 33 and the phenomenologically broadened c-Ni 2 B spectrum indicates a change in the short-range order. This finding is consistent with structural measurements on this alloy. Raman measurements were carried out using interference enhanced Raman spectroscopy (IERS) on thin film Ni-B alloys. The measured spectra provide information about the weighted phonon density of states, and is in good agreement with the neutron results

  15. Significance of likes: Analysing passive interactions on Facebook during campaigning.

    Directory of Open Access Journals (Sweden)

    Mohammad Adib Khairuddin

    Full Text Available With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS to measure the passive interactions between a candidate's posts on Facebook and the users (liking the posts. Using this method on original Malaysian General Election (MGE13 and Australian Federal Elections (AFE13 Facebook Pages (FP campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning.

  16. Significance of likes: Analysing passive interactions on Facebook during campaigning.

    Science.gov (United States)

    Khairuddin, Mohammad Adib; Rao, Asha

    2017-01-01

    With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions) in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS) to measure the passive interactions between a candidate's posts on Facebook and the users (liking the posts). Using this method on original Malaysian General Election (MGE13) and Australian Federal Elections (AFE13) Facebook Pages (FP) campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning.

  17. Participation in Pre-High School Football and Neurological, Neuroradiological, and Neuropsychological Findings in Later Life: A Study of 45 Retired National Football League Players.

    Science.gov (United States)

    Solomon, Gary S; Kuhn, Andrew W; Zuckerman, Scott L; Casson, Ira R; Viano, David C; Lovell, Mark R; Sills, Allen K

    2016-05-01

    A recent study found that an earlier age of first exposure (AFE) to tackle football was associated with long-term neurocognitive impairment in retired National Football League (NFL) players. To assess the association between years of exposure to pre-high school football (PreYOE) and neuroradiological, neurological, and neuropsychological outcome measures in a different sample of retired NFL players. Cross-sectional study; Level of evidence, 3. Forty-five former NFL players were included in this study. All participants prospectively completed extensive history taking, a neurological examination, brain magnetic resonance imaging, and a comprehensive battery of neuropsychological tests. To measure the associations between PreYOE and these outcome measures, multiple regression models were utilized while controlling for several covariates. After applying a Bonferroni correction for multiple comparisons, none of the neurological, neuroradiological, or neuropsychological outcome measures yielded a significant relationship with PreYOE. A second Bonferroni-corrected analysis of a subset of these athletes with self-reported learning disability yielded no significant relationships on paper-and-pencil neurocognitive tests but did result in a significant association between learning disability and computerized indices of visual motor speed and reaction time. The current study failed to replicate the results of a prior study, which concluded that an earlier AFE to tackle football might result in long-term neurocognitive deficits. In 45 retired NFL athletes, there were no associations between PreYOE and neuroradiological, neurological, and neuropsychological outcome measures. © 2016 The Author(s).

  18. Produtividade e características biométricas do capim-braquiária em sistema silvipastoril

    Directory of Open Access Journals (Sweden)

    Cristiam Bosi

    2014-06-01

    Full Text Available O objetivo deste trabalho foi avaliar a produtividade e as características biométricas do capim-braquiária (Urochloa decumbens sob pastejo, em sistema silvipastoril. Avaliou-se um sistema com árvores nativas de interesse comercial, plantadas em renques, no sentido norte-sul, espaçados por 17 m. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições e parcelas subdivididas, tendo-se avaliado o ciclo de rebrota da forragem nas parcelas, e a distância desta em relação aos renques, nas subparcelas. Sete ciclos de rebrota foram avaliados, em quatro distâncias dos renques: a 2 e a 6 m do renque leste, e a 2 e a 6 m do renque oeste. Quantificou-se a produtividade de matéria seca, o índice de área foliar (IAF, a área foliar específica (AFE e a altura das plantas. A produtividade de forragem, nos dois primeiros ciclos, e o IAF, no segundo e no terceiro ciclo, diminuiram com níveis de sombra acima de 39 e 40%, respectivamente. Já a altura de plantas aumentou com sombreamentos superiores a 53%, nos quatro primeiros ciclos; o que também ocorreu com a AFE, com sombreamento superior a 66%, nos três primeiros ciclos.

  19. Propiedades psicométricas de la Escala de Satisfacción con la Vida en los Estudiantes (SLSS de Huebner en niños y niñas de 10 a 12 años de Chile

    Directory of Open Access Journals (Sweden)

    Jaime Alfaro

    Full Text Available Este trabajo analiza las propiedades psicométricas de la escala SLSS de Huebner en una muestra de niños y niñas chilenos. Se aplicó a 1096 estudiantes de 10 a 12 años (M=11; DT= 0.89 que asistían a establecimientos municipales, particulares subvencionados y particulares pagados en las ciudades de Santiago, Valparaíso y Concepción. Se realizaron análisis de fiabilidad de consistencia interna, análisis factorial exploratorio (AFE y confirmatorio (AFE. Los resultados exhiben una aceptable fiabilidad en tanto consistencia interna de la escala (α=.86, el análisis factorial arroja dos factores en la estructura factorial de la escala que se corresponden con satisfacción con la vida y deseo de cambio. Se discute la solución bifactorial del modelo seleccionado en tanto no se corresponde con lo comunmente reportado en otras investigaciones. El estudio reporta resultados del uso de SLSS en población infantil y aporta al uso y desarrollo de herramientas de medición de autorreporte para el estudio del bienestar subjetivo en niños chilenos.

  20. Neural network and wavelet average framing percentage energy for atrial fibrillation classification.

    Science.gov (United States)

    Daqrouq, K; Alkhateeb, A; Ajour, M N; Morfeq, A

    2014-03-01

    ECG signals are an important source of information in the diagnosis of atrial conduction pathology. Nevertheless, diagnosis by visual inspection is a difficult task. This work introduces a novel wavelet feature extraction method for atrial fibrillation derived from the average framing percentage energy (AFE) of terminal wavelet packet transform (WPT) sub signals. Probabilistic neural network (PNN) is used for classification. The presented method is shown to be a potentially effective discriminator in an automated diagnostic process. The ECG signals taken from the MIT-BIH database are used to classify different arrhythmias together with normal ECG. Several published methods were investigated for comparison. The best recognition rate selection was obtained for AFE. The classification performance achieved accuracy 97.92%. It was also suggested to analyze the presented system in an additive white Gaussian noise (AWGN) environment; 55.14% for 0dB and 92.53% for 5dB. It was concluded that the proposed approach of automating classification is worth pursuing with larger samples to validate and extend the present study. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  1. Validation of the coupling of mesh models to GEANT4 Monte Carlo code for simulation of internal sources of photons

    International Nuclear Information System (INIS)

    Caribe, Paulo Rauli Rafeson Vasconcelos; Cassola, Vagner Ferreira; Kramer, Richard; Khoury, Helen Jamil

    2013-01-01

    The use of three-dimensional models described by polygonal meshes in numerical dosimetry enables more accurate modeling of complex objects than the use of simple solid. The objectives of this work were validate the coupling of mesh models to the Monte Carlo code GEANT4 and evaluate the influence of the number of vertices in the simulations to obtain absorbed fractions of energy (AFEs). Validation of the coupling was performed to internal sources of photons with energies between 10 keV and 1 MeV for spherical geometries described by the GEANT4 and three-dimensional models with different number of vertices and triangular or quadrilateral faces modeled using Blender program. As a result it was found that there were no significant differences between AFEs for objects described by mesh models and objects described using solid volumes of GEANT4. Since that maintained the shape and the volume the decrease in the number of vertices to describe an object does not influence so meant dosimetric data, but significantly decreases the time required to achieve the dosimetric calculations, especially for energies less than 100 keV

  2. A low power low noise analog front end for portable healthcare system

    Science.gov (United States)

    Yanchao, Wang; Keren, Ke; Wenhui, Qin; Yajie, Qin; Ting, Yi; Zhiliang, Hong

    2015-10-01

    The presented analog front end (AFE) used to process human bio-signals consists of chopping instrument amplifier (IA), chopping spikes filter and programmable gain and bandwidth amplifier. The capacitor-coupling input of AFE can reject the DC electrode offset. The power consumption of current-feedback based IA is reduced by adopting capacitor divider in the input and feedback network. Besides, IA's input thermal noise is decreased by utilizing complementary CMOS input pairs which can offer higher transconductance. Fabricated in Global Foundry 0.35 μm CMOS technology, the chip consumes 3.96 μA from 3.3 V supply. The measured input noise is 0.85 μVrms (0.5-100 Hz) and the achieved noise efficient factor is 6.48. Project supported by the Science and Technology Commission of Shanghai Municipality (No. 13511501100), the State Key Laboratory Project of China (No. 11MS002), and the State Key Laboratory of ASIC & System, Fudan University.

  3. Synthesis and properties of Fe/Ni nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kozlovskiy, A. L., E-mail: artem88sddt@mail.ru; Zdorovets, M. V. [Institute of Nuclear Physics (Kazakhstan); Kadyrzhanov, K. K. [Eurasian National University (Kazakhstan)

    2016-09-15

    Fe/Ni nanotubes were formed in pores of polyethylenterephtalate-based template matrices by electrochemical deposition. The inner diameter, wall height, and thickness of the nanostructures, as well as the elemental and phase compositions, can be controlled by varying the deposition conditions. The volume deposition rate constants have been determined for each potential difference, due to which the nanostructure growth could be controlled. An X-ray diffraction analysis of the samples obtained at a potential difference of 1-1.6 V has revealed their composition to correspond to the substitutional solid solution, with an iron atom replaced by a nickel atom and dominance of the bcc a-Fe phase. The samples obtained at a potential difference of 1.8–2 V contain the bcc a-Fe phase and fcc Ni phase; the fcc phase dominates in the sample obtained at a potential difference of 2 V, which can be related to the high Ni content in nanotubes.

  4. Humus soil as a critical driver of flora conversion on karst rock outcrops.

    Science.gov (United States)

    Zhu, Xiai; Shen, Youxin; He, Beibei; Zhao, Zhimeng

    2017-10-03

    Rock outcrop is an important habitat supporting plant communities in karst landscape. However, information on the restoration of higher biotic populations on outcrops is limited. Here, we investigated the diversity, biomass changes of higher vascular plants (VP) and humus soil (HS) on karst outcrops during a restoration process. We surveyed VP on rock outcrops and measured HS reserved by various rock microhabitats in a rock desertification ecosystem (RDE), an anthropogenic forest ecosystem (AFE), and a secondary forest ecosystem (SFE) in Shilin County, southwest China. HS metrics (e.g. quantity and nutrients content) and VP metrics (e.g. richness, diversity and biomass) were higher at AFE than at RDE, but lower than at SFE, suggesting that the restoration of soil subsystem vegetation increased HS properties and favored the succession of VP on rock outcrops. There was significantly positive correlation between VP metrics and HS amount, indicating that the succession of VP was strongly affected by availability and heterogeneity of HS in various rock microhabitats. Thus, floral succession of rock subsystem was slow owing to the limited resources on outcrops, although the vegetation was restored in soil subsystem.

  5. Descripción de una nueva especie del género Sogda Lopatin, 1961 para la Península Ibérica (Coleoptera, Leiodidae, Leiodinae

    Directory of Open Access Journals (Sweden)

    Blanco Villero, José M.

    2014-12-01

    Full Text Available A new species of Sogda Lopatin, 1961 from the iberian Peninsula is described and illustrated. Specimens of the type series are from Saladar de Cordovilla (Albacete and Quero (Toledo. Sogda (Trichohydnobius ibericus n. sp. shares the set of characters that typify genus Sogda and it is possible to separate this species clearly from the other five known, based on morphological characters listed in the discussion. The Holotype and Paratypes have been deposited in the Museo Nacional de Ciencias Naturales, Madrid. urn:lsid:zoobank.org:pub:5BBBE2CF-EA8B-4B0E-893B-2A3AFE865875Se describe e ilustra una nueva especie del género Sogda Lopatin, 1961 de la península ibérica. Los especímenes de la serie tipo proceden del Saladar de Cordovilla (Albacete y de Quero (Toledo. Sogda (Trichohydnobius ibericus n. sp participa de todas las características que caracterizan al género Sogda, pudiendo separarse con claridad de las cinco especies conocidas tomando como base los caracteres morfológicos que se detallan en la discusión. Tanto el Holotipo como los Paratipos han sido depositados en el Museo Nacional de Ciencias Naturales de Madrid. urn:lsid:zoobank.org:pub:5BBBE2CF-EA8B-4B0E-893B-2A3AFE865875

  6. On the relationship between field cycling and imprint in ferroelectric Hf0.5Zr0.5O2

    Science.gov (United States)

    Fengler, F. P. G.; Hoffmann, M.; Slesazeck, S.; Mikolajick, T.; Schroeder, U.

    2018-05-01

    Manifold research has been done to understand the detailed mechanisms behind the performance instabilities of ferroelectric capacitors based on hafnia. The wake-up together with the imprint might be the most controversially discussed phenomena so far. Among crystallographic phase change contributions and oxygen vacancy diffusion, electron trapping as the origin has been discussed recently. In this publication, we provide evidence that the imprint is indeed caused by electron trapping into deep states at oxygen vacancies. This impedes the ferroelectric switching and causes a shift of the hysteresis. Moreover, we show that the wake-up mechanism can be caused by a local imprint of the domains in the pristine state by the very same root cause. The various domain orientations together with an electron trapping can cause a constriction of the hysteresis and an internal bias field in the pristine state. Additionally, we show that this local imprint can even cause almost anti-ferroelectric like behavior in ferroelectric films.

  7. Variation of the energy gap of the SbSI crystals at ferroelectric phase transition

    International Nuclear Information System (INIS)

    Audzijonis, A.; Zaltauskas, R.; Zigas, L.; Vinokurova, I.V.; Farberovich, O.V.; Pauliukas, A.; Kvedaravicius, A.

    2006-01-01

    Variation of the forbidden gap of SbSI crystals in the phase transition region is analyzed on the pseudopotential method for antiferroelectric and ferroelectric phase. The band gap at several special points of the Brillouin zone and some characteristic parameters of the band are considered. During the phase transition, the most significant changes are observed with the valence band top at points Q, C, R, H, E and with the conduction band bottom at points H, T and E of the Brillouin zone. At the ferroelectric phase transition, the valence and conduction bands change due to displacement of Sb and S atoms with respect to I and with respect to each other as a result of order-disorder and displacement-type transition. The obtained band gap values agree quite well with the experiment. This is apparently due to application of neutral rather than ionic atomic functions and inclusion of sufficiently many plane waves in the basis set for calculation

  8. Designing pseudocubic perovskites with enhanced nanoscale polarization

    Energy Technology Data Exchange (ETDEWEB)

    Levin, I. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA; Laws, W. J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA; Wang, D. [Department of Materials Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom; Reaney, I. M. [Department of Materials Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom

    2017-11-20

    A crystal-chemical framework has been proposed for the design of pseudocubic perovskites with nanoscale ferroelectric order, and its applicability has been demonstrated using a series of representative solid solutions that combined ferroelectric (K0.5Bi0.5TiO3, BaTiO3, and PbTiO3) and antiferroelectric (Nd-substituted BiFeO3) end members. The pseudocubic structures obtained in these systems exhibited distortions that were coherent on a scale ranging from sub-nanometer to tens of nanometers, but, in all cases, the macroscopic distortion remained unresolvable even if using high-resolution X-ray powder diffraction. Different coherence lengths for the local atomic displacements account for the distinctly different dielectric, ferroelectric, and electromechanical properties exhibited by the samples. The guidelines identified provide a rationale for chemically tuning the coherence length to obtain the desired functional response.

  9. Computational aspects of the smectization process in liquid crystals: An example study of a perfectly aligned two-dimensional hard-boomerang system.

    Science.gov (United States)

    Chrzanowska, Agnieszka

    2017-06-01

    A replica method for calculation of smectic liquid crystal properties within the Onsager theory has been presented and applied to an exemplary case of two-dimensional perfectly aligned needlelike boomerangs. The method allows one to consider the complete influence of the interaction terms in contrast to the Fourier expansion method which uses mostly first or second order terms of expansion. The program based on the replica algorithm is able to calculate a single representative layer as an equivalent set of layers, depending on the size of the considered width of the sample integration interval. It predicts successfully smectic density distributions, energies, and layer thicknesses for different types of layer arrangement-of the antiferroelectric or of the smectic A order type. Specific features of the algorithm performance and influence of the numerical accuracy on the physical properties are presented. Future applications of the replica method to freely rotating molecules are discussed.

  10. Proton glass behaviour in a solid solution of gamma-irradiated deuterated betaine phosphate sub 0 sub . sub 1 sub 5 betaine phosphite sub 0 sub . sub 8 sub 5

    CERN Document Server

    Banys, J; Klimm, C; Voelkel, G; Kloepperpieper, A

    1997-01-01

    Measurements of the dielectric permittivity are reported for a deuterated solid solution of gamma-irradiated antiferroelectric (betainephosphate) sub 0 sub . sub 1 sub 5 ferroelectric (betainephosphite) sub 0 sub . sub 8 sub 5 at frequencies 20 H sub Z

  11. Computational aspects of the smectization process in liquid crystals: An example study of a perfectly aligned two-dimensional hard-boomerang system

    Science.gov (United States)

    Chrzanowska, Agnieszka

    2017-06-01

    A replica method for calculation of smectic liquid crystal properties within the Onsager theory has been presented and applied to an exemplary case of two-dimensional perfectly aligned needlelike boomerangs. The method allows one to consider the complete influence of the interaction terms in contrast to the Fourier expansion method which uses mostly first or second order terms of expansion. The program based on the replica algorithm is able to calculate a single representative layer as an equivalent set of layers, depending on the size of the considered width of the sample integration interval. It predicts successfully smectic density distributions, energies, and layer thicknesses for different types of layer arrangement—of the antiferroelectric or of the smectic A order type. Specific features of the algorithm performance and influence of the numerical accuracy on the physical properties are presented. Future applications of the replica method to freely rotating molecules are discussed.

  12. Electronic transport in organometallic perovskite CH{sub 3}NH{sub 3}PbI{sub 3}: The role of organic cation orientations

    Energy Technology Data Exchange (ETDEWEB)

    Berdiyorov, G. R., E-mail: gberdiyorov@qf.org.qa; El-Mellouhi, F.; Madjet, M. E.; Rashkeev, S. N. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha (Qatar); Alharbi, F. H. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha (Qatar); College of Science and Engineering, Hamad Bin Khalifa University, Doha (Qatar)

    2016-02-01

    Density functional theory in combination with the nonequilibrium Green's function formalism is used to study the electronic transport properties of methylammonium lead-iodide perovskite CH{sub 3}NH{sub 3}PbI{sub 3}. Electronic transport in homogeneous ferroelectric and antiferroelectric phases, both of which do not contain any charged domain walls, is quite similar. The presence of charged domain wall drastically (by about an order of magnitude) enhances the electronic transport in the lateral direction. The increase of the transmission originates from the smaller variation of the electrostatic potential profile along the charged domain walls. This fact may provide a tool for tuning transport properties of such hybrid materials by manipulating molecular cations having dipole moment.

  13. Electrostatic micromotor based on ferroelectric ceramics

    Science.gov (United States)

    Baginsky, I. L.; Kostsov, E. G.

    2004-11-01

    A new electrostatic micromotor is described that utilizes the electromechanical energy conversion principle earlier described by the authors. The electromechanical energy conversion is based on reversible electrostatic rolling of thin metallic films (petals) on a ferroelectric surface. The motor's active media are layers of ferroelectric ceramics (about 100 µm in thickness). The characteristics of the electrostatic rolling of the petals on different ceramic surfaces are studied, as well as the dynamic characteristics of the micromotors. It is shown that the use of antiferroelectric material allows one to reach a specific energy capacitance comparable to that of the micromotors based on ferroelectric films and to achieve a specific power of 30-300 µW mm-2.

  14. Calamitic Smectic A-Polar Smectic APA Transition Observed in Bent Molecules with Large Bent-Angle Central Core of 4,6-Dichlorobenzene and Alkylthio Terminal Tail

    Science.gov (United States)

    Nguyen, Ha; Kang, Sungmin; Tokita, Masatoshi; Watanabe, Junji

    2011-07-01

    New homologs of bent molecules with a large bent-angle central core of 4,6-dichloro benzene and an alkylthio terminal tail have been synthesized. Although the corresponding alkoxy-tail homologs show only the calamitic phases because of its large bent angles around 160°, the new homologs with an alkylthio tail exhibit the antiferroelectric smectic APA (SmAPA) banana phase that is transformed on cooling from the calamitic smectic A (SmA) phase. The biaxial polar packing of bent molecules in the SmAPA phase is considered to arise from the hindered rotation around the molecular long axis due to the expansion of the mesophase temperatures to a lower temperature region. This study indicates that the bent molecules, even with a large bent angle, have the potential to form a switchable banana phase with a remarkable decrease in its phase temperature range to around 60 °C.

  15. Mass-selective Neutron Spectroscopy Beyond the Proton

    International Nuclear Information System (INIS)

    Krzystyniak, M; Seel, A G; Richards, S E; Gutmann, M J; Fernandez-Alonso, F

    2014-01-01

    We discuss ongoing methodological developments underpinning the determination of nuclear-momentum distributions from mass-resolved neutron Compton data of lightweight materials. To this end, two systems are considered in detail, namely, lithium hydride (including its deuterated counterpart) and squaric acid, an organic antiferroelectric material containing hydrogen, carbon, and oxygen. Beyond the usual case of the proton, our approach enables direct access to detailed line shape information associated with the underlying nuclear-momentum distributions of both deuterium and lithium. For oxygen and carbon, mean kinetic energies can also be obtained directly from the neutron data, as demonstrated by a detailed analysis of mass- resolved data from squaric acid. From an instrumentation point of view, this work provides a suitable platform for a detailed assessment of existing capabilities and future developments in mass-selective neutron spectroscopy on the VESUVIO spectrometer at ISIS

  16. Prediction of compounds with electric and magnetic ordering

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, L G [Rybinskij Aviatsionnyj Tekhnologicheskij Inst. (USSR)

    1979-03-01

    The possibility of polymorphic transformations from the structure of the pyrochlore type into that of the perovskite type for nine lead-containing compounds has been forecast. Some of them (PbTaO/sub 3/, Pb/sub 2/NiTaO/sub 6/, Pb/sub 2/MnTaO/sub 6/, Pb/sub 2/SmTaO/sub 6/) are expected to have, in addition to common for all lead-containing perovskites ferro-or antiferro-electric properties, specific magnetic properties. The periods of elementary cells of new perovskites are forecast. The possibility of considerable reduction of the number of errors when searching thermodynamical parameters of transformation has been shown.

  17. The effect of lactate unit number in compounds with azo group in the molecular core

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Hamplová, Věra; Kašpar, Miroslav; Podoliak, Natalia; Bubnov, Alexej; Glogarová, Milada; Nonnenmacher, D.; Giesselmann, F.

    2011-01-01

    Roč. 38, č. 5 (2011), s. 649-655 ISSN 0267-8292 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA ČR(CZ) GAP204/11/0723 Grant - others:RFASI(RU) 02.740.11.5166; Společný projekt AV ČR-DAAD SNR(CZ) D4-CZ5/2010-2011; GA UK(CZ) SVV-2011-263303 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * ferroelectricity * chirality * azo group * antiferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.858, year: 2011 http://dx.doi.org/10.1080/02678292.2011.565426

  18. Structure ordering effect on dielectric properties of PbIn/sub 0. 5/Nb/sub 0. 5/O/sub 3/ crystals

    Energy Technology Data Exchange (ETDEWEB)

    Turik, A V; Kupriyanov, M F; Zhestkov, B F

    1985-09-01

    Results are presented of dielectric and X-ray diffraction investigations into the PbIn/sub 0.5/Nb/sub 0.5/O/sub 3/ monocrystals of PbB/sub 0.5/'B/sub 0.5/''O/sub 3/ series (B'=ScIn, B''=Nb, Ta) annealed during 5 hours at 500 deg C. It is shown that ordering in the B'-cation position in crystals influences the character of alternation of phases and physical properties. The PbIn/sub 0.5/Nb/sub 0.5/O/sub 3/ crystals may be either in rhombohedral ferro- or zhombic antiferroelectric phases depending on thermal prehistory.

  19. Transmission electron microscope studies of phase transitions in single crystals and ceramics of ferroelectric Pb(Sc1/2Ta1/2)O3

    International Nuclear Information System (INIS)

    Baba-Kishi, K.Z.; Barber, D.J.

    1990-01-01

    An account is given of transmission electron microscope investigations of the phase transitions in single crystals and ceramics of the complex perovskite-structured ferroelectric 'relaxor' compound Pb(Sc 1/2 Ta 1/2 )O 3 . The crystal symmetries pertaining to both the non-polar paraelectric (PE) and polar ferroelectric (FE) states have been studied by the technique of convergent-beam electron diffraction. A new phase transition has been discovered in the temperature range for which the FE and PE states coexist. The new phase transition is interpreted as the creation of a modulated antiferroelectric state, and this is viewed as marking a departure from relaxor behaviour towards more 'normal' ferroelectric behaviour. (orig.)

  20. An Automated Ab Initio Framework for Identifying New Ferroelectrics

    Science.gov (United States)

    Smidt, Tess; Reyes-Lillo, Sebastian E.; Jain, Anubhav; Neaton, Jeffrey B.

    Ferroelectric materials have a wide-range of technological applications including non-volatile RAM and optoelectronics. In this work, we present an automated first-principles search for ferroelectrics. We integrate density functional theory, crystal structure databases, symmetry tools, workflow software, and a custom analysis toolkit to build a library of known and proposed ferroelectrics. We screen thousands of candidates using symmetry relations between nonpolar and polar structure pairs. We use two search strategies 1) polar-nonpolar pairs with the same composition and 2) polar-nonpolar structure type pairs. Results are automatically parsed, stored in a database, and accessible via a web interface showing distortion animations and plots of polarization and total energy as a function of distortion. We benchmark our results against experimental data, present new ferroelectric candidates found through our search, and discuss future work on expanding this search methodology to other material classes such as anti-ferroelectrics and multiferroics.

  1. Magnetoelectric effect in lead free piezoelectric Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}–modified CFO based magnetostrictive (Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7} Mn{sub 0.3}O{sub 4}) particulate nanocomposite prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Megha [Nanotechnology Research Laboratory, Desh Bhagat University, Mandi Govindgarh 147330, Punjab (India); Sharma, Puneet [School of Physics & Materials Science, Thapar University, Patiala 147004, Punjab (India); Kumari, Mukesh; Singh, Anoop Pratap [Magnetics & Advanced ceramics laboratory, Department of Physics, Indian Institute of Technology, Delhi 110016 (India); Tyagi, Mintu, E-mail: mintutyagi@deshbhagatuniversity.in [Nanotechnology Research Laboratory, Desh Bhagat University, Mandi Govindgarh 147330, Punjab (India)

    2017-03-15

    Lead free magnetoelectric composites that comprise Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4} (CZFMO) and Bi{sub 1/2}Na{sub 1/2}TiO{sub 3} (BNT) were synthesized using sol-gel method and it's structural, dielectric, magnetic, ferroelectric and magnetoelectric (ME) properties were studied. The X-ray diffraction displayed the single phase formation of parent phases and the presence of two phases in the composites. The temperature dependent dielectric spectra of samples indicates two anomalies at ~220 °C and ~320 °C were ascribed to ferroelectric to antiferroelectric, and anti-ferroelectric to paraelectric phase transitions respectively. Room temperature (RT) magnetic measurements show that composites are soft magnetic. The composite with x=0.2, showed the large value of ME voltage coefficient (α{sub E})~58 mV/cmOe. Moreover, these ME composites provide a great opportunity as potential lead free systems for multifunctional devices. - Highlights: • In this work, Modified CFO based lead free particulate nanocomposites with significantly high value of ME coupling coefficient α{sub E} ~52 mV/cmOe have been prepared. • This sufficient high value of α{sub E} in such composites is obtained by manipulating/improving the piezomagnetic component. • The studies on BNT based particulate ME composites are very scarce in literature. However, no report is available in on the modified CFO based lead free particulate composites.

  2. The depolarization performances of 0.97PbZrO3-0.03Ba(Mg1/3Nb2/3)O3 ceramics under hydrostatic pressure

    Science.gov (United States)

    Su, Rigu; Nie, Hengchang; Liu, Zhen; Peng, Ping; Cao, Fei; Dong, Xianlin; Wang, Genshui

    2018-02-01

    Several 0.97PbZrO3-0.03Ba(Mg1/3Nb2/3)O3 (0.97PZ-0.03BMN) ceramics were prepared via the columbite precursor method. Their microstructures and pressure-dependent ferroelectric and depolarization performances were then studied. The X-ray diffraction patterns of ground and fresh samples indicate that a main rhombohedral symmetry crystal structure is present in the bulk and that it sits alongside a trace quantity of an orthorhombic antiferroelectric phase that results from the effect of grinding on the surface. The remanent polarization (Pr) of the 0.97PZ-0.03BMN reached 32.4 μC/cm2 at 4.5 kV/mm and ambient pressure. In an in situ pressure-induced current measurement, more than 91% of the retained Pr of the pre-poled sample was released when the pressure was increased from 194 MPa to 238 MPa. That this pressure-driven depolarization should be attributed to the pressure-induced ferroelectric-antiferroelectric phase transition is supported by the emergence of double P-E loops at high hydrostatic pressures. Moreover, the 0.97PZ-0.03BMN ceramics exhibit no temperature-induced phase transitions and little related polarization loss up to 125 °C, which suggests that Pr has excellent thermal stability. The sharp depolarization behavior at low pressures and excellent temperature stability reveal that our 0.97PZ-0.03BMN ceramics exhibit superior performances in mechanical-electrical energy conversion applications.

  3. Structural, thermal, dielectric and phonon properties of perovskite-like imidazolium magnesium formate.

    Science.gov (United States)

    Mączka, Mirosław; Marinho Costa, Nathalia Leal; Gągor, Anna; Paraguassu, Waldeci; Sieradzki, Adam; Hanuza, Jerzy

    2016-05-18

    We report the synthesis and characterisation of a magnesium formate framework templated by protonated imidazole. Single-crystal X-ray diffraction data showed that this compound crystallizes in the monoclinic structure in the P21/n space group with lattice parameters a = 12.1246(4) Å, b = 12.2087(5) Å, c = 12.4991(4) Å and β = 91.39(1)°. The antiparallel arrangement of the dipole moments associated with imidazolium cations suggests the antiferroelectric character of the room-temperature phase. The studied compound undergoes a structural phase transition at 451 K associated with a halving of the c lattice parameter and the disappearance of the antiferroelectric order. The monoclinic symmetry is preserved and the new metrics are a = 12.261(7) Å, b = 12.290(4) Å, c = 6.280(4) Å, and β = 90.62(5)°. Raman and IR data are consistent with the X-ray diffraction data. They also indicate that the disorder of imidazolium cations plays a significant role in the mechanism of the phase transition. Dielectric data show that the phase transition is associated with a relaxor nature of electric ordering. We also report high-pressure Raman scattering studies of this compound that revealed the presence of two pressure-induced phase transitions near 3 and 7 GPa. The first transition is most likely associated with a rearrangement of the imidazolium cations without any significant distortion of these cations and the magnesium formate framework, whereas the second transition leads to strong distortion of both the framework and imidazolium cations. High-pressure data also show that imidazolium magnesium formate does not show any signs of amorphization up to 11.4 GPa.

  4. Effective ionization coefficient of C5 perfluorinated ketone and its mixtures with air

    Science.gov (United States)

    Aints, Märt; Jõgi, Indrek; Laan, Matti; Paris, Peeter; Raud, Jüri

    2018-04-01

    C5 perfluorinated ketone (C5 PFK with UIPAC chemical name 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanone and sold by 3M as Novec™ 5110) has a high dielectric strength and a low global warming potential, which makes it interesting as an insulating gas in medium and high-voltage applications. The study was carried out to determine the effective Townsend ionization coefficient α eff as a function of electric field strength and gas density for C5 PFK and for its mixtures with air. The non-self-sustained Townsend discharge between parallel plate electrodes was initiated by illuminating the cathode by UV radiation. The discharge current, I, was measured as a function of inter-electrode distance, d, at different gas densities, N, and electric field strengths, E. The effective ionization coefficient α eff was determined from the semi-logarithmic plots of I/I 0 against d. For each tested gas mixture, the density normalized effective ionization coefficient α eff/N was found to be a unique function of reduced electric field strength E/N. The measurements were carried out in the absolute pressure range of 0.05-1.3 bar and E/N range of 150-1200 Td. The increasing fraction of C5 PFK in air resulted in the decrease of effective ionization coefficient. The limiting electric field strength (E/N)lim where the effective ionization coefficient α eff became zero was 770 Td (190 kV cm-1 at 1 bar) for pure C5 PFK and decreased to 225 Td (78 kV cm-1 at 1.4 bar) for 7.6% C5 PFK/air mixture. The latter value of (E/N)lim is still more than two times higher than the (E/N)lim value of synthetic air and about two-thirds of the value corresponding to pure SF6. The investigated gas mixtures have the potential to become an alternative to SF6 in numerous high- and medium-voltage applications.

  5. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-10-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. A pulsed corona discharge (PCD) reactor has been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. A nonthermal plasma cannot be produced in pure H{sub 2}S with our reactor geometry, even at discharge voltages of up to 30 kV, because of the high dielectric strength of pure H{sub 2}S ({approx}2.9 times higher than air). Therefore, H{sub 2}S was diluted in another gas with lower breakdown voltage (or dielectric strength). Breakdown voltages of H{sub 2}S in four balance gases (Ar, He, N{sub 2} and H{sub 2}) have been measured at different H{sub 2}S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H{sub 2}S and the balance gas. H{sub 2}S conversion and the reaction energy efficiency depend on the balance gas and H{sub 2}S inlet concentrations. With increasing H{sub 2}S concentrations, H{sub 2}S conversion initially increases, reaches a maximum, and then decreases. H{sub 2}S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gases, such as N{sub 2} and H{sub 2}. These observations can be explained by the proposed reaction mechanism of H{sub 2}S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H{sub 2}S into hydrogen and sulfur.

  6. Differences in the prevalence of hospitalizations and utilization of emergency outpatient services for ambulatory care sensitive conditions between asylum-seeking children and children of the general population: a cross-sectional medical records study (2015

    Directory of Open Access Journals (Sweden)

    Célina Lichtl

    2017-11-01

    Full Text Available Abstract Background Hospitalizations for ambulatory care sensitive (ACS conditions are established indicators for the availability and quality of ambulatory care. We aimed to assess the differences between asylum-seeking children and children of the general population in a German city with respect to (i the prevalence of ACS hospitalizations, and (ii the utilization of emergency outpatient services for ACS conditions. Methods Using anonymous account data, all children admitted to the University Hospital Heidelberg in 2015 were included in our study. A unique cost unit distinguished asylum seekers residing in a nearby reception center (exposed from the children of the general population. We adapted international lists of ACS conditions and calculated the prevalence of ACS hospitalizations and the utilization of emergency outpatient services for ACS conditions, attributable fractions among the exposed (Afe and the population attributable fraction among total admissions (PAF for each outcome. Differences in the prevalence of each outcome between exposed and controls were analyzed in logistic regression models adjusted for sex, age group and quarterly admission. Results Of the 32,015 admissions in 2015, 19.9% (6287 were from inpatient and 80.1% (25,638 from outpatient care. In inpatient care, 9.8% (622 of all admissions were hospitalizations for ACS conditions. The Afe of ACS hospitalizations was 46.57%, the PAF was 1.12%. Emergency service use for ACS conditions could be identified in 8.3% (3088 of all admissions (Afe: 79.57%, PAF: 5.08%. The odds ratio (OR of asylum-seeking children being hospitalized for ACS conditions in comparison to the control group was 1.81 [95% confidence interval, CI: 1.02; 3.2]. The OR of the asylumseeking population compared to the general population for the utilization of emergency service use for ACS conditions was 4.93 [95% CI: 4.11; 5.91]. Conclusions Asylum-seeking children had significantly higher odds of ACS

  7. An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

    Science.gov (United States)

    Edward, Alexander; Chan, Pak Kwong

    This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18µm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6V. The designed IA achieves 30dB of closed-loop gain, 101dB of common-mode rejection ratio (CMRR) at 50Hz, 80dB of power-supply rejection ratio (PSRR) at 50Hz, thermal noise floor of 53.4 nV/√Hz, current consumption of 14µA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6V supply from a 0.8-1.0V energy harvesting power source. It achieves power supply rejection (PSR) of 42dB at frequency of 1MHz. A cascode compensated pseudo differential amplifier is used as the filter's building block for low power design. The filter's single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6dB of signal-to-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100Hz sinusoidal maximum input signal, bandwidth of 2kHz, and power consumption of 51.2µW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18µm CMOS process.

  8. Overview of adaptive finite element analysis in computational geodynamics

    Science.gov (United States)

    May, D. A.; Schellart, W. P.; Moresi, L.

    2013-10-01

    The use of numerical models to develop insight and intuition into the dynamics of the Earth over geological time scales is a firmly established practice in the geodynamics community. As our depth of understanding grows, and hand-in-hand with improvements in analytical techniques and higher resolution remote sensing of the physical structure and state of the Earth, there is a continual need to develop more efficient, accurate and reliable numerical techniques. This is necessary to ensure that we can meet the challenge of generating robust conclusions, interpretations and predictions from improved observations. In adaptive numerical methods, the desire is generally to maximise the quality of the numerical solution for a given amount of computational effort. Neither of these terms has a unique, universal definition, but typically there is a trade off between the number of unknowns we can calculate to obtain a more accurate representation of the Earth, and the resources (time and computational memory) required to compute them. In the engineering community, this topic has been extensively examined using the adaptive finite element (AFE) method. Recently, the applicability of this technique to geodynamic processes has started to be explored. In this review we report on the current status and usage of spatially adaptive finite element analysis in the field of geodynamics. The objective of this review is to provide a brief introduction to the area of spatially adaptive finite analysis, including a summary of different techniques to define spatial adaptation and of different approaches to guide the adaptive process in order to control the discretisation error inherent within the numerical solution. An overview of the current state of the art in adaptive modelling in geodynamics is provided, together with a discussion pertaining to the issues related to using adaptive analysis techniques and perspectives for future research in this area. Additionally, we also provide a

  9. Genome-wide association study on reproductive traits in Jinghai Yellow Chicken.

    Science.gov (United States)

    Zhang, G X; Fan, Q C; Wang, J Y; Zhang, T; Xue, Q; Shi, H Q

    2015-12-01

    To identify molecular markers and candidate genes associated with reproductive traits, a genome-wide analysis was performed in Jinghai Yellow Chickens to analyze body weight at first oviposition (BWF), age at first oviposition (AFE), weight of the egg at first oviposition (FEW), egg weight at the age of 300 days (EW300), number of eggs produced by 300 days of age (EN300), egg hatchability (HA) and multiple selection index for egg production (MSI). The results showed that seven single nucleotide polymorphisms (SNPs) were associated with reproductive traits (Preproductive traits were identified (Preproductive traits will greatly advance the understanding of the genetic basis and molecular mechanisms underlying reproductive traits and may have practical significance in breeding programs for the improvements of reproductive traits in the Jinghai Yellow Chicken. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Primera revisión del Cuestionario de Calidad de Vida para Adultos Mayores en Comunidad ccvamc-62

    Directory of Open Access Journals (Sweden)

    José González Tovar

    2016-01-01

    Full Text Available Se tiene como objetivo confirmarla estructura del Cuestionario de Calidad deVida para Adultos Mayores en Comunidad enCoahuila, México. El muestreo fue intencional,535 adultos mayores, 49% hombres y51% mujeres. El instrumento contó con 104reactivos organizados en nueve dimensiones:bienestar físico, autodeterminación, vivienda,seguridad material, participación ciudadana,bienestar emocional, relaciones interpersonales,educación, bienestar espiritual y plan de vida.Se obtuvo la consistencia interna y el análisisfactorial exploratorio (afe y confirmatorio(afc. La estructura es similar a la propuestade Verdugo Alonso (2009 y también se puederelacionar con las categorías de Arita Watanabe(2005. Se logró una reducción de nueve a sietedimensiones y de 104 a 62 reactivos.

  11. OSTEOSYNTHESIS OF THE SPINE AT PATHOLOGICAL FRACTURES AGAINST THE BACKGROUND OF EXTENSIVE METASTATIC SPREAD IN COMBINATION WITH RADIO- AND CHEMOTHERAPY

    Directory of Open Access Journals (Sweden)

    R. M. Tikhilov

    2010-01-01

    Full Text Available The results of the stabilizing spine osteosynthesis in 82 patients with extensive metastatic spread are presented. Patients have been distributed to 3 groups: in I group the extended osteosynthesis of a spine without application cement vertebroplasty was carried out, in II group the extended spine osteosynthesis was performed, but with performance vertebroplasty through cannulated screws, in III group the limited osteosynthesis with cement vertebroplasty through cannulas screws was applied. Results of treatment were estimated considering spine support ability, elimination of a painful syndrome (scale of pain McAfee, 1989 and neurologic dysfunctions (scale ASIA/IMSOP, 1992, improvement of quality of a life (scale SF-36. The received positive results of treatment allow to conclude that tactics of treatment has been chosen correctly.

  12. Concurrent Driving Method with Fast Scan Rate for Large Mutual Capacitance Touch Screens

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Ahmed Mohamed

    2015-01-01

    Full Text Available A novel touch screen control technique is introduced, which scans each frame in two steps of concurrent multichannel driving and differential sensing. The proposed technique substantially increases the scan rate and reduces the ambient noise effectively. It is also extended to a multichip architecture to support excessively large touch screens with great scan rate improvement. The proposed method has been implemented using 0.18 μm CMOS TowerJazz process and tested with FPGA and AFE board connecting a 23-inch touch screen. Experimental results show a scan rate improvement of up to 23.8 times and an SNR improvement of 24.6 dB over the conventional method.

  13. The development of a Codependency Scale

    Directory of Open Access Journals (Sweden)

    Cremonte, Mariana

    2013-04-01

    Full Text Available Codependency is defined as a dysfunctional pattern of relating to others, present in relatives of those with a substance use disorder or other chronic disease. It is characterized by emotional dependence, extreme focus in the other person, and self-neglect. Aim: to present results of the process of development and validation of a new measure to evaluate codependency. Method: The Argentinean codependency scale was administered to a convenience sample of 347 subjects between 15 and 80 years, in Mar del Plata. AFE was used (main axes extraction method. The number of factors was determined by parallel analysis. Internal consistency was assessed using Cronbach's Alpha. Item level statistics were also estimated. Results: Three factors were obtained. The internal consistency of the total scale and the three subscales was satisfactory. Relatives of alcohol or drugs dependents and of people with other chronic diseases had scores significantly higher in the codependency measure than those in the general population group.

  14. Characterisation by esca of iron componds formed on the nuclear steels by surface engeneering

    International Nuclear Information System (INIS)

    Minca, M.; Oncioiu, G.; Coaca, E.; Rusu, O.; Florea, S.; Andrei, V.

    2013-01-01

    In this work it is presented an approach for characterization of the oxide films by assigning the binding energy of the chemical states according with a theoretical analysis. In order to exemplify the method developed there are presented analyses on the internal standards a-Fe 2 O 3 and Fe 3 O 4 ), as well as analysis of superficial structure on austenitic steel samples on which different treatments of surface engineering were made. It is also presented a depth profiling analysis type, achieved by ball cratering method, which allow determining the distribution of different chemical elements with depth. One can follow the distribution of the valence states, Fe 2+ and Fe 3+ , with depth. By means of the presented method it can be precisely determined the valence states of Fe and their weight in the oxide iron films. (authors)

  15. Quantum oscillations in antiferromagnetic CaFe2As2 on the brink of superconductivity

    International Nuclear Information System (INIS)

    Harrison, N; McDonald, R D; Mielke, C H; Bauer, E D; Ronning, F; Thompson, J D

    2009-01-01

    We report quantum oscillation measurements on CaFe 2 As 2 under strong magnetic fields-recently reported to become superconducting under pressures of as little as a kilobar. The largest observed carrier pocket occupies less than 0.05% of the paramagnetic Brillouin zone volume-consistent with Fermi surface reconstruction caused by antiferromagnetism. On comparing several alkaline earth AFe 2 As 2 antiferromagnets (with A = Ca, Sr and Ba), the dependences of the Fermi surface cross-sectional area F α and the effective mass m α * of the primary observed pocket on the antiferromagnetic/structural transition temperature T s are both found to be consistent with the case for quasiparticles in a conventional spin-density wave model. These findings suggest that the recently proposed strain-enhanced superconductivity in these materials occurs within a broadly conventional spin-density wave phase. (fast track communication)

  16. Navier-Stokes structure of merged layer flow on the spherical nose of a space vehicle

    Science.gov (United States)

    Jain, A. C.; Woods, G. H.

    1988-01-01

    Hypersonic merged layer flow on the forepart of a spherical surface of a space vehicle has been investigated on the basis of the full steady-state Navier-Stokes equations using slip and temperature jump boundary conditions at the surface and free-stream conditions far from the surface. The shockwave-like structure was determined as part of the computations. Using an equivalent body concept, computations were carried out under conditions that the Aeroassist Flight Experiment (AFE) Vehicle would encounter at 15 and 20 seconds in its flight path. Emphasis was placed on understanding the basic nature of the flow structure under low density conditions. Particular attention was paid to the understanding of the structure of the outer shockwave-like region as the fluid expands around the sphere. Plots were drawn for flow profiles and surface characteristics to understand the role of dissipation processes in the merged layer of the spherical nose of the vehicle.

  17. A high-frequency transimpedance amplifier for CMOS integrated 2D CMUT array towards 3D ultrasound imaging.

    Science.gov (United States)

    Huang, Xiwei; Cheong, Jia Hao; Cha, Hyouk-Kyu; Yu, Hongbin; Je, Minkyu; Yu, Hao

    2013-01-01

    One transimpedance amplifier based CMOS analog front-end (AFE) receiver is integrated with capacitive micromachined ultrasound transducers (CMUTs) towards high frequency 3D ultrasound imaging. Considering device specifications from CMUTs, the TIA is designed to amplify received signals from 17.5MHz to 52.5MHz with center frequency at 35MHz; and is fabricated in Global Foundry 0.18-µm 30-V high-voltage (HV) Bipolar/CMOS/DMOS (BCD) process. The measurement results show that the TIA with power-supply 6V can reach transimpedance gain of 61dBΩ and operating frequency from 17.5MHz to 100MHz. The measured input referred noise is 27.5pA/√Hz. Acoustic pulse-echo testing is conducted to demonstrate the receiving functionality of the designed 3D ultrasound imaging system.

  18. Preliminary X-ray crystallographic analysis of sulfide:quinone oxidoreductase from Acidithiobacillus ferrooxidans

    International Nuclear Information System (INIS)

    Zhang, Yanfei; Cherney, Maia M.; Solomonson, Matthew; Liu, Jianshe; James, Michael N. G.; Weiner, Joel H.

    2009-01-01

    The sulfide:quinone oxidoreductase from A. ferrooxidans ATCC 23270 was overexpressed in E. coli and purified. Crystallization and preliminarily X-ray crystallographic analysis were performed for the recombinant enzyme. The gene product of open reading frame AFE-1293 from Acidithiobacillus ferrooxidans ATCC 23270 is annotated as encoding a sulfide:quinone oxidoreductase, an enzyme that catalyses electron transfer from sulfide to quinone. Following overexpression in Escherichia coli, the enzyme was purified and crystallized using the hanging-drop vapour-diffusion method. The native crystals belonged to the tetragonal space group P4 2 2 1 2, with unit-cell parameters a = b = 131.7, c = 208.8 Å, and diffracted to 2.3 Å resolution. Preliminary crystallographic analysis indicated the presence of a dimer in the asymmetric unit, with an extreme value of the Matthews coefficient (V M ) of 4.53 Å 3 Da −1 and a solvent content of 72.9%

  19. Functional Analysis of Battery Management Systems using Multi-Cell HIL Simulator

    DEFF Research Database (Denmark)

    Barreras, Jorge Varela; Swierczynski, Maciej Jozef; Schaltz, Erik

    2015-01-01

    Developers and manufacturers of Battery Management Systems (BMSs) require extensive testing of controller HW and SW, such as analog front-end (AFE) and performance of generated control code. In comparison with tests conducted on real batteries, tests conducted on hardware-in-the-loop (HIL......) simulator may be more costant time effective, easier to reproduce and safer beyond the normal range of operation, especially at early stages in the development process or during fault simulation. In this paper a li-ion battery (LIB) electro-thermal multicell model coupled with an aging model is designed......, characterized and validated based on experimental data, converted to C code and emulated in real-time with a dSpace HIL simulator. The BMS to be tested interacts with the emulated battery pack as if it was managing a real battery pack. BMS functions such as protection, measuring of current, voltage...

  20. Performance Evaluation of Electronic Inductor-Based Adjustable Speed Drives with Respect to Line Current Interharmonics

    DEFF Research Database (Denmark)

    Soltani, Hamid; Davari, Pooya; Blaabjerg, Frede

    2017-01-01

    Electronic Inductor (EI)-based front-end rectifiers have a large potential to become the prominent next generation of Active Front End (AFE) topology used in many applications including Adjustable Speed Drives (ASDs) for systems having unidirectional power flow. The EI-based ASD is mostly...... attractive due to its improved harmonic performance compared to a conventional ASD. In this digest, the input currents of the EI-based ASD are investigated and compared with the conventional ASDs with respect to interharmonics, which is an emerging power quality topic. First, the main causes...... of the interharmonic distortions in the ASD applications are analyzed under balanced and unbalanced load conditions. Thereafter, the key role of the EI at the DC stage is investigated in terms of high impedance and current harmonics transfer. Obtained experiments and simulations for both EI-based and conventional ASD...

  1. Further Studies in Filmwise Condensation of Steam on Horizontal Finned Tubes

    Science.gov (United States)

    1992-03-01

    8217; OUITPUT 7(0C. ’AD AFE02 ALSZ ’,IS !IZ7 ,’hiTPiT ’ 7 097 AcCA . ~2 1 ENiTER 709;Etp !’S OU~TPUtT 70 ’AC S -2’ 1 NPUIT "CONlNE’C~T tifOl A.C L.PjC l...Ptczit1Pvap1 GAUGEc 2077 Ptezt2P-v~ p2 ITRANSDUCER 2080’ CORECION FOR AIR CONTAMNATION 20SI P~pPvp2*1 .E-3 ITRANSDUCER IN P 20Z P-~~1 -3 ISAT. PRESSU’RE IN P

  2. EXPLORATORY FACTOR ANALYSIS (EFA IN CONSUMER BEHAVIOR AND MARKETING RESEARCH

    Directory of Open Access Journals (Sweden)

    Marcos Pascual Soler

    2012-06-01

    Full Text Available Exploratory Factor Analysis (EFA is one of the most widely used statistical procedures in social research. The main objective of this work is to describe the most common practices used by researchers in the consumer behavior and marketing area. Through a literature review methodology the practices of AFE in five consumer behavior and marketing journals(2000-2010 were analyzed. Then, the choices made by the researchers concerning factor model, retention criteria, rotation, factors interpretation and other relevant issues to factor analysis were analized. The results suggest that researchers routinely conduct analyses using such questionable methods. Suggestions for improving the use of factor analysis and the reporting of results are presented and a checklist (Exploratory Factor Analysis Checklist, EFAC is provided to help editors, reviewers, and authors improve reporting exploratory factor analysis.

  3. Transforming business models through big data in the textile industry

    DEFF Research Database (Denmark)

    Aagaard, Annabeth

    , such as textile, and have led to disruption of established business models (Westerman et al., 2014; Weill and Woerner, 2015). Yet, little is known of the managerial process and facilitation of the digital transformation of business models through big data (McAfee and Brynjolfsson, 2012; Markus and Loebbecke, 2013).......The extensive stream of work on business models (BM) and business model innovation (BMI) has generated many important insights (Amit & Zott, 2001; Osterwalder, 2004; Markides, 2008, 2013; Chesbrough 2010; Teece, 2010; Zott et al, 2011). Yet, our understanding of business models remains fragmented...... as stressed by Zott et al. (2011), Weill et al. (2011) and David J. Teece (2010: 174), who states that: “the concept of a business model lacks theoretical grounding in economics or in business studies”. With the acceleration of digitization and use of big data analytics quality data are accessible...

  4. Data acquisition system of 16-channel EEG based on ATSAM3X8E ARM Cortex-M3 32-bit microcontroller and ADS1299

    Science.gov (United States)

    Toresano, L. O. H. Z.; Wijaya, S. K.; Prawito, Sudarmaji, A.; Badri, C.

    2017-07-01

    The prototype of the EEG (electroencephalogram) instrumentation systems has been developed based on 32-bit microcontrollers of Cortex-M3 ATSAM3X8E and Analog Front-End (AFE) ADS1299 (Texas Instruments, USA), and also consists of 16-channel dry-electrodes in the form of EEG head-caps. The ADS1299-AFE has been designed in a double-layer format PCB (Print Circuit Board) with daisy-chain configuration. The communication protocol of the prototype was based on SPI (Serial Peripheral Interface) and tested using USB SPI-Logic Analyzer Hantek4032L (Qingdao Hantek Electronic, China). The acquired data of the 16-channel from this prototype has been successfully transferred to a PC (Personal Computer) with accuracy greater than 91 %. The data acquisition system has been visualized with time-domain format in the multi-graph plotter, the frequency-domain based on FFT (Fast Fourier Transform) calculation, and also brain-mapping display of 16-channel. The GUI (Graphical User Interface) has been developed based on OpenBCI (Brain Computer Interface) using Java Processing and also can be stored of data in the *.txt format. Instrumentation systems have been tested in the frequency range of 1-50 Hz using MiniSim 330 EEG Simulator (NETECH, USA). The validation process has been done with different frequency of 0.1 Hz, 2 Hz, 5 Hz, and 50 Hz, and difference voltage amplitudes of 10 µV, 30 µV, 50 µV, 100 µV, 500 µV, 1 mV, 2 mV and 2.5 mV. However, the acquisition system was not optimal at a frequency of 0.1 Hz and for amplitude potentials of over 1 mV had differences of the order 10 µV.

  5. Validación cruzada del Perfil de Impacto de Salud Oral aplicado a enfermedad periodontal

    Directory of Open Access Journals (Sweden)

    José Moral de la Rubia

    2017-01-01

    Full Text Available El Perfil de Impacto de Salud Oral (OHIP - 14 es el instrumento más empleado para evaluar la eficacia de tratamientos odontológicos. Con el propósito de dilucidar su estructura factorial y establecer la validez cruzada de la escala aplica da a la enfermedad periodontal (OHIP - 14 - PD , este estudio tiene como objetivos : 1 explorar la estructura factorial del OHIP - 14 - PD , y 2 contrastar la invarianza de los modelos propuestos para e l OHIP - 14 y de los derivados del análisis factorial exploratorio (AFE entre una muestra de población general y una muestra clínica odontológica . Se aplicó el OHIP - 14 - PD a 249 pacientes adultos odontológicos y 256 adultos de población general de Monterrey, México . El AFE reveló modelos de uno, dos y tres factores. Los modelos jerarqui zados propuestos arrojaron soluciones inadmisibles. Se concluye que el modelo un if actor ial tuvo las mejores propiedades, aunque el bi factor ial (impacto físico [ítems del 1 al 7] y psicosocial [ítems del 8 al 14] también resultó válido. L os dos modelos fue ron invariante s e n pesos de medida, pero no en las varianzas de los factores y residuos. En ambos modelos, el ajuste mejor ó con la inclusión de la correlación entre los residuos de los ítems 5 y 6.

  6. Evaluation of the Psychometric Properties of NOC Outcomes "Anxiety Level" and "Anxiety Self-Control" in a Portuguese Outpatient Sample.

    Science.gov (United States)

    Sampaio, Francisco Miguel Correia; Araújo, Odete Sofia Silva Lomba; Sequeira, Carlos Alberto da Cruz; Lluch Canut, María Teresa; Martins, Teresa

    2017-01-25

    To adopt the language and to evaluate the psychometric properties of "Anxiety level" and "Anxiety self-control" NOC outcomes in Portuguese adult patients. Methodological design. The final European Portuguese version of the NOC outcome "Anxiety level," composed by 16 indicators, proved excellent internal consistency. Exploratory factor analysis (EFA) was forced to three factors. The NOC outcome "Anxiety self-control," composed of nine indicators, demonstrated a questionable internal consistency. EFA was forced to two factors. European Portuguese versions of the studied NOC outcomes proved to be tools with acceptable psychometric properties for evaluating anxiety in Portuguese patients. This study contributed to the development of NOC language and to the enrichment of nursing's body of knowledge. Adaptar a linguagem e avaliar as propriedades psicométricas dos resultados NOC "Nível de ansiedade" e "Autocontrolo da ansiedade" em utentes portugueses adultos. MÉTODOS: Estudo metodológico. A versão portuguesa do resultado NOC "Nível de ansiedade", composta por 16 indicadores, apresentou uma excelente consistência interna. A análise fatorial exploratória (AFE) foi forçada a três dimensões. O resultado NOC "Autocontrolo da ansiedade", composto por nove indicadores, apresentou uma consistência interna questionável. A AFE foi forçada a duas dimensões. CONCLUSÕES: As versões portuguesas dos resultados NOC estudados são instrumentos com propriedades psicométricas aceitáveis para avaliar a ansiedade em utentes portugueses. IMPLICAÇÕES PARA A PRÁTICA DE ENFERMAGEM: Este estudo contribuiu para o desenvolvimento da linguagem NOC e para enriquecer o corpo de conhecimento de Enfermagem. © 2017 NANDA International, Inc.

  7. Diseño y validación de una escala para medir la percepción sobre el trabajo en el primer nivel de atención en estudiantes de medicina de Latinoamérica

    Directory of Open Access Journals (Sweden)

    Percy Mayta-Tristán

    Full Text Available Objetivos. Diseñar y validar una escala para evaluar la percepción sobre el primer nivel de atención (PNA en estudiantes de medicina latinoamericanos. Materiales y métodos. Se realizó un estudio multicéntrico, observacional, en dos fases: i Se diseñó un cuestionario autoaplicado referente a la percepción sobre la labor del médico en el PNA, y ii Se aplicó el cuestionario en estudiantes de medicina de 18 universidades de ocho países hispanohablantes latinoamericanos. Se desarrolló un análisis factorial exploratorio (AFE por medio de un análisis de componentes principales con rotación ortogonal varimax. Se evaluó la adecuación y el ajuste de la muestra. La extracción de factores fue hecha en base a los criterios de Kaiser, la pendiente de Catell y la varianza explicada (>5%. La consistencia interna fue medida con el alfa de Cronbach. Resultados. Se incluyeron 423 estudiantes, el 53,4% pertenecían a universidades peruanas. Tras el AFE el cuestionario quedo constituido por 11 ítems, los cuales se distribuyen en tres dominios que, en su conjunto, explican el 55,47% de la varianza total. i Percepciones sobre el médico que trabaja en PNA, ii Percepciones sobre el trabajo asistencial en PNA y iii Percepciones sobre las consecuencias económicas de trabajar en PNA. Conclusiones. La escala presenta tres dominios y constituye un instrumento que puede ser usado para medir las percepciones sobre el trabajo médico en el primer nivel de atención en estudiantes de medicina latinoamericanos de habla hispana.

  8. Performance success or failure is influenced by weeks lost to injury and illness in elite Australian track and field athletes: A 5-year prospective study.

    Science.gov (United States)

    Raysmith, Benjamin P; Drew, Michael K

    2016-10-01

    To investigate the impact of training modification on achieving performance goals. Previous research demonstrates an inverse relationship between injury burden and success in team sports. It is unknown whether this relationship exists within individual sport such as athletics. A prospective, cohort study (n=33 International Track and Field Athletes; 76 athlete seasons) across five international competition seasons. Athlete training status was recorded weekly over a 5-year period. Over the 6-month preparation season, relationships between training weeks completed, the number of injury/illness events and the success or failure of a performance goal at major championships was investigated. Two-by-two table were constructed and attributable risks in the exposed (AFE) calculated. A mixed-model, logistic regression was used to determine the relationship between failure and burden per injury/illness. Receiver Operator Curve (ROC) analysis was performed to ascertain the optimal threshold of training week completion to maximise the chance of success. Likelihood of achieving a performance goal increased by 7-times in those that completed >80% of planned training weeks (AUC, 0.72; 95%CI 0.64-0.81). Training availability accounted for 86% of successful seasons (AFE=0.86, 95%CI, 0.46 to 0.96). The majority of new injuries occurred within the first month of the preparation season (30%) and most illnesses occurred within 2-months of the event (50%). For every modified training week the chance of success significantly reduced (OR=0.74, 95%CI 0.58 to 0.94). Injuries and illnesses, and their influence on training availability, during preparation are major determinants of an athlete's chance of performance goal success or failure at the international level. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  9. Spatially-explicit estimation of geographical representation in large-scale species distribution datasets.

    Science.gov (United States)

    Kalwij, Jesse M; Robertson, Mark P; Ronk, Argo; Zobel, Martin; Pärtel, Meelis

    2014-01-01

    Much ecological research relies on existing multispecies distribution datasets. Such datasets, however, can vary considerably in quality, extent, resolution or taxonomic coverage. We provide a framework for a spatially-explicit evaluation of geographical representation within large-scale species distribution datasets, using the comparison of an occurrence atlas with a range atlas dataset as a working example. Specifically, we compared occurrence maps for 3773 taxa from the widely-used Atlas Florae Europaeae (AFE) with digitised range maps for 2049 taxa of the lesser-known Atlas of North European Vascular Plants. We calculated the level of agreement at a 50-km spatial resolution using average latitudinal and longitudinal species range, and area of occupancy. Agreement in species distribution was calculated and mapped using Jaccard similarity index and a reduced major axis (RMA) regression analysis of species richness between the entire atlases (5221 taxa in total) and between co-occurring species (601 taxa). We found no difference in distribution ranges or in the area of occupancy frequency distribution, indicating that atlases were sufficiently overlapping for a valid comparison. The similarity index map showed high levels of agreement for central, western, and northern Europe. The RMA regression confirmed that geographical representation of AFE was low in areas with a sparse data recording history (e.g., Russia, Belarus and the Ukraine). For co-occurring species in south-eastern Europe, however, the Atlas of North European Vascular Plants showed remarkably higher richness estimations. Geographical representation of atlas data can be much more heterogeneous than often assumed. Level of agreement between datasets can be used to evaluate geographical representation within datasets. Merging atlases into a single dataset is worthwhile in spite of methodological differences, and helps to fill gaps in our knowledge of species distribution ranges. Species distribution

  10. Estimativa de área foliar da videira 'Niagara Rosada' conduzida em sistema de latada, região norte fluminense

    Directory of Open Access Journals (Sweden)

    Miquéias Permanhani

    2014-12-01

    Full Text Available Com o objetivo de estabelecer um modelo matemático para estimar de forma precisa a área foliar da videira 'Niagara Rosada' na região de Cardoso Moreira-RJ, realizou-se este trabalho em vinhedo particular do sítio pioneiro, implantado no ano de 2002, em sistema de latada. Foram coletadas aleatoriamente, no ciclo de produção iniciado em 2011, 70 folhas de diversos tamanhos, completamente expandidas e sem danos aparentes para determinar a relação entre a área foliar (AF e a área do círculo (AC, considerando seu diâmetro igual à largura da folha. Por meio da análise de regressão, obteve-se a equação linear (AFes = 0,82*AC + 16,12 que, juntamente com mais outras duas, foram utilizadas para comparar a área foliar estimada com a área foliar medida em 30 folhas do ciclo de produção posterior (Março de 2012. Constatou-se que as equações apresentadas permitem estimar de forma precisa a área foliar da videira 'Niagara Rosada/IAC 572' conduzida em sistema de latada, na região de Cardoso Moreira-RJ, com apenas uma dimensão foliar: a largura da folha, sendo que o modelo de regressão obtido (AFes = 0,82*AC + 16,12 foi o que menos subestimou a área da folha comparada (coeficiente angular = 0,99, seguido pelo modelo indicado por Pedro Jr. et al. (1986.

  11. Influence of chirality on the thermal and electric properties of the columnar mesophase exhibited by homomeric dipeptides

    Science.gov (United States)

    Parthasarathi, Srividhya; Shankar Rao, D. S.; Prabhu, Rashmi; Yelamaggad, C. V.; Krishna Prasad, S.

    2017-10-01

    We present the first investigation of the influence of chirality on the thermal and electric properties in a biologically important homomeric dipeptide that exhibits a hexagonal columnar liquid crystal mesophase. The peptide employed has two chiral centres, and thus the two possible enantiopures are the (R,R) and (S,S) forms having opposite chirality. The measurements reported the span of the binary phase space between these two enantiopures. Any point in the binary diagram is identified by the enantiomeric excess Xee (the excess content of the R,R enantiopure over its S,S counterpart). We observe that the magnitude of Xee plays a pivotal role in governing the properties as evidenced by X-ray diffraction (XRD), electric polarization (Ps), dielectric relaxation spectroscopy (DRS) measurements, and the isotropic-columnar transition temperature. For example, XRD shows that while other features pointing to a hexagonal columnar phase remain the same, additional short-range ordering, indicating correlated discs within the column, is present for the enantiopures (Xee = ±1) but not for the racemate (Xee = 0). Similarly, an electric-field driven switching whose profile suggests the phase structure to be antiferroelectric is seen over the entire binary space, but the magnitude is dependent on Xee; interestingly the polarization direction is axial, i.e., along the column axis. DRS studies display two dielectric modes over a limited temperature range and one mode (mode 2) connected with the antiferroelectric nature of the columnar structure covering the entire mesophase. The relaxation frequency and the thermal behaviour of mode 2 are strongly influenced by Xee. The most attractive effect of chirality is its influence on the polar order, a measure of which is the magnitude of the axial polarization. This result can be taken to be a direct evidence of the manifestation of molecular recognition and the delicate interplay between chiral perturbations and the magnitude of the

  12. History and Flight Devleopment of the Electrodynamic Dust Shield

    Science.gov (United States)

    Johansen, Michael R.; Mackey, Paul J.; Hogue, Michael D.; Cox, Rachel E.; Phillips, James R., III; Calle, Carlos I.

    2015-01-01

    The surfaces of the moon, Mars, and that of some asteroids are covered with a layer of dust that may hinder robotic and human exploration missions. During the Apollo missions, for example, lunar dust caused a number of issues including vision obscuration, false instrument readings, contamination, and elevated temperatures. In fact, some equipment neared failure after only 75 hours on the lunar surface due to effects of lunar dust. NASA's Kennedy Space Center has developed an active technology to remove dust from surfaces during exploration missions. The Electrodynamic Dust Shield (EDS), which consists of a series of embedded electrodes in a high dielectric strength substrate, uses a low power, low frequency signal that produces an electric field wave that travels across the surface. This non-uniform electric field generates dielectrophoretic and electrostatic forces capable of moving dust out of these surfaces. Implementations of the EDS have been developed for solar radiators, optical systems, camera lenses, visors, windows, thermal radiators, and fabrics The EDS implementation for transparent applications (solar panels, optical systems, windows, etc.) uses transparent indium tin oxide electrodes on glass or transparent lm. Extensive testing was performed in a roughly simulated lunar environment (one-sixth gravity at 1 mPa atmospheric pressure) with lunar simulant dust. EDS panels over solar radiators showed dust removal that restored solar panel output reaching values very close to their initial output. EDS implementations for thermal radiator protection (metallic spacecraft surfaces with white thermal paint and reflective films) were also extensively tested at similar high vacuum conditions. Reflectance spectra for these types of implementations showed dust removal efficiencies in the 96% to 99% range. These tests indicate that the EDS technology is now at a Technology Readiness Level of 4 to 5. As part of EDS development, a flight version is being prepared for

  13. Recovery Act: High-Temperature Circuit Boards for use in Geothermal Well Monitoring Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hooker, Matthew [Composite Tehcnology Development, Inc., Lafayette, CO (United States); Fabian, Paul [Composite Tehcnology Development, Inc., Lafayette, CO (United States)

    2013-05-01

    depths. At present, the highest-temperature commercially available circuit boards are based on polyimide materials, and those have maximum use temperatures of 200 to 250°C. In addition to thermal stability, downhole electronics must also be fabricated into high-aspect-ratio packages. For example, the multilayer assemblies produced at SNL were approximately 2.5 cm wide and 50 cm long. Because of this very high form factor, glass-fiber-reinforced polymers are much more desirable than multilayer ceramic modules (MCM). MCMs have many advantages for some applications, but are susceptible to damage induced by the mechanical and vibrational loads commonly experienced by data-logging tools. Thus, as EGS technology continues to advance, there is a strong need for multilayer electronics that can provide the necessary thermal performance while also being compatible with high-form-factor circuit designs. This project involved the design and development of high-temperature circuit materials, as well as the fabrication and testing of circuit components. The material development included the evaluation of various polymer/fiberglass composites, whereas the circuit components were tested using conventional microelectronic evaluation techniques. This effort targeted development of a new class of high-temperature multilayer circuit boards for use in downhole data-logging applications where temperatures are on the order of 300°C. This is consistent with DOE’s multiyear plan for advancing technologies for use in enhanced geothermal systems. Organic and inorganic polymer systems, both with glass reinforcements, were considered to provide the following performance at elevated temperatures: • Mechanical strength and durability • High dielectric strength and electrical resistivity • Thermal stability • Strong adhesion to copper to ensure the reliability of the multilayer assemblies • Processing characteristics that are consistent with state-of-the-art multilayer circuit board

  14. Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

    Science.gov (United States)

    Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

    2015-06-16

    dielectric strength, to produce two-dimensional nanosheets with atomic thickness that can be used as macromolecular building blocks in the assembly of nanocomposites. We describe how these advantageous properties turn LDHs into excellent vehicles for the preparation of multifunctional materials with increasing levels of complexity. For clarity, the reader will first find a succinct description of the most relevant aspects controlling the magnetism of LDHs followed by their use in the preparation of magnetic hybrids from a molecular perspective. This includes the intercalation anionic species of increasing nuclearity like paramagnetic mononuclear complexes, stimulus-responsive molecular guests, one- and two-dimensional coordination polymers, or even preassembled 2D networks. This approach allows us to evolve from "dual-function" materials with coexistence, for example, of magnetism and superconductivity, to smart materials in which the magnetic or structural properties of the LDH layers can be tuned by applying an external stimulus like light or temperature. We will conclude with a brief look into the promising features offered by magnetic nanocomposites based on LDHs and our views on the most promising directions to be pursued in this context.

  15. Energy storage in ceramic dielectrics

    International Nuclear Information System (INIS)

    Love, G.R.

    1990-01-01

    Historically, multilayer ceramic capacitors (MLC's) have not been considered for energy storage applications for two primary reasons. First, physically large ceramic capacitors were very expensive and, second, total energy density obtainable was not nearly so high as in electrolytic capacitor types. More recently, the fabrication technology for MLC's has improved significantly, permitting both significantly higher energy density and significantly lower costs. Simultaneously, in many applications, total energy storage has become smaller, and the secondary requirements of very low effective series resistance and effective series inductance (which, together, determine how efficiently the energy may be stored and recovered) have become more important. It is therefore desirable to reexamine energy storage in ceramics for contemporary commercial and near-commercial dielectrics. Stored energy is proportional to voltage squared only in the case of paraelectric insulators, because only they have capacitance that is independent of bias voltage. High dielectric constant materials, however, are ferroics (that is ferroelectric and/or antiferroelectric) and display significant variation of effective dielectric constant with bias voltage

  16. Flexible graphene–PZT ferroelectric nonvolatile memory

    International Nuclear Information System (INIS)

    Lee, Wonho; Ahn, Jong-Hyun; Kahya, Orhan; Toh, Chee Tat; Özyilmaz, Barbaros

    2013-01-01

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr 0.35 ,Ti 0.65 )O 3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol–gel methods, respectively. Such PZT films show a high remnant polarization (P r ) of 30 μC cm −2 and a coercive voltage (V c ) of 3.5 V under a voltage loop over ±11 V. The graphene–PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits. (paper)

  17. Wide and ultra-wide bandgap oxides: where paradigm-shift photovoltaics meets transparent power electronics

    Science.gov (United States)

    Pérez-Tomás, Amador; Chikoidze, Ekaterine; Jennings, Michael R.; Russell, Stephen A. O.; Teherani, Ferechteh H.; Bove, Philippe; Sandana, Eric V.; Rogers, David J.

    2018-03-01

    Oxides represent the largest family of wide bandgap (WBG) semiconductors and also offer a huge potential range of complementary magnetic and electronic properties, such as ferromagnetism, ferroelectricity, antiferroelectricity and high-temperature superconductivity. Here, we review our integration of WBG and ultra WBG semiconductor oxides into different solar cells architectures where they have the role of transparent conductive electrodes and/or barriers bringing unique functionalities into the structure such above bandgap voltages or switchable interfaces. We also give an overview of the state-of-the-art and perspectives for the emerging semiconductor β- Ga2O3, which is widely forecast to herald the next generation of power electronic converters because of the combination of an UWBG with the capacity to conduct electricity. This opens unprecedented possibilities for the monolithic integration in solar cells of both self-powered logic and power electronics functionalities. Therefore, WBG and UWBG oxides have enormous promise to become key enabling technologies for the zero emissions smart integration of the internet of things.

  18. BaTiO3-based nanolayers and nanotubes: first-principles calculations.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V; Kuruch, Dmitrii D

    2013-01-30

    The first-principles calculations using hybrid exchange-correlation functional and localized atomic basis set are performed for BaTiO(3) (BTO) nanolayers and nanotubes (NTs) with the structure optimization. Both the cubic and the ferroelectric BTO phases are used for the nanolayers and NTs modeling. It follows from the calculations that nanolayers of the different ferroelectric BTO phases have the practically identical surface energies and are more stable than nanolayers of the cubic phase. Thin nanosheets composed of three or more dense layers of (0 1 0) and (0 1 1[overline]) faces preserve the ferroelectric displacements inherent to the initial bulk phase. The structure and stability of BTO single-wall NTs depends on the original bulk crystal phase and a wall thickness. The majority of the considered NTs with the low formation and strain energies has the mirror plane perpendicular to the tube axis and therefore cannot exhibit ferroelectricity. The NTs folded from (0 1 1[overline]) layers may show antiferroelectric arrangement of Ti-O bonds. Comparison of stability of the BTO-based and SrTiO(3)-based NTs shows that the former are more stable than the latter. Copyright © 2012 Wiley Periodicals, Inc.

  19. Dynamic surface electronic reconstruction as symmetry-protected topological orders in topological insulator Bi2Se3

    Science.gov (United States)

    Shu, G. J.; Liou, S. C.; Karna, S. K.; Sankar, R.; Hayashi, M.; Chou, F. C.

    2018-04-01

    The layered narrow-band-gap semiconductor Bi2Se3 is composed of heavy elements with strong spin-orbital coupling, which has been identified both as a good candidate for a thermoelectric material with high thermoelectric figure of merit (Z T ) and as a topological insulator of the Z2 type with a gapless surface band in a Dirac-cone shape. The existence of a conjugated π -bond system on the surface of each Bi2Se3 quintuple layer is proposed based on an extended valence bond model with valence electrons distributed in the hybridized orbitals. Supporting experimental evidence of a two-dimensional (2D) conjugated π -bond system on each quintuple layer of Bi2Se3 is provided using electron energy-loss spectroscopy and electron density mapping through inverse Fourier transform of x-ray diffraction data. Quantum chemistry calculations support the π -bond existence between partially filled 4 pz orbitals of Se via side-to-side orbital overlap positively. The conjugated π -bond system on the surface of each quintuple Bi2Se3 layer is proposed to be similar to that found in graphite (graphene) and responsible for the unique 2D conduction mechanism. The van der Waals (vdW) attractive force between quintuple layers is interpreted to be coming from the antiferroelectrically ordered effective electric dipoles, which are constructed with π -bond trimer pairs on Se layers across the vdW gap of minimized Coulomb repulsion.

  20. Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

    Science.gov (United States)

    Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

    2011-09-01

    Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

  1. First-principles approach to the dynamic magnetoelectric couplings for the non-reciprocal directional dichroism in BiFeO3

    International Nuclear Information System (INIS)

    Lee, Jun Hee; Fishman, Randy S; Kézsmáki, István

    2016-01-01

    Due to the complicated magnetic and crystallographic structures of BiFeO 3 , its magnetoelectric (ME) couplings and microscopic model Hamiltonian remain poorly understood. By employing a first-principles approach, we uncover all possible ME couplings associated with the spin-current (SC) and exchange-striction (ES) polarizations, and construct an appropriate Hamiltonian for the long-range spin-cycloid in BiFeO 3 . First-principles calculations are used to understand the microscopic origins of the ME couplings. We find that inversion symmetries broken by ferroelectric and antiferroelectric distortions induce the SC and the ES polarizations, which cooperatively produce the dynamic ME effects in BiFeO 3 . A model motivated by first principles reproduces the absorption difference of counter-propagating light beams called non-reciprocal directional dichroism. The current paper focuses on the spin-driven (SD) polarizations produced by a dynamic electric field, i.e. the dynamic ME couplings. Due to the inertial properties of Fe, the dynamic SD polarizations differ significantly from the static SD polarizations. Our systematic approach can be generally applied to any multiferroic material, laying the foundation for revealing hidden ME couplings on the atomic scale and for exploiting optical ME effects in the next generation of technological devices such as optical diodes. (paper)

  2. Room temperature single-crystal diffuse scattering and ab initio lattice dynamics in CaTiSiO5.

    Science.gov (United States)

    Gutmann, M J; Refson, K; Zimmermann, M V; Swainson, I P; Dabkowski, A; Dabkowska, H

    2013-08-07

    Single-crystal diffuse scattering data have been collected at room temperature on synthetic titanite using both neutrons and high-energy x-rays. A simple ball-and-springs model reproduces the observed diffuse scattering well, confirming its origin to be primarily due to thermal motion of the atoms. Ab initio phonons are calculated using density-functional perturbation theory and are shown to reproduce the experimental diffuse scattering. The observed diffuse x-ray and neutron scattering patterns are consistent with a summation of mode frequencies and displacement eigenvectors associated with the entire phonon spectrum, rather than with a simple, short-range static displacement. A band gap is observed between 600 and 700 cm(-1) with only two modes crossing this region, both associated with antiferroelectric Ti-O motion along a. One of these modes (of Bu symmetry), displays a large LO-TO mode-splitting (562-701.4 cm(-1)) and has a dominant component coming from Ti-O bond-stretching and, thus, the mode-splitting is related to the polarizability of the Ti-O bonds along the chain direction. Similar mode-splitting is observed in piezo- and ferroelectric materials. The calculated phonon dispersion model may be of use to others in future to understand the phase transition at higher temperatures, as well as in the interpretation of measured phonon dispersion curves.

  3. Synthesis, macroscopic and local probe characterization of AgCrO$_2$ and CdCr$_2$S$_4$

    CERN Document Server

    Oliveira, Gonçalo; Araujo, J P

    The search of new materials with new and/or enhanced physical properties has, nowadays, a strict relation with the evolution of technology. The hunt for systems exhibiting simultaneous (anti)ferroelectric and (anti)ferromagnetic orders has re-started in the last years, and remains as one of the hot topics for Physic, Chemistry and Materials Science scientific communities. This is triggered by the possibility to apply these materials into, ${e.g.}$, new multiferroic memories that could be written electrically and read magnetically (or vice-versa). This thesis presents an experimental study on two of these so-called multiferroic materials, the AgCrO$_2$ delafossite and CdCr$_2$S$_4$ spinel type compounds. Different methods have been tested for the synthesis of delafossite silver chromium oxide AgCrO$_2$ namely, solid state reaction (ssr) and sol-gel combustion. The processes were optimized regarding complexing/combusting agents, temperature and duration of the heat treatments, as well as the processing atmosphe...

  4. Instability of the layered orthorhombic post-perovskite phase of SrTiO3 and other candidate orthorhombic phases under pressure

    Science.gov (United States)

    Bhandari, Churna; Lambrecht, Walter R. L.

    2018-06-01

    While the tetragonal antiferro-electrically distorted (AFD) phase with space group I 4 / mcm is well known for SrTiO3 to occur below 105 K, there are also some hints in the literature of an orthorhombic phase, either at the lower temperature or at high pressure. A previously proposed orthorhombic layered structure of SrTiO3, known as the post-perovskite or CaIrO3 structure with space group Cmcm is shown to have significantly higher energy than the cubic or tetragonal phase and to have its minimum volume at larger volume than cubic perovskite. The Cmcm structure is thus ruled out. We also study an alternative Pnma phase obtained by two octahedral rotations about different axes. This phase is found to have slightly lower energy than the I 4 / mcm phase in spite of the fact that its parent, in-phase tilted P 4 / mbm phase is not found to occur. Our calculated enthalpies of formation show that the I 4 / mcm phase occurs at slightly higher volume than the cubic phase and has a negative transition pressure relative to the cubic phase, which suggests that it does not correspond to the high-pressure tetragonal phase. The enthalpy of the Pnma phase is almost indistinguishable from the I 4 / mcm phase. Alternative ferro-electric tetragonal and orthorhombic structures previously suggested in literature are discussed.

  5. Dielectric spectroscopy of the SmQ* phase

    Science.gov (United States)

    Perkowski, P.; Bubnov, A.; Piecek, W.; Ogrodnik, K.; Hamplová, V.; Kašpar, M.

    2011-11-01

    Liquid crystal possessing two biphenyl moieties in the molecular core and lateral chlorine substitution far from the chiral chain has been studied by dielectric spectroscopy. On cooling from the isotropic phase, the material possesses the frustrated smectic Q* (SmQ*) and SmCA* phases. It has been confirmed by dielectric spectroscopy that the SmQ* phase can be related to the SmCA* anti-ferroelectric phase. However, only one relaxation process has been observed in the SmQ* phase, while in the SmCA*, two relaxations are clearly detectable. It seems that the mode found in the SmQ* can be connected with high-frequency anti-phase mode observed in the SmCA* phase. Its relaxation frequency is similar to PH relaxation frequency, but is weaker. The same relaxation has been observed even a few degrees above the SmQ*-Iso phase transition. Another explanation for the mode detected in SmQ* and isotropic phases can be molecular motions around short molecular axis.

  6. Neutron and x-ray scattering studies of ferroelectric phase transitions

    International Nuclear Information System (INIS)

    Dolling, G.

    1982-08-01

    The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students

  7. Phase transitions to dipolar clusters and charge density waves in high T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Saarela, M., E-mail: Mikko.Saarela@oulu.fi [Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 (Finland); Kusmartsev, F.V. [Department of Physics, Loughborough University, LE11 3TU (United Kingdom)

    2017-02-15

    We show that doping of hole charge carriers leads to formation of electric dipolar clusters in cuprates. They are created by many-body interactions between the dopant ion outside and holes inside the CuO planes. Because of the two-fold degeneracy holes in the CuO plane cluster into four-particles resonance valence bond plaquettes bound with dopant ions. Such dipoles may order into charge-density waves (CDW) or stripes or form a disordered state depending on doping and temperature. The lowest energy of the ordered system corresponds to a local anti-ferroelectric ordering. The mobility of individual disordered dipoles is very low at low temperatures and they prefer first to bind into dipole-dipole pairs. Electromagnetic radiation interacts strongly with electric dipoles and when the sample is subjected to it the mobility changes significantly. This leads to a fractal growth of dipolar clusters. The existence of electric dipoles and CDW induce two phase transitions with increasing temperature, melting of the ordered state and disappearance of the dipolar state. Ferroelectricity at low doping is a natural consequence of such dipole moments. We develop a theory based on two-level systems and dipole-dipole interaction to explain the behavior of the polarization as a function of temperature and electric field.

  8. Flexible graphene-PZT ferroelectric nonvolatile memory.

    Science.gov (United States)

    Lee, Wonho; Kahya, Orhan; Toh, Chee Tat; Ozyilmaz, Barbaros; Ahn, Jong-Hyun

    2013-11-29

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr0.35,Ti0.65)O3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol–gel methods, respectively. Such PZT films show a high remnant polarization (Pr) of 30 μC cm−2 and a coercive voltage (Vc) of 3.5 V under a voltage loop over ±11 V. The graphene–PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits.

  9. NQR investigation and characterization of cocrystals and crystal polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Seliger, Janez, E-mail: janez.seliger@fmf.uni-lj.si; Zagar, Veselko [Jozef Stefan Institute (Slovenia); Asaji, Tetsuo [Nihon University, Department of Chemistry, College of Humanities and Sciences (Japan)

    2013-05-15

    The application of {sup 14}N NQR to the study of cocrystals and crystal polymorphs is reviewed. In ferroelectric and antiferroelectric organic cocrystals {sup 14}N NQR is used to determine proton position in an N-H...O hydrogen bond and proton displacement below T{sub C}. In cocrystal isonicitinamide - oxalic acid (2:1) {sup 14}N NQR is used to distinguish between two polymorphs and to determine the type of the hydrogen bond (N{sup -}...H-O). The difference in the {sup 14}N NQR spectra of cocrystal formers and cocrystal is investigated in case of carbamazepine, saccharin and carbamazepine - saccharin (1:1). The experimental resolution allows an unambiguous distinction between the {sup 14}N NQR spectrum of the cocrystal and the {sup 14}N NQR spectra of the cocrystal formers. The possibility of application of NQR and double resonance for the determination of the inhomogeneity of the sample and for the study of the life time of an unstable polymorph is discussed.

  10. New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction; Nouvelles etudes structurales de cristaux liquides par reflectivite et diffraction resonante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, P

    2007-04-15

    This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B{sub 2} liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B{sub 2} phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation.

  11. New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction

    International Nuclear Information System (INIS)

    Fernandes, P.

    2007-04-01

    This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B 2 liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B 2 phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation

  12. Phase transition scheme of isolated hydrogen-bonded material h-MeHPLN studied by neutron and X-ray diffraction

    International Nuclear Information System (INIS)

    Kiyanagi, Ryoji; Kimura, Hiroyuki; Watanabe, Masashi; Noda, Yukio; Kojima, Akiko; Mochida, Tomoyuki; Sugawara, Tadashi

    2005-01-01

    The antiferroelectric material with an isolated hydrogen-bond, h-MeHPLN (5-methyl-9-hydroxyphenalenon), was structurally investigated by X-ray and neutron diffraction experiments in the low-temperature phase (T c =42K). The formation of a superlattice of 2 x b was found below T c , and the space group was identified to be P2 1 /c transformed from C2 c . Accordingly, the number of crystallographically independent molecules became two. The electron density distribution and the nuclear density distribution revealed some significant features below T c . One of the independent molecules exhibits an ordering of the hydrogen atom in the hydrogen-bond region, a conformational ordering of the methyl group and a molecular rotation around the a-axis. Moreover, a static electronic dipole moment is found in the hydrogen-bond region in this molecule. In contrast, the other molecule shows a disordered hydrogen atom, disordered conformation of the methyl group, no molecular rotation and a disordered electronic dipole moment. These features can be described simply in terms of a modulation wave of an order parameter. (author)

  13. Chemical approach to neutral-ionic valence instability, quantum phase transition, and relaxor ferroelectricity in organic charge-transfer complexes

    International Nuclear Information System (INIS)

    Horiuchi, Sachio; Kumai, Reiji; Okimoto, Yoichi; Tokura, Yoshinori

    2006-01-01

    Neutral-ionic (NI) phase transition is a reversible switching of organic charge-transfer complexes between distinct valence states by external stimuli. This phase transformation in the low-dimensional system is demonstrated to provide a variety of novel dielectric, structural, and electronic properties. Importantly, ionization of the electron donor-acceptor pairs is usually accompanied by a ferroelectric or antiferroelectric order of the molecular lattice, leading to huge dielectric response near the transition point. Although these characteristics are potentially useful for future electronic and optical applications, the thermally accessible NI transition (TINIT) is still an extremely rare case. The TINIT compounds including some new materials are overviewed in order to provide convenient guides to their design and experimental identifications. The phase transition and dielectric properties can be closely controlled in various ways depending on chemical and physical modifications of the crystals. Among them, a quantum phase transition and relaxor ferroelectricity, both of which are currently attracting subjects from both scientific and practical perspectives, are highlighted as the first achievements in organic charge-transfer complexes

  14. The role of order-disorder transitions in the quest for molecular multiferroics: structural and magnetic neutron studies of a mixed valence iron(II)-iron(III) formate framework.

    Science.gov (United States)

    Cañadillas-Delgado, Laura; Fabelo, Oscar; Rodríguez-Velamazán, J Alberto; Lemée-Cailleau, Marie-Hélène; Mason, Sax A; Pardo, Emilio; Lloret, Francesc; Zhao, Jiong-Peng; Bu, Xian-He; Simonet, Virginie; Colin, Claire V; Rodríguez-Carvajal, Juan

    2012-12-05

    Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH(2)(CH(3))(2)](n)[Fe(III)Fe(II)(HCOO)(6)](n). The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities of the [Fe(III)Fe(II)(HCOO)(6)](n) framework. In the low-temperature phase, a change in space group from P31c to R3c occurs, involving a tripling of the c-axis due to the ordering of the dimethylammonium counterion. The occurrence of this nuclear phase transition is associated with an electric transition, from paraelectric to antiferroelectric. A combination of powder and single crystal neutron diffraction measurements below the magnetic order transition (ca. 37 K) has been used to determine unequivocally the magnetic structure of this Néel N-Type ferrimagnet, proving that the ferrimagnetic behavior is due to a noncompensation of the different Fe(II) and Fe(III) magnetic moments.

  15. Atomic scale imaging of competing polar states in a Ruddlesden–Popper layered oxide

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J.; Schlom, Darrell G.; Alem, Nasim; Gopalan, Venkatraman

    2016-01-01

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden–Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure. PMID:27578622

  16. Atomic scale imaging of competing polar states in a Ruddlesden-Popper layered oxide.

    Science.gov (United States)

    Stone, Greg; Ophus, Colin; Birol, Turan; Ciston, Jim; Lee, Che-Hui; Wang, Ke; Fennie, Craig J; Schlom, Darrell G; Alem, Nasim; Gopalan, Venkatraman

    2016-08-31

    Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in Ruddlesden-Popper (RP), An+1BnO3n+1, thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ångstrom resolution in Srn+1TinO3n+1 thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure.

  17. Intrinsic Ferroelasticity and/or Multiferroicity in Two-Dimensional Phosphorene and Phosphorene Analogues.

    Science.gov (United States)

    Wu, Menghao; Zeng, Xiao Cheng

    2016-05-11

    Phosphorene and phosphorene analogues such as SnS and SnSe monolayers are promising nanoelectronic materials with desired bandgap, high carrier mobility, and anisotropic structures. Here, we show first-principles calculation evidence that these monolayers are potentially the long-sought two-dimensional (2D) materials that can combine electronic transistor characteristic with nonvolatile memory readable/writeable capability at ambient condition. Specifically, phosphorene is predicted to be a 2D intrinsic ferroelastic material with ultrahigh reversible strain, whereas SnS, SnSe, GeS, and GeSe monolayers are multiferroic with coupled ferroelectricity and ferroelasticity. Moreover, their low-switching barriers render room-temperature nonvolatile memory accessible, and their notable structural anisotropy enables ferroelastic or ferroelectric switching readily readable via electrical, thermal, optical, mechanical, or even spintronic detection upon the swapping of the zigzag and armchair direction. In addition, it is predicted that the GeS and GeSe monolayers as well as bulk SnS and SnSe can maintain their ferroelasticity and ferroelectricity (anti-ferroelectricity) beyond the room temperature, suggesting high potential for practical device application.

  18. Ferroelectric glass of spheroidal dipoles with impurities: polar nanoregions, response to applied electric field, and ergodicity breakdown

    International Nuclear Information System (INIS)

    Takae, Kyohei; Onuki, Akira

    2017-01-01

    Using molecular dynamics simulation, we study dipolar glass in crystals composed of slightly spheroidal, polar particles and spherical, apolar impurities between metal walls. We present physical pictures of ferroelectric glass, which have been observed in relaxors, mixed crystals (such as KCN x KBr 1−x ), and polymers. Our systems undergo a diffuse transition in a wide temperature range, where we visualize polar nanoregions (PNRs) surrounded by impurities. In our simulation, the impurities form clusters and their space distribution is heterogeneous. The polarization fluctuations are enhanced at relatively high T depending on the size of the dipole moment. They then form frozen PNRs as T is further lowered into the nonergodic regime. As a result, the dielectric permittivity exhibits the characteristic features of relaxor ferroelectrics. We also examine nonlinear response to cyclic applied electric field and nonergodic response to cyclic temperature changes (ZFC/FC), where the polarization and the strain change collectively and heterogeneously. We also study antiferroelectric glass arising from molecular shape asymmetry. We use an Ewald scheme of calculating the dipolar interaction in applied electric field. (paper)

  19. Effect of La doping on the ferroic order in Pb-based perovskite-type relaxor ferroelectrics

    Science.gov (United States)

    Maier, B. J.; Welsch, A.-M.; Mihailova, B.; Angel, R. J.; Zhao, J.; Paulmann, C.; Engel, J. M.; Marshall, W. G.; Gospodinov, M.; Petrova, D.; Bismayer, U.

    2011-04-01

    The structural alteration induced by the substitution of three-valent cations with an isotropic electronic outermost shell for Pb2+ in perovskite-type relaxors was investigated in the solid solutions Pb1-xLaxSc(1+x)/2Ta(1-x)/2O3, x =0.08 (PST-La) and Pb1-xLaxSc(1+x)/2Nb(1-x)/2O3, x =0.23 (PSN-La). In order to distinguish the “charge” effects from “strain” effects associated with the incorporation of La3+ in the structure, Sr-containing PbSc0.5Nb0.5O3 was characterized as well. The structure of the compounds was analyzed by in situ Raman spectroscopy, single-crystal x-ray diffraction, and powder neutron diffraction at different temperatures or pressures. It is shown that the embedding of La3+ strongly affects the ferroic structural species due to strain effects through a disturbance of the system of lone-pair electrons associated with Pb2+ and a decrease in the tolerance factor. La doping suppresses the dynamical coupling between off-centered Pb and B-site cations and enhances antiphase BO6 octahedral tilting which, depending on the level of doping, may lead to long-range order of antiphase BO6 tilts at ambient conditions and frustrated antiferroelectric order of Pb ions at low temperatures.

  20. Electrical properties of a novel lead alkoxide precursor: Lead glycolate

    International Nuclear Information System (INIS)

    Tangboriboon, Nuchnapa; Pakdeewanishsukho, Kittikhun; Jamieson, Alexander; Sirivat, Anuvat; Wongkasemjit, Sujitra

    2006-01-01

    The reaction of lead acetate trihydrate Pb(CH 3 COO) 2 .3H 2 O and ethylene glycol, using triethylenetetramine (TETA) as a catalyst, provides in one step access to a polymer-like precursor of lead glycolate [-PbOCH 2 CH 2 O-]. On the basis of high-resolution mass spectroscopy, chemical analysis composition, FTIR, 13 C-solid state NMR and TGA, the lead glycolate precursor can be identified as a trimer structure. The FTIR spectrum demonstrates the characteristics of lead glycolate; the peaks at 1086 and 1042 cm -1 can be assigned to the C-O-Pb stretchings. The 13 C-solid state NMR spectrum gives notably only one peak at 68.639 ppm belonging to the ethylene glycol ligand. The phase transformations of lead glycolate and lead acetate trihydrate to lead oxide, their microstructures, and electrical properties were found to vary with increasing temperature. The lead glycolate precursor has superior electrical properties relative to those of lead acetate trihydrate, suggesting that the lead glycolate precursor can possibly be used as a starting material for producing electrical and semiconducting ceramics, viz. ferroelectric, anti-ferroelectric, and piezoelectric materials

  1. B-site substituted solid solutions on the base of sodium-bismuth titanate

    Directory of Open Access Journals (Sweden)

    V. M. Ishchuk

    2016-12-01

    Full Text Available The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(Na0.5Bi0.50.80Ba0.20](Ti1–yByO3 system of solid solutions with B-site substitutions. The substitutions by zirconium, tin and ion complexes (In0.5Nb0.5 and (Fe0.5Nb0.5 have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures. Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000–1100∘C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.

  2. Hydrostatic pressure effects on the dielectric response of potassium cyanide

    International Nuclear Information System (INIS)

    Ortiz Lopez, J.

    1992-01-01

    The complex dielectric constant of crystalline KCN was measured under hydrostatic pressures up to 6.1 kbar in the temperature and frequency ranges of 50-300 K and 10-10 5 Hz, respectively. It is found that the pressure derivative of the real part of the dielectric constant at all measured temperatures is negative. From these results we obtain estimates for the pressure and volume derivatives of polarizabilities. The anomaly in the real part of the dielectric constant at the elastic order-disorder transition shifts to higher temperatures with increasing pressure at a rate of 2.05 K/kbar. By carefully avoiding thermal cycling through this transition we find no evidence of the monoclinic phase reported to exist in the P-T phase diagram of KCN at relatively low pressures. Dielectric loss measurements show thermally-activated CN - reorientation rates in the elastically ordered phase with pressure-independent reorientational barriers and decreasing attempt frequencies for increasing pressures. Additional pressure effects on dielectric loss allow to obtain the pressure derivative of the antiferroelectric transition temperature as 1.97 K/kbar. (Author)

  3. Quantum electric-dipole liquid on a triangular lattice.

    Science.gov (United States)

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F; Sun, Young

    2016-02-04

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics.

  4. Phase transitions to dipolar clusters and charge density waves in high T_c superconductors

    International Nuclear Information System (INIS)

    Saarela, M.; Kusmartsev, F.V.

    2017-01-01

    We show that doping of hole charge carriers leads to formation of electric dipolar clusters in cuprates. They are created by many-body interactions between the dopant ion outside and holes inside the CuO planes. Because of the two-fold degeneracy holes in the CuO plane cluster into four-particles resonance valence bond plaquettes bound with dopant ions. Such dipoles may order into charge-density waves (CDW) or stripes or form a disordered state depending on doping and temperature. The lowest energy of the ordered system corresponds to a local anti-ferroelectric ordering. The mobility of individual disordered dipoles is very low at low temperatures and they prefer first to bind into dipole-dipole pairs. Electromagnetic radiation interacts strongly with electric dipoles and when the sample is subjected to it the mobility changes significantly. This leads to a fractal growth of dipolar clusters. The existence of electric dipoles and CDW induce two phase transitions with increasing temperature, melting of the ordered state and disappearance of the dipolar state. Ferroelectricity at low doping is a natural consequence of such dipole moments. We develop a theory based on two-level systems and dipole-dipole interaction to explain the behavior of the polarization as a function of temperature and electric field.

  5. Synergic nature of dielectric relaxation process in the layered perovskite halide salts: The case of 1,3- diammoniumpropylenetetrabromocadmate compound

    Science.gov (United States)

    Staśkiewicz, Beata

    2018-06-01

    The negative thermal expansion (NTE) property was a prototype to discuss the origin of difference between classical Debye relaxation process and the non-Debye behavior in the layered perovskite halide salt of chemical formula NH3(CH2)3NH3CdBr4. The analysis has been taken by dielectric relaxation spectroscopy measurements in almost six decades in frequency 5 × 102 ≤ f(ω) ≤ 1.2 × 108 and in the temperature range 315 ≤ T(K) ≤ 390. It was shown that the investigated sample exhibit an antiferrodistortive nature of phase transition between two orthorhombic structural modifications i.e. Pnma (phase I) and Ima2 (phase II) at Tc1(I → II) = 326 K, leading from an antiferroelectric to a paraelectric phase. The involvement of an odd number of carbon atoms in the alkylammonium chains in dielectric properties of examined sample is proved. Higher structural modifications, i.e. Ima2 (phase II) and P21/m (phase III), have shown significant deviations from a regular circle on the Cole-Cole diagram. Presented experimental observations are essentially important for the theoretical explanation of relaxation processes in analyzed organic - inorganic compound crystallizing in a perovskite-like topology and may provide new perspective on the fundamental aspect of relaxation response in "diammonium" series.

  6. Tunable ferroelectric polarization and its interplay with spin-orbit coupling in tin iodide perovskites

    Science.gov (United States)

    Stroppa, Alessandro; di Sante, Domenico; Barone, Paolo; Bokdam, Menno; Kresse, Georg; Franchini, Cesare; Whangbo, Myung-Hwan; Picozzi, Silvia

    2014-12-01

    Ferroelectricity is a potentially crucial issue in halide perovskites, breakthrough materials in photovoltaic research. Using density functional theory simulations and symmetry analysis, we show that the lead-free perovskite iodide (FA)SnI3, containing the planar formamidinium cation FA, (NH2CHNH2)+, is ferroelectric. In fact, the perpendicular arrangement of FA planes, leading to a ‘weak’ polarization, is energetically more stable than parallel arrangements of FA planes, being either antiferroelectric or ‘strong’ ferroelectric. Moreover, we show that the ‘weak’ and ‘strong’ ferroelectric states with the polar axis along different crystallographic directions are energetically competing. Therefore, at least at low temperatures, an electric field could stabilize different states with the polarization rotated by π/4, resulting in a highly tunable ferroelectricity appealing for multistate logic. Intriguingly, the relatively strong spin-orbit coupling in noncentrosymmetric (FA)SnI3 gives rise to a co-existence of Rashba and Dresselhaus effects and to a spin texture that can be induced, tuned and switched by an electric field controlling the ferroelectric state.

  7. Possible antipolar pairing mechanism in high-temperature superconductors

    International Nuclear Information System (INIS)

    Cardwell, D.A.; Shorrocks, N.M.

    1989-01-01

    An antipolar pairing mechanism for free charge carriers in high-T c superconducting compounds is proposed qualitatively. This involves the establishment of a two-dimensional (2D) array of effective charge-coupling centers within the superconducting lattice via a specific phonon distortion of cation species along a nonmajor crystallographic direction. A fundamental requirement of this model is that the density of such coupling centers decreases with decreasing temperature. In the case of Y-Ba-Cu-O, it is asserted that charge carriers in a 2D oxygen band adjacent to the phonon-containing plane become localized by the resulting (local) field distortion. Cooper pairs may then form when the charge-coupling-center density falls below the charge-carrier density. Such a mechanism could be mediated by a longitudinal phonon which softens at low temperatures to produce an antipolar state, such as that incipient to an antiferroelectric distortion of the lattice (i.e., in the zero-frequency limiting case). This model, which may be investigated experimentally by low-temperature Raman spectroscopy, isotopic substitution, and x-ray diffractometry at 4.2 K, can be applied to all p-type high-T c systems. In addition, it may account for the observed lattice anisotropy and short coherence length characteristic of these materials

  8. Some lessons and thoughts from development of an old-fashioned high-resolution atmospheric general circulation model

    Science.gov (United States)

    Ohfuchi, Wataru; Enomoto, Takeshi; Yoshioka, Mayumi K.; Takaya, Koutarou

    2014-05-01

    Some high-resolution simulations with a conventional atmospheric general circulation model (AGCM) were conducted right after the first Earth Simulator started operating in the spring of 2002. More simulations with various resolutions followed. The AGCM in this study, AFES (Agcm For the Earth Simulator), is a primitive equation spectral transform method model with a cumulus convection parameterization. In this presentation, some findings from comparisons between high and low-resolution simulations, and some future perspectives of old-fashioned AGCMs will be discussed. One obvious advantage of increasing resolution is capability of resolving the fine structures of topography and atmospheric flow. By increasing resolution from T39 (about 320 km horizontal grid interval) to T79 (160 km), to T159 (80 km) to T319 (40 km), topographic precipitation over Japan becomes increasingly realistic. This feature is necessary for climate and weather studies involving both global and local aspects. In order to resolve submesoscale (about 100 km horizontal scale) atmospheric circulation, about 10-km grid interval is necessary. Comparing T1279 (10 km) simulations with T319 ones, it is found that, for example, the intensity of heavy rain associated with Baiu front and the central pressure of typhoon become more realistic. These realistic submesoscale phenomena should have impact on larger-sale flow through dynamics and thermodynamics. An interesting finding by increasing horizontal resolution of a conventional AGCM is that some cumulus convection parameterizations, such as Arakawa-Schubert type scheme, gradually stop producing precipitation, while some others, such as Emanuel type, do not. With the former, the grid condensation increases with the model resolution to compensate. Which characteristics are more desirable is arguable but it is an important feature one has to consider when developing a high-resolution conventional AGCM. Many may think that conventional primitive equation

  9. Produção de massa seca, relação folha/colmo e alguns índices de crescimento do Brachiaria brizantha cv. Xaraés cultivado com a combinação de doses de nitrogênio e potássio Dry matter production, leaf/stem ratio and growth indexes of palisade grass (Brachiaria brizantha cv. Xaraés, cultivated with different rate combinations of nitrogen and potassium

    Directory of Open Access Journals (Sweden)

    Rosane Cláudia Rodrigues

    2008-03-01

    Full Text Available Objetivou-se avaliar a produção de massa seca das folhas, a relação folha/colmo e alguns índices de crescimento do capim-xaraés submetido a doses de nitrogênio (N e potássio (K. O experimento foi conduzido em casa-de-vegetação no período de novembro/2004 a fevereiro/2005. Adotou-se esquema fatorial 4 ´ 3, perfazendo 12 combinações, as quais foram distribuídas em delineamento experimental inteiramente casualizado, com quatro repetições, perfazendo um total 48 unidades experimentais. Foram utilizadas quatro doses de N (0, 75, 150 e 225 mg dm-3 e três doses de K (0, 50 e 100 mg dm-3. Verificou-se efeito das doses de N na produção de massa seca das folhas e na produção de massa seca total, em todos os cortes, com maior produção nas doses mais elevadas de N, ao passo que o K influenciou essas variáveis apenas no segundo corte. A relação folha/colmo, a RAF, a AFE e a RPF somente foram significativas no terceiro corte da planta. Os efeitos das doses de foram decrescentes sobre essas variáveis, enquanto as doses de K agiram de modo antagônico às doses de N sobre a RAF e AFE.This work aimed to evaluate dry matter production, leaf/stem ratio and growth indexes of palisade grass cv. Xaraés grown under increasing nitrogen and potassium rates. The experiment was carried out in a greenhouse from November, 2004 until February, 2005. The experimental treatments consisted of a 4 ´ 3 factorial arrangement between nitrogen and potassium rates respectively. Nitrogen rates were 0, 75, 150, and 225 mg dm-3, whereas potassium rates were 0; 50 and 100 mg dm-3. The experiment design was completely randomized with four replications. It was verified a positive N fertilization effect both on leaf dry matter yield and total dry matter yield. Potassium influenced these same response variables only at the second harvest. The leaf/stem ratio, leaf area ratio (LAR, specific leaf area (SLA and, leaf weight ratio (LWR were affected by treatments

  10. Reducing radiation dose to the female breast during conventional and dedicated breast computed tomography

    Science.gov (United States)

    Rupcich, Franco John

    The purpose of this study was to quantify the effectiveness of techniques intended to reduce dose to the breast during CT coronary angiography (CTCA) scans with respect to task-based image quality, and to evaluate the effectiveness of optimal energy weighting in improving contrast-to-noise ratio (CNR), and thus the potential for reducing breast dose, during energy-resolved dedicated breast CT. A database quantifying organ dose for several radiosensitive organs irradiated during CTCA, including the breast, was generated using Monte Carlo simulations. This database facilitates estimation of organ-specific dose deposited during CTCA protocols using arbitrary x-ray spectra or tube-current modulation schemes without the need to run Monte Carlo simulations. The database was used to estimate breast dose for simulated CT images acquired for a reference protocol and five protocols intended to reduce breast dose. For each protocol, the performance of two tasks (detection of signals with unknown locations) was compared over a range of breast dose levels using a task-based, signal-detectability metric: the estimator of the area under the exponential free-response relative operating characteristic curve, AFE. For large-diameter/medium-contrast signals, when maintaining equivalent AFE, the 80 kV partial, 80 kV, 120 kV partial, and 120 kV tube-current modulated protocols reduced breast dose by 85%, 81%, 18%, and 6%, respectively, while the shielded protocol increased breast dose by 68%. Results for the small-diameter/high-contrast signal followed similar trends, but with smaller magnitude of the percent changes in dose. The 80 kV protocols demonstrated the greatest reduction to breast dose, however, the subsequent increase in noise may be clinically unacceptable. Tube output for these protocols can be adjusted to achieve more desirable noise levels with lesser dose reduction. The improvement in CNR of optimally projection-based and image-based weighted images relative to photon

  11. New polyanion-based cathode materials for alkali-ion batteries

    Science.gov (United States)

    Yaghoobnejad Asl, Hooman

    A number of new materials have been discovered through exploratory synthesis with the aim to be studied as the positive electrode (cathode) in Li-ion and Na-ion batteries. The focus has been set on the ease of synthesis, cost and availability of active ingredients in the battery, and decent cycle-life performance through a combination of iron and several polyanionic ligands. An emphasis has been placed also on phosphite (HPO32-) as a polyanionic ligand, mainly due to the fact that it has not been studied seriously before as a polyanion for cathode materials. The concept of mixed polyanions, for example, boro-phosphate and phosphate-nitrates were also explored. In each case the material was first made and purified via different synthetic strategies, and the crystal structure, which dominantly controls the performance of the materials, has been extensively studied through Single-Crystal X-ray Diffraction (SCXRD) or synchrotron-based Powder X-ray Diffraction (PXRD). This investigation yielded four new compositions, namely Li3Fe 2(HPO3)3Cl, LiFe(HPO3)2, Li0.8Fe(H2O)2B[P2O8]•H 2O and AFePO4NO3 (A = NH4/Li, K). Furthermore, for each material the electrochemical performance for insertion of Li+ ion has been studied by means of various electrochemical techniques to reveal the nature of alkali ion insertion. In addition Na-ion intercalation has been studied for boro-phosphate and AFePO4NO3. Additionally a novel synthesis procedure has been reported for tavorite LiFePO4F 1-x(OH)x, where 0 ≤ x ≤ 1, an important class of cathode materials. The results obtained clearly demonstrate the importance of crystal structure on the cathode performance through structural and compositional effects. Moreover these findings may contribute to the energy storage community by providing insight into the solid-state science of electrode material synthesis and proposing new alternative compositions based on sustainable materials.

  12. ANÁLISE DO CRESCIMENTO DE RABANETE EM FUNÇÃO DE PERÍODOS DE CONVIVÊNCIA COM PLANTAS DANINHAS

    Directory of Open Access Journals (Sweden)

    Valdere Martins dos Santos

    2015-07-01

    Full Text Available Neste trabalho, objetivou-se avaliar a influência de períodos de convivência com plantas daninhas nas respostas morfofisiológicas de plantas de rabanete cultivado no sul do Estado do Tocantins. O delineamento experimental utilizado foi em blocos ao acaso, sendo seis tratamentos e quatro repetições. Foram avaliados 6 períodos de convivência com plantas daninhas em cinco épocas de avaliação (5, 10, 15, 21 e 30 dias após a emergência. Foram determinadas a taxa de crescimento da cultura (TCC, taxa de crescimento relativo (TCR, taxa de assimilação líquida (TAL, taxa de crescimento absoluto (TCA, razão de área foliar (RAF e área foliar específica (AFE. As TCC e TCR apresentaram uma fase inicial com rápido acúmulo de massa, até seu ponto máximo no 2o intervalo de crescimento, posteriormente, declínio devido ao período de senescência da cultura. A TAL atingiu seu crescimento máximo no 3o intervalo, verificando-se a seguir redução, com exceção dos tratamentos (sem competição e sem competição a partir do 5o dia que apresentaram aumento durante todo o ciclo da cultura. Resposta semelhante foi observada também para TCA. Para RAF e AFE verifica-se que nos tratamentos com algum período de competição ocorreu incremento até os 17 DAE dias, seguida por redução mais acentuada até os 30 DAE. As características morfofisiológicas são influenciadas pela competição com plantas daninhas.

  13. Análisis del crecimiento de lechuga (Lactuca sativa L. ‘Batavia’ cultivada en un suelo salino de la Sabana de Bogotá

    Directory of Open Access Journals (Sweden)

    Carranza Carlos

    2009-04-01

    Full Text Available

    La salinidad es una limitante en cultivos hortícolas a nivel mundial, que ocasiona alteraciones en el crecimiento, baja absorción y distribución de nutrientes a diferentes órganos de la planta y cambios en la calidad. El análisis de crecimiento en especies hortícolas como la lechuga establecido en un suelo salino no había sido estudiado con profundidad en la Sabana de Bogotá. El experimento se realizó en el Centro Agropecuario Marengo de la Universidad Nacional de Colombia, ubicado en el km 12 vía Bogotá-Mosquera. En tres parcelas de 300 m2 cada una, con 8,3 plantas/m2, regadas con aguas del distrito La Ramada, se realizaron muestreos cada 8 días, se midió el área foliar y el peso seco. Se estimaron los parámetros de crecimiento con el modelo logístico y con la ecuación ajustada mediante el software SAS. Empleando el enfoque funcional, se derivaron algunos índices de crecimiento: tasa relativa de crecimiento (TRC, índice de área foliar (IAF, tasa de asimilación neta (TAN, tasa de crecimiento del cultivo (TCC, área foliar específica (AFE y la relación de área foliar (RAF. La TRC máxima en los primeros 10 días después del trasplante (ddt fue de 0,1164 g g-1 día-1; IAF máximo a los 61 días: 6,78; la TAN a los 24 ddt alcanzó el máximo de 0,00046 g cm-2 día-1; la TCC presentó el máximo a los 35 ddt, con 0,0007 g cm-2 día-1; la AFE máxima fue de 497,55 cm2 g-1 al trasplante y la RAF alta al trasplante de 483,38 cm2 g-1. La salinidad presente en los suelos del Centro Agropecuario Marengo ocasionó una reducción en los parámetros de crecimiento en lechuga.

  14. Effect of Restricting Access to Health Care on Health Expenditures among Asylum-Seekers and Refugees: A Quasi-Experimental Study in Germany, 1994-2013.

    Directory of Open Access Journals (Sweden)

    Kayvan Bozorgmehr

    Full Text Available Access to health care for asylum-seekers and refugees (AS&R in Germany is initially restricted before regular access is granted, allegedly leading to delayed care and increasing costs of care. We analyse the effects of (a restricted access; and (b two major policy reforms (1997, 2007 on incident health expenditures for AS&R in 1994-2013.We used annual, nation-wide, aggregate data of the German Federal Statistics Office (1994-2013 to compare incident health expenditures among AS&R with restricted access (exposed to AS&R with regular access (unexposed. We calculated incidence rate differences (∆IRt and rate ratios (IRRt, as well as attributable fractions among the exposed (AFe and the total population (AFp. The effects of between-group differences in need, and of policy reforms, on differences in per capita expenditures were assessed in (segmented linear regression models. The exposed and unexposed groups comprised 4.16 and 1.53 million person-years. Per capita expenditures (1994-2013 were higher in the group with restricted access in absolute (∆IRt = 375.80 Euros [375.77; 375.89] and relative terms (IRR = 1.39. The AFe was 28.07% and the AFp 22.21%. Between-group differences in mean age and in the type of accommodation were the main independent predictors of between-group expenditure differences. Need variables explained 50-75% of the variation in between-group differences over time. The 1997 policy reform significantly increased ∆IRt adjusted for secular trends and between-group differences in age (by 600.0 Euros [212.6; 986.2] and sex (by 867.0 Euros [390.9; 1342.5]. The 2007 policy reform had no such effect.The cost of excluding AS&R from health care appears ultimately higher than granting regular access to care. Excess expenditures attributable to the restriction were substantial and could not be completely explained by differences in need. An evidence-informed discourse on access to health care for AS&R in Germany is needed; it

  15. Synthesis of nanoparticles of manganese MnFe2O4 by co-precipitation micellar ferrite: structural and magnetic properties

    International Nuclear Information System (INIS)

    Alvarez-Paneque, A.; Diaz, S.; Diaz, C.; Santiago-Jacinto, E.; Reguera, E.

    2008-01-01

    Full text: The microemulsion method was used in reverse, shaped micelles by dodecyl of sodium (NaDBS) in toluene/water system, for MnFe2O4 manganese ferrite magnetic nanoparticles. Were also variants of heat treatments to improve the crystallinity of the material obtained. These were, treatments to reflux to 100 ° C or treatments in an inert atmosphere at temperatures that were varied between 350 and 600 ° C. The retrieved material was characterized by x-ray diffraction (XRD), transmission electron microscopy of high and low resolution (HR-TEM and TEM, respectively), Mössbauer Spectroscopy and vibrational magnetometry. Powder XRD patterns revealed the formation of phase MnFe2O4, cubic type Spinel, of space group Fd3m, accompanied by the minority phase Hematite (a-Fe203) group spatial R-3 c. The size of the nanoparticles was estimated from the profile setting from the pattern of powder by the method of Le Bail, obtaining sizes mean that varied between 5 and 25 mn depending on the heat treatment to which they were subjected. This result was corroborated from TEM micrographs. The vibrational magnetometer showed that the smaller MnFe2O4 nanoparticles, prepared following this route of synthesis They presented a superparamagnetic behavior at room temperature (coercive field and) remanence approximately zeros), which was also confirmed by the study of Mössbauer Spectroscopy. Was also the magnetically inactive layer thickness, of around 0.9 nm, responsible for the decrease in the values of saturation magnetization (as) to decrease the size of nanoparticles. Was obtained a set of nanoparticles with superparamagnetic behavior based in the MnFe2O4 around 5.9 NM in diameter and a-Fe203 around 6.6 NM, as phase secondary. They managed to get this material and the desired magnetic properties optimum crystallinity, applying heat treatment variant proposed in this work, and that It consists of making a reflux at 100 ° C, before the treatment on solid phase under flow N2

  16. Social skills inventory for adolescents: evidence of construct validity and reliability = Inventário de habilidades sociais para adolescentes: evidências de validade de constructo e confiabilidade = Inventario de habilidades sociales para adolescentes: evidencia de validez de constructo y confiabilidad

    Directory of Open Access Journals (Sweden)

    Leme, Vanessa Barbosa Romera

    2016-01-01

    Full Text Available As habilidades sociais têm sido tomadas como um importante indicador de desenvolvimento social e emocional. Para avaliação desse repertório, tem-se, no contexto brasileiro, o Inventário de Habilidades Sociais para Adolescentes (IHSA-Del-Prette. Esse instrumento de medida é amplamente utilizado na investigação e intervenção, com propriedades psicométricas favoráveis obtidas por Análise de Componentes Principais (ACP. Este estudo visa comparar a estrutura obtida por ACP à obtida por Análise Fatorial Exploratória (AFE e verificar os indicadores de validade e confiabilidade produzidos por Análise Fatorial Confirmatória (AFC. Participaram 2291 estudantes do 6º, 7º e 8º ano do Ensino Fundamental e do 1º e 2º ano do Ensino Médio. Os resultados evidenciaram uma estrutura fatorial muito similar à originalmente produzida com a ACP, com seis fatores oblíquos confirmados pela AFC e com indicadores adequados de confiabilidade. Conclui-se que o IHSA-Del-Prette apresenta qualidades psicométricas que o recomendam para uso no contexto brasileiro

  17. [Measuring the positive dimensions among health care workers: a contribution to the Italian validation of the UWES--Utrecht Work Engagement Scale].

    Science.gov (United States)

    Pisanti, R; Paplomatas, A; Bertini, M

    2008-01-01

    Engagement is defined as a positive, fulfilling, work-related state of mind that is characterized by vigor, dedication, and absorption. The main purpose of this study was to examine the psychometric properties of the Utrecht Work Engagement Scale (UWES). Data from a sample of health care workers (N=948) were used to test four propositions concerning dimensionality, internal consistency and construct validity. The UWES Italian version and the Multidimensional Organizational Health Questionnaire (MOHQ) were administered to the subjects (a subsample of 225 health care workers also completed the Maslach Burnout Inventory). The factorial structure has been examined through a series of Explorative Factor Analysis (AFE) and Confirmatory Factor Analysis (CFA). As in the original version, we found a three factor solution. Internal consistency indexes were satisfactory. In addition, the correlations between UWES, MOHQ and MBI revealed a good construct validity. It is concluded that the Italian Version of the UWES has acceptable psychometric properties and that the instrument can be used in studies on positive organizational behavior.

  18. Design of a Modular Multilevel Converter as an Active Front-End for a magnet supply application

    CERN Document Server

    Panagiotis, Asimakopoulos; Massimo, Bongiorno

    2015-01-01

    The aim of this work is to describe the general design procedure of a Modular Multilevel Converter (MMC) applied as an Active Front-End (AFE) for a magnet supply for beam accelerators. The dimensioning criteria for the converter and the dc-link capacitance are presented and the grid transformer requirements are set. Considering the converter design, the arm inductance calculation is based on the specifications for the arm-current ripple and the DC-link fault tolerance, but, also, on the limitation of the second harmonic and the second-order LC resonance of the arm current. The module capacitance value is evaluated by focusing on the required switching dynamics and the capacitor-voltage ripple according to a newly proposed graphical method. The loading of each semiconductor in the half bridge is calculated via simulation, indicating the unsymmetrical current distribution. It is concluded that the current distribution for each semiconductor depends on the mode of operation of the converter. The different criter...

  19. Proteogenomic analysis reveals alternative splicing and translation as part of the abscisic acid response in Arabidopsis seedlings.

    Science.gov (United States)

    Zhu, Fu-Yuan; Chen, Mo-Xian; Ye, Neng-Hui; Shi, Lu; Ma, Kai-Long; Yang, Jing-Fang; Cao, Yun-Ying; Zhang, Youjun; Yoshida, Takuya; Fernie, Alisdair R; Fan, Guang-Yi; Wen, Bo; Zhou, Ruo; Liu, Tie-Yuan; Fan, Tao; Gao, Bei; Zhang, Di; Hao, Ge-Fei; Xiao, Shi; Liu, Ying-Gao; Zhang, Jianhua

    2017-08-01

    In eukaryotes, mechanisms such as alternative splicing (AS) and alternative translation initiation (ATI) contribute to organismal protein diversity. Specifically, splicing factors play crucial roles in responses to environment and development cues; however, the underlying mechanisms are not well investigated in plants. Here, we report the parallel employment of short-read RNA sequencing, single molecule long-read sequencing and proteomic identification to unravel AS isoforms and previously unannotated proteins in response to abscisic acid (ABA) treatment. Combining the data from the two sequencing methods, approximately 83.4% of intron-containing genes were alternatively spliced. Two AS types, which are referred to as alternative first exon (AFE) and alternative last exon (ALE), were more abundant than intron retention (IR); however, by contrast to AS events detected under normal conditions, differentially expressed AS isoforms were more likely to be translated. ABA extensively affects the AS pattern, indicated by the increasing number of non-conventional splicing sites. This work also identified thousands of unannotated peptides and proteins by ATI based on mass spectrometry and a virtual peptide library deduced from both strands of coding regions within the Arabidopsis genome. The results enhance our understanding of AS and alternative translation mechanisms under normal conditions, and in response to ABA treatment. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  20. Object-oriented philosophy in designing adaptive finite-element package for 3D elliptic deferential equations

    Science.gov (United States)

    Zhengyong, R.; Jingtian, T.; Changsheng, L.; Xiao, X.

    2007-12-01

    Although adaptive finite-element (AFE) analysis is becoming more and more focused in scientific and engineering fields, its efficient implementations are remain to be a discussed problem as its more complex procedures. In this paper, we propose a clear C++ framework implementation to show the powerful properties of Object-oriented philosophy (OOP) in designing such complex adaptive procedure. In terms of the modal functions of OOP language, the whole adaptive system is divided into several separate parts such as the mesh generation or refinement, a-posterior error estimator, adaptive strategy and the final post processing. After proper designs are locally performed on these separate modals, a connected framework of adaptive procedure is formed finally. Based on the general elliptic deferential equation, little efforts should be added in the adaptive framework to do practical simulations. To show the preferable properties of OOP adaptive designing, two numerical examples are tested. The first one is the 3D direct current resistivity problem in which the powerful framework is efficiently shown as only little divisions are added. And then, in the second induced polarization£¨IP£©exploration case, new adaptive procedure is easily added which adequately shows the strong extendibility and re-usage of OOP language. Finally we believe based on the modal framework adaptive implementation by OOP methodology, more advanced adaptive analysis system will be available in future.

  1. Design of area array CCD image acquisition and display system based on FPGA

    Science.gov (United States)

    Li, Lei; Zhang, Ning; Li, Tianting; Pan, Yue; Dai, Yuming

    2014-09-01

    With the development of science and technology, CCD(Charge-coupled Device) has been widely applied in various fields and plays an important role in the modern sensing system, therefore researching a real-time image acquisition and display plan based on CCD device has great significance. This paper introduces an image data acquisition and display system of area array CCD based on FPGA. Several key technical challenges and problems of the system have also been analyzed and followed solutions put forward .The FPGA works as the core processing unit in the system that controls the integral time sequence .The ICX285AL area array CCD image sensor produced by SONY Corporation has been used in the system. The FPGA works to complete the driver of the area array CCD, then analog front end (AFE) processes the signal of the CCD image, including amplification, filtering, noise elimination, CDS correlation double sampling, etc. AD9945 produced by ADI Corporation to convert analog signal to digital signal. Developed Camera Link high-speed data transmission circuit, and completed the PC-end software design of the image acquisition, and realized the real-time display of images. The result through practical testing indicates that the system in the image acquisition and control is stable and reliable, and the indicators meet the actual project requirements.

  2. Physician use of updated anti-virus software in a tertiary Nigerian hospital.

    Science.gov (United States)

    Laabes, E P; Nyango, D D; Ayedima, M M; Ladep, N G

    2010-01-01

    While physicians are becoming increasingly dependent on computers and the internet, highly lethal malware continue to be loaded into cyberspace. We sought to assess the proportion of physicians with updated anti-virus software in Jos University Teaching Hospital Nigeria and to determine perceived barriers to getting updates. We used a pre-tested semi-structured self-administered questionnaire to conduct a cross-sectional survey among 118 physicians. The mean age (+/- SD) of subjects was 34 (+/- 4) years, with 94 male and 24 female physicians. Forty-two (36.5%) of 115 physicians with anti-virus software used an updated program (95% Cl: 27, 45). The top-three antivirus software were: McAfee 40 (33.9%), AVG 37 (31.4%) and Norton 17 (14.4%). Common infections were: Trojan horse 22 (29.7%), Brontok worm 8 (10.8%), and Ravmonlog.exe 5 (6.8%). Internet browsing with a firewall was an independent determinant for use of updated anti-virus software [OR 4.3, 95% CI, 1.86, 10.02; P malware producers and anti-virus software developers.

  3. Crystal growth and characterization of SrFe{sub 2}(As{sub 1-x}P{sub x}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Baglatzi, Fryni; Adamski, Agnes; Krellner, Cornelius [Physikalisches Institut, Goethe Universitaet Frankfurt am Main, D-60438, Frankfurt am Main (Germany)

    2016-07-01

    The discovery of iron-based superconductors brought new excitement to the field of unconventional superconducting (SC). Most studied are the so called (122 compounds), the AFe{sub 2}As{sub 2} with A=Ba, Sr or Ca. An important point is, that different substitution series reveal different temperature-concentration phase diagrams, including varying SC order parameters and coexistence regions of magnetism and SC. The crystal growth of SrFe{sub 2}As{sub 2} can be achieved by using the self-flux technique. However, exact melting temperatures of various flux to composition ratios are not reported in literature. We determined the melting points for various flux concentrations, using differential thermal analysis (DTA) in order to find out the pseudo binary phase diagram. Furthermore, crystal growth was conducted on the phosphorous doped series. Our samples were analyzed with scanning electron microscope, energy dispersive x-ray analysis and powder diffractometry, in order to determine the phase relations and distribution coefficients.

  4. Sedimentary paleoenvironments of the Candeleros Formation(Rio Limay Subgroup)upper cretaceous, Ezequiel Ramos Mexia, Neuquen, Argentina daming west, Argentina

    International Nuclear Information System (INIS)

    Sanchez, M.

    2004-01-01

    Sedimentary facies from the Candeleros Formation (Rio Limay Subgroup), cropping out at the El Escondido creek, at the Ezequiel Ramos Mexia dam, are analyzed and interpreted in this paper. A sedimentological detailed section was measured to get the main goal of this paper which is the sedimentary paleoenvironment. The outcroppings were pictured and a section was measured, geometries and espacial relation between them were analyzed. Eight lithofacies were identified which are: coarse sandstone facies (Se), sandstones (Sm, St, Sp, Sh t Sr), siltstones and shales (Fl and Fr). These lithofacies were agrupated into eight facies associations (FA). AFA constitutes the registration of multiepisodic events of sheet floods; AFB, C and D are product of the depositation in a braided channel belt, AFE represents units of lateral accretion, AFF is assigned deposits of crevasse splay and AFG and H are assigned to plain of flood. The distribution of these associations in the column defines an terminal fan paleoenvironment where is represented of base to top: distal (AFA, B and G) and proximal area (AFD and G) of the distributary plain; zone of feeding of the system (AFC, And, F and G), media-proximal distributary plain (AFD and F), proximal distributary plain (AFC, And, F and G); and flood basin (AFF, G and H) [es

  5. Visible-light photochemical activity of heterostructured core-shell materials composed of selected ternary titanates and ferrites coated by tiO2.

    Science.gov (United States)

    Li, Li; Liu, Xuan; Zhang, Yiling; Nuhfer, Noel T; Barmak, Katayun; Salvador, Paul A; Rohrer, Gregory S

    2013-06-12

    Heterostructured photocatalysts comprised of microcrystalline (mc-) cores and nanostructured (ns-) shells were prepared by the sol-gel method. The ability of titania-coated ATiO3 (A = Fe, Pb) and AFeO3 (A = Bi, La, Y) catalysts to degrade methylene blue in visible light (λ > 420 nm) was compared. The catalysts with the titanate cores had enhanced photocatalytic activities for methylene blue degradation compared to their components alone, whereas the catalysts with ferrite cores did not. The temperature at which the ns-titania shell is crystallized influences the photocatalytic dye degradation. mc-FeTiO3/ns-TiO2 annealed at 500 °C shows the highest reaction rate. Fe-doped TiO2, which absorbs visible light, did not show enhanced photocatalytic activity for methylene blue degradation. This result indicates that iron contamination is not a decisive factor in the reduced reactivity of the titania coated ferrite catalysts. The higher reactivity of materials with the titanate cores suggests that photogenerated charge carriers are more easily transported across the titanate-titanate interface than the ferrite-titanate interface and this provides guidance for materials selection in composite catalyst design.

  6. Validación de constructo de un Cuestionario de Evaluación de la Competencia Docente

    Directory of Open Access Journals (Sweden)

    Edna Luna Serrano

    2015-08-01

    Full Text Available Este trabajo analiza la estructura interna del Cuestionario de Evaluación de la Competencia Docente, producto de un riguroso proceso metodológico de acumulación de evidencias de validez y confiabilidad. El cuestionario se fundamenta en el Modelo de Evaluación de Competencias Docentes (MECD. Se replicaron los análisis de unidimensionalidad (n=128,791 y AFE (n=67,111, como resultado se demostró que 32 reactivos evalúan el mismo constructo, la estructura interna reveló dos factores: planeación y gestión del proceso enseñanza-aprendizaje y conducción y valoración del proceso enseñanza-aprendizaje; una varianza total de 75.02% y alpha de Cronbach de .98. La estructura se comprobó con modelamiento de ecuaciones estructurales (n=462, donde resultó un RMSEA=.07, SRMR=.02, CFI y TLI=93. Se concluye que el cuestionario integra los componentes de la competencia docente significativos para los estudiantes y se demuestra su representatividad con las dimensiones del MECD.

  7. Rural Alaska Coal Bed Methane: Application of New Technologies to Explore and Produce Energy

    Energy Technology Data Exchange (ETDEWEB)

    David O. Ogbe; Shirish L. Patil; Doug Reynolds

    2005-06-30

    The Petroleum Development Laboratory, University of Alaska Fairbanks prepared this report. The US Department of Energy NETL sponsored this project through the Arctic Energy Technology Development Laboratory (AETDL) of the University of Alaska Fairbanks. The financial support of the AETDL is gratefully acknowledged. We also acknowledge the co-operation from the other investigators, including James G. Clough of the State of Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys; Art Clark, Charles Barker and Ed Weeks of the USGS; Beth Mclean and Robert Fisk of the Bureau of Land Management. James Ferguson and David Ogbe carried out the pre-drilling economic analysis, and Doug Reynolds conducted post drilling economic analysis. We also acknowledge the support received from Eric Opstad of Elko International, LLC; Anchorage, Alaska who provided a comprehensive AFE (Authorization for Expenditure) for pilot well drilling and completion at Fort Yukon. This report was prepared by David Ogbe, Shirish Patil, Doug Reynolds, and Santanu Khataniar of the University of Alaska Fairbanks, and James Clough of the Alaska Division of Geological and Geophysical Survey. The following research assistants, Kanhaiyalal Patel, Amy Rodman, and Michael Olaniran worked on this project.

  8. The self-determination theory applied in the analysis of motivation and academic performance of accounting students in a brazilian public university

    Directory of Open Access Journals (Sweden)

    Marina Salgado Borges

    2017-08-01

    Full Text Available The aim of this study was analyzing the relations between academic performance and motivation of Accounting students in a Brazilian public university based on Self-determination Theory. Methodologically, in order to reach that, structured questionnaires were applied in classrooms with the Brazilian version of the Academic Motivation Scale (AMS, in a sample of 316 students enrolled from second to tenth periods of that course, equivalent to 37.2% of the total number of students. Data were analyzed using descriptive statistics, exploratory factor analysis (AFE and multiple linear regression analysis with Ordinary Least Squares (OLS. The regression analyzes indicated a significant relationship between motivation and academic performance. The factors related to intrinsic motivation and extrinsic motivation by identified regulation are positively correlated with academic performance of students. On the other hand, the introjected for regulation extrinsic motivation factor is negatively correlated with student’s academic performance coefficient (CRA. Based on the sample analyzed, the results showed that the relationship between motivation and CRA of the student depends on the type of motivation that is present in each one.

  9. The use of NTA for lead phytoextraction from soil from a battery recycling site.

    Science.gov (United States)

    Freitas, Eriberto Vagner de Souza; do Nascimento, Clístenes Williams Araújo

    2009-11-15

    The application of synthetic aminopolycarboxylic acids to soil increases metal solubility, and therefore enhances phytoextraction. However, synthetic chelants degrade poorly in soil, and metal leaching threatens human and animal health. The aim of this study is to assess the use of a biodegradable chelant (NTA) for Pb phytoextraction from a soil contaminated by battery-casing disposal. EDTA was also included in the experiment to assess the behavior of a non-degradable chelant. Each synthetic chelant was applied to soil pots cultivated with maize plants at rates of 0, 2, 5, 10, and 20 mmol kg(-1). Soil samples were extracted with CaCl(2) and by sequential extraction for Pb. In addition, a soil column experiment was set up to study the leaching of Pb from the chelant-amended soil. The results showed that both NTA and EDTA were highly effective in solubilizing Pb from soil. The Pb distribution into soil fractions after chelant addition followed the sequence: Ex (exchangeable)>OM (organic matter)>AFeOx (amorphous iron oxides)>CFeOx (crystalline iron oxides). The 5 mmol kg(-1) dose of EDTA increased the Pb concentration in maize shoots to 1.1%, but it promoted unacceptable Pb leaching rates. On the other hand, the results showed that phytoremediating the site using 5 mmol kg(-1) NTA could be feasible with no environmental effects due to Pb leaching over a five-year period.

  10. Using Cable Suspended Submersible Pumps to Reduce Production Costs to Increase Ultimate Recovery in the Red Mountain Field of the San Juan Basin Region

    Energy Technology Data Exchange (ETDEWEB)

    Don L. Hanosh

    2006-08-15

    A joint venture between Enerdyne LLC, a small independent oil and gas producer, and Pumping Solutions Inc., developer of a low volume electric submersible pump, suspended from a cable, both based in Albuquerque, New Mexico, has re-established marginal oil production from Red Mountain Oil Field, located in the San Juan Basin, New Mexico by working over 17 existing wells, installing cable suspended submersible pumps ( Phase I ) and operating the oil field for approximately one year ( Phase II ). Upon the completion of Phases I and II ( Budget Period I ), Enerdyne LLC commenced work on Phase III which required additional drilling in an attempt to improve field economics ( Budget Period II ). The project was funded through a cooperative 50% cost sharing agreement between Enerdyne LLC and the National Energy Technology Laboratory (NETL), United States Department of Energy, executed on April 16, 2003. The total estimated cost for the two Budget Periods, of the Agreement, was $1,205,008.00 as detailed in Phase I, II & III Authorization for Expenditures (AFE). This report describes tasks performed and results experienced by Enerdyne LLC during the three phases of the cooperative agreement.

  11. Application software profiles 2010

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-04-15

    This article presented information on new software applications designed to facilitate petroleum exploration, drilling and production activities. Computer modelling and analysis enables oil and gas producers to characterize reservoirs, estimate reserves forecast production, plan operations and manage assets. Seven Calgary-based organizations were highlighted along with their sophisticated software tools, the applications and the new features available in each product. The geoSCOUT version 7.7 by GeoLOGIC Systems Ltd. integrates public and proprietary data on wells, well logs, reserves, pipelines, production, ownership and seismic location data. The Value Navigator and AFE Navigator by Energy Navigator provides control over reserves, production and cash flow forecasting. FAST Harmony, FAST Evolution, FAST CBM, FAST FieldNotes, Fast Piper, FAST RTA, FAST VirtuWell and FAST WellTest by Fekete Associates Inc. provide reserve evaluations for reservoir engineering projects and production data analysis. The esi.manage software program by 3esi improves business results for upstream oil and gas companies through enhanced decision making and workforce effectiveness. WELLFLO, PIPEFLO, FORGAS, OLGA, Drillbench, and MEPO wellbore solutions by Neotec provide unique platforms for flow simulation to optimize oil and gas production systems. Petrel, ECLIPSE, Avocet, PipeSim and Merak software tools by Schlumberger Information Solutions are petroleum systems modelling tools for geologic mapping, visualization modelling and reservoir engineering. StudioSL by Streamsim Technologies Inc. is a modelling tool for optimizing flood management. figs.

  12. [Analysis of the results of total cervical disc arthroplasty using a M6-C prosthesis: a multicenter study].

    Science.gov (United States)

    Byval'tsev, V A; Kalinin, A A; Stepanov, I A; Pestryakov, Yu Ya; Shepelev, V V

    Cervical spondylosis and intervertebral disc (IVD) degeneration are the most common cause for compression of the spinal cord and/or its roots. Total IVD arthroplasty, as a modern alternative to surgical treatment of IVD degeneration, is gaining popularity in many neurosurgical clinics around the world. Aim - the study aim was to conduct a multicenter analysis of cervical spine arthroplasty with an IVD prosthesis M6-C ('Spinal Kinetics', USA). The study included 112 patients (77 males and 35 females). All patients underwent single-level discectomy with implantation of the artificial IVD prosthesis M6-C. The follow-up period was up to 36 months. Dynamic assessment of the prosthesis was based on clinical parameters (pain intensity in the cervical spine and upper extremities (visual analog scale - VAS); quality of life (Neck Disability Index - NDI)); and subjective satisfaction with the results of surgical treatment (Macnab scale) and instrumental data (range of motion in the operated spinal motion segment, degree of heterotopic ossification (McAfee-Suchomel classification), and time course of degenerative changes in the adjacent segments).

  13. Transparent Fingerprint Sensor System for Large Flat Panel Display

    Directory of Open Access Journals (Sweden)

    Wonkuk Seo

    2018-01-01

    Full Text Available In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO TFT sensor array and associated custom Read-Out IC (ROIC are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC. To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger’s ridges and valleys through the fingerprint sensor array.

  14. Transparent Fingerprint Sensor System for Large Flat Panel Display.

    Science.gov (United States)

    Seo, Wonkuk; Pi, Jae-Eun; Cho, Sung Haeung; Kang, Seung-Youl; Ahn, Seong-Deok; Hwang, Chi-Sun; Jeon, Ho-Sik; Kim, Jong-Uk; Lee, Myunghee

    2018-01-19

    In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT) sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO) TFT sensor array and associated custom Read-Out IC (ROIC) are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE) amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC). To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger's ridges and valleys through the fingerprint sensor array.

  15. Electrochemical behaviour of stainless steel under radiation and exposed to representative chemistry in pressurised water reactor conditions

    International Nuclear Information System (INIS)

    Wang, Mi

    2013-01-01

    The dissertation focuses on the behaviour of stainless steel under irradiation and exposed to primary PWR conditions. The electrochemical potential of austenitic 316L stainless steel and the environmental parameters (hydrogen pressure, temperature, etc.,) have been measured continuously at high temperature (HT) and high pressure (HP) under irradiation, using a unique experimental HTHP working cell. Two sources of irradiation, proton and electron beams, have been employed in the study. A high similarity of electrochemical behaviour under both types of irradiations has been observed: (i) an oxidative potential response under irradiation (few tens of milli-volts); (ii) an increase in the hydrogen pressure reduces the oxidative potential response; (iii) a synergetic effect of thermal ageing and fluence leading to a decrease of the oxidative response under irradiation. The observations of the oxide film showed that without irradiation, metallic nickel in the inner and outer oxide films has been observed under a high hydrogen pressure. Under irradiation, um scale cavities (pits) have been observed in the strongly electron irradiated oxide film formed on 316L stainless steel. These defects are induced by the effect of irradiation of the passive film and water radiolysis. It is also shown that water radiolysis influences the PWR water chemistry by making it become a stronger oxidant at the oxide/solution interface. As a result, the release of metallic cations is increased and a-Fe 2 O 3 hematite has been observed on the irradiated outer oxide film where cavities were formed. (author) [fr

  16. Comparación de los modelos formativo, reflexivo y de antecedentes de evaluación estudiantil del servicio de docencia || Comparison of Formative, Reflective, and Antecedents Models of Students Evaluation of Teaching Service

    Directory of Open Access Journals (Sweden)

    Valdivieso Taborga, Carlos Eduardo

    2013-01-01

    Full Text Available Se ha llevado a cabo un análisis comparativo entre un modelo con enfoque de medición formativo, otro reflexivo y un tercero de antecedentes, de las dimensiones de la calidad de servicio de docencia. Previamente se diseñaron instrumentos válidos y fiables para la medición de la calidad de servicio y sus constructos relacionados, a través de un estudio exploratorio para obtener validez de contenido. Además, se llevaron a cabo un análisis factorial exploratorio (AFE y otro confirmatorio (AFC, para obtener la estructura dimensional adecuada e ítems relevantes. Usando modelos de estructuras de covarianza (MEC se comprobó que el modelo de antecedentes, aunque presenta igual poder predictivo, tiene mejores índices de ajuste que los modelos reflexivo y formativo. || A comparative analysis between three measurement models (with formative, reflective, and antecedents approach has been conducted to measure the dimensions of the teaching service quality. Previously valid and reliable instruments have been designed to measure the service quality and related constructs. An exploratory study has been performed to obtain content validity. Additionally, both exploratory and confirmatory factor analysis (EFA and CFA, respectively have been conducted to obtain the appropriate dimensional structure and relevant items. Using structural equations modeling (MEC has been found that the antecedent model, although it has the same predictive power, has better fit indices than reflective and formative models.

  17. Probing size-dependent electrokinetics of hematite aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Kedra-Królik, Karolina; Rosso, Kevin M.; Zarzycki, Piotr

    2017-02-01

    Aqueous particle suspensions of many kinds are stabilized by the electrostatic potential developed at their surfaces from reaction with water and ions. An important and less well understood aspect of this stabilization is the dependence of the electrostatic surface potential on particle size. Surface electrostatics are typically probed by measuring particle electrophoretic mobilities and quantified in the electrokinetic potential (f), using commercially available Zeta Potential Analyzers (ZPA). Even though ZPAs provide frequency-spectra (histograms) of electrophoretic mobility and hydrodynamic diameter, typically only the maximal-intensity values are reported, despite the information in the remainder of the spectra. Here we propose a mapping procedure that inter-correlates these histograms to extract additional insight, in this case to probe particle size-dependent electrokinetics. Our method is illustrated for a suspension of prototypical iron (III) oxide (hematite, a-Fe2O3). We found that the electrophoretic mobility and f-potential are a linear function of the aggregate size. By analyzing the distribution of surface site types as a function of aggregate size we show that site coordination increases with increasing aggregate diameter. This observation explains why the acidity of the iron oxide particles decreases with increasing particle size.

  18. A Molecular dynamics study of helium bubble stability during high-energy displacement cascades in alpha-iron

    International Nuclear Information System (INIS)

    Pu, Jin; Yang, Li; Zu, Xiaotao; Gao, Fei

    2007-01-01

    The interactions of high-energy displacement cascades with helium bubbles in a-Fe are investigated using molecular dynamics simulations. Initial bubbles with the volumes of 212 and 636 (angstrom)3 are considered, and the helium-to-vacancy (He/V) ratio in the bubbles varies from 0.5 to 3. Primary knock-on atom (PKA) energy, Ep, is up to 40 keV. The results show that the change of nm-sized He bubbles due to displacement cascade does not depend much on the bubble size, but rather on the He/V ratio and the recoil energy. For the initial He/V ratio less than 1, the size of the bubbles decreases with increasing PKA energy, but the He/V ratio increases. However, for the initial He/V ratio of 3, the size of the bubbles increases, and the He/V ratio decreases with PKA energy. For the initial He/V ratio of 1, the ratio of the small bubble decreases slightly, but the ratio of the large bubble remains unchanged for lower PKA energy, and increases slightly for higher PKA energy. The reasons for these observed phenomena have been explained

  19. Determination of the solubility limiting solid of the selenium in the presence of iron under anoxic conditions

    International Nuclear Information System (INIS)

    Iida, Y.; Yamaguchi, T.; Tanaka, T.; Kitamura, A.; Nakayama, S.

    2009-01-01

    Dissolution experiments of selenium were performed from both under saturation and over saturation directions to determine the solubility limiting solid of selenium under the conditions which thermodynamically prefer the formation of ferroselite (FeSe 2 ). X-ray diffractometry (XRD) showed that FeSe 2 was formed in the over-saturation experiments. However, the ion activity products for the reaction of 0.5 FeSe 2 + H + + e - 0.5 Fe 2+ + HSe - , aFe 2+0.5 aHSe - a H+ -1 a e- -1 , obtained from both under saturation and over saturation directions were 3 to 4 orders of magnitude higher than the equilibrium constants calculated from existing thermodynamic data. The dependencies of the selenium concentration on pH, Eh and the iron concentration were better interpreted as a dissolution reaction of selenium solid (Se(s)) than the iron-selenium compounds. The equilibrium constant of: Se(s) + H + + 2e - = HSe - was determined to be logK 0 -7.46±0.11. This value agrees with the value of logK 0 = -7.62±0.06 calculated from existing thermodynamic data of crystalline selenium within errors. Because crystalline selenium was not identified in the solid phases by XRD, the solubility limiting solid would be amorphous or minor amount of crystalline selenium, even if the iron-selenium compound was formed. (authors)

  20. Valence electron structure and bonding features of RuB2 and OSB2: The empirical electron theory calculations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The valence electron structure (VES) of RuB2 and OsB2 were calculated by the empirical electron theory (EET) of solids and molecules and compared with the results derived from the first-principles calculations. The distributions of covalent electrons in different bonds indicate that B-B and B-Me have remarkably covalent bonding characters. Lattice electrons cruising around Me-Me layers are found to have great influences on electronic conductivity and high temperature plasticity. The ultra-high values of elastic constant Cn in the two compounds originate from close-packed covalent bonding along the c axis. Uneven bond strengths and distributions of covalent bonds, especially for B-Afe bonds, yield significant anisotropy. Low ratios of lattice electrons to covalent electrons suggest the intrinsic embrittlement in crystals. The fact that the calculated cohesive energies well agree with experimental results demonstrates the good suitability of the EET calculations in estimating cohesive energy for transition-metal borides.

  1. Indium-111 oxine labelling of white blood cells

    International Nuclear Information System (INIS)

    Lavender, J.P.; Silvester, D.J.; Goldman, J.; Hammersmith Hospital, London

    1978-01-01

    Following work done by Professor John McAfee and Mathew Thakur at the MRS Cyclotron Unit a method is available for labelling cells with indium-111 which results in a stable intracellular marker. The method uses indium-111-8 hydroxyquinoline (111In oxine) which is a lipoid soluble complex which goes across the cell membrane and results in the deposition of indium into various subcellular structures. It has been applied to various preparations of white cells, platelets and also malignant cells. Autologous granulocytes have been used to identify inflammatory lesions in 35 patients. By similar means autologous lymphocytes can also be labelled and reinfused. Lymphocytes have been shown in animals to circulate from the blood via the lymphatic system and then returning to the blood once more. The same phenomenon can be seen in man using indium labelled lymphocytes. Lymph nodes become visible at between 12 and 18 hours and recirculation of labelled cells can be shown on the blood activity curves. Certain problems arise concerning cell behaviour after labelling which appear due to irradiation of cells rather than chemical toxicity. (author)

  2. Theory of two-magnon Raman scattering in alkaline iron selenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.S. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Zhang, A.M. [Department of Physics, Renmin University of China, Beijing 100872 (China); Xu, T.F. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Wu, W.C., E-mail: wu@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

    2014-11-15

    Highlights: • Two-magnon Raman scattering is theoretically studied for alkaline iron selenides. • Underlying spin interactions of the √(5)×√(5) AF superstructure are investigated in details. • Optimal set of exchange parameters is revealed when fitting to experiments. - Abstract: Motivated by the recent experiment of two-magnon Raman scattering in alkaline iron selenide superconductors (Zhang et al., 2012), we investigate in details the underlying spin interactions of the √(5)×√(5) antiferromagnetic superstructure. Based on the linear spin wave approximation, the Fleury-London (FL) two-magnon Raman cross-sections are calculated. By comparing theoretical results with the Raman data in both A{sub g} and B{sub g} channels, an optimal set of exchange parameters which are consistent with the fitting to the neutron scattering data are obtained. It reveals that the experimentally observed broad and asymmetric peaks around 1600 cm{sup −1} are dominantly originated from quasiparticle excitations in two nearly degenerate magnon bands in the (0,±π) and (±π,0) directions. The result thus supports that the magnetic properties in alkaline iron selenide AFe{sub 1.6+x}Se{sub 6} superconductors can be basically described by the quantum spin model with up to third nearest-neighbor exchange couplings.

  3. Desarrollo y validación de la Escala de Expectativas de Futuro en la Adolescencia (EEFA

    Directory of Open Access Journals (Sweden)

    Yolanda Sánchez-Sandoval

    Full Text Available El objetivo de este estudio es diseñar y validar el instrumento Escala de Expectativas de Futuro en la Adolescencia (EEFA. Se analizó una muestra compuesta por 1125 participantes de ambos sexos procedentes de la provincia de Cádiz, con edades comprendidas entre los 11 y 15 años. A partir del Análisis Factorial Exploratorio (AFE, realizado con la submuestra 1 (n=551, se identificaron cuatro factores: Expectativas económico/ laborales, Expectativas académicas, Expectativas de bienestar personal y Expectativas familiares. Mediante un Análisis Factorial Confirmatorio (AFC, usando la submuestra 2 (n=574, se confirmó la estructura factorial de la escala, cuyo modelo presentaba un buen ajuste. Los análisis de los ítems y de fiabilidad demostraron una aceptable consistencia interna de la escala. Para la obtención de otras evidencias de validez, los datos obtenidos mediante el instrumento EEFA se contrastaron con otros instrumentos que evalúan autoestima y satisfacción vital, esperando obtener relaciones positivas entre los mismos. Se concluye que el instrumento EEFA, compuesto por 14 ítems, posee propiedades psicométricas adecuadas, considerándose un instrumento válido para evaluar las expectativas de futuro que presentan los adolescentes.

  4. DATA ACQUISITION FOR SNS BEAM LOSS MONITOR SYSTEM

    International Nuclear Information System (INIS)

    YENG, Y.; GASSNER, D.; HOFF, L.; WITKOVER, R.

    2003-01-01

    The Spallation Neutron Source (SNS) beam loss monitor system uses VME based electronics to measure the radiation produced by lost beam. Beam loss signals from cylindrical argon-filled ion chambers and neutron detectors will be conditioned in analog front-end (AFE) circuitry. These signals will be digitized and further processed in a dedicated VME crate. Fast beam inhibit and low-level, long-term loss warnings will be generated to provide machine protection. The fast loss data will have a bandwidth of 35kHz. While the low level, long-term loss data will have much higher sensitivity. This is further complicated by the 3 decade range of intensity as the Ring accumulates beam. Therefore a bandwidth of 100kHz and dynamic range larger than 21 bits data acquisition system will be required for this purpose. Based on the evaluation of several commercial ADC modules in preliminary design phase, a 24 bits Sigma-Delta data acquisition VME bus card was chosen as the SNS BLM digitizer. An associated vxworks driver and EPICS device support module also have been developed at BNL. Simulating test results showed this system is fully qualified for both fast loss and low-level, long-term loss application. The first prototype including data acquisition hardware setup and EPICS software (running database and OPI clients) will be used in SNS Drift Tube Linac (DTL) system commissioning

  5. An X-ray absorption spectroscopic study of the metal site preference in Al1-xGaxFeO3

    Science.gov (United States)

    Walker, James D. S.; Grosvenor, Andrew P.

    2013-01-01

    Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO3 (Pna21; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al1-xGaxFeO3 was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L2,3-, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al1-xGaxFeO3 indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO3 than in GaFeO3, implying more anti-site disorder is present in AlFeO3.

  6. Requerimiento Hídrico de Gmelina arborea en Etapa de Vivero Bajo Condiciones Controladas

    Directory of Open Access Journals (Sweden)

    Amir Vergara

    2017-04-01

    Full Text Available RESUMEN Con el fin de conocer el requerimiento hídrico de Melina en la etapa de vivero, se realizó un ensayo con cuatro coeficientes de consumo (Kc: 0,6, 0,8, 1,2, 1,4. Estos tratamientos se transformaron en láminas de riego de 2,4 mm.día–1, 3,2 mm.día–1, 4,8 mm.día–1 y 5,6 mm.día–1 respectivamente, debido a que la evapotranspiración de referencia (ETO de la zona fue de 4 mm.día–1. Se observó que a medida que se aumentaba la lámina de riego, disminuía el crecimiento de las plantas. Los valores más altos de altura de planta, área foliar, masa seca de hoja, masa seca del tallo y masa seca de raíz se obtuvieron con la lámina de 2,4 mm.día–1. Por otro lado, los índices de crecimiento (TAC, TRC, AFE, RAF muestran la misma tendencia. Con base en estos resultados se determinó que el Kc para esta especie en la etapa de vivero es de 0,6.

  7. Adsorption/membrane filtration as a contaminant concentration and separation process for mixed wastes and tank wastes. 1998 annual progress report

    International Nuclear Information System (INIS)

    Benjamin, M.M.; Korshin, G.

    1998-01-01

    'This report describes progress through May, 1998, which is a little past mid-way through the second year of a three-year project. The goal of the research is to develop a treatment system for the separation of contaminants in low-organic Hanford tank wastes into various sub-groups that are relatively easy to treat further to yield products that are amenable to final disposal. The main target contaminants are Sr and Cs, although heavy metals and actinide-group elements are also targets. Effort during the first half-year of the project was devoted primarily to development of experimental and analytical techniques that could be used to test and quantify the treatability of Sr and Cs in the extremely complex matrix of the tank wastes. The treatment technologies to be tested for isolation of Sr from other waste constituents included adsorption of Sr onto various mineral solids and membrane separation of particulate from dissolved Sr. The proposed technology for treating Cs was electrochemically controlled, reversible binding of the Cs to hexacyanoferrates. Results obtained during the remainder of the first year suggested that hematite (a-Fe 2 O 3 ) and iron-oxide-coated sand (IOCS) were the best adsorbents for Sr among the oxides tested, and work during the second project year followed up on that result.'

  8. Tuning ZrFe{sub 4}Si{sub 2} by Ge and Y substitution

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Katharina [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Institute of Solid State Physics, TU Dresden (Germany); Mufti, Nandang; Bergmann, Christoph; Rosner, Helge; Geibel, Christoph [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Goltz, Til; Klauss, Hans-Henning [Institute of Solid State Physics, TU Dresden (Germany); Woike, Theo [Institute for Structural Physics, TU Dresden (Germany)

    2016-07-01

    The intermetallic compound series AFe{sub 4}X{sub 2} (A = Y, Lu, Zr; X = Si, Ge) presents a rare case of magnetic frustrated metallic systems. In particular ZrFe{sub 4}Si{sub 2} is of strong interest because our results indicate this system to be very close to a quantum critical point (QCP) where Fe magnetic order disappears. To get a deeper insight into its ground state, we performed a detailed study of Ge and Y substituted ZrFe{sub 4}Si{sub 2}. The isovalent substitution of Ge for Si induces a negative chemical pressure as Ge is larger than Si. As expected from this, the substitution results in the formation of a well-defined antiferromagnetic order with Neel temperatures increasing up to 25 K at 40 % Ge. This confirms ZrFe{sub 4}Si{sub 2} to be extremely close to the QCP, just on the magnetic side of it. With the second substitution series Y{sub x}Zr{sub 1-x}Fe{sub 4}Si{sub 2} we investigate the development from the highly reduced antiferromagnetic order in ZrFe{sub 4}Si{sub 2} towards the two magnetic transitions at 56 K and 76 K, which we see in YFe{sub 4}Si{sub 2}.

  9. Crescimento de crambe na presença ou ausência de competição interespecífica

    Directory of Open Access Journals (Sweden)

    Germani Concenço

    2015-10-01

    Full Text Available RESUMOCrambe (Crambe abyssinica has a cropping cycle of around 90 days, being suitable as an alternative to the second grain crop planted after soybean is harvested in the Center West region of Brazil. It is necessary to understand the growth and development dynamics of crambe plants in order to allow correct management of the production factors. This study aimed to describe the growth and development parameters of crambe plants under presence or absence of interspecific competition. The experiment was installed in the fall-winter 2011 in an Oxisoil, in completely randomized blocks design with three replications. Treatments comprised crambe plants growing either in presence or absence of interspecific simulated competition, throughout the cropping cycle. Plants were collected for the growth analysis every 15 days from harvest until 75 days after emergence. Growth parameters leaf area (AF, dry mass of stems/culms (MSC, leaves (MSF and total (MST dry mass, leaf area index (IAF, absolute (TCA and relative (TCR growth rates, net assimilation rate (TAL, specific leaf area (AFE, leaf area duration (DAF, leaf area ratio (RAF and leaf mass ratio (RMF were determined for the crop plants, subjected or not to competition, as well as for the simulated competitor. Crambe is a low competitive crop, being the competition more severe until 60-70 days after emergence. Besides, crop performance under field conditions was properly described by the net assimilation rate (TAL, which is also affected by the leaf area duration (DAF and leaf mass ratio (RMF.

  10. Positive Impacts of Social Media at Work: Job Satisfaction, Job Calling, and Facebook Use among Co-Workers

    Directory of Open Access Journals (Sweden)

    Hanna Brittany

    2017-01-01

    Full Text Available The number of Facebook users grew rapidly since its conception. Within today’s workplace, employees are increasingly connecting with each other on Facebook for interpersonal reasons. Due to sensational reports by media outlets of inappropriate social media use, many organizations are taking extreme measures about how their employees who utilize Facebook to connect with colleagues. Contrary to the negative assumptions, McAfee [1] states that social media within the workplace can promote positive dynamics. The present study uses McAfee’s argument to examine if a positive connection exists between colleagues who use Facebook to connect with each other. An online survey with questions involving Facebook use with co-workers, job satisfaction, and perceived job calling was completed by employees (N=70 at two high-tech companies in Northern California, USA. Results revealed that job satisfaction is positively correlated with intensity of Facebook use among co-workers. Furthermore, feeling called to one’s line of work was statistically significantly higher for the group of employees who spent the most amount of time interacting on Facebook with their co-workers than the group that spent the least amount of time. These results suggest that companies could begin to explore the positive benefits of social media use within the workplace.

  11. Pressure-induced change of the electronic state in the tetragonal phase of CaFe2As2

    International Nuclear Information System (INIS)

    Sakaguchi, Yui; Ikeda, Shugo; Kuse, Tetsuji; Kobayashi, Hisao

    2014-01-01

    We have investigated the electronic states of single-crystal CaFe 2 As 2 under hydrostatic pressure using 57 Fe Mössbauer spectroscopy and magnetization measurements. The center shift and the quadrupole splitting were refined from observed 57 Fe Mössbauer spectra using the single-crystalline sample under pressure at room temperature. A discontinuous decrease in the pressure dependence of the refined center shift was observed at 0.33 GPa without any anomaly in the pressure dependence of the refined quadrupole splitting, indicating a purely electronic state change in CaFe 2 As 2 with a tetragonal structure. Such a change is shown to be reflected in the peak-like anomalies observed in the pressure dependences of the magnetic susceptibility at 0.26 GPa above 150 K. Our results reveal that this pressure-induced electronic state change suppresses the tetragonal-to-orthorhombic structural phase transition accompanied by an antiferromagnetic ordering. We further observed superconductivity in CaFe 2 As 2 below ∼8 K around 0.33 GPa although our sample was not in a single phase at this pressure. These findings suggest that the electronic state change observed in CaFe 2 As 2 with the tetragonal structure is relevant to the appearance of the pressure-induced superconductivity in AFe 2 As 2 . (paper)

  12. Uniaxial-strain mechanical detwinning of CaFe2As2 and BaFe2As2 crystals: Optical and transport study

    International Nuclear Information System (INIS)

    Tanatar, M.A.; Blomberg, E.C.; Kreyssig, A.; Kim, M.G.; Ni, N.; Thaler, A.; Bud'ko, S.L.; Canfield, P.C.; Goldman, A.I.; Mazin, I.I.; Prozorov, R.

    2010-01-01

    The parent compounds of iron-arsenide superconductors, AFe 2 As 2 (A=Ca, Sr, Ba), undergo a tetragonal to orthorhombic structural transition at a temperature T TO in the range 135-205 K depending on the alkaline-earth element. Below T TO the free standing crystals split into equally populated structural domains, which mask intrinsic, in-plane, anisotropic properties of the materials. Here we demonstrate a way of mechanically detwinning CaFe 2 As 2 and BaFe 2 As 2 . The detwinning is nearly complete, as demonstrated by polarized light imaging and synchrotron x-ray measurements, and reversible, with twin pattern restored after strain release. Electrical resistivity measurements in the twinned and detwinned states show that resistivity, ρ, decreases along the orthorhombic a o axis but increases along the orthorhombic b o axis in both compounds. Immediately below T TO the ratio ρ bo /ρ ao = 1.2 and 1.5 for Ca and Ba compounds, respectively. Contrary to CaFe 2 As 2 , BaFe 2 As 2 reveals an anisotropy in the nominally tetragonal phase, suggesting that either fluctuations play a larger role above T TO in BaFe 2 As 2 than in CaFe 2 As 2 or that there is a higher temperature crossover or phase transition.

  13. Bioremediation of Petrochemical Wastewater Containing BTEX Compounds by a New Immobilized Bacterium Comamonas sp. JB in Magnetic Gellan Gum.

    Science.gov (United States)

    Jiang, Bei; Zhou, Zunchun; Dong, Ying; Wang, Bai; Jiang, Jingwei; Guan, Xiaoyan; Gao, Shan; Yang, Aifu; Chen, Zhong; Sun, Hongjuan

    2015-05-01

    In this study, we investigated the bioremediation of petrochemical wastewater containing BTEX compounds by immobilized Comamonas sp. JB cells. Three kinds of magnetic nanoparticles were evaluated as immobilization supports for strain JB. After comparison with Fe3O4 and a-Fe2O3 nanoparticles, r-Fe2O3 nanoparticle was selected as the optimal immobilization support. The highest biodegradation activity of r-Fe2O3-magnetically immobilized cells was obtained when the concentration of r-Fe2O3 nanoparticle was 120 mg L(-1). Additionally, the recycling experiments demonstrated that the degradation activity of r-Fe2O3-magnetically immobilized cells was still high and led to less toxicity than untreated wastewater during the eight recycles. qPCR suggested the concentration of strain JB in r-Fe2O3-magnetically immobilized cells was evidently increased after eight cycles of degradation experiments. These results supported developing efficient biocatalysts using r-Fe2O3-magnetically immobilized cells and provided a promising technique for improving biocatalysts used in the bioremediation of not only petrochemical wastewater but also other hazardous wastewater.

  14. A configurable electronics system for the ESS-Bilbao beam position monitors

    Science.gov (United States)

    Muguira, L.; Belver, D.; Etxebarria, V.; Varnasseri, S.; Arredondo, I.; del Campo, M.; Echevarria, P.; Garmendia, N.; Feuchtwanger, J.; Jugo, J.; Portilla, J.

    2013-09-01

    A versatile and configurable system has been developed in order to monitorize the beam position and to meet all the requirements of the future ESS-Bilbao Linac. At the same time the design has been conceived to be open and configurable so that it could eventually be used in different kinds of accelerators, independent of the charged particle, with minimal change. The design of the Beam Position Monitors (BPMs) system includes a test bench both for button-type pick-ups (PU) and striplines (SL), the electronic units and the control system. The electronic units consist of two main parts. The first part is an Analog Front-End (AFE) unit where the RF signals are filtered, conditioned and converted to base-band. The second part is a Digital Front-End (DFE) unit which is based on an FPGA board where the base-band signals are sampled in order to calculate the beam position, the amplitude and the phase. To manage the system a Multipurpose Controller (MC) developed at ESSB has been used. It includes the FPGA management, the EPICS integration and Archiver Instances. A description of the system and a comparison between the performance of both PU and SL BPM designs measured with this electronics system are fully described and discussed.

  15. Enhanced performance of ferroelectric materials under hydrostatic pressure

    Science.gov (United States)

    Chauhan, Aditya; Patel, Satyanarayan; Wang, Shuai; Novak, Nikola; Xu, Bai-Xiang; Lv, Peng; Vaish, Rahul; Lynch, Christopher S.

    2017-12-01

    Mechanical confinement or restricted degrees of freedom have been explored for its potential to enhance the performance of ferroelectric devices. It presents an easy and reversible method to tune the response for specific applications. However, such studies have been mainly limited to uni- or bi-axial stress. This study investigates the effect of hydrostatic pressure on the ferroelectric behavior of bulk polycrystalline Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3. Polarization versus electric field hysteresis plots were generated as a function of hydrostatic pressure for a range of operating temperatures (298-398 K). The application of hydrostatic pressure was observed to induce anti-ferroelectric like double hysteresis loops. This in turn enhances the piezoelectric, energy storage, energy harvesting, and electrocaloric effects. The hydrostatic piezoelectric coefficient (dh) was increased from 50 pCN-1 (0 MPa) to ˜900 pC N-1 (265 MPa) and ˜3200 pCN-1 (330 MPa) at 298 K. Energy storage density was observed to improve by more than 4 times under pressure, in the whole temperature range. The relative change in entropy was also observed to shift from ˜0 to 4.8 J kg-1 K-1 under an applied pressure of 325 MPa. This behavior can be attributed to the evolution of pinched hysteresis loops that have been explained using a phenomenological model. All values represent an improvement of several hundred percent compared to unbiased performance, indicating the potential benefits of the proposed methodology.

  16. First-principles approach to the dynamic magnetoelectric couplings for the non-reciprocal directional dichroism in BiFeO3

    Science.gov (United States)

    Lee, Jun Hee; Kézsmáki, István; Fishman, Randy S.

    2016-04-01

    Due to the complicated magnetic and crystallographic structures of BiFeO3, its magnetoelectric (ME) couplings and microscopic model Hamiltonian remain poorly understood. By employing a first-principles approach, we uncover all possible ME couplings associated with the spin-current (SC) and exchange-striction (ES) polarizations, and construct an appropriate Hamiltonian for the long-range spin-cycloid in BiFeO3. First-principles calculations are used to understand the microscopic origins of the ME couplings. We find that inversion symmetries broken by ferroelectric and antiferroelectric distortions induce the SC and the ES polarizations, which cooperatively produce the dynamic ME effects in BiFeO3. A model motivated by first principles reproduces the absorption difference of counter-propagating light beams called non-reciprocal directional dichroism. The current paper focuses on the spin-driven (SD) polarizations produced by a dynamic electric field, i.e. the dynamic ME couplings. Due to the inertial properties of Fe, the dynamic SD polarizations differ significantly from the static SD polarizations. Our systematic approach can be generally applied to any multiferroic material, laying the foundation for revealing hidden ME couplings on the atomic scale and for exploiting optical ME effects in the next generation of technological devices such as optical diodes. This manuscript has been written by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan.

  17. The effect of phase assemblages, grain boundaries and domain structure on the local switching behavior of rare-earth modified bismuth ferrite ceramics

    International Nuclear Information System (INIS)

    Alikin, Denis O.; Turygin, Anton P.; Walker, Julian; Bencan, Andreja; Malic, Barbara; Rojac, Tadej; Shur, Vladimir Ya.; Kholkin, Andrei L.

    2017-01-01

    Piezoelectric properties and ferroelectric/ferroelastic domain switching behavior of polycrystalline ceramics are strongly influenced by local scale (i.e. <100 nm) phenomena, such as, the phase assemblages, domain structure, and defects. The method of ceramic synthesis strongly effects the local properties and thus plays a critical role in determining the macroscopic ferroelectric and piezoelectric performance. The link between synthesis and local scale properties of ferroelectrics is, however, rarely reported, especially for the emerging lead-free materials systems. In this work, we focus on samarium modified bismuth ferrite ceramics (Bi_0_._8_8Sm_0_._1_2FeO_3, BSFO) prepared by two methods: standard solid state reaction (SSR) and mechanochemi≿ally assisted synthesis (MAS). Each ceramic possesses different properties at the local scale and we used the piezoresponse force microscopy (PFM) complemented by transmission electron microscopy (TEM) to evaluate phase distribution, domain structure and polarization switching to show that an increase in the anti-polar phase assemblages within the polar matrix leads to notable changes in the local polarization switching. SSR ceramics exhibit larger internal bias fields relative to the MAS ceramics, and the grain boundaries produce a stronger effect on the local switching response. MAS ceramics were able to nucleate domains at lower electric-fields and grow them at faster rates, reaching larger final domain sizes than the SSR ceramics. Local evidence of the electric-field induced phase transition from the anti-ferroelectric Pbam to ferroelectric R3c phase was observed together with likely evidence of the existence of head-to-head/tail-to-tail charged domain walls and domain vortex core structures. By comparing the domain structure and local switching behavior of ceramics prepared by two different methods this work brings new insights the synthesis-structure-property relationship in lead-free piezoceramics.

  18. Polar-antipolar transition and weak ferromagnetism in Mn-doped Bi0.86La0.14FeO3

    Science.gov (United States)

    Khomchenko, V. A.; Karpinsky, D. V.; Troyanchuk, I. O.; Sikolenko, V. V.; Többens, D. M.; Ivanov, M. S.; Silibin, M. V.; Rai, R.; Paixão, J. A.

    2018-04-01

    Having been considered as a prime example of a room-temperature magnetoelectric multiferroic, BiFeO3 continues to attract much interest. Since functional properties of this material can be effectively influenced by chemical, electrical, magnetic, mechanical and thermal stimuli, it can serve as a model for the investigation of cross-coupling phenomena in solids. Special attention is currently paid to the study of chemical pressure-driven magneto-structural transformations. In this paper, we report on the effect of the Mn doping on the crystal structure and magnetic behavior of the Bi1‑x La x FeO3 multiferroics near their polar-antipolar (antiferromagnetic-weak ferromagnetic) phase boundary. Synchrotron x-ray and neutron powder diffraction measurements of the Bi0.86La0.14Fe1‑x Mn x O3 (x  =  0.05, 0.1, 0.15) compounds have been performed. The diffraction data suggest that the Mn substitution results in the suppression of the ferroelectric polarization and gives rise to the appearance of the antiferroelectric (generally, PbZrO3-related) phase characteristic of the phase diagrams of the Bi1‑x RE x FeO3 (RE  =  rare-earth) systems. Depending on the Mn concentration (determining phase composition of the Bi0.86La0.14Fe1‑x Mn x O3 samples at room temperature), either complete or partial revival of the polar phase can be observed with increasing temperature. Magnetic measurements of the samples indicate that the Mn doping affects the stability of the cycloidal antiferromagnetic order specific to the polar phase, thus resulting in the formation of a ferroelectric and weak ferromagnetic state.

  19. Ethephon on the growth of squash plants in protected environment / Aplicação de ethephon em plantas de abobrinha (Curcubita pepo var. melopepo cultivadas em casa de vegetação

    Directory of Open Access Journals (Sweden)

    Rumy Goto

    2000-04-01

    Full Text Available The aim of this work was to study the effect of Ethephon on the growth of squash plants, under conditions of protected environment. The application of Ethephon at 200 and 400 mgt1, was carried out in two stages of development, 2nd and 4th true leaf. The growth of the plants was evaluated with the following parameters of the growth analysis: Leaf Area Ratio (g.g1 - LAR; Specific Leaf Area (cm2.g1 - SLA; Leaf Mass Ratio (9-91 - LMR; Relative Growth Rate (g.g-1 .day1 - RGR and Net Assimilation Rate (g.cm2.day1 - NAR. The LAR increased from the first to the second collect to decreased soon after that, being that the Ethephon 400 mg.L1 applied in the stage of 4th true leaf presented difference to the 57 DAS (days after seeding. The SLA curves are increasing in the beginning of the development, presenting reduction through the long of the cycle. How much the LMR all the treatments had presented similar behaviour, not evidencing effect of Ethephon application. Ethephon 200 mg.L1 applied in the stage of 4th true leaf presented constant values of RGR. All the treatments had presented at least two peaks of NAR values and except for control, showed decreasing results in the last interval.O trabalho objetivou estudar o efeito do ethephon sobre o crescimento de plantas de abobrinha sob condições de ambiente protegido. As aplicações de ethephon a 200 e 400 mg.L foram realizadas nos estádios de 2ã e 4a folha verdadeira, sendo a primeira aos 22 DAS (dias após a semeadura e a segunda aos 30 DAS. O crescimento das plantas foi avaliado através dos seguintes parâmetros: razão de área foliar (cm2.g1 - RAF; área foliar específica (cm2.g1 - AFE; razão de massa foliar (g.g1 - RMF; taxa de crescimento relativo (g.g-1 .dia-1 - TCR e taxa assimilatória líquida (g.cm-2.dia-1 - TAL. A RAF aumentou da 1ã para a 2a coleta para diminuir logo em seguida, sendo que o tratamento com ethephon 400 mg.L-1, aplicado no estádio de 4a folha verdadeira, apresentou

  20. Synthesis and structural, magnetic, thermal, and transport properties of several transition metal oxides and aresnides

    Energy Technology Data Exchange (ETDEWEB)

    Das, Supriyo [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and an- tiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides VnO2n-1 where 2 ≤ n ≤ 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions.[1–6] The only exception is V7O13 which remains metallic down to 4 K.[7] The ternary vanadium oxide LiV2O4 has the normal spinel structure, is metallic, does not un- dergo magnetic ordering and exhibits heavy fermion behavior below 10 K.[8] CaV2O4 has an orthorhombic structure[9, 10] with the vanadium spins forming zigzag chains and has been suggested to be a model system to study the gapless chiral phase.[11, 12] These provide great motivation for further investigation of some known vanadium compounds as well as to ex- plore new vanadium compounds in search of new physics. This thesis consists, in part, of experimental studies involving sample preparation and magnetic, transport, thermal, and x- ray measurements on some strongly correlated eletron systems containing the transition metal vanadium. The compounds studied are LiV2O4, YV4O8, and YbV4O8. The recent discovery of superconductivity in RFeAsO1-xFx (R = La, Ce, Pr, Gd, Tb, Dy, Sm, and Nd), and AFe2As2 (A = Ba, Sr, Ca, and Eu) doped with K, Na, or Cs at the A site with relatively high Tc has sparked tremendous activities in the condensed matter physics community and a renewed interest in the area of superconductivity as occurred following the discovery of the layered cuprate high Tc superconductors in 1986. To discover more supercon- ductors

  1. Fotosíntesis en tres poblaciones altitudinales de la planta andina Espeletia schultzii (Compositae

    Directory of Open Access Journals (Sweden)

    Marisol Castrillo

    2006-12-01

    Full Text Available Resumen Se establece una comparación de algunos parámetros fotosintéticos: actividad Rubisco (Ribulosa 1, 5-bis-fosfato carboxilasa EC 4.1.1.39 contenidos de clorofilas, azúcares solubles totales y proteínas solubles totales y área foliar específica (AFE, en tres poblaciones altitudinales de Espeletia schultzii ubicadas a 3 100, 3 550 y 4 200 msnm. De acuerdo con el análisis de varianza la población a 4 200 m presentó una actividad Rubisco significativamente mayor que las otras dos, en cuyos casos los valores no fueron diferentes. Los contenidos de clorofila a presentan una leve tendencia a la disminución con la altura; mientras que la clorofila b se mantiene constante, razón por la cual la relación a/b (R a/b disminuye con la elevación, aunque, las diferencias no son significativas. El contenido de azúcares en cada una de las poblaciones estudiadas (gm-2, aumenta con la elevación; las diferencias entre las poblaciones son significativas. Con relación al contenido de proteínas, no existen diferencias entre las poblaciones estudiadas. El área foliar específica (AFE disminuye significativamente con la altura. Es probable que el incremento en la actividad Rubisco sea producido por una mayor activación de la enzima y no por el mayor contenido de proteína. Los azúcares solubles presentan incremento significativo, este hecho es probable que se encuentre asociado con la actividad Rubisco. De los cinco parámetros fotosintéticos medidos, tres presentan diferencias significativas asociadas con la altitud. Esto representa un compromiso entre una mayor actividad metabólica mantenida en un menor volumen celularPhotosynthesis in three altitudinal populations of the Andean plant Espeletia schultzii (Compositae. Photosynthesis was compared in three altitudinal populations of Espeletia schultzii: 3 100, 3 550 and 4 200 masl. The measured parameters were Rubisco activity (EC 4.1.139, chlorophyll, soluble protein and soluble sugars

  2. Allometric models for determining leaf area in the ‘PH-16’ cocoa tree in the shade and in full sun = Modelos alométricos para determinação da área foliar de cacaueiro ‘PH-16’ em sombreamento e pleno sol

    Directory of Open Access Journals (Sweden)

    Edilson Romais Schmildt

    2017-03-01

    Full Text Available The aim of this work was to study the statistical modelling of leaf area in the cocoa tree (Theobroma cacao L. ‘PH - 16’, in a shaded environment and in full sun. Two hundred leaves (100 from plants grown in the shade and 100 grown in full sun were randomly collected from cacao plants in plantations in the city of Linhares in the State of Espírito Santo, Brazil, to study their linear measurements. The leaves were separated into two groups, one to estimate the equations and the other to validate the equations. All leaves were characterised for length (C, width (L and leaf area. Leaf area was estimated by linear, power and exponential models from the measurements of C, L and CL as independent variables. When validating the equations, the equation proposed by Azomaning and Lockard was also evaluated. There is a difference in leaf morphology between cocoa grown in the shade and in full sun, however the environment does not statistically affect the intercept in the linear and power models, justifying modelling from the joint use of leaves of the two environments. It is possible to estimate leaf area in the cocoa plant from allometric equations, with the equations that use the product of CL as the explanatory variable being more precise. The power model equation AFE = 0.6736 (LW1.0036 is best suited for estimating leaf area in ‘PH-16’ cocoa, and can be used both for the leaves of plants in shaded environments and in full sun. = Objetivou-se com este trabalho estudar a modelagem estatística da área foliar de cacaueiro (Theobroma cacao L. ‘PH-16’, em ambiente sombreado e a pleno sol. Coletaram-se aleatoriamente 200 folhas de cacaueiro (100 foram de plantas em cultivo sombreado e 100 em cultivo a pleno sol, situadas em lavouras cacaueiras no município de Linhares (ES, para estudo de suas medidas lineares. As folhas foram separadas em dois grupos, um para estimativa das equações e outro para validação dessas equações. Todas as folhas

  3. Tradução e validação da adaptação para o exercício do Perceived Motivational Climate Sport Questionnaire Translation and validation of the exercise adaptation of the Perceived Motivational Climate Sport Questionnaire

    Directory of Open Access Journals (Sweden)

    Luís Cid

    2012-12-01

    Full Text Available O objetivo principal do estudo é a tradução e validação da versão portuguesa da adaptação ao exercício do Perceived Motivational Climate in Sport Questionnaire (PMCSQ, com recurso à análise fatorial exploratória (AFE e confirmatória (AFC, realizadas com dois grupos independentes de praticantes de exercício em ginásios, de ambos os géneros e com idades compreendidas entre os 14 e os 64 anos. Na AFE os resultados revelam uma estrutura que explica 52% da variância dos resultados, pesos fatoriais entre 0.63 e 0.80, e uma boa consistência interna (αMestria=0.78; αPerformance=0.74. Na AFC os resultados indicam um excelente ajustamento do modelo: S-Bχ²=40.6; df=34; p=0.20; S-Bχ²/df=1.19; SRMR=0.03; NNFI=0.98; CFI=0.99; RMSEA=0.02; 90% IC RMSEA=0.00-0.05, uma consistência interna razoável (αMestria=0.74; αPerformance=0.75, e pesos fatoriais entre 0.50 e 0.79, o que nos leva a concluir que a versão Portuguesa da adaptação do PMCSQ ao exercício pode ser utilizada na avaliação do clima motivacional no exercício.The main purpose of this study is to present the results of translation and validation of the Portuguese version of Perceived Motivational Climate in Sport Questionnaire (PMCSQ adaptation to exercise, through exploratory (EFA and confirmatory (CFA factor analysis, performed with two independent groups of participants, all exercisers in private fitness clubs, of both sexes, and aged between 14 and 64 years old. The EFA results reveal a structure explaining 52% of total variance, with factor loadings ranged from 0.63 to 0.80, and reasonable reliability (αMastery=0.78; αPerformance=0.74. The AFC results showed an excellent model fit to data: S-Bχ²=40.6; df=34; p=0.20; S-Bχ²/df=1.19; SRMR=0.03; NNFI=0.98; CFI=0.99; RMSEA=0.02; 90% IC RMSEA=0.00-0.05, an acceptable reliability (αMastery=0.74; αPerformance=0.75, and factor loadings ranged from 0.50 to 0.79, which leads us to conclude that Portuguese version of

  4. Sulfur Concentration at Sulfide Saturation in Anhydrous Silicate Melts at Crustal Conditions

    Science.gov (United States)

    Liu, Y.; Samaha, N.; Baker, D. R.

    2006-05-01

    The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1250°C to 1450°C and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic. All experiments were saturated with a FeS melt. Temperature was confirmed to have a positive effect on the SCSS and no measurable pressure effect was observed. Oxygen fugacity was controlled to be either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. A series of models were constructed to predict the SCSS as a function of temperature, pressure, melt composition, oxygen fugacity and sulfur fugacity of the system. The coefficients were obtained by the regression of experimental data from this study and from data in the literature. The best model found for the prediction of the SCSS is: ln S (ppm) = 996/T + 9.875 + 0.997 ln MFM + 0.1901 ln fO2 - 0.0722 (P/T) -0.115 ln f S2, where P is in bar, T is in K, and MFM is a compositional parameter describing the melt based upon cation mole fractions: MFM = [Na + K + 2 (Ca + Mg+ Fe2+)]/[Si × (Al + Fe3+)]. This model predicts the SCSS in anhydrous silicate melts from rhyolitic to basaltic compositions at crustal conditions from 1 bar to 1.25 GPa, temperatures from ~1200 to 1400 C, and oxygen fugacities between approximately two log units below the fayalite-quartz-magnetite buffer and one log unit above the nickel-nickel oxide buffer. For cases where the oxygen and sulfur fugacities can not be adequately estimated a simpler model also works acceptably: ln S (ppm) = -5328/T + 8.431 + 1.244 ln MFM - 0.01704(P/T) + ln aFeS, where aFeS is the activity of FeS in the sulfide melt and is well approximated by a value of 1. Additional experiments were performed on other basalts in a temperature range from 1250 C to 1450 C at 1 GPa to test the models. The model

  5. Efecto de la adición de Gd2O3 sobre las propiedades magnéticas de hexaferritas de estroncio

    Directory of Open Access Journals (Sweden)

    Sánchez Ll., J. L.

    1999-12-01

    Full Text Available The hexaferrites (AFe12O19, A = Ba, Sr have been used since years ago. Because of their low cost these materials continue in the market and they have not been substituted for other powerful magnets. The partial substitution of metallic elements or the use of additives in small proportions have been widely used for industrial processes in order to improve magnetic properties or the sintering process. Efforts had been made to determinate the effect of an important number of diamagnetic or paramagnetic cations on the microstructure and magnetic properties of the hexagonal ferrites. Previous studies have reported a remarkable increase in the coercitive field of the hexaferrites of barium with the substitution partial of that by La, Lu, Sm, Nd and Gd. In the present research a structural and magnetic study of sintered permanent magnets with the general formula Sr1-XGdX/2NaX/2Fe12O19 (0.00≤ X ≤0.10 was made. The samples were characterized by X-ray diffraction, vibrating sample magnetometry, scanning electron microscopy and elemental analysis (EDAX. The dependency of the densification, the medium grain size, the cells parameters and the magnetic properties with the gadolinium oxide content is discussed.Las hexaferritas (AFe12O19, A = Ba, Sr se vienen utilizando desde hace varios años; debido a su bajo costo dominan el mercado y no han sido sustituidas por imanes permanentes más potentes. La sustitución parcial de los elementos metálicos o la utilización de aditivos en pequeña proporción ha sido ampliamente utilizada en la industria con el objeto de mejorar las propiedades magnéticas o facilitar el proceso de sinterización. Se han dedicado esfuerzos importantes para determinar el efecto de un número importante de iones diamagnéticos y paramagnéticos sobre la microestructura y las propiedades magnéticas de las ferritas hexagonales. Trabajos previos reportaron un aumento notable del campo coercitivo en hexaferritas de bario con substituci

  6. Cambios ontogénicos en la morfología de plántulas de Manilkara zapota: análisis de sus implicaciones ecológicas Ontogenetic changes in seedling morphology of Manilkara zapota: analysis of ecological implications

    Directory of Open Access Journals (Sweden)

    Juan Antonio Cruz-Rodríguez

    2010-04-01

    Full Text Available En este trabajo se describen los cambios ontogénicos que se presentan en la morfología de plántulas de Manilkara zapota, uno de los árboles más abundantes de las selvas neotropicales. Estas plántulas presentan cambios morfológicos que se relacionan significativamente con sus probabilidades de supervivencia. La variación se describe a partir del registro y la observación de 552 plántulas con alturas menores a 35 cm, localizadas en una selva mediana subperennifolia en la parte central del estado de Veracruz. De cada individuo se registró presencia de cotiledones, altura, número de hojas, longitud y forma de las hojas, cobertura y área foliar específica (AFE. Con base en la forma de las hojas, se distinguieron 4 variantes: a plántulas con cotiledones; b plántulas con hojas elípticas; c plántulas con hojas oblongas, y d plántulas con hojas oblongolanceoladas. El tamaño de las hojas de la última clase fue de hasta 30 cm y duplica el tamaño de las hojas de los árboles adultos. El AFE mostró una correlación negativa con el tamaño de la hoja, lo que sugiere costos de construcción altos en las hojas grandes y explica su ausencia en los primeros años de vida. La formación de hojas grandes es un proceso discontinuo que depende de las reservas de la plántula y que permite aprovechar la escasa radiación prevaleciente en sotobosque.In this work the variability in seedling morphology of one of the most abundant neotropical trees, Manilkara zapota, is described. These seedlings display morphological changes significantly related with their survival probabilities. The variation is described from observations of 552 seedlings with heights less than 35 cm, in a subtropical rain forest in the central portion of the state of Veracruz. From each seedling we gathered the following data: presence of cotyledons, height, number of leaves, length and shape of the leaves, cover, and specific leaf area (SLA. Based on leaf shape, 4 seedling

  7. The effect of synthetic method and annealing temperature on metal site preference in Al(1-x)Ga(x)FeO3.

    Science.gov (United States)

    Walker, James D S; Grosvenor, Andrew P

    2013-08-05

    Magnetoelectric materials couple both magnetic and electronic properties, making them attractive for use in multifunctional devices. The magnetoelectric AFeO3 compounds (Pna2(1); A = Al, Ga) have received attention as the properties of the system depend on composition as well as the synthetic method used. Al(1-x)Ga(x)FeO3. (0 ≤ x ≤ 1) was synthesized by the sol-gel and coprecipitation methods and studied by X-ray absorption near-edge spectroscopy (XANES). Al L(2,3-), Ga K-, and Fe K-edge XANES spectra were collected to examine how the average metal coordination number (CN) changes with the synthetic method. Al and Fe were found to prefer octahedral sites, while Ga prefers the tetrahedral site. It was found that composition played a larger role in determining site occupancies than synthetic method. Samples made by the sol-gel or ceramic methods (reported previously; Walker, J. D. S.; Grosvenor, A. P. J. Solid State Chem. 2013, 197, 147-153) showed smaller spectral changes than samples made via the coprecipitation method. This is attributed to greater ion mobility in samples synthesized via coprecipitation as the reactants do not have a long-range polymeric or oxide network during synthesis like samples synthesized via the sol-gel or ceramic method. Increasing annealing temperature increases the average coordination number of Al, and to a lesser extent Ga, while the average coordination number of Fe decreases. This study indicates that greater disorder is observed when the Al(1-x)Ga(x)FeO3. compounds have high Al content, and when annealed at higher temperatures.

  8. Effects of exogenous retinol and retinoic acid on the biosynthesis of 14C-mannose labelled glycolipids and glycoproteins in rat liver

    International Nuclear Information System (INIS)

    Sato, Mayumi; DeLuca, L.M.; Muto, Yasutoshi

    1978-01-01

    The in vivo and in vitro effects of retinol and retionic acid was investigated on the synthesis of mannolipids and mannopeptides in rat liver. Weanling male, Wister-strain rats (Japan Clea Inc., Tokyo), weighing 35 to 40g are housed in hanging wire bottom cages and maintained on a vitamin A-deficient diet. The incorporation of 14 C-mannose into glycolipids and glycoproteins showed a decrease in vitamin A-depleted rats as compared with vitamin A-fed rats. The mannose-containing lipids were separated into retinyl phosphate (MRP, R sub(f) 0.2) and dolichyl mannosyl phosphate (DMP, R sub(f) 0.4), respectively, by DEAE-cellulose, silicic acid and thin-layer chromatography. A rapid increase in the synthesis of labelled MPR was observed, exhibiting a peak between 25 and 60 minutes after intraperitoneal administration of retinol to vitamin A-depleted rats. Similarly, administration of retionic acid brought about elevation of 14 C-mannolipid (R sub(f) 0.2) synthesis with a peak at 60 minutes after injection. On the other hand, the incorporation of 14 C-mannose into DMP (R sub(f) 0.4) remained unchanged by such treatment. These results suggest that not only retinol but also retionic acid plays an important biological role in manosyl transfer reaction in rat liver. However, the molecular participation of a metabolite of retionic acid in the formation of manolipid and the structure of such a metabolite remain to be established. (Iwakiri, K.)

  9. Escalas de depresión y ansiedad para personas transexuales

    Directory of Open Access Journals (Sweden)

    José Miguel Rodríguez Molina

    2015-01-01

    Full Text Available La transexualidad es un fenómeno emergente. Es necesario evaluar no solo la presencia de transexualidad sino también todas las variables de proceso. Este estudio tuvo como objetivo presentar y analizar las propiedades psicométricas de dos instrumentos de evaluación en población transexual; uno para evaluar ansiedad y otro depresión. Se llevó a cabo la construcción cualitativa de las dos escalas y se validó su contenido mediante su aplicación a 154 sujetos. Se calcularon la validez de criterio y la fiabilidad mediante el Alfa de Cronbach y se ejecutó un Análisis Factorial Exploratorio. Se obtuvieron datos de alta significación estadística para la fiabilidad de las escalas (para ESANTRA un Alfa de Cronbach de .958 y correlación entre mitades de .926 y para ESDETRA un Alfa de Cronbach de .967 y correlación entre mitades de .958 y también para todos los elementos de ambas, así como una alta validez de criterio (para ESANTRA de .782 con p< .001 con el ISRA y para ESDETRA .829 con p< .001 con el BDI. El AFE mostró un único factor explicativo en cada escala (con varianza explicada del 45.71% ESANTRA y 51.55% ESDETRA. Las escalas ESANTRA y ESDETRA parecen ser útiles para la evaluación de ansiedad y depresión en personas transexuales.

  10. Synthesis and characterization of two novel chiral-type formate frameworks templated by protonated diethylamine and ammonium cations

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland); Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland); Hanuza, Jerzy [Department of Bioorganic Chemistry, University of Economics, 53 345 Wroclaw (Poland); Pikul, Adam; Drozd, Marek [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland)

    2017-01-15

    Two novel formate frameworks templated by ammonium and diethylammonium (DEtA{sup +}) cations have been synthesized. Chemical analysis as well as optical, Raman and IR studies showed partial substitution of nickel ions by Cr(III) or Fe(III). X-ray diffraction revealed that these compounds crystallize in the chiral-type structure of P6{sub 3}22 symmetry. The oxygen atoms from formate ligands form octahedral coordination around the metal centers and the octahedra are bridged by the formate groups in the anti-anti mode configuration forming the hexagonal structure with large channels expanding along the c direction. The channels are filled with disordered DEtA{sup +} and NH{sub 4}{sup +} ions and they show unusual compression with the c/a ratio of only 0.862 and 0.852 for the iron- and chromium-containing compound, respectively. Magnetic studies revealed that the both compounds order magnetically at low temperatures but the ordering temperature is significantly higher for the iron compound (37 K) compared to the chromium analogue (26 K). - Graphical abstract: Temperature dependence of magnetization M of DEtAFeNi showing magnetic order at 37 K. - Highlights: • Two novel chiral formates of P6{sub 3}22 symmetry were synthesized. • The structures contain strongly compressed hexagonal channels filled with disordered cations. • The obtained compounds exhibit magnetic order at low temperatures. • Raman, IR and absorption spectra prove incorporation of Cr(III) and Fe(III) in the frameworks.

  11. Análisis y valoración de la aplicación de sistemas de gestión de la calidad ISO 9001 y su incidencia en centros educativos

    Directory of Open Access Journals (Sweden)

    Jorge Antonio Arribas Díaz

    2017-10-01

    Full Text Available INTRODUCCIÓN. El objetivo principal de esta investigación es analizar y valorar el Sistema de Gestión de la Calidad (SGC, basado en la Norma ISO 9001, incorporado en 26 centros educativos de la Fundación Escuelas Profesionales de la Sagrada Familia (SAFA, a partir de las valoraciones de sus usuarios y de los resultados que consigue en la organización y en la formación de sus alumnos. MÉTODO. Utilizando una metodología propia de la investigación evaluativa, se ha recogido información mediante las técnicas del cuestionario, la observación, las entrevistas, el análisis de la documentación (informes de auditorías y no conformidades y del rendimiento del alumnado. Las del cuestionario cumplen con las características de validez de expertos, fiabilidad y AFE. RESULTADOS. Los análisis descriptivos y discriminantes realizados sobre la información recogida, aportan la existencia de relaciones entre la aplicación del SGC basado en ISO en los centros educativos y la mejora de su organización escolar y de sus resultados. Se puede decir que los centros en los que su profesorado considera que el SGC aporta mejoras a la organización escolar y en los resultados que consigue, son centros con mayor nivel en determinados resultados educativos. DISCUSIÓN. La norma ISO 9001 y su SGC adaptada adecuadamente en los ámbitos educativos, consigue resultados inmediatos y perdurables en el tiempo, que contribuyen a la mejora de la educación, y aportan valor a los centros educativos. Estos resultados los hace sustentables en la institución estudiada y aconsejable su utilización en otras organizaciones educativas.

  12. Serum and hepatic vitamin A levels in captive and wild marine toads (Bufo marinus).

    Science.gov (United States)

    Berkvens, Charlene N; Lentini, Andrew; Dutton, Christopher J; Pearl, David L; Barker, Ian K; Crawshaw, Graham J

    2014-01-01

    The captive breeding program for the endangered Puerto Rican crested toad (Peltophryne [Bufo] lemur) has been hampered by an undiagnosed condition called "Brown Skin Disease" (BSD). Toads develop widespread skin darkening, skin thickening and abnormal shedding and eventually succumb to a chronic loss of viability. This project evaluated the marine toad (Bufo marinus) as a model for the PRCT, examining vitamin A deficiency as a potential cause of BSD. Wild caught marine toads had significantly higher liver vitamin A concentrations (61.89 ± 63.49 µg/g) than captive born marine toads (0.58 ± 0.59 µg/g); P<0.001). A significant difference in serum vitamin A concentration was found between the captive and wild caught toads (P=0.013) and between the low vitamin A-fed and wild caught toads (P=0.004), when controlling for liver vitamin A concentrations. After captive toads were treated with topical and/or oral vitamin A, their hepatic vitamin A concentrations were similar to those of the wild toads, averaging 48.41 ± 37.03 µg/g. However, plasma vitamin A concentrations pre- and post-vitamin A supplementation did not differ statistically. We concluded that plasma vitamin A concentrations do not provide a linear indication of liver/body vitamin A status, and that both topical and oral supplementation with an oil-based vitamin A formulation can increase liver stores in amphibians. No evidence of BSD or other signs of deficiency were noted in the marine toads, although this feeding trial was relatively short (127 days). To date, clinical, pathological and research findings do not support vitamin A deficiency as a primary factor underlying BSD. © 2014 Wiley Periodicals, Inc.

  13. Peer sexual cybervictimization in adolescents: Development and validation of a scale

    Directory of Open Access Journals (Sweden)

    Virginia Sánchez

    2017-01-01

    Full Text Available Antecedentes/Objetivo: El estudio de la ciberconducta sexual en la adolescencia ha recibido mucha atención en los últimos a˜nos, especialmente la referida a los riesgos que suponen la exposición a la pornografía, las solicitudes sexuales indeseadas y el hostigamiento sexual basado en el género. La prevalencia del fenómeno varía entre los diferentes estudios debido a una falta de consenso en la definición y medida del constructo cibervictimización sexual. Este trabajo pretende contribuir en esta área, desarrollando y validando una escala para medir victimización sexual online. Método: Una muestra de 601 adolescentes de dos ciudades espa˜nolas (edad media 14,06 participaron en el estudio. Se realizó una validación cruzada empleando AFE y AFC, así como un análisis multigrupo para comparar la equivalencia de la medida por sexo. Resultados: se confirmó un modelo de segundo orden compuesto por dos factores (Cibervictimización sexual ambigua y Cibervictimización sexual personal invariante por sexo. Los análisis indicaron diferencias significativas en la dimensión ambigua, siendo más frecuente en ellos. Los datos revelaron una prevalencia entre el 17 y 26%, siendo menor la implicación en la forma personal. Conclusiones: Se propone una medida válida e invariante en ambos sexos de la cibervictimización sexual por parte de los iguales en la adolescencia.

  14. Método não destrutivo para determinação da área foliar da videira, cultivar BRS-Violeta

    Directory of Open Access Journals (Sweden)

    Gustavo Malagi

    2010-12-01

    Full Text Available Este trabalho teve por objetivo avaliar as combinações entre o comprimento das nervuras secundárias e principal de folhas na estimativa da área foliar da videira cultivar BRS-Violeta. Realizou-se a coleta aleatória de 200 folhas intactas e completamente desenvolvidas, em uma área de cultivo experimental. Determinaram-se a área foliar real (AFR e o comprimento das nervuras secundárias (esquerda - direita e principal. Obtiveram-se três regressões com seus coeficientes de determinação para a identificação da relação mais precisa, considerando o comprimento da nervura principal (CNP, o somatório do comprimento das nervuras secundárias (SCNS e o somatório entre o comprimento das nervuras secundárias e o comprimento da nervura principal (SCNSP, como variáveis independentes. A AFR foi considerada variável dependente nas três regressões. Observou-se que a relação entre AFR x SCNS proporcionou o maior coeficiente de determinação (0,87. A área foliar estimada pela equação obtida pela relação AFR x SCNS garantiu uma precisão de 87%, segundo a relação entre AFR x AFE (área foliar estimada. Portanto, conclui-se que a área foliar da videira cultivar BRS-Violeta pode ser estimada pela equação y = 0,2169 (SCNS² + 5,3642 (SCNS - 34,725, com precisão satisfatória.

  15. A configurable electronics system for the ESS-Bilbao beam position monitors

    International Nuclear Information System (INIS)

    Muguira, L.; Belver, D.; Etxebarria, V.; Varnasseri, S.; Arredondo, I.; Campo, M. del; Echevarria, P.; Garmendia, N.; Feuchtwanger, J.; Jugo, J.; Portilla, J.

    2013-01-01

    A versatile and configurable system has been developed in order to monitorize the beam position and to meet all the requirements of the future ESS-Bilbao Linac. At the same time the design has been conceived to be open and configurable so that it could eventually be used in different kinds of accelerators, independent of the charged particle, with minimal change. The design of the Beam Position Monitors (BPMs) system includes a test bench both for button-type pick-ups (PU) and striplines (SL), the electronic units and the control system. The electronic units consist of two main parts. The first part is an Analog Front-End (AFE) unit where the RF signals are filtered, conditioned and converted to base-band. The second part is a Digital Front-End (DFE) unit which is based on an FPGA board where the base-band signals are sampled in order to calculate the beam position, the amplitude and the phase. To manage the system a Multipurpose Controller (MC) developed at ESSB has been used. It includes the FPGA management, the EPICS integration and Archiver Instances. A description of the system and a comparison between the performance of both PU and SL BPM designs measured with this electronics system are fully described and discussed. -- Author-Highlights: • A versatile and configurable BPM system for the ESS-Bilbao Linac has been designed. • The design works for PU and SL detectors, both in continuous and pulsed wave modes. • Several tests at simulated beamlines at 352 MHz and 175 MHz have been performed. • The BPM system has been integrated in EPICS and Archiver

  16. Three-Dimensional Structures of Thermal Tides Simulated by a Venus GCM

    Science.gov (United States)

    Takagi, Masahiro; Sugimoto, Norihiko; Ando, Hiroki; Matsuda, Yoshihisa

    2018-02-01

    Thermal tides in the Venus atmosphere are investigated by using a GCM named as AFES-Venus. The three-dimensional structures of wind and temperature associated with the thermal tides obtained in our model are fully examined and compared with observations. The result shows that the wind and temperature distributions of the thermal tides depend complexly on latitude and altitude in the cloud layer, mainly because they consist of vertically propagating and trapped modes with zonal wave numbers of 1-4, each of which predominates in different latitudes and altitudes under the influence of mid- and high-latitude jets. A strong circulation between the subsolar and antisolar (SS-AS) points, which is equivalent to a diurnal component of the thermal tides, is superposed on the superrotation. The vertical velocity of SS-AS circulation is about 10 times larger than that of the zonal-mean meridional circulation (ZMMC) in 60-70 km altitudes. It is suggested that the SS-AS circulation could contribute to the material transport, and its upward motion might be related to the UV dark region observed in the subsolar and early afternoon regions in low latitudes. The terdiurnal and quaterdiurnal tides, which may be excited by the nonlinear interactions among the diurnal and semidiurnal tides in middle and high latitudes, are detected in the solar-fixed Y-shape structure formed in the vertical wind field in the upper cloud layer. The ZMMC is weak and has a complex structure in the cloud layer; the Hadley circulation is confined to latitudes equatorward of 30°, and the Ferrel-like one appears in middle and high latitudes.

  17. On analyzing free-response data on location level

    Science.gov (United States)

    Bandos, Andriy I.; Obuchowski, Nancy A.

    2017-03-01

    Free-response ROC (FROC) data are typically collected when primary question of interest is focused on the proportions of the correct detection-localization of known targets and frequencies of false positive responses, which can be multiple per subject (image). These studies are particularly relevant for CAD and related applications. The fundamental tool of the location-level FROC analysis is the FROC curve. Although there are many methods of FROC analysis, as we describe in this work, some of the standard and popular approaches, while important, are not suitable for analyzing specifically the location-level FROC performance as summarized by the FROC curve. Analysis of the FROC curve, on the other hand, might not be straightforward. Recently we developed an approach for the location-level analysis of the FROC data using the well-known tools for clustered ROC analysis. In the current work, based on previously developed concepts, and using specific examples, we demonstrate the key reasons why specifically location-level FROC performance cannot be fully addressed by the common approaches as well as illustrate the proposed solution. Specifically, we consider the two most salient FROC approaches, namely JAFROC and the area under the exponentially transformed FROC curve (AFE) and show that clearly superior FROC curves can have lower values for these indices. We describe the specific features that make these approaches inconsistent with FROC curves. This work illustrates some caveats for using the common approaches for location-level FROC analysis and provides guidelines for the appropriate assessment or comparison of FROC systems.

  18. A Self-Sustained Wireless Multi-Sensor Platform Integrated with Printable Organic Sensors for Indoor Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Chun-Chang Wu

    2017-03-01

    Full Text Available A self-sustained multi-sensor platform for indoor environmental monitoring is proposed in this paper. To reduce the cost and power consumption of the sensing platform, in the developed platform, organic materials of PEDOT:PSS and PEDOT:PSS/EB-PANI are used as the sensing films for humidity and CO2 detection, respectively. Different from traditional gas sensors, these organic sensing films can operate at room temperature without heating processes or infrared transceivers so that the power consumption of the developed humidity and the CO2 sensors can be as low as 10 μW and 5 μW, respectively. To cooperate with these low-power sensors, a Complementary Metal-Oxide-Semiconductor (CMOS system-on-chip (SoC is designed to amplify and to read out multiple sensor signals with low power consumption. The developed SoC includes an analog-front-end interface circuit (AFE, an analog-to-digital convertor (ADC, a digital controller and a power management unit (PMU. Scheduled by the digital controller, the sensing circuits are power gated with a small duty-cycle to reduce the average power consumption to 3.2 μW. The designed PMU converts the power scavenged from a dye sensitized solar cell (DSSC module into required supply voltages for SoC circuits operation under typical indoor illuminance conditions. To our knowledge, this is the first multiple environmental parameters (Temperature/CO2/Humidity sensing platform that demonstrates a true self-powering functionality for long-term operations.

  19. Propiedades psicométricas y valores normativos del General Health Questionnaire (GHQ-12 en población general española

    Directory of Open Access Journals (Sweden)

    Kátia B. Rocha

    2011-01-01

    Full Text Available El objetivo principal del presente estudio es analizar las propiedades psicométricas del General Health Questionnaire (GHQ-12 como un instrumento de cribado en una muestra representativa de la población española, y en población mayor de 65 años. Se trata de un estudio instrumental utilizando los datos de la Encuesta Nacional de Salud de España (2006. Fueron entrevistadas 29.476 personas mayores de 16 años, no institucionalizadas. Se realizaron análisis de correlación entre ítems, análisis de consistencia interna, un análisis factorial exploratorio (AFE y un análisis de validez externa del GHQ-12. Todos los análisis fueron realizados utilizando dos métodos de puntuación (Likert y GHQ. Los resultados muestran que cada uno de los ítems del GHQ se correlaciona con los demás, presentando valores de correlación superiores a 0,51. El análisis factorial exploratorio confirma que gran parte de la variabilidad del instrumento (67% Likert y 73% GHQ puede ser explicada al reunir todos los ítems en un único factor. El GHQ-12 presenta una elevada consistencia interna en población general y también en población mayor de 65 años. Los análisis factoriales confirman que el GHQ-12 puede ser utilizado como un instrumento unidimensional de cribado y la puntuación más adecuada en este caso es la puntuación GHQ.

  20. Column-integrated aerosol optical properties and direct radiative forcing over the urban-industrial megacity Nanjing in the Yangtze River Delta, China.

    Science.gov (United States)

    Kang, Na; Kumar, K Raghavendra; Yu, Xingna; Yin, Yan

    2016-09-01

    Aerosol optical properties were measured and analyzed through the ground-based remote sensing Aerosol Robotic Network (AERONET) over an urban-industrial site, Nanjing (32.21° N, 118.72° E, and 62 m above sea level), in the Yangtze River Delta, China, during September 2007-August 2008. The annual averaged values of aerosol optical depth (AOD500) and the Ångström exponent (AE440-870) were measured to be 0.94 ± 0.52 and 1.10 ± 0.21, respectively. The seasonal averaged values of AOD500 (AE440-870) were noticed to be high in summer (autumn) and low in autumn (spring). The characterization of aerosol types showed the dominance of mixed type followed by the biomass burning and urban-industrial type of aerosol at Nanjing. Subsequently, the curvature (a 2) obtained from the second-order polynomial fit and the second derivative of AE (α') were also analyzed to understand the dominant aerosol type. The single scattering albedo at 440 nm (SSA440) varied from 0.88 to 0.93 with relatively lower (higher) values during the summer (spring), suggesting an increase in black carbon and mineral dust (desert dust) aerosols of absorbing (scattering) nature. The averaged monthly and seasonal evolutions of shortwave (0.3-4.0 μm) direct aerosol radiative forcing (DARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and bottom of atmosphere (SUR) during the study period. Further, the aerosol forcing efficiency (AFE) and the corresponding atmospheric heating rates (AHR) were also estimated from the forcing within the atmosphere (ATM). The derived DARF values, therefore, produced a warming effect within the atmosphere due to strong absorption of solar radiation.

  1. A Self-Sustained Wireless Multi-Sensor Platform Integrated with Printable Organic Sensors for Indoor Environmental Monitoring.

    Science.gov (United States)

    Wu, Chun-Chang; Chuang, Wen-Yu; Wu, Ching-Da; Su, Yu-Cheng; Huang, Yung-Yang; Huang, Yang-Jing; Peng, Sheng-Yu; Yu, Shih-An; Lin, Chih-Ting; Lu, Shey-Shi

    2017-03-29

    A self-sustained multi-sensor platform for indoor environmental monitoring is proposed in this paper. To reduce the cost and power consumption of the sensing platform, in the developed platform, organic materials of PEDOT:PSS and PEDOT:PSS/EB-PANI are used as the sensing films for humidity and CO₂ detection, respectively. Different from traditional gas sensors, these organic sensing films can operate at room temperature without heating processes or infrared transceivers so that the power consumption of the developed humidity and the CO₂ sensors can be as low as 10 μW and 5 μW, respectively. To cooperate with these low-power sensors, a Complementary Metal-Oxide-Semiconductor (CMOS) system-on-chip (SoC) is designed to amplify and to read out multiple sensor signals with low power consumption. The developed SoC includes an analog-front-end interface circuit (AFE), an analog-to-digital convertor (ADC), a digital controller and a power management unit (PMU). Scheduled by the digital controller, the sensing circuits are power gated with a small duty-cycle to reduce the average power consumption to 3.2 μW. The designed PMU converts the power scavenged from a dye sensitized solar cell (DSSC) module into required supply voltages for SoC circuits operation under typical indoor illuminance conditions. To our knowledge, this is the first multiple environmental parameters (Temperature/CO₂/Humidity) sensing platform that demonstrates a true self-powering functionality for long-term operations.

  2. A configurable electronics system for the ESS-Bilbao beam position monitors

    Energy Technology Data Exchange (ETDEWEB)

    Muguira, L., E-mail: lmuguira@essbilbao.org [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain); Belver, D. [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain); Etxebarria, V. [University of Basque Country (UPV/EHU), Department of Electricity and Electronics, Science and Technology Faculty, 48940 Leioa (Bizkaia) (Spain); Varnasseri, S.; Arredondo, I.; Campo, M. del; Echevarria, P.; Garmendia, N.; Feuchtwanger, J. [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain); Jugo, J.; Portilla, J. [University of Basque Country (UPV/EHU), Department of Electricity and Electronics, Science and Technology Faculty, 48940 Leioa (Bizkaia) (Spain)

    2013-09-01

    A versatile and configurable system has been developed in order to monitorize the beam position and to meet all the requirements of the future ESS-Bilbao Linac. At the same time the design has been conceived to be open and configurable so that it could eventually be used in different kinds of accelerators, independent of the charged particle, with minimal change. The design of the Beam Position Monitors (BPMs) system includes a test bench both for button-type pick-ups (PU) and striplines (SL), the electronic units and the control system. The electronic units consist of two main parts. The first part is an Analog Front-End (AFE) unit where the RF signals are filtered, conditioned and converted to base-band. The second part is a Digital Front-End (DFE) unit which is based on an FPGA board where the base-band signals are sampled in order to calculate the beam position, the amplitude and the phase. To manage the system a Multipurpose Controller (MC) developed at ESSB has been used. It includes the FPGA management, the EPICS integration and Archiver Instances. A description of the system and a comparison between the performance of both PU and SL BPM designs measured with this electronics system are fully described and discussed. -- Author-Highlights: • A versatile and configurable BPM system for the ESS-Bilbao Linac has been designed. • The design works for PU and SL detectors, both in continuous and pulsed wave modes. • Several tests at simulated beamlines at 352 MHz and 175 MHz have been performed. • The BPM system has been integrated in EPICS and Archiver.

  3. [Validity and Reliability of the Attitudes Toward Sexuality in the Elderly Questionnaire in Cartagena, Colombia].

    Science.gov (United States)

    Melguizo-Herrera, Estela; Álvarez-Romero, Yuleysi; Cabarcas-Mendoza, Mayerlin Vanessa; Calvo-Rodríguez, Rossy Stefanie; Flórez-Almanza, Jeomaidis; Moadie-Contreras, Olga Patricia; Campo-Arias, Adalberto

    2015-01-01

    There are many stereotypes and prejudices about the sexual lives of the elderly. However, there are no validated and reliable tools for measuring these in the Latin-American context. To determine the internal consistency, dimensionality, differential item functioning (DIF) by gender and stability of the Attitudes towards Sexuality in the Elderly Questionnaire (ASEQ) in adults over 60 years-old in Cartagena, Colombia. A validation study was designed that included a sample of 130 participants without cognitive impairment attending a Life Center. The ages ranged between 60 and 90 years (mean, 73.7±8.0), and there were 61.5% females. Internal consistency was calculated using Cronbach alpha and McDonald omega, exploratory factor analysis (EFA) (dimensionality), DIF by gender (item response theory) with Kendall correlation, and stability (reproducibility) with Pearson correlation and intraclass correlation coefficient (ICC). The ASEQ showed high internal consistency on the first application (α=.83 and ω=.87) and in the second one (α=.85 and ω=.89). AFE showed two salient factors (prejudices and limitations) that explained 42.6% of the total variance. The IDF presented appropriate coefficients, with the exception of item 14 that showed a high value (τ=.37). ASEQ showed high stability (r=.82 and ICC=.89; 95% confidence interval, 0.83- 0.92; P<.001). ASEQ is a two-dimensional and reliable scale in older adults attending a Life Center in Cartagena, Colombia. New studies are required to evaluate the performance in a representative sample. Copyright © 2014 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  4. A comparative study of the physicochemical properties and antimicrobial qualities of Abuad moringa soap with conventional medicated soaps

    Directory of Open Access Journals (Sweden)

    Pius Abimbola Okiki

    2017-01-01

    Full Text Available The study was aimed at assessing the physicochemical properties and antimicrobial qualities of 'ABUAD moringa soap', a herbal soap produced with Moringa oleifera leaf by 'ABUAD Farm', Afe Babalola University, Ado Ekiti, Nigeria. The physicochemical properties and antimicrobial qualities of  ABUAD moringa soap on some selected bacteria and fungi were evaluated and compared with those of some conventional medicated and herbal soaps commonly used in Nigeria, such as Dettol,  Tetmosol, Tura, Septol, Delta and Dudu Osun (herbal, as well as Lux, which serves as a control soap. The results of the physicochemical analyses revealed that all the soaps fall within the pH range of 8.83 and 9.83. All the soaps possess low values of free caustic alkali and detectable free fatty acid, as well as moderate values of total fatty matter. In-vitro antibacterial and antifungal activities of the soaps were investigated against microbial agents commonly found in association with skin infections, using the well-agar diffusion technique. The bacteria tested were Staphylococcus aureus ATCC 25923 and Proteus mirabilis (ATCC 12453, as well as four clinical isolates namely, Escherichia coli, Leutococcus sanguinis, Corynebacterium accolens and Burkholderia cepacia. The fungi were Candida albicans ATCC 10231, Malassezia furfur ATCC 44349, and Cryptococcus neoformans ATCC 23645. All the soaps, with exeption of lux, produced varied degrees of antibacterial activities, but ABUAD Moringa soap and Dudu Osun indicated superior effectiveness against the bacteria tested. Antifugal activities were produced by ABUAD moringa and Dudu Osun soaps only, on the fungi tested.  ABUAD Moringa produced significantly higher antifungal activities on Malassezia furfur ATCC 44349 and Candida albicans ATCC 10231 than Dudu Osun, but no significant difference was observed between the two soaps on their activities against Cryptococcus neoformans ATCC 23645. The study showed that ABUAD Moringa soap

  5. Herbal Medicines for Leucorrhea According to Iranian Traditional Medicine.

    Science.gov (United States)

    Dehdari, Sahar; Hajimehdipoor, Homa

    2016-05-01

    Leucorrhea or vaginal discharge is a conventional complaint. It is generally whitish, yellowish, or greenish vaginal discharge in females that might be normal or a symptom of infection. It is almost mucus discharge, which exhibit exfoliation of vaginal epithelial cells due to estrogen influence on the vaginal mucosa. It is important to identify the differences between physiologic and pathologic discharges. Leucorrhea is a well-known disease in Iranian traditional medicine (ITM). In their manuscripts, the word "Sayalan-e rahem" was used by Avicenna and some other Iranian traditional practitioners to describe this condition. Ancient practitioners believed that excessive residue (kesrate fozool) and weakness of digestion (Za'afe hazm) were the main causes of leucorrhea, for which herbal therapy was the main proposed treatment. In the present study, medicinal plants used in ITM for leucorrhea are introduced. In this research, six Iranian traditional textbooks including Canon of Medicine (Avicena 980-1037 AD), A-Hawi (Razes 865-925 AD), Tuhfat ul-Momineen (Mo'men tonekaboni, 17th century), Makhzan-ul-Adwiah (Aghili 18th century), Ikhtiarat Badi'i (Ansari 1329-1404 AD), and al-jāmi li-mufradāt al-adwiyawa al-aghdhiy (Ibn al-Baitar 1197 AD) were studied and searched for anti-leucorrhea medicines. Then the herbal medicines were selected and scored depending on their frequency in the above-mentioned textbooks. Additional attention was paid to provide the most suitable scientific name for each plant. This study introduced many Materia Medica with anti-leucorrhea activity and among them seven herbs including Rubus fruticosus L., Rhus coriaria L., Phoenix dactylifera L., Pimpinella anisum L., Rumex acetosa L., Olea europaea L. and Quercus lusitanica Lam. showed the most repetition in ITM prescriptions. These herbs can be introduced as new anti-leucorrhea herbal medicines for clinical research.

  6. Local time dependence of the thermal structure in the Venusian equatorial region revealed by Akatsuki radio occultation measurements

    Science.gov (United States)

    Ando, H.; Fukuhara, T.; Takagi, M.; Imamura, T.; Sugimoto, N.; Sagawa, H.

    2017-12-01

    The radio occultation technique is one of the most useful methods to retrieve vertical temperature profiles in planetary atmospheres. Ultra-Stable Oscillator (USO) onboard Venus Climate Orbiter, Akatsuki, enables us to investigate the thermal structure of the Venus atmosphere between about 40-90 km levels. It is expected that 35 temperature profiles will be obtained by the radio occultation measurements of Akatsuki until August 2017. Static stability derived from the temperature profiles shows its local time dependence above the cloud top level at low-latitudes equatorward of 25˚. The vertical profiles of the static stability in the dawn and dusk regions have maxima at 77 km and 82 km levels, respectively. A general circulation model (GCM) for the Venus atmosphere (AFES-Venus) reproduced the thermal structures above the cloud top qualitatively consistent with the radio occultation measurements; the maxima of the static stability are seen both in the dawn and dusk regions, and the local maximum of the static stability in the dusk region is located at a highler level than in the dawn region. Comparing the thermal structures between the radio occultation measurements and the GCM results, it is suggested that the distribution of the static stability above the cloud top could be strongly affected by the diurnal tide. The thermal tide influences on the thermal structure as well as atmospheric motions above the cloud level. In addition, it is shown that zonally averaged zonal wind at about 80 km altitude could be roughly estimated from the radio occultation measurements using the dispersion relation of the internal gravity wave.

  7. Portable bioimpedance monitor evaluation for continuous impedance measurements. Towards wearable plethysmography applications.

    Science.gov (United States)

    Ferreira, J; Seoane, F; Lindecrantz, K

    2013-01-01

    Personalised Health Systems (PHS) that could benefit the life quality of the patients as well as decreasing the health care costs for society among other factors are arisen. The purpose of this paper is to study the capabilities of the System-on-Chip Impedance Network Analyser AD5933 performing high speed single frequency continuous bioimpedance measurements. From a theoretical analysis, the minimum continuous impedance estimation time was determined, and the AD5933 with a custom 4-Electrode Analog Front-End (AFE) was used to experimentally determine the maximum continuous impedance estimation frequency as well as the system impedance estimation error when measuring a 2R1C electrical circuit model. Transthoracic Electrical Bioimpedance (TEB) measurements in a healthy subject were obtained using 3M gel electrodes in a tetrapolar lateral spot electrode configuration. The obtained TEB raw signal was filtered in MATLAB to obtain the respiration and cardiogenic signals, and from the cardiogenic signal the impedance derivative signal (dZ/dt) was also calculated. The results have shown that the maximum continuous impedance estimation rate was approximately 550 measurements per second with a magnitude estimation error below 1% on 2R1C-parallel bridge measurements. The displayed respiration and cardiac signals exhibited good performance, and they could be used to obtain valuable information in some plethysmography monitoring applications. The obtained results suggest that the AD5933-based monitor could be used for the implementation of a portable and wearable Bioimpedance plethysmograph that could be used in applications such as Impedance Cardiography. These results combined with the research done in functional garments and textile electrodes might enable the implementation of PHS applications in a relatively short time from now.

  8. Efeitos da gameterapia na mielorradiculopatia esquistossomótica: Relato de caso

    Directory of Open Access Journals (Sweden)

    Tiago Pinheiro Vaz Carvalho

    2014-06-01

    Full Text Available A esquistossomose mansônica é uma doença parasitária causada pelo helminto Schistosoma mansoni. A sua forma ectópica mais grave e incapacitante é a mielorradiculopatia esquistossomótica (MRE, caracterizada por atingir o sistema nervoso central. Atualmente, o uso da Realidade Virtual para o tratamento das sequelas de doenças neurológicas vem se desenvolvendo gradativamente. O objetivo deste estudo foi analisar a influência da Realidade Virtual (RV sobre as funções neuromotoras de uma portadora de MRE. O estudo foi realizado com um indivíduo do sexo feminino, 30 anos de idade, com diagnóstico clínico de MRE e sem experiência prévia com o Nintendo Wii® ou similares. O procedimento de avaliação adotado visou à descrição e análise do comprometimento causado pelas afeções da MRE. A paciente foi avaliada, submetida à fisioterapia utilizando o Nintendo Wii® e a plataforma Wii Balance Board® que consistiu de 20 sessões com duração de 1 hora e frequência de três vezes por semana; após o tratamento a paciente foi reavaliada. Os resultados demonstraram que para a voluntária em estudo, a RV foi uma ferramenta eficaz na reabilitação neuromotora de MRE.

  9. Effect of diet on brain metabolites and behavior in spontaneously hypertensive rats.

    Science.gov (United States)

    Liso Navarro, Ana A; Sikoglu, Elif M; Heinze, Cailin R; Rogan, Ryan C; Russell, Vivienne A; King, Jean A; Moore, Constance M

    2014-08-15

    Attention-deficit hyperactivity disorder (ADHD) is a heterogeneous psychiatric disorder affecting 5-10% of children. One of the suggested mechanisms underlying the pathophysiology of ADHD is insufficient energy supply to neurons. Here, we investigated the role of omega 3 fatty acids in altering neural energy metabolism and behavior of spontaneously hypertensive rats (SHR), which is an animal model of ADHD. To this end, we employed Proton Magnetic Resonance Spectroscopy ((1)H MRS) to evaluate changes in brain neurochemistry in the SHR following consumption of one of three experimental diets (starting PND 21): fish oil enriched (FOE), regular (RD) and animal fat enriched (AFE) diet. Behavioral tests were performed to evaluate differences in locomotor activity and risk-taking behavior (starting PND 44). Comparison of frontal lobe metabolites showed that increased amounts of omega 3 fatty acids decreased total Creatine levels (tCr), but did not change Glutamate (Glu), total N-Acetylaspartate (tNAA), Lactate (Lac), Choline (Cho) or Inositol (Ino) levels. Although behavior was not significantly affected by different diets, significant correlations were observed between brain metabolites and behavior in the open field and elevated plus maze. SHR with higher levels of brain tCr and Glu exhibited greater hyperactivity in a familiar environment. On the other hand, risk-taking exploration of the elevated plus maze's open arms correlated negatively with forebrain tNAA and Lac levels. These findings support the possible alteration in energy metabolites in ADHD, correlating with hyperactivity in the animal model. The data also suggest that omega 3 fatty acids alter brain energy and phospholipid metabolism. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. The predisposing factors for the heterotopic ossification after cervical artificial disc replacement.

    Science.gov (United States)

    Yi, Seong; Shin, Dong Ah; Kim, Keung Nyun; Choi, Gwihyun; Shin, Hyun Chul; Kim, Keun Su; Yoon, Do Heum

    2013-09-01

    Heterotopic ossification (HO) is defined as a formation of bone outside the skeletal system. The reported HO occurrence rate in cervical artificial disc replacement (ADR) is unexpectedly high and is known to vary. However, the predisposing factors for HO in cervical ADR have not yet been elucidated. Investigation of the predisposing factors of HO in cervical arthroplasty and the relationship between degeneration of the cervical spine and HO occurrence. Retrospective study to discover predisposing factors of HO in cervical arthroplasty. A total of 170 patients who underwent cervical ADR were enrolled including full follow-up clinical and radiologic data. Radiologic outcomes were assessed by identification of HOs according to McAfee's classifications. This study enrolled a total of 170 patients who underwent cervical ADR. Pre-existing degenerative change included anterior or posterior osteophytes, ossification of the anterior longitudinal ligament, posterior longitudinal ligament, or ligamentum nuchae. The relationships between basic patient data, pre-existing degenerative change, and HO were investigated using linear logistic regression analysis. Among all 170 patients, HO was found in 69 patients (40.6%). Among the postulated predisposing factors, only male gender and artificial disc device type were shown to be statistically significant. Unexpectedly, preoperative degenerative changes in the cervical spine exerted no significant influence on the occurrence of HOs. The odds ratio of male gender compared with female gender was 2.117. With regard to device type, the odds ratios of Mobi-C (LDR medical, Troyes, France) and ProDisc-C (Synthes, Inc., West Chester, PA, USA) were 5.262 and 7.449, respectively, compared with the Bryan disc. Definite differences in occurrence rate according to the gender of patients and the prosthesis type were identified in this study. Moreover, factors indefinably expected to influence HO in the past were not shown to be risk factors

  11. Analysis of emotion regulation in Spanish adolescents: Validation of the Emotion Regulation Questionnaire

    Directory of Open Access Journals (Sweden)

    Olga eGómez-Ortiz

    2016-01-01

    Full Text Available Emotion regulation (ER is a basic psychological process that has been broadly linked to psychosocial adjustment. Due to its relationship with psychosocial adjustment, a significant number of instruments have been developed to assess emotion regulation in a reliable and valid manner. Among these, the Emotion Regulation Questionnaire (ERQ; Gross & John, 2003 is one of the most widely used, having shown good psychometric properties with adult samples from different cultures. Studies of validation in children and adolescents are, however, scarce and have only been developed for the Australian and Portuguese populations. The aim of this study was to validate the Spanish version of the ERQ for use in adolescents and determine possible differences according to the gender and age of young people. The sample consisted of 2060 adolescents (52.1% boys. Exploratory and Confirmatory factor analysis (EFA and CFA, multi-group analysis and two-way multivariate analysis of variance (MANOVA were performed and the percentiles calculated. The results of the AFE and CFA corroborated the existence of two factors related to the emotion regulation strategies of cognitive reappraisal and expressive suppression, showing acceptable internal consistency and test-retest reliability. Both factors also showed good criterion validity with personality traits, self-esteem, and social anxiety. Differences in cognitive reappraisal were found with regard to age, with younger students exhibiting the greatest mastery of this strategy. Gender differences were observed regarding the expressive suppression strategy, with boys being more likely to use this strategy than girls. A gender-age interaction effect was also observed, revealing that the use of the expressive suppression strategy did not vary by age in girls, and was more widely used by boys aged 12-14 years than those aged 15-16 years. However, we found evidence of measurement invariance across sex and age groups. The results

  12. Modeling and analysis of the spectrum of the globular cluster NGC 2419

    Science.gov (United States)

    Sharina, M. E.; Shimansky, V. V.; Davoust, E.

    2013-06-01

    The properties of the stellar population of the unusual object NGC 2419 are studied; this is the most distant high-mass globular cluster of the Galaxy's outer halo, and a spectrum taken with the 1.93-m telescope of the Haute Provence Observatory displays elemental abundance anomalies. Since traditional high-resolution spectroscopicmethods are applicable to bright stars only, spectroscopic information for the cluster's stellar population as a whole, integrated along the spectrograph slit placed in various positions, is used. Population synthesis is carried out for the spectrum of NGC 2419 using synthetic spectra calculated from a grid of stellar model atmospheres, based on the theoretical isochrone from the literature that best fits the color-magnitude diagram of the cluster. The derived age (12.6 billion years), metallicity ([Fe/H] = -2.25 dex), and abundances of helium ( Y = 0.26) and other chemical elements (a total of 14) are in a good qualitative agreement with estimates from the literature made from high-resolution spectra of eight red giants in the cluster. The influence on the spectrum of deviations from local thermodynamic equilibrium is considered for several elements. The derived abundance of α-elements ([ α/Fe] = 0.13 dex, as the mean of [O/Fe], [Mg/Fe], and [Ca/Fe]) differs from the mean value in the literature ([ α/Fe] = 0.4 for the eight brightest red giants) and may be explained by recently discovered in NGC2419 large [a/Fe] dispersion. Further studies of the integrated properties of the stellar population in NGC 2419 using higher-resolution spectrographs in various wavelength ranges should help improve our understanding of the cluster's chemical anomalies.

  13. A low-power and miniaturized electrocardiograph data collection system with smart textile electrodes for monitoring of cardiac function.

    Science.gov (United States)

    Dai, Ming; Xiao, Xueliang; Chen, Xin; Lin, Haoming; Wu, Wanqing; Chen, Siping

    2016-12-01

    With the increasing aging population as well as health concerns, chronic heart disease has become the focus of public attention. A comfortable, low-powered, and wearable electrocardiogram (ECG) system for continuously monitoring the elderly's ECG signals over several hours is important for preventing cardiovascular diseases. Traditional ECG monitoring apparatus is often inconvenient to carry, has many electrodes to attach to the chest, and has a high-power consumption. There is also a challenge to design an electrocardiograph that satisfies requirements such as comfort, confinement, and compactness. Based on these considerations, this study presents a biosensor acquisition system for wearable, ubiquitous healthcare applications using three textile electrodes and a recording circuit specialized for ECG monitoring. In addition, several methods were adopted to reduce the power consumption of the device. The proposed system is composed of three parts: (1) an ECG analog front end (AFE), (2) digital signal processing and micro-control circuits, and (3) system software. Digital filter methods were used to eliminate the baseline wander, skin contact noise, and other interfering signals. A comparative study was conducted using this system to observe its performance with two commercial Holter monitors. The experimental results demonstrated that the total power consumption of this proposed system in a full round of ECG acquisition was only 29.74 mW. In addition, this low-power system performed well and stably measured the heart rate with an accuracy of 98.55 %. It can also contain a real-time dynamic display with organic light-emitting diodes (OLED) and wirelessly transmit information via a Bluetooth 4.0 module.

  14. El análisis de necesidades formativas en organizaciones a través del paradigma de la Ciencia Pragmática

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    ANTONIO SOTO BERENGUEL

    2003-01-01

    Full Text Available El presente trabajo documenta una investigación aplicada cuyo objetivo principal es analizar las necesidades e intereses formativos que la plantilla de una entidad financiera empíricamente manifiesta, como forma de obtener feedback inductivo (upward que permita diseñar más rigurosamente los planes de formación. Para ello se realizó un análisis de contenido de la oferta formativa existente en el mercado, a partir del cual se diseñó un cuestionario de 24 ítems que recogen una serie de contenidos formativos propios del sector financiero. Tras lanzarlo a la red de oficinas para su cumplimentación, se recibieron un total de 511 cuestionarios completos realizados por directores, interventores y administrativos de oficinas de la entidad. Se mecanizaron informáticamente los datos en soporte SPSS 9.0 y se trataron estadísticamente. En primer lugar se sometieron a Análisis Factorial Exploratorio (AFE-CP y los resultados revelan la existencia de cuatro factores o áreas formativas clave, cuyas demandas por parte de los empleados difieren significativamente en función de varios aspectos o variables independientes. También hemos podido comprobar que existen diferencias en cuanto a la representatividad y peso específico de cada uno de los contenidos de cada factor para abarcar el dominio específico que a priori pretendían cubrir. A partir de estos resultados se formularon una serie de pautas que afectan directamente al diseño del plan de formación anual de la entidad, tales como establecer prioridades y reestructurar los contenidos formativos para cada área.

  15. Stripper, shut-in and orphan wells in joint operations

    International Nuclear Information System (INIS)

    Nixon, R.

    1999-01-01

    Low productivity wells, stripper wells, can be an excellent source of income to independent operators or small companies, but a serious financial burden for larger companies. Shut-in wells, for most companies, are either waiting on a market and production facilities, or represent deferred abandonment liabilities. Orphan wells also reflect financial distress. The firm, Cord Oil and Gas Management Ltd., was formed in 1986 to specifically assist oil and gas companies, sophisticated investors and financial institutions with the management, enhancement and disposition of non-core or low productivity assets. This type of production, depending on the number of wells and cumulative production, can be the life blood of a small organization or a serious drain on the administrative personnel and financial resources of larger organizations. Philosophically, industry and/or government needs to manage the eventuality of abandonments by establishing financial criteria. Some suggestions for industry include: (1) establish provisions within joint operating agreements to set aside an abandonment and environmental cleanup fund; (2) minimize the inventory of abandonment candidates by an ongoing program of reclamation; (3) offset abandonment costs with salvage value of tangible equipment under AFE approval; and (4) voluntarily restrict transfer abandonment liabilities with producing assets on a selective basis. Some suggestions for governments include: (1) fund the orphan well by a deposit for every well drilled; (2) restrict the transfer of liabilities for abandoned and inactive wells by ensuring that the transferee is financially capable; and (3) access the chain of title to ensure non-operators remain responsible for the proportionate shares of abandonment and cleanup costs

  16. Molecular dynamics simulations of proton-ordered water confined in low-diameter carbon nanotubes.

    Science.gov (United States)

    Li, Shujuan; Schmidt, Burkhard

    2015-03-21

    The present work deals with molecular dynamics simulations of water confined in single-walled carbon nanotubes (CNTs), with emphasis on the proton-ordering of water and its polarization. First, the water occupancy of open-ended armchair and zigzag CNTs immersed in water under ambient NPT conditions is calculated for various water models, and for varying Lennard-Jones parameters of the water-carbon interaction. As a function of the CNT diameter, the water density displays several oscillations before converging to the bulk value. Based on these results, the water structures encapsulated in 10 nm long armchair CNTs (n,n) with 5 ≤ n ≤ 10, are investigated under NVT conditions. Inside the smallest nanotubes (n = 5, 6) highly ferroelectric (FE), quasi-one-dimensional water chains are found while inside the other CNTs water molecules assemble into single-walled ice nanotubes (INTs). There are several, near-degenerate minimum energy INT structures: single helical structures were found for 7 ≤ n ≤ 10, in all cases in FE arrangement. In addition, a double helical INT structure was found for n = 8 with an even higher polarization. Prism-like structures were found only for 8 ≤ n ≤ 10 with various FE, ferrielectric (FI), and antiferroelectric (AF, n = 9, 10) proton ordering. The coexistence of the nearly iso-energetic FE, FI, and AF INT structures separated by high barriers renders the molecular dynamics highly metastable, typically with nanosecond timescales at room temperature. Hence, the replica exchange simulation method is used to obtain populations of different INT states at finite temperatures. Many of the FE INT structures confined in low-diameter CNTs are still prevalent at room temperature. Both helix-helix and helix-prism structural transitions are detected which can be either continuous (around 470 K for n = 8) or discontinuous (at 218 K for n = 9). Also melting-like transitions are found in which the INT structures are disrupted leading to a loss of FE

  17. Synthesis and properties of ternary (K, NH4, H3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

    International Nuclear Information System (INIS)

    Sandy Jones, F.; Bigham, Jerry M.; Gramp, Jonathan P.; Tuovinen, Olli H.

    2014-01-01

    The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K + (0, 1, 4, 6, 12, 31 mM) and NH 4 + (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO 4 solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe 3 (SO 4 ) 2 (OH) 6 ) and/or schwertmannite (idealized formula Fe 8 O 8 (OH) 6 (SO 4 )·nH 2 O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K + (≤ 4 mM) and NH 4 + (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K + and NH 4 + are similar, K + greatly facilitated the formation of a jarosite phase compared to NH 4 + . Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH 4 , H 3 O)-solid solutions that were also deficient in structural Fe, especially at low NH 4 contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K + and NH 4 + in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH 4 -jarosite were detected in the un-aged precipitates. - Highlights: • Fe(III) precipitates formed in A. ferrooxidans culture solutions were characterized. • The monovalent cation

  18. Diferentes níveis de cálcio e o desenvolvimento de plantas de estilosantes (Stylosanthes guyanensis (Aubl. Sw. cv "Cook" Growth of stylo plants as affected by calcium levels (Stylosanthes guyanensis (Aubl. Sw. cv "Cook"

    Directory of Open Access Journals (Sweden)

    J.D. Rodrigues

    1993-09-01

    Full Text Available O presente experimento teve como finalidade estudar os efeitos de níveis de cálcio no desenvolvimento de plantas de Stylosanthes guyanensis (Aubl. Sw. cv "Cook", em sua fase vegetativa, através dos parâmetros que compõem a análise fisiológica de crescimento e de que forma estes parâmetros se alteram, em função dos tratamentos utilizados. Delinearam-se quatro tratamentos, a saber: T1 (200 mg de cálcio/litro; T2 (133,33 mg de cálcio/litro; T3 (66,66 mg de cálcio/litro; T4 (omisso em cálcio. O experimento foi instalado em cultivo hidropônico, empregando-se solução nutritiva n° 1 de Hoagland & Arnon (1950 e conduzido em casa de vegetação. O experimento, inteiramente casualizado, obedeceu ao delineamento de parcelas sub-divididas, considerando-se as cinco coletas, realizadas a intervalos de 14 dias como parcelas, sendo os tratamentos empregados definidos como sub-parcelas. A influência dos diferentes tratamentos, foi avaliada através da área foliar (AF, área foliar específica (AFE, razão de massa foliar (RMF e razão de área foliar (RAF. Dos resultados obtidos, pôde-se concluir que plantas de estilosantes, durante a fase de crescimento vegetativo, alcançaram melhor desenvolvimento em níveis de 200 mg de cálcio/litro de solução nutritiva.The influence of calcium levels on the growth of Stylosanthes guyanensis (Aubl. SW. c v "Cook" plants was studied under the following treatments: T1 (200 mg of calcium/litre; T2 (133.33 mg of calcium/litre; T3 (66.66 mg of calcium/litre and T4 (without calcium. The study was carried out in a hydroponic media with Hoagland & Arnon's number one nutrient solution. The experiment was designed as a completely randomized split-plot design, considering the five samplings performed in 14 day intervals as main plots. The influence of different treatments was evaluated through leaf area (LA, specific leaf area (SLA, leaf weight ratio (LWR, and leaf area ratio (LAR. The results obtained indicated

  19. Habilidade competitiva de plantas de arroz com biótipos de capim-arroz resistente ou suscetível ao quinclorac Competitive ability of rice plants with barnyardgrass biotypes resistant or susceptible to quinclorac

    Directory of Open Access Journals (Sweden)

    S.P. Tironi

    2009-06-01

    Full Text Available Objetivou-se com este trabalho avaliar a habilidade competitiva de plantas de arroz cultivar BRS Pelota com biótipos de capim-arroz resistente ou suscetível ao herbicida quinclorac. Para isso, foi instalado experimento em casa de vegetação, em delineamento completamente casualizado com quatro repetições, sendo os tratamentos dispostos em esquema fatorial 2 x 6. As unidades experimentais constaram de vasos plásticos contendo 10 dm³ de solo, cujo pH e nível de nutrientes foram previamente corrigidos. Os tratamentos consistiram na competição entre uma planta de arroz, cultivar BRS Pelota, com populações (0, 1, 2, 3, 4 ou 5 plantas por vaso dos biótipos de capim-arroz resistente (ECH-13 ou suscetível (ECH-12 ao herbicida quinclorac. As avaliações foram realizadas aos 40 dias após emergência, sendo avaliados; massa seca da parte aérea (MSPA, taxa de crescimento (TC, área foliar específica (AFE, razão de massa foliar (RMF, razão de área foliar (RAF e índice de área foliar (IAF. A interferência no desenvolvimento do cultivar de arroz BRS Pelota foi proporcionalmente maior com o aumento da população de ambos os biótipos de capim-arroz. Os biótipos apresentaram, em geral, habilidade competitiva similar.The objective of this study was to evaluate the competitive ability of the rice cultivar BRS Pelota with biotypes resistant or susceptible to the herbicide Quinclorac. The experiment was conducted under greenhouse conditions in a completely randomized design with four replications, with the treatments arranged in a 2 x 6 factorial. The experimental units consisted of plastic pots containing 10 dm³ of soil, with pH and nutrient level being previously corrected. The treatments consisted of a competition between a rice plant, BRS Pelota cultivar, with populations (0, 1, 2, 3, 4 or 5 plants per pot of the barnyardgrass biotypes resistant (ECH-13 or susceptible (ECH -12 to the herbicide Quinclorac. The evaluations were performed

  20. Molecular Computational Investigation of Electron Transfer Kinetics across Cytochrome-Iron Oxide Interfaces

    International Nuclear Information System (INIS)

    Kerisit, Sebastien N.; Rosso, Kevin M.; Dupuis, Michel; Valiev, Marat

    2007-01-01

    The interface between electron transfer proteins such as cytochromes and solid phase mineral oxides is central to the activity of dissimilatory-metal reducing bacteria. A combination of potential-based molecular dynamics simulations and ab initio electronic structure calculations are used in the framework of Marcus' electron transfer theory to compute elementary electron transfer rates from a well-defined cytochrome model, namely the small tetraheme cytochrome (STC) from Shewanella oneidensis, to surfaces of the iron oxide mineral hematite (a-Fe2O3). Room temperature molecular dynamics simulations show that an isolated STC molecule favors surface attachment via direct contact of hemes I and IV at the poles of the elongated axis, with electron transfer distances as small as 9 Angstroms. The cytochrome remains attached to the mineral surface in the presence of water and shows limited surface diffusion at the interface. Ab initio electronic coupling matrix element (VAB) calculations of configurations excised from the molecular dynamics simulations reveal VAB values ranging from 1 to 20 cm-1, consistent with nonadiabaticity. Using these results, together with experimental data on the redox potential of hematite and hemes in relevant cytochromes and calculations of the reorganization energy from cluster models, we estimate the rate of electron transfer across this model interface to range from 1 to 1000 s-1 for the most exothermic driving force considered in this work, and from 0.01 to 20 s-1 for the most endothermic. This fairly large range of electron transfer rates highlights the sensitivity of the rate upon the electronic coupling matrix element, which is in turn dependent on the fluctuations of the heme configuration at the interface. We characterize this dependence using an idealized bis-imidazole heme to compute from first principles the VAB variation due to porphyrin ring orientation, electron transfer distance, and mineral surface termination. The electronic

  1. A Formação da Percepção de Valor para Pequenos e Médios Consumidores B2B

    Directory of Open Access Journals (Sweden)

    Clarice Mara Sousa-e-Silva

    2018-04-01

    Full Text Available Objetivo:  Identificar e mensurar as relações entre constructos de qualidade-sacrifícios-experiência e valor percebido e satisfação, e a relação destes com a intenção de recompra de serviços logísticos de transporte por PMEs.Método: Partindo-se da proposição de escalas para mensurar os constructos qualidade, sacrifícios, experiência, valor percebido, satisfação e intenção de recompra, realizou-se um levantamento de dados cuja amostra foi composta por 195 PMEs. Utilizando técnicas de AFE, AFC e MEEPLS, propôs-se um modelo para mensurar a formação do valor percebido nos serviços logísticos adquiridos por PMEs.Originalidade/Relevância: A maioria das pesquisas de valor percebido no ambiente B2B tem considerado o desempenho dos bens e serviços em uma perspectiva funcional e negligenciado dimensões não-racionais. Estas dimensões (aspectos não-econômicos, subjetivos e multidimensionais, se mensuradas em conjunto com dimensões comumente encontradas nos estudos de comportamento de consumo B2B, podem oferecer novas perspectivas de conhecimento teórico-empírico.Resultados: Os sacrifícios e os custos de troca atuaram de forma não-significante no relacionamento B2B. As PMEs valorizaram aspectos ligados à qualidade e à experiência. O estudo indica que PMEs, ao elegerem como formadores do valor percebido a experiência e a qualidade, e por serem influenciadas pela satisfação para formar suas intenções de recompras, gerenciam sua cadeia de suprimentos estabelecendo relacionamentos envoltos em mais subjetividades do que se esperaria de um empresário.Contribuições teóricas/metodológicas: Proposição de um modelo teórico capaz de predizer a intenção de recompra de PMEs consumidoras de serviços logísticos, tendo como antecessor a satisfação, e desta, o valor percebido.

  2. Evidência de validade do teste de conhecimento tático processual para orientação esportiva - TCTP: OE

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    Pablo Juan GRECO

    2015-06-01

    Full Text Available Este estudo objetivou investigar a evidência de validade de conteúdo, de construto e confiabilidade do teste de conhecimento tático processual para orientação esportiva (TCTP: OE de crianças e jovens nos jogos esportivos coletivos de invasão (basquetebol, futsal e handebol. No processo de validade de conteúdo participaram como juízes 11 técnicos, sendo três de basquetebol, quatro de futsal e quatro de handebol. Nos procedimentos empíricos a amostra foi composta por um total de 570 participantes. A média de idade dos participantes do estudo foi de 10,32 ± 1,45 anos. A validade de conteúdo foi determinada pelo cálculo do coeficiente de validade de conteúdo (CVC. Utilizou-se análise fatorial exploratória (AFE para a validade de construto. O método utilizado foi o de componentes principais com rotação ortogonal Varimax e normalização Kaiser. A Confiabilidade do TCTP: OE foi estabelecida, por meio do método teste re-teste em dias diferentes. A técnica usada foi a correlação intraclasse (ICC. Em relação à validade de conteúdo o CVC calculado para clareza da linguagem (CVCt = 0,83, pertinência prática (CVCt = 0,91 e relevância teórica (CVCt = 0,95 foi satisfatório. A análise fatorial exploratória confirmou a estrutura do modelo final com dois fatores, denominados de ataque e defesa, explicando em todos os casos acima de 66% da variância. Em relação à confiabilidade do instrumento o TCTP: OE apresentou valores satisfatórios e excelentes (ICC ≥ 0,4. Conclui-se que o TCTP: OE viabiliza a avaliação do jogador seja com mão/pé, o que determina uma avaliação condizente com os atuais preceitos da iniciação esportiva.

  3. Phenotypic and molecular characteristics of methicillin-resistant Staphylococcus aureus isolates from Ekiti State, Nigeria

    Directory of Open Access Journals (Sweden)

    Olowe OA

    2013-08-01

    Full Text Available Olugbenga Adekunle Olowe,1 Olayinka Oluwatoyin Kukoyi,2 Samuel Sunday Taiwo,1 Olusola Ojurongbe,1 Oluyinka Oladele Opaleye,1 Oloyede Samuel Bolaji,1 Abiodun Adebimpe Adegoke,1 Olufunmilola Bamidele Makanjuola,1 David Olusoga Ogbolu,3 Oyebode Terry Alli31Department of Medical Microbiology and Parasitology, College of Health Sciences, Ladoke Akintola University of Technology, Ogbomoso, Nigeria; 2Department of Microbiology, College of Sciences, Afe Babalola University, Ado-Ekiti, Nigeria; 3Department of Biomedical Sciences, College of Health Sciences, Lautech, Osogbo, NigeriaIntroduction: The characteristics and antimicrobial resistance profiles of Staphylococcus aureus differs according to geographical regions and in relation to antibiotic usage. The aim of this study was to determine the biochemical characteristics of the prevalent S. aureus from Ekiti State, Nigeria, and to evaluate three commonly used disk diffusion methods (cefoxitin, oxacillin, and methicillin for the detection of methicillin resistance in comparison with mecA gene detection by polymerase chain reaction.Materials and methods: A total of 208 isolates of S. aureus recovered from clinical specimens were included in this study. Standard microbiological procedures were employed in isolating the strains. Susceptibility of each isolate to methicillin (5 µg, oxacillin (1 µg, and cefoxitin (30 µg was carried out using the modified Kirby–Bauer/Clinical and Laboratory Standard Institute disk diffusion technique. They were also tested against panels of antibiotics including vancomycin. The conventional polymerase chain reaction method was used to detect the presence of the mecA gene.Results: Phenotypic resistance to methicillin, oxacillin, and cefoxitin were 32.7%, 40.3%, and 46.5%, respectively. The mecA gene was detected in 40 isolates, giving a methicillin-resistant S. aureus (MRSA prevalence of 19.2%. The S. aureus isolates were resistant to penicillin (82.7% and tetracycline

  4. Genotypes and phenotypes of Shiga toxin-producing Escherichia coli (STEC in Abeokuta, Southwestern Nigeria

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    Olowe OA

    2014-10-01

    Full Text Available Olugbenga Adekunle Olowe,1 Bukola W Aboderin,1,2 Olayinka O Idris,3 Victor O Mabayoje,4 Oluyinka O Opaleye,1 O Catherine Adekunle,1 Rita Ayanbolade Olowe,1 Paul Akinniyi Akinduti,5 Olusola Ojurongbe1 1Department of Medical Microbiology and Parasitology, College of Health Sciences, Osogbo, Osun State, Nigeria; 2Medical Microbiology Unit, Pathology Department, Federal Medical Centre, Abeokuta, Nigeria; 3Department of Microbiology, College of Sciences, Afe Babalola University, Ado Ekiti, Nigeria; 4Department of Haematology, College of Health Sciences, Ladoke Akintola University, Osogbo, Osun State, Nigeria; 5Department of Medical Microbiology and Parasitology, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria Purpose: To characterize the prevalence of hemolytic Shiga toxin-producing Escherichia coli (STEC with a multidrug-resistant pattern in different age groups in Abeokuta, Nigeria. Methods: Nonrepetitive E. coli isolates were collected from 202 subjects with or without evidence of diarrhea. Each isolate was biochemically identified and antimicrobial susceptibility testing was performed using the disk diffusion method. A sorbitol fermentation test of all the E. coli isolates was done and the minimum inhibitory concentration of suspected STEC was measured by the standard broth microdilution method to determine antibiotic resistance. The genotypes of stx1, stx2, and hlyA were determined by polymerase chain reaction assay. Results: The majority of subjects were aged ≥40 years (41.6% and were female (61.9%. Of the 202 subjects, 86.1% had STEC isolates (P<0.05. A high rate of STEC isolates resistant to amoxicillin (90.6%, cefotaxime (77.7%, and cefuroxime (75.7% was observed. Resistance to amoxicillin, gentamicin, and cefotaxime was demonstrated with a minimum inhibitory concentration >16 µg/mL in 13.9%, 11.4%, and 10.4% of the isolates, respectively. The prevalence of stx1, stx2, and hlyA was 13.9%, 6.9%, and 2.0%, respectively; 5.5% of

  5. Synthesis and Characterization of Quaternary Metal Chalcogenide Aerogels for Gas Separation and Volatile Hydrocarbon Adsorption

    KAUST Repository

    Edhaim, Fatimah A.

    2017-11-01

    In this dissertation, the metathesis route of metal chalcogenide aerogel synthesis was expanded by conducting systematic studies between polysulfide building blocks and the 1st-row transition metal linkers. Resulting materials were screened as sorbents for selective gas separation and volatile organic compounds adsorption. They showed preferential adsorption of polarizable gases (CO2) and organic compounds (toluene). Ion exchange and heavy metal remediation properties have also been demonstrated. The effect of the presence of different counter-ion within chalcogel frameworks on the adsorption capacity of the chalcogels was studied on AFe3Zn3S17 (A= K, Na, and Rb) chalcogels. The highest adsorption capacity toward hydrocarbons and gases was observed on Rb based chalcogels. Adopting a new building block [BiTe3]3- with the 1st-row transition metal ions results in the formation of three high BET surface area chalcogels, KCrBiTe3, KZnBiTe3, and KFeBiTe3. The resulting chalcogels showed preferential adsorption of toluene vapor, and remarkable selectivity of CO2, indicating the potential future use of chalcogels in adsorption-based gas or hydrocarbon separation processes. The synthesis and characterization of the rare earth chalcogels NaYSnS4, NaGdSnS4, and NaTbSnS4 are also reported. Rare earth metal ions react with the thiostannate clusters in formamide solution forming extended polymeric networks by gelation. Obtained chalcogels have high BET surface areas, and showed notable adsorption capacity toward CO2 and toluene vapor. These chalcogels have also been engaged in the absorption of different organic molecules. The results reveal the ability of the chalcogels to distinguish among organic molecules on their electronic structures; hence, they could be used as sensors. Furthermore, the synthesis of metal chalcogenide aerogels Co0.5Sb0.33MoS4 and Co0.5Y0.33MoS4 by the sol-gel method is reported. In this system, the building blocks [MoS4]2- chelated with Co2+ and (Sb3

  6. Moessbauer spectroscopic characterization of ferrite ceramics

    International Nuclear Information System (INIS)

    Music, S.; Ristic, M.

    1999-01-01

    The principle of Moessbauer effect and the nature of hyperfine interactions were presented. The discovery of the Moessbauer effect was the basis of a new spectroscopic technique, called Moessbauer spectroscopy, which has already made important contribution to research in physics, chemistry, metallurgy, mineralogy and biochemistry. In the present work the selected ferrites such as spinel ferrite, NiFe 2 O 4 , and some rare earth orthoferrites and garnets were investigated using Moessbauer spectroscopy. X-ray powder diffraction and Fourier transform infrared spectroscopy were used as complementary techniques. The formation of NiFe 2 O 4 was monitored during the thermal decomposition of mixed salt (Ni(NO 3 ) 2 +2Fe(NO 3 ) 3 )nH 2 O. The ferritization of Ni 2+ ions was observed at 500 deg. C and after heating at 1300 deg. C the stoichiometric NiFe 2 O 4 was produced. The Moessbauer parameters obtained for NiFe 2 O 4 , d Fe = 0.36 mm s -1 and HMF = 528 kOe, can be ascribed to Fe 3+ ions in the octahedral sublattice, while parameters d Fe = 0.28 mm s -1 and HMF = 494 kOe can be ascribed to Fe 3+ ions in the tetrahedral lattice. The effect of ball-milling of NiFe 2 O 4 was monitored. The formation of oxide phases and their properties in the systems Nd 2 O 3 -Fe 2 O 3 , Sm 2 O 3 -Fe 2 O 3 , Gd 2 O 3 -Fe 2 O 3 , Eu 2 O 3 -Fe 2 O 3 and Er 2 O 3 -Fe 2 O 3 were also investigated. Quantitative distributions of oxide phases, a-Fe 2 O 3 , R 2 O 3 , R 3 Fe 5 O 12 and RFeO 3 , R = Gd or Eu, were determined for the systems xGd 2 O 3 +(1-x)Fe 2 O 3 and xEu 2 O 3 +(1-x)Fe 2 O 3 . The samples, prepared by chemical coprecipitation in the system xEu 2 O 3 +(1-x)Fe 2 O 3 , 0≤x≤1, were completely amorphous as observed by XRD, even at the relatively high temperature of the sample preparation (600 deg. C). Similar behavior was observed during the formation of Er 3 Fe 5 O 12 . Moessbauer spectroscopy indicated that this 'amorphous' phase is actually composed of very small and/or poor

  7. Construcción y validación del cuestionario G_Clinic para medir la satisfacción laboral en profesionales de enfermería de las unidades de gestión clínica

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    Ana Ma Porcel-Gálvez

    2014-01-01

    Full Text Available Fundamentos: La satisfacción laboral de los profesionales de enfermería es un factor determinante en la calidad y adaptación organizativa de los modelos de gestión clínica en el actual contexto socioeconómico. El objetivo del estudio fue construir y validar un cuestionario para conocer el nivel de satisfacción laboral de los profesionales enfermeros en las Unidades de Gestión Clínica en el Sistema Sanitario Público Andaluz. Métodos: Estudio clinimétrico y transversal, tomando como muestra a 314 profesionales de enfermería pertenecientes a los Hospitales Universitarios Virgen del Rocío y Virgen Macarena de Sevilla. Las encuestas se realizaron en 2011, entre los meses de marzo a junio. Se utilizó como base el cuestionario Font Roja adaptado a las variables de nuestra investigación. Se realizó el análisis de correlaciones, fiabilidad, validez de constructo mediante Análisis Factorial Exploratorio (AFE y Análisis Factorial Confirmatorio (AFC para comprobar el modelo apriorístico. Resultados: Se construyó un cuestionario con 10 ítems, cuya consistencia interna es de 0,75 con un porcentaje explicativo de la varianza del 63,67%. El AFC corroboró 4 dimensiones (clima laboral, relaciones laborales, motivación y reconocimiento: χ2 significativo (p<,001; χ2/gl=2,013; GFI=0,958, RMR=0,055 y RMSEA=0,057; AGFI=0,927, NFI=0,878, TLI=0,902, CFI=0,933 e IFI=0,935; AIC=132,486 y ECVI=0,423. Conclusiones: Este nuevo cuestionario (G_Clinic mejora los valores del cuestionario Font Roja, ya que disminuye el número de ítems, mejora la fiabilidad de cada una de las dimensiones, aumenta el valor de la varianza explicada y posibilita conocer la satisfacción de los profesionales de enfermería en la gestión clínica.

  8. An X-ray absorption spectroscopic study of the metal site preference in Al1−xGaxFeO3

    International Nuclear Information System (INIS)

    Walker, James D.S.; Grosvenor, Andrew P.

    2013-01-01

    Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO 3 (Pna2 1 ; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al 1−x Ga x FeO 3 was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L 2,3 -, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al 1−x Ga x FeO 3 indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO 3 than in GaFeO 3 , implying more anti-site disorder is present in AlFeO 3 . - Graphical abstract: Al 1−x Ga x FeO 3 has been investigated by XANES. Through examination of Al L 2,3 -, Ga K-, and Fe K-edge XANES spectra, it was found that more anti-site disorder of the Fe atoms is present in AlFeO 3 compared to in GaFeO 3 . Highlights: ► Al 1−x Ga x FeO 3 was investigated by X-ray absorption spectroscopy. ► Ga prefers to occupy the tetrahedral site in Al 1−x Ga x FeO 3 . ► Fe prefers to occupy the octahedral sites in Al 1−x Ga x FeO 3 as x increases. ► More anti-site disorder is present in AlFeO 3 compared to in GaFeO 3.

  9. Influence of different levels of aluminum on the development of citrus rootstock swingle citrumelo (Citrus paradisi mcf. x Poncirus trifoliata raf. in nutrient solution

    Directory of Open Access Journals (Sweden)

    Carlos Henrique dos Santos

    2000-01-01

    Full Text Available This work aimed at evaluating the influence of different levels of aluminum on the physiological parameters of the citrus rootstock Swingle Citrumelo in hydroponic solution. The experiment was carried out with a completely randomized design with three replications, subdivided in several lots. The levels of aluminum used were: 0, 7.5, 15, 22.5 and 30 mg L-1 in form of AlCl3.6H2O in nutrient solution. Following physiological parameters were evaluated: specific and relative foliar area, relative foliar mass, and the ratio of aerial part dry matter/root system dry matter. The results showed that aluminum did not influence the parameters evaluated except the specific foliar area, which decreased starting at the 7.5 mg L-1 level.O presente trabalho teve como objetivo avaliar a influência de diferentes níveis de alumínio nos parâmetros fisiológicos do porta-enxerto cítrico citrumeleiro Swingle em cultivo hidropônico. O experimento foi conduzido seguindo o delineamento estatístico inteiramente casualizado, com 3 repetições, em parcelas subdivididas. Os níveis de alumínio utilizados foram: 0, 7,5, 15, 22,5 e 30 mg L-1, na forma de AlCl3 6.H2O em solução nutritiva. Foram avaliados os parâmetros fisiológicos área foliar específica, razão de área foliar e massa foliar, relação matéria seca da parte aérea/matéria seca do sistema radicular. De acordo com os resultados obtidos nestas condições, conclui-se que os níveis de alumínio não influenciaram nos valores dos parâmetros acima discutidos, excetuando-se a AFE, havendo decréscimos destes valores a partir de 7,5 mg L-1 de alumínio.

  10. Основні принципи та правила впровадження Mobile device management і bring your own device у роботу сучасного підприємства

    Directory of Open Access Journals (Sweden)

    Олександр Олександрович Мартинюк

    2014-12-01

    Full Text Available Розглянуто основні принципи Mobile Device Management (MDM і Bring Your Own Device (BYOD та правила їх впровадження в роботу сучасного підприємства. Проаналізовано умови запобігання витоку корпоративної інформації під час використання мобільних пристроїв. Вивчено призначення, налаштування параметрів безпеки та основні можливості програмних продуктів компаній McAfee та Websense в процесі використання мобільних пристроїв у корпоративній мережі.

  11. Práticas de Gestão de Pessoas: Uma Análise a Partir da Percepção de Gerentes e não Gerentes

    Directory of Open Access Journals (Sweden)

    Ivano Ribeiro

    2015-04-01

    Full Text Available Mesmo havendo um consenso de que as práticas de Gestão de Pessoas (GP ofereçam benefícios tanto no curto quanto no médio-longo prazo, parte da literatura aponta que os investimentos nestas práticas se concentram nos cargos mais elevados de uma organização. Neste artigo, buscamos identificar como estas práticas são percebidas por empregados ocupantes de cargos gerenciais e não-gerenciais. Para a realização do estudo investigamos 131 empregados de duas diferentes instituições financeiras, um banco de varejo privado e uma cooperativa de crédito. Os dados foram analisados quantitativamente, onde dois grupos: um formado por gerentes e outro de não-gerentes foram relacionados com quatro práticas de GP: reconhecimento e estímulos; integração; comunicação; e treinamento, constructos resultantes de uma Análise Fatorial Exploratória (AFE. Os resultados indicam que os profissionais com cargos gerenciais, maior percepção das práticas de GP adotadas. A prática “treinamento” apresentou a média mais elevadas de percepção do que as demais práticas, independentemente do cargo. Observamos ainda, que o nível de percepção da prática de “treinamento” é maior em gerentes de bancos privados do que gerentes de cooperativas de crédito. Como os estudos desta natureza tendem em se concentrar na análise de práticas isoladas, este estudo contribui para o entendimento de um conjunto de práticas e de sua relação com diferentes níveis hierárquicos.

  12. Growth dynamics of two bean varieties (Phaseolus vulgaris L.. l. Growth analysis by fixed periods Dinámica de crecimiento de dos variedades de frijol (phaseolus vulgaris L. l. análisis de crecimiento por periodos fijos

    Directory of Open Access Journals (Sweden)

    Maldonado Gustavo

    1993-12-01

    frijol
    (P. vulgarís, L. comprende una serie de etapas sin las cuales no ocurrirla la formacion de frutos y en la cual el aumento de materia seca depende del comportamiento fisiológico y del hábito de crecimiento. El presente estudio evaluó el proceso de crecimiento conjuntamente con estos factores, con el propósito de establecer la diferencia en comportamiento y la
    relación entre el hábito y los índices de crecimiento en las variedades de frijol "ICA-Cerinza" de habito de crecimiento determinado e "ICA-Tundama" de habito de crecimiento indeterminado. Las variedades fueron sembradas en parcelas de 40,5 m2 y en hileras a 0,50 x 0,12 m. en un diseño de bloques completos al azar con cuatro repeticiones, en las
    cuales se tomaron muestras de tres plantas cada siete dias, a partir de los 15 y hasta los 78 dias después de emergencia. Se evaluó el peso total, el peso seco de los tallos, el peso seco de las hojas y el área foliar. A partir de éstos, se calcularon la tasa relativa de crecimiento (TRC, la tasa de asimilación neta (TAN, la relación de área foliar (RAF, la
    relación de peso foliar (RPF y el área foliar especifica
    (AFE. En las evaluaciones realizadas a los 15, 71 y 78 dias, el análisis de crecimiento por el método clásico, sólo, permitió determinar diferencias en materia seca total, de tallos, de hojas y en área foliar. Resultados similares se hallaron al analizarlos indices. La TRC fue ligeramente más alta en la variedad Cerinza que en la variedad Tundama, sin embargo,
    los valores por evaluación no fueron significativamente
    diferentes entre las dos variedades, a excepción de
    los obtenidos a los 78 D.D.E.. La TAN tuvo un comportamiento similar a la TRC y estas dos variables se correlacionaron positiva y significativamente. La RAF mostró una tendencia decreciente de tipo lineal en la variedad Cerinza, mientras que en la variedad Tundama fue de tipo cuadratico, con valores altos en las primeras y últimas

  13. Translocação orgânica, produtividade e rendimento de óleo essencial de Mentha piperita L. cultivada em solução nutritiva com variação dos níveis de N, P, K e Mg Organic translocation, productivity and essential oil yield of Mentha piperita L. cultivated in nutrient solution with varying N, P, K and Mg levels

    Directory of Open Access Journals (Sweden)

    E.F.S. David

    2009-01-01

    Full Text Available O estudo objetivou avaliar translocação orgânica, índices fisiológicos da análise de crescimento e rendimento do óleo essencial de Mentha piperita L. cultivada em solução nutritiva com variação dos níveis de N, P, K e Mg. Assim, foram avaliados os quatro tratamentos contendo 50% N, P, K, 25% Mg; 50% N, P, K, Mg; 65%N, 50%P, 25%K, 100% Mg e 100% N, P, K, Mg. A translocação orgânica foi avaliada por meio da determinação da razão de massa foliar (RMF e da distribuição de massa seca para os diferentes órgãos. Os índices fisiológicos razão de área foliar (RAF, área foliar específica (AFE, taxa assimilatória líquida (TAL e taxa de crescimento relativo (TCR derivadas que compõem a análise de crescimento foram estimados pelo programa ANACRES, após ajuste exponencial quadrático da área foliar e massa seca de lâminas foliares e total da planta em relação ao tempo. O rendimento do óleo essencial, em porcentagem, foi calculado após extração da parte aérea por hidrodestilação. As plantas submetidas ao tratamento com nível completo de nutrientes (100%N/P/K/Mg exportaram com menor eficiência o material orgânico a partir da folha e a RMF mostrou queda mais lenta, devido à retenção desse material por mais tempo no local de sua produção. Além disso, não apresentaram melhor produtividade e as curvas da TAL e TCR mostraram quedas mais lentas. As plantas submetidas ao tratamento com 65%N/50%P/25%K/100%Mg revelaram adequada exportação de matéria orgânica da folha para caule e pecíolos, conforme demonstra a RMF e a distribuição de massa seca para esses órgãos. Revelaram ainda a RAF mais elevada no inicio do desenvolvimento e mais baixa aos 94 DAT, indicando sombreamento das folhas como resultado de seu crescimento. A AFE dessas plantas mostrou menor variação durante o ciclo, refletindo espessura mais constante de suas folhas. A TAL e a TCR apresentaram curvas decrescentes, com quedas bem acentuadas em

  14. Nutritional status and specific leaf area of mahogany and tonka bean under two light environments Estado nutricional e área foliar específica de mogno e cumaru sob dois ambientes de luz

    Directory of Open Access Journals (Sweden)

    José Francisco de C. Gonçalves

    2005-01-01

    de idade, crescidas em plantio a céu aberto (sol com cerca de 2000 µmol m-2 s-1 e sob cobertura natural (sombra de plantas de pau-de-balsa (Ochroma pyramidale Cav. Ex Lam. Urb com cerca de 260 µmol m-2 s-1, foram analisadas quanto à área foliar (AF, a massa da matéria seca (MMS, a área foliar específica (AFE e aos teores de nutrientes foliares. Verificou-se que, folhas de S. macrophylla, crescidas a pleno sol, apresentaram AF 35% menor quando comparadas com as folhas crescidas na sombra. Por outro lado, nas folhas de D. odorata, não foram observadas diferenças para AF entre os ambientes. Adicionalmente, observou-se que folhas de sombra de S. macrophylla, com base na MMS, foram 50% menores que as folhas de sol, enquanto que no D. odorata não foram observadas diferenças para MMS entre os ambientes. Quanto a AFE, nas folhas de S. macrophylla, verificou-se que as folhas de sol foram três vezes menores quando comparadas com as folhas de sombra, e não houve diferença nas folhas do D. odorata. Quanto aos teores dos nutrientes verificou-se que, independentemente do ambiente, folhas de S. macrophylla apresentaram maiores teores de P e Ca do que aqueles encontrados nas folhas do D. odorata. Os teores de N, K, Fe e Mn diminuíram nas folhas de S. macrophylla crescidas a sombra. Por último, nós sugerimos que a diminuição no teor dos nutrientes foliares pode ter influência negativa sobre o crescimento foliar. Os resultados demonstram que a hipótese testada é verdadeira para características foliares, D. odorata, classificada como clímax, exibiu menor plasticidade para características foliares quando comparada com S. macrophylla, classificada como intermediária.

  15. Empresas de Auditoria e o Compliance com o Nível de Evidenciação Obrigatório Durante o Processo de Convergência às Normas Internacionais de Contabilidade no BrasilBusiness and Compliance Audit with Mandatory Disclosure level During the Convergence of International Accounting Standards in BrazilNegocio de Auditoría y Cumplimiento del Nivel del Divulgación Obligatoria Durante la Convergencia de las Normas Internacionales de Contabilidad en Brasil

    Directory of Open Access Journals (Sweden)

    MAIA, Henrique Araújo

    2012-09-01

    Full Text Available RESUMOO objetivo deste estudo foi verificar quais variáveis influenciam o nível de evidenciação mínima das companhias abertas brasileiras durante o período inicial de harmonização às normas internacionais de contabilidade no Brasil. Sob o aspecto metodológico, o estudo é qualitativo-quantitativo, do tipo descritivo. A população-alvo foi formada pelas companhias abertas brasileiras não financeiras que compõem o índice IBRX da Bovespa, cuja amostra final foi composta por 78 empresas. Os dados foram extraídos das demonstrações contábeis e notas explicativas das companhias, nos períodos de 2008 e 2009, por meio do banco de dados da Economática e do site da CVM. A partir da utilização de um índice de evidenciação mínima, composto por 72 itens relativos a pronunciamentos e orientações técnicas emitidos pelo Comitê de Pronunciamentos Contábeis (CPC, foi determinado o nível de evidenciação mínima para cada empresa da amostra. O tratamento dos dados qualitativos foi realizado por meio da análise de conteúdo e dos quantitativos com a técnica de Análise Fatorial Exploratória (AFE e de Modelos Lineares Generalizados (MLG. Os principais resultados apresentaram que o porte das empresas de auditoria, a internacionalização, o nível de governança corporativa e o nível de endividamento influenciam significativamente o nível de evidenciação mínima das empresas. Esse achado sugere que as companhias abertas da amostra, auditadas pelas big four, apresentam melhor qualidade na divulgação de informação contábil do que aquelas auditadas por outras empresas de auditoria independentes.ABSTRACTThe aim of this study was to establish the variables that influence the level of minimal disclosure of open Brazilian companies during the initial period of harmonization with international accounting standards in Brazil. Under the methodological aspect, the study is qualitative-quantitative, of a descriptive type. The target

  16. Aspectos fisiológicos e crescimento do algodoeiro ‘BRS topázio’ cultivado com águas salinas e adubação potássica

    Directory of Open Access Journals (Sweden)

    Jessica Dayanne Capitulino

    2017-06-01

    Full Text Available Objetivou-se avaliar os índices fisiológicos e o crescimento do algodoeiro colorido cv. BRS Topázio submetido à irrigação com águas de diferentes níveis de salinidades e adubação com doses de potássio. O experimento foi conduzido em vasos sob condições de casa de vegetação, utilizando-se um Neossolo Regolítico Eutrófico de textura franco-arenoso não salino. Utilizaram-se o delineamento de blocos casualizados, com 4 repetições, cujos tratamentos foram distribuídos em esquema fatorial 4 x 4, sendo quatro níveis de condutividade elétrica da água de irrigação (CEa (1,5; 3,0; 4,5 e 6,0 dS m-1 e quatro doses de potássio (50; 75; 100 e 125% da recomendação, sendo a dose de 100% correspondente a 150 mg K2O por kg-1 de solo. Avaliaram-se os efeitos dos tratamentos sobre a concentração interna de CO2 (Ci, transpiração (E, condutância estomática (gs, taxa de assimilação de CO2 (A, eficiência no uso da água (EiUA e a eficiência instantânea da carboxilação (EICi, fitomassa seca das folhas (FSF, fitomassa seca do caule (FSC, fitomassa seca da parte aérea (FSA, área foliar especifica (AFE e no período compreendido entre 30 e 130 dias determinaram-se a taxa de assimilação líquida (TAA. As trocas gasosas e a fitomassa seca da folha, a fitomassa seca do caule e a fitomassa seca da parte aérea do algodoeiro colorido cv. BRS Topázio reduz acentuadamente, quando submetida a níveis de CEa maior que 1,5 dS m-1. A área foliar especifica e a taxa de assimilação líquida do algodoeiro BRS Topázio não foram afetados pela água de irrigação com água salina. A adubação potássica não exerceu influência sobre as variáveis de analisadas do algodoeiro colorido. Não houve interação entre os fatores salinidade da água de irrigação versus doses de potássio para as variáveis analisadas.Physiological aspects and growth of 'BRS topázio' cotton cultivated with salt waters and potassic fertilizationThe objective

  17. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    Science.gov (United States)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  18. Analisis de crecimiento de Limonium sinuatum Mill cv. Midnight Blue propagada sexual y asexualmente a partir de yemas vegetativas y florales.

    Directory of Open Access Journals (Sweden)

    Pedroza Jaime

    1997-06-01

    Full Text Available

    Se realizo el análisis clásico de crecimiento de plantas de estatice (Limonium sinuatum Mill. cv. Midnight Blue propagadas sexualmente y mediante los sistemas in vitro, a partir de yemas vegetativas y florales bajo condiciones de invernadero en la Sabana de Bogotá, Colombia, mediante el empleo de 10 índices que evalúan el desempeño fisiológico del material vegetal. En este cultivar es característico el comportamiento oscilatorio y simétrico de algunos índices que evidencian una posible actividad fisiológica muy particular en la relación Fuente: Demanda; Así, la exportaci6n de fotoasimilados (RAF esta afectada por su retención en las hojas (AFE, especialmente durante la fase vegetativa. De igual forma. es importante destacar que, en la fase reproductiva, los tallos florales son la principal demanda de fotosintatos. Con respecto a la T.R.C., se nota que detalla muy bien el crecimiento vegetativo y es afectada por la T.A.N., mientras que la T.C.C, el reproductivo.

    Aunque se presentaron algunas diferencias cuantitativas en la fase vegetativa, en la reproductiva, presumiblemente, por efectos fisiológicos compensatorios, ocurre total homogeneidad entre los tipos de plantas analizadas.

  19. Synthesis and properties of ternary (K, NH{sub 4}, H{sub 3}O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sandy Jones, F.; Bigham, Jerry M. [School of Environment and Natural Resources, Ohio State University, 2021 Coffey Road, Columbus, OH 43210 (United States); Gramp, Jonathan P. [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States); Tuovinen, Olli H., E-mail: tuovinen.1@osu.edu [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States)

    2014-11-01

    The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K{sup +} (0, 1, 4, 6, 12, 31 mM) and NH{sub 4}{sup +} (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO{sub 4} solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) and/or schwertmannite (idealized formula Fe{sub 8}O{sub 8}(OH){sub 6}(SO{sub 4})·nH{sub 2}O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K{sup +} (≤ 4 mM) and NH{sub 4}{sup +} (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K{sup +} and NH{sub 4}{sup +} are similar, K{sup +} greatly facilitated the formation of a jarosite phase compared to NH{sub 4}{sup +}. Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH{sub 4}, H{sub 3}O)-solid solutions that were also deficient in structural Fe, especially at low NH{sub 4} contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K{sup +} and NH{sub 4}{sup +} in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH{sub 4}-jarosite were detected in the un-aged precipitates

  20. Análise de crescimento do capim-marandu submetido a doses de nitrogênio Growth analysis of marandugrass in response to nitrogen rates

    Directory of Open Access Journals (Sweden)

    João de Deus Gomes dos Santos Junior

    2004-12-01

    Full Text Available Marandu, submetida a doses de nitrogênio (N na solução nutritiva (28, 112, 210, 294 e 378 mg/L, na proporção constante de 70%:30% entre N-NO3- e N-NH4+, em diferentes idades de crescimento (21, 28, 35, 42, 49 e 56 dias após a emergência. O experimento foi conduzido em casa-de-vegetação, em solução nutritiva, e utilizando sílica como substrato. O delineamento experimental foi o de blocos completos ao acaso, com quatro repetições, em arranjo fatorial 5x6. As doses de N e as idades de crescimento interagiram significativamente em todos os atributos de crescimento do capim-marandu, com exceção da taxa de assimilação líquida (TAL. Constatou-se valor máximo para a taxa de crescimento relativo (TCR e taxa de crescimento absoluto (TCA, respectivamente, de 0,25 g/g.dia à idade de 28 dias, com o N na solução em 378 mg/L e 3,68 g/dia, aos 56 dias de crescimento, com a dose de N de 378 mg/L. Aos 21 dias de crescimento, verificaram-se valores máximos de 2,16 dm²/g para a razão de área foliar (RAF, com a mais alta dose de N, 0,48 g/g para a razão de massa foliar (RMF, com N na dose de 294 mg/L e de 5,14 dm²/g para a área foliar específica (AFE, com o suprimento de N na solução em 378 mg/L.This research was conducted with the objective of determining growth of Brachiaria brizantha (A. Rich. Stapf. cv. Marandu under nitrogen (N rates (28, 112, 210, 294 and 378 mg/L, where N-NO3- : N-NH4+ of 70%:30% proportion was kept constant and growth ages (21, 28, 35, 42, 49 and 56 days after seedling emergence. The experiment was carried out in greenhouse conditions, with nutrient solution and using ground quartz as substrate. The experimental design used was a complete randomized block design, with treatments arranged in a 5x6 factorial, with four replications. Nitrogen rates and growth ages interaction was significant for all growth attributes of Marandugrass, except for the mean net assimilation rate (NAR. The results showed that the