Filled Co (sub X) Ni (sub 4-x) Sb (sub 12-y) Sn (sub Y) Skutterudites: Processing and Thermoelectric Properties

NASA Technical Reports Server (NTRS)

Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

2015-01-01

Skutterudites have proven to be a useful thermoelectric system as a result of their enhanced figure of merit (ZT1), cheap material cost, favorable mechanical properties, and good thermal stability. The majority of skutterudite interest in recent years has been focused on binary skutterudites like CoSb3 or CoAs3. Binary skutterudites are often double and triple filled, with a range of elements from the lanthanide series, in order to reduce the lattice component of thermal conductivity. Ternary and quaternary skutterudites, such as Co4Ge6Se6 or Ni4Sb8Sn4, provide additional paths to tune the electronic structure. The thermal conductivity can further be improved in these complex skutterudites by the introduction of fillers. The Co (sub X) Ni (sub 4-x) Sb (sub 12-y) Sn (sub Y) system has been investigated as both a p- and n-type thermoelectric material, and is stable up to 200 degrees Centigrade. Yb, Ce, and Dy fillers have been introduced into the skutterudite to study the influence of both the type and the quantity of fillers on processing conditions and thermoelectric properties. The system was processed through a multi-step technique that includes solidification, mechano-chemical alloying, and hot pressing which will be discussed along with thermoelectric transport properties.

Magnetism in Na-filled Fe-based skutterudites

DOE PAGES

Xing, Guangzong; Fan, Xiaofeng; Zheng, Weitao; ...

2015-06-01

The interplay of superconductivity and magnetism is a subject of ongoing interest, stimulated most recently by the discovery of Fe-based superconductivity and the recognition that spin-fluctuations near a magnetic quantum critical point may provide an explanation for the superconductivity and the order parameter. We investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe 4Sb 12 is a known ferromagnet near a quantum critical point. We find a ferromagnetic metallic state for this compound driven by a Stoner type instability, consistent with prior work. In accord with prior work, the magnetization is overestimated, as expected for amore » material near an itinerant ferromagnetic quantum critical point. NaFe 4P 12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe 4Sb 12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe 4As 12 shows intermediate behavior. We also present results for skutterudite FeSb 3, which is a metastable phase that has been reported in thin film form.« less

Structural, electronic, and thermal properties of indium-filled InxIr4Sb12 skutterudites

NASA Astrophysics Data System (ADS)

Wallace, M. K.; Li, Jun; Subramanian, M. A.

2018-06-01

The "phonon-glass/electron-crystal" approach has been implemented through incorporation of "rattlers" into skutterudite void sites to increase phonon scattering and thus increase the thermoelectric efficiency. Indium filled IrSb3 skutterudites are reported for the first time. Polycrystalline samples of InxIr4Sb12 (0 ≤ x ≤ 0.2) were prepared by solid-state reaction under a gas mixture of 5% H2 and 95% Ar. The solubility limit of InxIr4Sb12 was found to be close to 0.18. Synchrotron X-ray diffraction refinements reveal all InxIr4Sb12 phases crystallized in body-centered cubic structure (space group : Im 3 bar) with ∼8% antimony site vacancy and with indium partially occupying the 16f site. Unlike known rattler filled skutterudites, under synthetic conditions employed, indium filling in IrSb3 significantly increases the electrical resistivity and decreases the Seebeck coefficient (n-type) while reducing the thermal conductivity by ∼30%. The resultant power factor offsets the decrease in total thermal conductivity giving rise to a substantial decrease in ZT. Principal thermoelectric properties of InxM4Sb12 (M = Co, Rh, Ir) phases are compared. As iridium is a 5d transition metal, zero field cooled (ZFC) magnetization were performed to unravel the effect of spin-orbit interaction on the electronic properties. These results serve to advance the understanding of filled skutterudites, and provide additional insight on the less explored smaller "rattlers" and their influence on key thermoelectric properties.

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs4Sb12

NASA Astrophysics Data System (ADS)

Levenson-Falk, E. M.; Schemm, E. R.; Aoki, Y.; Maple, M. B.; Kapitulnik, A.

2018-05-01

We present polar Kerr effect measurements of the filled skutterudite superconductor PrOs4 Sb12 . Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θK develops below the superconducting transition, saturating at ˜300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θK(T ) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at TC 2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs4 Sb12 .

Beneficial Effect of S-Filling on Thermoelectric Properties of S x Co4Sb11.2Te0.8 Skutterudite

NASA Astrophysics Data System (ADS)

Wang, Hongtao; Duan, Bo; Bai, Guanghui; Li, Jialiang; Yu, Yue; Yang, Houjiang; Chen, Gang; Zhai, Pengcheng

2018-06-01

In this work, Te-doped and S-filled S x Co4Sb11.2Te0.8 ( x = 0.1, 0.15, 0.2, 0.25, 0.3, 0.4) skutterudite compounds have been prepared using solid state reaction and spark plasma sintering. Thermoelectric measurements of the consolidated samples were examined in a temperature range of 300-850 K, and the influences of S-addition on the thermoelectric properties of S x Co4Sb11.2Te0.8 skutterudites are systematically investigated. The results indicate that the addition of sulfur and tellurium is effective in reducing lattice thermal conductivity due to the point-defect scattering caused by tellurium substitutions and the cluster vibration brought by S-filling. The solubility of tellurium in skutterudites is enhanced with sulfur addition via charge compensation. The thermal conductivity decreases with increasing sulfur content. The highest figure of merit, ZT = 1.5, was obtained at 850 K for S0.3Co4Sb11.2Te0.8 sample, because of the low lattice thermal conductivity.

NMR study of partially filled skutterudites AxCo4Sb12 (A = Yb, Ba, Sr, Ca) and BaxYbyCo4Sb12.

NASA Astrophysics Data System (ADS)

Tian, Yefan; Sirusi, Ali; Ross, Joseph; Ballikaya, Sedat; Uher, Ctirad; Chen, Yuqi; Sekine, Chihiro

Partially filled Co-Sb skutterudites have been of considerable interest as thermoelectric materials, particularly with multiple filling for which high ZT values can be obtained. This is due in part to control of phonon thermal conductivity, but also the change in composition leads to subtle changes in electronic behavior as well as magnetism due both to rare earth filler atoms and to native defects. We measured 59Co NMR on several partially filled AxCo4Sb12 skutterudites in order to investigate such behavior. From the T-dependent NMR shifts along with T1 relaxation times we can separate metallic shift contributions from those due to local moments. We compare the results to predicted band-edge behavior with multiple minima, and the estimated g factors, by matching this behavior to transport measurements. Also the behavior of Yb-filled samples provides an estimate of the conduction band mediation of the magnetic response, and we also find magnetic shifts in Ba-doped skutterudite which we address in terms of Co mixed-valence behavior. This work was supported by the Robert A. Welch Foundation, Grant No. A-1526. Synthesis work was partly supported by the Center for Solar and Thermal Energy Conversion and a Grant-in-Aid for Scientific Research (B) (No. 23340092) from the Japan Society.

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs 4 Sb 12

DOE PAGES

Levenson-Falk, Eli M.; Schemm, E. R.; Aoki, Y.; ...

2018-05-04

Here, we present polar Kerr effect measurements of the filled skutterudite superconductor PrOs 4Sb 12. Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θ K develops below the superconducting transition, saturating at ~300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θ K(T) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at Tmore » C2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs 4Sb 12.« less

Polar Kerr Effect from Time-Reversal Symmetry Breaking in the Heavy-Fermion Superconductor PrOs 4 Sb 12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levenson-Falk, Eli M.; Schemm, E. R.; Aoki, Y.

Here, we present polar Kerr effect measurements of the filled skutterudite superconductor PrOs 4Sb 12. Simultaneous ac susceptibility measurements allow us to observe the superconducting transition under the influence of heating from the optical beam. A nonzero Kerr angle θ K develops below the superconducting transition, saturating at ~300 nrad at low temperatures. This result is repeated across several measurements of multiple samples. By extrapolating the measured θ K(T) to zero optical power, we are able to show that the Kerr angle onset temperature in one set of measurements is consistent with the transition to the B phase at Tmore » C2. We discuss the possible explanations for this result and its impact on the understanding of multiphase and inhomogeneous superconductivity in PrOs 4Sb 12.« less

Thermoelectric and mechanical properties on misch metal filled p-type skutterudites Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahal, Tulashi; Jie, Qing; Dahal, Keshab

2015-02-07

Most of the recent work focused on improving the dimensionless figure-of-merit, ZT, of p-type skutterudites uses one or two fillers to tune the electrical and thermal properties. Considering the fact that the different fillers with varying atomic mass and ionic radii can vibrate with different amplitudes to scatter phonons of different mean free paths, we synthesized misch metal filled p-type skutterudites Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12} (where Mm is La{sub 0.25}Ce{sub 0.5}Pr{sub 0.05}Nd{sub 0.15}Fe{sub 0.03}, called misch metal). The samples were synthesized by hot pressing nano-powder made by ball milling the annealed ingot of Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12} withmore » varying concentration of cobalt, x. By tuning the Fe/Co ratio, we achieved a thermal conductivity of ∼2 W m{sup −1} K{sup −1} at room temperature and ∼2.3 W m{sup −1} K{sup −1} at about 530 °C and a power factor of ∼30 μW cm{sup −1} K{sup −2} at about 425 °C in Mm{sub 0.9}Fe{sub 3.1}Co{sub 0.9}Sb{sub 12}, leading to a peak ZT ∼1.1 at about 425 °C. The nano-indentation experiment reveals that hardness and elastic modulus of the material is about 4.2 GPa and 116 GPa, respectively.« less

Charge Transport and Thermoelectric Properties of (Nd1- z Yb z ) y Fe4- x Co x Sb12 Skutterudites

NASA Astrophysics Data System (ADS)

Shin, Dong-Kil; Jang, Kyung-Wook; Choi, Soon-Mok; Lee, Soonil; Seo, Won-Seon; Kim, Il-Ho

2018-06-01

Partially double-filled (Nd1- z Yb z ) y Fe4- x Co x Sb12 ( z = 0.25, 0.75, y = 0.8, and x = 0, 0.5, 1.0) skutterudites were prepared by encapsulated melting, annealing, and hot pressing, and the effects of Nd/Yb partial double filling and Co charge compensation on the microstructure, charge transport, and thermoelectric properties were investigated. All the specimens were transformed to the skutterudite phase together with a few secondary phases such as FeSb2, but FeSb2 formation was suppressed on increasing Co content. Nd and Yb were successfully double-filled in the voids of the skutterudite lattice and Co was well substituted at Fe sites, as indicated by changes in the lattice constant with Nd/Yb filling and Fe/Co substitution. All the specimens showed p-type conduction and exhibited degenerate semiconductor characteristics at temperatures from 323 K to 823 K, and the charge transport properties depended on the filling ratio of Nd and Yb because of the difference between the valencies of Nd and Yb. The electrical conductivity decreased and the Seebeck coefficient increased owing to a decrease in the carrier concentration with increasing Co content. The lattice thermal conductivity decreased because phonon scattering was enhanced by Nd and Yb partial double filling, but partially double-filled specimens did not exhibit a further significant reduction in the lattice thermal conductivity compared with the completely double-filled specimens. A maximum ZT of 0.83 was obtained for (Nd0.75Yb0.25)0.8Fe3CoSb12 at 723 K.

Unusual Phase Diagram of CeOs 4Sb 12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, P. -C.; Goddard, P. A.; Maple, M. B.

2017-03-01

Filled skutterudite compounds, with the formula MT 4X 12, where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os, and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1]. Among these, the three compounds CeOs 4Sb 12, PrOs 4Sb 12, and NdOs 4Sb 12, formed by employing Periodic Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal (M = Ce) via a 1.85 K unconventional (quadrupolar-fluctuation mediated) superconductor (M = Pr) to a 1 K ferromagnet (FM; M = Nd). Inmore » the course of an extended study of these compounds, we uncovered an unusual phase diagram for CeOs 4Sb 12.« less

Configuring pnicogen rings in skutterudites for low phonon conductivity

NASA Astrophysics Data System (ADS)

Uher, Ctirad

2013-03-01

During the past dozen or so years, skutterudites have attracted much interest as prospective thermoelectric materials for power-generation applications in the temperature range 500K - 850K. Primary interest was focused on filled forms of skutterudites where loosely-bonded filler species resonantly scatter normal phonon modes of the structure thus reducing the lattice thermal conductivity. Using this approach with multiple fillers and incorporating various forms of nanoinclusions, impressive figures of merit ZT = 1.5-1.7 have been reported with n-type filled skutterudites. Since the dominant heat-carrying modes in skutterudites are associated with vibrations of the pnicogen rings, disruptions of the ring structure by substitutional alloying should be a similarly effective approach of lowering the lattice thermal conductivity. In this talk I discuss our recent work exploring alloying configurations of pnicogen rings that yield particularly low values of the thermal conductivity. We found that compensated double-substitution (replacing two Sb atoms with one atom each from the column IV and column VI elements) is a very effective approach. Our ab initio calculations, in combination with a cluster expansion, have allowed us to identify stable alloy configurations on the Sb rings. Subsequent molecular and lattice dynamics simulations on low energy configurations established the range of atomic displacement parameters and values of the thermal conductivity. Theoretical results turned out to be in good agreement with our experimental thermal conductivity values. Combining both approaches of compensated double-substitution and filling of structural cages should be an effective way of further improving the thermoelectric figure of merit of skutterudites. Work supported by the Center for Solar and Thermal Energy Conversion, and Enegy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0000957

Exceeding the filling fraction limit: An approach to enhancement of thermoelectric properties of filled - Co4Sb12 skutterudite

NASA Astrophysics Data System (ADS)

Graff, Jennifer Whitney

Currently the world energy usage has nearly tripled since 1950 and is projected to grow at a rate of 1.5% per year and predicted to at least double from the beginning of the millennium to 2050. The United States alone is currently consuming more energy than it can produce (≈ 97 Quadrillion BTU's consumed in 2011).(1) Presently, fossil fuels make up over 85% of our energy landscape, including both the stationary grid (like coal and nuclear power plants) and the mobile grid (automobiles using gas and oil). This presents a major demand for developing methods of saving, storing, and renewing energy. Answers to these existing energy demands must come from a variety of renewable sources including: solar, wind, biomass, geothermal and others. But currently, most renewable sources are only a small part of the big energy picture. One approach to this exponentially growing problem, lies within high efficiency (15%-20%) thermoelectric (TE) materials which address small, yet very important and specific, parts of a bigger problem. Specifically, Co4Sb12-based skutterudites, an increasingly favorable thermoelectric material for mid to high temperature applications (currently used in General Motors TE Generator devices). These materials have the ability to be 'tuned' or controlled thermally and electrically through doping and filling mechanisms, as you will see in this dissertation. However, one of the major drawbacks of TE materials is the difficulty in optimizing both electrical and thermal properties simultaneously. Typically, different control parameters are used in order to enhance the electrical and thermal properties individually. It is very rare to observe optimization of both in a TE material via one control parameter. However, the work presented herein successfully augments all TE properties, with one control variable, by using an approach that can be applied to all doped skutterudites and clathrate materials. Skutterudites are novel materials in that they are a binary system with a crystalline framework and a narrow band gap, so they naturally possess relatively good electrical properties. This dissertation seeks to answer the question: Can we continue to improve the efficiency of one of the leading TE materials in power generation applications -- skutterudites? In trying to answer this question we discovered a material that had never been tested for its TE properties and found that it exhibits behavior not typically observed in these materials as well as showing improvements in all TE properties (electrical and thermal) via one control parameter. We also successfully improved the TE efficiencies of several different filled skutterudites by a single approach which can be applied to other skutterudite and cage-like materials.

Localized vibrational modes in thallium-filled skuterudites

NASA Astrophysics Data System (ADS)

Petculescu, Gabriela; Keppens, Veerle; Taylor, Andrew; Sales, Brian; Mandrus, David

2003-03-01

Elastic constant measurements using Resonant Ultrasound Spectroscopy have been performed on Tl_xCo_ 4Sb_12-ySny skutterudites as a function of temperature and Tl filling ratio, x (y = 0 or 1, for small and large values of x, respectively). In addition to being promising thermoelectric materials (ZT = 0.8 at T = 800 K) [1], these Tl-filled compounds provide a ``clean'' system to investigate the mechanism involved in the lattice thermal conductivity drop. The behavior of the elastic constants at low temperatures depends directly on the rattling atoms' (e.g.: Tl) local vibrational modes which could be associated with an Einstein oscillator or a two-level system. This was previously illustrated for the lanthanum-filled skutterudite La_0.75 Fe_3CoSb_12 [2]. In the present study, we examine the influence of the rattler filling ratio on the dominant mechanism of excitation. The results will be discussed and compared with findings in related skutterudite and clathrate compounds. [Work supported by the National Science Foundation and the Office of Naval Research.] [1] B. C. Sales et al., Phys. Rev. B 61, 2475-2481 (2000). [2] V. Keppens et al., Nature 395, 876-878 (1998).

Collective-Goldstone-mode-induced ultralow lattice thermal conductivity in Sn-filled skutterudite SnFe4Sb12

NASA Astrophysics Data System (ADS)

Fu, Yuhao; He, Xin; Zhang, Lijun; Singh, David J.

2018-01-01

We demonstrate that the concept of Goldstone bosons can be exploited for phonon control and thermal conductivity reduction of materials. By studying lattice dynamics of the Sn filled skutterudite SnFe4Sb12 , we find Sn off-centers in its coordination cage in contrast to the common rare earth fillers. This leads to low-frequency Goldstone-like modes below 1 THz associated mainly with Sn motions. Importantly, these involve collective motion of other atoms, especially Sb, in the host skutterudite lattice. The optical modes transversing to the Sn off-centering direction are identified as Goldstone type modes in association with a three-dimensional Mexican-hat-like potential energy surface. The interaction of these collective Goldstone modes with the host heat-carrying phonons is shown to lead to ultralow lattice thermal conductivity.

Panoscopic approach for high-performance Te-doped skutterudite

DOE PAGES

Liang, Tao; Su, Xianli; Yan, Yonggao; ...

2017-02-24

One-step plasma-activated sintering (OS-PAS) fabrication of single-phase high-performance CoSb 3-based skutterudite thermoelectric material with a hierarchical structure on a time scale of a few minutes is first reported here. The formation mechanism of the CoSb 3 phase and the effects of the current and pressure fields on the phase transformation and microstructure evolution are studied in the one-step PAS process. The application of the panoscopic approach to this system and its effect on the transport properties are investigated. The results show that the hierarchical structure forms during the formation of the skutterudite phase under the effects of both current andmore » sintering pressure. The samples fabricated by the OS-PAS technique have defined hierarchical structures, which scatter phonons more intensely over a broader range of frequencies and significantly reduce the lattice thermal conductivity. High-performance bulk Te-doped skutterudite with the maximum ZT of 1.1 at 820 K for the composition CoSb 2.875Te 0.125 was obtained. Such high ZT values rival those obtained from single filled skutterudites. As a result, this newly developed OS-PAS technique enhances the thermoelectric performance, dramatically shortens the synthesis period and provides a facile method for obtaining hierarchical thermoelectric materials on a large scale.« less

Structure, microstructure and microhardness of rapidly solidified Smy(FexNi1-x)4Sb12 (x = 0.45, 0.50, 0.70, 1) thermoelectric compounds

NASA Astrophysics Data System (ADS)

Artini, C.; Castellero, A.; Baricco, M.; Buscaglia, M. T.; Carlini, R.

2018-05-01

Skutterudites are interesting compounds for thermoelectric applications. The main drawback in the synthesis of skutterudites by solidification of the melt is the occurrence of two peritectic reactions requiring long annealing times to form a single phase. Aim of this work is to investigate an alternative route for synthesis, based on rapid solidification by planar flow casting. The effect of cooling rate on phases formation and composition, as well as on structure, microstructure and mechanical properties of the filled Smy(FexNi1-x)4Sb12 (x = 0.45, 0.50, 0.70, 1) skutterudites was studied. Conversely to slowly cooled ingots, rapidly quenched ribbons show skutterudite as the main phase, suggesting that deep undercooling of the liquid prevents the nucleation of high temperature phases, such as (Fe,Ni)Sb and (Fe,Ni)Sb2. In as-quenched samples, a slightly out of equilibrium Sm content is revealed, which does not alter the position of the p/n boundary; nevertheless, it exerts an influence on crystallographic properties, such as the cell parameter and the shape of the Sb4 rings in the structure. As-quenched ribbons show a fine microstructure of the skutterudite phase (grain size of 2-20 μm), which only moderately coarsens after annealing at 873 K for 4 days. Vickers microhardness values (350-400 HV) of the skutterudite phase in as-quenched ribbons are affected by the presence of softer phases (i.e. Sb), which are homogeneously and finely dispersed within the sample. The skutterudite hardens after annealing as a consequence of a moderate grain growth, which limits the matrix effect due to the presence of additional phases.

Collective-Goldstone-mode-induced ultralow lattice thermal conductivity in Sn-filled skutterudite SnFe 4 Sb 12

DOE PAGES

Fu, Yuhao; He, Xin; Zhang, Lijun; ...

2018-01-03

Here, we demonstrate that the concept of Goldstone bosons can be exploited for phonon control and thermal conductivity reduction of materials. By studying lattice dynamics of the Sn filled skutterudite SnFe 4Sb 12, we find Sn off-centers in its coordination cage in contrast to the common rare earth fillers. This leads to low-frequency Goldstone-like modes below 1 THz associated mainly with Sn motions. Importantly, these involve collective motion of other atoms, especially Sb, in the host skutterudite lattice. The optical modes transversing to the Sn off-centering direction are identified as Goldstone type modes in association with a three-dimensional Mexican-hat-like potentialmore » energy surface. The interaction of these collective Goldstone modes with the host heat-carrying phonons is shown to lead to ultralow lattice thermal conductivity.« less

Collective-Goldstone-mode-induced ultralow lattice thermal conductivity in Sn-filled skutterudite SnFe 4 Sb 12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Yuhao; He, Xin; Zhang, Lijun

Here, we demonstrate that the concept of Goldstone bosons can be exploited for phonon control and thermal conductivity reduction of materials. By studying lattice dynamics of the Sn filled skutterudite SnFe 4Sb 12, we find Sn off-centers in its coordination cage in contrast to the common rare earth fillers. This leads to low-frequency Goldstone-like modes below 1 THz associated mainly with Sn motions. Importantly, these involve collective motion of other atoms, especially Sb, in the host skutterudite lattice. The optical modes transversing to the Sn off-centering direction are identified as Goldstone type modes in association with a three-dimensional Mexican-hat-like potentialmore » energy surface. The interaction of these collective Goldstone modes with the host heat-carrying phonons is shown to lead to ultralow lattice thermal conductivity.« less

High-performance n-type Yb xCo 4Sb 12: from partially filled skutterudites towards composite thermoelectrics

DOE PAGES

Wang, Shanyu; Salvador, James R.; Yang, Jiong; ...

2016-07-01

The filling fraction limit (FFL) of skutterudites, that is, the complex balance of formation enthalpies among different species, is an intricate but crucial parameter for achieving high thermoelectric performance. In this work, we synthesized a series of Yb xCo 4Sb 12 samples with x=0.2–0.6 and systemically studied the FFL of Yb, which is still debated even though this system has been extensively investigated for decades. Our combined experimental efforts of X-ray diffraction, microstructural and quantitative compositional analyses clearly reveal a Yb FFL of ~0.29 in CoSb 3, which is consistent with previous theoretical calculations. For the excess Yb in samplesmore » with x>0.35 mainly form metallic YbSb 2 precipitates, the Fermi level increases significantly and thus increases the electrical conductivity and decreasing the Seebeck coefficient. Our result is further corroborated by the numerical calculations based on the Bergman’s composite theory, which accurately reproduces the transport properties of the x>0.35 samples based on nominal Yb 0.35Co 4Sb 12 and YbSb 2 composites. A maximum ZT of 1.5 at 850 K is achieved for Yb 0.3Co 4Sb 12, which is the highest value for a single-element-filled CoSb 3. The high ZT originates from the high-power factor (in excess of 50 μW cm -K -2) and low lattice thermal conductivity (well below 1.0 W m -K -1). More importantly, the large average ZTs, for example, ~1.05 for 300–850 K and ~1.27 for 500–850 K, are comparable to the best values for n-type skutterudites. The high thermoelectric and thermomechanical performances and the relatively low air and moisture sensitivities of Yb make Yb-filled CoSb 3, a promising candidate for large-scale power generation applications.« less

Co(x)Ni(4-x)Sb(12-y)Sn(y) Ternary Skutterudites: Processing and Thermoelectric Properties

NASA Technical Reports Server (NTRS)

Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

2014-01-01

Skutterudites have proven to be a useful thermoelectric system as a result of their high figure of merit, favorable mechanical properties, and good thermal stability. Binary skutterudites have received the majority of interest in recent years, as a result of successful double and triple filling schemes. Ternary skutterudites, such as Ni4Sb7Sn5, also demonstrate good thermoelectric performance, with high power factor and low thermal conductivity. Ternary skutterudites, as contrasted to binary systems, provide more possibility for tuning electronic structure as substitutions can be studied on three elements. The Co(x)Ni(4-x)Sb(12-y)Sn(y) system has been investigated as both a p- and n-type thermoelectric material, stable up to 200 C. The system is processed through a combination of solidification, mechanical alloying, and hot pressing steps. Rietveld structure refinement has revealed an interesting occupancy of Sn on both the 24g Wyckoff position with Sb as well as the 2a position as a rattler. In addition to thermoelectric properties, detailed processing routes have been investigated on the system.

Thermoelectric skutterudite compositions and methods for producing the same

DOEpatents

Ren, Zhifeng; Yang, Jian; Yan, Xiao; He, Qinyu; Chen, Gang; Hao, Qing

2014-11-11

Compositions related to skutterudite-based thermoelectric materials are disclosed. Such compositions can result in materials that have enhanced ZT values relative to one or more bulk materials from which the compositions are derived. Thermoelectric materials such as n-type and p-type skutterudites with high thermoelectric figures-of-merit can include materials with filler atoms and/or materials formed by compacting particles (e.g., nanoparticles) into a material with a plurality of grains each having a portion having a skutterudite-based structure. Methods of forming thermoelectric skutterudites, which can include the use of hot press processes to consolidate particles, are also disclosed. The particles to be consolidated can be derived from (e.g., grinded from), skutterudite-based bulk materials, elemental materials, other non-Skutterudite-based materials, or combinations of such materials.

Thermoelectric Skutterudite Compositions and Methods for Producing the Same

NASA Technical Reports Server (NTRS)

Yang, Jian (Inventor); Yan, Xiao (Inventor); Ren, Zhifeng (Inventor); Hao, Qing (Inventor); He, Qinyu (Inventor); Chen, Gang (Inventor)

2014-01-01

Compositions related to skutterudite-based thermoelectric materials are disclosed. Such compositions can result in materials that have enhanced ZT values relative to one or more bulk materials from which the compositions are derived. Thermoelectric materials such as n-type and p-type skutterudites with high thermoelectric figures-of-merit can include materials with filler atoms and/or materials formed by compacting particles (e.g., nanoparticles) into a material with a plurality of grains each having a portion having a skutterudite-based structure. Methods of forming thermoelectric skutterudites, which can include the use of hot press processes to consolidate particles, are also disclosed. The particles to be consolidated can be derived from (e.g., grinded from), skutterudite-based bulk materials, elemental materials, other non-Skutterudite-based materials, or combinations of such materials.

Synthesis and Thermoelectric Properties of Charge-Compensated SyPdxCo4-xSb12 Skutterudites.

PubMed

Wan, Shun; Qiu, Pengfei; Huang, Xiangyang; Song, Qingfeng; Bai, Shengqiang; Shi, Xun; Chen, Lidong

2018-01-10

Recently, the electronegative elements (e.g., S, Se, Cl, and Br) filled skutterudites have attracted great attention in thermoelectric community. Via doping of some electron donors at the Sb sites, these electronegative elements can be filled into the voids of CoSb 3 forming thermodynamically stable compounds, which greatly extends the scope of filled skutterudites. In this study, we show that doping appropriate elements at the Co sites can also stabilize the electronegative elements in the voids of CoSb 3 . A series of S y Pd x Co 4-x Sb 12 compounds were successfully fabricated by a traditional solid state reaction method combined with a spark plasma sintering technique. The phase composition and electrical and thermal transport properties were systematically characterized, and the related mechanisms were deeply discussed. It is found that the charge compensation between Pd doping and S filling is the main reason for the formation of thermodynamically stable S y Pd x Co 4-x Sb 12 compounds. Filling S element in the voids of CoSb 3 provides additional holes to reduce the carrier concentration while scarcely affecting the carrier mobility. However, doping Pd at the Co sites not only changes the carrier scattering mechanism but also deteriorates the carrier mobility. Low lattice thermal conductivities are observed in these S y Pd x Co 4-x Sb 12 compounds, which are attributed to the low resonant frequency of the S element. Finally, a maximal figure of merit of 0.85 is obtained for S 0.05 Pd 0.25 Co 3.75 Sb 12 at 700 K.

Modeling correlated motion in thermoelectric skutterudite materials

NASA Astrophysics Data System (ADS)

Keiber, Trevor; Bridges, Frank; Bridges Lab Team

2014-03-01

Filled skutterudite compounds, LnT4X12 (Ln=rare earth; T=Fe,Ru,Os; X=P,As,Sb), have previously been modeled using a rigid cage approximation for the ``rattling'' rare earth atom. The large thermal broadening with temperature of the rattler can be fit using an Einstein model. Recent measurements of the second neighbor Ln-T peaks show an unusually large thermal broadening suggesting motion of the cage of atoms. To incorporate these results we developed three and four mass spring models to give the acoustic and optical phonon mode spectra. For the simplest three mass model we identify the low energy optical mode as the rattling mode. This rattling mode is likely coupled to the acoustic mode, and responsible for the low thermal conductivity of the skutterudite compound. We extend this model to four atoms to describe the CuO4 rings in oxy-skutterudites and the X4 rings in LnT4X12. This talk provides a model for the experimental results of the previous presentation. Support: NSF DMR1005568.

Effects of partial La filling and Sb vacancy defects on CoS b 3 skutterudites

DOE PAGES

Hu, Chongze; Zeng, Xiaoyu; Liu, Yufei; ...

2017-04-25

Over the past decade, the open frame ("cagey") structure of CoSb 3 skutterudite has invited intensive filling studies with various rare-earth elements for delivering state-of-the-art mid-temperature thermoelectric performance. In order to rationalize previously reported experimental results and provide new insight into the underexplored roles of La fillers and Sb vacancies, ab initio density functional theory studies, along with semi-classical Boltzmann transport theory calculations, are performed for pristine CoSb 3 of different lattice settings and La-filled CoSb 3 with and without Sb s mono- and di-vacancy defects. We examine the effects of van der Waals (vdW) interactions, spin-orbit coupling (SOC), spinmore » polarization, partial La-filling, and Sb vacancy defects on the structural, electronic, and thermoelectric properties. The vdW interactions profoundly affect the lattice constant, which in turn affects the band gap. The SOC shows minor effects on the electronic and thermoelectric properties. The peculiar quasi-Dirac band in the pristine CoSb 3 largely survives La filling but not Sb vacancies, which instead introduce dispersive bands in the band gap region. Importantly, the band structure, density of states, and Fermi surface of La-filled CoSb 3 are significantly spin polarized, giving rise to spin-dependent thermoelectric properties. Seebeck coefficients directly calculated as a function of chemical potential are interpreted in connection with the electronic structures. Temperature-dependent Seebeck coefficients derived for the experimentally studied materials agree well with available experimental data. Seebeck coefficients obtained as a function of charge carrier concentration corroborate a thermoelectrically favorable role at high filling fractions played by the electron/hole pockets on the Fermi surface associated with the degenerate valleys/hills in the conduction/valence bands, respectively. Our results serve to advance the understanding of CoSb 3 skutterudite, a class of materials with important fundamental and application implications for thermoelectrics and spintronics.« less

Effects of partial La filling and Sb vacancy defects on CoS b 3 skutterudites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Chongze; Zeng, Xiaoyu; Liu, Yufei

Over the past decade, the open frame ("cagey") structure of CoSb 3 skutterudite has invited intensive filling studies with various rare-earth elements for delivering state-of-the-art mid-temperature thermoelectric performance. In order to rationalize previously reported experimental results and provide new insight into the underexplored roles of La fillers and Sb vacancies, ab initio density functional theory studies, along with semi-classical Boltzmann transport theory calculations, are performed for pristine CoSb 3 of different lattice settings and La-filled CoSb 3 with and without Sb s mono- and di-vacancy defects. We examine the effects of van der Waals (vdW) interactions, spin-orbit coupling (SOC), spinmore » polarization, partial La-filling, and Sb vacancy defects on the structural, electronic, and thermoelectric properties. The vdW interactions profoundly affect the lattice constant, which in turn affects the band gap. The SOC shows minor effects on the electronic and thermoelectric properties. The peculiar quasi-Dirac band in the pristine CoSb 3 largely survives La filling but not Sb vacancies, which instead introduce dispersive bands in the band gap region. Importantly, the band structure, density of states, and Fermi surface of La-filled CoSb 3 are significantly spin polarized, giving rise to spin-dependent thermoelectric properties. Seebeck coefficients directly calculated as a function of chemical potential are interpreted in connection with the electronic structures. Temperature-dependent Seebeck coefficients derived for the experimentally studied materials agree well with available experimental data. Seebeck coefficients obtained as a function of charge carrier concentration corroborate a thermoelectrically favorable role at high filling fractions played by the electron/hole pockets on the Fermi surface associated with the degenerate valleys/hills in the conduction/valence bands, respectively. Our results serve to advance the understanding of CoSb 3 skutterudite, a class of materials with important fundamental and application implications for thermoelectrics and spintronics.« less

Heavy fermions, quantum criticality, and unconventional superconductivity in filled skutterudites and related materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andraka, Bohdan

2015-05-14

The main goal of this program was to explore the possibility of novel states and behaviors in Pr-based system exhibiting quantum critical behavior, PrOs₄Sb₁₂. Upon small changes of external parameter, such as magnetic field, physical properties of PrOs₄Sb₁₂ are drastically altered from those corresponding to a superconductor, to heavy fermion, to field-induced ordered phase with primary quadrupolar order parameter. All these states are highly unconventional and not understood in terms of current theories thus offer an opportunity to expand our knowledge and understanding of condensed matter. At the same time, these novel states and behaviors are subjects to intense internationalmore » controversies. In particular, two superconducting phases with different transition temperatures were observed in some samples and not observed in others leading to speculations that sample defects might be partially responsible for these exotic behaviors. This work clearly established that crystal disorder is important consideration, but contrary to current consensus this disorder suppresses exotic behavior. Superconducting properties imply unconventional inhomogeneous state that emerges from unconventional homogeneous normal state. Comprehensive structural investigations demonstrated that upper superconducting transition is intrinsic, bulk, and unconventional. The high quality of in-house synthesized single crystals was indirectly confirmed by de Haas-van Alphen quantum oscillation measurements. These measurements, for the first time ever reported, spanned several different phases, offering unprecedented possibility of studying quantum oscillations across phase boundaries.« less

Theoretical investigations of electrical transport properties in CoSb3 skutterudites under hydrostatic loadings

DOE PAGES

Hu, Chongze; Ni, Peter; Zhan, Li; ...

2018-01-30

We report that CoSb 3-based skutterudites have been a benchmark mid-temperature thermoelectric material under intensive experimental and theoretical studies for decades. Doping and filling, to the first order, alter the crystal lattice constant of CoSb 3 in the context of “chemical pressure.” In this work, we employed ab initio density functional theory in conjunction with semiclassical Boltzmann transport theory to investigate the mechanical properties and especially how hydrostatic loadings, i.e., “physical pressure,” impact the electronic band structure, Seebeck coefficient, and power factor of pristine CoSb 3. It is found that hydrostatic pressure enlarges the band gap, suppresses the density ofmore » states (DOS) near the valence band edge, and fosters the band convergence between the valley bands and the conduction band minimum (CBM). By contrast, hydrostatic tensile reduces the band gap, increases the DOS near the valence band edge, and diminishes the valley bands near the CBM. Therefore, applying hydrostatic pressure provides an alternative avenue for achieving band convergence to improve thermoelectric properties of N-type CoSb 3, which is further supported by our carrier concentration studies. Lastly, these results provide valuable insight into the further improvement of thermoelectric performance of CoSb 3-based skutterudites via a synergy of physical and chemical pressures.« less

Electronegative Guests in CoSb 3

DOE PAGES

Duan, Bo; Yang, Jiong; Salvador, James R.; ...

2016-04-19

Introducing guests into a host framework to form a so called inclusion compound can be used to design materials with new and fascinating functionalities. The vast majority of inclusion compounds have electropositive guests with neutral or negatively charged frameworks. Here, we show a series of electronegative guest filled skutterudites with inverse polarity. The strong covalent guest-host interactions observed for the electronegative group VIA guests, i.e., S and Se, feature a unique localized cluster vibration which significantly influences the lattice dynamics, together with the point-defect scattering caused by element substitutions, resulting in very low lattice thermal conductivity values. The findings ofmore » electronegative guests provide a new perspective for guest-filling in skutterudites, and the covalent filler/lattice interactions lead to an unusual lattice dynamics phenomenon which can be used for designing high-efficiency thermoelectric materials and novel functional inclusion compounds with open structures.« less

Electronic and magnetic properties of quasi-skutterudite PrCo2Ga8 compound

NASA Astrophysics Data System (ADS)

Ogunbunmi, Michael O.; Sondezi, Buyisiwe M.; Nair, Harikrishnan S.; Strydom, André M.

2018-05-01

PrCo2Ga8 is an orthorhombic quasi-skutterudite type compound which crystallizes in the CaCo2Al8 structure type, with space group Pbam (No. 55). The Pr3+ ion has a site symmetry of Cs which predicts a crystal electric field (CEF) level splitting into 9 singlets for J = 4. However, a phase transition at Tm = 1.28 K is observed in electrical resistivity and specific heat results and is reported in this paper. The electrical resistivity shows an upturn below Tm due to the superzone-gap formation. This transition is tuneable in fields and is suppressed to lower temperatures with applied magnetic fields. The electronic specific heat Cp(T) / T increases below Tm and reaches a value of 7.37 J/(mol K2) at 0.4 K. The Sommerfeld coefficient, γ extracted from the low temperature analysis of C4f(T) / T is 637 mJ/(mol K2) indicating a possible mass enhancement of the quasiparticles. The calculated entropy value of 3.05 J/(mol K) is recovered around Tm exhibiting almost 53% of Rln2, where R is the universal gas constant. Magnetic susceptibility results obeys the Curie-Weiss law for data above 100 K with an estimated effective magnetic moment, μeff = 3.37 μB/Pr and Weiss temperature, θp = -124 K.

Changes in microstructure and physical properties of skutterudites after severe plastic deformation.

PubMed

Rogl, Gerda; Grytsiv, Andriy; Bursik, Jiri; Horky, Jelena; Anbalagan, Ramakrishnan; Bauer, Ernst; Mallik, Ramesh Chandra; Rogl, Peter; Zehetbauer, Michael

2015-02-07

The best p-type skutterudites with ZT > 1.1 so far are didymium (DD) filled, Fe/Co substituted, Sb-based skutterudites. DD0.68Fe3CoSb12 was prepared using an annealing-reacting-melting-quenching technique followed by ball milling and hot pressing. After severe plastic deformation via high-pressure torsion (HPT), no phase changes but particular structural variations were achieved, leading to modified transport properties with higher ZT values. Although after measurement-induced heating some of the HPT induced defects were annealed out, a still attractive ZT-value was preserved. In this paper we focus on explanations for these changes via TEM investigations, Raman spectroscopy and texture measurements. The grain sizes and dislocation densities, evaluated from TEM images, showed that (i) the majority of cracks generated during high-pressure torsion are healed during annealing, leaving only small pores, that (ii) the grains have grown, and that (iii) the dislocation density is decreased. While Raman spectra indicate that after HPT processing and annealing the vibration modes related to the shorter Sb-Sb bonds in the Sb4 rings are more affected than those related to the longer Sb-Sb bonds, almost no visible changes were observed in the pole intensity and/or orientation.

Dispersion of Multi-Walled Carbon Nanotubes in Skutterudites and Its Effect on Thermoelectric and Mechanical Properties.

PubMed

Schmitz, Andreas; Schmid, Carolin; de Boor, Johannes; Müller, Eckhard

2017-03-01

Filled cobalt-antimony based skutterudites have proven themselves as very promising thermoelectric materials for generator applications in an intermediate temperature range between 400 and 800 K due to their high figure of merit. Besides the functional thermoelectric properties also the skutterudites’ mechanical properties play an important role to withstand external mechanical and internal thermomechanical loads during operation. Properties of interest are hardness as well as fracture toughness and resistance to fatigue. Carbon nano tubes are well known for their high tensile strength and may therefore be used to increase the mechanical strength of composite materials. Additionally, the thermoelectric properties of the composite material might benefit from the high electrical conductivity of carbon nano tubes and increased phonon scattering at interfaces between matrix and carbon nano tube. A main precondition for benefiting from embedded nano-tubes is to achieve a homogeneous distribution of the CNTs and good adhesion between carbon nano tube and matrix material. In this work we present the influence of the introduction of multi-walled carbon nano tubes on the thermoelectric and mechanical properties of p-type skutterudites Ce(0.14)La(0.06)Co(2)Fe(2)Sb(12). The influence of different carbon nano tube concentrations and preparation routes on the resulting composite material’s thermoelectric, mechanical and microstructural properties is studied. A reduction of electrical and thermal conductivity as well as fracture strength is observed with increasing carbon nano tube content which is attributed to strong agglomeration of the nano tubes. The results underline the pivotal role of a homogeneous distribution of the carbon nano tubes for improving the mechanical properties of skutterudites.

Thermoelectric properties of Co(x)Ni(4-x)Sb(12-y)Sn(y) ternary skutterudites

NASA Technical Reports Server (NTRS)

Mackey, Jon A.; Dynys, Frederick W.; Sehirlioglu, Alp

2014-01-01

Thermoelectric materials based on the skutterudite crystal structure have demonstrated enhanced performance (ZT greater than 1), along with good thermal stability and favorable mechanical properties. Binary skutterudites, with single and multiple fillers, have been intensively studied in recent years. Compared to binary skutterudites, the ternary systems have received less attention, e.g. Ni4Sb8Sn4. Ternary skutterudites are isoelectronic variants of binary skutterudites; cation substitutions appear to be isostructural to their binary analogues. In general, ternary skutterudites exhibit lower thermal conductivity. Ternary systems of Ni4Bi8Ge4, Ni4Sb8Ge4, and Ni4Sb8Sn4 were investigated using combined solidification and sintering steps. Skutterudite formation was not achieved in the Ni4Bi8Ge4 and Ni4Sb8Ge4 systems; skutterudite formation occurred in Ni4Sb8Sn4 system. P-type material was achieved by Co substitution for Ni. Thermoelectric properties were measured from 298 K to 673 K for Ni4Sb8Sn4, Ni4 Sb7Sn5 and Co2Ni2Sb7Sn5. N-type Ni4Sb8Sn4 exhibit the highest figure of merit of 0.1 at 523 K.

FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shankar, A., E-mail: amitshan2009@gmail.com; Rai, D.P.; Chettri, Sandeep

2016-08-15

We have investigated the electronic structure, elastic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12} using the density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method within a framework of the generalized gradient approximation (GGA) approach is used to perform the calculations presented here. The electronic structure calculation suggests an indirect band gap semiconducting nature of the material with energy band gap of 0.08 eV. The analysis of the elastic constants at relaxed positions reveals the ductile nature of the sample material with covalent contribution in the inter-atomic bonding. The narrow band gap semiconductingmore » nature with high value of Seebeck coefficient suggests the possibility of the thermoelectric application of the material. The analysis of the thermal transport properties confirms the result obtained from the energy band structure of the material with high thermopower and dimensionless figure of merit 0.19 at room temperature.« less

Band Structure Engineering and Thermoelectric Properties of Charge-Compensated Filled Skutterudites

PubMed Central

Shi, Xiaoya; Yang, Jiong; Wu, Lijun; Salvador, James R.; Zhang, Cheng; Villaire, William L.; Haddad, Daad; Yang, Jihui; Zhu, Yimei; Li, Qiang

2015-01-01

Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co4Sb12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing the Yb content, we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively. PMID:26456013

Band structure engineering and thermoelectric properties of charge-compensated filled skutterudites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Xiaoya; Yang, Jiong; Wu, Lijun

2015-10-12

Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co 4Sb 12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing themore » Yb content, we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively.« less

Band Structure Engineering and Thermoelectric Properties of Charge-Compensated Filled Skutterudites

NASA Astrophysics Data System (ADS)

Shi, Xiaoya; Yang, Jiong; Wu, Lijun; Salvador, James R.; Zhang, Cheng; Villaire, William L.; Haddad, Daad; Yang, Jihui; Zhu, Yimei; Li, Qiang

2015-10-01

Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co4Sb12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing the Yb content, we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively.

Complex doping of group 13 elements In and Ga in caged skutterudite CoSb 3

DOE PAGES

Xi, Lili; Qiu, Yting; Zheng, Shang; ...

2014-12-12

The complex doping behavior of Ga and In in CoSb 3 has been investigated using ab initio total-energy calculations and thermodynamics. The formation energies of void filling, Sb substitution and complex dual-site occupancy defects with different charge states, and their dependence on chemical potentials of species, were studied. Results show that Ga predominantly forms dual-site 2Ga VF–Ga Sb defects and substitutes for Sb only at very high Fermi levels or electron concentrations. In, on the other hand, can play multiple roles in skutterudites, including filling in the crystalline voids, substituting for Sb atoms or forming dual-site occupancy, among which themore » fully charge-compensated dual-site defects (2In VF–In Sb and 4In VF–2In Sb) are dominant. The equilibrium concentration ratio of impurities at void-filling sites to those at Sb-substitution sites for Ga-doped CoSb 3 is very close to be 2:1, while this value markedly deviates from 2:1 for In-doped CoSb 3. Furthermore, the 2:1 ratio of Ga doping in CoSb 3 leads to low electron concentration (~2 × 10 19 cm –3) and makes the doped system a semiconductor.« less

Performance of Skutterudite-Based Modules

NASA Astrophysics Data System (ADS)

Nie, G.; Suzuki, S.; Tomida, T.; Sumiyoshi, A.; Ochi, T.; Mukaiyama, K.; Kikuchi, M.; Guo, J. Q.; Yamamoto, A.; Obara, H.

2017-05-01

Due to their excellent thermoelectric (TE) performance, skutterudite materials have been selected by many laboratories and companies for development of TE modules to recover power from waste heat at high temperatures (300°C to 600°C). After years of effort, we have developed reliable n- and p-type skutterudite materials showing maximum figure of merit ( ZT) of 1.0 at 550°C and 0.75 at 450°C, respectively. In this work, we systematically investigated the performance of a module made using these two kinds of skutterudite. We demonstrate ˜7.2% conversion efficiency for temperature of 600°C at the hot side of the module and 50°C at the cold side, and show that the module had excellent stability in the high-temperature environment. Further improving the TE performance of our skutterudites, the conversion efficiency reached ˜8.5% under the same condition.

Weak interband-coupling superconductivity in the filled skutterudite LaPt4Ge12

NASA Astrophysics Data System (ADS)

Zhang, J. L.; Pang, G. M.; Jiao, L.; Nicklas, M.; Chen, Y.; Weng, Z. F.; Smidman, M.; Schnelle, W.; Leithe-Jasper, A.; Maisuradze, A.; Baines, C.; Khasanov, R.; Amato, A.; Steglich, F.; Gumeniuk, R.; Yuan, H. Q.

2015-12-01

The superconducting pairing state of LaPt4Ge12 is studied by measuring the magnetic penetration depth λ (T ,B ) and superfluid density ρs(T ) using a tunnel-diode-oscillator (TDO)-based method and transverse-field muon-spin rotation (TF -μ SR ) spectroscopy. The penetration depth follows an exponential-type temperature dependence at T ≪Tc , but increases linearly with magnetic field at T =1.5 K. A detailed analysis demonstrates that both λL(T ) and ρsTDO(T ) , measured in the Meissner state using the TDO method, are well described by a two-gap γ model with gap sizes of Δ1(0 ) =1.31 kBTc and Δ2(0 ) =1.80 kBTc , and weak interband coupling. In contrast, ρsμ SR(T ) , derived from the μ SR data, can be fitted by a single-gap BCS model with a gap close to Δ2(0 ) . We conclude that LaPt4Ge12 is a marginal two-gap superconductor and the small gap Δ1 seems to be suppressed by a small magnetic field applied in the μ SR experiments. In comparison, the 4 f electrons in PrPt4Ge12 may enhance the interband coupling and, therefore, give rise to more robust multiband superconductivity.

Electronic and Transport Properties of LaNi4Sb12 Skutterudite: Modified Becke-Johnson Approach

NASA Astrophysics Data System (ADS)

Bhat, Tahir Mohiuddin; Singh, Srishti; Gupta, Dinesh C.

2018-05-01

We carried out an ab initio study of structural, electronic, thermodynamic, and thermoelectric properties of the lanthanum-filled skutterudite, LaNi4Sb12. Generalized gradient approximation and modified Becke-Johnson potentials were employed for the exchange-correlation potential. The electronic structure calculations display the metallic behavior of the compound. The alloy offers low lattice thermal conductivity along with a high Seebeck coefficient with a value of - 158 (μVK-1) at room temperature. The effect of high pressure and temperature on thermal properties like thermal expansion coefficient, heat capacity, and Grüneisen parameter are also investigated by means of a quasi-harmonic Debye model. The large Seebeck coefficient and high power factor exhibited by LaNi4Sb12 make it an attractive candidate for thermoelectric materials.

Thermoelectric properties of cobalt antimonide>-based skutterudites

NASA Astrophysics Data System (ADS)

Yang, Jian

Solid state cooling and power generation based on thermoelectric principles are regarded as one of the technologies with the potential of solving the current energy crisis. Thermoelectric devices could be widely used in waste heat recovery, small scale power generation and refrigeration. It has no moving parts and is environmental friendly. The limitation to its application is due to its low efficiency. Most of the current commercialized thermoelectric materials have figure of merit (ZT) around 1. To be comparable with kitchen refrigerator, ZT≃ 3 is required at room temperature. Skutterudites have emerged as member of the novel materials, which potentially have a higher ZT. In the dissertation, my investigation will be focused on the optimization of CoSb3-based skutterudites. Starting with Co and Sb elements, CoSb3 will form through a high energy ball mill. Unfortunately, even after 20 hours, only a small percentage of the powders have transformed in into CoSb3. Then the powders will be compacted into bulk samples by DC-controlled hot press. CoSb3 single phase will form after press. Characterization of the structure and thermoelectric properties will be presented with details. The effects of synthesis conditions on thermoelectric properties of skutterudites were studied and discussed. Several possible methods of improving the ZT of N type skutterudites were applied. The highest obtained ZT thus far is ˜1.2 from Yb doped CoSb3. For a group of samples with nominal composition YbxCo4Sb12, the increased Yb concentration in our samples not only enhanced the power factor due to electron doping effect but also decreased the thermal conductivity due to a stronger rattling effect. In addition, the increased grain boundary density per unit volume due to the small grains in our bulk skutterudite materials may have also helped to enhance the phonon scattering and thus to reduce the thermal conductivity. Single and double doping methods with different combinations were also tried. So far, none of them have surpassed ZT=1.2. Mixing different materials with Yb 0.35Co4Sb12 so far to increase the phonon scattering was also performed. No dramatic thermal conductivity reduction was observed. Small amounts of Fe/Mn substitution on Co sites will decrease the power factor to undesired degrees. Some results with Nd filled P type sample will be briefly introduced. P type samples are also obtained through substitution on Sb site. Preliminary work on preparing the electrode for CoSb3 will be presented in the dissertation. CoSi2 has low resistivity, and a similar coefficient of thermal expansion (CTE) as of doped CoSb3. It is good electrode candidate. DC-controlled hot press is used to make the contact. Thermal stability of the contact was tested. Small cracks will form in the contact area, further improvement is necessary. Finally, my previous work on ZnO nanowire growth is briefly introduced. Large throughput of ZnO nanowire could be obtained with NaCl as the support to promote the conversion of Zn powder to ZnO.

Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

DOE PAGES

Hu, Yanyun; Chen, Ning; Clancy, J. P.; ...

2017-12-29

We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

Local structure investigation of Ga and Yb dopants in Co4Sb12 skutterudites

NASA Astrophysics Data System (ADS)

Hu, Yanyun; Chen, Ning; Clancy, J. P.; Salvador, James R.; Kim, Chang-Yong; Shi, Xiaoya; Li, Qiang; Kim, Young-June

2017-12-01

We report comprehensive x-ray absorption spectroscopy studies at both the Ga K edge and Yb L2 edge to elucidate the local structure of Ga and Yb dopants in YbxGayCo4Sb12 . Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24 g site replacing Sb, and the other is the 2 a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2 a on-center site. At low concentrations of Yb, Ga24 g and Ga2 a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Funct. Mater. 23, 3194 (2013), 10.1002/adfm.201202571]. The Ga24 g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24 g site for the highest Yb concentration studied (x =0.4 ). In addition to the local structural evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K -edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga2 a to Ga24 g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co4Sb12 skutterudites is due to the increased Ga24 g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.

Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Yanyun; Chen, Ning; Clancy, J. P.

We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

Rattler behavior in As skutterudites and oxy-skutterudites

NASA Astrophysics Data System (ADS)

Bridges, Frank; Car, Brad; Hoffman-Stapleton, Mikaela; Keiber, Trevor; Sutton, Logan; Maple, M. Brian

2014-03-01

We report EXAFS measurements for the series CeX4As12 (X = Fe, Ru, Os) and NdCu3Ru4O12 as a function of temperature for most elements in the structure. In each case the rare earth atom is a ``rattler'' atom, with a low Einstein temperature while the skutterudite cage structure is relatively stiff. From temperature dependencies of the correlated Debye model for the cage atoms, one can estimate the effective spring constant for various atom pairs. We also find for the oxy-skutterudites that the planar CuO4 sub-structure is very stiff, and likely vibrates as a rigid unit. We compare the behavior of the As-skutterudites with other skutterudites and with the oxy-skutterudites, and discuss in terms of the rigid cage model. The second neighbor pair Ce-X for the As-skutterudites is softer than expected while for the oxy-skutterudites the second neighbor Nd-Ru pair is stiffer than the nearest neighbor Nd-O pair. Models are need to explore this behavior. Support: NSF DMR1005568.

Synthesis and thermoelectric properties of Nd-single filled p-type skutterudites

NASA Astrophysics Data System (ADS)

Wu, Hong; Shaheen, Nusrat; Yang, Heng-Quan; Peng, Kun-Ling; Shen, Xing-Chen; Wang, Guo-Yu; Lu, Xu; Zhou, Xiao-Yuan

2018-04-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11674040, 11404044, 51472036, 51672270, and 51401202), the Fundamental Research Funds for the Central Universities (Grant No. 106112016CDJZR308808), the 100 Talent Program of the Chinese Academy of Sciences (Grant No. 2013-46), and the Project for Fundamental and Frontier Research in Chongqing, China (Grant No. CSTC2015JCYJBX0026).

Solid Solutions Formation: Improving the Thermoelectric Properties of Skutterudites

NASA Technical Reports Server (NTRS)

Borshchevsky, A.; Caillat, T.; Fleurial, J. P.

1996-01-01

Materials with skutterudite structure have been known for a long time. Some of them are semiconductors. A typical skutterudite is CoSb(sub 3) and its thermoelectric properties were partially studied in the 1960's. Recently, it has been discovered that many skutterudite compounds are thermoelectrics with promising future.

Ba-filled Ni–Sb–Sn based skutterudites with anomalously high lattice thermal conductivity

DOE PAGES

Paschinger, W.; Rogl, Gerda; Grytsiv, A.; ...

2016-06-21

Here, in this study, novel filled skutterudites Ba yNi 4Sb 12-xSn x (y max = 0.93) have been prepared by arc melting followed by annealing at 250, 350 and 450°C up to 30 days in vacuum-sealed quartz vials. Extension of the homogeneity region, solidus temperatures and structural investigations were performed for the skutterudite phase in the ternary Ni–Sn–Sb and in the quaternary Ba–Ni–Sb–Sn systems. Phase equilibria in the Ni–Sn–Sb system at 450°C were established by means of Electron Probe Microanalysis (EPMA) and X-ray Powder Diffraction (XPD). With rather small cages Ni 4(Sb,Sn) 12, the Ba–Ni–Sn–Sb skutterudite system is perfectly suitedmore » to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni 4Sb 8.2Sn 3.8, Ba 0.42Ni 4Sb 8.2Sn 3.8 and Ba 0.92Ni 4Sb 6.7Sn 5.3 were used to measure their physical properties, i.e. temperature dependent electrical resistivity, Seebeck coefficient and thermal conductivity. The resistivity data demonstrate a crossover from metallic to semiconducting behaviour. The corresponding gap width was extracted from the maxima in the Seebeck coefficient data as a function of temperature. Single crystal X-ray structure analyses at 100, 200 and 300 K revealed the thermal expansion coefficients as well as Einstein and Debye temperatures for Ba 0.73Ni 4Sb 8.1Sn 3.9 and Ba 0.95Ni 4Sb 6.1Sn 5.9. These data were in accordance with the Debye temperatures obtained from the specific heat (4.4 K < T < 140 K) and Mössbauer spectroscopy (10 K < T < 290 K). Rather small atom displacement parameters for the Ba filler atoms indicate a severe reduction in the “rattling behaviour” consistent with the high levels of lattice thermal conductivity. The elastic moduli, collected from Resonant Ultrasonic Spectroscopy ranged from 100 GPa for Ni 4Sb 8.2Sn 3.8 to 116 GPa for Ba 0.92Ni 4Sb 6.7Sn 5.3. The thermal expansion coefficients were 11.8 × 10 -6 K -1 for Ni 4Sb 8.2Sn 3.8 and 13.8 × 10 -6 K -1 for Ba 0.92Ni 4Sb 6.7Sn 5.3. The room temperature Vickers hardness values vary within the range from 2.6 GPa to 4.7 GPa. Lastly, severe plastic deformation via high-pressure torsion was used to introduce nanostructuring; however, the physical properties before and after HPT showed no significant effect on the materials thermoelectric behaviour.« less

In-Filled La0.5Co4Sb12 Skutterudite System with High Thermoelectric Figure of Merit

NASA Astrophysics Data System (ADS)

Bashir, Mohamed Bashir Ali; Said, Suhana Mohd; Sabri, Mohd Faizul Mohd; Miyazaki, Yuzuru; Shnawah, Dhafer Abdulameer; Shimada, Masanori; Salleh, Mohd Faiz Mohd; Mahmood, Mohamad Syafie; Salih, Ethar Yahya; Fitriani, Fitriani; Elsheikh, Mohamed Hamid

2018-04-01

The contribution of In addition to the La0.5Co4Sb12 skutterudite structure to improve its thermoelectric properties has been demonstrated. In x La0.5Co4Sb12 (0 ≤ x ≤ 0.3) samples were prepared through mechanical alloying followed by spark plasma sintering. Characterization of the phase structure and morphology of the sintered In x La0.5Co4Sb12 bulk samples was carried out using x-ray diffraction (XRD) analysis, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Rietveld analysis of the XRD spectra indicated that double filling at the 2a (000) interstitial site with La and In was successfully achieved, significantly improving the thermoelectric performance of the La0.5Co4Sb12 compound through simultaneous increase in the electrical conductivity and Seebeck coefficient. A maximum power factor of 3.39 × 10-3 W/ m-K2 was recorded at 644 K for the In0.3La0.5Co4Sb12 sample, more than 96% of that of the La0.5Co4Sb12 sample. Double filling also effectively reduced the lattice thermal conductivity by about 46%, thus demonstrating that the overall improvement in ZT was primarily due to the reduced thermal conductivity. A maximum ZT value of 1.15 was achieved at 692 K for In0.3La0.5Co4Sb12.

Phonon conductivity metrics for compact, linked-cage, layered, and filled-cage crystals, using ab initio, molecular dynamics and Boltzmann transport treatments

NASA Astrophysics Data System (ADS)

Huang, Baoling

Atomic-level thermal transport in compact, layered, linked-cage, and filled-cage crystals is investigated using a multiscale approach, combines the ab initio calculation, molecular dynamics (MD), Boltzman transport equations (BTE), and the kinetic theory. These materials are of great interests in energy storage, transport, and conversion. The structural metrics of phonon conductivity of these crystals are then explored. An atomic structure-based model is developed for the understanding the relationship between the atomic structure and phonon transport in compact crystals at high temperatures. The elemental electronegativity, element mass, and the arrangement of bonds are found to be the dominant factors to determine the phonon conductivity. As an example of linked-cage crystals, the phonon conductivity of MOF-5 is investigated over a wide temperature range using MD simulations and the Green-Kubo method. The temperature dependence of the thermal conductivity of MOF-5 is found to be weak at high temperatures, which results from the suppression of the long-range acoustic phonon transport by the special linked-cage structure. The mean free path of the majority of phonons in MOF-5 is limited by the cage size. The phonon and electron transport in layered Bi2Te3 structure are investigated using the first-principle calculations, MD, and BTE. Strong anisotropy has been found for both phonon and electron transport due to the special layered structure. The long-range acoustic phonons dominate the phonon transport with a strong temperature and direction dependence. Temperature dependence of the energy gap and appropriate modelling of relaxation times are found to be important for the prediction of the electrical transport in the intrinsic regime. The scattering by the acoustic, optical, and polar-optical phonons are found to dominate the electron transport. For filled skutterudite structure, strong coupling between the filler and the host is found, which contradicts the traditional "rattler" concept. The interatomic bonds of the host are significantly affected by the filler. It is shown that without changing the interatomic potentials for the host, the filler itself can not result in a lower phonon conductivity for the filled structure. It is also found that the behavior of partially-filled skutterudites can be better understood by treating the partially-filled structure as a solid solution of the empty structure and fully-filled structure. The combination of theoretical-analysis methods used in this work, provides for comparative insight into the role of atomic structure on the phonon transport in a variety of crystals used in energy storage, transport, and conversion.

Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in; Priyadarshini, B.; Gopalan, R.

We report a significant reduction in the lattice thermal conductivity of the CoSb{sub 3} skuttertudites, doped with chalcogen atoms. Te/Se chalcogen atoms doped CoSb{sub 3} skutterudite samples (Te{sub 0.1}Co{sub 4}Sb{sub 12}, Se{sub 0.1}Co{sub 4}Sb{sub 12}, Te{sub 0.05}Se{sub 0.05}Co{sub 4}Sb{sub 12}) are processed by ball milling and spark plasma sintering. X-ray diffraction data combined with energy dispersive X-ray spectra indicate the doping of Te/Se chalcogen atoms in the skutterudite. The temperature dependent X-ray diffraction confirms the stability of the Te/Se doped CoSb{sub 3} skutterudite phase and absence of any secondary phase in the temperature range starting from 300 K to 773more » K. The Raman spectroscopy reveals that different chalcogen dopant atoms cause different resonant optical vibrational modes between the dopant atom and the host CoSb{sub 3} skutterudite lattice. These optical vibrational modes do scatter heat carrying acoustic phonons in a different spectral range. It was found that among the Te/Se chalcogen atoms, Te atoms alter the host CoSb{sub 3} skutterudite lattice vibrations to a larger extent than Se atoms, and can potentially scatter more Sb related acoustic phonons. The Debye model of lattice thermal conductivity confirms that the resonant phonon scattering has important contributions to the reduction of lattice thermal conductivity in CoSb{sub 3} skutterudites doped with Te/Se chalcogen atoms. Lattice thermal conductivity ∼ 0.9 W/mK at 773 K is achieved in Te{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites, which is the lowest value reported so far in CoSb{sub 3} skutterudites, doped with single Te chalcogen atom.« less

Analysis of Thermal Power Generation Capacity for a Skutterudite-Based Thermoelectric Functional Structure

NASA Astrophysics Data System (ADS)

Sun, Yajing; Chen, Gang; Bai, Guanghui; Yang, Xuqiu; Li, Peng; Zhai, Pengcheng

2017-05-01

Due to military or other requirements for hypersonic aircraft, the energy supply devices with the advantages of small size and light weight are urgently needed. Compared with the traditional energy supply method, the skutterudite-based thermoelectric (TE) functional structure is expected to generate electrical energy with a smaller structural space in the hypersonic aircraft. This paper mainly focuses on the responded thermal and electrical characteristics of the skutterudite-based TE functional structure (TEFS) under strong heat flux loads. We conduct TE simulations on the transient model of the TEFS with consideration of the heat flux loads and thermal radiation in the hot end and the cooling effect of the phase change material (PCM) in the cold end. We investigate several influential factors on the power generation capacity, such as the phase transition temperature of the PCM, the heat flux loads, the thickness of the TE materials and the thermal conductivity of the frame materials. The results show that better power generation capacity can be achieved with thicker TE materials, lower phase transition temperature and suitable thermal conductivity of the frame materials.

Lattice-dynamical model for the filled skutterudite LaFe4Sb12: Harmonic and anharmonic couplings

NASA Astrophysics Data System (ADS)

Feldman, J. L.; Singh, D. J.; Bernstein, N.

2014-06-01

The filled skutterudite LaFe4Sb12 shows greatly reduced thermal conductivity compared to that of the related unfilled compound CoSb3, although the microscopic reasons for this are unclear. We calculate harmonic and anharmonic force constants for the interaction of the La filler atom with the framework atoms. We find that force constants show a general trend of decaying rapidly with distance and are very small for the interaction of the La with its next-nearest-neighbor Sb and nearest-neighbor La. However, a few rather long-range interactions, such as with the next-nearest-neighbor La and with the third neighbor Sb, are surprisingly strong, although still small. We test the central-force approximation and find significant deviations from it. Using our force constants we calculate a bare La mode Gruneisen parameter and find a value of 3-4, substantially higher than values associated with cage atom anharmonicity, i.e., a value of about 1 for CoSb3 but much smaller than a previous estimate [Bernstein et al., Phys. Rev. B 81, 134301 (2010), 10.1103/PhysRevB.81.134301]. This latter difference is primarily due to the previously used overestimate of the La-Fe cubic force constants. We also find a substantial negative contribution to this bare La Gruneisen parameter from the aforementioned third-neighbor La-Sb interaction. Our results underscore the need for rather long-range interactions in describing the role of anharmonicity on the dynamics in this material.

Conversion efficiency of skutterudite-based thermoelectric modules.

PubMed

Salvador, James R; Cho, Jung Y; Ye, Zuxin; Moczygemba, Joshua E; Thompson, Alan J; Sharp, Jeffrey W; Koenig, Jan D; Maloney, Ryan; Thompson, Travis; Sakamoto, Jeffrey; Wang, Hsin; Wereszczak, Andrew A

2014-06-28

Presently, the only commercially available power generating thermoelectric (TE) modules are based on bismuth telluride (Bi2Te3) alloys and are limited to a hot side temperature of 250 °C due to the melting point of the solder interconnects and/or generally poor power generation performance above this point. For the purposes of demonstrating a TE generator or TEG with higher temperature capability, we selected skutterudite based materials to carry forward with module fabrication because these materials have adequate TE performance and are mechanically robust. We have previously reported the electrical power output for a 32 couple skutterudite TE module, a module that is type identical to ones used in a high temperature capable TEG prototype. The purpose of this previous work was to establish the expected power output of the modules as a function of varying hot and cold side temperatures. Recent upgrades to the TE module measurement system built at the Fraunhofer Institute for Physical Measurement Techniques allow for the assessment of not only the power output, as previously described, but also the thermal to electrical energy conversion efficiency. Here we report the power output and conversion efficiency of a 32 couple, high temperature skutterudite module at varying applied loading pressures and with different interface materials between the module and the heat source and sink of the test system. We demonstrate a 7% conversion efficiency at the module level when a temperature difference of 460 °C is established. Extrapolated values indicate that 7.5% is achievable when proper thermal interfaces and loading pressures are used.

Parametric Optimization of Thermoelectric Generators for Waste Heat Recovery

NASA Astrophysics Data System (ADS)

Huang, Shouyuan; Xu, Xianfan

2016-10-01

This paper presents a methodology for design optimization of thermoelectric-based waste heat recovery systems called thermoelectric generators (TEGs). The aim is to maximize the power output from thermoelectrics which are used as add-on modules to an existing gas-phase heat exchanger, without negative impacts, e.g., maintaining a minimum heat dissipation rate from the hot side. A numerical model is proposed for TEG coupled heat transfer and electrical power output. This finite-volume-based model simulates different types of heat exchangers, i.e., counter-flow and cross-flow, for TEGs. Multiple-filled skutterudites and bismuth-telluride-based thermoelectric modules (TEMs) are applied, respectively, in higher and lower temperature regions. The response surface methodology is implemented to determine the optimized TEG size along and across the flow direction and the height of thermoelectric couple legs, and to analyze their covariance and relative sensitivity. A genetic algorithm is employed to verify the globality of the optimum. The presented method will be generally useful for optimizing heat-exchanger-based TEG performance.

Fermi-surface topologies and low-temperature phases of the filled skutterudite compounds CeOs 4 Sb 12 and NdOs 4 Sb 12

DOE PAGES

Ho, Pei Chun; Singleton, John; Goddard, Paul A.; ...

2016-11-28

We use MHz conductivity, torque magnetometer, and magnetization measurements to report on single crystals of CeOs 4 Sb 12 and NdOs 4 Sb 12 using temperatures down to 0.5 K and magnetic fields of up to 60 tesla. The field-orientation dependence of the de Haas-van Alphen and Shubnikov-de Haas oscillations is deduced by rotating the samples about the [ 010 ] and [ 0more » $$\\bar{1}$$ 1 1 ] directions. Our results indicate that NdOs 4 Sb 12 has a similar Fermi surface topology to that of the unusual superconductor PrOs 4 Sb 12 , but with significantly smaller effective masses, supporting the importance of local phonon modes in contributing to the low-temperature heat capacity of NdOs 4 Sb 12 . By contrast, CeOs 4 Sb 12 undergoes a field-induced transition from an unusual semimetal into a high-field, high-temperature state characterized by a single, almost spherical Fermi-surface section. Furthermore, the behavior of the phase boundary and comparisons with models of the band structure lead us to propose that the field-induced phase transition in CeOs 4 Sb 12 is similar in origin to the well-known α - γ transition in Ce and its alloys.« less

Anomalous enhancement of the lower critical field deep in the superconducting state of LaRu4As12

NASA Astrophysics Data System (ADS)

Juraszek, J.; Bochenek, Ł.; Wawryk, R.; Henkie, Z.; Konczykowski, M.; Cichorek, T.

2018-05-01

LaRu4As12 with the critical temperature Tc = 10.4 K displays several features which point at a non-singlet superconducting order parameter, although the bcc crystal structure of the filled skutterudites does not favour the emergence of multiple energy gaps. LaRu4As12 displays an unexpected enhancement of the lower critical field deep in superconducting state which can be attributed to the existence of two superconducting gaps. At T = 0.4 K, the local magnetization measurements were performed utilizing miniaturized Hall sensors.

Role of working memory and lexical knowledge in perceptual restoration of interrupted speech.

PubMed

Nagaraj, Naveen K; Magimairaj, Beula M

2017-12-01

The role of working memory (WM) capacity and lexical knowledge in perceptual restoration (PR) of missing speech was investigated using the interrupted speech perception paradigm. Speech identification ability, which indexed PR, was measured using low-context sentences periodically interrupted at 1.5 Hz. PR was measured for silent gated, low-frequency speech noise filled, and low-frequency fine-structure and envelope filled interrupted conditions. WM capacity was measured using verbal and visuospatial span tasks. Lexical knowledge was assessed using both receptive vocabulary and meaning from context tests. Results showed that PR was better for speech noise filled condition than other conditions tested. Both receptive vocabulary and verbal WM capacity explained unique variance in PR for the speech noise filled condition, but were unrelated to performance in the silent gated condition. It was only receptive vocabulary that uniquely predicted PR for fine-structure and envelope filled conditions. These findings suggest that the contribution of lexical knowledge and verbal WM during PR depends crucially on the information content that replaced the silent intervals. When perceptual continuity was partially restored by filler speech noise, both lexical knowledge and verbal WM capacity facilitated PR. Importantly, for fine-structure and envelope filled interrupted conditions, lexical knowledge was crucial for PR.

Advanced thermoelectric materials with enhanced crystal lattice structure and methods of preparation

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

1998-01-01

New skutterudite phases including Ru.sub.0.5 Pd.sub.0.5 Sb.sub.3, RuSb.sub.2 Te, and FeSb.sub.2 Te, have been prepared having desirable thermoelectric properties. In addition, a novel thermoelectric device has been prepared using skutterudite phase Fe.sub.0.5 Ni.sub.0.5 Sb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using powder metallurgy techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities and good Seebeck coefficients. These materials have low thermal conductivity and relatively low electrical resistivity, and are good candidates for low temperature thermoelectric applications.

Thermoelectric Generators for Automotive Waste Heat Recovery Systems Part I: Numerical Modeling and Baseline Model Analysis

NASA Astrophysics Data System (ADS)

Kumar, Sumeet; Heister, Stephen D.; Xu, Xianfan; Salvador, James R.; Meisner, Gregory P.

2013-04-01

A numerical model has been developed to simulate coupled thermal and electrical energy transfer processes in a thermoelectric generator (TEG) designed for automotive waste heat recovery systems. This model is capable of computing the overall heat transferred, the electrical power output, and the associated pressure drop for given inlet conditions of the exhaust gas and the available TEG volume. Multiple-filled skutterudites and conventional bismuth telluride are considered for thermoelectric modules (TEMs) for conversion of waste heat from exhaust into usable electrical power. Heat transfer between the hot exhaust gas and the hot side of the TEMs is enhanced with the use of a plate-fin heat exchanger integrated within the TEG and using liquid coolant on the cold side. The TEG is discretized along the exhaust flow direction using a finite-volume method. Each control volume is modeled as a thermal resistance network which consists of integrated submodels including a heat exchanger and a thermoelectric device. The pressure drop along the TEG is calculated using standard pressure loss correlations and viscous drag models. The model is validated to preserve global energy balances and is applied to analyze a prototype TEG with data provided by General Motors. Detailed results are provided for local and global heat transfer and electric power generation. In the companion paper, the model is then applied to consider various TEG topologies using skutterudite and bismuth telluride TEMs.

TRMM Precipitation Radar Reflectivity Profiles Compared to High-Resolution Airborne and Ground-Based Radar Measurements

NASA Technical Reports Server (NTRS)

Heymsfield, G. M.; Geerts, B.; Tian, L.

1999-01-01

In this paper, TRMM (Tropical Rainfall Measuring Mission Satellite) Precipitation Radar (PR) products are evaluated by means of simultaneous comparisons with data from the high-altitude ER-2 Doppler Radar (EDOP), as well as ground-based radars. The comparison is aimed primarily at the vertical reflectivity structure, which is of key importance in TRMM rain type classification and latent heating estimation. The radars used in this study have considerably different viewing geometries and resolutions, demanding non-trivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems that are large relative to the PR footprint size, PR reflectivity profiles compare very well to high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright band height and rain types are accurate, even at high PR incidence angles. It was found that for, the PR reflectivity of convective cells small relative to the PR footprint is weaker than in reality. Some of these differences can be explained by non-uniform beam filling. For other cases where strong reflectivity gradients occur within a PR footprint, the reflectivity distribution is spread out due to filtering by the PR antenna illumination pattern. In these cases, rain type classification may err and be biased towards the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that the upper regions of precipitation systems remain undetected and that the PR storm top height estimate is unreliable, usually underestimating the actual storm top height. This applies to all cases but the discrepancy is larger for smaller cells where limited sensitivity is compounded by incomplete beam filling. Users of level three TRMM PR products should be aware of this scale dependency.

Evaluation of Thermoelectric Performance and Durability of Functionalized Skutterudite Legs

NASA Astrophysics Data System (ADS)

Skomedal, Gunstein; Kristiansen, Nils R.; Sottong, Reinhard; Middleton, Hugh

2017-04-01

Thermoelectric generators are a promising technology for waste heat recovery. As new materials and devices enter a market penetration stage, it is of interest to employ fast and efficient measurement methods to evaluate the long-term stability of thermoelectric materials in combination with metallization and coating (functionalized thermoelectric legs). We have investigated a method for measuring several thermoelectric legs simultaneously. The legs are put under a common temperature gradient, and the electrical characteristics of each leg are measured individually during thermal cycling. Using this method, one can test different types of metallization and coating applied to skutterudite thermoelectric legs and look at the relative changes over time. Postcharacterization of these initial tests with skutterudite legs using a potential Seebeck microprobe and an electron microscope showed that oxidation and interlayer diffusion are the main reasons for the gradual increase in internal resistance and the decrease in open-circuit voltage. Although we only tested skutterudite material in this work, the method is fully capable of testing all kinds of material, metallization, and coating. It is thus a promising method for studying the relationship between failure modes and mechanisms of functionalized thermoelectric legs.

Superstructure and physical properties of skutterudite-related phase CoGe1.5Se1.5

NASA Astrophysics Data System (ADS)

Liang, Y.; Fang, B.; Zhu, X. M.; Liang, M. M.

2017-03-01

CoGe1.5Se1.5 skutterudite-related phase with a homogeneity range has been synthesized by solid-state reaction. The phase purity, homogeneity range, crystal structure, thermal stability and electrical resistivity were studied. XRD data indicates that CoGe1.5Se1.5 crystallized in a modification of the skutterudite CoAs3 type structure with space group R\\bar{3} (a = b = 11.751(1) Å, c = 14.36(1) Å). HRTEM-SAED shows more information about the superstructure to confirm the rhombohedral symmetry with space group R\\bar{3}. The lattice parameter of this skutterudite-related phase was found to be dependent on the concentration of Ge and Se. CoGe1.5Se1.5 decomposed between 1073 K and 1173 K under argon atmosphere investigated by in-situ XRD, suggesting a good thermal stability. CoGe1.49Se1.42, CoGe1.43Se1.34 and CoGe1.50Se1.15 dense bulk samples were obtained by hot-press technique. The chemical composition detected by FESEM/EDS suggests the homogeneity range and the existence of voids at framework positions. The electrical resistivity of the compounds decreases with increasing temperature, acting as a semiconductor. The chemical composition has a big influence on the value of electrical resistivity and energy gap.

Measurement setup for the simultaneous determination of diffusivity and Seebeck coefficient in a multi-anvil apparatus

NASA Astrophysics Data System (ADS)

Jacobsen, M. K.; Liu, W.; Li, B.

2012-09-01

In this paper, a high pressure setup is presented for performing simultaneous measurements of Seebeck coefficient and thermal diffusivity in multianvil apparatus for the purpose of enhancing the study of transport phenomena. Procedures for the derivation of Seebeck coefficient and thermal diffusivity/conductivity, as well as their associated sources of errors, are presented in detail, using results obtained on the filled skutterudite, Ce0.8Fe3CoSb12, up to 12 GPa at ambient temperature. Together with recent resistivity and sound velocity measurements in the same apparatus, these developments not only provide the necessary data for a self-consistent and complete characterization of the figure of merit of thermoelectric materials under pressure, but also serve as an important tool for furthering our knowledge of the dynamics and interplay between these transport phenomena.

Measurement setup for the simultaneous determination of diffusivity and Seebeck coefficient in a multi-anvil apparatus.

PubMed

Jacobsen, M K; Liu, W; Li, B

2012-09-01

In this paper, a high pressure setup is presented for performing simultaneous measurements of Seebeck coefficient and thermal diffusivity in multianvil apparatus for the purpose of enhancing the study of transport phenomena. Procedures for the derivation of Seebeck coefficient and thermal diffusivity/conductivity, as well as their associated sources of errors, are presented in detail, using results obtained on the filled skutterudite, Ce(0.8)Fe(3)CoSb(12,) up to 12 GPa at ambient temperature. Together with recent resistivity and sound velocity measurements in the same apparatus, these developments not only provide the necessary data for a self-consistent and complete characterization of the figure of merit of thermoelectric materials under pressure, but also serve as an important tool for furthering our knowledge of the dynamics and interplay between these transport phenomena.

Ferrimagnetism in EuFe4Sb12 due to the interplay of f-electron moments and a nearly ferromagnetic host

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnamurthy, Vemuru; Lang, J. C.; Haskel, D.

2007-03-01

We combine x-ray magnetic circular dichroism spectroscopy at Fe L-2,L-3 edges, at Eu M-4,M-5 edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu0.95Fe4Sb12 is a ferrimagnet in which the Fe 3d moment and the Eu2+ 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L-3 edge XAS, we find that about 13% of the Eu have a formal valence of 3+. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T-C of 85 K in Eu0.95Fe4Sb12 to f-electron interaction with the nearly ferromagneticmore » [Fe4Sb12](2.2-) host lattice.« less

Low-energy inelastic response in the superconducting phases of PrOs4Sb12

NASA Astrophysics Data System (ADS)

Setty, Chandan; Wang, Yuxuan; Phillips, Philip W.

2017-08-01

Recent ac susceptibility and polar Kerr effect measurements in the skutterudite superconductor PrOs4Sb12 (POS) (E. M. Levenson-Falk, E. R. Schemm, M. B. Maple, and A. Kapitulnik, arXiv:1609.07535) uncovered the nature of the superconducting double transition from a high-temperature, high-field, time-reversal symmetric phase (or the A phase) to a low-temperature, low-field, time-reversal symmetry-broken phase (or the B phase). Starting from a microscopic model, we derive a Ginzburg-Landau expansion relevant to POS that describes this entrance into the time-reversal symmetry-broken phase along the temperature axis. We also provide a study of the low-energy inelastic (Raman) response in both the A and B phases of POS, and seek additional signatures which could help reveal the exact form of the gap functions previously proposed in these phases. By appropriately manipulating the incoming and scattered light geometries, along with additional subtraction procedures and suitable assumptions, we show that one can access the various irreducible representations contained in the point group describing POS. We demonstrate how to use this technique on example order parameters proposed in POS. Depending on whether there exist nodes along the c axis, we find additional low-energy spectral weight within the superconducting gap in the Eg geometry, a feature that could pinpoint the location of nodes on the Fermi surface.

Skutterudite Compounds For Power Semiconductor Devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre; Caillat, Thierry; Borshchevsky, Alexander; Vandersande, Jan

1996-01-01

New semiconducting materials with p-type carrier mobility values much higher than state-of-art semiconductors discovered. Nine compounds, antimonides CoSb(sub3), RhSb(sub3), IrSb(sub3), arsenides CoAs(sub3), RhAs(sub3), IrAs(sub3), and phosphides CoP(sub3), RhP(sub3) and IrP(sub3), exhibit same skutterudite crystallographic structure and form solid solutions of general composition Co(1-x-y)RH(x)Ir(y)P(1-w-z)As(w)Sb(z). Materials exhibit high hole mobilities, high doping levels, and high electronic figures of merit. Some compositions show great potential for application to thermoelectric devices.

Coating Thermoelectric Devices To Suppress Sublimation

NASA Technical Reports Server (NTRS)

Sakamoto, Jeffrey; Caillat, Thierry; Fleurial, Jean-Pierre; Snyder, G. Jeffrey

2007-01-01

A technique for suppressing sublimation of key elements from skutterudite compounds in advanced thermoelectric devices has been demonstrated. The essence of the technique is to cover what would otherwise be the exposed skutterudite surface of such a device with a thin, continuous film of a chemically and physically compatible metal. Although similar to other sublimation-suppression techniques, this technique has been specifically tailored for application to skutterudite antimonides. The primary cause of deterioration of most thermoelectric materials is thermal decomposition or sublimation - one or more elements sublime from the hot side of a thermoelectric couple, changing the stoichiometry of the device. Examples of elements that sublime from their respective thermoelectric materials are Ge from SiGe, Te from Pb/Te, and now Sb from skutterudite antimonides. The skutterudite antimonides of primary interest are CoSb3 [electron-donor (n) type] and CeFe(3-x)Co(x)Sb12 [electron-acceptor (p) type]. When these compounds are subjected to typical operating conditions [temperature of 700 C and pressure <10(exp -5) torr (0.0013 Pa)], Sb sublimes from their surfaces, with the result that Sb depletion layers form and advance toward their interiors. As the depletion layer advances in a given device, the change in stoichiometry diminishes the thermal-to-electric conversion efficiency of the device. The problem, then, is to prevent sublimation, or at least reduce it to an acceptably low level. In preparation for an experiment on suppression of sublimation, a specimen of CoSb3 was tightly wrapped in a foil of niobium, which was selected for its chemical stability. In the experiment, the wrapped specimen was heated to a temperature of 700 C in a vacuum of residual pressure <10(exp -5) torr (0.0013 Pa), then cooled and sectioned. Examination of the sectioned specimen revealed that no depletion layer had formed, indicating the niobium foil prevented sublimation of antimony at 700 C. This was a considerable improvement, considering that uncoated CoSb3 had been found to decompose to form the lowest antimonide at the surface at only 600 C. Evidently, because the mean free path of Sb at the given temperature and pressure was of the order of tens of centimeters, any barrier closer than tens of centimeters (as was the niobium foil) would have suppressed transport of Sb vapor, thereby suppressing sublimation of Sb

Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13 studied through specific heat and inelastic neutron scattering

NASA Astrophysics Data System (ADS)

Nair, Harikrishnan S.; Ogunbunmi, Michael O.; Ghosh, S. K.; Adroja, D. T.; Koza, M. M.; Guidi, T.; Strydom, A. M.

2018-04-01

Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr3Rh4Sn13 which crystallizes in the Yb3Rh4Sn13-type structure with a cage-like network of Sn atoms. In this structure, Pr3+ occupies a lattice site with D 2d point symmetry having a ninefold degeneracy corresponding to J  =  4. The magnetic susceptibility of Pr3Rh4Sn13 shows only a weak temperature dependence below 10 K otherwise remaining paramagnetic-like in the range, 10 K-300 K. From the inelastic neutron scattering intensity of Pr3Rh4Sn13 recorded at different temperatures, we identify excitations at 4.5(7) K, 5.42(6) K, 10.77(5) K, 27.27(5) K, 192.28(4) K and 308.33(3) K through a careful peak analysis. However, no signatures of long-range magnetic order are observed in the neutron data down to 1.5 K, which is also confirmed by the specific heat data down to 0.36 K. A broad Schottky-like peak is recovered for the magnetic part of the specific heat, C 4f, which suggests the role of crystal electric fields of Pr3+ . A crystalline electric field model consisting of 7 levels was applied to C 4f which leads to the estimation of energy levels at 4.48(2) K, 6.94(4) K, 11.23(8) K, 27.01(5) K, 193.12(6) K and 367.30(2) K. The CEF energy levels estimated from the heat capacity analysis are in close agreement with the excitation energies seen in the neutron data. The Sommerfeld coefficient estimated from the analysis of magnetic specific heat is γ = 761(6) mJ K-2 mol-Pr which suggests the formation of heavy itinerant quasi-particles in Pr3Rh4Sn13. Combining inelastic neutron scattering results, analysis of the specific heat data down to 0.36 K, magnetic susceptibility and, electrical and thermal transport, we establish the absence of long-range ordered magnetic ground state in Pr3Rh4Sn13.

Preparation and Some Properties of N-Type IrxCo1-xSB3 Solid Solutions

NASA Technical Reports Server (NTRS)

Caillat, Thierry

1995-01-01

A number of studies have been recently devoted to the preparation and characterization of binary skutterudite materials to investigate their potential as advanced thermoelectric materials. These studies show that the potential of these binary skutterudite compounds is limited because of their relatively large thermal conductivity. In order to achieve high thermoelectric figure of merits for these materials, efforts should focus on thermal conductivity reduction. Recent results obtained on n-type CoSb3 and IrSb3 compounds have shown that n-type skutterudite materials might have a better potential for thermoelectric applications than p-type materials. The thermoelectric properties of p-type IrxCo1-xSb3 solid solutions have been recently investigated and it was shown that a substantial reduction in thermal conductivity was achieved. We prepared and measured some properties of n-type IrxCo1-xSb3 solid solutions. The samples are characterized by large Seebeck coefficient values and significantly lower thermal conductivity values than those measured on the binary compounds CoSb3 and IrSb3. A maximum ZT value of about 0.4 was obtained at a temperature of about 300(deg)C. Improvements in the figure of merit are possible in this system by optimization of the doping level.

Preparation and Thermoelectric Properties of the Skutterudite-Related Phase Ru(0.5)Pd(0.5)Sb3

NASA Technical Reports Server (NTRS)

Caillat, T.; Kulleck, J.; Borshchevsky, A.; Fleurial, J.-P.

1996-01-01

A new skutterudite phase Ru(0.5)Pd(0.5)Sb3 was prepared. This new phase adds to a large number of already known materials with the skutterudite structure which have shown good potential for thermoelectric applications. Single phase, polycrystalline samples were prepared and characterized by x-ray analysis, electron probe microanalysis, density, sound velocity, thermal-expansion coefficient, and differential thermal analysis measurements. Ru(0.5)Pd(0.5)Sb3 has a cubic lattice, space group Im3 (T(sup 5, sub h)), with a = 9.298 A and decomposes at about 920 K. The Seebeck coefficient, the electrical resistivity, the Hall effect, and the thermal conductivity were measured on hot-pressed samples over a wide range of temperatures. Preliminary results show that Ru(0.5)Pd(0.5)Sb3 behaves as a heavily doped semiconductor with an estimated band gap of about 0.6 eV. The lattice thermal conductivity of Ru(0.5)Pd(0.5)Sb3 is substantially lower than that of the binary isostructural compounds CoSb3 and IrSb3. The unusually low thermal conductivity might be explained by additional hole and charge transfer phonon scattering in this material. The potential of this material for thermoelectric applications is discussed.

Mo/Ti Diffusion Bonding for Making Thermoelectric Devices

NASA Technical Reports Server (NTRS)

Sakamoto, Jeffrey; Kisor, Adam; Caillat, Thierry; Lara, Liana; Ravi, Vilupanur; Firdosy, Samad; Fleuiral, Jean-Pierre

2007-01-01

An all-solid-state diffusion bonding process that exploits the eutectoid reaction between molybdenum and titanium has been developed for use in fabricating thermoelectric devices based on skutterudite compounds. In essence, the process is one of heating a flat piece of pure titanium in contact with a flat piece of pure molybdenum to a temperature of about 700 C while pushing the pieces together with a slight pressure [a few psi (of the order of 10 kPa)]. The process exploits the energy of mixing of these two metals to form a strong bond between them. These two metals were selected partly because the bonds formed between them are free of brittle intermetallic phases and are mechanically and chemically stable at high temperatures. The process is a solution of the problem of bonding hot-side metallic interconnections (denoted hot shoes in thermoelectric jargon) to titanium-terminated skutterudite n and p legs during the course of fabrication of a unicouple, which is the basic unit cell of a thermoelectric device (see figure). The hot-side operating temperature required for a skutterudite thermoelectric device is 700 C. This temperature precludes the use of brazing to attach the hot shoe; because brazing compounds melt at lower temperatures, the hot shoe would become detached during operation. Moreover, the decomposition temperature of one of the skutterudite compounds is 762 C; this places an upper limit on the temperature used in bonding the hot shoe. Molybdenum was selected as the interconnection metal because the eutectoid reaction between it and the titanium at the ends of the p and n legs has characteristics that are well suited for this application. In addition to being suitable for use in the present bonding process, molybdenum has high electrical and thermal conductivity and excellent thermal stability - characteristics that are desired for hot shoes of thermoelectric devices. The process takes advantage of the chemical potential energy of mixing between molybdenum and titanium. These metals have a strong affinity for each other. They are almost completely soluble in each other and remain in the solid state at temperatures above the eutectoid temperature of 695 C. As a result, bonds formed by interdiffusion of molybdenum and titanium are mechanically stable at and well above the original bonding temperature of about 700 C. Inasmuch as the bonds are made at approximately the operating temperature, thermomechanical stresses associated with differences in thermal expansion are minimized.

Enhancement of thermoelectric performance with pressure in Ce0.8Fe3CoSb12.1

NASA Astrophysics Data System (ADS)

Jacobsen, M. K.; Liu, W.; Li, B.

2014-09-01

Transport properties (resistivity, thermal conductivity, and Seebeck coefficient) and sound velocities have been determined for the skutterudite Ce0.8Fe3CoSb12.1 with pressure up to 14 GPa. From these measurements, high pressure anomalous features were found in all transport properties. By correlating these with results from previous x-ray work, it has been determined that there is likely an electronic topological transition in this material induced by pressure. This is possibly due to the known pressure variation of valence in the void-filling Ce atom and has been found to induce an improved figure of merit at higher pressures, which shows a nearly two-fold increase with applied pressure. At higher pressures, it was determined that this anomalous behavior is suppressed and is possibly induced by insertion of Sb from the cage into the remaining central voids of the structure, similar to that seen in the CoSb3 parent compound.

Comprehensive Study of Pr-Doped GdBa2Cu3O7 - y System

NASA Astrophysics Data System (ADS)

Yamani, Z.; Akhavan, M.

1997-09-01

An extensive study of the magnetic, electrical transport, and structural properties of the normal and superconducting states of Gd1 - xPrxBa2Cu3O7 - y (GdPr-123) is presented. Ceramic compounds have been synthesized by the solid state reaction technique, and characterized by XRD, SEM, TGA, and DT techniques. The parent compound GdBa2Cu3O7 - y (Gd-123) is a high-Tc superconductor and the endpoint compound, PrBa2Cu3O7 - y (Pr-123) is a magnetic insulator, both having the crystal structures isomorphic to the 123 phase structure. The superconducting transition temperature is reduced with increasing Pr content in a non-linear manner, in contrast to the Abrikosov-Gorkov pair breaking theory. A metal-insulator transition is observed at the critical Pr content, xcr 0.45, at which superconductivity completely disappears. Magnetic susceptibility measurements show that the nominal Pr valence is 3.86+, independent of the Pr content. The metal-insulator transition in this system is similar to that in the oxygen-deficient RBa2Cu3O7 - y (R-123) system. Based on this resemblance, we suggest that Pr doping reduces the carrier concentration (either by hole filling/localization or changes in the band structure) similar to the deoxygenated case. Hence, the environment surrounding the Cu-O layers is important to high-Tc superconductivity (HTSC). In this sense, HTSC cannot completely be two dimensional feature. A chain-plane correlation (CPC) effect is plausible. The normal state conduction mechanism has been interpreted by the quantum percolation theory based on localized states. Localization is probably caused by the Pr valence fluctuations in the GdPr-123 system.

Complex vibrations in arsenide skutterudites and oxyskutterudites

NASA Astrophysics Data System (ADS)

Bridges, F.; Car, B.; Sutton, L.; Hoffman-Stapleton, M.; Keiber, T.; Baumbach, R. E.; Maple, M. B.; Henkie, Z.; Wawryk, R.

2015-01-01

The local structure of two skutterudite families—Ce M4As12 (M =Fe , Ru, Os) and L n Cu3Ru4O12 (L n =La , Pr, and Nd)—have been studied using the extended x-ray absorption fine structure (EXAFS) technique with a focus on the lattice vibrations about the rare-earth "rattler atoms" and the extent to which these vibrations can be considered local modes, with the rattler vibrating inside a nearly rigid cage. X-ray absorption data at all the metal edges were collected over a temperature range of 4 to 300 K and analyzed using standard procedures. The pair distances from EXAFS results agree quite well with the average structure obtained from diffraction. The cage structure is formed by the M and As atoms in Ce M4As12 and by Cu, O, and Ru atoms in L n Cu3Ru4O12 . Although some of the bonds within the cage are quite stiff (correlated Debye temperatures, θcD, are ˜500 K for Ce M4As12 and above 800 K for L n Cu3Ru4O12 ), we show that the structure is not completely rigid. For the rattler atom the nearest-neighbor pairs have a relatively low Einstein temperature, θE:˜100 - 120 K for Ce-As and ˜130 K for L n -O . Surprisingly, the behaviors of the second-neighbor pairs are quite different: for Ce M4As12 the second-neighbor pairs (Ce -M ) have a weaker bond while for L n Cu3Ru4O12 the L n -Ru second-neighbor pair has a stiffer effective spring constant than the first-neighbor pair. In addition, we show that the As4 or CuO4 rings are relatively rigid units and that their vibrations are anisotropic within these cubic structures, with stiff restoring forces perpendicular to the rings and much weaker restoring forces in directions parallel to the rings. Consequently vibrations of the rings may also act as "rattlers" and help suppress thermal conductivity. In general neither the rigid-cage approximation nor the simple reduced-mass approximation are sufficient for describing rattler behavior.

A Chemical Understanding of the Band Convergence in Thermoelectric CoSb 3 Skutterudites: Influence of Electron Population, Local Thermal Expansion, and Bonding Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanus, Riley; Guo, Xingyu; Tang, Yinglu

2017-01-13

N-Type skutterudites, such as Yb xCo 4Sb 12, have recently been shown to exhibit high valley degeneracy with possible band convergence, explaining the excellent thermoelectric efficiency of these materials. Using a combined theoretical and experimental approach involving temperature-dependent synchrotron diffraction, molecular orbital diagrams, and computational studies, the chemical nature of critical features in the band structure is highlighted. We identify how n-type doping on the filler site induces structural changes that are observed in both the diffraction data and computational results. Additionally, we show how chemical n-type doping slightly alters the electronic band structure, moving the high-valley degeneracy secondary conductionmore » band closer to the primary conduction band and thus inducing band convergence.« less

Nanostructured Co1-xNix(Sb1-yTey)3 skutterudites: Theoretical modeling, synthesis and thermoelectric properties

NASA Astrophysics Data System (ADS)

Stiewe, Christian; Bertini, Luca; Toprak, Muhammet; Christensen, Mogens; Platzek, Dieter; Williams, Simon; Gatti, Carlo; Müller, Eckhard; Iversen, Bo B.; Muhammed, Mamoun; Rowe, Michael

2005-02-01

The properties of Te-doped Co(Sb1-yTey)3 and Te-Ni double-doped Co1-xNix(Sb1-yTey)3 nanostructured skutterudites were evaluated by means of x-ray powder diffraction, and transport properties measured on the synthesized samples have been compared with ab initio theoretical modeling. Theoretical optimal dopant contents have been evaluated according to the maximum value of the power factor, calculating the electronic transport properties from the ab initio material band structure using semiclassical Boltzmann transport theory. The samples have been synthesized by chemical alloying with Te substitution for Sb up to 2.5at.% and Ni substitution for Co up to 2.0at.%. X-ray powder diffraction has been performed on all samples to reveal information about phase purity and Rietveld refinement was performed for the phase composition and cell parameter. The thermoelectric properties of the resulting consolidates were investigated in a temperature range from 300to723K using various measurement facilities. A standardization and round robin program was started among the participating evaluation laboratories in order to ensure reliability of the data obtained. The significant reduction in thermal conductivity, when compared to highly annealed CoSb3, could be proved which is caused by the nanostructuring, resulting in a high concentration of grain boundaries. A combination of substitution levels for Ni and Te has been found resulting in the largest ZT value of 0.65 at 680K among unfilled skutterudite materials.

Liquid-Metal Pump Technologies for Nuclear Surface Power

NASA Technical Reports Server (NTRS)

Polzin, K. A.

2007-01-01

Multiple liquid-metal pump options are reviewed for the purpose of determining the technologies that are best suited for inclusion in a nuclear reactor thermal simulator intended to test prototypical space nuclear system components. Conduction, induction, and thermoelectric electromagnetic pumps are evaluated based on their performance characteristics and the technical issues associated with incorporation into a reactor system. The thermoelectric pump is recommended for inclusion in the planned system at NASA MSFC based on its relative simplicity, low power supply mass penalty, flight heritage, and the promise of increased pump efficiency over earlier flight pump designs through the use of skutterudite thermoelectric elements.

76 FR 77479 - Foreign-Trade Zone 7-Mayaguez, PR; Application for Temporary/Interim Manufacturing Authority...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-13

... (Pharmaceutical and Nutritional Intravenous Bags and Administration Sets); Aibonito and Jayuya, PR An application... Baxter facilities (200 million unit capacity) are used for the manufacture of pharmaceutical and... authority to produce filled pharmaceutical and nutritional I.V. bags (HTSUS 3004.20, 3004.40, 3004.50, 3004...

Thermoelectric properties of the unfilled skutterudite FeSb 3 from first principles and Seebeck local probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemal, Sébastien; Nguyen, Ngoc; de Boor, Johannes

2015-11-16

In this paper, using a combination of first-principles calculations and experimental transport measurements, we study the electronic and magnetic structure of the unfilled skutterudite FeSb 3. We employ the hybrid functional approach for exchange correlation. The ground state is determined to be antiferromagnetic with an atomic magnetic moment of 1.6μ B/Fe. The Néel temperature T N is estimated at 6 K, in agreement with experiments which found a paramagnetic state down to 10 K. The ground state is semiconducting, with a small electronic gap of 33meV, also consistent with previous experiments on films. Charge carrier concentrations are estimated from Hallmore » resistance measurements. The Seebeck coefficient is measured and mapped using a scanning probe at room temperature that yields an average value of 38.6μVK -1, slightly lower than the theoretical result. Finally, the theoretical conductivity is analyzed as a function of temperature and concentration of charge carriers.« less

PREFACE: Preface

NASA Astrophysics Data System (ADS)

Hotta, Takashi

2016-02-01

This volume of Journal of Physics: Conference Series contains both invited and contributed papers presented at the International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure", which was held from 24-25 September 2015 at the Minami-Osawa Campus of Tokyo Metropolitan University (TMU). The Graduate School of Science and Engineering of TMU is now promoting a research project on "New Quantum Phases Emerging from Novel Crystal Structure" with the support of the university. This is the cooperative project involving the electrical and electronic engineering and physics departments to discover new quantum phases in strongly correlated electron systems on novel crystal structures, with geometrically characteristic properties such as cage, layered, and geometrical frustrated structures. In this international symposium, we have mainly picked up BiS2-based layered superconductors, cage-structure materials such as 1-2-20 and filled skutterudites, geometrically frustrated systems such as pyrochlore compounds, and noncentrosymmetric materials. Topics on other materials with exotic crystal structure have been also discussed. I believe that this symposium provides a good opportunity to present recent research results on magnetism and superconductivity in such materials, and to discuss future directions of research on strongly correlated electron systems with novel crystal structure. I would like to give thanks, on behalf of the organizing committee, to all participants of the TMU International Symposium and all members of the Advisory Committee, who have contributed to the success of this symposium. I further thank the TMU Research Organization for the financial support of this symposium.

Liquid Metal Pump Technologies for Nuclear Surface Power

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.

2007-01-01

Multiple liquid metal pump options are reviewed for the purpose of determining the technologies that are best suited for inclusion in a nuclear reactor thermal simulator intended to rest prototypical space nuclear surface power system components. Conduction, induction and thermoelectric electromagnetic pumps are evaluated based on their performance characteristics and the technical issues associated with incorporation into a reactor system. A thermoelectric electromagnetic pump is selected as the best option for use in NASA-MSFC's Fission Surface Power-Primary Test Circuit reactor simulator based on its relative simplicity, low power supply mass penalty, flight heritage, and the promise of increased pump efficiency over those earlier pump designs through the use of skutterudite thermoelectric elements.

Part-crystalline part-liquid state and rattling-like thermal damping in materials with chemical-bond hierarchy

DOE PAGES

Qiu, Wujie; Xi, Lili; Wei, Ping; ...

2014-10-06

Understanding thermal and phonon transport in solids has been of great importance in many disciplines such as thermoelectric materials, which usually requires an extremely low lattice thermal conductivity (LTC). Here, by analyzing the finite-temperature structural and vibrational characteristics of typical thermoelectric compounds such as filled skutterudites and Cu 3SbSe 3, we demonstrate a concept of part-crystalline part-liquid state in the compounds with chemical-bond hierarchy, in which certain constituent species weakly bond to other part of the crystal. Such a material could intrinsically manifest the coexistence of rigid crystalline sublattices and other fluctuating noncrystalline sublattices with thermally induced large-amplitude vibrations andmore » even flow of the group of species atoms, leading to atomic-level heterogeneity, mixed part-crystalline part-liquid structure, and thus rattling-like thermal damping due to the collective soft-mode vibrations similar to the Boson peak in amorphous materials. Lastly, the observed abnormal LTC close to the amorphous limit in these materials can only be described by an effective approach that approximately treats the rattling-like damping as a “resonant” phonon scattering.« less

Le premier examen gynécologique idéal imaginé par les jeunes filles

PubMed Central

Freyens, Anne; Dejeanne, Mélanie; Fabre, Elise; Rouge-Bugat, Marie-Eve; Oustric, Stéphane

2017-01-01

Résumé Objectif Explorer les représentations sur l’examen gynécologique (EG) et identifier les critères nécessaires à son bon déroulement chez des adolescentes n’ayant pas encore vécu cet examen. Type d’étude Enquête qualitative par entrevues semi-dirigées. Contexte Midi-Pyrénées (France) et Auvergne (France). Participants Jeunes filles de 15 à 19 ans qui n’ayant pas vécu l’EG. Méthodes Le mode de recrutement de l’échantillon a été double : sélection des jeunes filles par la technique boule-de-neige et sélection par la technique d’échantillonnage ciblé jusqu’à l’obtention de la saturation des données tout en cherchant la variation maximale dans les profils des sujets. Les questions ouvertes portaient sur les sources d’informations, les connaissances, les critères de bon déroulement et l’imaginaire autour de l’EG. Le verbatim a fait l’objet d’une analyse longitudinale immédiate rassemblant le contexte (notes des chercheurs) et les idées principales de l’entretien. Une analyse transversale thématique a été réalisée. Principales constatations Une méconnaissance générale des jeunes filles sur l’EG entretenait l’imaginaire autour de cet examen perçu comme obligatoire. L’EG idéal, selon les jeunes filles interrogées, aurait lieu chez une jeune fille qui se sentirait prête, informée préalablement, pouvant être accompagnée selon son souhait. Cet examen se déroulerait dans un environnement chaleureux et confortable afin de diminuer le sentiment de vulnérabilité. La qualité du lien avec le médecin conditionnerait l’acceptation de cet examen par les jeunes filles. Conclusion Une consultation dédiée à l’information, préalable à la consultation où a lieu l’EG, permettrait de diminuer les appréhensions, d’améliorer les connaissances des jeunes filles et de favoriser le bon déroulement du futur premier EG tant pour le médecin que pour la patiente. PMID:28807971

Value redefined for inflammatory bowel disease patients: a choice-based conjoint analysis of patients' preferences.

PubMed

van Deen, Welmoed K; Nguyen, Dominic; Duran, Natalie E; Kane, Ellen; van Oijen, Martijn G H; Hommes, Daniel W

2017-02-01

Value-based healthcare is an upcoming field. The core idea is to evaluate care based on achieved outcomes divided by the costs. Unfortunately, the optimal way to evaluate outcomes is ill-defined. In this study, we aim to develop a single, preference based, outcome metric, which can be used to quantify overall health value in inflammatory bowel disease (IBD). IBD patients filled out a choice-based conjoint (CBC) questionnaire in which patients chose preferable outcome scenarios with different levels of disease control (DC), quality of life (QoL), and productivity (Pr). A CBC analysis was performed to estimate the relative value of DC, QoL, and Pr. A patient-centered composite score was developed which was weighted based on the stated preferences. We included 210 IBD patients. Large differences in stated preferences were observed. Increases from low to intermediate outcome levels were valued more than increases from intermediate to high outcome levels. Overall, QoL was more important to patients than DC or Pr. Individual outcome scores were calculated based on the stated preferences. This score was significantly different from a score not weighted based on patient preferences in patients with active disease. We showed the feasibility of creating a single outcome metric in IBD which incorporates patients' values using a CBC. Because this metric changes significantly when weighted according to patients' values, we propose that success in healthcare should be measured accordingly.

The promises and challenges of pre-exposure prophylaxis as part of the emerging paradigm of combination HIV prevention.

PubMed

Cáceres, Carlos F; Koechlin, Florence; Goicochea, Pedro; Sow, Papa-Salif; O'Reilly, Kevin R; Mayer, Kenneth H; Godfrey-Faussett, Peter

2015-01-01

Towards the end of the twentieth century, significant success was achieved in reducing incidence in several global HIV epidemics through ongoing prevention strategies. However, further progress in risk reduction was uncertain. For one thing, it was clear that social vulnerability had to be addressed, through research on interventions addressing health systems and other structural barriers. As soon as antiretroviral treatment became available, researchers started to conceive that antiretrovirals might play a role in decreasing either susceptibility in uninfected people or infectiousness among people living with HIV. In this paper we focus on the origin, present status, and potential contribution of pre-exposure prophylaxis (PrEP) within the combination HIV prevention framework. After a phase of controversy, PrEP efficacy trials took off. By 2015, daily oral PrEP, using tenofovir alone or in combination with emtricitabine, has been proven efficacious, though efficacy seems heavily contingent upon adherence to pill uptake. Initial demonstration projects after release of efficacy results have shown that PrEP can be implemented in real settings and adherence can be high, leading to high effectiveness. Despite its substantial potential, beliefs persist about unfeasibility in real-life settings due to stigma, cost, adherence, and potential risk compensation barriers. The strategic synergy of behavioural change communication, biomedical strategies (including PrEP), and structural programmes is providing the basis for the combination HIV prevention framework. If PrEP is to ever become a key component of that framework, several negative beliefs must be confronted based on emerging evidence; moreover, research gaps regarding PrEP implementation must be filled, and appropriate prioritization strategies must be set up. Those challenges are significant, proportional to the impact that PrEP implementation may have in the global response to HIV.

The promises and challenges of pre-exposure prophylaxis as part of the emerging paradigm of combination HIV prevention

PubMed Central

Cáceres, Carlos F; Koechlin, Florence; Goicochea, Pedro; Sow, Papa-Salif; O'Reilly, Kevin R; Mayer, Kenneth H; Godfrey-Faussett, Peter

2015-01-01

Introduction Towards the end of the twentieth century, significant success was achieved in reducing incidence in several global HIV epidemics through ongoing prevention strategies. However, further progress in risk reduction was uncertain. For one thing, it was clear that social vulnerability had to be addressed, through research on interventions addressing health systems and other structural barriers. As soon as antiretroviral treatment became available, researchers started to conceive that antiretrovirals might play a role in decreasing either susceptibility in uninfected people or infectiousness among people living with HIV. In this paper we focus on the origin, present status, and potential contribution of pre-exposure prophylaxis (PrEP) within the combination HIV prevention framework. Discussion After a phase of controversy, PrEP efficacy trials took off. By 2015, daily oral PrEP, using tenofovir alone or in combination with emtricitabine, has been proven efficacious, though efficacy seems heavily contingent upon adherence to pill uptake. Initial demonstration projects after release of efficacy results have shown that PrEP can be implemented in real settings and adherence can be high, leading to high effectiveness. Despite its substantial potential, beliefs persist about unfeasibility in real-life settings due to stigma, cost, adherence, and potential risk compensation barriers. Conclusions The strategic synergy of behavioural change communication, biomedical strategies (including PrEP), and structural programmes is providing the basis for the combination HIV prevention framework. If PrEP is to ever become a key component of that framework, several negative beliefs must be confronted based on emerging evidence; moreover, research gaps regarding PrEP implementation must be filled, and appropriate prioritization strategies must be set up. Those challenges are significant, proportional to the impact that PrEP implementation may have in the global response to HIV. PMID:26198341

Trabecular Bone Strength Predictions of HR-pQCT and Individual Trabeculae Segmentation (ITS)-Based Plate and Rod Finite Element Model Discriminate Postmenopausal Vertebral Fractures

PubMed Central

Liu, X. Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X. Edward

2013-01-01

While high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (μFE) prediction of yield strength by HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high resolution μCT voxel model of 19 trabecular sub-volumes from human cadaveric tibiae samples. Both Young’s modulus and yield strength of HR-pQCT PR models strongly correlated with those of μCT voxel models (r2=0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and CPU time (>1,200-fold). Then, we applied PR model μFE analysis to HR-pQCT images of 60 postmenopausal women with (n=30) and without (n=30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young’s modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for aBMD T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against μCT voxel models and demonstrated its ability to discriminate vertebral fracture status in postmenopausal women. This accurate nonlinear μFE prediction of HR-pQCT PR model, which requires only seconds of desktop computer time, has tremendous promise for clinical assessment of bone strength. PMID:23456922

Synthesis and thermoelectric properties of CoP(sub 3)

NASA Technical Reports Server (NTRS)

Shields, V. B.; Caillet, T.

2002-01-01

In an effort to expand the range of operation for highly efficient, segmented thermoelectric unicouples currently being developed at JPL, skutterudite phosphides are being investigated as potential high temperature segments to supplement antimonide segments that limit the use of these unicouples at a hot-side temperature of about 873-973 K.

Semiconductor apparatus utilizing gradient freeze and liquid-solid techniques

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

1998-01-01

Transition metals of Group VIII (Co, Rh and Ir) have been prepared as semiconductor compounds with the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freezing techniques and/or liquid phase sintering techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 1200 cm.sup.2.V.sup.-1.s.sup.-1) and good Seebeck coefficients (up to 150 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a substantial increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

A TiAlCu Metallization for ` n' Type CoSb_x Skutterudites with Improved Performance for High-Temperature Energy Harvesting Applications

NASA Astrophysics Data System (ADS)

Rao, Ashwin; Bosak, Gregg; Joshi, Binay; Keane, Jennifer; Nally, Luke; Peng, Adam; Perera, Susanthri; Waring, Alfred; Poudel, Bed

2017-04-01

The choice of the appropriate metallizing layer for high-temperature thermoelectric (TE) materials is a tricky task and poses varied challenges to researchers. In this work, a n type TiAl metallizing layer (90% Ti with 10% Al by weight with a copper foil) is proposed for a Yb_{0.2}Co4Sb_{12} skutterudite (SK) TE material coupled with a standard ` p type' SK base of Nd_{0.45}Ce_{0.45}Fe_{3.5}Co_{0.5}Sb_{12} with a 60:12:28% Fe:Ni:Cr metallizing layer. The n type and p type nanostructured SK powders are sintered at high temperatures and pressures in a DC hot press from which a TE device is assembled using diced, polished and property characterized TE legs (high figure of merit zT of 1.4 for n type and 1.2 for p type, respectively). The device is evaluated for functional degradation with repeated cycling to 500°C hot side (HS) and 50°C cold side (CS) temperatures in a specially designed high-vacuum test rig with key TE properties like peak power, open circuit voltage, and material internal resistance continuously recorded over each cycle. The device shows stable performance with <7% drop in TE harvested power over 2500 thermal cycles. With the industry benchmark for evaluating TE device performance being around 1000 thermal cycles (<10% drop in TE power over time), the study indicates stable performance of the n type TiAl metallizing layer over the device lifetime.

The 7 × 1 Fermi Surface Reconstruction in a Two-dimensional f -electron Charge Density Wave System: PrTe 3

DOE PAGES

Lee, Eunsook; Kim, D. H.; Kim, Hyun Woo; ...

2016-07-25

The electronic structure of a charge density wave (CDW) system PrTe 3 and its modulated structure in the CDW phase have been investigated by employing ARPES, XAS, Pr 4 f RPES, and first-principles band structure calculation. Pr ions are found to be nearly trivalent, supporting the CDW instability in the metallic Te sheets through partial filling. Finite Pr 4 f spectral weight is observed near the Fermi level, suggesting the non-negligible Pr 4 f contribution to the CDW formation through the Pr 4 f -Te 5p hybridization. The two-fold symmetric features in the measured Fermi surface (FS) of PrTe 3more » are explained by the calculated FS for the assumed 7 × 1 CDW supercell formation in Te sheets. The shadow bands and the corresponding very weak FSs are observed, which originate from both the band folding due to the 3D interaction of Te sheets with neighboring Pr-Te layers and that due to the CDW-induced FS reconstruction. The straight vertical FSs are observed along k z, demonstrating the nearly 2D character for the near-EF states. The observed linear dichroism reveals the in-plane orbital character of the near-E F Te 5p states.« less

Buoyancy compensation of juvenile chinook salmon implanted with two different size dummy transmitters

USGS Publications Warehouse

Perry, R.W.; Adams, N.S.; Rondorf, D.W.

2001-01-01

We investigated the effect of two different sizes of surgically implanted transmitters on the buoyancy compensation of juvenile chinook salmon Oncorhynchus tshawytscha. We determined buoyancy by measuring the density of fish with a filled air bladder in graded salinity baths. In addition, we examined the effect of pressure changes on buoyancy by measuring the pressure reduction (PR) at which fish became neutrally buoyant. We found no significant difference between the density of control and tagged groups, indicating that fish were able to compensate for the transmitter by filling their air bladders. However, both groups of tagged fish had significantly lower PR than control fish. Regression analysis of fish density on PR indicated that density of the tagged groups changed at a higher rate than that of the controls. As a result, tagged fish attained neutral buoyancy with less pressure reduction even though the tagged and control groups exhibited similar densities. This relation was confirmed by using Boyle's law to simulate buoyancy changes with change in depth. Although fish compensated for the transmitter, changes in depth affected the buoyancy of tagged fish more than that of untagged fish. Reduced buoyancy at depth may affect the behavior and physiology of tagged juvenile salmonids, and researchers should be aware of this potential bias in telemetry data. In addition, there was little difference in PR or the slope of the density - PR regression lines between tagged groups. This was caused by the small difference in excess mass (i.e., weight in water) of the two transmitters. Thus, although two transmitters may not weigh the same, their effects on buoyancy may be similar depending on the excess mass.

Paeoniae alba Radix Promotes Peripheral Nerve Regeneration

PubMed Central

Huang, Kun-Shan; Lin, Jaung-Geng; Lee, Han-Chung; Tsai, Fuu-Jen; Bau, Da-Tian; Huang, Chih-Yang; Yao, Chun-Hsu; Chen, Yueh-Sheng

2011-01-01

The present study provides in vitro and in vivo evaluation of Paeoniae alba Radix (PR) on peripheral nerve regeneration. In the in vitro study, we found the PR caused a marked enhancement of the nerve growth factor-mediated neurite outgrowth from PC12 cells as well as their expression of growth associated protein 43 and synapsin I. In the in vivo study, silicone rubber chambers filled with the PR water extract were used to bridge a 10-mm sciatic nerve defect in rats. At the conclusion of 8 weeks, regenerated nerves in the PR groups, especially at 1.25 mg ml−1 had a higher rate of successful regeneration across the wide gap, relatively larger mean values of total nerve area, myelinated axon count and blood vessel number, and a significantly larger nerve conductive velocity compared to the control group (P  <  .05). These results suggest that the PR extract can be a potential nerve growth-promoting factor, being salutary in aiding the growth of injured peripheral nerve. PMID:19687191

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleurial, J.; Caillat, T.; Borshchevsky, A.

Based on literature data and experimental findings at the Jet Propulsion Laboratory (JPL), semiconductors with the skutterudite structure TPn{sub 3} (where T is a transition metal element such as Co, Rh, Ir, Ni, and Pd, and Pn is a pnicogen element such as P, As, and Sb) possess attractive characteristics and show a good potential for high {ital ZT} values. The high degree of covalency results in high mobility and low electrical resistivity values while a relatively complex 32 atom unit cell results in a reasonably low thermal conductivity. Both {ital n}-type and {ital p}-type electrical conductivity samples have beenmore » obtained. Room temperature Seebeck coefficient values up to 200 {mu}VK{sup {minus}1} for {ital p}-type and up to {minus}600 {mu}VK{sup {minus}1} for {ital n}-type have also been measured on several of these materials. In addition, the large number of isostructural compounds, solid solutions and related phases offer many possibilities for optimization of the transport properties to a specific temperature range of thermoelectric applications. By replacing the transition metal or the pnicogen atom by two of its neighboring elements and ensuring that the number of valence electrons is retained, many ternary phases can be successfully derived from the original CoAs{sub 3} skutterudite structure. Some of these materials were found to have substantially lower thermal conductivities compared to those of the binary compounds. The composition, band gap and doping level can be tailored to achieve maximum performance. An overview of the results obtained to date is provided and our approach to achieving high {ital ZT} materials are discussed in this paper. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less

Possibilities of creating a pure coal-fired power industry based on nanomaterials

NASA Astrophysics Data System (ADS)

Zyryanov, V. V.

2015-08-01

A concept of distributed multigeneration during combustion of homogenized solid fuels with the addition of oxygen-enriched (to 30-50%) air is proposed. To implement this concept, application of medium-temperature δ-Bi2O3/Ag-nanocermet-based membranes is suggested under low pressures and sweeping of oxygen by the cleaned exit gas or the air. The primary product of the multigeneration is microsphere materials. The heat, the AC and the DC electric energy, the cleaned exit gases with a high CO2 content, and volatile elements adsorbed by the filters are the secondary products. To completely clean the exit gases, which is necessary to implement the distributed multigeneration, an array of successive passive plants is proposed. A thermoelectric module based on a BiTeSb-skutterudite nanocomposite is effective in generation of the DC electric energy at microthermoelectric power plants.

Electron doped layered nickelates: Spanning the phase diagram of the cuprates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Botana, Antia S.; Pardo, Victor; Norman, Michael R.

2017-07-01

Pr4Ni3O8 is an overdoped analog of hole-doped layered cuprates. Here we show via ab initio calculations that Ce-doped Pr4Ni3O8 (Pr3CeNi3O8) has the same electronic structure as the antiferromagnetic insulating phase of parent cuprates.We find that substantial Ce doping should be thermodynamically stable and that other 4+ cations would yield a similar antiferromagnetic insulating state, arguing this configuration is robust for layered nickelates of low-enough valence. The analogies with cuprates at different d fillings suggest that intermediate Ce-doping concentrations near 1/8 should be an appropriate place to search for superconductivity in these low-valence Ni oxides.

Status of underrepresented minority and female faculty at medical schools located within Historically Black Colleges and in Puerto Rico

PubMed Central

Mader, Emily M.; Rodríguez, José E.; Campbell, Kendall M.; Smilnak, Timothy; Bazemore, Andrew W.; Petterson, Stephen; Morley, Christopher P.

2016-01-01

Background and objectives To assess the impact of medical school location in Historically Black Colleges and Universities (HBCU) and Puerto Rico (PR) on the proportion of underrepresented minorities in medicine (URMM) and women hired in faculty and leadership positions at academic medical institutions. Method AAMC 2013 faculty roster data for allopathic medical schools were used to compare the racial/ethnic and gender composition of faculty and chair positions at medical schools located within HBCU and PR to that of other medical schools in the United States. Data were compared using independent sample t-tests. Results Women were more highly represented in HBCU faculty (mean HBCU 43.5% vs. non-HBCU 36.5%, p=0.024) and chair (mean HBCU 30.1% vs. non-HBCU 15.6%, p=0.005) positions and in PR chair positions (mean PR 38.23% vs. non-PR 15.38%, p=0.016) compared with other allopathic institutions. HBCU were associated with increased African American representation in faculty (mean HBCU 59.5% vs. non-HBCU 2.6%, p=0.011) and chair (mean HBCU 73.1% vs. non-HBCU 2.2%, p≤0.001) positions. PR designation was associated with increased faculty (mean PR 75.40% vs. non-PR 3.72%, p≤0.001) and chair (mean PR 75.00% vs. non-PR 3.54%, p≤0.001) positions filled by Latinos/Hispanics. Conclusions Women and African Americans are better represented in faculty and leadership positions at HBCU, and women and Latino/Hispanics at PR medical schools, than they are at allopathic peer institutions. PMID:26968254

High performance thermoelectric materials and methods of preparation

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

1997-01-01

Transition metals (T) of Group VIII (Co, Rh and Ir) have been prepared as semiconductor alloys with Sb having the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor alloys and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor alloys having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freeze techniques, liquid-solid phase sintering techniques, low temperature powder sintering and/or hot-pressing. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 8000 cm.sup.2.V.sup.-1.s.sup.-1), good Seebeck coefficients (up to 400 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.), and low thermal conductivities (as low as 15 mW/cmK). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a two fold increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

Optimization of Thermoelectric Components for Automobile Waste Heat Recovery Systems

NASA Astrophysics Data System (ADS)

Kumar, Sumeet; Heister, Stephen D.; Xu, Xianfan; Salvador, James R.

2015-10-01

For a typical spark ignition engine approximately 40% of available thermal energy is lost as hot exhaust gas. To improve fuel economy, researchers are currently evaluating technology which exploits exhaust stream thermal power by use of thermoelectric generators (TEGs) that operate on the basis of the Seebeck effect. A 5% improvement in fuel economy, achieved by use of TEG output power, is a stated objective for light-duty trucks and personal automobiles. System modeling of thermoelectric (TE) components requires solution of coupled thermal and electric fluxes through the n and p-type semiconductor legs, given appropriate thermal boundary conditions at the junctions. Such applications have large thermal gradients along the semiconductor legs, and material properties are highly dependent on spatially varying temperature profiles. In this work, one-dimensional heat flux and temperature variations across thermoelectric legs were solved by using an iterative numerical approach to optimize both TE module and TEG designs. Design traits were investigated by assuming use of skutterudite as a thermoelectric material with potential for automotive applications in which exhaust gas and heat exchanger temperatures typically vary from 100°C to over 600°C. Dependence of leg efficiency, thermal fluxes and electric power generation on leg geometry, fill fractions, electric current, thermal boundary conditions, etc., were studied in detail. Optimum leg geometries were computed for a variety of automotive exhaust conditions.

Selective heterogeneous acid catalyzed esterification of N-terminal sulfyhdryl fatty acids

USDA-ARS?s Scientific Manuscript database

Our interest in thiol fatty acids lies in their antioxidative, free radical scavenging, and metal ion scavenging capabilities as applied to cosmeceutical and skin care formulations. The retail market is filled with products containing the disulfide-containing free fatty acid, lipoic acid. These pr...

Caractéristiques cliniques des jeunes déprimés en pédopsychiatrie

PubMed Central

Breton, Jean-Jacques; Labelle, Réal; Huynh, Christophe; Berthiaume, Claude; St-Georges, Marie; Guilé, Jean-Marc

2012-01-01

Résumé Objectif Décrire le profil clinique de jeunes déprimés selon le groupe d’âge et le sexe. Méthodologie L’étude a été réalisée à l’aide d’une grille d’analyse sur 75 dossiers de jeunes de 6–17 ans enregistrés en pédopsychiatrie en 2002–2003 et présentant un diagnostic de trouble dépressif. Des statistiques descriptives et des tests d’association pour comparer les garçons 6–11 ans, les garçons 12–17 ans et les filles 12–17 ans ont été complétés. Résultats Un jeune sur deux à l’adolescence a doublé une année scolaire. Près de 60% des garçons de 6–11 ans déprimés sont dirigés en pédopsychiatrie pour des difficultés comportementales et 71% des garçons de ce groupe d’âge présentent un trouble dépressif en comorbidité avec un trouble du comportement perturbateur. Les filles et garçons à l’adolescence présentent en plus grande proportion une symptomatologie intériorisée. Les idées suicidaires sont cependant aussi présentes chez les enfants (71%) que chez les adolescents (72%) et les adolescentes (85%). Les problèmes parent-enfant se retrouvent chez la majorité des jeunes, particulièrement chez les adolescentes. Conclusion Il est tout aussi important d’évaluer la dépression et l’idéation suicidaire chez les jeunes garçons avec troubles de comportement que chez les adolescents et les adolescentes et la dimension familiale est importante à considérer dans l’évaluation et le traitement. PMID:22299011

High-Performance Thermoelectric Semiconductors

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre; Caillat, Thierry; Borshchevsky, Alexander

1994-01-01

Figures of merit almost double current state-of-art thermoelectric materials. IrSb3 is semiconductor found to exhibit exceptional thermoelectric properties. CoSb3 and RhSb3 have same skutterudite crystallographic structure as IrSb3, and exhibit exceptional transport properties expected to contribute to high thermoelectric performance. These three compounds form solid solutions. Combination of properties offers potential for development of new high-performance thermoelectric materials for more efficient thermoelectric power generators, coolers, and detectors.

Nonprofits' Expectations in PR Service-Learning Partnerships

ERIC Educational Resources Information Center

Rogers, Cathy; Andrews, Valerie

2016-01-01

Little scholarly evidence exists about the communication needs of nonprofit community partners and what they think constitutes an ideal service-learning (SL) relationship. This study seeks to fill this gap by identifying SL projects and relationships that best serve nonprofit community partners with communication needs. The researchers conducted a…

Identification of a single gene for seed coat impermeability in soybean PI 594619

USDA-ARS?s Scientific Manuscript database

High temperatures during seed fill increase the occurrence of soybeans with impermeable seed coat, which is associated with non-uniform and delayed germination and emergence. This has become an issue in soybean production areas with excessively high-temperature environments. The objectives of the pr...

Modeling of the Thermoelectric Properties of p-Type IrSb(sub 3)

NASA Technical Reports Server (NTRS)

Fleurial, J.

1994-01-01

IrSb(sub 3) is a compound of the skutterudite family of materials now being investigated at JPL. A combination of experimental and theoretical approaches has been recently applied at JPL to evaluate the potential of several thermoelectric materials such as n-type and p-type Si(sub 80) Ge(sub 20) alloys, n-type and p-type Bi(sub 2) Te(sub 3)-based alloys and p-type Ru(sub 2) Ge(sub 3) compound. The use of a comprehensive model for the thermal and electrical transport properties of a given material over its full temperature range of usefulness is a powerful tool for guiding experimental optimization of the composition, temperature and doping level as well as for predicting the maximum ZT value likely to be achieved.

Preparation and physical properties of the GdPr-123 system

NASA Astrophysics Data System (ADS)

Yamani, Z.; Akhavan, M.

1997-06-01

The Gd - Pr solid solution of the `123' crystal structure, 0953-2048/10/6/008/img1 (GdPr-123) with 0953-2048/10/6/008/img2 has been prepared by the standard solid-state reaction technique. Details of sample preparation and results of XRD, SEM, TGA, DT, 0953-2048/10/6/008/img3, and 0953-2048/10/6/008/img4 measurements are reported. For 0953-2048/10/6/008/img5, GdPr-123 is non-superconducting down to 10 K and does not show `metallic' conduction. Samples have a predominantly single-phase orthorhombic structure with Pmmm symmetry and a small percentage (0953-2048/10/6/008/img6) of the Ba sites are occupied by Pr ions in some Pr-rich samples. The lower critical field value measured lies in the range of 10 mT. The nominal valence of the Cu ion in the whole range of x is determined; at the metal - semiconductor boundary 0953-2048/10/6/008/img7, which is smaller by only 0.18 than the value 2.33 of the fully oxygenated 0953-2048/10/6/008/img8 (Gd-123) system. However, the valence of Pr is 3.86+. We suggest that the increasing band filling and localization of states due to the disorder effects together with Pr doping could cause the observed metal - semiconducting transition; qualitatively this is the same as the oxygen depletion case.

Molecular insights of protein contour recognition with ligand pharmacophoric sites through combinatorial library design and MD simulation in validating HTLV-1 PR inhibitors.

PubMed

Selvaraj, Chandrabose; Omer, Ankur; Singh, Poonam; Singh, Sanjeev Kumar

2015-01-01

Retroviruses HIV-1 and HTLV-1 are chiefly considered to be the most dangerous pathogens in Homo sapiens. These two viruses have structurally unique protease (PR) enzymes, which are having common function of its replication mechanism. Though HIV PR drugs failed to inhibit HTLV-1 infections, they emphatically emphasise the need for designing new lead compounds against HTLV-1 PR. Therefore, we tried to understand the binding level interactions through the charge environment present in both ligand and protein active sites. The domino effect illustrates that libraries of purvalanol-A are attuned to fill allosteric binding site of HTLV-1 PR through molecular recognition and shows proper binding of ligand pharmacophoric features in receptor contours. Our screening evaluates seven compounds from purvalanol-A libraries, and these compounds' pharmacophore searches for an appropriate place in the binding site and it places well according to respective receptor contour surfaces. Thus our result provides a platform for the progress of more effective compounds, which are better in free energy calculation, molecular docking, ADME and molecular dynamics studies. Finally, this research provided novel chemical scaffolds for HTLV-1 drug discovery.

Performance Test Results of a Skutterudite-Based Unicouple with a Metallic Coating

NASA Astrophysics Data System (ADS)

Saber, Hamed H.; El-Genk, Mohamed S.; Caillat, Thierry

2005-02-01

A performance test of a Skutterudite-based unicouple (MAY-04) with a metallic coating to suppress the sublimation of antimony from the legs near the hot junction is performed in vacuum (˜ 9 ×10-7 torr) for ˜ 2,000 hours at hot and cold junction temperatures of 892.1 ± 11.9 K and 316.1 ± 5.5 K, respectively. The p-leg is made of CeFe3.5Co0.5Sb12 and the n-leg is made of CoSb3. Presented are the measured voltage-current characteristics, electrical power, open-circuit voltage, and the Seebeck coefficients of the legs as functions of cumulative test time. Also presented is the estimate of the conversion efficiency, ˜ 96 hrs after the start of test. To demonstrate the effectiveness of the metallic coating, the measurements for MAY-04 are compared with those of two uncoated unicouples of the same leg materials (MAR-03 and JUN-03), which had been tested earlier. The cross-sectional areas of the legs in MAY-04 are larger than those in MAR-03 and JUN-03, tested in argon cover gas at ˜ 0.051-0.068 MPa for 450 and 1200 hours, respectively. The open circuit voltage, Voc (204 mV) of MAY-04 at Beginning-Of-Test (BOT) is almost the same as that of MAR-03, but higher than that of JUN-03 (˜180 mV). Although the argon gas effectively decreased antimony loss from legs of MAR-03 and JUN-03, marked degradations in performance occurred with time in these tests. Conversely, the metallic coating in MAY-04 effectively reduced the performance degradation with cumulative test time. The estimated peak efficiency of MAY-04, shortly after BOT (10.65%) is only ˜ 0.37 percentage point lower than the theoretical value, assuming zero side heat losses and zero contact resistance per leg. The peak power of MAY-04 decreased by only ˜12%, from its BOT value of ˜1.6 We to ˜1.4 We after ˜2,000 of cumulative testing.

An effective simplified model of composite compression struts for partially-restrained steel frame with reinforced concrete infill walls

NASA Astrophysics Data System (ADS)

Sun, Guohua; Chuang-Sheng, Walter Yang; Gu, Qiang; DesRoches, Reginald

2018-04-01

To resolve the issue regarding inaccurate prediction of the hysteretic behavior by micro-based numerical analysis for partially-restrained (PR) steel frames with solid reinforced concrete (RC) infill walls, an innovative simplified model of composite compression struts is proposed on the basis of experimental observation on the cracking distribution, load transferring mechanism, and failure modes of RC infill walls filled in PR steel frame. The proposed composite compression struts model for the solid RC infill walls is composed of α inclined struts and main diagonal struts. The α inclined struts are used to reflect the part of the lateral force resisted by shear connectors along the frame-wall interface, while the main diagonal struts are introduced to take into account the rest of the lateral force transferred along the diagonal direction due to the complicated interaction between the steel frame and RC infill walls. This study derives appropriate formulas for the effective widths of the α inclined strut and main diagonal strut, respectively. An example of PR steel frame with RC infill walls simulating simulated by the composite inclined compression struts model is illustrated. The maximum lateral strength and the hysteresis curve shape obtained from the proposed composite strut model are in good agreement with those from the test results, and the backbone curve of a PR steel frame with RC infill walls can be predicted precisely when the inter-story drift is within 1%. This simplified model can also predict the structural stiffness and the equivalent viscous damping ratio well when the inter-story drift ratio exceeds 0.5%.

Temperature and pressure effects on elastic properties of relaxor ferroelectrics and thermoelectrics: A resonant ultrasound spectroscopy study

NASA Astrophysics Data System (ADS)

Tennakoon, Sumudu P.

Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of PMN-PT is observed at temperatures below 400 K. A strong stiffening is observed in the temperature range of 400 K - 673 K, followed by a gradual softening at higher temperatures. With varying pressure, an increased pressure sensitivity of the elastic properties of PMN-PT is observed at the temperatures in the stiffening phase. Elastic behavior at elevated temperatures and pressures were studied for correlations with the ferroelectric domains at temperatures below the Curie temperature (TC), the locally polarized nano-regions, and an existence of pseudo-cubic crystalline at higher temperatures between (TC and TB). Thermoelectric lanthanum tellurides and skutterudites are being investigated by NASA's Jet Propulsion Laboratory for advanced thermoelectric generates (TEGs). Effects of nickel (Ni) doping on elastic properties of lanthanum tellurides at elevated temperatures were investigated in the temperature range of 293 K - 800 K. A linear stiffening was observed with increasing the Ni content in the material. Elastic properties of p-type and n-type bismuth-based skutterudites were investigated in the temperature range of 293 K - 723 K. Elastic properties of rare-earth doped strontium titanate were also investigated in the temperature range of 293 K - 750 K.

The effects of Present Hedonistic Time Perspective and Past Negative Time Perspective on substance use consequences.

PubMed

Chavarria, Jesus; Allan, Nicholas P; Moltisanti, Allison; Taylor, Jeanette

2015-07-01

The overuse of substances can lead to economic, physical, and social consequences. Previous research has demonstrated associations between time perspective and frequency of substance use, but no studies have investigated time perspective's effect on substance use consequences. This study aimed to fill this gap in the literature. Using an MTurk sample (N=531), latent factor models tested the hypothesis that both Present Hedonistic Time Perspective (PrHTP) and Past Negative Time Perspective PaNTP positively predict alcohol and illicit drug use consequences. Bootstrap analyses were then used to test the hypothesis that PrHTP indirectly affected the relationship between PaNTP and alcohol and illicit drug use consequences. PrHTP significantly predicted alcohol and illicit drug use consequences. PaNTP also significantly predicted alcohol and illicit drug use consequences. PrHTP was found to indirectly affect the relationship between PaNTP and substance use consequences for both alcohol and illicit drugs. The findings are consistent with previous research and introduce time perspective as an individual differences risk factor for substance use consequences. The partial and full indirect effects are consistent with the idea that individuals with a PaNTP may develop a PrHTP, placing them at risk for substance use consequences. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Studies of iron impurities in YxPr1-xBa2Cu3O7-delta

NASA Technical Reports Server (NTRS)

Swartzendruber, L. J.; Bennett, L. H.; Ritter, J.; Rubinstein, M.; Harford, M. Z.

1990-01-01

Pr is the only rare earth which, when substituted for Y in YBa2Cu3O7, significantly alters the superconducting transition temperature T(sub c) without changing the crystal structure. For YxPr1-xBa2Cu3O7-delta with delta approx. equal to 0, T(sub c) is reduced rapidly as x is increased, reaching zero for x about 0.5. For x above 0.5 the compound is antiferromagnetic with a Neel temperature that increases with increasing x, rising to above room temperature for x near 1. A similar behavior is observed when the oxygen deficit delta is increased from zero to 1 with x=0. For the case of Pr substitution, the drop in T(sub c) is believed due to magnetic interactions. For the case of varying delta with x=0, the drop can be attributed to a combination of magnetic interactions, band filling, and changes in crystal structure. To study these effects, the Mossbauer effect of 57 Fe atoms substituted for the Cu atoms has been observed as a function of delta, x, and temperature. The observed spectra are all well described by a two quadrupole-split pairs, a central singlet, and a six-line magnetic hyperfine field pattern. For several Pr compositions both delta and temperature were varied, and the results support the hypothesis that a magnetic interaction exists between the Fe in the Cu lattice and the substitutional Pr atoms.

Factors associated with caries: a survey of students from southern Brazil

PubMed Central

Borges, Tássia Silvana; Schwanke, Natalí Lippert; Reuter, Cézane Priscila; Neto, Léo Kraether; Burgos, Miria Suzana

2016-01-01

Abstract Objective: To describe the factors associated with dental caries among students from Santa Cruz do Sul, Rio Grande do Sul, Brazil. Methods: A cross-sectional study was conducted in a random sample of 623 students of both genders, aged 10-17 years old. Tooth decay was performed using the index of the World Health Organization (1997), DMFT (permanent dentition) that expresses the sum of decayed, missing and filled teeth per person. The maternal educational level was rated using criteria of the Brazilian Association of Market Research Companies. The remaining variables were obtained by a structured questionnaire. Poisson regression analysis was used to test the association between variables using robust models and a subsequently adjusted model. Data were expressed as prevalence ratio (PR). Results: Multivariate analysis identified the following factors related to the experience of dental caries: residence in rural municipalities (PR: 1.15; 95%CI: 1.0-1.3), attending a city school (PR: 3.30; 95%CI: 1.1-9.4) or a state school (PR: 3.40; 95%CI: 1.1-9.6); and having an illiterate mother or a mother that only attended up to the 4th year of school (PR: 1.67; 95%CI: 1.1-2.4) or high school (PR: 1.54; 95%CI: 1.1-2.2). Conclusions: The presence of caries in students in southern Brazil was associated with residence in rural areas, mother with little education and attendance to a public school. PMID:27477791

Levers for Thermoelectric Properties in Titania-Based Ceramics

NASA Astrophysics Data System (ADS)

Backhaus-Ricoult, Monika; Rustad, James R.; Vargheese, Deenamma; Dutta, Indrajit; Work, Kim

2012-06-01

While the beneficial impact of nanostructural engineering on thermoelectric performance has been demonstrated for many semiconducting materials (SiGe, skutterudites, PbTe2, etc.), no significant advantages have been reported for oxide nanomaterials. In this study, titania is used as a model material to compare the impact of grain size, doping and substitution, second-phase nanodispersion, and crystallographic defects on the electronic and thermal properties. It is shown that the lattice thermal conductivity can be most efficiently reduced by high densities of crystallographic planar defects in the Magnéli phases, while modification of grain size or introduction of second phases on length scales of 20 nm to 100 nm introduces only minor improvement. For the electronic properties, donor dopants such as niobium provide improvement of the power factor, but are not able to compete with the enhanced carrier concentration that is reached through oxygen vacancy introduction.

Infrared spectra of some sulfides and their analogs of binary composition in the long-wave region

NASA Technical Reports Server (NTRS)

Povarennykh, A. S.; Sidorenko, G. A.; Solntseva, L. S.; Solntsev, B. P.

1981-01-01

The far infrared spectra (500-60/cm) of some simple sulfides and their analogs were studied. In all, 22 minerals with different structure types were investigated, out of which 14 are sulfides (galena, alabandite, pyrrhotite, sphalerite, wurtzite, cinnabar, realgar, orpiment, getchelite antimonite, molybdenite, pyrite, marcasite and heazlewoodite) 6 arsenides (niccolite, domeykite, arsenopyrite, lollingite, rammelsbergite and skutterudite), one telluride (tetradymite) and native arsenic. The main bands of infrared absorption spectra of the minerals are compared with the relative strength of the interatomic bonds and their interpretation is given.

Stability and Correlates of Student Evaluations of Teaching at a Chinese University

ERIC Educational Resources Information Center

Chen, Guo-Hai; Watkins, David

2010-01-01

This paper examines the stability and validity of a student evaluations of teaching (SET) instrument used by the administration at a university in the PR China. The SET scores for two semesters of courses taught by 435 teachers were collected. Total 388 teachers (170 males and 218 females) were also invited to fill out the 60-item NEO Five-Factor…

Diagnostic validity of periapical radiography and CBCT for assessing periapical lesions that persist after endodontic surgery.

PubMed

Kruse, Casper; Spin-Neto, Rubens; Reibel, Jesper; Wenzel, Ann; Kirkevang, Lise-Lotte

2017-10-01

Traditionally, healing after surgical endodontic retreatment (SER); i.e. apicectomy with or without a retrograde filling, is assessed in periapical radiographs (PR). Recently, the use of cone beam CT (CBCT) has increased within endodontics. Generally, CBCT detects more periapical lesions than PR, but basic research on the true nature of these lesions is missing. The objective was to assess the diagnostic validity of PR and CBCT for determining inflammation in SER cases that were re-operated (SER-R) due to unsuccessful healing, using histology of the periapical lesion as reference for inflammation. Records from 149 patients, receiving SER 2004-10, were screened. In total 108 patients (119 teeth) were recalled for clinical follow-up examination, PR and CBCT, of which 74 patients (83 teeth) participated. Three observers assessed PR and CBCT as "successful healing" or "unsuccessful healing" using Rud and Molven's criteria. SER-R was offered to all non-healed teeth with expected favourable prognosis for subsequent functional retention. During SER-R, biopsy was performed and histopathology verified whether or not inflammation was present. All re-operated cases were assessed non-healed in CBCT while 11 of these were assessed successfully healed in PR. Nineteen biopsies were examined. Histopathologic diagnosis revealed 42% (teeth = 8) without periapical inflammation, 16% (teeth = 3) with mild inflammation and 42% (teeth = 8) with moderate to intense inflammation. A correct diagnosis was obtained in 58% with CBCT (true positives) and 63% with PR (true positives+true negatives). Of the re-operated teeth, 42% had no periapical inflammatory lesion, and hence no benefit from SER-R. Not all lesions observed in CBCT represented periapical inflammatory lesions.

Fabrication and Thermoelectric Properties of n-Type CoSb2.85Te0.15 Using Selective Laser Melting.

PubMed

Yan, Yonggao; Ke, Hongquan; Yang, Jihui; Uher, Ctirad; Tang, Xinfeng

2018-04-25

We report a nonequilibrium fabrication method of n-type CoSb 2.85 Te 0.15 skutterudites using selective laser melting (SLM) technology. A powder of CoSb 2.85 Te 0.15 was prepared by self-propagating high-temperature synthesis (SHS) and served as the raw material for the SLM process. The effect of SLM processing parameters such as the laser power and scanning speed on the quality of the forming CoSb 2.85 Te 0.15 thin layers was systematically analyzed, and the optimal processing window for SLM was determined. A brief postannealing at 450 °C for 4 h, following the SLM process, has resulted in a phase-pure CoSb 2.85 Te 0.15 bulk material deposited on a Ti substrate. The Seebeck coefficient of the annealed SLM prepared bulk material is close to that of the sample prepared by the traditional sintering method, and its maximum ZT value reached 0.56 at 823 K. Moreover, a Ti-Co-Sb ternary compound transition layer of about 70 μm in thickness was found at a dense interface between CoSb 2.85 Te 0.15 and the Ti substrate. The contact resistivity was measured as 37.1 μΩcm 2 . The results demonstrate that SLM, coupled with postannealing, can be used for fabrication of incongruently melting skutterudite compounds on heterogeneous substrates. This lays an important foundation for the follow-up research utilizing energy efficient SHS and SLM processes in rapid printing of thermoelectric modules.

The Human Periallocortex: Layer Pattern in Presubiculum, Parasubiculum and Entorhinal Cortex. A Review

PubMed Central

Insausti, Ricardo; Muñoz-López, Mónica; Insausti, Ana M.; Artacho-Pérula, Emilio

2017-01-01

The cortical mantle is not homogeneous, so that three types of cortex can be distinguished: allocortex, periallocortex and isocortex. The main distinction among those three types is based on morphological differences, in particular the number of layers, overall organization, appearance, etc., as well as its connectivity. Additionally, in the phylogenetic scale, this classification is conserved among different mammals. The most primitive and simple cortex is the allocortex, which is characterized by the presence of three layers, with one cellular main layer; it is continued by the periallocortex, which presents six layers, although with enough differences in the layer pattern to separate three different fields: presubiculum (PrS), parasubiculum (PaS), and entorhinal cortex (EC). The closest part to the allocortex (represented by the subiculum) is the PrS, which shows outer (layers I–III) and inner (V–VI) principal layers (lamina principalis externa and lamina principalis interna), both separated by a cell poor band, parallel to the pial surface (layer IV or lamina dissecans). This layer organization is present throughout the anterior-posterior axis. The PaS continues the PrS, but its rostrocaudal extent is shorter than the PrS. The organization of the PaS shows the layer pattern more clearly than in the PrS. Up to six layers are recognizable in the PaS, with layer IV as lamina dissecans between superficial (layers I–III) and deep (V–VI) layers, as in the PrS. The EC presents even more clearly the layer pattern along both mediolateral and rostrocaudal extent. The layer pattern is a thick layer I, layer II in islands, layer III medium pyramids, layer IV as lamina dissecans (not present throughout the EC extent), layer V with dark and big pyramids and a multiform layer VI. The EC borders laterally the proisocortex (incomplete type of isocortex). Variations in the appearance of its layers justify the distinction of subfields in the EC, in particular in human and nonhuman primates. EC layers are not similar to those in the neocortex. The transition between the periallocortical EC and isocortex is not sharp, so that the proisocortex forms an intervening cortex, which fills the gap between the periallocortex and the isocortex. PMID:29046628

The Human Periallocortex: Layer Pattern in Presubiculum, Parasubiculum and Entorhinal Cortex. A Review.

PubMed

Insausti, Ricardo; Muñoz-López, Mónica; Insausti, Ana M; Artacho-Pérula, Emilio

2017-01-01

The cortical mantle is not homogeneous, so that three types of cortex can be distinguished: allocortex, periallocortex and isocortex. The main distinction among those three types is based on morphological differences, in particular the number of layers, overall organization, appearance, etc., as well as its connectivity. Additionally, in the phylogenetic scale, this classification is conserved among different mammals. The most primitive and simple cortex is the allocortex, which is characterized by the presence of three layers, with one cellular main layer; it is continued by the periallocortex, which presents six layers, although with enough differences in the layer pattern to separate three different fields: presubiculum (PrS), parasubiculum (PaS), and entorhinal cortex (EC). The closest part to the allocortex (represented by the subiculum) is the PrS, which shows outer (layers I-III) and inner (V-VI) principal layers ( lamina principalis externa and lamina principalis interna ), both separated by a cell poor band, parallel to the pial surface (layer IV or lamina dissecans ). This layer organization is present throughout the anterior-posterior axis. The PaS continues the PrS, but its rostrocaudal extent is shorter than the PrS. The organization of the PaS shows the layer pattern more clearly than in the PrS. Up to six layers are recognizable in the PaS, with layer IV as lamina dissecans between superficial (layers I-III) and deep (V-VI) layers, as in the PrS. The EC presents even more clearly the layer pattern along both mediolateral and rostrocaudal extent. The layer pattern is a thick layer I, layer II in islands, layer III medium pyramids, layer IV as lamina dissecans (not present throughout the EC extent), layer V with dark and big pyramids and a multiform layer VI. The EC borders laterally the proisocortex (incomplete type of isocortex). Variations in the appearance of its layers justify the distinction of subfields in the EC, in particular in human and nonhuman primates. EC layers are not similar to those in the neocortex. The transition between the periallocortical EC and isocortex is not sharp, so that the proisocortex forms an intervening cortex, which fills the gap between the periallocortex and the isocortex.

Le pronostic statural après une pseudo-puberté précoce par déficit en 11ß hydroxylase chez une fille de 7 ans: à propos d'un cas avec revue de la literature

PubMed Central

Latrech, Hanane; Gaouzi, Ahmed

2015-01-01

L'hyperplasie congénitale des surrénales par déficit en 11ß hydroxylase se voit dans 5 à 10% des cas et est diagnostiquée, habituellement, devant des signes de virilisation d'un nouveau né ou d'un fœtus 46 XX et plus tard devant une HTA avec une hypokaliémie. Le pronostic de taille chez ces patients est très souvent compromis. Nous rapportons le cas d'un déficit en 11ß hydroxylase chez une enfant âgée de 7 ans révélé par une pseudo- puberté précoce traitée par hydrocortisone. La survenue d'une puberté précoce centrale complique encore plus la situation par la mise en jeu du pronostic de taille finale et nécessitant une prise en charge thérapeutique particulière. PMID:26113905

Simulation Experiments of Reacting Two-Phase Flow

DTIC Science & Technology

1987-04-06

to 50 % of the lower gas explosion limit (4 % ofhydrogen in the surrounding air ). Then, this device automatically stops the filling procedure...and the discharge of the rifle into air 68 36. Final chamber pressure versus time (Charge pr’,ssure P, = 12 MPa; closed bomb mode) 70 37. Final...surrounding air , which is entrained turbulently, a combustion process can take place that results in a high intensity flash, called muzzle flash [6

Integrated Heat Switch/Oxide Sorption Compressor

NASA Technical Reports Server (NTRS)

Bard, Steven

1989-01-01

Thermally-driven, nonmechanical compressor uses container filled with compressed praseodymium cerium oxide powder (PrCeOx) to provide high-pressure flow of oxygen gas for driving closed-cycle Joule-Thomson-expansion refrigeration unit. Integrated heat switch/oxide sorption compressor has no moving parts except check valves, which control flow of oxygen gas between compressor and closed-cycle Joule-Thomson refrigeration system. Oxygen expelled from sorbent at high pressure by evacuating heat-switch gap and turning on heater.

Positron Annihilation Measurements of High Temperature Superconductors

NASA Astrophysics Data System (ADS)

Jung, Kang

1995-01-01

The temperature dependence of positron annihilation parameters has been measured for basic YBCO, Dy-doped, and Pr-doped superconducting compounds. The physical properties, such as crystal structure, electrical resistance, and critical temperature, have been studied for all samples. In the basic YBCO and Dy-doped samples, the defect -related lifetime component tau_{2 } was approximately constant from room temperature to above the critical temperature and then showed a step -like decrease in the temperature range 90K { ~} 40K. No significant temperature dependence was found in the short- and long-lifetime components, tau_{1} and tau_{3}. The x-ray diffraction data showed that the crystal structure of these two samples was almost the same. These results indicated that the electronic structure changed below the critical temperature. No transition was observed in the Pr-doped YBCO sample. The advanced computer program "PFPOSFIT" for positron lifetime analysis was modified to run on the UNIX system of the University of Utah. The destruction of superconductivity with Pr doping may be due to mechanisms such as hole filling or hole localization of the charge carriers and may be related to the valence state of the Pr ion. One-parameter analyses like the positron mean lifetime parameter and the Doppler line shape parameter S also have been studied. It was found that a transition in Doppler line shape parameter S was associated with the superconducting transition temperature in basic YBCO, Dy -doped, and 0.5 Pr-doped samples, whereas no transition was observed in the nonsuperconducting Pr-doped sample. The Doppler results indicate that the average electron momentum at the annihilation sites increases as temperature is lowered across the superconducting transition range and that electronic structure change plays an important role in high temperature superconductivity.

Home-based pre-exposure prophylaxis (PrEP) services for gay and bisexual men: An opportunity to address barriers to PrEP uptake and persistence

PubMed Central

Rendina, H. Jonathon; Grov, Christian

2017-01-01

Gay, bisexual, and other men who have sex with men (GBM) are disproportionately affected by the HIV epidemic. Despite the promise of pre-exposure prophylaxis (PrEP) in reducing HIV transmission risk, barriers for uptake and persistence exist. We sought to identify whether GBM in a nationwide cohort who have not yet initiated PrEP (n = 906) would prefer to get PrEP-related care from a primary care provider (PCP) compared to a specialist clinic or provider. We then sought to identify their level of interest and factors associated with preference for using home-based PrEP services (i.e., HB-PrEP), defined to participants as conducting HIV/STI self-testing from home with PrEP prescription mailing after an initial in-person clinic visit. We examined the associations of demographics, sexual HIV transmission risk, concern about frequent medical checkups associated with PrEP, health care access, and PrEP intentions with preferences for healthcare provider type and HB-PrEP. Concern about frequent medical checkups were associated with preferring a PCP for PrEP-related care, but men who perceived a barrier to bringing up the topic of PrEP with a doctor preferred a specialist clinic or provider more than a PCP. HB-PrEP was more appealing for younger men and those engaged in sexual HIV transmission risk, suggesting HB-PrEP could help reach GBM most vulnerable to HIV and in need of PrEP. HB-PrEP expansion has potential to increase PrEP uptake and persistence among GBM, particularly for men with barriers to clinic-based care and higher intentions to initiate PrEP. Clinical guidelines regarding HB-PrEP are needed to expand its use. PMID:29281688

The uranium-bearing nickel-cobalt-native silver deposits in the Black Hawk district, Grant County, New Mexico

USGS Publications Warehouse

Gillerman, Elliot; Whitebread, Donald H.

1953-01-01

The Black Hawk (Bullard Peak) district, Grant County, N. Mex., is 21 miles by road west of Silver City. From 1881 to 1893 more than $1,000,000.00 of high-grade silver ore is reported to have been shipped from the district. Since 1893 there has been no mining in the district except during a short period in 1917 when the Black Hawk mine was rehabilitated. Pre-Cambrian quartz diorite gneiss, which contains inclusions of quartzite, schist, monzonite, and quartz monzonite, is the most widespread rock in the district. The quartz diorite gneiss is intruded by many pre-Cambrian and younger rocks, including diorite granite, diabase, monzonite porphyry and andesite and is overlain by the Upper Cretaceous Beartooth quartzite. The monzonite porphyry, probably of late Cretaceous or early Tertiary age, forms a small stock along the northwestern edge of the district and numerous dikes and irregular masses throughout the district. The ore deposits are in fissure veins that contain silver, cobalt, and uranium. The ore minerals, which include native silver, niccolite, millerite, skutterudite, nickel skutterudite, bismuthinite, pitchblende, and sphalerite, are in a carbonate gangue in narrow, persistent veins, most of which trend northeasterly. Pitchblende has been identified in the Black Hawk and the Alhabra deposits and unidentified radioactive minerals were found at five other localities. The deposits that contain the radioactive minerals constitude a belt 600 to 1,500 feet wide that trends about N. 45° E., and is approximately parallel to the southeastern boundary of the monzonite porphyry stock. All the major ore deposits are in the quartz diorite gneiss in close proximity to the monzonite porphyry. The ore deposits are similar to the deposits at Great Bear Lake, Canada, and Joachimstahl, Czechoslovakia.

Novel rattling of K atoms in aluminium-doped defect pyrochlore tungstate

NASA Astrophysics Data System (ADS)

Shoko, Elvis; Kearley, Gordon J.; Peterson, Vanessa K.; Mutka, Hannu; Koza, Michael M.; Yamaura, Jun-ichi; Hiroi, Zenji; Thorogood, Gordon J.

2014-07-01

Rattling dynamics have been identified as fundamental to superconductivity in defect pyrochlore osmates and aluminium vanadium intermetallics, as well as low thermal conductivity in clathrates and filled skutterudites. Combining inelastic neutron scattering (INS) measurements and ab initio molecular dynamics (MD) simulations, we use a new approach to investigate rattling in the Al-doped defect pyrochlore tungstates: AAl0.33W1.67O6 (A = K, Rb, Cs). We find that although all the alkali metals rattle, the rattling of the K atoms is unique, not only among the tungstates but also among the analogous defect osmates, KOs2O6 and RbOs2O6. Detailed analysis of the MD trajectories reveals that two unique features set the K dynamics apart from the rest, namely, (1) quasi one-dimensional local diffusion within a cage, and (2) vibration at a range of frequencies. The local diffusion is driven by strongly anharmonic local potentials around the K atoms exhibiting a double-well structure in the direction of maximum displacement, which is also the direction of local diffusion. On the other hand, vibration at a range of frequencies is a consequence of the strong anisotropy in the local potentials around the K atoms as revealed by directional magnitude spectra. We present evidence to show that it is the smaller size rather than the smaller mass of the K rattler which leads to the unusual dynamics. Finally, we suggest that the occurrence of local diffusion and vibration at a range of frequencies in the dynamics of a single rattler, as found here for the K atoms, may open new possibilities for phonon engineering in thermoelectric materials.

Design Model for the Heat Transfer in a Short Straight Tube Boiler.

DTIC Science & Technology

1981-06-01

Equilibrium Quality XT - True Quality XTT - Martinelli Parameter Dimensionless Groups Nu - Nusselt Number Pr - Prandtl Number Re - Reynolds Number...fill a cylinder in which a piston was mounted. When the steam was suddenly condensed by a spray of water, a partial vacuum was created, and the piston...BOILER - 1725 SFET YAL OOS _ FIGURE 6: JAMES WATTS WAGON-TYPE BOILER - 1785 25 water-inlet, a condensate return, a steam outlet, a gauge glass for

Feasibility of an eight-week outpatient-based pulmonary rehabilitation program for advanced lung cancer patients undergoing cytotoxic chemotherapy in Korea.

PubMed

Park, Young Sik; Lee, Jinwoo; Keum, Bhumsuk; Oh, Byung-Mo

2018-06-22

The scientific evidence supporting pulmonary rehabilitation (PR) for lung cancer patients undergoing cytotoxic chemotherapy is accumulating; however, the feasibility of outpatient-based PR in these patients has not yet been evaluated in Korea. We conducted an eight-week outpatient-based PR feasibility study in a tertiary referral hospital setting. Patients with advanced lung cancer (non-small cell lung cancer IIIB-IV and small-cell lung cancer extensive disease) scheduled to undergo first-line cytotoxic chemotherapy underwent PR consisting of 60-minute sessions twice a week under the guidance and supervision of a physical therapist, for a total of eight weeks. Feasibility was assessed based on completion of the PR program. In total, 12 patients (median age 68 years) were enrolled; 11 (91.7%) were male with a history of smoking. Among these 12 patients, 9 (75%) completed the eight-week outpatient-based PR program. Three patients could not complete the PR program: two were unwilling and one died from complications of lung cancer. This study showed a 75% completion rate of an eight-week outpatient-based PR program for advanced lung cancer patients undergoing cytotoxic chemotherapy, which supports its feasibility. © 2018 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

Specific Types of Coal Macerals from Orzesze and Ruda Beds from "Pniówek" Coal Mine (Upper Silesian Coal Basin - Poland) as a Manifestation of Thermal Metamorphism

NASA Astrophysics Data System (ADS)

Adamczyk, Zdzisław; Komorek, Joanna; Lewandowska, Małgorzata

2014-03-01

Subject of the research were coal samples from the seams of Orzesze and Ruda beds from "Pniówek" coal mine. All samples represent methabituminous coal B, which present high vitrinite content (V mmf > 60%). Optical character of vitrinite from all analyzed coal samples is biaxial negative and it is characterized by low differentiation of bireflectance. The experiments have shown that the coal rank of investigated samples is generally decreasing with increasing both depth of coal seams and the distance between sampling point and the Carboniferous roof. It may suggests inversion of coalification. Specific types of macerals, typical for thermally metamorphosed coals have been found for all analysed coal samples. It was found, presence of such components like: fluorescing bituminous substance (FBS) filling of cellular spaces in semifusinite, fusinite, and funginite; pseudomorphs after megaspores exhibiting strong bireflectance, and anisotropic semifusinite. Petrographic components with a structure similar to structure of coke and pyrolytic carbon were observed rarely. Presence of colotelinite grains which are visible darker, impregnated with bituminous substance and exhibiting weak fluorescence may be related with influence of temperature on coal. Carbonates occur as filling of cellular spaces in semifusinite, in examined coal samples and there are the effect of thermal alteration of coal. Przedmiotem badań były próbki węgla z pokładów warstw orzeskich i rudzkich KWK Pniówek. Badane próbki reprezentują węgiel średniouwęglony typu B (metabitumiczny), wysokowitrynitowy. Stwierdzono, że witrynit z badanych próbek ma dwuosiowy ujemny charakter optyczny i wykazuje małe zróżnicowanie w wartościach dwójodbicia. Przeprowadzone badania wykazały, że stopień uwęglenia badanych próbek generalnie maleje wraz ze wzrostem głębokości występowania pokładów węgla oraz ze wzrostem odległości miejsca opróbowania od stropu karbonu co może wskazywać na inwersję uwęglenia. We wszystkich analizowanych próbkach węgla stwierdzono występowanie specyficznych odmian macerałów typowych dla węgli zmetamorfizowanych termicznie. W próbkach stwierdzono obecność takich składników jak: fluoryzująca substancja bitumiczna (FBS) wypełniająca przestrzenie komórkowe w semifuzynicie, fuzynicie i funginicie; pseudomorfozy po makrosporach wykazujące silne dwójodbicie oraz anizotropowy semifuzynit. Rzadziej obserwowano składniki petrograficzne o strukturze wykazującej podobieństwo do struktury koksu i węgiel pirolityczny. Z oddziaływaniem temperatury na badany węgiel można wiązać także obecność w analizowanych próbkach wyraźnie ciemniejszych, przesyconych substancją bitumiczną, wykazujących słabą fluorescencję ziaren kolotelinitu. Przejawem przemian termicznych obserwowanych w badanych próbkach węgla może być także obecność węglanów najczęściej wypełniających przestrzenie komórkowe w semifuzynicie.

Scoping a field experiment: error diagnostics of TRMM precipitation radar estimates in complex terrain as a basis for IPHEx2014

NASA Astrophysics Data System (ADS)

Duan, Y.; Wilson, A. M.; Barros, A. P.

2014-10-01

A diagnostic analysis of the space-time structure of error in Quantitative Precipitation Estimates (QPE) from the Precipitation Radar (PR) on the Tropical Rainfall Measurement Mission (TRMM) satellite is presented here in preparation for the Integrated Precipitation and Hydrology Experiment (IPHEx) in 2014. IPHEx is the first NASA ground-validation field campaign after the launch of the Global Precipitation Measurement (GPM) satellite. In anticipation of GPM, a science-grade high-density raingauge network was deployed at mid to high elevations in the Southern Appalachian Mountains, USA since 2007. This network allows for direct comparison between ground-based measurements from raingauges and satellite-based QPE (specifically, PR 2A25 V7 using 5 years of data 2008-2013). Case studies were conducted to characterize the vertical profiles of reflectivity and rain rate retrievals associated with large discrepancies with respect to ground measurements. The spatial and temporal distribution of detection errors (false alarm, FA, and missed detection, MD) and magnitude errors (underestimation, UND, and overestimation, OVR) for stratiform and convective precipitation are examined in detail toward elucidating the physical basis of retrieval error. The diagnostic error analysis reveals that detection errors are linked to persistent stratiform light rainfall in the Southern Appalachians, which explains the high occurrence of FAs throughout the year, as well as the diurnal MD maximum at midday in the cold season (fall and winter), and especially in the inner region. Although UND dominates the magnitude error budget, underestimation of heavy rainfall conditions accounts for less than 20% of the total consistent with regional hydrometeorology. The 2A25 V7 product underestimates low level orographic enhancement of rainfall associated with fog, cap clouds and cloud to cloud feeder-seeder interactions over ridges, and overestimates light rainfall in the valleys by large amounts, though this behavior is strongly conditioned by the coarse spatial resolution (5 km) of the terrain topography mask used to remove ground clutter effects. Precipitation associated with small-scale systems (< 25 km2) and isolated deep convection tends to be underestimated, which we attribute to non-uniform beam-filling effects due to spatial averaging of reflectivity at the PR resolution. Mixed precipitation events (i.e., cold fronts and snow showers) fall into OVR or FA categories, but these are also the types of events for which observations from standard ground-based raingauge networks are more likely subject to measurement uncertainty, that is raingauge underestimation errors due to under-catch and precipitation phase. Overall, the space-time structure of the errors shows strong links among precipitation, envelope orography, landform (ridge-valley contrasts), and local hydrometeorological regime that is strongly modulated by the diurnal cycle, pointing to three major error causes that are inter-related: (1) representation of concurrent vertically and horizontally varying microphysics; (2) non uniform beam filling (NUBF) effects and ambiguity in the detection of bright band position; and (3) spatial resolution and ground clutter correction.

Scoping a field experiment: error diagnostics of TRMM precipitation radar estimates in complex terrain as a basis for IPHEx2014

NASA Astrophysics Data System (ADS)

Duan, Y.; Wilson, A. M.; Barros, A. P.

2015-03-01

A diagnostic analysis of the space-time structure of error in quantitative precipitation estimates (QPEs) from the precipitation radar (PR) on the Tropical Rainfall Measurement Mission (TRMM) satellite is presented here in preparation for the Integrated Precipitation and Hydrology Experiment (IPHEx) in 2014. IPHEx is the first NASA ground-validation field campaign after the launch of the Global Precipitation Measurement (GPM) satellite. In anticipation of GPM, a science-grade high-density raingauge network was deployed at mid to high elevations in the southern Appalachian Mountains, USA, since 2007. This network allows for direct comparison between ground-based measurements from raingauges and satellite-based QPE (specifically, PR 2A25 Version 7 using 5 years of data 2008-2013). Case studies were conducted to characterize the vertical profiles of reflectivity and rain rate retrievals associated with large discrepancies with respect to ground measurements. The spatial and temporal distribution of detection errors (false alarm, FA; missed detection, MD) and magnitude errors (underestimation, UND; overestimation, OVR) for stratiform and convective precipitation are examined in detail toward elucidating the physical basis of retrieval error. The diagnostic error analysis reveals that detection errors are linked to persistent stratiform light rainfall in the southern Appalachians, which explains the high occurrence of FAs throughout the year, as well as the diurnal MD maximum at midday in the cold season (fall and winter) and especially in the inner region. Although UND dominates the error budget, underestimation of heavy rainfall conditions accounts for less than 20% of the total, consistent with regional hydrometeorology. The 2A25 V7 product underestimates low-level orographic enhancement of rainfall associated with fog, cap clouds and cloud to cloud feeder-seeder interactions over ridges, and overestimates light rainfall in the valleys by large amounts, though this behavior is strongly conditioned by the coarse spatial resolution (5 km) of the topography mask used to remove ground-clutter effects. Precipitation associated with small-scale systems (< 25 km2) and isolated deep convection tends to be underestimated, which we attribute to non-uniform beam-filling effects due to spatial averaging of reflectivity at the PR resolution. Mixed precipitation events (i.e., cold fronts and snow showers) fall into OVR or FA categories, but these are also the types of events for which observations from standard ground-based raingauge networks are more likely subject to measurement uncertainty, that is raingauge underestimation errors due to undercatch and precipitation phase. Overall, the space-time structure of the errors shows strong links among precipitation, envelope orography, landform (ridge-valley contrasts), and a local hydrometeorological regime that is strongly modulated by the diurnal cycle, pointing to three major error causes that are inter-related: (1) representation of concurrent vertically and horizontally varying microphysics; (2) non-uniform beam filling (NUBF) effects and ambiguity in the detection of bright band position; and (3) spatial resolution and ground-clutter correction.

Crystal structure of an FIV/HIV chimeric protease complexed with the broad-based inhibitor, TL-3.

PubMed

Heaslet, Holly; Lin, Ying-Chuan; Tam, Karen; Torbett, Bruce E; Elder, John H; Stout, C David

2007-01-09

We have obtained the 1.7 A crystal structure of FIV protease (PR) in which 12 critical residues around the active site have been substituted with the structurally equivalent residues of HIV PR (12X FIV PR). The chimeric PR was crystallized in complex with the broad-based inhibitor TL-3, which inhibits wild type FIV and HIV PRs, as well as 12X FIV PR and several drug-resistant HIV mutants 1234. Biochemical analyses have demonstrated that TL-3 inhibits these PRs in the order HIV PR > 12X FIV PR > FIV PR, with Ki values of 1.5 nM, 10 nM, and 41 nM, respectively 234. Comparison of the crystal structures of the TL-3 complexes of 12X FIV and wild-typeFIV PR revealed theformation of additinal van der Waals interactions between the enzyme inhibitor in the mutant PR. The 12X FIV PR retained the hydrogen bonding interactions between residues in the flap regions and active site involving the enzyme and the TL-3 inhibitor in comparison to both FIV PR and HIV PR. However, the flap regions of the 12X FIV PR more closely resemble those of HIV PR, having gained several stabilizing intra-flap interactions not present in wild type FIV PR. These findings offer a structural explanation for the observed inhibitor/substrate binding properties of the chimeric PR.

Gas-liquid countercurrent integration process for continuous biodiesel production using a microporous solid base KF/CaO as catalyst.

PubMed

Hu, Shengyang; Wen, Libai; Wang, Yun; Zheng, Xinsheng; Han, Heyou

2012-11-01

A continuous-flow integration process was developed for biodiesel production using rapeseed oil as feedstock, based on the countercurrent contact reaction between gas and liquid, separation of glycerol on-line and cyclic utilization of methanol. Orthogonal experimental design and response surface methodology were adopted to optimize technological parameters. A second-order polynomial model for the biodiesel yield was established and validated experimentally. The high determination coefficient (R(2)=98.98%) and the low probability value (Pr<0.0001) proved that the model matched the experimental data, and had a high predictive ability. The optimal technological parameters were: 81.5°C reaction temperature, 51.7cm fill height of catalyst KF/CaO and 105.98kPa system pressure. Under these conditions, the average yield of triplicate experiments was 93.7%, indicating the continuous-flow process has good potential in the manufacture of biodiesel. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mg2BIV: Narrow Bandgap Thermoelectric Semiconductors

NASA Astrophysics Data System (ADS)

Kim, Il-Ho

2018-05-01

Thermoelectric materials can convert thermal energy directly into electric energy and vice versa. The electricity generation from waste heat via thermoelectric devices can be considered as a new energy source. For instance, automotive exhaust gas and all industrial processes generate an enormous amount of waste heat that can be converted to electricity by using thermoelectric devices. Magnesium compound Mg2BIV (BIV = Si, Ge or Sn) has a favorable combination of physical and chemical properties and can be a good base for the development of new efficient thermoelectrics. Because they possess similar properties to those of group BIV elemental semiconductors, they have been recognized as good candidates for thermoelectric applications. Mg2Si, Mg2Ge and Mg2Sn with an antifluorite structure are narrow bandgap semiconductors with indirect band gaps of 0.77 eV, 0.74 eV, and 0.35 eV, respectively. Mg2BIV has been recognized as a promising material for thermoelectric energy conversion at temperatures ranging from 500 K to 800 K. Compared to other thermoelectric materials operating in the similar temperature range, such as PbTe and filled skutterudites, the important aspects of Mg2BIV are non-toxic and earth-abundant elements. Based on classical thermoelectric theory, the material factor β ( m* / m e)3/2μκ L -1 can be utilized as the criterion for thermoelectric material selection, where m* is the density-of-states effective mass, me is the mass of an electron, μ is the carrier mobility, and κL is the lattice thermal conductivity. The β for magnesium silicides is 14, which is very high compared to 0.8 for iron silicides, 1.4 for manganese silicides, and 2.6 for silicon-germanium alloys. In this paper, basic phenomena of thermoelectricity and transport parameters for thermoelectric materials were briefly introduced, and thermoelectric properties of Mg2BIV synthesized by using a solid-state reaction were reviewed. In addition, various Mg2BIV compounds were discussed: intrinsic Mg2Si, doped Mg2Si:Dm (D = Al, In, Bi, Sb, Te or Se), and solid solutions of intrinsic/doped Mg2Si1 - x Sn x :D m and Mg2Si1 - x Ge x :D m .

Three-dimensional fusion of spaceborne and ground radar reflectivity data using a neural network-based approach

NASA Astrophysics Data System (ADS)

Kou, Leilei; Wang, Zhuihui; Xu, Fen

2018-03-01

The spaceborne precipitation radar onboard the Tropical Rainfall Measuring Mission satellite (TRMM PR) can provide good measurement of the vertical structure of reflectivity, while ground radar (GR) has a relatively high horizontal resolution and greater sensitivity. Fusion of TRMM PR and GR reflectivity data may maximize the advantages from both instruments. In this paper, TRMM PR and GR reflectivity data are fused using a neural network (NN)-based approach. The main steps included are: quality control of TRMM PR and GR reflectivity data; spatiotemporal matchup; GR calibration bias correction; conversion of TRMM PR data from Ku to S band; fusion of TRMM PR and GR reflectivity data with an NN method; interpolation of reflectivity data that are below PR's sensitivity; blind areas compensation with a distance weighting-based merging approach; combination of three types of data: data with the NN method, data below PR's sensitivity and data within compensated blind areas. During the NN fusion step, the TRMM PR data are taken as targets of the training NNs, and gridded GR data after horizontal downsampling at different heights are used as the input. The trained NNs are then used to obtain 3D high-resolution reflectivity from the original GR gridded data. After 3D fusion of the TRMM PR and GR reflectivity data, a more complete and finer-scale 3D radar reflectivity dataset incorporating characteristics from both the TRMM PR and GR observations can be obtained. The fused reflectivity data are evaluated based on a convective precipitation event through comparison with the high resolution TRMM PR and GR data with an interpolation algorithm.

Adherence to Preexposure Prophylaxis: Current, Emerging, and Anticipated Bases of Evidence

PubMed Central

Amico, K. Rivet; Stirratt, Michael J.

2014-01-01

Despite considerable discussion and debate about adherence to preexposure prophylaxis (PrEP) for human immunodeficiency virus (HIV), scant data are available that characterize patterns of adherence to open-label PrEP. The current evidence base is instead dominated by research on adherence to placebo-controlled investigational drug by way of drug detection in active-arm participants of large randomized controlled trials (RCTs). Important differences between the context of blinded RCTs and open-label use suggest caution when generalizing from study product adherence to real-world PrEP use. Evidence specific to open-label PrEP adherence is presently sparse but will expand rapidly over the next few years as roll-out, demonstration projects, and more rigorous research collect and present findings. The current evidence bases established cannot yet predict uptake, adherence, or persistence with open-label effective PrEP. Emerging evidence suggests that some cohorts could execute better adherence in open-label use vs placebo-controlled research. Uptake of PrEP is presently slow in the United States; whether this changes as grassroots and community efforts increase awareness of PrEP as an effective HIV prevention option remains to be determined. As recommended by multiple guidelines for PrEP use, all current demonstration projects offer PrEP education and/or counseling. PrEP support approaches generally fall into community-based, technology, monitoring, and integrated sexual health promotion approaches. Developing and implementing research that moves beyond simple correlates of either study product use or open-label PrEP adherence toward more comprehensive models of sociobehavioral and socioecological adherence determinants would greatly accelerate progress. Intervention research is needed to identify effective models of support for open-label PrEP adherence. PMID:24926036

Archaeological Investigations at 30 Historic Sites, Chief Joseph Dam Project, Washington.

DTIC Science & Technology

1984-01-01

145 Figure 7-10. Light green distemper medicine bottle from saloon cellar fill, Condon Ferry tradIng post (45-DO-202H) ....... ... 146 Figure 7-11...became more popular after 1900. The few medicine bottles represented In our collection include a nearly full bottle of distemper medicine and a tonic for...2 . I-’. o a .4 .= .’* -- 146 PR w 0 3 CM. Figure 7-10. Light green distemper medicine bottie from saloon cellar f Ill, Condon Ferry trading post

Uncovering the defence responses of Eucalyptus to pests and pathogens in the genomics age.

PubMed

Naidoo, Sanushka; Külheim, Carsten; Zwart, Lizahn; Mangwanda, Ronishree; Oates, Caryn N; Visser, Erik A; Wilken, Febé E; Mamni, Thandekile B; Myburg, Alexander A

2014-09-01

Long-lived tree species are subject to attack by various pests and pathogens during their lifetime. This problem is exacerbated by climate change, which may increase the host range for pathogens and extend the period of infestation by pests. Plant defences may involve preformed barriers or induced resistance mechanisms based on recognition of the invader, complex signalling cascades, hormone signalling, activation of transcription factors and production of pathogenesis-related (PR) proteins with direct antimicrobial or anti-insect activity. Trees have evolved some unique defence mechanisms compared with well-studied model plants, which are mostly herbaceous annuals. The genome sequence of Eucalyptus grandis W. Hill ex Maiden has recently become available and provides a resource to extend our understanding of defence in large woody perennials. This review synthesizes existing knowledge of defence mechanisms in model plants and tree species and features mechanisms that may be important for defence in Eucalyptus, such as anatomical variants and the role of chemicals and proteins. Based on the E. grandis genome sequence, we have identified putative PR proteins based on sequence identity to the previously described plant PR proteins. Putative orthologues for PR-1, PR-2, PR-4, PR-5, PR-6, PR-7, PR-8, PR-9, PR-10, PR-12, PR-14, PR-15 and PR-17 have been identified and compared with their orthologues in Populus trichocarpa Torr. & A. Gray ex Hook and Arabidopsis thaliana (L.) Heynh. The survey of PR genes in Eucalyptus provides a first step in identifying defence gene targets that may be employed for protection of the species in future. Genomic resources available for Eucalyptus are discussed and approaches for improving resistance in these hardwood trees, earmarked as a bioenergy source in future, are considered. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Crystal structure of an FIV/HIV chimeric protease complexed with the broad-based inhibitor, TL-3

PubMed Central

Heaslet, Holly; Lin, Ying-Chuan; Tam, Karen; Torbett, Bruce E; Elder, John H; Stout, C David

2007-01-01

We have obtained the 1.7 Å crystal structure of FIV protease (PR) in which 12 critical residues around the active site have been substituted with the structurally equivalent residues of HIV PR (12X FIV PR). The chimeric PR was crystallized in complex with the broad-based inhibitor TL-3, which inhibits wild type FIV and HIV PRs, as well as 12X FIV PR and several drug-resistant HIV mutants [1-4]. Biochemical analyses have demonstrated that TL-3 inhibits these PRs in the order HIV PR > 12X FIV PR > FIV PR, with Ki values of 1.5 nM, 10 nM, and 41 nM, respectively [2-4]. Comparison of the crystal structures of the TL-3 complexes of 12X FIV and wild-typeFIV PR revealed theformation of additinal van der Waals interactions between the enzyme inhibitor in the mutant PR. The 12X FIV PR retained the hydrogen bonding interactions between residues in the flap regions and active site involving the enzyme and the TL-3 inhibitor in comparison to both FIV PR and HIV PR. However, the flap regions of the 12X FIV PR more closely resemble those of HIV PR, having gained several stabilizing intra-flap interactions not present in wild type FIV PR. These findings offer a structural explanation for the observed inhibitor/substrate binding properties of the chimeric PR. PMID:17212810

Falls among the elderly: risk factors in a population-based study.

PubMed

Rodrigues, Iara Guimarães; Fraga, Gustavo Pereira; Barros, Marilisa Berti de Azevedo

2014-01-01

The aim of the present study was to identify factors associated with the occurrence of falls among elderly adults in a population-based study (ISACamp 2008). A population-based cross-sectional study was carried out with two-stage cluster sampling. The sample was composed of 1,520 elderly adults living in the urban area of the city of Campinas, São Paulo, Brazil. The occurrence of falls was analyzed based on reports of the main accident occurred in the previous 12 months. Data on socioeconomic/demographic factors and adverse health conditions were tested for possible associations with the outcome. Prevalence ratios (PR) were estimated and adjusted for gender and age using the Poisson multiple regression analysis. Falls were more frequent, after adjustment for gender and age, among female elderly participants (PR = 2.39; 95% confidence interval (95% CI) 1.47 - 3.87), elderly adults (80 years old and older) (PR = 2.50; 95% CI 1.61 - 3.88), widowed (PR = 1.74; 95% CI 1.04 - 2.89) and among elderly adults who had rheumatism/arthritis/arthrosis (PR = 1.58; 95% CI 1.00 - 2.48), osteoporosis (PR = 1.71; 95% CI 1.18 - 2.49), asthma/bronchitis/emphysema (PR = 1,73; 95% CI 1.09 - 2.74), headache (PR = 1.59; 95% CI 1.07 - 2.38), mental common disorder (PR = 1.72; 95% CI 1.12 - 2.64), dizziness (PR = 2.82; 95% CI 1.98 - 4.02), insomnia (PR = 1.75; 95% CI 1.16 - 2.65), use of multiple medications (five or more) (PR = 2.50; 95% CI 1.12 - 5.56) and use of cane/walker (PR = 2.16; 95% CI 1.19 - 3,93). The present study shows segments of the elderly population who are more prone to falls through the identification of factors associated with this outcome. The findings can contribute to the planning of public health policies and programs addressed to the prevention of falls.

Long-term evaluation of home-based pulmonary rehabilitation in patients with COPD.

PubMed

Grosbois, Jean Marie; Gicquello, Alice; Langlois, Carole; Le Rouzic, Olivier; Bart, Frédéric; Wallaert, Benoit; Chenivesse, Cécile

2015-01-01

Personalized, global pulmonary rehabilitation (PR) management of patients with COPD is effective, regardless of the place in which this rehabilitation is provided. The objective of this retrospective observational study was to study the long-term outcome of exercise capacity and quality of life during management of patients with COPD treated by home-based PR. Home-based PR was administered to 211 patients with COPD (mean age, 62.3±11.1 years; mean forced expiratory volume in 1 second, 41.5%±17.7%). Home-based PR was chosen because of the distance of the patient's home from the PR center and the patient's preference. Each patient was individually managed by a team member once a week for 8 weeks with unsupervised continuation of physical exercises on the other days of the week according to an individual action plan. Exercise conditioning, therapeutic patient education, and self-management were included in the PR program. The home assessment comprised evaluation of the patient's exercise capacity by a 6-minute stepper test, Timed Up and Go test, ten times sit-to-stand test, Hospital Anxiety and Depression score, and quality of life (Visual Simplified Respiratory Questionnaire, VQ11, Maugeri Respiratory Failure 28). No incidents or accidents were observed during the course of home-based PR. The 6-minute stepper test was significantly improved after completion of the program, at 6 months and 12 months, whereas the Timed Up and Go and ten times sit-to-stand test were improved after PR and at 6 months but not at 12 months. Hospital Anxiety and Depression and quality of life scores improved after PR, and this improvement persisted at 6 months and 12 months. Home-based PR for unselected patients with COPD is effective in the short term, and this effectiveness is maintained in the medium term (6 months) and long term (12 months). Home-based PR is an alternative to outpatient management provided all activities, such as exercise conditioning, therapeutic education, and self-management are performed.

Long-term evaluation of home-based pulmonary rehabilitation in patients with COPD

PubMed Central

Grosbois, Jean Marie; Gicquello, Alice; Langlois, Carole; Le Rouzic, Olivier; Bart, Frédéric; Wallaert, Benoit; Chenivesse, Cécile

2015-01-01

Introduction Personalized, global pulmonary rehabilitation (PR) management of patients with COPD is effective, regardless of the place in which this rehabilitation is provided. The objective of this retrospective observational study was to study the long-term outcome of exercise capacity and quality of life during management of patients with COPD treated by home-based PR. Methods Home-based PR was administered to 211 patients with COPD (mean age, 62.3±11.1 years; mean forced expiratory volume in 1 second, 41.5%±17.7%). Home-based PR was chosen because of the distance of the patient’s home from the PR center and the patient’s preference. Each patient was individually managed by a team member once a week for 8 weeks with unsupervised continuation of physical exercises on the other days of the week according to an individual action plan. Exercise conditioning, therapeutic patient education, and self-management were included in the PR program. The home assessment comprised evaluation of the patient’s exercise capacity by a 6-minute stepper test, Timed Up and Go test, ten times sit-to-stand test, Hospital Anxiety and Depression score, and quality of life (Visual Simplified Respiratory Questionnaire, VQ11, Maugeri Respiratory Failure 28). Results No incidents or accidents were observed during the course of home-based PR. The 6-minute stepper test was significantly improved after completion of the program, at 6 months and 12 months, whereas the Timed Up and Go and ten times sit-to-stand test were improved after PR and at 6 months but not at 12 months. Hospital Anxiety and Depression and quality of life scores improved after PR, and this improvement persisted at 6 months and 12 months. Conclusion Home-based PR for unselected patients with COPD is effective in the short term, and this effectiveness is maintained in the medium term (6 months) and long term (12 months). Home-based PR is an alternative to outpatient management provided all activities, such as exercise conditioning, therapeutic education, and self-management are performed. PMID:26445534

From nonpeptide toward noncarbon protease inhibitors: Metallacarboranes as specific and potent inhibitors of HIV protease

PubMed Central

Cígler, Petr; Kožíšek, Milan; Řezáčová, Pavlína; Brynda, Jíří; Otwinowski, Zbyszek; Pokorná, Jana; Plešek, Jaromír; Grüner, Bohumír; Dolečková-Marešová, Lucie; Máša, Martin; Sedláček, Juraj; Bodem, Jochen; Kräusslich, Hans-Georg; Král, Vladimír; Konvalinka, Jan

2005-01-01

HIV protease (PR) represents a prime target for rational drug design, and protease inhibitors (PI) are powerful antiviral drugs. Most of the current PIs are pseudopeptide compounds with limited bioavailability and stability, and their use is compromised by high costs, side effects, and development of resistant strains. In our search for novel PI structures, we have identified a group of inorganic compounds, icosahedral metallacarboranes, as candidates for a novel class of nonpeptidic PIs. Here, we report the potent, specific, and selective competitive inhibition of HIV PR by substituted metallacarboranes. The most active compound, sodium hydrogen butylimino bis-8,8-[5-(3-oxa-pentoxy)-3-cobalt bis(1,2-dicarbollide)]di-ate, exhibited a Ki value of 2.2 nM and a submicromolar EC50 in antiviral tests, showed no toxicity in tissue culture, weakly inhibited human cathepsin D and pepsin, and was inactive against trypsin, papain, and amylase. The structure of the parent cobalt bis(1,2-dicarbollide) in complex with HIV PR was determined at 2.15 Å resolution by protein crystallography and represents the first carborane-protein complex structure determined. It shows the following mode of PR inhibition: two molecules of the parent compound bind to the hydrophobic pockets in the flap-proximal region of the S3 and S3′ subsites of PR. We suggest, therefore, that these compounds block flap closure in addition to filling the corresponding binding pockets as conventional PIs. This type of binding and inhibition, chemical and biological stability, low toxicity, and the possibility to introduce various modifications make boron clusters attractive pharmacophores for potent and specific enzyme inhibition. PMID:16227435

[Comparison of long-term dental treatment effects of children treated under general anesthesia and passive restraint].

PubMed

Zhou, F; Xia, B; Zhang, S; Ma, W L; Xiao, Y M; Ge, L H

2017-02-09

Objective: To compare the long-term dental treatment effects, oral health habits and oral-health-related qualities of life of children treated under general anesthesia (GA) and passive restraint (PR), respectively. Methods: Twenty seven 2 to 4-year-old children treated under GA and thirty four children treated under PR were recruited in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. Up to 2 years after the treatment, a follow up assessment was conducted. The data of general information, dental plaque level and the unplanned treatments were recorded and analyzed. The questionnaire of oral health habits and early childhood oral health impact scale (ECOHIS) for each child was also completed and analyzed. The survival rate and median survival time of the deciduous teeth were calculated. Multivariate analysis was performed by using Cox proportional hazard model. Results: Twenty-five children under GA and 32 under PR were finally included, with a total of 1 098 deciduous teeth. The postoperative dental plaque indicesin both GA and PR groups had significantly improved than that of before the treatments ( P= 0.019, P< 0.001). The oral health habits had also improved, and the improvement in PR group was more obvious than that in GA group. Totally 128 teeth (27.0%) appeared unplanned treatments in GA group and 232 teeth (37.2%) in PR group during the follow-ups. The new caries and recurrent caries in PR group were significantly more than that in GA group ( P< 0.001, P= 0.012). No significant differences were found between the two groups in restoration failure, secondary caries and endodontic diseases ( P= 0.129, P= 0.822, P= 0.642). However, the time of occurrence of endodontic disease and secondary caries in GA group were significantly longer than that in PR group ( P< 0.01, P< 0.001). The median survival time of teeth in GA group was 1 018 days comparing to 944 days in PR group. The difference was statistically significant ( P< 0.05). The survival rate was associated with such factors as decayed-missing-filled tooth (dmft), anterior or posterior teeth, feeding frequency, brushing habits and behavior management techniques. Conclusions: The long-term dental treatment effects of children treated under GA was significantly better than that of PR group. Continuous reinforcement of proper dietary and oral hygiene habits might help in maintaining the long-term treatment effect.

Vegetable and fruit consumption and the risk of hormone receptor-defined breast cancer in the EPIC cohort.

PubMed

Emaus, Marleen J; Peeters, Petra H M; Bakker, Marije F; Overvad, Kim; Tjønneland, Anne; Olsen, Anja; Romieu, Isabelle; Ferrari, Pietro; Dossus, Laure; Boutron-Ruault, Marie Christine; Baglietto, Laura; Fortner, Renée T; Kaaks, Rudolf; Boeing, Heiner; Trichopoulou, Antonia; Lagiou, Pagona; Trichopoulos, Dimitrios; Masala, Giovanna; Pala, Valeria; Panico, Salvatore; Tumino, Rosario; Polidoro, Silvia; Skeie, Guri; Lund, Eiliv; Weiderpass, Elisabete; Quirós, J Ramón; Travier, Noémie; Sánchez, María-José; Chirlaque, Maria-Dolores; Ardanaz, Eva; Dorronsoro, Miren; Winkvist, Anna; Wennberg, Maria; Bueno-de-Mesquita, H Bas; Khaw, Kay-Tee; Travis, Ruth C; Key, Timothy J; Aune, Dagfinn; Gunter, Marc; Riboli, Elio; van Gils, Carla H

2016-01-01

The recent literature indicates that a high vegetable intake and not a high fruit intake could be associated with decreased steroid hormone receptor-negative breast cancer risk. This study aimed to investigate the association between vegetable and fruit intake and steroid hormone receptor-defined breast cancer risk. A total of 335,054 female participants in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort were included in this study (mean ± SD age: 50.8 ± 9.8 y). Vegetable and fruit intake was measured by country-specific questionnaires filled out at recruitment between 1992 and 2000 with the use of standardized procedures. Cox proportional hazards models were stratified by age at recruitment and study center and were adjusted for breast cancer risk factors. After a median follow-up of 11.5 y (IQR: 10.1-12.3 y), 10,197 incident invasive breast cancers were diagnosed [3479 estrogen and progesterone receptor positive (ER+PR+); 1021 ER and PR negative (ER-PR-)]. Compared with the lowest quintile, the highest quintile of vegetable intake was associated with a lower risk of overall breast cancer (HRquintile 5-quintile 1: 0.87; 95% CI: 0.80, 0.94). Although the inverse association was most apparent for ER-PR- breast cancer (ER-PR-: HRquintile 5-quintile 1: 0.74; 95% CI: 0.57, 0.96; P-trend = 0.03; ER+PR+: HRquintile 5-quintile 1: 0.91; 95% CI: 0.79, 1.05; P-trend = 0.14), the test for heterogeneity by hormone receptor status was not significant (P-heterogeneity = 0.09). Fruit intake was not significantly associated with total and hormone receptor-defined breast cancer risk. This study supports evidence that a high vegetable intake is associated with lower (mainly hormone receptor-negative) breast cancer risk. © 2016 American Society for Nutrition.

The Vaginal Microbiome and its Potential to Impact Efficacy of HIV Pre-exposure Prophylaxis for Women.

PubMed

Velloza, Jennifer; Heffron, Renee

2017-10-01

This review describes existing evidence addressing the potential modulation of pre-exposure prophylaxis (PrEP) products, specifically 1% tenofovir (TFV) gel and oral tenofovir-based PrEP, by vaginal dysbiosis and discusses future considerations for delivering novel, long-acting PrEP products to women at high risk for vaginal dysbiosis and HIV. We describe results from analyses investigating the modification of PrEP efficacy by vaginal dysbiosis and studies of biological mechanisms that could render PrEP ineffective in the presence of specific microbiota. A secondary analysis from the CAPRISA-004 cohort demonstrated that there is no effect of the 1% TFV gel in the presence of non-Lactobacillus dominant microbiota. Another recent analysis comparing oral tenofovir-based PrEP efficacy among women with and without bacterial vaginosis in the Partners PrEP Study found that oral PrEP efficacy is not modified by bacterial vaginosis. Gardnerella vaginalis, commonly present in women with vaginal dysbiosis, can rapidly metabolize TFV particularly when it is locally applied and thereby prevent TFV integration into cells. Given that vaginal dysbiosis appears to modulate efficacy for 1% TFV gel but not for oral tenofovir-based PrEP, vaginal dysbiosis is potentially less consequential to HIV protection from TFV in the context of systemic drug delivery and high product adherence. Vaginal dysbiosis may undermine the efficacy of 1% TFV gel to protect women from HIV but not the efficacy of oral PrEP. Ongoing development of novel ring, injectable, and film-based PrEP products should investigate whether vaginal dysbiosis can reduce efficacy of these products, even in the presence of high adherence.

Transitioning to HIV Pre-Exposure Prophylaxis (PrEP) from Non-Occupational Post-Exposure Prophylaxis (nPEP) in a Comprehensive HIV Prevention Clinic: A Prospective Cohort Study.

PubMed

Siemieniuk, Reed A C; Sivachandran, Nirojini; Murphy, Pauline; Sharp, Andrea; Walach, Christine; Placido, Tania; Bogoch, Isaac I

2015-08-01

The uptake of pre-exposure prophylaxis (PrEP) for HIV prevention remains low. We hypothesized that a high proportion of patients presenting for HIV non-occupational post-exposure prophylaxis (nPEP) would be candidates for PrEP based on current CDC guidelines. Outcomes from a comprehensive HIV Prevention Clinic are described. We evaluated all patients who attended the HIV Prevention Clinic for nPEP between January 1, 2013 and September 30, 2014. Each patient was evaluated for PrEP candidacy based on current CDC-guidelines and subjectively based on physician opinion. Patients were then evaluated for initiation of PrEP if they met guideline suggestions. Demographic, social, and behavioral factors were then analyzed with logistic regression for associations with PrEP candidacy and initiation. 99 individuals who attended the nPEP clinic were evaluated for PrEP. The average age was 32 years (range, 18-62), 83 (84%) were male, of whom 46 (55%) men who had have sex with men (MSM). 31 (31%) met CDC guidelines for PrEP initiation, which had very good agreement with physician recommendation (kappa=0.88, 0.78-0.98). Factors associated with PrEP candidacy included sexual exposure to HIV, prior nPEP use, and lack of drug insurance (p<0.05 for all comparisons). Combining nPEP and PrEP services in a dedicated clinic can lead to identification of PrEP candidates and may facilitate PrEP uptake. Strategies to ensure equitable access of PrEP should be explored such that those without drug coverage may also benefit from this effective HIV prevention modality.

The severity of dental caries in adults aged 35 to 44 years residing in the metropolitan area of a large city in Brazil: a cross-sectional study.

PubMed

Costa, Simone M; Vasconcelos, Mara; Haddad, João Paulo A; Abreu, Mauro Henrique N G

2012-07-31

In recent decades, studies in the field of public health have increasingly focused on social determinants that affect the health-illness process. The epidemiological perspective considers oral health to be a reflection of socioeconomic and environmental aspects, and it is particularly influenced by the social context. The aim of the present study was to assess the association between the severity of dental caries among adults aged 35 to 44 years and characteristics on the different levels at which the determinants of caries operate (individual, social structure and social context). A home-based, cross-sectional field study was carried out involving a sample of 1,150 adults (35 to 44 years of age) residing in metropolitan Belo Horizonte, Brazil. The DMFT (decayed, missing, filled tooth) index (≥14) was used to determine the severity of dental caries. Bivariate and multivariate analyses were carried out using the Poisson regression model with the level of significance set at 5% (p < 0.05) and 95% confidence intervals. The majority of the participants (68.5%) had high caries severity. The rate of high-severity caries in the group between 40 and 44 years of age was 1.15-fold (CI: 1.04-1.26) greater than that among those aged 35 to 39 years. A greater prevalence of high caries severity was found among those who frequently visited the dentist (PR = 1.18; CI: 1.07-1.30), those with a lower income (PR = 1.11; CI: 1.01-1.23), those who reported that their neighborhood did not come together in the previous year to petition political leaders for benefits (PR = 1.16; CI: 1.05-1.28) and those who are unable to make decisions (without empowerment) (PR = 1.12; CI: 1.01-1.24). The present study revealed high dental caries severity in adults, which was associated with individual characteristics, health-related behavior and social structure and contextual variables. These findings underscore the importance of considering social determinants involved in the health-illness process when carrying out epidemiological studies on dental caries.

Age and sex as moderators of the placebo response – an evaluation of systematic reviews and meta-analyses across medicine.

PubMed

Weimer, Katja; Colloca, Luana; Enck, Paul

2015-01-01

Predictors of the placebo response (PR) in randomized controlled trials (RCT) have been searched for ever since RCT have become the standard for testing novel therapies and age and gender are routinely documented data in all trials irrespective of the drug tested, its indication, and the primary and secondary end points chosen. To evaluate whether age and gender have been found to be reliable predictors of the PR across medical subspecialties, we extracted 75 systematic reviews, meta-analyses, and meta-regressions performed in major medical areas (neurology, psychiatry, internal medicine) known for high PR rates. The literature database used contains approximately 2,500 papers on various aspects of the genuine PR. These ‘meta-analyses’ were screened for statistical predictors of the PR across multiple RCT, including age and gender, but also other patient-based and design-based predictors of higher PR rates. Retrieved papers were sorted for areas and disease categories. Only 15 of the 75 analyses noted an effect of younger age to be associated with higher PR, and this was predominantly in psychiatric conditions but not in depression, and internal medicine but not in gastroenterology. Female gender was associated with higher PR in only 3 analyses. Among the patient-based predictors, the most frequently noted factor was lower symptom severity at baseline, and among the design- based factors, it was a randomization ratio that selected more patients to drugs than to placebo, more frequent study visits, and more recent trials that were associated with higher PR rates. While younger age may contribute to the PR in some conditions, sex does not. There is currently no evidence that the PR is different in the elderly. PR are, however, markedly influenced by the symptom severity at baseline, and by the likelihood of receiving active treatment in placebo- controlled trials. © 2014 S. Karger AG, Basel.

The Effects of Rainfall Inhomogeneity on Climate Variability of Rainfall Estimated from Passive Microwave Sensors

NASA Technical Reports Server (NTRS)

Kummerow, Christian; Poyner, Philip; Berg, Wesley; Thomas-Stahle, Jody

2007-01-01

Passive microwave rainfall estimates that exploit the emission signal of raindrops in the atmosphere are sensitive to the inhomogeneity of rainfall within the satellite field of view (FOV). In particular, the concave nature of the brightness temperature (T(sub b)) versus rainfall relations at frequencies capable of detecting the blackbody emission of raindrops cause retrieval algorithms to systematically underestimate precipitation unless the rainfall is homogeneous within a radiometer FOV, or the inhomogeneity is accounted for explicitly. This problem has a long history in the passive microwave community and has been termed the beam-filling error. While not a true error, correcting for it requires a priori knowledge about the actual distribution of the rainfall within the satellite FOV, or at least a statistical representation of this inhomogeneity. This study first examines the magnitude of this beam-filling correction when slant-path radiative transfer calculations are used to account for the oblique incidence of current radiometers. Because of the horizontal averaging that occurs away from the nadir direction, the beam-filling error is found to be only a fraction of what has been reported previously in the literature based upon plane-parallel calculations. For a FOV representative of the 19-GHz radiometer channel (18 km X 28 km) aboard the Tropical Rainfall Measuring Mission (TRMM), the mean beam-filling correction computed in this study for tropical atmospheres is 1.26 instead of 1.52 computed from plane-parallel techniques. The slant-path solution is also less sensitive to finescale rainfall inhomogeneity and is, thus, able to make use of 4-km radar data from the TRMM Precipitation Radar (PR) in order to map regional and seasonal distributions of observed rainfall inhomogeneity in the Tropics. The data are examined to assess the expected errors introduced into climate rainfall records by unresolved changes in rainfall inhomogeneity. Results show that global mean monthly errors introduced by not explicitly accounting for rainfall inhomogeneity do not exceed 0.5% if the beam-filling error is allowed to be a function of rainfall rate and freezing level and does not exceed 2% if a universal beam-filling correction is applied that depends only upon the freezing level. Monthly regional errors can be significantly larger. Over the Indian Ocean, errors as large as 8% were found if the beam-filling correction is allowed to vary with rainfall rate and freezing level while errors of 15% were found if a universal correction is used.

Validation of TRMM Precipitation Radar Through Comparison of its Multi-Year Measurements to Ground-Based Radar

NASA Technical Reports Server (NTRS)

Liao, Liang; Meneghini, Robert

2010-01-01

A procedure to accurately resample spaceborne and ground-based radar data is described, and then applied to the measurements taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and the ground-based Weather Surveillance Radar-1988 Doppler (WSR-88D or WSR) for the validation of the PR measurements and estimates. Through comparisons with the well-calibrated, non-attenuated WSR at Melbourne, Florida for the period 1998-2007, the calibration of the Precipitation Radar (PR) aboard the TRMM satellite is checked using measurements near the storm top. Analysis of the results indicates that the PR, after taking into account differences in radar reflectivity factors between the PR and WSR, has a small positive bias of 0.8 dB relative to the WSR, implying a soundness of the PR calibration in view of the uncertainties involved in the comparisons. Comparisons between the PR and WSR reflectivities are also made near the surface for evaluation of the attenuation-correction procedures used in the PR algorithms. It is found that the PR attenuation is accurately corrected in stratiform rain but is underestimated in convective rain, particularly in heavy rain. Tests of the PR estimates of rainfall rate are conducted through comparisons in the overlap area between the TRMM overpass and WSR scan. Analyses of the data are made both on a conditional basis, in which the instantaneous rain rates are compared only at those pixels where both the PR and WSR detect rain, and an unconditional basis, in which the area-averaged rain rates are estimated independently for the PR and WSR. Results of the conditional rain comparisons show that the PR-derived rain is about 9% greater and 19% less than the WSR estimates for stratiform and convective storms, respectively. Overall, the PR tends to underestimate the conditional mean rain rate by 8% for all rain categories, a finding that conforms to the results of the area-averaged rain (unconditional) comparisons.

When the science fails and the ethics works: 'Fail-safe' ethics in the FEM-PrEP study.

PubMed

Kingori, Patricia

2015-12-01

This paper will explore the concept of 'fail safe' ethics in the FEM PrEP trial, and the practice of research and ethics on the ground. FEM-PrEP examined the efficacy of PrEP in African women after promising outcomes in research conducted with MSM. This was a hugely optimistic time and FEM-PrEP was mobilised using rights-based ethical arguments that women should have access to PrEP. This paper will present data collected during an ethnographic study of frontline research workers involved in FEM-PrEP. During our discussions, 'fail-safe' ethics emerged as concept that encapsulated their confidence that their ethics could not fail. However, in 2011, FEM-PrEP was halted and deemed a failure. The women involved in the study were held responsible because contrary to researcher's expectations they were not taking the oral PrEP being researched. This examination of FEM-PrEP will show that ethical arguments are increasingly deployed to mobilise, maintain and in some cases stop trials in ways which, at times, are superseded or co-opted by other interests. While promoting the interests of women, rights-based approaches are argued to indirectly justify the continuation of individualised, biomedical interventions which have been problematic in other women-centred trials. In this examination of FEM-PrEP, the rights-based approach obscured: ethical concerns beyond access to PrEP; the complexities of power relationships between donor and host countries; the operations of the HIV industry in research-saturated areas and the cumulative effect of unfilled expectations in HIV research and how this has shaped ideas of research and ethics.

Digital Solutions for Informed Decision Making: An Academic-Community Partnership for the Development of a Prostate Cancer Decision Aid for African American Men.

PubMed

Owens, Otis L; Friedman, Daniela B; Brandt, Heather M; Bernhardt, Jay M; Hébert, James R

2016-05-01

African American (AA) men are significantly more likely to die of prostate cancer (PrCA) than other racial groups, and there is a critical need to identify strategies for providing information about PrCA screening and the importance of informed decision making (IDM). To assess whether a computer-based IDM intervention for PrCA screening would be appropriate for AA men, this formative evaluation study examined their (1) PrCA risk and screening knowledge; (2) decision-making processes for PrCA screening; (3) usage of, attitudes toward, and access to interactive communication technologies (ICTs); and (4) perceptions regarding a future, novel, computer-based PrCA education intervention. A purposive convenience sample of 39 AA men aged 37 to 66 years in the Southeastern United States was recruited through faith-based organizations to participate in one of six 90-minute focus groups and complete a 45-item descriptive survey. Participants were generally knowledgeable about PrCA. However, few engaged in IDM with their doctor and few were informed about the associated risks and uncertainties of PrCA screening. Most participants used ICTs on a daily basis for various purposes including health information seeking. Most participants were open to a novel, computer-based intervention if the system was easy to use and its animated avatars were culturally appropriate. Because study participants had low exposure to IDM for PrCA, but frequently used ICTs, IDM interventions using ICTs (e.g., computers) hold promise for AA men and should be explored for feasibility and effectiveness. These interventions should aim to increase PrCA screening knowledge and stress the importance of participating in IDM with doctors. © The Author(s) 2015.

Release of Full-Length PrPC from Cultured Neurons Following Neurotoxic Challenge

PubMed Central

Wang, Kevin K. W.; Zoltewicz, J. Susie; Chiu, Allen; Zhang, Zhiqun; Rubenstein, Richard

2012-01-01

The susceptibility of the normal cellular prion protein isoform, cellular prion protein (PrPC), to proteolytic digestion has been well documented. In addition, a link between PrPC and the cytosolic protease, calpain, has been reported although the specifics of the interaction remain unclear. We performed in vitro and in cell-based studies to examine this relationship. We observed that human recombinant PrP (HrPrP) was readily cleaved by calpain-1 and -2, and we have identified and defined the targeted cleavage sites. In contrast, HrPrP was resistant to caspase-3 digestion. Unexpectedly, when brain lysates from PrPC-expressing mice were treated with calpain, no appreciable loss of the intact PrPC, nor the appearance of PrPC breakdown products (BDPs) were observed, even though alpha II-spectrin was converted to its signature calpain-induced BDPs. In addition, when rat cerebrocortical neuronal cultures (RtCNC) were subjected to the two neurotoxins at subacute levels, maitotoxin (MTX) and N-methyl-d-aspartate (NMDA), PrPC-BDPs were also not detectable. However, a novel finding from these cell-based studies is that apparently full-length, mature PrPC is released into culture media from RtCNC challenged with subacute doses of MTX and NMDA. Calpain inhibitor SNJ-1945 and caspase inhibitor IDN-6556 did not attenuate the release of PrPC. Similarly, the lysosomal protease inhibitor, NH4Cl, and the proteasome inhibitor, lactacystin, did not significantly alter the integrity of PrPC or its release from the RtCNC. In conclusion, rat neuronal PrPC is not a significant target for proteolytic modifications during MTX and NMDA neurotoxic challenges. However, the robust neurotoxin-mediated release of full-length PrPC into the cell culture media suggests an unidentified neuroprotective mechanism for PrPC. PMID:23093947

Self-perceived oral health influences tooth brushing in preschool children.

PubMed

Agostini, Bernardo Antonio; Machry, Rômulo Vaz; Teixeira, Carlos Roberto da Silva; Piovesan, Chaiana; Oliveira, Marta Dutra Machado; Bresolin, Carmela Rampazzo; Ardenghi, Thiago Machado

2014-01-01

This study assessed the influence of socioeconomic and clinical factors, as well as parent's perception of child's oral health on the toothbrushing frequency of 0-5-year-old children. The study was carried out in Santa Maria, RS, Brazil, during the National Children's Vaccination Day, and 478 children aged 0-5 years were included. Data were collected by clinical examinations and a structured questionnaire, conducted by 15 calibrated examiners and 30 supports. A questionnaire was filled out by the parents with information about several socioeconomic indicators, perception of child's oral health and frequency of tooth brushing. The main outcome was collected by the question: "How many times a day do you brush your child's teeth?". Multivariable Poisson regression model taking into account the cluster sample was performed to assess the association between the predictors and outcome. Children whose parents related worse perception of child's oral health showed less tooth brushing frequency (PR 1.23; 1.06 - 1.43). Young children brush their teeth less than the older ones (PR 0.90; 0.84 - 0.96); and lack of visit to a dentist was predictor for less tooth brushing frequency (PR 1.29; 1.05 - 1.59). Parent's perception of child oral health influence children's healthy behaviors, supporting the evidence that psychosocial factors are strong predictors of children's oral health.

Fracture resistance of immature teeth filled with BioAggregate, mineral trioxide aggregate and calcium hydroxide.

PubMed

Tuna, Elif Bahar; Dinçol, Muzaffer Emir; Gençay, Koray; Aktören, Oya

2011-06-01

Abstract -  Background: The aim of this in vitro study was to assess the long-term fracture resistance of human immature permanent teeth filled with BioAggregate (BA), mineral trioxide aggregate (MTA) and calcium hydroxide (CH).  The study consisted of single rooted premolar teeth with immature root formation extracted for orthodontic reasons. A total of 28 immature premolars with average root length of 10.7 mm and apical diameter of 3 mm were included in the study. The pulps were extirpated and the canals were prepared using an apical approach. The teeth were randomly assigned to four groups: Group I: DiaRoot(®) BA (DiaDent, Burnaby, BC, Canada), Group II: Angelus MTA (MTA-A; Angelus, Londrina, Brazil), Group III: ProRoot(®) MTA (MTA-PR; Dentsply, Tulsa, OK, USA), Group IV: CH (Sultan Chemists Inc., Englewood, NJ, USA). The teeth were placed in saline solution at 4°C for 1 year. The root of each tooth was then embedded in an acrylic resin block. All specimens were loaded at a crosshead speed of 1 mm min(-1) in an Instron testing machine and the peak loads up to fracture were recorded. Data were analysed statistically by Kruskal-Wallis and Mann-Whitney U-tests.  Mean (±SD) failure loads (MPa) were: 37.69 ± 14.43 for BA group, 32.94 ± 8.15 for MTA-A group, 28.74 ± 9.49 for MTA-PR group and 23.18 ± 8.48 for CH group. The BA group exhibited the highest fracture resistance and the CH group showed the lowest resistance to fracture. Significant differences (P < 0.05) in fracture resistance were found between the DiaRoot-BA and CH groups, and also between the MTA-A and CH groups.  Within the limitations of this study, data suggest that DiaRoot-BA-filled immature teeth demonstrate higher fracture resistance than other groups at 1 year. Considering the long-term risk of cervical root fracture associated with immature teeth, the use of DiaRoot-BA as a root canal filling material appears to be the most advantageous of the materials tested. © 2011 John Wiley & Sons A/S.

Mg-enriched erythrite from Bou Azzer, Anti-Atlas Mountains, Morocco: geochemical and spectroscopic characteristics

NASA Astrophysics Data System (ADS)

Dumańska-Słowik, Magdalena; Pieczka, Adam; Natkaniec-Nowak, Lucyna; Kunecki, Piotr; Gaweł, Adam; Heflik, Wiesław; Smoliński, Wojciech; Kozub-Budzyń, Gabriela

2018-06-01

Supergene Mg-enriched erythrite, with an average composition (Co2.25Mg0.58Ni0.14Fe0.04Mn0.02 Zn0.02) (As1.97P<0.01O8)·8H2O, accompanied by skutterudite, roselite and alloclasite, was identified in a pneumo-hydrothermal quartz-feldspar-carbonate matrix within the ophiolite sequence of Bou Azzer in Morocco. The unit cell parameters of monoclinic Mg-enriched erythrite [space group C2/ m, a = 10.252(2) Å, b = 13.427(3) Å, c = 4.757(3) Å, ß = 105.12(1)°] make the mineral comparable with erythrite from other localities. The composition of the sample represents the solid solution between erythrite, hörnesite and annabergite, that is, the nearest to the endmember erythrite. However, Mg-enriched erythrite forming the crystal exhibits variable compositions, especially in Mg and Co contents, with Mg increasing from 0.32 up to 1.39 apfu, and Co decreasing from 2.53 to 1.50 apfu, which manifests in the fine compositional oscillatory zoning. It is the highest content of Mg in erythrite structure reported so far. The most intensive Raman active ν3 and ν1 bands, recorded for the crystal's zones with maximum Mg contents, occur at 865 and 800 cm- 1 and are shifted towards higher wavenumbers, where normally hörnesite Raman bands appear. The characteristic oscillatory zoning texture results from varying contents of main and trace elements mobilized from the host ores (Co arsenides, mainly skutterudite) and rock-forming minerals (among others, dolomite) by the solutions in the oxidation zone of the ore deposits. The heating of the Mg-enriched erythrite up to 1000 °C leads to the crystallization of the water-free (Co,Mg)3(AsO4)2 phase.

The chemistry of prions: small molecules, protein conformers and mass spectrometry

USDA-ARS?s Scientific Manuscript database

Background/Introduction. Prions propagate by converting a normal cellular isoform (PrPC) into the prion isoform (PrPSc) in a template-driven process. The lysines in PrPC are highly conserved and strongly influence prion propagation, based on studies using natural polymorphisms of PrPC and transg...

Interactive web-based pulmonary rehabilitation programme: a randomised controlled feasibility trial

PubMed Central

Chaplin, Emma; Hewitt, Stacey; Apps, Lindsay; Bankart, John; Pulikottil-Jacob, Ruth; Boyce, Sally; Morgan, Mike; Williams, Johanna; Singh, Sally

2017-01-01

Objectives The aim of this study was to determine if an interactive web-based pulmonary rehabilitation (PR) programme is a feasible alternative to conventional PR. Design Randomised controlled feasibility trial. Setting Participants with a diagnosis of chronic obstructive pulmonary disease were recruited from PR assessments, primary care and community rehabilitation programmes. Patients randomised to conventional rehabilitation started the programme according to the standard care at their referred site on the next available date. Participants 103 patients were recruited to the study and randomised: 52 to conventional rehabilitation (mean (±SD) age 66 (±8) years, Medical Research Council (MRC) 3 (IQR2–4)); 51 to the web arm (mean (±SD) age 66 (±10) years, MRC 3 (IQR2–4)). Participants had to be willing to participate in either arm of the trial, have internet access and be web literate. Interventions Patients randomised to the web-based programme worked through the website, exercising and recording their progress as well as reading educational material. Conventional PR consisted of twice weekly, 2 hourly sessions (an hour for exercise training and an hour for education). Outcome measures Recruitment rates, eligibility, patient preference and dropout and completion rates for both programmes were collected. Standard outcomes for a PR assessment including measures of exercise capacity and quality of life questionnaires were also evaluated. Results A statistically significant improvement (p≤0.01) was observed within each group in the endurance shuttle walk test (WEB: mean change 189±211.1; PR classes: mean change 184.5±247.4 s) and Chronic Respiratory disease Questionnaire-Dyspnoea (CRQ-D; WEB: mean change 0.7±1.2; PR classes: mean change 0.8±1.0). However, there were no significant differences between the groups in any outcome. Dropout rates were higher in the web-based programme (57% vs 23%). Conclusions An interactive web-based PR programme is feasible and acceptable when compared with conventional PR. Future trials maybe around choice-based PR programmes for select patients enabling stratification of patient care. Trial registration number ISRCTN03142263; Results. PMID:28363923

Interactive web-based pulmonary rehabilitation programme: a randomised controlled feasibility trial.

PubMed

Chaplin, Emma; Hewitt, Stacey; Apps, Lindsay; Bankart, John; Pulikottil-Jacob, Ruth; Boyce, Sally; Morgan, Mike; Williams, Johanna; Singh, Sally

2017-03-31

The aim of this study was to determine if an interactive web-based pulmonary rehabilitation (PR) programme is a feasible alternative to conventional PR. Randomised controlled feasibility trial. Participants with a diagnosis of chronic obstructive pulmonary disease were recruited from PR assessments, primary care and community rehabilitation programmes. Patients randomised to conventional rehabilitation started the programme according to the standard care at their referred site on the next available date. 103 patients were recruited to the study and randomised: 52 to conventional rehabilitation (mean (±SD) age 66 (±8) years, Medical Research Council (MRC) 3 (IQR2-4)); 51 to the web arm (mean (±SD) age 66 (±10) years, MRC 3 (IQR2-4)). Participants had to be willing to participate in either arm of the trial, have internet access and be web literate. Patients randomised to the web-based programme worked through the website, exercising and recording their progress as well as reading educational material. Conventional PR consisted of twice weekly, 2 hourly sessions (an hour for exercise training and an hour for education). Recruitment rates, eligibility, patient preference and dropout and completion rates for both programmes were collected. Standard outcomes for a PR assessment including measures of exercise capacity and quality of life questionnaires were also evaluated. A statistically significant improvement (p≤0.01) was observed within each group in the endurance shuttle walk test (WEB: mean change 189±211.1; PR classes: mean change 184.5±247.4 s) and Chronic Respiratory disease Questionnaire-Dyspnoea (CRQ-D; WEB: mean change 0.7±1.2; PR classes: mean change 0.8±1.0). However, there were no significant differences between the groups in any outcome. Dropout rates were higher in the web-based programme (57% vs 23%). An interactive web-based PR programme is feasible and acceptable when compared with conventional PR. Future trials maybe around choice-based PR programmes for select patients enabling stratification of patient care. ISRCTN03142263; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

From PACS to Web-based ePR system with image distribution for enterprise-level filmless healthcare delivery.

PubMed

Huang, H K

2011-07-01

The concept of PACS (picture archiving and communication system) was initiated in 1982 during the SPIE medical imaging conference in New Port Beach, CA. Since then PACS has been matured to become an everyday clinical tool for image archiving, communication, display, and review. This paper follows the continuous development of PACS technology including Web-based PACS, PACS and ePR (electronic patient record), enterprise PACS to ePR with image distribution (ID). The concept of large-scale Web-based enterprise PACS and ePR with image distribution is presented along with its implementation, clinical deployment, and operation. The Hong Kong Hospital Authority's (HKHA) integration of its home-grown clinical management system (CMS) with PACS and ePR with image distribution is used as a case study. The current concept and design criteria of the HKHA enterprise integration of the CMS, PACS, and ePR-ID for filmless healthcare delivery are discussed, followed by its work-in-progress and current status.

Safety of oral tenofovir disoproxil fumarate-based HIV pre-exposure prophylaxis use in lactating HIV-uninfected women.

PubMed

Mugwanya, Kenneth K; John-Stewart, Grace; Baeten, Jared

2017-07-01

In settings where HIV is prevalent in heterosexual populations, pregnancy and postpartum breastfeeding periods can be associated with substantial HIV acquisition risk. Pre-exposure prophylaxis (PrEP) with daily oral tenofovir disoproxil fumarate (TDF)/emtricitabine is an attractive HIV prevention option for women who are lactating but data are limited on its safety during the lactation period. Areas covered: We provide a concise synthesis and summary of current evidence on the safety of TDF-based PrEP during breastfeeding. We conducted a review, searching Pubmed database and major PrEP conferences for primary studies with TDF-based PrEP exposure during postpartum breastfeeding. Expert opinion: TDF-based oral PrEP is an effective female-controlled HIV prevention option. There is evidence supporting the safety of TDF use for infant outcomes during breastfeeding in antiretroviral treatment regimens for HIV and hepatitis B virus, and more limited, but consistently safe, data from use of TDF as PrEP. The potential for risk is arguably outweighed for at-risk individuals by HIV prevention benefits, including indirect protection to the infant as a result of preventing HIV in the breastfeeding mother. As PrEP delivery is scaled up in heterosexual populations in high HIV prevalence settings and for at-risk persons in other settings, implementation science studies can provide a framework to increase the accrual of safety, acceptability, and use data related to PrEP during lactation.

Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification

PubMed Central

Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

2016-01-01

Prions are formed of misfolded assemblies (PrPSc) of the variably N-glycosylated cellular prion protein (PrPC). In infected species, prions replicate by seeding the conversion and polymerization of host PrPC. Distinct prion strains can be recognized, exhibiting defined PrPSc biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrPSc assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrPC glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrPC species of interest as substrate. Applying the technique to PrPC glycosylation mutants expressing cells revealed that neither PrPC nor PrPSc glycoform stoichiometry was instrumental to PrPSc formation and strainness perpetuation. Our study supports the view that strain properties, including PrPSc glycotype are enciphered within PrPSc structural backbone, not in the attached glycans. PMID:27384922

Discovery of Novel Anti-prion Compounds Using In Silico and In Vitro Approaches

PubMed Central

Hyeon, Jae Wook; Choi, Jiwon; Kim, Su Yeon; Govindaraj, Rajiv Gandhi; Jam Hwang, Kyu; Lee, Yeong Seon; An, Seong Soo A.; Lee, Myung Koo; Joung, Jong Young; No, Kyoung Tai; Lee, Jeongmin

2015-01-01

Prion diseases are associated with the conformational conversion of the physiological form of cellular prion protein (PrPC) to the pathogenic form, PrPSc. Compounds that inhibit this process by blocking conversion to the PrPSc could provide useful anti-prion therapies. However, no suitable drugs have been identified to date. To identify novel anti-prion compounds, we developed a combined structure- and ligand-based virtual screening system in silico. Virtual screening of a 700,000-compound database, followed by cluster analysis, identified 37 compounds with strong interactions with essential hotspot PrP residues identified in a previous study of PrPC interaction with a known anti-prion compound (GN8). These compounds were tested in vitro using a multimer detection system, cell-based assays, and surface plasmon resonance. Some compounds effectively reduced PrPSc levels and one of these compounds also showed a high binding affinity for PrPC. These results provide a promising starting point for the development of anti-prion compounds. PMID:26449325

Functional Knowledge of Pre-Exposure Prophylaxis for HIV Prevention Among Participants in a Web-Based Survey of Sexually Active Gay, Bisexual, and Other Men Who Have Sex With Men: Cross-Sectional Study

PubMed Central

2018-01-01

Background Awareness of pre-exposure prophylaxis (PrEP) for HIV prevention is increasing, but little is known about the functional knowledge of PrEP and its impact on willingness to use PrEP. Objective The objective of this study was to assess the functional knowledge of PrEP among a sample of gay, bisexual, and other men who have sex with men (MSM) participating in a Web-based survey of sexually active MSM. Methods Men at least 18 years old, residing in the United States, and reporting sex with a man in the previous 6 months were recruited through social networking websites. PrEP functional knowledge included the following 4 questions (1) efficacy of consistent PrEP use, (2) inconsistent PrEP use and effectiveness, (3) PrEP and condom use, and (4) effectiveness at reducing sexually transmitted infections (STIs). Ordinal logistic regression was used to identify respondent characteristics associated with PrEP functional knowledge. In a subsample of participants responding to HIV prevention questions, we compared willingness to use PrEP by response to PrEP functional knowledge using logistic regression analysis adjusted for age, race and ethnicity, and education level. Results Among 573 respondents, PrEP knowledge was high regarding adherence (488/573, 85.2%), condom use (532/573, 92.8%), and STIs (480/573, 83.8%), but only 252/573 (44.0%) identified the correct efficacy. Lower functional PrEP knowledge was associated with minority race/ethnicity (P=.005), lower education (P=.01), and not having an HIV test in the past year (P=.02). Higher PrEP knowledge was associated with willingness to use PrEP (P=.009). Younger age was not associated with higher PrEP functional knowledge or willingness to use PrEP. Conclusions PrEP knowledge was generally high in our study, including condom use and consistent use but may be lacking in higher risk MSM. The majority of respondents did not correctly identify PrEP efficacy with consistent use, which could impact motivation to seek out PrEP for HIV prevention. Targeted messaging to increase PrEP knowledge may increase PrEP use. PMID:29362213

AucPR: an AUC-based approach using penalized regression for disease prediction with high-dimensional omics data.

PubMed

Yu, Wenbao; Park, Taesung

2014-01-01

It is common to get an optimal combination of markers for disease classification and prediction when multiple markers are available. Many approaches based on the area under the receiver operating characteristic curve (AUC) have been proposed. Existing works based on AUC in a high-dimensional context depend mainly on a non-parametric, smooth approximation of AUC, with no work using a parametric AUC-based approach, for high-dimensional data. We propose an AUC-based approach using penalized regression (AucPR), which is a parametric method used for obtaining a linear combination for maximizing the AUC. To obtain the AUC maximizer in a high-dimensional context, we transform a classical parametric AUC maximizer, which is used in a low-dimensional context, into a regression framework and thus, apply the penalization regression approach directly. Two kinds of penalization, lasso and elastic net, are considered. The parametric approach can avoid some of the difficulties of a conventional non-parametric AUC-based approach, such as the lack of an appropriate concave objective function and a prudent choice of the smoothing parameter. We apply the proposed AucPR for gene selection and classification using four real microarray and synthetic data. Through numerical studies, AucPR is shown to perform better than the penalized logistic regression and the nonparametric AUC-based method, in the sense of AUC and sensitivity for a given specificity, particularly when there are many correlated genes. We propose a powerful parametric and easily-implementable linear classifier AucPR, for gene selection and disease prediction for high-dimensional data. AucPR is recommended for its good prediction performance. Beside gene expression microarray data, AucPR can be applied to other types of high-dimensional omics data, such as miRNA and protein data.

Scutellarin-graft cationic β-cyclodextrin-polyrotaxane: Synthesis, characterization and DNA condensation.

PubMed

Qin, Qi; Ma, Xue; Liao, Xiali; Yang, Bo

2017-02-01

As a prerequisite of gene delivery in living cells, DNA condensation has attracted more and more attention. In order to improve the efficiencies of polyamine-β-cyclodextrin-based cationic polyrotaxanes (PR-EDA and PR-DETA) as DNA condensation materials, we have designed and prepared two novel scutellarin-grafted cationic polyrotaxanes (PR-EDA-SCU and PR-DETA-SCU), in which scutellarins (SCU), the planar molecules, were conjugated on the cyclodextrin molecules of PR-EDA and PR-DETA. These materials were characterized by 1D and 2D NMR, XRD, TG and DSC. The electrophoresis assays showed that pDNA condensation efficiencies of PR-EDA and PR-DETA were better than that of PR-EDA and PR-DETA. The complexes of PR-EDA, PR-DETA, PR-EDA-SCU and PR-DETA-SCU with pDNA were further investigated by zeta potential and atomic force microscopy analysis. The results indicated that the planar structure of SCU played an important role in improvement of pDNA condensation efficiencies of PR-EDA-SCU and PR-DETA-SCU. The satisfactory pDNA condensation abilities of PR-EDA-SCU and PR-DETA-SCU could be helpful in designing non-viral gene delivery vectors to control gene expression and delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

Divergent prion strain evolution driven by PrPC expression level in transgenic mice

PubMed Central

Le Dur, Annick; Laï, Thanh Lan; Stinnakre, Marie-George; Laisné, Aude; Chenais, Nathalie; Rakotobe, Sabine; Passet, Bruno; Reine, Fabienne; Soulier, Solange; Herzog, Laetitia; Tilly, Gaëlle; Rézaei, Human; Béringue, Vincent; Vilotte, Jean-Luc; Laude, Hubert

2017-01-01

Prions induce a fatal neurodegenerative disease in infected host brain based on the refolding and aggregation of the host-encoded prion protein PrPC into PrPSc. Structurally distinct PrPSc conformers can give rise to multiple prion strains. Constrained interactions between PrPC and different PrPSc strains can in turn lead to certain PrPSc (sub)populations being selected for cross-species transmission, or even produce mutation-like events. By contrast, prion strains are generally conserved when transmitted within the same species, or to transgenic mice expressing homologous PrPC. Here, we compare the strain properties of a representative sheep scrapie isolate transmitted to a panel of transgenic mouse lines expressing varying levels of homologous PrPC. While breeding true in mice expressing PrPC at near physiological levels, scrapie prions evolve consistently towards different strain components in mice beyond a certain threshold of PrPC overexpression. Our results support the view that PrPC gene dosage can influence prion evolution on homotypic transmission. PMID:28112164

An open and configurable embedded system for EMG pattern recognition implementation for artificial arms.

PubMed

Jun Liu; Fan Zhang; Huang, He Helen

2014-01-01

Pattern recognition (PR) based on electromyographic (EMG) signals has been developed for multifunctional artificial arms for decades. However, assessment of EMG PR control for daily prosthesis use is still limited. One of the major barriers is the lack of a portable and configurable embedded system to implement the EMG PR control. This paper aimed to design an open and configurable embedded system for EMG PR implementation so that researchers can easily modify and optimize the control algorithms upon our designed platform and test the EMG PR control outside of the lab environments. The open platform was built on an open source embedded Linux Operating System running a high-performance Gumstix board. Both the hardware and software system framework were openly designed. The system was highly flexible in terms of number of inputs/outputs and calibration interfaces used. Such flexibility enabled easy integration of our embedded system with different types of commercialized or prototypic artificial arms. Thus far, our system was portable for take-home use. Additionally, compared with previously reported embedded systems for EMG PR implementation, our system demonstrated improved processing efficiency and high system precision. Our long-term goals are (1) to develop a wearable and practical EMG PR-based control for multifunctional artificial arms, and (2) to quantify the benefits of EMG PR-based control over conventional myoelectric prosthesis control in a home setting.

Reducing hospital-acquired pressure ulcers with a silicone-based dermal nourishing emollient-associated skincare regimen.

PubMed

Shannon, Ronald J; Coombs, Martha; Chakravarthy, Debashish

2009-10-01

To determine the effect of a silicone-based dermal nourishing emollient (SBDNE) regimen on the reduction of pressure ulcers (PrUs) and costs in a hospital medical unit. PrUs represent a serious problem for patients within the acute care setting and are a significant care management challenge for clinicians. Effective October 1, 2008, the Centers for Medicare and Medicaid Services will no longer reimburse hospitals at the higher diagnosis-related group rate for Stages III and IV PrUs that are not documented on admission. In addition, formation of PrUs in the hospital also puts the institution at financial risk of lawsuits. The wound healing center at Porter Adventist Hospital, Denver, Colorado, documented the hospital-acquired incidence rate of PrU patients in the hospital from May 2006 to December 2007. A retrospective, quasi-experimental design was used to examine the changes in PrU incidence rates and the economic effect of introducing a SBDNE regimen into an existing PrU prevention protocol. The replacement of a mixture of ad hoc skin care products, none of which contained silicone-based emollients, with an SBDNE skin care regimen into an existing prevention program significantly reduced the proportion of hospital-acquired PrUs to 0% after 8 months. Estimated cost savings per patient admitted to the medical unit attributed to SBDNE averaged $6677.11 per patient. The use of an SBDNE skin care regimen was important in bringing about a significant reduction in the number of patients with PrUs and respective treatment costs in a medical unit experiencing high incidence rates of PrUs.

Palladium(II) complexes with highly basic imidazolin-2-imines and their reactivity toward small bio-molecules.

PubMed

Bogojeski, Jovana; Volbeda, Jeroen; Freytag, Matthias; Tamm, Matthias; Bugarčić, Živadin D

2015-10-21

A series of novel Pd(ii) complexes with chelating mono(imidazolin-2-imine) and bis(imidazolin-2-imine) ligands were synthesized. The crystal structures of [Pd(DMEAIm(iPr))Cl2] and [Pd(DPENIm(iPr))Cl2] were determined by X-ray diffraction analysis. The reactivity of the six Pd(ii) complexes, namely, [Pd(en)Cl2], [Pd(EAIm(iPr))Cl2], [Pd(DMEAIm(iPr))Cl2], [Pd(DPENIm(iPr))Cl2], [Pd(BL(iPr))Cl2] and [Pd(DACH(Im(iPr))2)Cl2], were investigated. Spectrophotometric acid-base titrations were performed to determine the pKa values of the coordinated water molecules in [Pd(en)(H2O)2](2+), [Pd(EAIm(iPr))(H2O)2](2+), [Pd(DMEAIm(iPr))(H2O)2](2+), [Pd(DPENIm(iPr))(H2O)2](2+), [Pd(BL(iPr))(H2O)2](2+) and [Pd(DACH(Im(iPr))2)(H2O)2](2+). The substitution of the chloride ligands in these complexes by TU, l-Met, l-His and Gly was studied under pseudo-first-order conditions as a function of the nucleophile concentration and temperature using stopped-flow techniques; the sulfur-donor nucleophiles have shown better reactivity than nitrogen-donor nucleophiles. The obtained results indicate that there is a clear correlation between the nature of the imidazolin-2-imine ligands and the acid-base characteristics and reactivity of the resulting Pd(ii) complexes; the order of reactivity of the investigated Pd(ii) complexes is: [Pd(en)Cl2] > [Pd(EAIm(iPr))Cl2] > [Pd(DMEAIm(iPr))Cl2] > [Pd(DPENIm(iPr))Cl2] > [Pd(BL(iPr))Cl2] > [Pd(DACH(Im(iPr))2)Cl2]. The solubility measurements revealed good solubility of the studied imidazolin-2-imine complexes in water, despite the fact that these Pd(ii) complexes are neutral complexes. Based on the performed studies, three unusual features of the novel imidazolin-2-imine Pd(ii) complexes are observed, that is, good solubility in water, very low reactivity and high pKa values. The coordination geometries around the palladium atoms are distorted square-planar; the [Pd(DMEAIm(iPr))Cl2] complex displays Pd-N distances of 2.013(2) and 2.076(2) Å, while the [Pd(DPENIm(iPr))Cl2] complex displays similar Pd-N distances of 2.034(4) and 2.038(3) Å. The studied systems are of interest because little is known about the substitution behavior of imidazolin-2-imine Pd(ii) complexes with bio-molecules under physiological conditions.

Identification and characterisation of seventeen glutathione S-transferase genes from the cabbage white butterfly Pieris rapae.

PubMed

Liu, Su; Zhang, Yu-Xing; Wang, Wen-Long; Zhang, Bang-Xian; Li, Shi-Guang

2017-11-01

Insect glutathione S-transferases (GSTs) play essential roles in the detoxification of insecticides and other xenobiotic compounds. The cabbage white butterfly, Pieris rapae, is an economically important agricultural pest. In this study, 17 cDNA sequences encoding putative GSTs were identified in P. rapae. All cDNAs include a complete open reading frame and were designated PrGSTd1-PrGSTz2. Based on phylogenetic analysis, PrGSTs were divided into six classes (delta, epsilon, omega, sigma, theta and zeta). The exon-intron organizations of these PrGSTs were also analysed. Recombinant proteins of eight PrGSTs (PrGSTD1, PrGSTD2, PrGSTE1, PrGSTE2, PrGSTO1, PrGSTS1, PrGSTT1 and PrGSTZ1) were heterologously expressed in Escherichia coli, and all of these proteins displayed glutathione-conjugating activity towards 1-chloro-2,4-dinitrobenzene (CDNB). Expression patterns in various larval tissues, at different life stages, and following exposure to sublethal doses of abamectin, chlorantraniliprole or lambda-cyhalothrin were determined by reverse transcription-quantitative PCR. The results showed that PrGSTe3, PrGSTs1, PrGSTs2, and PrGSTs4 were mainly transcribed in the fat body, while PrGSTe2 was expressed predominantly in the Malpighian tubules. Four genes (PrGSTe2, PrGSTo4, PrGSTs4 and PrGSTt1) were mainly expressed in fourth-instar larvae, while others were ubiquitously expressed in egg, larval, pupa and/or adult stages. Abamectin treatment significantly upregulated ten genes (PrGSTd1, PrGSTd3, PrGSTe1, PrGSTe2, PrGSTo1, PrGSTo3, PrGSTs1, PrGSTs3, PrGSTs4 and PrGSTt1). Chlorantraniliprole and lambda-cyhalothrin treatment significantly upregulated nine genes (PrGSTd1, PrGSTd2, PrGSTe1, PrGSTe2, PrGSTe3, PrGSTs1, PrGSTs3, PrGSTs4 and PrGSTz1) and ten genes (PrGSTd1, PrGSTd3, PrGSTe1, PrGSTe2, PrGSTo1, PrGSTo2, PrGSTs1, PrGSTs2, PrGSTs3 and PrGSTz2), respectively. These GSTs are potentially involved in the detoxification of insecticides. Copyright © 2017 Elsevier Inc. All rights reserved.

Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification.

PubMed

Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

2016-07-07

Prions are formed of misfolded assemblies (PrP(Sc)) of the variably N-glycosylated cellular prion protein (PrP(C)). In infected species, prions replicate by seeding the conversion and polymerization of host PrP(C). Distinct prion strains can be recognized, exhibiting defined PrP(Sc) biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrP(Sc) assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrP(C) glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrP(C) species of interest as substrate. Applying the technique to PrP(C) glycosylation mutants expressing cells revealed that neither PrP(C) nor PrP(Sc) glycoform stoichiometry was instrumental to PrP(Sc) formation and strainness perpetuation. Our study supports the view that strain properties, including PrP(Sc) glycotype are enciphered within PrP(Sc) structural backbone, not in the attached glycans.

High Efficiency Thermoelectric Radioisotope Power Systems

NASA Technical Reports Server (NTRS)

El-Genk, Mohamed; Saber, Hamed; Caillat, Thierry

2004-01-01

The work performed and whose results presented in this report is a joint effort between the University of New Mexico s Institute for Space and Nuclear Power Studies (ISNPS) and the Jet Propulsion Laboratory (JPL), California Institute of Technology. In addition to the development, design, and fabrication of skutterudites and skutterudites-based segmented unicouples this effort included conducting performance tests of these unicouples for hundreds of hours to verify theoretical predictions of the conversion efficiency. The performance predictions of these unicouples are obtained using 1-D and 3-D models developed for that purpose and for estimating the actual performance and side heat losses in the tests conducted at ISNPS. In addition to the performance tests, the development of the 1-D and 3-D models and the development of Advanced Radioisotope Power systems for Beginning-Of-Life (BOM) power of 108 We are carried out at ISNPS. The materials synthesis and fabrication of the unicouples are carried out at JPL. The research conducted at ISNPS is documented in chapters 2-5 and that conducted at JP, in documented in chapter 5. An important consideration in the design and optimization of segmented thermoelectric unicouples (STUs) is determining the relative lengths, cross-section areas, and the interfacial temperatures of the segments of the different materials in the n- and p-legs. These variables are determined using a genetic algorithm (GA) in conjunction with one-dimensional analytical model of STUs that is developed in chapter 2. Results indicated that when optimized for maximum conversion efficiency, the interfacial temperatures between various segments in a STU are close to those at the intersections of the Figure-Of-Merit (FOM), ZT, curves of the thermoelectric materials of the adjacent segments. When optimizing the STUs for maximum electrical power density, however, the interfacial temperatures are different from those at the intersections of the ZT curves, but close to those at the intersections the characteristic power, CP, curves of the thermoelectric materials of the adjacent segments (CP = T(sup 2)Zk and has a unit of W/m). Results also showed that the number of the segments in the n- and p-legs of the STUs optimized for maximum power density are generally fewer than when the same unicouples are optimized for maximum efficiency. These results are obtained using the 1-D optimization model of STUs that is detailed in chapter 2. A three-dimensional model of STUs is developed and incorporated into the ANSYS commercial software (chapter 3). The governing equations are solved, subject to the prescribed

Covalent surface modification of prions: a mass spectrometry-based means of detecting distinctive structural features of prion strains

USDA-ARS?s Scientific Manuscript database

Prions (PrPSc) are molecular pathogens that are able to convert the isosequential normal cellular prion protein (PrPC) into a prion. The only demonstrated differences between PrPC and PrPSc is conformational, they are isoforms. A given host can be infected by more than one kind or strain of prion. F...

“Life-Steps” for PrEP Adherence: Demonstration of a CBT-Based Intervention to Increase Adherence to Preexposure Prophylaxis (PrEP) Medication Among Sexual-Minority Men at High Risk for HIV Acquisition

PubMed Central

Taylor, S. Wade; Psaros, Christina; Pantalone, David W.; Tinsley, Jake; Elsesser, Steven A.; Mayer, Kenneth H.; Safren, Steven A.

2016-01-01

One dramatic advance in human immunodeficiency virus (HIV) prevention efforts has been the prescription of medications typically used for HIV treatment as prophylaxis against acquiring HIV. As a preventative agent, this practice is referred to as “preexposure prophylaxis” (PrEP). The U.S. Federal Drug Administration approved daily PrEP for adults at risk for HIV who do not consistently use condoms during sex with HIV-infected or unknown-status partners. In this paper, we describe a cognitive-behavioral therapy (CBT) PrEP adherence intervention developed for use in high-risk sexual-minority men in the United States, adapted from “Life-Steps,” an evidence-based CBT intervention to promote adherence to HIV treatment. Modules include creating a PrEP dosing schedule, adhering to daily PrEP, problem solving barriers to adherence, and sexual risk-reduction techniques. Supplemented with practical video vignettes, this novel intervention may help to enhance the clinical practice of health care providers in outpatient settings to increase PrEP adherence in sexual-minority men. PMID:28392673

A novel capture-ELISA for detection of anti-neutrophil cytoplasmic antibodies (ANCA) based on c-myc peptide recognition in carboxy-terminally tagged recombinant neutrophil serine proteases.

PubMed

Lee, Augustine S; Finkielman, Javier D; Peikert, Tobias; Hummel, Amber M; Viss, Margaret A; Specks, Ulrich

2005-12-20

Testing for antineutrophil cytoplasmic antibodies (ANCA) reacting with proteinase 3 (PR3) is part of the routine diagnostic evaluation of patients with small vessel vasculitis. For PR3-ANCA detection, capture ELISAs are reported to be superior to direct ELISAs. Standard capture ELISAs, in which PR3 is anchored by anti-PR3 monoclonal antibodies (moAB), have two potential disadvantages. First, the capturing moAB may compete for epitopes recognized by some PR3-ANCA, causing occasional false-negative results. Second, the capture of recombinant PR3 mutant molecules becomes unpredictable as modifications of specific conformational epitopes may not only affect the binding of PR3-ANCA, but also the affinity of the capturing anti-PR3 moAB. Here, we describe a new capture ELISA, and its application for PR3-ANCA detection. This new assay is based on the standardized capture of a variety of different carboxy-terminally c-myc tagged recombinant ANCA target antigens using anti-c-myc coated ELISA plates. Antigen used include c-myc tagged human rPR3 variants (mature and pro-form conformations), mouse mature rPR3 and human recombinant neutrophil elastase. This new anti-c-myc-capture ELISA for PR3-ANCA detection has an intra- and inter-assay coefficient of variation of 3.6% to 7.7%, and 15.8% to 18.4%, respectively. The analytical sensitivity and specificity for PR3-ANCA positive serum samples were 93% and 100%, respectively when rPR3 with mature conformation was used as target antigen, and 83% and 100% when the pro-enzyme conformation was employed. In conclusion, this new anti-c-myc capture ELISA compares favorably to our standard capture ELISA for PR3-ANCA detection, enables the unified capture of different ANCA target antigens through binding to a c-myc tag, and allows capture of rPR3 mutants necessary for PR3-ANCA epitope mapping studies.

Pulmonary Rehabilitation in Ontario: A Cross-Sectional Survey

PubMed Central

Bowen, James M; Campbell, Kaitryn; Sutherland, Simone; Bartlett, Ann; Brooks, Dina; Qureshi, Riaz; Goldstein, Roger; Gershon, Andrea S; Prevost, Shelley; Samis, Lorelei; Kaplan, Alan G; Hopkins, Robert B; MacDougald, Craig; Nunes, Erica; O'Reilly, Daria J; Goeree, Ron

2015-01-01

Background Pulmonary rehabilitation (PR) is a comprehensive intervention of exercise training, education, and behaviour change to improve the physical and psychological condition of people with chronic respiratory disorders, such as chronic obstructive pulmonary disease (COPD) and to promote long-term adherence to health-enhancing behaviours. Although PR is considered the standard of care for patients with COPD who remain symptomatic despite bronchodilator therapies, current evidence suggests that only 1.15% of COPD patients across Canada have access to PR facilities for care. Objectives The objectives of this study were to identify the number of health care facilities across Ontario providing PR services for patients with COPD, describe the scope of those services, and determine the province's current capacity to provide PR services relative to need, for the province as a whole and by local health integration network (LHIN). Methods The Pulmonary Rehabilitation Programs in Ontario (PRO) Survey was a province-wide, descriptive, cross-sectional survey of health care facilities (hospitals, family health teams, and community health centres). It was distributed to 409 facilities to collect information on various aspects of PR services in the province. Results Between April 2013 and February 2014, 187 facilities responded to the survey (46% response rate). Most responding centres (144) did not offer PR services, and only 43 were full PR sites providing a comprehensive program. Hospital-based programs made up the majority of sites offering full PR services (67%), followed by programs based at family health teams (19%) and community health centres (14%). More than 90% of PR programs are outpatient-based. The average wait time for outpatient PR was 6.9 weeks, and 58% of programs provide services 5 days per week. More than 80% of patients attending PR complete the full program. Across all program types, the total estimated provincial capacity for PR outpatient care is 4,524 patients per year, or 0.66% to 1.78% of patients with COPD, depending on the estimated prevalence of disease. Limitations These results are representative of 12 of the 14 LHINs in Ontario due to low response rates in facilities in 2 LHINs. Conclusions Although some increase in capacity has occurred since a similar survey in 2005, PR resources in Ontario are insufficient to support the delivery of care to people with COPD in accordance with clinical practice guideline recommendations. PMID:26366242

A compact proton spectrometer for measurement of the absolute DD proton spectrum from which yield and pR are determined in thin-shell inertial-confinement-fusion implosions

DOE PAGES

Rosenberg, M. J.; Zylstra, A. B.; Frenje, J. A.; ...

2014-10-10

A compact, step range filter proton spectrometer has been developed for the measurement of the absolute DD proton spectrum, from which yield and areal density (ρR) are inferred for deuterium-filled thin-shell inertial confinement fusion implosions. This spectrometer, which is based on tantalum step-range filters, is sensitive to protons in the energy range 1-9 MeV and can be used to measure proton spectra at mean energies of ~1-3 MeV. It has been developed and implemented using a linear accelerator and applied to experiments at the OMEGA laser facility and the National Ignition Facility (NIF). Modeling of the proton slowing in themore » filters is necessary to construct the spectrum, and the yield and energy uncertainties are ±<10% in yield and ±120 keV, respectively. This spectrometer can be used for in situ calibration of DD-neutron yield diagnostics at the NIF« less

Sequence quality analysis tool for HIV type 1 protease and reverse transcriptase.

PubMed

Delong, Allison K; Wu, Mingham; Bennett, Diane; Parkin, Neil; Wu, Zhijin; Hogan, Joseph W; Kantor, Rami

2012-08-01

Access to antiretroviral therapy is increasing globally and drug resistance evolution is anticipated. Currently, protease (PR) and reverse transcriptase (RT) sequence generation is increasing, including the use of in-house sequencing assays, and quality assessment prior to sequence analysis is essential. We created a computational HIV PR/RT Sequence Quality Analysis Tool (SQUAT) that runs in the R statistical environment. Sequence quality thresholds are calculated from a large dataset (46,802 PR and 44,432 RT sequences) from the published literature ( http://hivdb.Stanford.edu ). Nucleic acid sequences are read into SQUAT, identified, aligned, and translated. Nucleic acid sequences are flagged if with >five 1-2-base insertions; >one 3-base insertion; >one deletion; >six PR or >18 RT ambiguous bases; >three consecutive PR or >four RT nucleic acid mutations; >zero stop codons; >three PR or >six RT ambiguous amino acids; >three consecutive PR or >four RT amino acid mutations; >zero unique amino acids; or <0.5% or >15% genetic distance from another submitted sequence. Thresholds are user modifiable. SQUAT output includes a summary report with detailed comments for troubleshooting of flagged sequences, histograms of pairwise genetic distances, neighbor joining phylogenetic trees, and aligned nucleic and amino acid sequences. SQUAT is a stand-alone, free, web-independent tool to ensure use of high-quality HIV PR/RT sequences in interpretation and reporting of drug resistance, while increasing awareness and expertise and facilitating troubleshooting of potentially problematic sequences.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heaslet, H.; Lin, Y.-C.; Tam, K.

We have obtained the 1.7 angstrom crystal structure of FIV protease (PR) in which 12 critical residues around the active site have been substituted with the structurally equivalent residues of HIV PR (12X FIV PR). The chimeric PR was crystallized in complex with the broad-based inhibitor TL-3, which inhibits wild type FIV and HIV PRs, as well as 12X FIV PR and several drug-resistant HIV mutants [1-4]. Biochemical analyses have demonstrated that TL-3 inhibits these PRs in the order HIV PR > 12X FIV PR > FIV PR, with Ki values of 1.5 nM, 10 nM, and 41 nM, respectivelymore » [2-4]. Comparison of the crystal structures of the TL-3 complexes of 12X FIV and wild-typeFIV PR revealed the formation of additional van der Waals interactions between the enzyme inhibitor in the mutant PR. The 12X FIV PR retained the hydrogen bonding interactions between residues in the flap regions and active site involving the enzyme and the TL-3 inhibitor in comparison to both FIV PR and HIV PR. However, the flap regions of the 12X FIV PR more closely resemble those of HIV PR, having gained several stabilizing intra-flap interactions not present in wild type FIV PR. These findings offer a structural explanation for the observed inhibitor/substrate binding properties of the chimeric PR.« less

Phylogenetic analysis of PR genes in some pome fruit species with the emphasis on transcriptional analysis and ROS response under Erwinia amylovora inoculation in apple.

PubMed

Hassani, Maryam; Salami, Seyed Alireza; Nasiri, Jaber; Abdollahi, Hamid; Ghahremani, Zahra

2016-02-01

Attempts were made to identify eight pathogenesis related (PR) genes (i.e., PR-1a, PR3-ch1, PR3-Ch2, PR3-Ch3, PR3-Ch4, PR3-Ch5, PR-5 and PR-8) from 27 genotypes of apple, quince and pear, which are induced in response to inoculation with the pathogen Erwinia amylovora, the causal agent of fire blight. Totally, 32 PR genes of different families were obtained, excepting PR3-Ch2 (amplified only in apple) and PR3-Ch4 (amplified only in apple and pear), the others were successfully amplified in all the genotypes of apple, quince and pear. Evolutionary, the genes of each family exhibited significant homology with each other, as the corresponded phylogenetic neighbor-joining-based dendrograms were taken into consideration. Meanwhile, according to the expression assay, it was deduced that the pathogen activity can significantly affect the expression levels of some selected PR genes of PR3-Ch2, PR3-Ch4, PR3-Ch5 and particularly Cat I in both resistant (MM-111) and semi-susceptible (MM-106) apple rootstocks. Lastly, it was concluded that the pathogen E. amylovora is able to stimulate ROS response, particularly using generation of hydrogen peroxide (H2O2) in both aforementioned apple rootstock.

Fragment-based protein-protein interaction antagonists of a viral dimeric protease

PubMed Central

Gable, Jonathan E.; Lee, Gregory M.; Acker, Timothy M.; Hulce, Kaitlin R.; Gonzalez, Eric R.; Schweigler, Patrick; Melkko, Samu; Farady, Christopher J.; Craik, Charles S.

2016-01-01

Fragment-based drug discovery has shown promise as an approach for challenging targets such as protein-protein interfaces. We developed and applied an activity-based fragment screen against dimeric Kaposi’s sarcoma-associated herpesvirus protease (KSHV Pr) using an optimized fluorogenic substrate. Dose response determination was performed as a confirmation screen and NMR spectroscopy was used to map fragment inhibitor binding to KSHV Pr. Kinetic assays demonstrated that several initial hits also inhibit human cytomegalovirus protease (HCMV Pr). Binding of these hits to HCMV Pr was also confirmed via NMR spectroscopy. Despite the use of a target-agnostic fragment library, more than 80% of confirmed hits disrupted dimerization and bound to a previously reported pocket at the dimer interface of KSHV Pr, not to the active site. One class of fragments, an aminothiazole scaffold, was further explored using commercially available analogs. These compounds demonstrated greater than 100-fold improvement of inhibition. This study illustrates the power of fragment-based screening for these challenging enzymatic targets and provides an example of the potential druggability of pockets at protein-protein interfaces. PMID:26822284

Intelligent ePR system for evidence-based research in radiotherapy: proton therapy for prostate cancer.

PubMed

Le, Anh H; Liu, Brent; Schulte, Reinhard; Huang, H K

2011-11-01

Proton therapy (PT) utilizes high energy particle proton beam to kill cancer cells at the target region for target cancer therapy. Due to the physical properties of the proton beam, PT delivers dose with higher precision and no exit dose compared to conventional radiotherapy. In PT, patient data are distributed among multiple systems, a hindrance to research on efficacy and effectiveness. A data mining method and a treatment plan navigator utilizing the infrastructure and data repository of a PT electronic patient record (ePR) was developed to minimize radiation toxicity and improve outcomes in prostate cancer treatment. MATERIALS/METHOD(S): The workflow of a proton therapy treatment in a radiation oncology department was reviewed, and a clinical data model and data flow were designed. A prototype PT ePR system with DICOM compliance was developed to manage prostate cancer patient images, treatment plans, and related clinical data. The ePR system consists of four main components: (1) Data Gateway; (2) ePR Server; (3) Decision Support Tools; and (4) Visualization and Display Tools. Decision support and visualization tools are currently developed based on DICOM images, DICOM-RT and DICOM-RT-ION objects data from prostate cancer patients treated with hypofractionation protocol proton therapy were used for evaluating ePR system effectiveness. Each patient data set includes a set of computed tomography (CT) DICOM images and four DICOM-RT and RT-ION objects. In addition, clinical outcomes data collected from PT cases were included to establish a knowledge base for outcomes analysis. A data mining search engine and an intelligent treatment plan navigator (ITPN) were developed and integrated with the ePR system. Evaluation was based on a data set of 39 PT patients and a hypothetical patient. The ePR system was able to facilitate the proton therapy workflow. The PT ePR system was feasible for prostate cancer patient treated with hypofractionation protocol in proton therapy. This ePR system improves efficiency in data collection and integration to facilitate outcomes analysis.

Potential approaches for heterologous prion protein treatment of prion diseases

PubMed Central

Seelig, Davis M.; Goodman, Patricia A.; Skinner, Pamela J.

2016-01-01

ABSTRACT Prion diseases, or transmissible spongiform encephalopathies (TSEs) are progressive, fatal neurodegenerative diseases with no effective treatment. The pathology of these diseases involves the conversion of a protease sensitive form of the cellular prion protein (PrPC) into a protease resistant infectious form (PrPres). The efficiency of this conversion is predicated upon a number of factors, most notably a strong homology between cellular PrPC and PrPres. In our recently published study, we infected mice with the RML-Chandler strain of scrapie and treated them with heterologous hamster prion proteins. This treatment was seen to reduce clinical signs of prion disease, to delay the onset of clinical symptoms and to prolong survival. In this current article we discuss potential mechanisms of action of treatment with heterologous prion proteins. We also discuss potential extensions of these studies using a heterologous rabbit PrP-based treatment strategy or a peptide based strategy, and improvement of treatment delivery including a lentiviral-based system. PMID:26636482

Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

PubMed

Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

2010-04-07

The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

Antibacterial Properties Associated with Chitosan Nanoparticle Treatment on Root Dentin and 2 Types of Endodontic Sealers.

PubMed

Del Carpio-Perochena, Aldo; Kishen, Anil; Shrestha, Annie; Bramante, Clovis Monteiro

2015-08-01

The aim of this study was to evaluate the efficacy of carboxymethyl chitosan (CMCS) and chitosan nanoparticles (CNps) to inactivate bacteria and prevent biofilm formation at sealer-dentin interfaces. The study was divided into 3 stages: first stage, the experiment was conducted to analyze the antibacterial properties of CMCS in different formulations against biofilms; second stage, direct-contact and membrane-restricted methods were used to evaluate the antibacterial properties of an epoxy resin (ThermaSeal Plus; Dentsply Tulsa Dental, Tulsa, OK) and calcium silicate (MTA Fillapex; Angelus SA, Londrina, PR, Brazil) based-sealers with or without CNps; and third stage, biofilm formation at the sealer dentin interfaces of root dentin treated with CMCS and filled with gutta-percha and CNp incorporated sealer were analyzed after 1- and 4-week aging periods. The samples were treated and filled as follows: (1) distilled water: unaltered sealer (control group), (2) CMCS: sealer+CNps (CMCS group), and (3) CMCS/rose bengal: sealer+CNps (CMCS/RB group). Enterococcus faecalis was used to infect all the samples. Microbiological and microscopic analyses were used to assess the antibacterial characteristics. CMCS-based treatments effectively killed bacteria adherent on root dentin (P < .05). The addition of CNps to ThermaSeal enhanced its antibacterial ability by direct-contact and membrane-restricted tests (P < .05). The CNp incorporation significantly increased the antibacterial efficacy of root canal sealers even after a 4-week aging time (P < .05). This study highlighted the ability of CMCS to disinfect root canal dentin and inhibit bacterial adhesion. CNps in root canal sealers are capable of maintaining their antibacterial activity even after prolonged aging. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Real-life feasibility and effectiveness of home-based pulmonary rehabilitation in chronic obstructive pulmonary disease requiring medical equipment.

PubMed

Coquart, Jérémy B; Le Rouzic, Olivier; Racil, Ghazi; Wallaert, Benoit; Grosbois, Jean-Marie

2017-01-01

Pulmonary rehabilitation (PR) is a key treatment of chronic obstructive pulmonary disease (COPD) but studies are still needed to identify the most pertinent criteria to personalize this intervention and improve its efficacy. This real-life retrospective study compared the effects of home-based PR on exercise tolerance, anxiety, depression, and health-related quality of life (HRQoL) in COPD patients, according to their medical equipment. Exercise tolerance, anxiety, depression, and HRQoL were evaluated in 109 patients equipped with long-term oxygen therapy (LTOT), 84 patients with noninvasive ventilation (NIV), 25 patients with continuous positive airway pressure (CPAP), and 80 patients with no equipment (NE), before, just after, and 6 and 12 months after PR. At baseline, the body mass index in the CPAP and NIV groups was higher ( p <0.05) than in the other two groups, and the forced expiratory volume in 1 second was lower in the LTOT and NIV groups ( p <0.001). All parameters improved after PR in the four groups ( p <0.05), but for exercise tolerance, only the 6-minute stepper test showed maintained improvement after 6 and 12 months, whereas the 10 times sit-to-stand and timed up-and-go tests were only improved just after PR. At every time point, exercise tolerance was lower in the LTOT group ( p <0.05), with a similar trend in the NIV group. Despite differences in the medical equipment to treat COPD, home-based PR showed comparable feasibility, safety, and efficacy in all equipment-based groups. Medical equipment should therefore not be a barrier to home-based PR.

Development of an Influenza A Master Virus for Generating High-Growth Reassortants for A/Anhui/1/2013(H7N9) Vaccine Production in Qualified MDCK Cells

PubMed Central

Suzuki, Yasushi; Odagiri, Takato; Tashiro, Masato; Nobusawa, Eri

2016-01-01

In 2013, the first case of human infection with an avian influenza A virus (H7N9) was reported in China, and the human infection with this virus has continued as of 2016. At the request of the WHO, we have successfully developed candidate reassortant vaccine virus using A/Anhui/1/2013 and the high egg-growth master virus A/PR/8/1934. Recent plans regarding influenza vaccine production include using cell-cultured systems in Japan and several other countries. However, egg-based vaccine viruses are not always suitable for cell-cultured vaccine production due to potential issues with growth, protein yield and antigenic stability. Therefore, in this study, we have developed a high-growth master virus (hg-PR8) adapted to qualified NIID-MDCK cells that are competent for vaccine production. The virus hg-PR8 was obtained after 20 serial passages of A/Puerto Rico/8/1934 (PR8) in NIID-MDCK cells. The viral titer of hg-PR8 was 108.6 plaque-forming units per milliliter (PFU/mL). Seven amino acid substitutions were identified in the amino acid sequences of PB2, PB1, PA, NA, M and NS of hg-PR8 compared to the sequence of the original PR8 (org-PR8) strain. The growth capacities of the reassortant viruses, which possess heterologous internal genes from hg-PR8 or org-PR8, indicated that the amino acid changes in PB2 and NS2 similarly affected growth capacity in NIID-MDCK cells. To assess the suitability of hg-PR8 as a master virus, we generated 6:2 reassortant viruses possessing the HA and NA segments from A/Anhui/1/2013 (H7N9) and the remaining segments from hg-PR8. The virus titers of the reassortant strains were 107−108 PFU/mL. The antigenicity of the viruses was stable during ten passages of the viruses in NIID-MDCK cells. In comparison with the egg-based reassortant vaccine viruses with identical HA and NA segments, the hg-PR8-based viruses showed 1.5- to 2-fold higher protein yields in NIID-MDCK cells. PMID:27454606

The down-conversion and up-conversion photoluminescence properties of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}:Yb{sup 3+}/Pr{sup 3+} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yinpeng; Luo, Laihui, E-mail: luolaihui@nbu.edu.cn; Wang, Jia

2015-07-28

Na{sub 0.5}Bi{sub 0.5−x−y}Yb{sub x}Pr{sub y}TiO{sub 3} (NBT:xYb/yPr) ceramics with different Yb and Pr contents are prepared. Both the down-conversion (DC) and up-conversion (UC) photoluminescence (PL) of the ceramics via 453 and 980 nm excitation, respectively, are investigated. The effect of Yb{sup 3+} and Pr{sup 3+} doping contents on the DC and UC PL is significantly different from each other. Furthermore, the UC PL of the ceramics as a function of temperatures is measured to investigate the UC process in detail. Based on energy level diagram of Pr{sup 3+} and Yb{sup 3+} ions and the DC and UC PL spectra, the DCmore » and UC PL mechanisms of Pr{sup 3+} and Yb{sup 3+} ions are discussed. Especially, the UC PL mechanism is clarified, which is different from the previously reported literature. Also, the temperature sensing properties of the ceramics are studied based on the photoluminescence ratio technique, using the thermal coupling energy levels of Pr{sup 3+}.« less

Shift and rotation invariant photorefractive crystal-based associative memory

NASA Astrophysics Data System (ADS)

Uang, Chii-Maw; Lin, Wei-Feng; Lu, Ming-Huei; Lu, Guowen; Lu, Mingzhe

1995-08-01

A shift and rotation invariant photorefractive (PR) crystal based associative memory is addressed. The proposed associative memory has three layers: the feature extraction, inner- product, and output mapping layers. The feature extraction is performed by expanding an input object into a set of circular harmonic expansions (CHE) in the Fourier domain to acquire both the shift and rotation invariant properties. The inner product operation is performed by taking the advantage of Bragg diffraction of the bulky PR-crystal. The output mapping is achieved by using the massive storage capacity of the PR-crystal. In the training process, memories are stored in another PR-crystal by using the wavelength multiplexing technique. During the recall process, the output from the winner-take-all processor decides which wavelength should be used to read out the memory from the PR-crystal.

Magnetic and thermodynamic properties of the Pr-based ferromagnet PrGe2-δ

NASA Astrophysics Data System (ADS)

Matsumoto, Keisuke T.; Morioka, Naoya; Hiraoka, Koichi

2018-03-01

We investigated the magnetization, M, and specific heat, C, of ThSi2-type PrGe2-δ. A polycrystalline sample of PrGe2-δ was prepared by arc-melting. Magnetization divided by magnetic field, M / B, increased sharply and C showed a clear jump at the Curie temperature, TC, of 14.6 K; these results indicate that PrGe2-δ ordered ferromagnetically. The magnetic entropy at TC reached R ln 3, indicating a quasi-triplet crystalline electric field (CEF) ground state. The maximum value of magnetic entropy change was 11.5 J/K kg with a field change of 7 T, which is comparable to those of other right rare-earth based magnetocaloric materials. This large magnetic entropy change was attributed to the quasi-triplet ground state of the CEF.

A framework of quality improvement interventions to implement evidence-based practices for pressure ulcer prevention.

PubMed

Padula, William V; Mishra, Manish K; Makic, Mary Beth F; Valuck, Robert J

2014-06-01

To enhance the learner's competence with knowledge about a framework of quality improvement (QI) interventions to implement evidence-based practices for pressure ulcer (PrU) prevention. This continuing education activity is intended for physicians and nurses with an interest in skin and wound care. After participating in this educational activity, the participant should be better able to:1. Summarize the process of creating and initiating the best-practice framework of QI for PrU prevention.2. Identify the domains and QI interventions for the best-practice framework of QI for PrU prevention. Pressure ulcer (PrU) prevention is a priority issue in US hospitals. The National Pressure Ulcer Advisory Panel endorses an evidence-based practice (EBP) protocol to help prevent PrUs. Effective implementation of EBPs requires systematic change of existing care units. Quality improvement interventions offer a mechanism of change to existing structures in order to effectively implement EBPs for PrU prevention. The best-practice framework developed by Nelson et al is a useful model of quality improvement interventions that targets process improvement in 4 domains: leadership, staff, information and information technology, and performance and improvement. At 2 academic medical centers, the best-practice framework was shown to physicians, nurses, and health services researchers. Their insight was used to modify the best-practice framework as a reference tool for quality improvement interventions in PrU prevention. The revised framework includes 25 elements across 4 domains. Many of these elements support EBPs for PrU prevention, such as updates in PrU staging and risk assessment. The best-practice framework offers a reference point to initiating a bundle of quality improvement interventions in support of EBPs. Hospitals and clinicians tasked with quality improvement efforts can use this framework to problem-solve PrU prevention and other critical issues.

Recent advances in photorefractivity of poly(4-diphenylaminostyrene) composites: Wavelength dependence and dynamic holographic images

NASA Astrophysics Data System (ADS)

Tsujimura, Sho; Kinashi, Kenji; Sakai, Wataru; Tsutsumi, Naoto

2014-08-01

To expand upon our previous report [Appl. Phys. Express 5, 064101 (2012) 064101], we provide here the modified poly(4-diphenylaminostyrene) (PDAS)-based photorefractive (PR) device on the basis of wavelength dependency, and demonstrate dynamic holographic images by using the PDAS-based PR device under the obtained appropriate conditions. The PR devices containing the triphenylamine unit have potential application to dynamic holographic images, which will be useful for real-time holographic displays.

Rational design of orally-active, pyrrolidine-based progesterone receptor partial agonists

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Scott K.; Washburn, David G.; Frazee, James S.

2010-09-03

Using the X-ray crystal structure of an amide-based progesterone receptor (PR) partial agonist bound to the PR ligand binding domain, a novel PR partial agonist class containing a pyrrolidine ring was designed. Members of this class of N-alkylpyrrolidines demonstrate potent and highly selective partial agonism of the progesterone receptor, and one of these analogs was shown to be efficacious upon oral dosing in the OVX rat model of estrogen opposition.

Binding of Single Walled Carbon Nanotube to WT and Mutant HIV-1 Proteases: Analysis of Flap Dynamics and Binding Mechanism

PubMed Central

Meher, Biswa Ranjan; Wang, Yixuan

2012-01-01

Most of the currently treated HIV-1 protease (HIV-PR) inhibitors have been prone to suffer from the mutations associated drug resistance. Therefore, it is necessary to search for potent alternatives against the drug resistance. In the current study we have tested the single-walled carbon nanotube (SWCNT) as an inhibitor in wild type (WT) as well as in three primary mutants (I50VPR, V82APR and I84VPR) of the HIV-1-PR through docking the SWCNT in the active site region, and then performed all-atom MD simulations for the complexes. The conformational dynamics of HIV-PR with a 20 ns trajectory reveals that the SWCNT can effectively bind to the HIV-1-PR active site and regulate the flap dynamics such as maintaining the flap-flap closed. To gain an insight into the binding affinity, we also performed the MM-PBSA based binding free energy calculations for the four HIV-PR/SWCNT complexes. It was observed that, although the binding between the SWCNT and the HIV-PR decreases due to the mutations, the SWCNTs bind to the HIV-PRs 3–5 folds stronger than the most potent HIV-1-PR inhibitor, TMC114. Remarkably, the significant interactions with binding energy higher than 1 kcal/mol focus on the flap and active regions, which favors closing flap-flap and deactivating the active residues of the HIV-PR. The flap dynamics and binding strength information for HIV-PR and SWCNTs can help design SWCNT-based HIV-1-PR inhibitors. PMID:23142620

“Support Your Client at the Space That They're in”: HIV Pre-Exposure Prophylaxis (PrEP) Prescribers' Perspectives on PrEP-Related Risk Compensation

PubMed Central

Magnus, Manya; Mayer, Kenneth H.; Krakower, Douglas S.; Eldahan, Adam I.; Hawkins, Lauren A. Gaston; Underhill, Kristen; Hansen, Nathan B.; Kershaw, Trace S.; Betancourt, Joseph R.; Dovidio, John F.

2017-01-01

Abstract Despite the demonstrated effectiveness of HIV pre-exposure prophylaxis (PrEP) and evidence that most PrEP users do not engage in risk compensation (i.e., increased risk behavior due to a perceived decrease in HIV susceptibility), some healthcare providers report patient risk compensation to be a deterrent to prescribing PrEP. Overcoming this barrier is essential to supporting PrEP access and uptake among people at risk for HIV. To inform such efforts, this qualitative study explored PrEP-related risk compensation attitudes among providers with firsthand experience prescribing PrEP. US-based PrEP providers (n = 18), most of whom were HIV specialists, were recruited through direct outreach and referral from colleagues and other participants. Individual 90-min semistructured interviews were conducted by phone or in person from September 2014 through February 2015, transcribed, and thematically analyzed. Three attitudinal themes emerged: (1) providers' role is to support patients in making informed decisions, (2) risk behavior while taking PrEP does not fully offset PrEP's protective benefit (i.e., PrEP confers net protection, even with added behavioral risk), and (3) PrEP-related risk compensation is unduly stigmatized within and beyond the healthcare community. Participants were critical of other healthcare providers' negative judgment of patients and reluctance to prescribe PrEP due to anticipated risk compensation. Several providers also acknowledged an evolution in their thinking from initial ambivalence toward greater acceptance of PrEP and PrEP-related behavior change. PrEP providers' insights about risk compensation may help to address unsubstantiated concerns about PrEP-related risk compensation and challenge the acceptability of withholding PrEP on these grounds. PMID:28414261

Fragment-Based Protein-Protein Interaction Antagonists of a Viral Dimeric Protease.

PubMed

Gable, Jonathan E; Lee, Gregory M; Acker, Timothy M; Hulce, Kaitlin R; Gonzalez, Eric R; Schweigler, Patrick; Melkko, Samu; Farady, Christopher J; Craik, Charles S

2016-04-19

Fragment-based drug discovery has shown promise as an approach for challenging targets such as protein-protein interfaces. We developed and applied an activity-based fragment screen against dimeric Kaposi's sarcoma-associated herpesvirus protease (KSHV Pr) using an optimized fluorogenic substrate. Dose-response determination was performed as a confirmation screen, and NMR spectroscopy was used to map fragment inhibitor binding to KSHV Pr. Kinetic assays demonstrated that several initial hits also inhibit human cytomegalovirus protease (HCMV Pr). Binding of these hits to HCMV Pr was also confirmed by NMR spectroscopy. Despite the use of a target-agnostic fragment library, more than 80 % of confirmed hits disrupted dimerization and bound to a previously reported pocket at the dimer interface of KSHV Pr, not to the active site. One class of fragments, an aminothiazole scaffold, was further explored using commercially available analogues. These compounds demonstrated greater than 100-fold improvement of inhibition. This study illustrates the power of fragment-based screening for these challenging enzymatic targets and provides an example of the potential druggability of pockets at protein-protein interfaces. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Framing HIV Pre-Exposure Prophylaxis (PrEP) for the General Public: How Inclusive Messaging May Prevent Prejudice from Diminishing Public Support.

PubMed

Calabrese, Sarah K; Underhill, Kristen; Earnshaw, Valerie A; Hansen, Nathan B; Kershaw, Trace S; Magnus, Manya; Krakower, Douglas S; Mayer, Kenneth H; Betancourt, Joseph R; Dovidio, John F

2016-07-01

Strategic framing of public messages about HIV pre-exposure prophylaxis (PrEP) may influence public support for policies and programs affecting access. This survey study examined how public attitudes toward PrEP differed based on the social group PrEP was described as benefiting ("beneficiary") and the moderating effect of prejudice. Members of the general public (n = 154) recruited online were randomly assigned to three beneficiary conditions: general population, gay men, or Black gay men. All participants received identical PrEP background information before completing measures of PrEP attitudes (specifying beneficiary), racism, and heterosexism. Despite anticipating greater PrEP adherence among gay men and Black gay men and perceiving PrEP as especially beneficial to the latter, participants expressed lower support for policies/programs making PrEP affordable for these groups vs. the general population. This disparity in support was stronger among participants reporting greater prejudice. Inclusive framing of PrEP in public discourse may prevent prejudice from undermining implementation efforts.

Framing HIV Pre-Exposure Prophylaxis (PrEP) for the General Public: How Inclusive Messaging May Prevent Prejudice from Diminishing Public Support

PubMed Central

Calabrese, Sarah K.; Underhill, Kristen; Earnshaw, Valerie A.; Hansen, Nathan B.; Kershaw, Trace S.; Magnus, Manya; Krakower, Douglas S.; Mayer, Kenneth H.; Betancourt, Joseph R.; Dovidio, John F.

2016-01-01

Strategic framing of public messages about HIV pre-exposure prophylaxis (PrEP) may influence public support for policies and programs affecting access. This survey study examined how public attitudes toward PrEP differed based on the social group PrEP was described as benefiting (“beneficiary”) and the moderating effect of prejudice. Members of the general public (n = 154) recruited online were randomly assigned to three beneficiary conditions: general population, gay men, or Black gay men. All participants received identical PrEP background information before completing measures of PrEP attitudes (specifying beneficiary), racism, and heterosexism. Despite anticipating greater PrEP adherence among gay men and Black gay men and perceiving PrEP as especially beneficial to the latter, participants expressed lower support for policies/programs making PrEP affordable for these groups vs. the general population. This disparity in support was stronger among participants reporting greater prejudice. Inclusive framing of PrEP in public discourse may prevent prejudice from undermining implementation efforts. PMID:26891840

The use of synthetic bedding in children. Do strategies of change influence associations with asthma?

PubMed

Behrens, Thomas; Maziak, Wasim; Weiland, Stephan K; Siebert, Edith; Rzehak, Peter; Keil, Ulrich

2005-04-01

Epidemiological data suggest in contrast to clinical recommendations a negative effect of synthetic bedding on asthma and respiratory symptoms. To assess the effects of bedding filled with synthetic material on the risk of asthma and respiratory symptoms in 6- to 7-year-old children, taking into account allergy-related change of bedding material. We analyzed data from the ISAAC Phase III cross-sectional survey (1999/2000) in Münster, Germany. Data were collected by parental report from representative school-based samples of 6- to 7-year old children (n = 3,529). We calculated prevalence ratios with 95% confidence intervals for the association between respiratory symptoms suggestive of asthma and synthetic pillows and blankets and adjusting for potential confounders. In the preliminary analyses, synthetic pillows and synthetic blankets were positively associated with the studied respiratory outcomes. For example, a high number of wheezing attacks was positively associated with synthetic pillows (PR = 4.44; 95% CI 2.84-6.94) and synthetic blankets (PR = 3.80; 95% CI 2.48-5.82). However, in the restricted analysis, excluding participants reporting allergy-related change of bedding (pillows n = 440; blankets n = 437), the positive associations disappeared for all studied outcomes. Our findings suggest that allergy-related choice of bedding is an important factor in the assessment of the relation between synthetic bedding and asthma symptoms. Ignoring those changes can lead to false-positive risk estimates. Prospective studies that allow to disentangle the temporal sequence of disease, exposure, and change of bedding should help to further clarify this issue.

The cost-effectiveness of HIV pre-exposure prophylaxis in men who have sex with men and transgender women at high risk of HIV infection in Brazil.

PubMed

Luz, Paula M; Osher, Benjamin; Grinsztejn, Beatriz; Maclean, Rachel L; Losina, Elena; Stern, Madeline E; Struchiner, Claudio J; Parker, Robert A; Freedberg, Kenneth A; Mesquita, Fabio; Walensky, Rochelle P; Veloso, Valdilea G; Paltiel, A David

2018-03-01

Men who have sex with men (MSM) and transgender women (TGW) in Brazil experience high rates of HIV infection. We examined the clinical and economic outcomes of implementing a pre-exposure prophylaxis (PrEP) programme in these populations. We used the Cost-Effectiveness of Preventing AIDS Complications (CEPAC)-International model of HIV prevention and treatment to evaluate two strategies: the current standard of care (SOC) in Brazil, including universal ART access (No PrEP strategy); and the current SOC plus daily tenofovir/emtracitabine PrEP (PrEP strategy) until age 50. Mean age (31 years, SD 8.4 years), age-stratified annual HIV incidence (age ≤ 40 years: 4.3/100 PY; age > 40 years: 1.0/100 PY), PrEP effectiveness (43% HIV incidence reduction) and PrEP drug costs ($23/month) were from Brazil-based sources. The analysis focused on direct medical costs of HIV care. We measured the comparative value of PrEP in 2015 United States dollars (USD) per year of life saved (YLS). Willingness-to-pay threshold was based on Brazil's annual per capita gross domestic product (GDP; 2015: $8540 USD). Lifetime HIV infection risk among high-risk MSM and TGW was 50.5% with No PrEP and decreased to 40.1% with PrEP. PrEP increased per-person undiscounted (discounted) life expectancy from 36.8 (20.7) years to 41.0 (22.4) years and lifetime discounted HIV-related medical costs from $4100 to $8420, which led to an incremental cost-effectiveness ratio (ICER) of $2530/YLS. PrEP remained cost-effective (<1x GDP) under plausible variation in key parameters, including PrEP effectiveness and cost, initial cohort age and HIV testing frequency on/off PrEP. Daily tenofovir/emtracitabine PrEP among MSM and TGW at high risk of HIV infection in Brazil would increase life expectancy and be highly cost-effective. © 2018 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

Small Molecule Regulation of Protein Conformation by Binding in the Flap of HIV Protease

PubMed Central

Tiefenbrunn, Theresa; Forli, Stefano; Baksh, Michael M.; Chang, Max W.; Happer, Meaghan; Lin, Ying-Chuan; Perryman, Alexander L.; Rhee, Jin-Kyu; Torbett, Bruce E.; Olson, Arthur J.; Elder, John H.; Finn, M. G.; Stout, C. David

2013-01-01

The fragment indole-6-carboxylic acid (1F1), previously identified as a flap site binder in a fragment-based screen against HIV protease (PR), has been co-crystallized with pepstatin-inhibited PR and with apo-PR. Another fragment, 3-indolepropionic acid (1F1-N), predicted by AutoDock calculations and confirmed in a novel ‘inhibition of nucleation’ crystallization assay, exploits the same interactions in the flap site in two crystal structures. Both 1F1 and 1F1-N bind to the closed form of apo-PR and to pepstatin:PR. In solution, 1F1 and 1F1-N raise the Tm of apo-PR by 3.5–5 °C as assayed by differential scanning fluorimetry (DSF), and show equivalent low-micromolar binding constants to both apo-PR and pepstatin:PR, assayed by backscattering interferometry (BSI). The observed signal intensities in BSI are greater for each fragment upon binding to apo-PR than to pepstatin-bound PR, consistent with greater conformational change in the former binding event. Together, these data indicate that fragment binding in the flap site favors a closed conformation of HIV PR. PMID:23540839

Energy transfer and radiative recombination processes in (Gd, Lu)3Ga3Al2O12:Pr3+ scintillators

NASA Astrophysics Data System (ADS)

Wu, Yuntao; Ren, Guohao

2013-10-01

(GdxLu3-x)Ga3Al2O12:0.3 at.%Pr (x = 0.025, 0.05, 0.1, 0.2, 0.4, 0.6) (GLGAG:Pr) polycrystalline powders are prepared by solid-state reaction method. To better understand the luminescence mechanism, the optical diffuse reflectance, photoluminescence emission and excitation, X-ray excited luminescence spectra and decay kinetics of GLGAG:Pr were investigated in detailed, allowing the determination of energy transfer from 5d state of Pr3+ to 4f state of Gd3+, and the non-radiative relaxation from 5d to 4f state of Pr3+. Besides, the former process plays more negative role in the emission quenching of GLGAG:Pr than later one. Pr3+ ion is regarded as an ineffective activation ion in Gd-based multicomponent aluminate garnets. In addition, the wavelength-resolved thermoluminescence spectra of GLGAG:Pr were studied after UV and X-ray irradiation. It is revealed that the localized recombination processes from electron traps to lower lying 4f levels of Pr3+ occurs without populating the higher 5d levels of Pr3+.

Sensitive spectrofluorometry of cellular prion protein based on the on-off interaction between fluorescent dye-labelled aptamers and multi-walled carbon nanotubes.

PubMed

Zhan, Lei; Peng, Li; Yu, Yan; Zhen, Shu Jun; Huang, Cheng Zhi

2012-11-07

The very simple and general spectrofluorometry of cellular prion protein (PrP(C)) is reported in this contribution based on the on-off noncovalent interaction of fluorescent dye-labelled PrP(C) DNA aptamers with multi-walled carbon nanotubes (MWCNTs). Due to the π-π stacking interaction between the DNA bases of the aptamer and the carbon nanotubes, the fluorescent dye and the MWCNTs are brought into close proximity, which leads to fluorescence quenching with a ratio of up to 87%. However, further addition of PrP(C), which disturbs the π-π interaction owing to the strong and specific binding of the aptamer to PrP(C), driving the aptamer away from the surface of the MWCNTs, restored the quenched fluorescence. This recovered fluorescence intensity was found to be in linear proportion to the PrP(C) concentration in the range of 8.2 to 81.7 nM, which builds the basis of the spectrofluorometry of the cellular prion protein.

Progesterone suppresses the invasion and migration of breast cancer cells irrespective of their progesterone receptor status - a short report.

PubMed

Godbole, Mukul; Tiwary, Kanishka; Badwe, Rajendra; Gupta, Sudeep; Dutt, Amit

2017-08-01

Pre-operative progesterone treatment of breast cancer has been shown to confer survival benefits to patients independent of their progesterone receptor (PR) status. The underlying mechanism and the question whether such an effect can also be observed in PR negative breast cancer cells remain to be resolved. We performed proteome profiling of PR-positive and PR-negative breast cancer cells in response to progesterone using a phospho-kinase array platform. Western blotting was used to validate the results. Cell-based phenotypic assays were conducted using PR-positive and PR-negative breast cancer cells to assess the effect of progesterone. We found that progesterone induces de-phosphorylation of 12 out of 43 kinases tested, which are mostly involved in cellular invasion and migration regulation. Consistent with this observation, we found through cell-based phenotypic assays that progesterone inhibits the invasion and migration of breast cancer cells independent of their PR status. Our results indicate that progesterone can inhibit breast cancer cell invasion and migration mediated by the de-phosphorylation of kinases. This inhibition appears to be independent of the PR status of the breast cancer cells. In a broader context, our study may provide a basis for an association between progesterone treatment and recurrence reduction in breast cancer patients, thereby providing a lead for modelling a randomized in vitro study.

Relationship between microstructural and magnetic properties of PrCo-based films prepared by the vacuum evaporation method

NASA Astrophysics Data System (ADS)

Fersi, R.; Bouzidi, W.; Bezergheanu, A.; Cizmas, C. B.; Bessais, L.; Mliki, N.

2018-04-01

In this work, Ce2Ni7 type structural PrCo-based films were deposited on Si(1 0 0) substrate by ultra-high (UHV) vacuum evaporation process. The structural and magnetic properties of these films have been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), vibrating sample magnetometer (VSM) and magnetic force microscopy (MFM) techniques. Two effects on structural and magnetic properties of PrCo films have been investigated: the effect of the annealing temperature (Ta) and the effect of the variation of the magnetic X-layer thickness. The as deposited PrCo films have a magnetic coercivity (Hc) of about 40-100 Oe. But after annealing at 600 °C, Hc has increased hight about 9.5 kOe for PrCo(X = 20 nm) and 10.2 kOe for PrCo(X = 50 nm) were observed. The magnetic properties were affected by the thickness due to the morphology, also the relationship between the intergrain exchange coupling (IEC), the size and quantity of the PrCo grains. The hight extrinsic properties of Hc = 10.2 kOe, maximum energy product (BH)max of 5.12 MGOe and remanence ratio Mr /Ms = 0.53 are reported for the PrCo(X = 50 nm) films. These properties are highly desirable for extremely high-density magnetic recording media applications.

Les conjonctivites néonatales dans le canton de Glidji au Sud du Togo: une étude transversale à propos de 159 nouveau-nés

PubMed Central

Kokou, Vonor; Nidain, Maneh; Kassoula, Nononsaa Batomguela; Kwassi, Fiaty- Amenouvor; Meba, Banla; Patrice, Balo Komi

2016-01-01

Introduction Le but de l’étude était décrire les aspects épidémiologiques des conjonctivites néonatales dans le canton de Glidji au Sud du Togo. Methodes Nous avons mené une étude transversale dans les 4 Unités Sanitaires Périphériques du canton de Glidji du 19 Mars au 13 Mai 2009 soit 8 semaines. Tous les nouveau-nés ont été inclus et la conjonctivite néonatale était définie par la présence chez un nouveau-né d'au moins deux des signes suivants: hyperhémie conjonctivale, œdème palpébral, chémosis, sécrétions purulentes, larmoiement. Les paramètres étudiés étaient l’âge, le sexe, les facteurs de risque, les antécédents, la présence ou non de conjonctivite, les germes en causes et l’évolution sous traitement. Resultats Sur la période, 159 nouveau-nés ont été examinés. L’âge moyen était de 10,9 jours avec des extrêmes de 0 à 28 jours. Il y avait 80 garçons pour 79 filles soit un sex-ratio de 1,01. Sur les 159 nouveau-nés, 7 cas de conjonctivite ont été diagnostiqués soit une prévalence de 4,4%. Les facteurs de risque identifiés étaient l'accouchement par voie basse et la présence d'IST chez la mère pendant la grossesse. Sur les 7 cas de conjonctivite, l'examen cytobactériologique a permis d'isoler le staphylococcus aureus dans 2 cas. L’évolution des cas de conjonctivite sous traitement était favorable avec régression des signes dès le 3è jour. Conclusion Les conjonctivites néonatales avaient une prévalence de 4,4% dans le canton de Glidji au sud du Togo et le staphylocoque doré était le germe en cause. Leur prévention passe par un bon suivi lors de la consultation prénatale et l'instillation de collyre antibiotique à la naissance PMID:27642383

Pattern recognition and expert image analysis systems in biomedical image processing (Invited Paper)

NASA Astrophysics Data System (ADS)

Oosterlinck, A.; Suetens, P.; Wu, Q.; Baird, M.; F. M., C.

1987-09-01

This paper gives an overview of pattern recoanition techniques (P.R.) used in biomedical image processing and problems related to the different P.R. solutions. Also the use of knowledge based systems to overcome P.R. difficulties, is described. This is illustrated by a common example ofabiomedical image processing application.

PaPrBaG: A machine learning approach for the detection of novel pathogens from NGS data

NASA Astrophysics Data System (ADS)

Deneke, Carlus; Rentzsch, Robert; Renard, Bernhard Y.

2017-01-01

The reliable detection of novel bacterial pathogens from next-generation sequencing data is a key challenge for microbial diagnostics. Current computational tools usually rely on sequence similarity and often fail to detect novel species when closely related genomes are unavailable or missing from the reference database. Here we present the machine learning based approach PaPrBaG (Pathogenicity Prediction for Bacterial Genomes). PaPrBaG overcomes genetic divergence by training on a wide range of species with known pathogenicity phenotype. To that end we compiled a comprehensive list of pathogenic and non-pathogenic bacteria with human host, using various genome metadata in conjunction with a rule-based protocol. A detailed comparative study reveals that PaPrBaG has several advantages over sequence similarity approaches. Most importantly, it always provides a prediction whereas other approaches discard a large number of sequencing reads with low similarity to currently known reference genomes. Furthermore, PaPrBaG remains reliable even at very low genomic coverages. CombiningPaPrBaG with existing approaches further improves prediction results.

Towards valid 'serious non-fatal injury' indicators for international comparisons based on probability of admission estimates.

PubMed

Cryer, Colin; Miller, Ted R; Lyons, Ronan A; Macpherson, Alison K; Pérez, Katherine; Petridou, Eleni Th; Dessypris, Nick; Davie, Gabrielle S; Gulliver, Pauline J; Lauritsen, Jens; Boufous, Soufiane; Lawrence, Bruce; de Graaf, Brandon; Steiner, Claudia A

2017-02-01

Governments wish to compare their performance in preventing serious injury. International comparisons based on hospital inpatient records are typically contaminated by variations in health services utilisation. To reduce these effects, a serious injury case definition has been proposed based on diagnoses with a high probability of inpatient admission (PrA). The aim of this paper was to identify diagnoses with estimated high PrA for selected developed countries. The study population was injured persons of all ages who attended emergency department (ED) for their injury in regions of Canada, Denmark, Greece, Spain and the USA. International Classification of Diseases (ICD)-9 or ICD-10 4-digit/character injury diagnosis-specific ED attendance and inpatient admission counts were provided, based on a common protocol. Diagnosis-specific and region-specific PrAs with 95% CIs were calculated. The results confirmed that femoral fractures have high PrA across all countries studied. Strong evidence for high PrA also exists for fracture of base of skull with cerebral laceration and contusion; intracranial haemorrhage; open fracture of radius, ulna, tibia and fibula; pneumohaemothorax and injury to the liver and spleen. Slightly weaker evidence exists for cerebellar or brain stem laceration; closed fracture of the tibia and fibula; open and closed fracture of the ankle; haemothorax and injury to the heart and lung. Using a large study size, we identified injury diagnoses with high estimated PrAs. These diagnoses can be used as the basis for more valid international comparisons of life-threatening injury, based on hospital discharge data, for countries with well-developed healthcare and data collection systems. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations

NASA Astrophysics Data System (ADS)

Bolen, Steven M.; Chandrasekar, V.

2003-06-01

The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ≥ 0.5°/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

Preferences for Injectable PrEP Among Young U.S. Cisgender Men and Transgender Women and Men Who Have Sex with Men.

PubMed

Biello, Katie B; Hosek, Sybil; Drucker, Morgan T; Belzer, Marvin; Mimiaga, Matthew J; Marrow, Elliot; Coffey-Esquivel, Julia; Brothers, Jennifer; Mayer, Kenneth H

2017-09-19

Young men who have sex with men account for approximately 20% of incident HIV infections in the U.S. Antiretroviral pre-exposure prophylaxis (PrEP) administered as a daily pill has been shown to decrease HIV acquisition in at-risk individuals. New modalities for PrEP are being developed and tested, including injectable PrEP; however, acceptability of these emerging modalities has not yet been examined in youth. We conducted six focus groups with 36 young men and transgender men and women who have sex with men in Boston, Chicago, and Los Angeles in 2016 to assess interest in and preference for different PrEP modalities. Youth were purposively recruited based on diversity of age, race/ethnicity, and prior PrEP experience. Data were coded using content coding based on key domains of the interview guide, in particular around the central themes of interest in and barriers and facilitators to injectable PrEP use. Participants were knowledgeable about oral PrEP but suggested barriers to broader uptake, including stigma, marginalization, and access to information. While participants were split on preference for injectable versus oral PrEP, they agreed quarterly injections may be more manageable and better for those who have adherence difficulties and for those who engage in sex more frequently. Concerns specific to injectable PrEP included: severity/duration of side effects, pain, level of protection prior to next injection, distrust of medical system and injections, and cost. Understanding barriers to and preferences for diverse prevention modalities will allow for more HIV prevention options, improved products, and better interventions, thus allowing individuals to make informed HIV prevention choices.

Novel multiplex bead-based assay for detection of IDH1 and IDH2 mutations in myeloid malignancies.

PubMed

Shivarov, Velizar; Ivanova, Milena; Hadjiev, Evgueniy; Naumova, Elissaveta

2013-01-01

Isocitrate dehydrogenase 1 and 2 (IDH) mutations are frequently found in various cancer types such as gliomas, chondrosarcomas and myeloid malignancies. Their molecular detection has recently gained wide recognition in the diagnosis and prognosis of these neoplasms. For that purpose various molecular approaches have been used but a universally accepted method is still lacking. In this study we aimed to develop a novel bead-based liquid assay using Locked nucleic acids (LNA)-modified oligonucleotide probes for multiplexed detection of the most frequent IDH1 (p.R132C, p.R132G, p.R132H, p.R132L, p.R132S) and IDH2 (p.R140Q, p.R172K) mutations. The method includes four steps: 1) PCR amplification of the targeted fragments with biotinylated primers; 2) Direct hybridization to barcoded microbeads with specific LNA-modified oligonucleotide probes; 3) Incubation with phycoerythrin coupled streptavidin; 4) Acquisition of fluorescent intensities of each set of beads on a flow platform (LuminexCorp., USA). We tested the performance of the assay on both artificial plasmid constructs and on clinical samples from 114 patients with known or suspected myeloid malignancies. The method appeared to be superior to direct sequencing having a much higher sensitivity of 2.5% mutant alleles. Applying this method to patients' samples we identified a total of 9 mutations (one IDH1 p.R132C, seven IDH2 p.R140Q and one IDH2 p.R172K). In conclusion, this method could be successfully implemented in the diagnostic work-up for various tumors known to harbor IDH1/2 mutations (e.g. myeloid malignancies, gliomas, etc.). International initiatives are needed to validate the different existing methods for detection of IDH1/2 mutations in clinical settings.

Comparative adoption of cone beam computed tomography and panoramic radiography machines across Australia.

PubMed

Zhang, A; Critchley, S; Monsour, P A

2016-12-01

The aim of the present study was to assess the current adoption of cone beam computed tomography (CBCT) and panoramic radiography (PR) machines across Australia. Information regarding registered CBCT and PR machines was obtained from radiation regulators across Australia. The number of X-ray machines was correlated with the population size, the number of dentists, and the gross state product (GSP) per capita, to determine the best fitting regression model(s). In 2014, there were 232 CBCT and 1681 PR machines registered in Australia. Based on absolute counts, Queensland had the largest number of CBCT and PR machines whereas the Northern Territory had the smallest number. However, when based on accessibility in terms of the population size and the number of dentists, the Australian Capital Territory had the most CBCT machines and Western Australia had the most PR machines. The number of X-ray machines correlated strongly with both the population size and the number of dentists, but not with the GSP per capita. In 2014, the ratio of PR to CBCT machines was approximately 7:1. Projected increases in either the population size or the number of dentists could positively impact on the adoption of PR and CBCT machines in Australia. © 2016 Australian Dental Association.

Pr3 + -doped GeSx-based glasses for fiber amplifiers at 1.3 µm

NASA Astrophysics Data System (ADS)

Simons, D. R.; Faber, A. J.; de Waal, H.

1995-03-01

The photoluminescence properties of Pr3+ -doped GeS x -based glasses are studied and compared with those of other sulfide and fluoride glasses. The possibility of highly pump-power-efficient fiber amplifiers based on these GeSx-containing glasses in the telecommunications window at 1.3 mu m is discussed.

Prognostic Significance of Progesterone Receptor–Positive Tumor Cells Within Immunohistochemically Defined Luminal A Breast Cancer

PubMed Central

Prat, Aleix; Cheang, Maggie Chon U.; Martín, Miguel; Parker, Joel S.; Carrasco, Eva; Caballero, Rosalía; Tyldesley, Scott; Gelmon, Karen; Bernard, Philip S.; Nielsen, Torsten O.; Perou, Charles M.

2013-01-01

Purpose Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes. Patients and Methods Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) –positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance. Results Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) –positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa. Conclusion Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A tumors is HR positive/HER2 negative/Ki-67 less than 14%, and PR more than 20%. PMID:23233704

Recent revisions of phosphate rock reserves and resources: a critique

NASA Astrophysics Data System (ADS)

Edixhoven, J. D.; Gupta, J.; Savenije, H. H. G.

2014-12-01

Phosphate rock (PR) is a finite mineral indispensable for fertilizer production, while P (phosphorus) is a major pollutant if applied or discharged in excess, causing widespread eutrophication (Carpenter and Bennet, 2011). High-grade PR is obtained from deposits which took millions of years to form and which are gradually being depleted. Recently, global PR reserves as reported by the US Geological Survey (USGS) have increased from 16 000 Mt PR in 2010 to 65 000 Mt PR in 2011 and further to 67 000 Mt PR in 2014. The majority of this 4-fold increase is based on a 2010 report by the International Fertilizer Development Center (IFDC), which increased Moroccan reserves from 5700 Mt PR as reported by USGS, to 51 000 Mt PR, reported as upgraded ("beneficiated") concentrate. The report also increased global resources from 163 000 Mt PR reported in the literature in 1989 to 290 000 Mt PR. IFDC used a simplified resource terminology which does not use the underlying thresholds for reserves and resources used in the USGS classification. IFDC proposed that agreement should be reached on PR resource terminology which should be as simple as possible. The report has profoundly influenced the PR scarcity debate, shifting the emphasis from resource scarcity to the pollution angle of the phosphate problem. In view of the high dependence of food production on PR and the importance of data on PR reserves and resources for scientific analysis and policy making, data on PR deposits should be transparent, comparable, reliable, and credible. We analyze (i) how IFDC's simplified terminology compares to international best practice in resource classification and whether it is likely to yield data that meet these requirements, (ii) whether the difference in volume between raw PR ore and upgraded PR concentrate is sufficiently noted in the literature, and (iii) whether the IFDC report presents an accurate picture of PR reserves and resources. We conclude that, while there is a global development toward common criteria in resource reporting, IFDC's lack of clear thresholds for reserves and resources contravenes this and that the vagueness of its definitions for reserves and resources may allow deposits to be termed reserves or resources which could not be recognized as such under leading mineral resource classifications. The difference between PR ore and PR concentrate is barely noted in the literature, causing pervasive confusion and a significant degree of error in many assessments. Finally, we find that the report most likely presents an inflated picture of global reserves, in particular those of Morocco, where the aggregate resources of three of the four Moroccan/Western Saharan major PR deposits appear to have been simply converted to "reserves". Following the release of the IFDC report, various analysts have concluded or suggested that the available PR deposits or even the currently reported resources would likely last several thousands of years at current consumption rates. However, the data on which these statements were based do not appear to warrant such a conclusion. Further research is required as to the quantity of PR deposits and their viability for future extraction, using uniform and transparent classification terminology.

7 CFR 2902.20 - Fluid-filled transformers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 15 2011-01-01 2011-01-01 false Fluid-filled transformers. 2902.20 Section 2902.20... Items § 2902.20 Fluid-filled transformers. (a) Definition. (1) Synthetic ester-based fluid-filled transformers. Electric power transformers that are designed to utilize a synthetic ester-based dielectric (non...

7 CFR 2902.20 - Fluid-filled transformers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Fluid-filled transformers. 2902.20 Section 2902.20... Items § 2902.20 Fluid-filled transformers. (a) Definition. (1) Synthetic ester-based fluid-filled transformers. Electric power transformers that are designed to utilize a synthetic ester-based dielectric (non...

Low fraction of the 222K PrP variant in the protease-resistant moiety of PrPres in heterozygous scrapie positive goats.

PubMed

Mazza, Maria; Guglielmetti, Chiara; Ingravalle, Francesco; Brusadore, Sonia; Langeveld, Jan P M; Ekateriniadou, Loukia V; Andréoletti, Olivier; Casalone, Cristina; Acutis, Pier Luigi

2017-07-01

The presence of lysine (K) at codon 222 has been associated with resistance to classical scrapie in goats, but few scrapie cases have been identified in 222Q/K animals. To investigate the contribution of the 222K variant to PrPres formation in natural and experimental Q/K scrapie cases, we applied an immunoblotting method based on the use of two different monoclonal antibodies, F99/97.6.1 and SAF84, chosen for their different affinities to 222K and 222Q PrP variants. Our finding that PrPres seems to be formed nearly totally by the 222Q variant provides evidence that the 222K PrP variant confers resistance to conversion to PrPres formation and reinforces the view that this mutation has a protective role against classical scrapie in goats.

Low fraction of the 222K PrP variant in the protease-resistant moiety of PrPres in heterozygous scrapie positive goats

PubMed Central

Guglielmetti, Chiara; Ingravalle, Francesco; Brusadore, Sonia; Langeveld, Jan P. M.; Ekateriniadou, Loukia V.; Andréoletti, Olivier; Casalone, Cristina; Acutis, Pier Luigi

2017-01-01

The presence of lysine (K) at codon 222 has been associated with resistance to classical scrapie in goats, but few scrapie cases have been identified in 222Q/K animals. To investigate the contribution of the 222K variant to PrPres formation in natural and experimental Q/K scrapie cases, we applied an immunoblotting method based on the use of two different monoclonal antibodies, F99/97.6.1 and SAF84, chosen for their different affinities to 222K and 222Q PrP variants. Our finding that PrPres seems to be formed nearly totally by the 222Q variant provides evidence that the 222K PrP variant confers resistance to conversion to PrPres formation and reinforces the view that this mutation has a protective role against classical scrapie in goats. PMID:28691895

Likelihood-based gene annotations for gap filling and quality assessment in genome-scale metabolic models

DOE PAGES

Benedict, Matthew N.; Mundy, Michael B.; Henry, Christopher S.; ...

2014-10-16

Genome-scale metabolic models provide a powerful means to harness information from genomes to deepen biological insights. With exponentially increasing sequencing capacity, there is an enormous need for automated reconstruction techniques that can provide more accurate models in a short time frame. Current methods for automated metabolic network reconstruction rely on gene and reaction annotations to build draft metabolic networks and algorithms to fill gaps in these networks. However, automated reconstruction is hampered by database inconsistencies, incorrect annotations, and gap filling largely without considering genomic information. Here we develop an approach for applying genomic information to predict alternative functions for genesmore » and estimate their likelihoods from sequence homology. We show that computed likelihood values were significantly higher for annotations found in manually curated metabolic networks than those that were not. We then apply these alternative functional predictions to estimate reaction likelihoods, which are used in a new gap filling approach called likelihood-based gap filling to predict more genomically consistent solutions. To validate the likelihood-based gap filling approach, we applied it to models where essential pathways were removed, finding that likelihood-based gap filling identified more biologically relevant solutions than parsimony-based gap filling approaches. We also demonstrate that models gap filled using likelihood-based gap filling provide greater coverage and genomic consistency with metabolic gene functions compared to parsimony-based approaches. Interestingly, despite these findings, we found that likelihoods did not significantly affect consistency of gap filled models with Biolog and knockout lethality data. This indicates that the phenotype data alone cannot necessarily be used to discriminate between alternative solutions for gap filling and therefore, that the use of other information is necessary to obtain a more accurate network. All described workflows are implemented as part of the DOE Systems Biology Knowledgebase (KBase) and are publicly available via API or command-line web interface.« less

Likelihood-Based Gene Annotations for Gap Filling and Quality Assessment in Genome-Scale Metabolic Models

PubMed Central

Benedict, Matthew N.; Mundy, Michael B.; Henry, Christopher S.; Chia, Nicholas; Price, Nathan D.

2014-01-01

Genome-scale metabolic models provide a powerful means to harness information from genomes to deepen biological insights. With exponentially increasing sequencing capacity, there is an enormous need for automated reconstruction techniques that can provide more accurate models in a short time frame. Current methods for automated metabolic network reconstruction rely on gene and reaction annotations to build draft metabolic networks and algorithms to fill gaps in these networks. However, automated reconstruction is hampered by database inconsistencies, incorrect annotations, and gap filling largely without considering genomic information. Here we develop an approach for applying genomic information to predict alternative functions for genes and estimate their likelihoods from sequence homology. We show that computed likelihood values were significantly higher for annotations found in manually curated metabolic networks than those that were not. We then apply these alternative functional predictions to estimate reaction likelihoods, which are used in a new gap filling approach called likelihood-based gap filling to predict more genomically consistent solutions. To validate the likelihood-based gap filling approach, we applied it to models where essential pathways were removed, finding that likelihood-based gap filling identified more biologically relevant solutions than parsimony-based gap filling approaches. We also demonstrate that models gap filled using likelihood-based gap filling provide greater coverage and genomic consistency with metabolic gene functions compared to parsimony-based approaches. Interestingly, despite these findings, we found that likelihoods did not significantly affect consistency of gap filled models with Biolog and knockout lethality data. This indicates that the phenotype data alone cannot necessarily be used to discriminate between alternative solutions for gap filling and therefore, that the use of other information is necessary to obtain a more accurate network. All described workflows are implemented as part of the DOE Systems Biology Knowledgebase (KBase) and are publicly available via API or command-line web interface. PMID:25329157

Occupational risk for Legionella infection among dental healthcare workers: meta-analysis in occupational epidemiology.

PubMed

Petti, Stefano; Vitali, Matteo

2017-07-13

The occupational risk for Legionella infection among dental healthcare workers (DHCWs) is conjectured because of the risk of routine inhalation of potentially contaminated aerosols produced by the dental instruments. Nevertheless, occupational epidemiology studies are contrasting. This meta-analysis assessed the level of scientific evidence regarding the relative occupational risk for Legionella infection among DHCWs. Literature search was performed without time and language restrictions, using broad data banks (PubMed, Scopus, Web of Science, GOOGLE Scholar) and generic keywords ('legionella' AND 'dent*'). Analytical cross-sectional studies comparing prevalence of high serum Legionella antibody levels in DHCWs and occupationally unexposed individuals were considered. The relative occupational risk was assessed through prevalence ratio (PR) with 95% CI. Between-study heterogeneity was assessed (Cochran's Q test) and was used to choose the meta-analytic method. Study quality (modified Newcastle-Ottawa Scale) and publication bias (Begg and Mazumdar's test, Egger and colleagues' test, trim and fill R 0 method) were assessed formally and considered for the sensitivity analysis. Sensitivity analysis to study inclusion, subgroup analyses (dental staff categories; publication year, before vs after 1998, ie, 5 years after the release by the Centers for Disease Control and Prevention of the infection control guidelines in dental healthcare setting) were performed. Seven studies were included (2232 DHCWs, 1172 occupationally unexposed individuals). No evidence of publication bias was detected. The pooled PR estimate was statistically non-significant at 95% level (1.7; 95% CI 0.8 to 3.2), study-quality adjustment did not change the PR considerably (PR, 1.5; 95% CI 0.5 to 4.1). PR was statistically significant before 1998 and no longer significant after 1998. Subgroup analysis according to DHCW categories was inconclusive. There is no scientific evidence that DHCWs are at high occupational risk. The differences between former and recent studies could be due to different characteristics of municipal water systems and the infection control guideline dissemination. © 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.

Effects of home-based pulmonary rehabilitation with a metronome-guided walking pace in chronic obstructive pulmonary disease.

PubMed

Lee, Sung-soon; Kim, Changhwan; Jin, Young-Soo; Oh, Yeon-Mok; Lee, Sang-Do; Yang, Yun Jun; Park, Yong Bum

2013-05-01

Despite documented efficacy and recommendations, pulmonary rehabilitation (PR) in chronic obstructive pulmonary disease (COPD) has been underutilized. Home-based PR was proposed as an alternative, but there were limited data. The adequate exercise intensity was also a crucial issue. The aim of this study was to investigate the effects of home-based PR with a metronome-guided walking pace on functional exercise capacity and health-related quality of life (HRQOL) in COPD. The subjects participated in a 12-week home-based PR program. Exercise intensity was initially determined by cardiopulmonary exercise test, and was readjusted (the interval of metronome beeps was reset) according to submaximal endurance test. Six-minute walk test, pulmonary function test, cardiopulmonary exercise test, and St. George's Respiratory Questionnaire (SGRQ) were done before and after the 12-week program, and at 6 months after completion of rehabilitation. Thirty-three patients participated in the program. Six-minute walking distance was significantly increased (48.8 m; P = 0.017) and the SGRQ score was also improved (-15; P < 0.001) over the six-month follow-up period after rehabilitation. There were no significant differences in pulmonary function and peak exercise parameters. We developed an effective home-based PR program with a metronome-guided walking pace for COPD patients. This rehabilitation program may improve functional exercise capacity and HRQOL.

Competing phases in a model of Pr-based cobaltites

NASA Astrophysics Data System (ADS)

Sotnikov, A.; Kuneš, J.

2017-12-01

Motivated by the physics of Pr-based cobaltites, we study the effect of the external magnetic field in the hole-doped two-band Hubbard model close to instabilities toward the excitonic condensation and ferromagnetic ordering. Using the dynamical mean-field theory we observe a field-driven suppression of the excitonic condensate. The onset of a magnetically ordered phase at the fixed chemical potential is accompanied by a sizable change of the electron density. This leads us to predict that Pr3 + abundance increases on the high-field side of the transition.

7 CFR 3201.20 - Fluid-filled transformers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 15 2012-01-01 2012-01-01 false Fluid-filled transformers. 3201.20 Section 3201.20... Designated Items § 3201.20 Fluid-filled transformers. (a) Definition. (1) Synthetic ester-based fluid-filled transformers. Electric power transformers that are designed to utilize a synthetic ester-based dielectric (non...

7 CFR 3201.20 - Fluid-filled transformers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 15 2014-01-01 2014-01-01 false Fluid-filled transformers. 3201.20 Section 3201.20... Designated Items § 3201.20 Fluid-filled transformers. (a) Definition—(1) Synthetic ester-based fluid-filled transformers. Electric power transformers that are designed to utilize a synthetic ester-based dielectric (non...

7 CFR 3201.20 - Fluid-filled transformers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 15 2013-01-01 2013-01-01 false Fluid-filled transformers. 3201.20 Section 3201.20... Designated Items § 3201.20 Fluid-filled transformers. (a) Definition—(1) Synthetic ester-based fluid-filled transformers. Electric power transformers that are designed to utilize a synthetic ester-based dielectric (non...

Prevalence of actual uptake and willingness to use pre-exposure prophylaxis to prevent HIV acquisition among men who have sex with men in Hong Kong, China

PubMed Central

Lau, Joseph T. F.; Fang, Yuan; Ip, Mary; Gross, Danielle L.

2018-01-01

Objectives This study was to investigate the prevalence of actual uptake of pre-exposure prophylaxis (PrEP), willingness to use daily oral PrEP under two cost scenarios, and potential issues related to PrEP use among men who have sex with men (MSM) with HIV negative/unknown sero-status in Hong Kong, China. Factors associated with the two measures of willingness were also investigated. Methods 403 eligible MSM completed the anonymous venue-based face-to-face interview/telephone interview. Results Only 1% had ever used PrEP. After being briefed about some facts of PrEP, the prevalence of willingness to use daily oral PrEP was 7.7% if they could purchase PrEP at private hospitals/clinics at HK$8,000 (US$1,032)/month (market rate) and 45.2% if free PrEP was provided by public hospitals/clinics in Hong Kong (free PrEP). After adjusted for significant background variables, significant factors of these two measures of willingness included: (1) number of correct responses to knowledge on PrEP, (2) perceived risk of HIV infection in the next six months, and (3) constructs of the Theory of Planned Behavior: positive and negative attitudes toward PrEP, perceived their significant others would support them take PrEP (perceived subjective norm), perceived number of local MSM who were willing to take PrEP (perceived descriptive norm), and confidence in using PrEP under the two scenarios (perceived behavioral control). Among all participants, 9.7% and 25.1% would start and discontinue using PrEP without consulting doctors; 26.0% would not take PrEP daily if it was provided for free, and 42.4% would not take up HIV testing every 3 months after using PrEP. Conclusion Different strategies should be considered for promoting PrEP at market rate and if free PrEP is made available. Future promotion should increase their knowledge about PrEP, modify their perceptions related to HIV and PrEP, and address some potential issues related to PrEP use. PMID:29432470

Sensitivity of Spaceborne and Ground Radar Comparison Results to Data Analysis Methods and Constraints

NASA Technical Reports Server (NTRS)

Morris, Kenneth R.; Schwaller, Mathew

2011-01-01

With the availability of active weather radar observations from space from the Precipitation Radar (PR) on board the Tropical Rainfall Measuring Mission (TR.MM) satellite, numerous studies have been performed comparing PR reflectivity and derived rain rates to similar observations from ground-based weather radars (GR). These studies have used a variety of algorithms to compute matching PR and GR volumes for comparison. Most studies have used a fixed 3-dimensional Cartesian grid centered on the ground radar, onto which the PR and GR data are interpolated using a proprietary approach and/or commonly available GR analysis software (e.g., SPRINT, REORDER). Other studies have focused on the intersection of the PR and GR viewing geometries either explicitly or using a hybrid of the fixed grid and PR/GR common fields of view. For the Dual-Frequency Precipitation Radar (DPR) of the upcoming Global Precipitation Measurement (GPM) mission, a prototype DPR/GR comparison algorithm based on similar TRMM PR data has been developed that defines the common volumes in terms of the geometric intersection of PR and GR rays, where smoothing of the PR and GR data are minimized and no interpolation is performed. The PR and GR volume-averaged reflectivity values of each sample volume are accompanied by descriptive metadata, for attributes including the variability and maximum of the reflectivity within the sample volume, and the fraction of range gates in the sample average having reflectivity values above an adjustable detection threshold (typically taken to be 18 dBZ for the PR). Sample volumes are further characterized by rain type (Stratiform or Convective), proximity to the melting layer, underlying surface (land/water/mixed), and the time difference between the PR and GR observations. The mean reflectivity differences between the PR and GR can differ between data sets produced by the different analysis methods; and for the GPM prototype, by the type of constraints and categorization applied to the data. In this paper, we will show results comparing the 3-D gridded analysis "black box" approach to the GPM prototype volume-matching approach, using matching TRMM PR and WSR-88D ground radar data. The affects of applying data constraints and data categorizations on the volume-matched data to the results will be shown, and explanations of the differences in terms of data and analysis algorithm characteristics will be presented. Implications of the differences to the determination of PR/DPR calibration differences and use of ground radar data to evaluate the PR and DPR attenuation correction algorithms will be discussed.

Moist air state above counterflow wet-cooling tower fill based on Merkel, generalised Merkel and Klimanek & Białecky models

NASA Astrophysics Data System (ADS)

Hyhlík, Tomáš

2017-09-01

The article deals with an evaluation of moist air state above counterflow wet-cooling tower fill. The results based on Klimanek & Białecky model are compared with results of Merkel model and generalised Merkel model. Based on the numerical simulation it is shown that temperature is predicted correctly by using generalised Merkel model in the case of saturated or super-saturated air above the fill, but the temperature is underpredicted in the case of unsaturated moist air above the fill. The classical Merkel model always under predicts temperature above the fill. The density of moist air above the fill, which is calculated using generalised Merkel model, is strongly over predicted in the case of unsaturated moist air above the fill.

Initial and long-term bond strengths of one-step self-etch adhesives with silane coupling agent to enamel-dentin-composite in combined situation.

PubMed

Mamanee, Teerapong; Takahashi, Masahiro; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

2015-01-01

This study evaluated the effect of adding silane coupling agent on initial and long-term bond strengths of one-step self-etch adhesives to enamel-dentin-composite in combined situation. Cervical cavities were prepared on extracted molars and filled with Clearfil AP-X. After water-storage for one-week, the filled teeth were sectioned in halves to expose enamel, dentin and composite surfaces and then enamel-dentin-composite surface was totally applied with one of adhesive treatments (Clearfil SE One, Clearfil SE One with Clearfil Porcelain Bond Activator, Beautibond Multi, Beautibond Multi with Beautibond Multi PR Plus and Scotchbond Universal). After designed period, micro-shear bond strengths (µSBSs) to each substrate were determined. For each period of water-storage, additive silane treatments significantly increased µSBS to composite (p<0.001). On the other hand, they significantly decreased µSBS to dentin (p<0.001), although did not have adverse effect on µSBS to enamel (p>0.05). Moreover, the stability of µSBS was depended on materials and substrates used.

Partially reduced graphene oxide-gold nanorods composite based bioelectrode of improved sensing performance.

PubMed

Nirala, Narsingh R; Abraham, Shiju; Kumar, Vinod; Pandey, Shobhit A; Yadav, Umakant; Srivastava, Monika; Srivastava, S K; Singh, Vidya Nand; Kayastha, Arvind M; Srivastava, Anchal; Saxena, Preeti S

2015-11-01

The present work proposes partially reduced graphene oxide-gold nanorods supported by chitosan (CH-prGO-AuNRs) as a potential bioelectrode material for enhanced glucose sensing. Developed on ITO substrate by immobilizing glucose oxidase on CH-prGO-AuNRs composite, these CH-prGO-AuNRs/ITO bioelectrodes demonstrate high sensitivity of 3.2 µA/(mg/dL)/cm(2) and linear range of 25-200 mg/dL with an ability to detect as low as 14.5 mg/dL. Further, these CH-prGO-AuNRs/ITO based electrodes attest synergistiacally enhanced sensing properties when compared to simple graphene oxide based CH-GO/ITO electrode. This is evident from one order higher electron transfer rate constant (Ks) value in case of CH-prGO-AuNRs modified electrode (12.4×10(-2) cm/s), in contrast to CH-GO/ITO electrode (6×10(-3) cm/s). Additionally, very low Km value [15.4 mg/dL(0.85 mM)] ensures better binding affinity of enzyme to substrate which is desirable for good biosensor stability and resistance to environmental interferences. Hence, with better loading capacity, kinetics and stability, the proposed CH-prGO-AuNRs composite shows tremendous potential to detect several bio-analytes in the coming future. Copyright © 2015 Elsevier B.V. All rights reserved.

Nitrogen-doped partially reduced graphene oxide rewritable nonvolatile memory.

PubMed

Seo, Sohyeon; Yoon, Yeoheung; Lee, Junghyun; Park, Younghun; Lee, Hyoyoung

2013-04-23

As memory materials, two-dimensional (2D) carbon materials such as graphene oxide (GO)-based materials have attracted attention due to a variety of advantageous attributes, including their solution-processability and their potential for highly scalable device fabrication for transistor-based memory and cross-bar memory arrays. In spite of this, the use of GO-based materials has been limited, primarily due to uncontrollable oxygen functional groups. To induce the stable memory effect by ionic charges of a negatively charged carboxylic acid group of partially reduced graphene oxide (PrGO), a positively charged pyridinium N that served as a counterion to the negatively charged carboxylic acid was carefully introduced on the PrGO framework. Partially reduced N-doped graphene oxide (PrGODMF) in dimethylformamide (DMF) behaved as a semiconducting nonvolatile memory material. Its optical energy band gap was 1.7-2.1 eV and contained a sp2 C═C framework with 45-50% oxygen-functionalized carbon density and 3% doped nitrogen atoms. In particular, rewritable nonvolatile memory characteristics were dependent on the proportion of pyridinum N, and as the proportion of pyridinium N atom decreased, the PrGODMF film lost memory behavior. Polarization of charged PrGODMF containing pyridinium N and carboxylic acid under an electric field produced N-doped PrGODMF memory effects that followed voltage-driven rewrite-read-erase-read processes.

Control of swine pseudorabies in China: Opportunities and limitations.

PubMed

Sun, Yuan; Luo, Yuzi; Wang, Chun-Hua; Yuan, Jin; Li, Na; Song, Kun; Qiu, Hua-Ji

2016-02-01

Pseudorabies (PR), also known as Aujeszky's disease (AD), is caused by pseudorabies virus (PRV) or called suid herpesvirus 1 (SuHV-1). It is an economically significant viral disease of pigs and other animals. Although the disease has been eradicated in commercial swine populations of some countries using gE-deleted vaccines and differentiating infected from vaccinated animals (DIVA) strategy, PR continues to be one of the most important diseases of pigs in many countries, particularly in regions with dense pig populations, including China. This article reviews the current situation of PR in China, including epidemiology, diagnostic assays, control strategies and challenges of the disease. PR has been endemic in most provinces of China largely due to the lack of appropriate compulsory vaccination campaigns of pigs, sufficient awareness and biosecurity measures, although gE-deleted vaccines based on the Bartha-K61 strain and regional DIVA-based eradication programs have been widely used in the past decades. Notably, since 2011, an emerging variant PRV with enhanced pathogenicity has become prevalent in vaccinated swine herds in many regions of China and the disease situation is worsening. Control and eventual eradication of PR remain a big challenge in China, and strengthened control measures based on updated DIVA strategy are urgently needed toward national eradication of PR. Copyright © 2015 Elsevier B.V. All rights reserved.

Speckle tracking and speckle content based composite strain imaging for solid and fluid filled lesions.

PubMed

Rabbi, Md Shifat-E; Hasan, Md Kamrul

2017-02-01

Strain imaging though for solid lesions provides an effective way for determining their pathologic condition by displaying the tissue stiffness contrast, for fluid filled lesions such an imaging is yet an open problem. In this paper, we propose a novel speckle content based strain imaging technique for visualization and classification of fluid filled lesions in elastography after automatic identification of the presence of fluid filled lesions. Speckle content based strain, defined as a function of speckle density based on the relationship between strain and speckle density, gives an indirect strain value for fluid filled lesions. To measure the speckle density of the fluid filled lesions, two new criteria based on oscillation count of the windowed radio frequency signal and local variance of the normalized B-mode image are used. An improved speckle tracking technique is also proposed for strain imaging of the solid lesions and background. A wavelet-based integration technique is then proposed for combining the strain images from these two techniques for visualizing both the solid and fluid filled lesions from a common framework. The final output of our algorithm is a high quality composite strain image which can effectively visualize both solid and fluid filled breast lesions in addition to the speckle content of the fluid filled lesions for their discrimination. The performance of our algorithm is evaluated using the in vivo patient data and compared with recently reported techniques. The results show that both the solid and fluid filled lesions can be better visualized using our technique and the fluid filled lesions can be classified with good accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating the Genetic Architecture of the PR Interval Using Clinical Phenotypes.

PubMed

Mosley, Jonathan D; Shoemaker, M Benjamin; Wells, Quinn S; Darbar, Dawood; Shaffer, Christian M; Edwards, Todd L; Bastarache, Lisa; McCarty, Catherine A; Thompson, Will; Chute, Christopher G; Jarvik, Gail P; Crosslin, David R; Larson, Eric B; Kullo, Iftikhar J; Pacheco, Jennifer A; Peissig, Peggy L; Brilliant, Murray H; Linneman, James G; Witte, John S; Denny, Josh C; Roden, Dan M

2017-04-01

One potential use for the PR interval is as a biomarker of disease risk. We hypothesized that quantifying the shared genetic architectures of the PR interval and a set of clinical phenotypes would identify genetic mechanisms contributing to PR variability and identify diseases associated with a genetic predictor of PR variability. We used ECG measurements from the ARIC study (Atherosclerosis Risk in Communities; n=6731 subjects) and 63 genetically modulated diseases from the eMERGE network (Electronic Medical Records and Genomics; n=12 978). We measured pairwise genetic correlations (rG) between PR phenotypes (PR interval, PR segment, P-wave duration) and each of the 63 phenotypes. The PR segment was genetically correlated with atrial fibrillation (rG=-0.88; P =0.0009). An analysis of metabolic phenotypes in ARIC also showed that the P wave was genetically correlated with waist circumference (rG=0.47; P =0.02). A genetically predicted PR interval phenotype based on 645 714 single-nucleotide polymorphisms was associated with atrial fibrillation (odds ratio=0.89 per SD change; 95% confidence interval, 0.83-0.95; P =0.0006). The differing pattern of associations among the PR phenotypes is consistent with analyses that show that the genetic correlation between the P wave and PR segment was not significantly different from 0 (rG=-0.03 [0.16]). The genetic architecture of the PR interval comprises modulators of atrial fibrillation risk and obesity. © 2017 American Heart Association, Inc.

Reproductive performance in a select sample of dairy herds.

PubMed

Ferguson, James D; Skidmore, Andrew

2013-02-01

Sixteen herds were selected from a pool of 64 herds nominated by consultants for participation in a national survey to demonstrate excellence in reproductive performance. For inclusion in the survey, herds had to have comprehensive records in a farm computer database or participate in a Dairy Herd Improvement Association record system and have superior reproductive performance as judged by the herd advisor. Herd managers were asked to fill out a questionnaire to describe their reproductive management practices and provide herd records for data analysis. Reproductive analysis was based on individual cow records for active and cull dairy cows that calved during the calendar year 2010. Breeding records by cow were used to calculate indices for insemination rate (IR), conception rate (CR), pregnancy rate (PR), and culling. Herds ranged in size from 262 to 6,126 lactating and dry cows, with a mean of 1,654 [standard deviation (SD) 1,494] cows. Mean days to first insemination (DFS) was 71.2d (SD 4.7d), and IR for first insemination was 86.9%. Mean days between inseminations were 33.4d (SD 3.1d), and 15.4% of insemination intervals were greater than 48 d (range: 7.2 to 21.5%). First-service conception rate was 44.4% (SD 4.8%) across all herds and ranged from 37.5 to 51.8%. Mean PR was 32.0% (SD 3.9%) with a range of 26.5 to 39.4%. Lactation cull rate was 32.2% (SD 12.4%) with a range from 13.6 to 58.1%. Compared with mean data and SD for herds in the Raleigh Dairy Herd Improvement Association system, mean indices for these herds ranked them in the 99 th percentile for IR (using heat detection rate as comparison), 99 th percentile for PR, the bottom 18.6 percentile for DFS, and around the 50th percentile for CR. This suggests that excellent herd reproductive performance was associated with reproductive management that resulted in high insemination rates combined with average CR. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Les expériences de victimisation, la santé mentale et le bien-être de jeunes trans au Québec

PubMed Central

Raymond, Guillaume; Blais, Martin; Bergeron, Félix-Antoine; Hébert, Martine

2016-01-01

Résumé Les normes traditionnelles de genre prescrivent l’adéquation de l’expression de la masculinité et de la féminité au sexe anatomique de naissance. Les personnes qui présentent des variations dans l’expression de genre sont sujettes à diverses formes de réactions sociales suggérant la réprobation (des regards désapprobateurs aux violences physiques) susceptibles d’influencer négativement leur santé mentale. Trente-sept (37) jeunes se décrivant comme trans ou en questionnement sur leur identité de genre ont été recrutés dans le cadre de l’enquête sur les Parcours Amoureux des Jeunes de minorités sexuelles du Québec. Leurs expériences de victimisation parentale et de victimisation basée sur la non-conformité de genre ainsi que des indicateurs de santé mentale (détresse psychologique, estime de soi) ont été mesurés. Afin de comparer les expériences de victimisation et l’état de santé mentale des jeunes trans, ils ont été appariés à 37 garçons et 37 filles cisgenres sur la base de leurs caractéristiques sociodémographiques. Des analyses de prévalence et un modèle acheminatoire ont été réalisés. Les résultats mettent en évidence que les jeunes trans sont plus susceptibles de présenter des scores cliniques de détresse psychologique et de faible estime d’eux-mêmes que leurs pairs cisgenres. La violence verbale parentale et la victimisation basée sur la non-conformité de genre influencent négativement l’estime de soi, ce qui en retour augmente la probabilité de vivre de la détresse psychologique. Les résultats appuient l’importance des interventions de soutien à la diversité sexuelle et de genre. PMID:26966849

Distinguishing hypothetical willingness from behavioral intentions to initiate HIV pre-exposure prophylaxis (PrEP): Findings from a large cohort of gay and bisexual men in the U.S.

PubMed

Rendina, H Jonathon; Whitfield, Thomas H F; Grov, Christian; Starks, Tyrel J; Parsons, Jeffrey T

2017-01-01

Much of the data on the acceptability of HIV Pre-Exposure Prophylaxis (PrEP) is based on willingness to take PrEP (i.e., hypothetical receptivity) rather than actual intentions (i.e., planned behavioral action) to do so. We sought to examine differences between hypothetical willingness and behavioral intentions to begin PrEP in a national sample of gay and bisexual men (GBM) across the U.S. We utilized data collected in 2015 to examine differences between those Unwilling (42.6% n = 375), Willing but not intending (41.4%, n = 365), and willing and Intending to take PrEP (15.9%, n = 140) in a multivariable, multinomial logistic regression. Men with less education had higher odds of Intending to take PrEP. Compared to men unsure about PrEP's efficacy, those who believed PrEP was at least 90% efficacious had higher odds of Intending to take PrEP. Those who saw themselves as appropriate candidates for PrEP had higher odds of Intending to take PrEP while those who saw themselves as inappropriate candidates for PrEP had lower odds of Intending to take PrEP in comparison to men unsure if they were appropriate candidates. Increased motivation for condom non-use because of perceived sexual pressure by partners was associated with higher odds of Intending to take PrEP. The groups did not differ by risk behavior nor recent STI diagnosis. Overall, the distinction between willingness and intentions to take PrEP was meaningful and may help explain disparities between PrEP acceptability and uptake. While much of the literature has focused on hypothetical willingness to take PrEP, these results highlight the importance of simultaneously assessing willingness and intentions when examining correspondence with uptake and developing interventions to increase PrEP uptake. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of bulk-fill base material on fracture strength of root-filled teeth restored with laminate resin composite restorations.

PubMed

Taha, N A; Maghaireh, G A; Ghannam, A S; Palamara, J E

2017-08-01

To evaluate the effect of using a bulk-fill flowable base material on fracture strength and fracture patterns of root-filled maxillary premolars with MOD preparations restored with laminate restorations. Fifty extracted maxillary premolars were selected for the study. Standardized MOD cavities with endodontic treatment were prepared for all teeth, except for intact control. The teeth were divided randomly into five groups (n=10); (Group 1) sound teeth, (Group 2) unrestored teeth; (Group 3) MOD cavities with Vitrebond base and resin-based composite (Ceram. X One Universal); (Group 4) MOD cavities with 2mm GIC base (Fuji IX GP) and resin-based composite (Ceram. X One Universal) open laminate, (Group 5) MOD cavities were restored with 4mm of bulk-fill flowable base material (SDR) and resin-based composite (Ceram. X One Universal). All teeth were thermocycled and subjected to a 45° ramped oblique load in a universal testing machine. Fracture load and fracture patterns were recorded. Data were analyzed using one-way ANOVA and Dunnett's T3 test. Restoration in general increased the fracture strength compared to unrestored teeth. The fracture strength of group 5 (bulk-fill) was significantly higher than the fracture strength of the GIC laminate groups and not significantly different from the intact teeth (355±112N, P=0.118). The type of failure was unfavorable for most of the groups, with the majority being mixed failures. The use of a bulk-fill flowable base material significantly increased the fracture strength of extracted root-filled teeth with MOD cavities; however it did not improve fracture patterns to more favorable ones. Investigating restorative techniques that may improve the longevity of root-filled premolar teeth restored with direct resin restorations. Copyright © 2017 Elsevier Ltd. All rights reserved.

HIV Care Providers' Intentions to Prescribe and Actual Prescription of Pre-Exposure Prophylaxis to At-Risk Adolescents and Adults.

PubMed

Mullins, Tanya L Kowalczyk; Zimet, Gregory; Lally, Michelle; Xu, Jiahong; Thornton, Sarah; Kahn, Jessica A

2017-12-01

Pre-exposure prophylaxis (PrEP) is indicated for use in US adults, and little is known about clinician intentions to prescribe and actual prescription of PrEP to adolescents younger than 18. Fifty-six clinicians who care for HIV-infected and at-risk youth completed an anonymous online survey in 2014. Primary outcomes were (1) intentions to prescribe PrEP to adolescents and adults in four risk categories [men who have sex with men (MSM), transgender women, heterosexuals with multiple partners of unknown HIV status, heterosexuals with HIV-infected partners]; and (2) actual prescription of PrEP to adolescents and adults in these risk groups. Independent variables included clinician characteristics, experience prescribing nonoccupational postexposure prophylaxis, familiarity with and knowledge of PrEP and PrEP guidance, attitudes toward PrEP, and facilitating factors for prescribing PrEP and incorporation of PrEP guidance into practice. Variables associated with intention to prescribe ("very likely to prescribe" vs. other responses) and actual prescription of PrEP stratified by age and risk category were identified in logistic regression models. Mean age was 45.9 years (standard deviation 10.7); 64% were physicians. More clinicians reported high intention to prescribe PrEP to adult versus adolescent MSM (p = 0.02) and transgender women (p = 0.001). Variables associated with intention to prescribe and prescription of PrEP differed by age and risk category. In adolescents, those variables included positive beliefs, higher number of facilitating factors, and fewer barriers to PrEP prescription. Designing strategies based on these findings that address both facilitating factors and barriers to PrEP prescription may improve PrEP uptake by at-risk youth.

Shouldering the Load: An Analysis of Gender-Based Differences in the Undergraduate PR Writing Classes and Advising Undergraduate PRSSA Chapters

ERIC Educational Resources Information Center

Waymer, Damion

2014-01-01

This study contributes to public relations (PR) literature and research because it finds and highlights discrepancies between male and female PR faculty concerning their involvement or lack thereof with designated labor-intensive teaching and service responsibilities. More specifically, this study finds that more females serve as faculty advisors…

Differences in uterine immunoexpression of PR, ERα and OTR when comparing prostaglandin- to progestagen-based protocols for ovine estrus synchronization.

PubMed

Ruiz-González, I; Sánchez, M A; García-Palencia, P; Sánchez, B; García-Fernández, R A; González-Bulnes, A; Flores, J M

2012-07-01

The aim of this work was to compare PR, ERα and OTR uterine expression between days 9 and 21 of pregnancy in ewes whose estrus had been synchronized with two different protocols. Sixty-four adult Manchega ewes were synchronized with either conventional progestagens (P) or prostaglandin analogues (PG), and mated. Uterine samples were obtained from pregnant animals (group P, n=24; group PG, n=25) on days 9 post coitus (pc), 13pc, 15pc, 17pc and 21pc. Immunohistochemical detection of progesterone receptor (PR), estrogen receptor-α (ERα) and oxytocin receptor (OTR) was assessed in different uterine cell compartments including luminal and glandular epithelium, stroma and myometrium. Interaction day × treatment was obtained when assessing PR expression in the caruncular stroma (P=0.027) and myometrium (P=0.000), as well as for ERα in the superficial stroma (P=0.05). Significant "day post coitus" effect was found regarding to PR (P<0.01, with the exception of the superficial stroma, deep stroma and myometrium), ERα (P<0.01), and OTR (P<0.05, except in the deep compartments). No significant "treatment" effect was found for PR, ERα or OTR protein immunoexpression. This study supports the implication of PR, ERα and OTR within days 9-21 of the ovine pregnancy. Moreover, different expression pattern of PR and ERα proteins has been found between treatments in various compartments studied. Collectively, these results indicate that PR, ERα and OTR expression during early pregnancy is similar between ewes treated with either progestagens or prostaglandin analogues-based protocols for estrus synchronization. Copyright © 2012 Elsevier B.V. All rights reserved.

From modeling to morals: imagining the future of HIV PREP in Lesotho.

PubMed

Kenworthy, Nora J; Bulled, Nicola

2013-08-01

Amidst growing global endorsements of new biomedical HIV prevention strategies, ARV-based pre-exposure prophylaxis (ARV PrEP) has garnered considerable attention as a potentially promising prevention strategy. Though it may offer more effective protection for certain at-risk groups than conventional prevention strategies (such as sexual partner reduction, condom use, and prevention of mother-to-child transmission), PrEP is more costly. PrEP requires more ongoing contact between individuals and providers, and a level of surveillance from the health system that is not necessary with other preventive measures. In this sense, it represents a new bio-technology for HIV prevention that poses particular challenges for worldwide implementation, given developing countries' struggling health systems and incomplete HIV treatment programs. Since the emergence of PrEP has stimulated ethical discussions premised on incomplete knowledge of efficacy and implementation, this paper explores the ethical parameters of a likely scenario for PrEP usage in a single, resource-poor country. We first develop a plausible model for PrEP deployment and utilization based on current PrEP research, while carefully considering the reigning institutional values of feasibility and effectiveness in global health approaches. Drawing on ethnographic research of HIV treatment and prevention approaches in Lesotho, we address ethical questions arising from this scenario of PrEP delivery. Lesotho presents a compelling and emblematic case study of PrEP's potential successes and pitfalls in a developing country, given the country's high HIV prevalence, struggles to achieve universal access to HIV treatment regimes, continued existence of stigma around the epidemic, and difficulties in addressing persistent social inequalities that fuel infections. © 2013 John Wiley & Sons Ltd.

Unexpected formal insertion of CO 2 into the C-Si bonds of a zinc compound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kemp, Richard A.; McGrew, Genette I.; Khatri, Pathik A.

Reaction of [κ 2-PR 2C(SiMe 3)Py] 2Zn (R = Ph, 2a; iPr, 2b) with CO 2 affords the products of formal insertion at the C–Si bond, [κ 2-PR 2CC(O)O(SiMe 3)Py] 2Zn (R = Ph, 3a; iPr, 3b). Insertion product 3b was structurally characterized. As a result, the reaction appears to be a stepwise insertion and rearrangement of CO 2 based on kinetic data.

Unexpected formal insertion of CO 2 into the C-Si bonds of a zinc compound

DOE PAGES

Kemp, Richard A.; McGrew, Genette I.; Khatri, Pathik A.; ...

2015-09-08

Reaction of [κ 2-PR 2C(SiMe 3)Py] 2Zn (R = Ph, 2a; iPr, 2b) with CO 2 affords the products of formal insertion at the C–Si bond, [κ 2-PR 2CC(O)O(SiMe 3)Py] 2Zn (R = Ph, 3a; iPr, 3b). Insertion product 3b was structurally characterized. As a result, the reaction appears to be a stepwise insertion and rearrangement of CO 2 based on kinetic data.

Echo spectroscopy of TLS of multiwell adiabatic potential for Pr3+ activator centers in Y2SiO5

NASA Astrophysics Data System (ADS)

Malyukin, Yuri V.; Borysov, R. S.; Zhmurin, P. N.; Lebedenko, A. N.; Grinyov, Boris V.; Znamenskii, N. I.; Manykin, Eduard A.; Orlov, Yu. V.; Petrenko, E. A.; Yukina, T. G.

2002-05-01

Based on the investigation of the temperature dependence of the two-pulse phonon echo amplitude on the 3H4 3Po resonant optical transition of the Pr3+ doped ions in the Y2SiO5 crystal, unusual for crystals, low-temperature mechanisms of Pr3+ spectral line broadening caused by the interaction of doped ions with TLS have been found. The constants characterizing the interaction of the doped Pr3+ ions with phonons and TLS have been determined.

Motives of Dutch men who have sex with men for daily and intermittent HIV pre-exposure prophylaxis usage and preferences for implementation: A qualitative study.

PubMed

Bil, Janneke P; van der Veldt, Wendy M; Prins, Maria; Stolte, Ineke G; Davidovich, Udi

2016-09-01

Although PrEP is not yet registered in Europe, including the Netherlands, its approval and implementation are expected in the near future. To inform future pre-exposure prophylaxis (PrEP) implementation, this study aimed to gain insight into motives and preferences for daily or intermittent PrEP use among Dutch HIV-negative men having sex with men (MSM).Between February and December 2013, semistructured interviews were conducted until data saturation was reached (N = 20). Interviews were analyzed using the Grounded Theory approach.Motives for (not) using daily PrEP were based on beliefs about PrEP efficacy and side effects, preferences for other prevention strategies, self-perceived HIV risk, self-perceived efficacy of PrEP adherence, beliefs about possible benefits (e.g., anxiety reduction, sex life improvement), and barriers of PrEP use (e.g., costs, monitoring procedures). The perceived benefits of intermittent versus daily PrEP use were the lower costs and side effects and the lower threshold to decision to start using intermittent PrEP. Barriers of intermittent PrEP versus daily PrEP use were the perceived need to plan their sex life and adhere to multiple prevention strategies. Although some perceived PrEP as a condom substitute, others were likely to combine PrEP and condoms for sexually transmitted infections (STI) prevention and increased HIV protection. Participants preferred PrEP service locations to have specialized knowledge of HIV, antiretroviral therapy, sexual behavior, STIs, patients' medical background, be easily approachable, be able to perform PrEP follow-up monitoring, and provide support.To maximize the public health impact of PrEP, ensuring high uptake among MSM at highest risk is important. Therefore, targeted information about PrEP efficacy and side effects need to be developed, barriers for accessing PrEP services should be minimized, and perceived self-efficacy to use PrEP should be addressed and improved. To prevent increases in STIs, condom use should be monitored and PrEP should be integrated into routine STI screening and counseling.

Motives of Dutch men who have sex with men for daily and intermittent HIV pre-exposure prophylaxis usage and preferences for implementation

PubMed Central

Bil, Janneke P.; van der Veldt, Wendy M.; Prins, Maria; Stolte, Ineke G.; Davidovich, Udi

2016-01-01

Abstract Although PrEP is not yet registered in Europe, including the Netherlands, its approval and implementation are expected in the near future. To inform future pre-exposure prophylaxis (PrEP) implementation, this study aimed to gain insight into motives and preferences for daily or intermittent PrEP use among Dutch HIV-negative men having sex with men (MSM). Between February and December 2013, semistructured interviews were conducted until data saturation was reached (N = 20). Interviews were analyzed using the Grounded Theory approach. Motives for (not) using daily PrEP were based on beliefs about PrEP efficacy and side effects, preferences for other prevention strategies, self-perceived HIV risk, self-perceived efficacy of PrEP adherence, beliefs about possible benefits (e.g., anxiety reduction, sex life improvement), and barriers of PrEP use (e.g., costs, monitoring procedures). The perceived benefits of intermittent versus daily PrEP use were the lower costs and side effects and the lower threshold to decision to start using intermittent PrEP. Barriers of intermittent PrEP versus daily PrEP use were the perceived need to plan their sex life and adhere to multiple prevention strategies. Although some perceived PrEP as a condom substitute, others were likely to combine PrEP and condoms for sexually transmitted infections (STI) prevention and increased HIV protection. Participants preferred PrEP service locations to have specialized knowledge of HIV, antiretroviral therapy, sexual behavior, STIs, patients’ medical background, be easily approachable, be able to perform PrEP follow-up monitoring, and provide support. To maximize the public health impact of PrEP, ensuring high uptake among MSM at highest risk is important. Therefore, targeted information about PrEP efficacy and side effects need to be developed, barriers for accessing PrEP services should be minimized, and perceived self-efficacy to use PrEP should be addressed and improved. To prevent increases in STIs, condom use should be monitored and PrEP should be integrated into routine STI screening and counseling. PMID:27684827

Defining Survivorship Trajectories Across Patients With Solid Tumors: An Evidence-Based Approach.

PubMed

Dood, Robert L; Zhao, Yang; Armbruster, Shannon D; Coleman, Robert L; Tworoger, Shelley; Sood, Anil K; Baggerly, Keith A

2018-06-02

Survivorship involves a multidisciplinary approach to surveillance and management of comorbidities and secondary cancers, overseen by oncologists, surgeons, and primary care physicians. Optimal timing and coordination of care, however, is unclear and often based on arbitrary 5-year cutoffs. To determine high- and low-risk periods for all tumor types that could define when survivorship care might best be overseen by oncologists and when to transition to primary care physicians. In this pan-cancer, longitudinal, observational study, excess mortality hazard, calculated as an annualized mortality risk above a baseline population, was plotted over time. The time this hazard took to stabilize defined a high-risk period. The percent morality elevation above age- and sex-matched controls in the latter low-risk period was reported as a mortality gap. The US population-based Surveillance, Epidemiology, and End Results database defined the cancer population, and the US Census life tables defined controls. Incident cases of patients with cancer were separated into tumor types based on International Classification of Diseases for Oncology definitions. Population-level data on incident cancer cases was compared with the general US population. Overall mortality and cause of death were reported on observed cancer cases. A total of 2 317 185 patients (median age, 63 years; 49.8% female) with 66 primary tumor types were evaluated. High-risk surveillance period durations ranged from less than 1 year (breast, prostate, lip, ocular, and parathyroid cancers) up to 19 years (unspecified gastrointestinal cancers). The annualized mortality gap, representing the excess mortality in the stable period, ranged from a median 0.26% to 9.33% excess annual mortality (thyroid and hypopharyngeal cancer populations, respectively). Cluster analysis produced 6 risk cluster groups: group 1, with median survival of 16.2 (5th to 95th percentile range [PR], 10.7-40.2) years and median high-risk period of 2.5 (PR, 0-5.0) years; group 2, 8.3 (PR, 5.1-23.3) and 2.5 (PR, 4.0-8.0) years; group 3, 2.8 (PR, 1.4-3.7) and 7.0 (PR, 6.0-11.1) years; group 4, 1.6 (PR, 1.5-1.8) and 6.0 (PR, 5.1-11.4) years; group 5, 0.8 (PR, 0.5-1.2) and 0.8 (PR, 0.5-1.2) years; and group 6, 0.5 (PR, 0.4-0.8) and 12.0 (PR, 9.3-12.9) years, respectively. Subanalyses of selected tumor types in these groups revealed that stratifying on stage and histologic type can change the risk cluster and guidance for care. These findings indicate that a standardized 5-year surveillance period is inadequate for some cancers while excessive for others. High-risk cancers require the most resources with the longest high-risk period, highest persistent baseline mortality risk, and longest period of primary cancer mortality, all arguing for longer follow-up with an oncologist in these cancers.

The Pr 2O 3/Si(0 0 1) interface studied by synchrotron radiation photo-electron spectroscopy

NASA Astrophysics Data System (ADS)

Schmeißer, D.; Müssig, H.-J.

2003-10-01

Pr 2O 3 is currently under consideration as a potential replacement for SiO 2 as the gate-dielectric material for sub-0.1 μm complementary metal-oxide-semiconductor (CMOS) technology. We studied the Pr 2O 3/Si(0 0 1) interface by a non-destructive depth profiling using synchrotron radiation photoelectron spectroscopy. Our data suggests that there is no silicide formation at the interface. Based on reported results, a chemical reactive interface exists, consisting of a mixed Si-Pr oxide such as (Pr 2O 3) x(SiO 2) 1- x, i.e. as a silicate phase with variable silicon content. This pseudo-binary alloy at the interface offers large flexibility toward successful integration of Pr 2O 3 into future CMOS technologies.

Impact of a Behavioral-Based Intervention on Inspiratory Muscle Training Prescription by a Multidisciplinary Team

ERIC Educational Resources Information Center

Simms, Alanna M.; Li, Linda C.; Geddes, E. Lynne; Brooks, Dina; Hoens, Alison M.; Reid, W. Darlene

2012-01-01

Introduction: Our goal was to compare behavioral- and information-based interventions aimed at increasing prescription of inspiratory muscle training (IMT) for people with chronic obstructive pulmonary disease (COPD) by interdisciplinary teams during pulmonary rehabilitation (PR). Methods: Six hospital PR programs were randomly assigned to a…

Evolutionary landscape of the Mycobacterium tuberculosis complex from the viewpoint of PhoPR: implications for virulence regulation and application to vaccine development.

PubMed

Broset, Esther; Martín, Carlos; Gonzalo-Asensio, Jesús

2015-10-20

Different members of the Mycobacterium genus have evolved to cause tuberculosis in diverse human populations and in a variety of animal species. Our cumulative knowledge of mycobacterial genomes indicates that mutations in the PhoPR two-component virulence system were acquired not only during the natural evolution of mycobacterial species but also during in vitro subculture, which has given rise to the attenuated reference strain H37Ra or to different daughter strains of Mycobacterium bovis BCG. PhoPR is a well-known regulator of pathogenic phenotypes, including secretion of the virulence factor ESAT-6, biosynthesis of acyltrehalose-based lipids, and modulation of antigen export, in members of the Mycobacterium tuberculosis complex (MTBC). Evolutionarily conserved polymorphisms in PhoPR from Mycobacterium africanum, M. bovis, or M. tuberculosis H37Ra result in loss of functional phenotypes. Interestingly, some members of the MTBC have acquired compensatory mutations to counteract these polymorphisms and, probably, to maintain their pathogenic potential. Some of these compensatory mutations include the insertion of the IS6110 element upstream from phoPR in a particular M. bovis strain that is able to transmit between humans or polymorphisms in M. africanum and M. bovis that affect the regulatory region of the espACD operon, allowing PhoPR-independent ESAT-6 secretion. This review highlights the increasing knowledge of the significance of PhoPR in the evolution of the MTBC and its potential application in the construction of new attenuated vaccines based on phoPR inactivation. In this context, the live attenuated vaccine MTBVAC, based on a phoP fadD26 deletion mutant of M. tuberculosis, is the first vaccine of this kind to successfully enter into clinical development, representing a historic milestone in the field of human vaccinology. Copyright © 2015 Broset et al.

Evolutionary Landscape of the Mycobacterium tuberculosis Complex from the Viewpoint of PhoPR: Implications for Virulence Regulation and Application to Vaccine Development

PubMed Central

Broset, Esther

2015-01-01

ABSTRACT Different members of the Mycobacterium genus have evolved to cause tuberculosis in diverse human populations and in a variety of animal species. Our cumulative knowledge of mycobacterial genomes indicates that mutations in the PhoPR two-component virulence system were acquired not only during the natural evolution of mycobacterial species but also during in vitro subculture, which has given rise to the attenuated reference strain H37Ra or to different daughter strains of Mycobacterium bovis BCG. PhoPR is a well-known regulator of pathogenic phenotypes, including secretion of the virulence factor ESAT-6, biosynthesis of acyltrehalose-based lipids, and modulation of antigen export, in members of the Mycobacterium tuberculosis complex (MTBC). Evolutionarily conserved polymorphisms in PhoPR from Mycobacterium africanum, M. bovis, or M. tuberculosis H37Ra result in loss of functional phenotypes. Interestingly, some members of the MTBC have acquired compensatory mutations to counteract these polymorphisms and, probably, to maintain their pathogenic potential. Some of these compensatory mutations include the insertion of the IS6110 element upstream from phoPR in a particular M. bovis strain that is able to transmit between humans or polymorphisms in M. africanum and M. bovis that affect the regulatory region of the espACD operon, allowing PhoPR-independent ESAT-6 secretion. This review highlights the increasing knowledge of the significance of PhoPR in the evolution of the MTBC and its potential application in the construction of new attenuated vaccines based on phoPR inactivation. In this context, the live attenuated vaccine MTBVAC, based on a phoP fadD26 deletion mutant of M. tuberculosis, is the first vaccine of this kind to successfully enter into clinical development, representing a historic milestone in the field of human vaccinology. PMID:26489860

Costs and cost-efficacy analysis of the 2017 GESIDA/Spanish National AIDS Plan recommended guidelines for initial antiretroviral therapy in HIV-infected adults.

PubMed

Rivero, Antonio; Pérez-Molina, José Antonio; Blasco, Antonio Javier; Arribas, José Ramón; Asensi, Víctor; Crespo, Manuel; Domingo, Pere; Iribarren, José Antonio; Lázaro, Pablo; López-Aldeguer, José; Lozano, Fernando; Martínez, Esteban; Moreno, Santiago; Palacios, Rosario; Pineda, Juan Antonio; Pulido, Federico; Rubio, Rafael; Santos, Jesús; de la Torre, Javier; Tuset, Montserrat; Gatell, Josep M

2018-05-01

GESIDA and the Spanish National AIDS Plan panel of experts have recommended preferred (PR), alternative (AR) and other regimens (OR) for antiretroviral therapy (ART) as initial therapy in HIV-infected patients for 2017. The objective of this study was to evaluate the costs and the efficiency of initiating treatment with PR and AR. Economic assessment of costs and efficiency (cost-efficacy) based on decision tree analyses. Efficacy was defined as the probability of reporting a viral load <50copies/mL at week 48, in an intention-to-treat analysis. Cost of initiating treatment with an ART regimen was defined as the costs of ART and its consequences (adverse effects, changes of ART regimen and drug resistance studies) during the first 48 weeks. The payer perspective (National Health System) was applied considering only differential direct costs: ART (official prices), management of adverse effects, resistance studies and HLA B*5701 screening. The setting was Spain and the costs correspond to those of 2017. A deterministic sensitivity analysis was conducted, building three scenarios for each regimen: base case, most favourable and least favourable. In the base case scenario, the cost of initiating treatment ranged from 6882 euro for TFV/FTC/RPV (AR) to 10,904 euros for TFV/FTC+RAL (PR). The efficacy varied from 0.82 for TFV/FTC+DRV/p (AR) to 0.92 for TAF/FTC/EVG/COBI (PR). The efficiency, in terms of cost-efficacy, ranged from 7923 to 12,765 euros per responder at 48 weeks, for ABC/3TC/DTG (PR) and TFV/FTC+RAL (PR), respectively. Considering ART official prices, the most efficient regimen was ABC/3TC/DTG (PR), followed by TFV/FTC/RPV (AR) and TAF/FTC/EVG/COBI (PR). Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Les accidents de la vie courante chez l’enfant à Dakar: à propos de 201 cas

PubMed Central

Mohamed, Azhar Salim; Sagna, Aloïse; Fall, Mbaye; Ndoye, Ndeye Aby; Mbaye, Papa Alassane; Fall, Aimé Lakh; Diaby, Alou; Ndour, Oumar; Ngom, Gabriel

2017-01-01

Les accidents de la vie courante (AcVC) sont fréquents chez l’enfant et peuvent être à l’origine de lésions handicapantes et de décès. L’objectif de notre travail était d’étudier les aspects épidémiologiques et lésionnels des AcVC à Dakar. C’est une étude transversale descriptive menée du 1er Janvier 2013 au 30 juin 2013. Les enfants victimes d’accidents domestiques, d’accidents de sport et de loisirs ou d’accidents scolaires ont été inclus. Nous avons étudié des paramètres généraux et des paramètres ayant trait à chaque type d’AcVC. Deux cent et un enfants ont été inclus, ce qui représentait 27% des consultations aux urgences. Il y avait 148 garçons et 53 filles. Les enfants de moins de 5 ans étaient les plus touchés (37,8%). Le football et le jeu de lutte étaient les grands pourvoyeurs d’AcVC. Les AcVC survenaient principalement à domicile (58,2%) et dans les aires de sport et de loisirs (31,8%). Les fractures prédominaient dans les différents types d’AcVC: 54,9% des accidents domestiques, 68,8% des accidents de sport et de loisirs et 40% des accidents scolaires. Au plan épidémiologique, nos résultats sont superposables à la littérature. Les fractures prédominent à l’opposé de la littérature où les contusions sont prépondérantes. Le jeu de lutte est le plus grand pourvoyeur de ces fractures après le football. La connaissance des aspects épidémiologiques et lésionnels permet de mener des campagnes de prévention des AcVC à Dakar. PMID:29187941

Optimal costs of HIV pre-exposure prophylaxis for men who have sex with men

PubMed Central

Chen, Anders; Hoover, Karen W.; Kelly, Jane; Dowdy, David; Sharifi, Parastu; Sullivan, Patrick S.; Rosenberg, Eli S.

2017-01-01

Introduction Men who have sex with men (MSM) are disproportionately affected by HIV due to their increased risk of infection. Oral pre-exposure prophylaxis (PrEP) is a highly effictive HIV-prevention strategy for MSM. Despite evidence of its effectiveness, PrEP uptake in the United States has been slow, in part due to its cost. As jurisdictions and health organizations begin to think about PrEP scale-up, the high cost to society needs to be understood. Methods We modified a previously-described decision-analysis model to estimate the cost per quality-adjusted life-year (QALY) gained, over a 1-year duration of PrEP intervention and lifetime time horizon. Using updated parameter estimates, we calculated: 1) the cost per QALY gained, stratified over 4 strata of PrEP cost (a function of both drug cost and provider costs); and 2) PrEP drug cost per year required to fall at or under 4 cost per QALY gained thresholds. Results When PrEP drug costs were reduced by 60% (with no sexual disinhibition) to 80% (assuming 25% sexual disinhibition), PrEP was cost-effective (at <$100,000 per QALY averted) in all scenarios of base-case or better adherence, as long as the background HIV prevalence was greater than 10%. For PrEP to be cost saving at base-case adherence/efficacy levels and at a background prevalence of 20%, drug cost would need to be reduced to $8,021 per year with no disinhibition, and to $2,548 with disinhibition. Conclusion Results from our analysis suggest that PrEP drug costs need to be reduced in order to be cost-effective across a range of background HIV prevalence. Moreover, our results provide guidance on the pricing of generic emtricitabine/tenofovir disoproxil fumarate, in order to provide those at high risk for HIV an affordable prevention option without financial burden on individuals or jurisdictions scaling-up coverage. PMID:28570572

Kramers non-magnetic superconductivity in LnNiAsO superconductors.

PubMed

Li, Yuke; Luo, Yongkang; Li, Lin; Chen, Bin; Xu, Xiaofeng; Dai, Jianhui; Yang, Xiaojun; Zhang, Li; Cao, Guanghan; Xu, Zhu-an

2014-10-22

We investigated a series of nickel-based oxyarsenides LnNiAsO (Ln=La, Ce, Pr, Nd, Sm) compounds. CeNiAsO undergoes two successive anti-ferromagnetic transitions at TN1=9.3 K and TN2=7.3 K; SmNiAsO becomes an anti-ferromagnet below TN≃3.5 K; NdNiAsO keeps paramagnetic down to 2 K but orders anti-ferromagnetically below TN≃1.3 K. Superconductivity was observed only in Kramers non-magnetic LaNiAsO and PrNiAsO with Tc=2.7 K and 0.93 K, respectively. The superconductivity of PrNiAsO is further studied by upper critical field and specific heat measurements, which reveal that PrNiAsO is a weakly coupled Kramers non-magnetic superconductor. Our work confirms that the nickel-based oxyarsenide superconductors are substantially different in mechanism to iron-based ones, and are likely to be described by the conventional superconductivity theory.

Controlled Crystal Grain Growth in Mixed Cation-Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells.

PubMed

Numata, Youhei; Kogo, Atsushi; Udagawa, Yosuke; Kunugita, Hideyuki; Ema, Kazuhiro; Sanehira, Yoshitaka; Miyasaka, Tsutomu

2017-06-07

We developed a new and simple solvent vapor-assisted thermal annealing (VA) procedure which can reduce grain boundaries in a perovskite film for fabricating highly efficient perovskite solar cells (PSCs). By recycling of solvent molecules evaporated from an as-prepared perovskite film as a VA vapor source, named the pot-roast VA (PR-VA) method, finely controlled and reproducible device fabrication was achieved for formamidinium (FA) and methylammonium (MA) mixed cation-halide perovskite (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 . The mixed perovskite was crystallized on a low-temperature prepared brookite TiO 2 mesoporous scaffold. When exposed to very dilute solvent vapor, small grains in the perovskite film gradually unified into large grains, resulting in grain boundaries which were highly reduced and improvement of photovoltaic performance in PSC. PR-VA-treated large grain perovskite absorbers exhibited stable photocurrent-voltage performance with high fill factor and suppressed hysteresis, achieving the best conversion efficiency of 18.5% for a 5 × 5 mm 2 device and 15.2% for a 1.0 × 1.0 cm 2 device.

Use of an ELISA-based stability assay to examine host genotype, PrP**Sc stability, and incubation time relationships in U.S. livestock prion strains

USDA-ARS?s Scientific Manuscript database

Transmissible spongiform encephalopathies (TSEs) are caused by the misfolding of the cellular prion protein (PrP**C) into a disease-associated version (PrP**Sc) that accumulates in certain tissues, leading to pathological changes in the brain and eventual death. Different strains of TSEs have been d...

The architecture of PrPSc: Threading secondary structure elements into the 4-rung ß-solenoid scaffold

USDA-ARS?s Scientific Manuscript database

Aims: We propose to exploit the wealth of theoretical and experimental constraints to develop a structure of the infectious prion (hamster PrP27-30). Recent cryo-EM based evidence has determined that PrPSc is a 4-rung ß-solenoid (Vázquez-Fernández et al. 2016, PLoS Pathog. 12(9): e1005835). This ev...

The Puerto Rico Component of the National Tsunami Hazard and Mitigation Program (PR-NTHMP)

NASA Astrophysics Data System (ADS)

Vanacore, E. A.; Huerfano Moreno, V. A.; Lopez, A. M.

2015-12-01

The Caribbean region has a documented history of damaging tsunamis that have affected coastal areas. Of particular interest is the Puerto Rico - Virgin Islands (PRVI) region, where the proximity of the coast to prominent tectonic faults would result in near-field tsunamis. Tsunami hazard assessment, detection capabilities, warning, education and outreach efforts are common tools intended to reduce loss of life and property. It is for these reasons that the PRSN is participating in an effort with local and federal agencies to develop tsunami hazard risk reduction strategies under the NTHMP. This grant supports the TsunamiReady program, which is the base of the tsunami preparedness and mitigation in PR. In order to recognize threatened communities in PR as TsunamiReady by the US NWS, the PR Component of the NTHMP have identified and modeled sources for local, regional and tele-tsunamis and the results of simulations have been used to develop tsunami response plans. The main goal of the PR-NTHMP is to strengthen resilient coastal communities that are prepared for tsunami hazards, and recognize PR as TsunamiReady. Evacuation maps were generated in three phases: First, hypothetical tsunami scenarios of potential underwater earthquakes were developed, and these scenarios were then modeled through during the second phase. The third phase consisted in determining the worst-case scenario based on the Maximum of Maximums (MOM). Inundation and evacuation zones were drawn on GIS referenced maps and aerial photographs. These products are being used by emergency managers to educate the public and develop mitigation strategies. Maps and related evacuation products, like evacuation times, can be accessed online via the PR Tsunami Decision Support Tool. Based on these evacuation maps, tsunami signs were installed, vulnerability profiles were created, communication systems to receive and disseminate tsunami messages were installed in each TWFP, and tsunami response plans were approved. Also, the existing tsunami protocol and criteria in the PR/VI was updated. This paper describes the PR-NTHMP recent outcomes, including the real time monitoring as well as the protocols used to broadcast tsunami messages. The paper highlights tsunami hazards assessment, detection, warning, education and outreach efforts in Puerto Rico.

Understanding community pharmacist perceptions and knowledge about HIV preexposure prophylaxis (PrEP) therapy in a Mountain West state.

PubMed

Unni, Elizabeth J; Lian, Nadia; Kuykendall, William

2016-01-01

Preexposure prophylaxis (PrEP) therapy is prescribed to HIV-negative individuals who are at high risk of contracting the virus to reduce the risk of transmission. Adherence to therapy is essential for optimal treatment outcome, and community pharmacists have an important role in achieving this through patient counseling. The objectives of this study were to measure pharmacists' actual knowledge about HIV PrEP therapy, perceptions about their HIV PrEP therapy knowledge, and intention to counsel patients about PrEP therapy. A cross-sectional survey was conducted among community pharmacists in Utah to measure their actual knowledge and perceptions of knowledge about PrEP therapy based on the basic information from the Centers for Disease Control website. In addition, the pharmacist's intention to counsel patients on PrEP therapy was measured with the use of the validated Godin 12-item tool. Descriptive analyses and t tests identified characteristics based on gender, degree earned, and years of practice in pharmacy. Regression analysis determined significant predictors of the intention to counsel. There were 251 responses (75% PharmD, 61% male, 42% >10 years' experience as a pharmacist). An exploratory factor analysis of the Godin 12-item tool demonstrated 4 domains: beliefs about capabilities, social influence, moral norms, and intention to counsel patients. There was no difference in the intention to counsel based on gender. Pharmacists with a PharmD and less than 10 years of experience had significantly higher knowledge and intention to counsel. The actual knowledge score of the respondents was significantly higher than their perceptions of their knowledge. Multiple regression results showed that the beliefs about capabilities and social influence were significant predictors of intention to counsel. Educating community pharmacists on PrEP therapy using pharmacists who are considered to be opinion leaders in the pharmacy profession can affect the social influence and beliefs about capabilities domains, which in turn can increase counseling on PrEP therapy. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Incidence of oral cavity and pharyngeal cancers by anatomical sites in population-based registries in Puerto Rico and the United States of America.

PubMed

Suárez, Erick; González, Lorena; Díaz-Toro, Elba C; Calo, William A; Bermúdez, Francisco; Ortiz, Ana P

2013-12-01

Puerto Rico's (PR) epidemiological data on each oral cavity and pharynx cancer (OCPC) site is yet largely unexplored. Our aim was to compare OCPC incidence in PR, by anatomical site, with that of non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Hispanic (USH) individuals in the USA. Data from the Surveillance Epidemiology and End Results program and the PR Central Cancer Registry were collected and analyzed. Age-standardized rates, percent changes, and standardized rate ratios were estimated with 95% confidence intervals. Although declining incidence rates were observed for most anatomical sites in most racial/ethnic groups and in both sexes, the incidence of oropharynx cancers slightly increased for cancers in the oropharynx among PR women, both in the base of tongue and soft palate/other oropharynx (p>0.05). The incidence of soft palate/other oropharynx cancers in PR men was about 2.8 times higher than in USH men (p<0.05) and about 1.4 times higher than in NHW men but 21% lower than in NHB men (p>0.05). Significant interactions terms formed with racial/ethnic group and age were shown in various sites. The largest differences between sexes were consistently noted in PR. Further research in PR should assess the effect of the HPV infection, as well as of other risk factors, in OCPC incidence by anatomical site in younger populations. These data could explain more precisely the reasons for the differences observed in this study, particularly among sexes in PR.

Superconducting YBa2Cu3O7- δ Thin Film Detectors for Picosecond THz Pulses

NASA Astrophysics Data System (ADS)

Probst, P.; Scheuring, A.; Hofherr, M.; Wünsch, S.; Il'in, K.; Semenov, A.; Hübers, H.-W.; Judin, V.; Müller, A.-S.; Hänisch, J.; Holzapfel, B.; Siegel, M.

2012-06-01

Ultra-fast THz detectors from superconducting YBa2Cu3O7- δ (YBCO) thin films were developed to monitor picosecond THz pulses. YBCO thin films were optimized by the introduction of CeO2 and PrBaCuO buffer layers. The transition temperature of 10 nm thick films reaches 79 K. A 15 nm thick YBCO microbridge (transition temperature—83 K, critical current density at 77 K—2.4 MA/cm2) embedded in a planar log-spiral antenna was used to detect pulsed THz radiation of the ANKA storage ring. First time resolved measurements of the multi-bunch filling pattern are presented.

Awareness and Acceptability of Pre-exposure HIV Prophylaxis Among Men Who have Sex with Men in Baltimore.

PubMed

Fallon, Susan A; Park, Ju Nyeong; Ogbue, Christine Powell; Flynn, Colin; German, Danielle

2017-05-01

This paper assessed characteristics associated with awareness of and willingness to take pre-exposure prophylaxis (PrEP) among Baltimore men who have sex with men (MSM). We used data from BESURE-MSM3, a venue-based cross-sectional HIV surveillance study conducted among MSM in 2011. Multivariate regression was used to identify characteristics associated with PrEP knowledge and acceptability among 399 participants. Eleven percent had heard of PrEP, 48% would be willing to use PrEP, and none had previously used it. In multivariable analysis, black race and perceived discrimination against those with HIV were significantly associated with decreased awareness, and those who perceived higher HIV discrimination reported higher acceptability of PrEP. Our findings indicate a need for further education about the potential utility of PrEP in addition to other prevention methods among MSM. HIV prevention efforts should address the link between discrimination and potential PrEP use, especially among men of color.

A Single Long-Term Acute Care Hospital Experience with a Pressure Ulcer Prevention Program.

PubMed

Young, Daniel L; Borris-Hale, Cathy; Falconio-West, Margaret; Chakravarthy, Debashish

2015-01-01

The occurrence of pressure ulcers (PrUs) challenges care facilities. Few studies report PrU reduction efforts in long-term acute care (LTAC). This study described the PrU reduction efforts of a single, LTAC facility using the Medline Pressure Ulcer Prevention Program (mPUPP). This study was a quasi-experimental, quality improvement project, with pre- and postmeasurement design. Outcomes were tracked for 24 months. The mPUPP was implemented in month 11. Education for caregivers was provided through an interactive web-based suite. In addition, all Patient Care Technicians attended a 4-week 1-hour inservice. New skin care products were implemented. The facility also implemented an algorithm for treatment of wounds. There was a significant reduction in the mean monthly hospital-acquired PrU (nPrU) rate when preprogram is compared to postprogram. Sustainable nPrU reduction can be achieved with mPUPP. LTAC hospitals could expect to reduce nPrU with education and incentive of caregivers. © 2014 Association of Rehabilitation Nurses.

Systemic surfaceome profiling identifies target antigens for immune-based therapy in subtypes of advanced prostate cancer

PubMed Central

Lee, John K.; Bangayan, Nathanael J.; Chai, Timothy; Smith, Bryan A.; Pariva, Tiffany E.; Yun, Sangwon; Vashisht, Ajay; Zhang, Qingfu; Park, Jung Wook; Corey, Eva; Huang, Jiaoti; Wohlschlegel, James; Witte, Owen N.

2018-01-01

Prostate cancer is a heterogeneous disease composed of divergent molecular and histologic subtypes, including prostate adenocarcinoma (PrAd) and neuroendocrine prostate cancer (NEPC). While PrAd is the major histology in prostate cancer, NEPC can evolve from PrAd as a mechanism of treatment resistance that involves a transition from an epithelial to a neurosecretory cancer phenotype. Cell surface markers are often associated with specific cell lineages and differentiation states in normal development and cancer. Here, we show that PrAd and NEPC can be broadly discriminated by cell-surface profiles based on the analysis of prostate cancer gene expression datasets. To overcome a dependence on predictions of human cell-surface genes and an assumed correlation between mRNA levels and protein expression, we integrated transcriptomic and cell-surface proteomic data generated from a panel of prostate cancer cell lines to nominate cell-surface markers associated with these cancer subtypes. FXYD3 and CEACAM5 were validated as cell-surface antigens enriched in PrAd and NEPC, respectively. Given the lack of effective treatments for NEPC, CEACAM5 appeared to be a promising target for cell-based immunotherapy. As a proof of concept, engineered chimeric antigen receptor T cells targeting CEACAM5 induced antigen-specific cytotoxicity in NEPC cell lines. Our findings demonstrate that the surfaceomes of PrAd and NEPC reflect unique cancer differentiation states and broadly represent vulnerabilities amenable to therapeutic targeting. PMID:29686080

Interface characterization of Cu-Mo coating deposited on Ti-Al alloys by arc spraying

NASA Astrophysics Data System (ADS)

Bai, Shengqiang; Li, Fei; Wu, Ting; Yin, Xianglin; Shi, Xun; Chen, Lidong

2015-03-01

Cu-Mo pseudobinary alloys are promising candidates as electrode materials in CoSb3-based skutterudite thermoelectric (TE) devices for TE power generation. In this study, Cu-Mo coatings were deposited onto Ti-Al substrates by applying a dual-wire electric arc spraying coating technique. The microstructure of the surfaces, cross sections and coating interfaces were analyzed by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). Cu-Mo coatings showed a typical banded splat with compact microstructures, and have no coarse pores nor micro-cracks. The thermal shock resistance of the Cu-Mo coating was also investigated to show good combinations with Ti-Al substrates. After 50 thermal shock cycles, there were no cracks observed at the interface. In contrast, the test of the thermal shock resistance of the Cu coating on the Ti-Al substrate was also investigated. Due to a large difference in the thermal expansion coefficients between Cu and Ti-Al alloys, the Cu coating flaked from the Ti-Al substrate completely after 10 thermal shock cycles. The contact resistivity of the Ti-Al/Cu-Mo interface was about 1.6 μΩṡcm2 and this value was unchanged after 50 thermal shock cycles, indicating the low electric resistance and high thermal stability of the Cu-Mo/Ti-Al interface.

Microstructure and thermoelectric properties of doped p-type CoSb3 under TGZM effect

NASA Astrophysics Data System (ADS)

Wang, Hongqiang; Li, Shuangming; Li, Xin; Zhong, Hong

2017-05-01

The Co-96.9 wt% Sb hypoeutectic alloy doped by 0.12 wt% YbFe was solidified in a Bridgman-type furnace based on temperature gradient zone melting (TGZM) effect. A mushy zone was observed between the complete liquid zone and the solid zone at different thermal stabilization time ranging from 15 min to 40 h. The mushy-zone solidified microstructures of the alloy only consist of CoSb3 and Sb phase. After 40 h thermal stabilization time, the volume fraction of CoSb3 in the mushy zone increases significantly up to 99.6% close to the solid-liquid interface. The hardness and fracture toughness of doped CoSb3 can reach 7.01 ± 0.69 GPa and 0.78 ± 0.08 MPa·m1/2, respectively. Meanwhile, the thermoelectric properties of the alloy were measured ranging from room temperature (RT) to 850 K. The Seebeck coefficient of the specimen prepared by TGZM effect after 40 h could reach 155 μV/K and the ZT value is 0.47 at 660 K, showing that it is feasible to prepare CoSb3 bulk material via TGZM effect. As a simple and one-step solidification method, the TGZM technique could be applied in the preparation of skutterudite compounds.

Reactions and Receptivity to Framing HIV Prevention Message Concepts About Pre-Exposure Prophylaxis for Black and Latino Men Who Have Sex with Men in Three Urban US Cities.

PubMed

Mimiaga, Matthew J; Closson, Elizabeth F; Battle, Shanice; Herbst, Jeffrey H; Denson, Damian; Pitts, Nicole; Holman, Jeremy; Landers, Stewart; Mansergh, Gordon

2016-10-01

Men who have sex with men (MSM) of color are disproportionately affected by HIV in the United States. Pre-exposure prophylaxis (PrEP) using antiretroviral medications is a newer biomedical prevention modality with established efficacy for reducing the risk of acquiring HIV. We conducted formative qualitative research to explore audience reactions and receptivity to message concepts on PrEP as part of the development of prevention messages to promote PrEP awareness among black and Latino MSM in the United States. In 2013, 48 black and 42 Latino (total study sample = 90) mixed HIV serostatus MSM from Chicago, Ft. Lauderdale, and Kansas City participated in either an individual interview or focus group discussion. Men were recruited online and at community-based organizations in each city. We elicited feedback on the comprehensibility, credibility, and relevance of two draft messages on PrEP. The messages included efficacy estimates from iPrEx, a phase III clinical trial to ascertain whether the antiretroviral medication tenofovir/emtricitabine disoproxil fumarate (commercially known as Truvada ® ) could safely and effectively prevent HIV acquisition through sex among MSM and transgender women. With participants' consent, the interviews and focus groups were recorded and transcribed. The data were then summarized and analyzed using a qualitative descriptive approach. The majority of men were unfamiliar with PrEP. It was suggested that additional information about the medication and clinical trials establishing efficacy was needed to enhance the legitimacy and relevancy of the messages. Participants sought to form an opinion of PrEP that was grounded in their own interpretation of the efficacy data. However, confusion about nonadherence among clinical trial subjects and individual versus average risk limited comprehension of these messages. Thematic overlaps suggest that message believability was connected to participants' ability to derive meaning from the PrEP efficacy data. Despite being concerned that other MSM would interpret the messages to mean that condom use was unnecessary while taking PrEP, participants themselves primarily understood PrEP as a supplement rather than a replacement for condoms. Based on their experience with taking antiretroviral medication, HIV-positive men considered condom use a more feasible form of HIV prevention than PrEP. Participants' responses suggest that more information about PrEP and the clinical trial would support the legitimacy of PrEP and the messages as a whole. These details may enhance believability in the concept of PrEP and reinforce confidence in the validity of the efficacy result.

Aqueous-based thick photoresist removal for bumping applications

NASA Astrophysics Data System (ADS)

Moore, John C.; Brewer, Alex J.; Law, Alman; Pettit, Jared M.

2015-03-01

Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

Detecting and discriminating among pathogenic protein conformers(prions), using mass spectrometry-based and antibody-based approaches(Abstract)

USDA-ARS?s Scientific Manuscript database

A set of fatal neurological diseases that includes scrapie and chronic wasting disease (CWD) are caused by a pathological protein referred to as a prion (PrPSc). A prion propagates an infection by converting a normal cellular protein (PrPC) into a prion. Unlike viral, bacterial, or fungal pathogens,...

In-line polarization rotator based on the quantum-optical analogy.

PubMed

Chen, Lei; Qu, Ke-Nan; Shen, Heng; Zhang, Wei-Gang; Chou, Keng C; Liu, Qian; Yan, Tie-Yi; Wang, Biao; Wang, Song

2016-05-01

An in-line polarization rotator (PR) is proposed based on the quantum-optical analogy (QOA). The proposed PR possesses an auxiliary E7 liquid crystal (LC) waveguide in the vicinity of the single-mode fiber (SMF) core. Because of the matched core size, the PR demonstrates good compatibility with the established backbone networks which are composed of conventional SMFs. With optimized parameters for the auxiliary waveguide, the PR offers a near 100% polarization conversion efficiency at the 1550 nm band with a bandwidth of ∼30  nm, a length of ∼4625.9  μm with a large tolerance of ∼550  μm, and a tolerance of the input light polarization angle and rotation angle of the E7 LC of ∼π/30 and ∼π/36  rad, respectively. The performance was verified by the full-vector finite-element method. The proposed PR can be easily fabricated based on the existing photonics crystal fiber manufacturing process, making it a potentially inexpensive device for applications in modern communication systems. Moreover, the QOA, compared with the previous supermode-theory design method, allows a designer to consider several waveguides separately. Therefore, various unique characteristics can be met simultaneously which is consistent with the trend of modern fiber design.

Disability relating to basic and instrumental activities of daily living: a zopulation-based study with elderly in Pelotas, Rio Grande do Sul, Brazil, 2014.

PubMed

Farías-Antúnez, Simone; Lima, Natália Peixoto; Bierhals, Isabel Oliveira; Gomes, Ana Paula; Vieira, Luna Strieder; Tomasi, Elaine

2018-06-11

to estimate the prevalence of disability related to basic and instrumental activities of daily living and its association with socioeconomic, demographic, behavioral and health characteristics in the elderly. population-based cross-sectional study in Pelotas, Brazil, in 2014; Katz and Lawton scales were used to assess the outcomes using Poisson regression. the study included 1.451 elderly individuals; the prevalence of disability for basic and instrumental activities was 36.1% and 34.0%, respectively, and 18.1% in both; higher prevalence of functional disability were observed individuals ≥80 years (PR=3.01; 95%CI 2.17;4.18), not working (PR=2.02; 95%CI 1.13;3.60) and those with multiple morbidities (PR=3.28; 95%CI 1.38;7.79); and lower in individuals with ≥12 years of schooling (PR=0.40; 95%CI 0.24;0.66), and that were physically active (PR=0.42; 95%CI 0.21;0.82). functional disability was associated to individuals older than 80, with less schooling years and affected by multiple morbidities.

Explaining the Efficacy of Pre-exposure Prophylaxis (PrEP) for HIV Prevention: A Qualitative Study of Message Framing and Messaging Preferences Among US Men Who have Sex with Men.

PubMed

Underhill, Kristen; Morrow, Kathleen M; Colleran, Christopher; Calabrese, Sarah K; Operario, Don; Salovey, Peter; Mayer, Kenneth H

2016-07-01

We investigated message comprehension and message framing preferences for communicating about PrEP efficacy with US MSM. We conducted eight focus groups (n = 38) and n = 56 individual interviews with MSM in Providence, RI. Facilitators probed comprehension, credibility, and acceptability of efficacy messages, including percentages, non-numerical paraphrases, efficacy ranges versus point estimates, and success- versus failure-framed messages. Our findings indicated a range of comprehension and operational understandings of efficacy messages. Participants tended to prefer percentage-based and success-framed messages, although preferences varied for communicating about efficacy using a single percentage versus a range. Participants reported uncertainty about how to interpret numerical estimates, and many questioned whether trial results would predict personal effectiveness. These results suggest that providers and researchers implementing PrEP may face challenges in communicating with users about efficacy. Efforts to educate MSM about PrEP should incorporate percentage-based information, and message framing decisions may influence message credibility and overall PrEP acceptability.

Cerium LIII-edge x-ray absorption study of the CexFe4-yCoySb12 skutterudites

NASA Astrophysics Data System (ADS)

Grandjean, Fernande; Long, Gary J.; Cortes, Robert; Morelli, Donald T.; Meisner, Gregory P.

2000-11-01

The cerium LIII-edge x-ray absorption near-edge spectra of the CexFe4-yCoySb12 compounds have been obtained at 295 K and unambiguously indicate that cerium is in the 4f1 electronic ground state for all values of 0.22<=x<=0.98 and 0.0<=y<=3.5. This stable trivalent state of cerium is in agreement with the proposed (CeFe4Sb12)1-α(□Co4Sb12)α, solid solution structure, in which the cerium atoms are always surrounded by twelve antimony first neighbors and six iron second neighbors, the observed magnetic properties of CeFe4Sb12 and Ce0.9Fe3CoSb12, and the electronic structure of CeFe4Sb12 obtained from band-structure calculations.

Crystal Structure and Properties of Imidazo-Pyridine Ionic Liquids.

PubMed

Farren-Dai, Marco; Cameron, Stanley; Johnson, Michel B; Ghandi, Khashayar

2018-07-05

Computational studies were performed on novel protic ionic liquids imidazolium-[1,2-a]-pyridine trifluoroacetate [ImPr][TFA] synthesized by the reaction of imidazo-[1,2a]-pyridine (ImPr) with trifluoroacetic acid (TFA), and on fused salt imidazolium-[1,2-a]-pyridine maleamic carbonate [ImPr][Mal] synthesized by reaction of ImPr with maleamic acid (Mal). Synthesis was performed as one-pot reactions, which applies green chemistry tenets. Both these compounds begin to decompose at 180°C. Our computational studies suggest another thermal reaction channel, in which [ImPr][Mal] can also thermally polymerizes to polyacrylamide which then cyclizes. This is thermal product remains stable up to 700 degrees, consistent with our thermogravimetric studies. [ImPr][TFA] exhibited good conductivity and ideal ionic behavior, as evaluated by a Walden plot. X-ray crystallography of [ImPr][TFA] revealed a tightly packed system for the crystals as a result of strong ionic interaction, pi-stacking, and fluorine-CH interactions. Both synthesized compounds exhibited some CO 2 absorptivity, with [ImPr][Mal] outperforming [ImPr][TFA] in this regard. The quantum chemistry based computational methods can shed light on many properties of these ionic liquids, but they are challenged in fully describing their ionic nature. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

PrEP implementation research in Africa: what is new?

PubMed

Cowan, Frances M; Delany-Moretlwe, Sinead; Sanders, Eduard J; Mugo, Nelly R; Guedou, Fernand A; Alary, Michel; Behanzin, Luc; Mugurungi, Owen; Bekker, Linda-Gail

2016-01-01

Of the two million new HIV infections in adults in 2014, 70% occurred in sub-Saharan Africa. Several African countries have already approved guidelines for pre-exposure prophylaxis (PrEP) for individuals at substantial risk of HIV as part of combination HIV prevention but key questions remain about how to identify and deliver PrEP to those at greatest need. Throughout the continent, individuals in sero-discordant relationships, and members of key populations (sex workers, men who have sex with men (MSM), transgender women and injection drug users) are likely to benefit from the availability of PrEP. In addition, adolescent girls and young women (AGYW) are at substantial risk in some parts of the continent. It has been estimated that at least three million individuals in Africa are likely to be eligible for PrEP according to WHO's criteria. Tens of demonstration projects are planned or underway across the continent among a range of countries, populations and delivery settings. In each of the target populations, there are overarching issues related to (i) creating demand for PrEP, (ii) addressing supply-side issues and (iii) providing appropriate and tailored adherence support. Critical for creating demand for PrEP is the normalization of HIV prevention. Community-level interventions which engage opinion leaders as well as empowerment interventions for those at highest risk will be key. Critical to supply of PrEP is that services are accessible for all, including for stigmatized populations. Establishing accessible integrated services provides the opportunity to address other public health priorities including the unmet need for HIV testing, contraception and sexually transmitted infections treatment. National policies need to include minimum standards for training and quality assurance for PrEP implementation and to address supply chain issues. Adherence support needs to recognize that social and structural factors are likely to have an important influence. Combining interventions that build self-efficacy, empowerment and social cohesion, with evidence-based individualized adherence support for PrEP, are most likely to be effective. Efficacy of tenfovir-based PrEP is proven but many issues related to implementation remain unclear. Here, we have summarized some of the important implementation questions that need to be assessed as PrEP is rolled out across Africa.

PrEP implementation research in Africa: what is new?

PubMed Central

Cowan, Frances M; Delany-Moretlwe, Sinead; Sanders, Eduard J; Mugo, Nelly R; Guedou, Fernand A; Alary, Michel; Behanzin, Luc; Mugurungi, Owen; Bekker, Linda-Gail

2016-01-01

Introduction Of the two million new HIV infections in adults in 2014, 70% occurred in sub-Saharan Africa. Several African countries have already approved guidelines for pre-exposure prophylaxis (PrEP) for individuals at substantial risk of HIV as part of combination HIV prevention but key questions remain about how to identify and deliver PrEP to those at greatest need. Throughout the continent, individuals in sero-discordant relationships, and members of key populations (sex workers, men who have sex with men (MSM), transgender women and injection drug users) are likely to benefit from the availability of PrEP. In addition, adolescent girls and young women (AGYW) are at substantial risk in some parts of the continent. It has been estimated that at least three million individuals in Africa are likely to be eligible for PrEP according to WHO's criteria. Tens of demonstration projects are planned or underway across the continent among a range of countries, populations and delivery settings. Discussion In each of the target populations, there are overarching issues related to (i) creating demand for PrEP, (ii) addressing supply-side issues and (iii) providing appropriate and tailored adherence support. Critical for creating demand for PrEP is the normalization of HIV prevention. Community-level interventions which engage opinion leaders as well as empowerment interventions for those at highest risk will be key. Critical to supply of PrEP is that services are accessible for all, including for stigmatized populations. Establishing accessible integrated services provides the opportunity to address other public health priorities including the unmet need for HIV testing, contraception and sexually transmitted infections treatment. National policies need to include minimum standards for training and quality assurance for PrEP implementation and to address supply chain issues. Adherence support needs to recognize that social and structural factors are likely to have an important influence. Combining interventions that build self-efficacy, empowerment and social cohesion, with evidence-based individualized adherence support for PrEP, are most likely to be effective. Conclusions Efficacy of tenfovir-based PrEP is proven but many issues related to implementation remain unclear. Here, we have summarized some of the important implementation questions that need to be assessed as PrEP is rolled out across Africa. PMID:27760680

Recent revisions of phosphate rock reserves and resources: reassuring or misleading? An in-depth literature review of global estimates of phosphate rock reserves and resources

NASA Astrophysics Data System (ADS)

Edixhoven, J. D.; Gupta, J.; Savenije, H. H. G.

2013-09-01

Phosphate rock (PR) is a finite mineral indispensible for fertilizer production and a major pollutant. High grade PR is obtained from deposits which took millions of years to form and are gradually being depleted. Over the past three years, global PR reserves as reported by US Geological Survey (USGS) have seen a massive increase, from 16 000 Mt PR in 2010 to 65 000 Mt PR in 2011. The bulk of this four-fold increase is based on a 2010 report by International Fertilizer Development Center (IFDC), which increased Moroccan reserves from 5700 Mt PR as reported by USGS, to 51 000 Mt PR, reported as upgraded ("beneficiated") concentrate. IFDC used a starkly simplified classification compared to the classification used by USGS and proposed that agreement should be reached on PR resource terminology which should be as simple as possible. The report has profoundly influenced the PR scarcity debate, shifting the emphasis from depletion to the pollution angle of the phosphate problem. Various analysts adopted the findings of IFDC and USGS, and argued that that following depletion of reserves, uneconomic deposits (resources and occurrences) will remain available which will extend the lifetime of available deposits to thousands of years. Given the near total dependence of food production on PR, data on PR deposits must be transparent, comparable, reliable and credible. Based on an in-depth literature review, we analyze (i) how IFDC's simplified terminology compares to international best practice in resource classification and whether it is likely to yield data that meets the abovementioned requirements; (ii) whether the difference between ore reserves and reserves as concentrate is sufficiently noted in the literature, and (iii) whether the IFDC report and its estimate of PR reserves and resources is reliable. We conclude that, while there is a global development toward common criteria in resource reporting, IFDC's definitions contravene this development and - due to their vagueness and their lack of granularity - may cause more confusion than clarity. The difference between ore and concentrate is barely noted in the literature, causing a pervasive confusion and a high degree of error in many assessments. Finally, we conclude that the report presents an inflated picture of global reserves, in particular those of Morocco, where largely hypothetical and inferred resources have simply been converted to "reserves". In view of the essentiality of PR for food production, there currently is insufficient knowledge on the PR deposits available for extraction. Further research is required as to the quantity of PR deposits and their viability for future extraction.

A proteorhodopsin-based biohybrid light-powering pH sensor.

PubMed

Rao, Siyuan; Guo, Zhibin; Liang, Dawei; Chen, Deliang; Wei, Yen; Xiang, Yan

2013-10-14

The biohybrid sensor is an emerging technique for multi-functional detection that utilizes the instinctive responses or interactions of biomolecules. We develop a biohybrid pH sensor by taking advantage of the pH-dependent photoelectric characteristics of proteorhodopsin (pR). The transient absorption kinetics study indicates that the photoelectric behavior of pR is attributed to the varying lifetime of the M intermediate at different environmental pH values. This pR-based biohybrid light-powering sensor with microfluidic design can achieve real-time pH detection with quick response and high sensitivity. The results of this work would shed light on pR and its potential applications.

PrAS: Prediction of amidation sites using multiple feature extraction.

PubMed

Wang, Tong; Zheng, Wei; Wuyun, Qiqige; Wu, Zhenfeng; Ruan, Jishou; Hu, Gang; Gao, Jianzhao

2017-02-01

Amidation plays an important role in a variety of pathological processes and serious diseases like neural dysfunction and hypertension. However, identification of protein amidation sites through traditional experimental methods is time consuming and expensive. In this paper, we proposed a novel predictor for Prediction of Amidation Sites (PrAS), which is the first software package for academic users. The method incorporated four representative feature types, which are position-based features, physicochemical and biochemical properties features, predicted structure-based features and evolutionary information features. A novel feature selection method, positive contribution feature selection was proposed to optimize features. PrAS achieved AUC of 0.96, accuracy of 92.1%, sensitivity of 81.2%, specificity of 94.9% and MCC of 0.76 on the independent test set. PrAS is freely available at https://sourceforge.net/p/praspkg. Copyright © 2016 Elsevier Ltd. All rights reserved.

Piperazine derivatives inhibit PrP/PrP(res) propagation in vitro and in vivo.

PubMed

Leidel, Fabienne; Eiden, Martin; Geissen, Markus; Hirschberger, Thomas; Tavan, Paul; Giese, Armin; Kretzschmar, Hans A; Schätzl, Hermann; Groschup, Martin H

2014-02-28

Prion diseases are fatal neurodegenerative disorders, which are not curable and no effective treatment exists so far. The major neuropathological change in diseased brains is the conversion of the normal cellular form of the prion protein PrPc(C) into a disease-associated isoform PrP(Sc). PrP(Sc) accumulates into multimeres and fibrillar aggregates, which leads to the formation of amyloid plaques. Increasing evidence indicates a fundamental role of PrP(Sc) species and its aggregation in the pathogenesis of prion diseases, which initiates the pathological cascade and leads to neurodegeneration accompanied by spongiform changes. In search of compounds that have the potential to interfere with PrP(Sc) formation and propagation, we used a cell based assay for the screening of potential aggregation inhibitors. The assay deals with a permanently prion infected cell line that was adapted for a high-throughput screening of a compound library composed of 10,000 compounds (DIVERset 2, ChemBridge). We could detect six different classes of highly potent inhibitors of PrP(Sc) propagation in vitro and identified piperazine derivatives as a new inhibitory lead structure, which increased incubation time of scrapie infected mice. Copyright © 2014 Elsevier Inc. All rights reserved.

Discovery of small molecules binding to the normal conformation of prion by combining virtual screening and multiple biological activity evaluation methods

NASA Astrophysics Data System (ADS)

Li, Lanlan; Wei, Wei; Jia, Wen-Juan; Zhu, Yongchang; Zhang, Yan; Chen, Jiang-Huai; Tian, Jiaqi; Liu, Huanxiang; He, Yong-Xing; Yao, Xiaojun

2017-12-01

Conformational conversion of the normal cellular prion protein, PrPC, into the misfolded isoform, PrPSc, is considered to be a central event in the development of fatal neurodegenerative diseases. Stabilization of prion protein at the normal cellular form (PrPC) with small molecules is a rational and efficient strategy for treatment of prion related diseases. However, few compounds have been identified as potent prion inhibitors by binding to the normal conformation of prion. In this work, to rational screening of inhibitors capable of stabilizing cellular form of prion protein, multiple approaches combining docking-based virtual screening, steady-state fluorescence quenching, surface plasmon resonance and thioflavin T fluorescence assay were used to discover new compounds interrupting PrPC to PrPSc conversion. Compound 3253-0207 that can bind to PrPC with micromolar affinity and inhibit prion fibrillation was identified from small molecule databases. Molecular dynamics simulation indicated that compound 3253-0207 can bind to the hotspot residues in the binding pocket composed by β1, β2 and α2, which are significant structure moieties in conversion from PrPC to PrPSc.

HIV-1 protease has a genetic T-cell adjuvant effect which is negatively regulated by proteolytic activity.

PubMed

Kim, Kwang Soon; Jin, Dong Bin; Ahn, So Shin; Park, Ki Seok; Seo, Sang Hwan; Suh, You Suk; Sung, Young Chul

2010-08-01

HIV protease (PR) mediates the processing of human immunodeficiency virus (HIV) polyproteins and is necessary for the viral production. Recently, HIV PR was shown to possess both cytotoxic and chaperone like activity. We demonstrate here that HIV PR can serve as a genetic adjuvant that enhances the HIV Env and human papillomavirus (HPV) DNA vaccine-induced T-cell response in a dose-dependent manner, only when codelivered with DNA vaccine. Interestingly, the T-cell adjuvant effects of HIV PR were increased by introducing several mutations that inhibited its proteolytic activity, indicating that the adjuvant properties were inversely correlated with its proteolytic activity. Conversely, the introduction of a mutation in the flap region of HIV PR limiting the access to the core domain of HIV PR inhibited the T-cell adjuvant effect, suggesting that the HIV PR chaperone like activity may play a role in mediating T-cell adjuvant properties. A similar adjuvant effect was also observed in adenovirus vaccine, indicating vaccine type independency. These findings suggest that HIV PR can modulate T-cell responses elicited by a gene-based vaccine positively by inherent chaperone like activity and negatively by its proteolytic activity.

Antiviral activities of 2,6-diaminopurine-based acyclic nucleoside phosphonates against herpesviruses: In vitro study results with pseudorabies virus (PrV, SuHV-1).

PubMed

Zouharova, Darina; Lipenska, Ivana; Fojtikova, Martina; Kulich, Pavel; Neca, Jiri; Slany, Michal; Kovarcik, Kamil; Turanek-Knotigova, Pavlina; Hubatka, Frantisek; Celechovska, Hana; Masek, Josef; Koudelka, Stepan; Prochazka, Lubomir; Eyer, Ludek; Plockova, Jana; Bartheldyova, Eliska; Miller, Andrew D; Ruzek, Daniel; Raska, Milan; Janeba, Zlatko; Turanek, Jaroslav

2016-02-29

Pseudorabies virus (PrV), a causative agent of Aujeszky's disease, is deadly to most mammals with the exception of higher primates and men. This disease causes serious economic loses among farm animals, especially pigs, yet many European countries are today claimed to be Aujeszky's disease free because of the discovery of an efficient vaccination for pigs. In reality, the virus is still present in wild boar. Current vaccines are neither suitable for dogs nor are there anti-PrV drugs approved for veterinary use. Therefore, the disease still represents a high threat, particularly for expensive hunting dogs that can come into close contact with infected boars. Here we report on the anti-PrV activities of a series of synthetic diaminopurine-based acyclic nucleoside phosphonate (DAP-ANP) analogues. Initially, all synthetic DAP-ANPs under investigation are shown to exhibit minimal cytotoxicity by MTT and XTT tests (1-100μM range). Thereafter in vitro infection models are established using PrV virus SuHV-1, optimized on PK-15 and RK-13 cell lines. Out of the six DAP-ANP analogues tested, analogue VI functionalized with a cyclopropyl group on the 6-amino position of the purine ring proves the most effective antiviral DAP-ANP analogue against PrV infection, aided by sufficient hydrophobic character to enhance bioavailability to its cellular target viral DNA-polymerase. Four other DAP-ANP analogues with functional groups introduced to the C2'position are shown ineffective against PrV infection, even with favourable hydrophobic properties. Cidofovir(®), a drug approved against various herpesvirus infections, is found to exert only low activity against PrV in these same in vitro models. Copyright © 2016 Elsevier B.V. All rights reserved.

Aspects of mutually unbiased bases in odd-prime-power dimensions

NASA Astrophysics Data System (ADS)

Chaturvedi, S.

2002-04-01

We rephrase the Wootters-Fields construction [W. K. Wootters and B. C. Fields, Ann. Phys. 191, 363 (1989)] of a full set of mutually unbiased bases in a complex vector space of dimensions N=pr, where p is an odd prime, in terms of the character vectors of the cyclic group G of order p. This form may be useful in explicitly writing down mutually unbiased bases for N=pr.

Modeling and Fault Simulation of Propellant Filling System

NASA Astrophysics Data System (ADS)

Jiang, Yunchun; Liu, Weidong; Hou, Xiaobo

2012-05-01

Propellant filling system is one of the key ground plants in launching site of rocket that use liquid propellant. There is an urgent demand for ensuring and improving its reliability and safety, and there is no doubt that Failure Mode Effect Analysis (FMEA) is a good approach to meet it. Driven by the request to get more fault information for FMEA, and because of the high expense of propellant filling, in this paper, the working process of the propellant filling system in fault condition was studied by simulating based on AMESim. Firstly, based on analyzing its structure and function, the filling system was modular decomposed, and the mathematic models of every module were given, based on which the whole filling system was modeled in AMESim. Secondly, a general method of fault injecting into dynamic system was proposed, and as an example, two typical faults - leakage and blockage - were injected into the model of filling system, based on which one can get two fault models in AMESim. After that, fault simulation was processed and the dynamic characteristics of several key parameters were analyzed under fault conditions. The results show that the model can simulate effectively the two faults, and can be used to provide guidance for the filling system maintain and amelioration.

Novel technique: a pupillometer-based objective chromatic perimetry

NASA Astrophysics Data System (ADS)

Rotenstreich, Ygal; Skaat, Alon; Sher, Ifat; Kolker, Andru; Rosenfeld, Elkana; Melamed, Shlomo; Belkin, Michael

2014-02-01

Evaluation of visual field (VF) is important for clinical diagnosis and patient monitoring. The current VF methods are subjective and require patient cooperation. Here we developed a novel objective perimetry technique based on the pupil response (PR) to multifocal chromatic stimuli in normal subjects and in patients with glaucoma and retinitis pigmentosa (RP). A computerized infrared video pupillometer was used to record PR to short- and long-wavelength stimuli (peak 485 nm and 620 nm, respectively) at light intensities of 15-100 cd-s/m2 at thirteen different points of the VF. The RP study included 30 eyes of 16 patients and 20 eyes of 12 healthy participants. The glaucoma study included 22 eyes of 11 patients and 38 eyes of 19 healthy participants. Significantly reduced PR was observed in RP patients in response to short-wavelength stimuli at 40 cd-s/m2 in nearly all perimetric locations (P <0.05). By contrast, RP patients demonstrated nearly normal PR to long-wavelength in majority of perimetric locations. The glaucoma group showed significantly reduced PR to long- and short-wavelength stimuli at high intensity in all perimetric locations (P <0.05). The PR of glaucoma patients was significantly lower than normal in response to short-wavelength stimuli at low intensity mostly in central and 20° locations (p<0.05). This study demonstrates the feasibility of using pupillometer-based chromatic perimetry for objectively assessing VF defects and retinal function and optic nerve damage in patients with retinal dystrophies and glaucoma. Furthermore, this method may be used to distinguish between the damaged cells underlying the VF defect.

Catalytic transfer hydrogenation with terdentate CNN ruthenium complexes: the influence of the base.

PubMed

Baratta, Walter; Siega, Katia; Rigo, Pierluigi

2007-01-01

The catalytic activity of the terdentate complex [RuCl(CNN)(dppb)] (A) [dppb=Ph(2)P(CH(2))(4)PPh(2); HCNN=6-(4'-methylphenyl)-2-pyridylmethylamine] in the transfer hydrogenation of acetophenone (S) with 2-propanol has been found to be dependent on the base concentration. The limit rate has been observed when NaOiPr is used in high excess (A/base molar ratio > 10). The amino-isopropoxide species [Ru(OiPr)(CNN)(dppb)] (B), which forms by reaction of A with sodium isopropoxide via displacement of the chloride, is catalytically active. The rate of conversion of acetophenone obeys second-order kinetics v=k[S][B] with the rate constants in the range 218+/-8 (40 degrees C) to 3000+/-70 M(-1) s(-1) (80 degrees C). The activation parameters, evaluated from the Eyring equation are DeltaH(++)=14.0+/-0.2 kcal mol(-1) and DeltaS(++)=-3.2 +/-0.5 eu. In a pre-equilibrium reaction with 2-propanol complex B gives the cationic species [Ru(CNN)(dppb)(HOiPr)](+)[OiPr](-) (C) with K approximately 2x10(-5) M. The hydride species [RuH(CNN)(dppb)] (H), which forms from B via beta-hydrogen elimination process, catalyzes the reduction of S and, importantly, its activity increases by addition of base. The catalytic behavior of the hydride H has been compared to that of the system A/NaOiPr (1:1 molar ratio) and indicates that the two systems are equivalent.

Pre-exposure Prophylaxis Awareness Among Gay and Other Men who have Sex with Men in Vancouver, British Columbia, Canada.

PubMed

Lachowsky, Nathan J; Lin, Sally Y; Hull, Mark W; Cui, Zishan; Sereda, Paul; Jollimore, Jody; Rich, Ashleigh; Montaner, Julio S G; Roth, Eric A; Hogg, Robert S; Moore, David M

2016-07-01

Men who have sex with men (MSM) account for approximately half of Canada's new HIV infections. Pre-exposure prophylaxis (PrEP), a recently established and effective HIV prevention tool for MSM is currently not approved nor publicly funded. We recruited MSM via respondent-driven sampling to complete a self-administered computer-based interview. Stratified by HIV status, multivariable logistic regression identified factors associated with PrEP awareness. Of 673 participants, 102/500 (20.9 %) HIV-negative and 63/173 (26.5 %) HIV-positive men were aware of PrEP, but none had used it. One third of PrEP-aware MSM spoke about it with friends or sex partners. Self-declared knowledge was limited. Factors associated with PrEP awareness varied by HIV status, but included greater HAART optimism for HIV-negative MSM. Among HIV-negative MSM, being PrEP unaware was associated with younger age, not always having condoms, and preferring receptive versus insertive anal sex. Future longitudinal research should identify early adopters of PrEP and its associated impacts.

Pre-Exposure Prophylaxis Awareness Among Gay and Other Men who have Sex with Men in Vancouver, British Columbia, Canada

PubMed Central

Lachowsky, Nathan J; Lin, Sally Y; Hull, Mark W; Cui, Zishan; Sereda, Paul; Jollimore, Jody; Rich, Ashleigh; Montaner, Julio SG; Roth, Eric A; Hogg, Robert S; Moore, David M

2016-01-01

Men who have sex with men (MSM) account for approximately half of Canada’s new HIV infections. Pre-exposure prophylaxis (PrEP), a recently established and effective HIV prevention tool for MSM is currently not approved nor publicly funded. We recruited MSM via respondent-driven sampling to complete a self-administered computer-based interview. Stratified by HIV status, multivariable logistic regression identified factors associated with PrEP awareness. Of 673 participants, 102/500 (20.9%) HIV-negative and 63/173 (26.5%) HIV-positive men were aware of PrEP, but none had used it. One third of PrEP-aware MSM spoke about it with friends or sex partners. Self-declared knowledge was limited. Factors associated with PrEP awareness varied by HIV status, but included greater HAART optimism for HIV-negative MSM. Among HIV-negative MSM, being PrEP unaware was associated with younger age, not always having condoms, and preferring receptive versus insertive anal sex. Future longitudinal research should identify early adopters of PrEP and its associated impacts. PMID:26884310

La prévention des blessures chez les enfants et les adolescents : une démarche de santé publique

PubMed Central

Yanchar, Natalie L; Warda, Lynne J; Fuselli, Pamela

2012-01-01

RÉSUMÉ La majorité des blessures dont sont victimes les enfants et les adolescents sont évitables. Le présent document de principes contient des renseignements généraux, des conseils et une déclaration d’engagement à l’égard de la prévention des blessures au Canada. Il sert de base sur laquelle construire en s’attardant d’abord aux définitions, à l’étendue et aux priorités en matière de prévention des blessures. Il contient également une description du fardeau et du profil des blessures non intentionnelles, de même que les principes d’interventions de prévention efficaces. La version intégrale renferme une liste de ressources en vue d’obtenir des données et de l’information probante (www.cps.ca). Enfin, le présent document de principes peut être utilisé pour la défense généralisée de la prévention des blessures.

Biochemical Characterization of Prion Strains in Bank Voles

PubMed Central

Pirisinu, Laura; Marcon, Stefano; Di Bari, Michele Angelo; D’Agostino, Claudia; Agrimi, Umberto; Nonno, Romolo

2013-01-01

Prions exist as different strains exhibiting distinct disease phenotypes. Currently, the identification of prion strains is still based on biological strain typing in rodents. However, it has been shown that prion strains may be associated with distinct PrPSc biochemical types. Taking advantage of the availability of several prion strains adapted to a novel rodent model, the bank vole, we investigated if any prion strain was actually associated with distinctive PrPSc biochemical characteristics and if it was possible to univocally identify strains through PrPSc biochemical phenotypes. We selected six different vole-adapted strains (three human-derived and three animal-derived) and analyzed PrPSc from individual voles by epitope mapping of protease resistant core of PrPSc (PrPres) and by conformational stability and solubility assay. Overall, we discriminated five out of six prion strains, while two different scrapie strains showed identical PrPSc types. Our results suggest that the biochemical strain typing approach here proposed was highly discriminative, although by itself it did not allow us to identify all prion strains analyzed. PMID:25437201

Filling the voids in the SRTM elevation model — A TIN-based delta surface approach

NASA Astrophysics Data System (ADS)

Luedeling, Eike; Siebert, Stefan; Buerkert, Andreas

The Digital Elevation Model (DEM) derived from NASA's Shuttle Radar Topography Mission is the most accurate near-global elevation model that is publicly available. However, it contains many data voids, mostly in mountainous terrain. This problem is particularly severe in the rugged Oman Mountains. This study presents a method to fill these voids using a fill surface derived from Russian military maps. For this we developed a new method, which is based on Triangular Irregular Networks (TINs). For each void, we extracted points around the edge of the void from the SRTM DEM and the fill surface. TINs were calculated from these points and converted to a base surface for each dataset. The fill base surface was subtracted from the fill surface, and the result added to the SRTM base surface. The fill surface could then seamlessly be merged with the SRTM DEM. For validation, we compared the resulting DEM to the original SRTM surface, to the fill DEM and to a surface calculated by the International Center for Tropical Agriculture (CIAT) from the SRTM data. We calculated the differences between measured GPS positions and the respective surfaces for 187,500 points throughout the mountain range (ΔGPS). Comparison of the means and standard deviations of these values showed that for the void areas, the fill surface was most accurate, with a standard deviation of the ΔGPS from the mean ΔGPS of 69 m, and only little accuracy was lost by merging it to the SRTM surface (standard deviation of 76 m). The CIAT model was much less accurate in these areas (standard deviation of 128 m). The results show that our method is capable of transferring the relative vertical accuracy of a fill surface to the void areas in the SRTM model, without introducing uncertainties about the absolute elevation of the fill surface. It is well suited for datasets with varying altitude biases, which is a common problem of older topographic information.

Biochemical Characterization of Prions.

PubMed

Fiorini, Michele; Bongianni, Matilde; Monaco, Salvatore; Zanusso, Gianluigi

2017-01-01

Prion disease or transmissible spongiform encephalopathies are characterized by the presence of the abnormal form of the prion protein (PrP Sc ). The pathological and transmissible properties of PrP Sc are enciphered in its secondary and tertiary structures. Since it's well established that different strains of prions are linked to different conformations of PrP Sc , biochemical characterization of prions seems a preliminary but reliable approach to detect, analyze, and compare prion strains. Experimental biochemical procedures might be helpful in distinguishing PrP Sc physicochemical properties and include resistance to proteinase K (PK) digestion, insolubility in nonionic detergents, PK-resistance under denaturing conditions and sedimentation properties in sucrose gradients. This biochemical approach has been extensively applied in human prion disorders and subsequently expanded for PrP Sc characterization in animals. In particular, in sporadic Creutzfedlt-Jakob disease (sCJD) PrP Sc is characterized by two main glycotypes conventionally named Type 1 and Type 2, based on the apparent gel migration at 21 and 19kDa of the PrP Sc PK-resistant fragment. An additional PrP Sc type was identified in sCJD characterized by an unglycosylated dominant glycoform pattern and in 2010 a variably protease-sensitive prionopathy (VPSPr) was reported showing a PrP Sc with an electrophoretic ladder like pattern. Additionally, the presence of PrP Sc truncated fragments completes the electrophoretic characterization of different prion strains. By two-dimensional (2D) electrophoretic analysis additional PrP Sc pattern was identified, since this procedure provides information about the isoelectric point and the different peptides length related to PK cleavage, as well as to glycosylation extent or GPI anchor presence. We here provide and extensive review on PrP Sc biochemical analysis in human and animal prion disorders. Further, we show that PrP Sc glycotypes observed in CJD share similarities with PrP Sc in bovine spongiform encephalopathy forms (BSE). © 2017 Elsevier Inc. All rights reserved.

Pre-exposure prophylaxis of HIV

PubMed Central

Naswa, Smriti; Marfatia, Y. S.

2011-01-01

Pre-exposure prophylaxis (PrEP) is an experimental approach to HIV prevention and consists of antiretroviral drugs to be taken before potential HIV exposure in order to reduce the risk of HIV infection and continued during periods of risk. An effective PrEP could provide an additional safety net to sexually active persons at risk, when combined with other prevention strategies. Women represent nearly 60% of adults infected with HIV and PrEP can be a female-controlled prevention method for women who are unable to negotiate condom use. Two antiretroviral nucleoside analog HIV-1 reverse transcriptase inhibitor drugs are currently under trial as PrEP drugs, namely tenofovirdisoproxilfumarate (TDF) alone and TDF in combination with emricitabine (FTC), to be taken as daily single dose oral drugs. There are 11 ongoing trials of ARV-based prevention in different at risk populations across the world. The iPrex trial showed that daily use of oral TDF/FTC by MSM resulted in 44% reduction in the incidence of HIV. This led to publication of interim guidance by CDC to use of PrEP by health providers for MSM. Few other trials are Bangkok Tenofovir Study, Partners PrEP Study, FEM-PrEP study, and VOICE (MTN-003) study. Future trials are being formulated for intermittent PrEP (iPrEP) where drugs are taken before and after sex, “stand-in dose” iPrEP, vaginal or rectal PrEP, etc. There are various issues/concerns with PrEP such as ADRs and resistance to TDF/FTC, adherence to drugs, acceptability, sexual disinhibition, use of PrEP as first line of defense for HIV without other prevention strategies, and cost. The PrEP has a potential to address unmet need in public health if delivered as a part of comprehensive toolkit of prevention services, including risk-reduction, correct and consistent use of condoms, and diagnosis and treatment of sexually transmitted infections. PMID:21799568

Pre-Exposure Prophylaxis for HIV Prevention: Safety Concerns.

PubMed

Tetteh, Raymond A; Yankey, Barbara A; Nartey, Edmund T; Lartey, Margaret; Leufkens, Hubert G M; Dodoo, Alexander N O

2017-04-01

Available evidence supports the efficacy of pre-exposure prophylaxis (PrEP) in decreasing the incidence of human immunodeficiency virus (HIV) infection among high-risk individuals, especially when used in combination with other behavioural preventive methods. Safety concerns about PrEP present challenges in the implementation and use of PrEP. The aim of this review is to discuss safety concerns observed in completed clinical trials on the use of PrEP. We performed a literature search on PrEP in PubMed, global advocacy for HIV prevention (Aids Vaccine Advocacy Coalition) database, clinical trials registry " http://www.clinicaltrials.gov " and scholar.google, using combination search terms 'pre-exposure prophylaxis', 'safety concerns in the use of pre-exposure prophylaxis', 'truvada use as PrEP', 'guidelines for PrEP use', 'HIV pre-exposure prophylaxis' and 'tenofovir' to identify clinical trials and literature on PrEP. We present findings associated with safety issues on the use of PrEP based on a review of 11 clinical trials on PrEP with results on safety and efficacy as at April 2016. We also reviewed findings from routine real-life practice reports. The pharmacological intervention for PrEP was tenofovir disoproxil fumarate/emtricitabine in a combined form as Truvada ® or tenofovir as a single entity. Both products are efficacious for PrEP and seem to have a good safety profile. Regular monitoring is recommended to prevent long-term toxic effects. The main adverse effects observed with PrEP are gastrointestinal related; basically mild to moderate nausea, vomiting and diarrhea. Other adverse drug effects worth monitoring are liver enzymes, renal function and bone mineral density. PrEP as an intervention to reduce HIV transmission appears to have a safe benefit-risk profile in clinical trials. It is recommended for widespread use but adherence monitoring and real-world safety surveillance are critical in the post-marketing phase to ensure that the benefits observed in clinical trials are maintained in real-world use.

Azole Functionalized Polyoxo-Titanium Clusters with Sunlight-Driven Dye Degradation Applications: Synthesis, Structure, and Photocatalytic Studies.

PubMed

Narayanam, Nagaraju; Chintakrinda, Kalpana; Fang, Wei-Hui; Kang, Yao; Zhang, Lei; Zhang, Jian

2016-10-06

Six polyoxo-titanium clusters (PTCs) with varying nuclearities containing Ti-N bonds and heteronuclearity, namely, [Ti 6 (μ 3 -O) 2 (μ 2 -O) 2 (O 3 P-Phen) 2 (OiPr) 10 (1-hbta) 2 ] (PTC-37), Ti 8 (μ 3 -O) 2 (μ 2 -O) 2 (O 3 P-Phen) 2 (OiPr) 16 (adn) 2 (NO 3 ) 2 ] (PTC-38), [Ti 4 (μ 3 -O)(μ 2 -O)(μ 2 -OiPr) 2 (OiPr) 4 (O 3 P-Phen) 3 (1,10-phn)](HOiPr) (PTC-39), [Ti 4 (μ 3 -O)(μ 2 -OiPr) 3 (OiPr) 5 (O 3 P-Phen) 3 (Im)] (PTC-40), [Ti 4 (μ 3 -O)(μ 2 -OiPr) 3 (OiPr) 5 (O 3 P-Phen) 3 (Im)][Ti 3 M(μ 3 -O)(μ 2 -OiPr) 3 (OiPr) 3 (O 3 P-Phen) 3 (Im)] (M = Co for PTC-41 and M = Zn for PTC-42; O 3 P-Phen = phenyl phosphonate, 1-hbta = 1-hydroxy benzotriazolate, adn = adenine, 1,10-phn = 1,10-phenanthroline, Im = imidazolate, and OiPr = isopropoxide) were prepared as crystalline samples and structurally characterized. Simultaneous doping of nitrogen and transition metal heteroatoms into the Ti-O clusters created complex chemical environments in the resulting hybrid materials. Thus, photocatalytic methylene blue degradation studies were performed to understand structure-property relationships in these Ti cluster-based materials. The complex chemical environment created in these novel molecular clusters had proved to exhibit ligand-dependent photocatalytic activities under normal sunlight. Adenine-functionalized PTC-38 presented moderate activities, while other PTCs all show rapid dye degradation.

The effect of oral preexposure prophylaxis on the progression of HIV-1 seroconversion

PubMed Central

Donnell, Deborah; Ramos, Eric; Celum, Connie; Baeten, Jared; Dragavon, Joan; Tappero, Jordan; Lingappa, Jairam R.; Ronald, Allan; Fife, Kenneth; Coombs, Robert W.

2017-01-01

Objective: To investigate whether oral preexposure prophylaxis (PrEP) alters timing and patterns of seroconversion when PrEP use continues after HIV-1 infection. Design: Retrospective testing of the timing of Fiebig stage HIV-1 seroconversion in the Partners PrEP Study, a randomized placebo-controlled clinical trial of PrEP conducted in Kenya and Uganda. Methods: Specimens from 138 seroconverters were collected every 3 months and when HIV-1 infection was suspected based on monthly rapid HIV-1 tests. Progression of seroconversion was compared between randomized groups (PrEP versus placebo) and per-protocol groups (placebo versus PrEP participants with detectable tenofovir during the seroconversion period) using laboratory assessment of Fiebig stage. Delay in site-detection of seroconversion and association with PrEP drug-regimen resistant virus were assessed using logistic regression. Analysis of time to each Fiebig stage used maximum likelihood estimation with a parametric model to accommodate the varying lengths of HIV-infection intervals. Results: There was a significant increase in delayed site detection of infection associated with PrEP (odds ratio = 3.49, P = 0.044). Delay in detection was not associated with increased risk of resistance in the PrEP arm (odds ratio = 0.93, P = 0.95). Estimated time to each Fiebig stage was elongated in seroconverters with evidence of ongoing PrEP use, significantly for only Stage 5 (28 versus 17 days, P = 0.05). Adjusted for Fiebig stage, viral RNA was ∼2/3 log lower in those assigned to PrEP compared with placebo; no differences were found in Architect signal to cut-off at any stage. Conclusion: Ongoing PrEP use in seroconverters may delay detection of infection and elongate seroconversion, although the delay does not increase risk of resistance. PMID:28692542

Acceptability of HIV Pre-Exposure Prophylaxis (PrEP) and Implementation Challenges Among Men Who Have Sex with Men in India: A Qualitative Investigation.

PubMed

Chakrapani, Venkatesan; Newman, Peter A; Shunmugam, Murali; Mengle, Shruta; Varghese, Jarvis; Nelson, Ruban; Bharat, Shalini

2015-10-01

This qualitative study explored the acceptability of HIV pre-exposure prophylaxis (PrEP) among MSM in India, and identified facilitators and barriers to future PrEP uptake. In 2014, we conducted 10 focus groups (n=61) among a purposive sample of diverse MSM recruited through community-based organizations in Chennai and Mumbai, and 10 key informant interviews with community leaders and health care providers. Participants' mean age was 26.1 years (SD 4.8); 62% completed secondary education, and 42% engaged in sex work. No focus group participants had heard of PrEP, but once explained, most reported they would likely use it. PrEP was alternately perceived as a 'back-up plan', a condom substitute, or a burden with concurrent condom use. Facilitators were potential for covert use, sex without condoms, and anxiety-less sex. Potential barriers emerged around stigma associated with PrEP use, fear of disclosures to one's family, wife, or male steady partner, and being labeled as HIV-positive or promiscuous by peers. Preferences emerged for intermittent rather than daily PrEP use, injectable PrEP, and free or subsidized access through community organizations or government hospitals. Key informants expressed additional concerns about risk compensation, non-adherence, and impact on ART availability for treatment. Demonstration projects are needed in India to support PrEP implementation tailored for at-risk MSM. Educational interventions for MSM should address concerns about PrEP effectiveness, side effects, and mitigate risk compensation. Community engagement may facilitate broad acceptability and challenge stigma around PrEP use. Importantly, provision of free or subsidized PrEP is necessary to making implementation feasible among low socioeconomic status MSM in India.

Willingness to Use Pre-Exposure Prophylaxis (PrEP): An Empirical Test of the Information-Motivation-Behavioral Skills (IMB) Model among High-Risk Drug Users in Treatment.

PubMed

Shrestha, Roman; Altice, Frederick L; Huedo-Medina, Tania B; Karki, Pramila; Copenhaver, Michael

2017-05-01

Evidence from recent pre-exposure prophylaxis (PrEP) trials has demonstrated its safety and efficacy in significantly reducing the risk of HIV acquisition for those who are at considerable risk of acquiring HIV infection. With a rapid increase in the amount of research on the efficacy of PrEP for HIV prevention, complementary research on the willingness to use PrEP has grown, especially among MSM, but limited research has been focused among people who use drugs (PWUD). As part of the formative process, we utilized the information-motivation-behavioral skills (IMB) model of health behavior change to characterize and guide intervention development for promoting willingness to use PrEP among high-risk PWUD. The analysis included 400 HIV-negative high-risk PWUD enrolled in a community-based methadone maintenance treatment who reported drug- and/or sex-related HIV risk behaviors in the past 6-months. Analyses revealed support for the IMB model as PrEP-related behavioral skills were found to mediate the influence of PrEP-related information and motivation on willingness to use PrEP. The results provide evidence as to the utility of the IMB model to increase willingness to use PrEP among high-risk PWUD. It therefore makes an important contribution to our understanding of the applicability of theoretically-grounded models of willingness to use PrEP among high-risk PWUD, who are one of the key risk populations who could benefit from the use of PrEP.

Willingness to Use Pre-Exposure Prophylaxis (PrEP): An Empirical Test of the Information-Motivation-Behavioral Skills (IMB) Model among High-Risk Drug Users in Treatment

PubMed Central

Shrestha, Roman; Altice, Frederick L.; Huedo-Medina, Tania B.; Karki, Pramila; Copenhaver, Michael

2016-01-01

Evidence from recent pre-exposure prophylaxis (PrEP) trials has demonstrated its safety and efficacy in significantly reducing the risk of HIV acquisition for those who are at considerable risk of acquiring HIV infection. With a rapid increase in the amount of research on the efficacy of PrEP for HIV prevention, complementary research on the willingness to use PrEP has grown, especially among MSM, but limited research has been focused among people who use drugs (PWUD). As part of the formative process, we utilized the Information-Motivation-Behavioral Skills (IMB) model of health behavior change to characterize and guide intervention development for promoting willingness to use PrEP among high-risk PWUD. The analysis included 400 HIV-negative high-risk PWUD enrolled in a community-based methadone maintenance treatment who reported drug- and/or sex-related HIV risk behaviors in the past 6-months. Analyses revealed support for the IMB model as PrEP-related behavioral skills were found to mediate the influence of PrEP-related information and motivation on willingness to use PrEP. The results provide evidence as to the utility of the IMB model to increase willingness to use PrEP among high-risk PWUD. It therefore makes an important contribution to our understanding of the applicability of theoretically-grounded models of willingness to use PrEP among high-risk PWUD, who are one of the key risk populations who could benefit from the use of PrEP. PMID:27990587

Production of single-round infectious chimeric flaviviruses with DNA-based Japanese encephalitis virus replicon.

PubMed

Suzuki, Ryosuke; Ishikawa, Tomohiro; Konishi, Eiji; Matsuda, Mami; Watashi, Koichi; Aizaki, Hideki; Takasaki, Tomohiko; Wakita, Takaji

2014-01-01

A method for rapid production of single-round infectious particles (SRIPs) of flavivirus would be useful for viral mutagenesis studies. Here, we established a DNA-based production system for SRIPs of flavivirus. We constructed a Japanese encephalitis virus (JEV) subgenomic replicon plasmid, which lacked the C-prM-E (capsid-pre-membrane-envelope) coding region, under the control of the cytomegalovirus promoter. When the JEV replicon plasmid was transiently co-transfected with a JEV C-prM-E expression plasmid into 293T cells, SRIPs were produced, indicating successful trans-complementation with JEV structural proteins. Equivalent production levels were observed when C and prM-E proteins were provided separately. Furthermore, dengue types 1-4, West Nile, yellow fever or tick-borne encephalitis virus prM-E proteins could be utilized for production of chimaeric flavivirus SRIPs, although the production was less efficient for dengue and yellow fever viruses. These results indicated that our plasmid-based system is suitable for investigating the life cycles of flaviviruses, diagnostic applications and development of safer vaccine candidates.

Processing and nanostructure influences on mechanical properties of thermoelectric materials

NASA Astrophysics Data System (ADS)

Schmidt, Robert David

Thermoelectric (TE) materials are materials that can generate an electric current from a thermal gradient, with possible service in recovery of waste heat such as engine exhaust. Significant progress has been made in improving TE conversion efficiency, typically reported according to the figure of merit, ZT, with several recent papers publishing ZT values above 2. Furthermore, cost reductions may be made by the use of lower cost elements such as Mg, Si, Sn, Pb, Se and S in TE materials, while achieving ZT values between 1.3 and 1.8. To be used in a device, the thermoelectric material must be able to withstand the applied thermal and mechanical forces without failure. However, these materials are brittle, with low fracture toughness typically less than 1.5 MPa-m1/2, and often less than 0.5 MPa-m1/2. For comparison, window glass is approximately 0.75 MPa-m1/2. They have been optimized with nanoprecipitates, nanoparticles, doping, alterations in stoichiometry, powder processing and other techniques, all of which may alter the mechanical properties. In this study, the effect of SiC nanoparticle additions in Mg2Si, SnTe and Ag nanoparticle additions in the skutterudite Ba0.3Co 4Sb12 on the elastic moduli, hardness and fracture toughness are measured. Large changes (˜20%) in the elastic moduli in SnTe 1+x as a function of x at 0 and 0.016 are shown. The effect on mechanical properties of doping and precipitates of CdS or ZnS in a PbS or PbSe matrix have been reported. Changes in sintering behavior of the skutterudite with the Ag nanoparticle additions were explored. Possible liquid phase sintering, with associated benefits in lower processing temperature, faster densification and lower cost, has been shown. A technique has been proposed for determining additional liquid phase sintering aids in other TE materials. The effects of porosity, grain size, powder processing method, and sintering method were explored with YbAl3 and Ba0.3Co4Sb 12, with the porosity dependence of the elastic moduli reported. Only one other TE material has the porosity dependence of the elastic moduli previously reported in the literature, lead-antimony-silver-tellurium (LAST), and the effect of different powder processing and sintering methods has never been reported previously on TE materials.

Tracking Progesterone Receptor-Mediated Actions in Breast Cancer

PubMed Central

Knutson, Todd P.; Lange, Carol A.

2014-01-01

Ovarian steroid hormones contribute to breast cancer initiation and progression primarily through the actions of their nuclear transcription factors, the estrogen receptor alpha (ERα) and progesterone receptors (PRs). These receptors are important drivers of the luminal A and B subtypes of breast cancer, where estrogen-blocking drugs have been effective endocrine therapies for patients with these tumors. However, many patients do not respond, or become resistant to treatment. When endocrine therapies fail, the luminal subtypes of breast cancer are more difficult to treat because these subtypes are among the most heterogeneous in terms of mutation diversity and gene expression profiles. Recent evidence suggests that progestin and PR actions may be important drivers of luminal breast cancers. Clinical trial data has demonstrated that hormone replacement therapy with progestins drives invasive breast cancer and results in greater mortality. PR transcriptional activity is dependent upon cross-talk with growth factor signaling pathways that alter PR phosphorylation, acetylation, or SUMOylation as mechanisms for regulating PR target gene selection required for increased cell proliferation and survival. Site-specific PR phosphorylation is the primary driver of gene-selective PR transcriptional activity. However, PR phosphorylation and heightened transcriptional activity is coupled to rapid PR protein degradation; the range of active PR detected in tumors is likely to be dynamic. Thus, PR target gene signatures may provide a more accurate means of tracking PR’s contribution to tumor progression rather than standard clinical protein-based (IHC) assays. Further development of antiprogestin therapies should be considered along side antiestrogens and aromatase inhibitors. PMID:24291072

Occupations associated with COPD risk in the large population-based UK Biobank cohort study.

PubMed

De Matteis, Sara; Jarvis, Deborah; Hutchings, Sally; Darnton, Andy; Fishwick, David; Sadhra, Steven; Rushton, Lesley; Cullinan, Paul

2016-06-01

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Exposure to occupational hazards is an important preventable risk factor but the contribution of specific occupations to COPD risk in a general population is uncertain. Our aim was to investigate the association of COPD with occupation in the UK population. In 2006-2010, the UK Biobank cohort recruited 502 649 adults aged 40-69 years. COPD cases were identified by prebronchodilator forced expiratory volume in 1 s/forced vital capacity

Dynamic compressive behavior of Pr-Nd alloy at high strain rates and temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Huanran; Cai Canyuan; Chen Danian

2012-07-01

Based on compressive tests, static on 810 material test system and dynamic on the first compressive loading in split Hopkinson pressure bar (SHPB) tests for Pr-Nd alloy cylinder specimens at high strain rates and temperatures, this study determined a J-C type [G. R. Johnson and W. H. Cook, in Proceedings of Seventh International Symposium on Ballistics (The Hague, The Netherlands, 1983), pp. 541-547] compressive constitutive equation of Pr-Nd alloy. It was recorded by a high speed camera that the Pr-Nd alloy cylinder specimens fractured during the first compressive loading in SHPB tests at high strain rates and temperatures. From highmore » speed camera images, the critical strains of the dynamic shearing instability for Pr-Nd alloy in SHPB tests were determined, which were consistent with that estimated by using Batra and Wei's dynamic shearing instability criterion [R. C. Batra and Z. G. Wei, Int. J. Impact Eng. 34, 448 (2007)] and the determined compressive constitutive equation of Pr-Nd alloy. The transmitted and reflected pulses of SHPB tests for Pr-Nd alloy cylinder specimens computed with the determined compressive constitutive equation of Pr-Nd alloy and Batra and Wei's dynamic shearing instability criterion could be consistent with the experimental data. The fractured Pr-Nd alloy cylinder specimens of compressive tests were investigated by using 3D supper depth digital microscope and scanning electron microscope.« less

Investigation of Hill's optical turbulence model by means of direct numerical simulation.

PubMed

Muschinski, Andreas; de Bruyn Kops, Stephen M

2015-12-01

For almost four decades, Hill's "Model 4" [J. Fluid Mech. 88, 541 (1978) has played a central role in research and technology of optical turbulence. Based on Batchelor's generalized Obukhov-Corrsin theory of scalar turbulence, Hill's model predicts the dimensionless function h(κl(0), Pr) that appears in Tatarskii's well-known equation for the 3D refractive-index spectrum in the case of homogeneous and isotropic turbulence, Φn(κ)=0.033C2(n)κ(-11/3) h(κl(0), Pr). Here we investigate Hill's model by comparing numerical solutions of Hill's differential equation with scalar spectra estimated from direct numerical simulation (DNS) output data. Our DNS solves the Navier-Stokes equation for the 3D velocity field and the transport equation for the scalar field on a numerical grid containing 4096(3) grid points. Two independent DNS runs are analyzed: one with the Prandtl number Pr=0.7 and a second run with Pr=1.0 . We find very good agreement between h(κl(0), Pr) estimated from the DNS output data and h(κl(0), Pr) predicted by the Hill model. We find that the height of the Hill bump is 1.79 Pr(1/3), implying that there is no bump if Pr<0.17 . Both the DNS and the Hill model predict that the viscous-diffusive "tail" of h(κl(0), Pr) is exponential, not Gaussian.

An Evidence-Based Cue-Selection Guide and Logic Model to Improve Pressure Ulcer Prevention in Long Term Care

PubMed Central

Yap, Tracey L.; Kennerly, Susan M.; Bergstrom, Nancy; Hudak, Sandra L.; Horn, Susan D.

2015-01-01

Pressure ulcers (PrUs) have consistently resisted prevention efforts in long term care (LTC) facilities nationwide. Recent research has described cueing innovations that – when selected according to the assumptions and resources of particular facilities – support best practices of PrU prevention. This paper synthesizes that research into a unified, dynamic logic model to facilitate effective staff implementation of a PrU prevention program. PMID:26066791

Talking About The Smokes: a large-scale, community-based participatory research project.

PubMed

Couzos, Sophia; Nicholson, Anna K; Hunt, Jennifer M; Davey, Maureen E; May, Josephine K; Bennet, Pele T; Westphal, Darren W; Thomas, David P

2015-06-01

To describe the Talking About The Smokes (TATS) project according to the World Health Organization guiding principles for conducting community-based participatory research (PR) involving indigenous peoples, to assist others planning large-scale PR projects. The TATS project was initiated in Australia in 2010 as part of the International Tobacco Control Policy Evaluation Project, and surveyed a representative sample of 2522 Aboriginal and Torres Strait Islander adults to assess the impact of tobacco control policies. The PR process of the TATS project, which aimed to build partnerships to create equitable conditions for knowledge production, was mapped and summarised onto a framework adapted from the WHO principles. Processes describing consultation and approval, partnerships and research agreements, communication, funding, ethics and consent, data and benefits of the research. The TATS project involved baseline and follow-up surveys conducted in 34 Aboriginal community-controlled health services and one Torres Strait community. Consistent with the WHO PR principles, the TATS project built on community priorities and strengths through strategic partnerships from project inception, and demonstrated the value of research agreements and trusting relationships to foster shared decision making, capacity building and a commitment to Indigenous data ownership. Community-based PR methodology, by definition, needs adaptation to local settings and priorities. The TATS project demonstrates that large-scale research can be participatory, with strong Indigenous community engagement and benefits.

Screening of HIV-1 Protease Using a Combination of an Ultra-High-Throughput Fluorescent-Based Assay and RapidFire Mass Spectrometry.

PubMed

Meng, Juncai; Lai, Ming-Tain; Munshi, Vandna; Grobler, Jay; McCauley, John; Zuck, Paul; Johnson, Eric N; Uebele, Victor N; Hermes, Jeffrey D; Adam, Gregory C

2015-06-01

HIV-1 protease (PR) represents one of the primary targets for developing antiviral agents for the treatment of HIV-infected patients. To identify novel PR inhibitors, a label-free, high-throughput mass spectrometry (HTMS) assay was developed using the RapidFire platform and applied as an orthogonal assay to confirm hits identified in a fluorescence resonance energy transfer (FRET)-based primary screen of > 1 million compounds. For substrate selection, a panel of peptide substrates derived from natural processing sites for PR was evaluated on the RapidFire platform. As a result, KVSLNFPIL, a new substrate measured to have a ~ 20- and 60-fold improvement in k cat/K m over the frequently used sequences SQNYPIVQ and SQNYPIV, respectively, was identified for the HTMS screen. About 17% of hits from the FRET-based primary screen were confirmed in the HTMS confirmatory assay including all 304 known PR inhibitors in the set, demonstrating that the HTMS assay is effective at triaging false-positives while capturing true hits. Hence, with a sampling rate of ~7 s per well, the RapidFire HTMS assay enables the high-throughput evaluation of peptide substrates and functions as an efficient tool for hits triage in the discovery of novel PR inhibitors. © 2015 Society for Laboratory Automation and Screening.

Ex vivo mammalian prions are formed of paired double helical prion protein fibrils.

PubMed

Terry, Cassandra; Wenborn, Adam; Gros, Nathalie; Sells, Jessica; Joiner, Susan; Hosszu, Laszlo L P; Tattum, M Howard; Panico, Silvia; Clare, Daniel K; Collinge, John; Saibil, Helen R; Wadsworth, Jonathan D F

2016-05-01

Mammalian prions are hypothesized to be fibrillar or amyloid forms of prion protein (PrP), but structures observed to date have not been definitively correlated with infectivity and the three-dimensional structure of infectious prions has remained obscure. Recently, we developed novel methods to obtain exceptionally pure preparations of prions from mouse brain and showed that pathogenic PrP in these high-titre preparations is assembled into rod-like assemblies. Here, we have used precise cell culture-based prion infectivity assays to define the physical relationship between the PrP rods and prion infectivity and have used electron tomography to define their architecture. We show that infectious PrP rods isolated from multiple prion strains have a common hierarchical assembly comprising twisted pairs of short fibres with repeating substructure. The architecture of the PrP rods provides a new structural basis for understanding prion infectivity and can explain the inability to systematically generate high-titre synthetic prions from recombinant PrP. © 2016 The Authors.

Decision support tools for proton therapy ePR: intelligent treatment planning navigator and radiation toxicity tool for evaluating of prostate cancer treatment

NASA Astrophysics Data System (ADS)

Le, Anh H.; Deshpande, Ruchi; Liu, Brent J.

2010-03-01

The electronic patient record (ePR) has been developed for prostate cancer patients treated with proton therapy. The ePR has functionality to accept digital input from patient data, perform outcome analysis and patient and physician profiling, provide clinical decision support and suggest courses of treatment, and distribute information across different platforms and health information systems. In previous years, we have presented the infrastructure of a medical imaging informatics based ePR for PT with functionality to accept digital patient information and distribute this information across geographical location using Internet protocol. In this paper, we present the ePR decision support tools which utilize the imaging processing tools and data collected in the ePR. The two decision support tools including the treatment plan navigator and radiation toxicity tool are presented to evaluate prostate cancer treatment to improve proton therapy operation and improve treatment outcomes analysis.

Adherence to antiretroviral prophylaxis for HIV prevention: a substudy cohort within a clinical trial of serodiscordant couples in East Africa.

PubMed

Haberer, Jessica E; Baeten, Jared M; Campbell, James; Wangisi, Jonathan; Katabira, Elly; Ronald, Allan; Tumwesigye, Elioda; Psaros, Christina; Safren, Steven A; Ware, Norma C; Thomas, Katherine K; Donnell, Deborah; Krows, Meighan; Kidoguchi, Lara; Celum, Connie; Bangsberg, David R

2013-01-01

Randomized clinical trials of oral antiretroviral pre-exposure prophylaxis (PrEP) for HIV prevention have widely divergent efficacy estimates, ranging from 0% to 75%. These discrepancies are likely due to differences in adherence. To our knowledge, no studies to date have examined the impact of improving adherence through monitoring and/or intervention, which may increase PrEP efficacy, or reported on objective behavioral measures of adherence, which can inform PrEP effectiveness and implementation. Within the Partners PrEP Study (a randomized placebo-controlled trial of oral tenofovir and emtricitabine/tenofovir among HIV-uninfected members of serodiscordant couples in Kenya and Uganda), we collected objective measures of PrEP adherence using unannounced home-based pill counts and electronic pill bottle monitoring. Participants received individual and couples-based adherence counseling at PrEP initiation and throughout the study; counseling was intensified if unannounced pill count adherence fell to <80%. Participants were followed monthly to provide study medication, adherence counseling, and HIV testing. A total of 1,147 HIV-uninfected participants were enrolled: 53% were male, median age was 34 years, and median partnership duration was 8.5 years. Fourteen HIV infections occurred among adherence study participants--all of whom were assigned to placebo (PrEP efficacy = 100%, 95% confidence interval 83.7%-100%, p<0.001). Median adherence was 99.1% (interquartile range [IQR] 96.9%-100%) by unannounced pill counts and 97.2% (90.6%-100%) by electronic monitoring over 807 person-years. Report of no sex or sex with another person besides the study partner, younger age, and heavy alcohol use were associated with <80% adherence; the first 6 months of PrEP use and polygamous marriage were associated with >80% adherence. Study limitations include potential shortcomings of the adherence measures and use of a convenience sample within the substudy cohort. The high PrEP adherence achieved in the setting of active adherence monitoring and counseling support was associated with a high degree of protection from HIV acquisition by the HIV-uninfected partner in heterosexual serodiscordant couples. Low PrEP adherence was associated with sexual behavior, alcohol use, younger age, and length of PrEP use. Please see later in the article for the Editors' Summary.

Willingness to use pre-exposure prophylaxis (PrEP) for HIV prevention among men who have sex with men (MSM) in Malaysia: findings from a qualitative study

PubMed Central

Bourne, Adam; Cassolato, Matteo; Thuan Wei, Clayton Koh; Wang, Bangyuan; Pang, Joselyn; Lim, Sin How; Azwa, Iskandar; Yee, Ilias; Mburu, Gitau

2017-01-01

Abstract Background: Men who have sex with men (MSM) continue to be disproportionately affected by HIV in Malaysia. Recent success has been observed within demonstration projects examining the efficacy of HIV pre-exposure prophylaxis (PrEP), an antiretroviral -based medication taken by HIV-negative men to prevent sero-conversion. In order for such promising findings to be translated in real-world settings, it is important to understand the acceptability of PrEP, including perceived barriers to access or uptake. Methods: As part of a larger mixed-methods study exploring acceptability and willingness to use PrEP among MSM in Malaysia, 19 men took part in audio-recorded focus group discussions hosted by a community-based HIV organization and facilitated by a trained researcher. Discussions focussed on awareness and potential information management, general perceptions of PrEP and potential motivations or barriers to the use of PrEP, including those at the personal, social, health system or structural level. Data were transcribed verbatim and underwent a detailed thematic analysis. Results: Rather than perceiving PrEP as a replacement for condoms in terms of having safer sex, many participants viewed it as an additional layer protection, serving as a crucial barrier to infection on occasions where condom use was intended, but did not occur. It was also perceived as more valuable to “at-risk” men, such as those in HIV sero-discordant relationships or those with a higher number of sexual partners. Elements of discussion tended to suggest that some men taking PrEP may be subject to stigma from others, on the assumption they may be promiscuous or engage in high-risk sexual behaviours. Conclusions: This qualitative study indicates that, broadly speaking, PrEP may be acceptable to MSM in Malaysia. However, in order for its potential to be realized, and uptake achieved, educative interventions are required to inform the target population as to the efficacy and potential, positive impact of PrEP. Given concerns for how those taking it may be stigmatized, it is crucial that the use of PrEP is presented as a responsible course of action, and one of a range of strategies that men can use to keep themselves safe from HIV. PMID:28782336

Willingness to use pre-exposure prophylaxis (PrEP) for HIV prevention among men who have sex with men (MSM) in Malaysia: findings from a qualitative study.

PubMed

Bourne, Adam; Cassolato, Matteo; Thuan Wei, Clayton Koh; Wang, Bangyuan; Pang, Joselyn; Lim, Sin How; Azwa, Iskandar; Yee, Ilias; Mburu, Gitau

2017-08-02

Men who have sex with men (MSM) continue to be disproportionately affected by HIV in Malaysia. Recent success has been observed within demonstration projects examining the efficacy of HIV pre-exposure prophylaxis (PrEP), an antiretroviral -based medication taken by HIV-negative men to prevent sero-conversion. In order for such promising findings to be translated in real-world settings, it is important to understand the acceptability of PrEP, including perceived barriers to access or uptake. As part of a larger mixed-methods study exploring acceptability and willingness to use PrEP among MSM in Malaysia, 19 men took part in audio-recorded focus group discussions hosted by a community-based HIV organization and facilitated by a trained researcher. Discussions focussed on awareness and potential information management, general perceptions of PrEP and potential motivations or barriers to the use of PrEP, including those at the personal, social, health system or structural level. Data were transcribed verbatim and underwent a detailed thematic analysis. Rather than perceiving PrEP as a replacement for condoms in terms of having safer sex, many participants viewed it as an additional layer protection, serving as a crucial barrier to infection on occasions where condom use was intended, but did not occur. It was also perceived as more valuable to "at-risk" men, such as those in HIV sero-discordant relationships or those with a higher number of sexual partners. Elements of discussion tended to suggest that some men taking PrEP may be subject to stigma from others, on the assumption they may be promiscuous or engage in high-risk sexual behaviours. This qualitative study indicates that, broadly speaking, PrEP may be acceptable to MSM in Malaysia. However, in order for its potential to be realized, and uptake achieved, educative interventions are required to inform the target population as to the efficacy and potential, positive impact of PrEP. Given concerns for how those taking it may be stigmatized, it is crucial that the use of PrEP is presented as a responsible course of action, and one of a range of strategies that men can use to keep themselves safe from HIV.

Analysis of the costs and cost-effectiveness of the guidelines recommended by the 2018 GESIDA/Spanish National AIDS Plan for initial antiretroviral therapy in HIV-infected adults.

PubMed

Pérez-Molina, José Antonio; Martínez, Esteban; Blasco, Antonio Javier; Arribas, José Ramón; Domingo, Pere; Iribarren, José Antonio; Knobel, Hernando; Lázaro, Pablo; López-Aldeguer, José; Lozano, Fernando; Mariño, Ana; Miró, José M; Moreno, Santiago; Negredo, Eugenia; Pulido, Federico; Rubio, Rafael; Santos, Jesús; de la Torre, Javier; Tuset, Montserrat; von Wichmann, Miguel A; Gatell, Josep M

2018-06-05

The GESIDA/National AIDS Plan expert panel recommended preferred regimens (PR), alternative regimens (AR) and other regimens (OR) for antiretroviral treatment (ART) as initial therapy in HIV-infected patients for 2018. The objective of this study was to evaluate the costs and the efficiency of initiating treatment with PR and AR. Economic assessment of costs and efficiency (cost-effectiveness) based on decision tree analyses. Effectiveness was defined as the probability of reporting a viral load <50copies/mL at week 48, in an intention-to-treat analysis. Cost of initiating treatment with an ART regimen was defined as the costs of ART and its consequences (adverse effects, changes of ART regimen, and drug-resistance studies) over the first 48 weeks. The payer perspective (National Health System) was applied considering only differential direct costs: ART (official prices), management of adverse effects, studies of resistance, and HLA B*5701 testing. The setting was Spain and the costs correspond to those of 2018. A deterministic sensitivity analysis was conducted, building three scenarios for each regimen: base case, most favourable and least favourable. In the base-case scenario, the cost of initiating treatment ranges from 6788 euros for TAF/FTC/RPV (AR) to 10,649 euros for TAF/FTC+RAL (PR). The effectiveness varies from 0.82 for TAF/FTC+DRV/r (AR) to 0.91 for TAF/FTC+DTG (PR). The efficiency, in terms of cost-effectiveness, ranges from 7814 to 12,412 euros per responder at 48 weeks, for ABC/3TC/DTG (PR) and TAF/FTC+RAL (PR), respectively. Considering ART official prices, the most efficient regimen was ABC/3TC/DTG (PR), followed by TAF/FTC/RPV (AR) and TAF/FTC/EVG/COBI (AR). Copyright © 2018 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Dichloro-Cycloazatriphosphane: The Missing Link between N2 P2 and P4 Ring Systems in the Systematic Development of NP Chemistry.

PubMed

Bresien, Jonas; Hinz, Alexander; Schulz, Axel; Suhrbier, Tim; Thomas, Max; Villinger, Alexander

2017-10-20

A dichloro-cycloazatriphosphane that incorporates a cyclic NP 3 backbone could be synthesized using knowledge gained from the chemistry of N 2 P 2 and P 4 ring systems. It fills the gap between the congeneric compounds [ClP(μ-NR)] 2 and [ClP(μ-PR)] 2 (R=sterically demanding substituent), and thus contributes to the systematic development of nitrogen-phosphorus chemistry in general. The title compound was studied with respect to its formation via a labile aminodiphosphene, which readily underwent different rearrangement reactions depending on the solvent. All compounds were fully characterized by experimental and computational methods. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Engineering Human Immunodeficiency Virus 1 Protease Heterodimers as Macromolecular Inhibitors of Viral Maturation

NASA Astrophysics Data System (ADS)

McPhee, Fiona; Good, Andrew C.; Kuntz, Irwin D.; Craik, Charles S.

1996-10-01

Dimerization of human immunodeficiency virus type 1 protease (HIV-1 PR) monomers is an essential prerequisite for viral proteolytic activity and the subsequent generation of infectious virus particles. Disruption of the dimer interface inhibits this activity as does formation of heterodimers between wild-type and defective monomers. A structure-based approach was used to identify amino acid substitutions at the dimer interface of HIV-1 PR that facilitate preferential association of heterodimers and inhibit self-association of the defective monomers. Expression of the designed PR monomers inhibits activity of wild-type HIV-1 PR and viral infectivity when assayed in an ex vivo model system. These results show that it is possible to design PR monomers as macromolecular inhibitors that may provide an alternative to small molecule inhibitors for the treatment of HIV infection.

Science, technology, power and sex: PrEP and HIV-positive gay men in Paris.

PubMed

Brisson, Julien; Nguyen, Vinh-Kim

2017-10-01

The pre-exposure prophylaxis (PrEP) drug Truvada is a new HIV prevention technology that is predominantly promoted as relevant to HIV-negative gay men. This paper explores what PrEP represents for HIV-positive gay men living in Paris, based upon data collected through interviews and ethnographic research. While HIV-positive gay men do not directly consume Truvada through PrEP, they nonetheless hold opinions and understandings of this drug, specifically as it relates to their own sexuality. This paper expands the representations and meanings of this new technology in a different light through the voices of gay men living with HIV in Paris. The main argument of this article is that PrEP as an additional HIV prevention tool blurs the lines between science, technologies and human sexuality.

Defining success with HIV pre-exposure prophylaxis: A prevention-effective adherence paradigm

PubMed Central

Haberer, Jessica E.; Bangsberg, David R.; Baeten, Jared M.; Curran, Kathryn; Koechlin, Florence; Amico, K. Rivet; Anderson, Peter; Mugo, Nelly; Venter, Francois; Goicochea, Pedro; Caceres, Carlos; O’Reilly, Kevin

2015-01-01

Clinical trial data have shown that oral pre-exposure prophylaxis (PrEP) is efficacious when taken as prescribed; however, PrEP adherence is complex and must be understood within the context of variable risk for HIV infection and use of other HIV prevention methods. Different levels of adherence may be needed in different populations to achieve HIV prevention, and the optimal methods for achieving the necessary adherence for both individual and public health benefits are unknown. Guidance for PrEP use must consider these questions to determine the success of PrEP-based HIV prevention programs. In this article, we propose a new paradigm for understanding and measuring PrEP adherence, termed prevention-effective adherence, which incorporates dynamic HIV acquisition risk behaviors and the use of HIV alternative prevention strategies. We discuss the need for daily PrEP use only during periods of risk for HIV exposure, describe key issues for measuring and understanding relevant behaviors, review lessons from another health prevention field (i.e., family planning), and provide guidance for prevention-effective PrEP use. Moreover, we challenge emerging calls for sustained, near perfect PrEP adherence regardless of risk exposure and offer a more practical and public health-focused vision for this prevention intervention. PMID:26103095

PrEP as peri-conception HIV prevention for women and men

PubMed Central

Heffron, Renee; Pintye, Jillian; Matthews, Lynn T.; Weber, Shannon; Mugo, Nelly

2016-01-01

Daily oral tenofovir (TDF)-based pre-exposure prophylaxis (PrEP) is an effective HIV prevention strategy and recommended for men and women with substantial risk of HIV acquisition. The peri-conception period, the stage prior to pregnancy when condom use is necessarily reduced, has elevated HIV risk that can be mitigated by PrEP use. Data from a randomized trial suggest that peri-conception PrEP use by HIV-seronegative women does not increase the risk of pregnancy loss, birth defects or congenital anomalies, preterm birth, or infant growth faltering. Women considering PrEP use throughout pregnancy must weigh the known increased risk of HIV acquisition with unknown risks of drug effects on infant growth. PrEP has been used safely by HIV-seronegative men with HIV-seropositive female partners who have become pregnant. As an effective user-controlled HIV prevention strategy, PrEP offers autonomy and empowerment for HIV prevention and can be recommended alongside antiretroviral therapy, fertility screening, vaginal self-insemination, intercourse timed to peak fertility, medically assisted reproduction, and other safer conception strategies to provide multiple options. The integration of PrEP into safer conception programs is warranted and will safely reduce HIV transmission to women, men and children during the peri-conception period. PMID:26993627

Acceptability of PrEP among HIV negative Portuguese men who have sex with men that attended 2014 Lisbon pride fair.

PubMed

Rocha, Luís Miguel; Campos, Maria José; Brito, João; Fuertes, Ricardo; Rojas, Jesus; Pinto, Nuno; Mendão, Luís; Esteves, Julio

2014-01-01

Consistent use of PrEP reduces HIV transmission from sexual practices amongst men who have sex with men (MSM) up to 92% [1]. Lisbon MSM cohort study estimates point that 59.3% of their participants at entrance (1593 HIV negative MSM enrolled between April 2011 and May 2013) were eligible for PrEP [2], according to the 2014 USA PrEP guidelines [3]. Studies about PrEP acceptability and implementation support policies aimed at increasing and rolling out its use. Hence, the exploratory study about PrEP acceptability in MSM at Lisbon. A street-based intercept survey, adapted from Mantell et al. study [4], was the one used on MSM attending the 2014 Lisbon pride fair. The survey included socio-demographic data, PrEP awareness and readiness to use it, probability of MSM's social network to also use it, promptness to join PrEP-related studies, type of PrEP warranted and condomless anal sex practice in the last six months. A total of 110 HIV negative Portuguese MSM responded, with a median age of 33% and 84% of them identified themselves as gay. A majority of MSM were unaware of PrEP (59%); those that were aware, had heard of it trough CheckpointLx (31%), internet (22%) or health professionals (20%). 66% were likely or very likely to participate in PrEP-related studies. 57% of MSM were likely or very likely to use PrEP if available and reported that some, if not almost all of their social network, will do it too (70%). Type of PrEP preferred was oral, a pill a day (43%), followed by oral, intermittent intake (32%). Overall 41% of MSM had condomless anal sex practice in the last six months. In this MSM Portuguese sample, a general willingness to adopt PrEP was predominant, specially the oral daily intake. Forty-one percent of participants had had condomless anal sex practice in the last six months and therefore fitted within the criteria to be on Pre-Exposure Prophylaxis (PrEP), according to MSM Risk Index in 2014 USA PrEP guidelines. PrEP, when available in Portugal, should be a powerful tool for HIV prevention in this key population.

Implementation and Operational Research: A Cost-Effective, Clinically Actionable Strategy for Targeting HIV Preexposure Prophylaxis to High-Risk Men Who Have Sex With Men.

PubMed

Ross, Eric L; Cinti, Sandro K; Hutton, David W

2016-07-01

Preexposure prophylaxis (PrEP) is effective at preventing HIV infection among men who have sex with men (MSM), but there is uncertainty about how to identify high-risk MSM who should receive PrEP. We used a mathematical model to assess the cost-effectiveness of using the HIV Incidence Risk Index for MSM (HIRI-MSM) questionnaire to target PrEP to high-risk MSM. We simulated strategies of no PrEP, PrEP available to all MSM, and eligibility thresholds set to HIRI-MSM scores between 5 and 45, in increments of 5 (where a higher score predicts greater HIV risk). Based on the iPrEx, IPERGAY, and PROUD trials, we evaluated PrEP efficacies from 44% to 86% and annual costs from $5900 to 8700. We designate strategies with incremental cost-effectiveness ratio (ICER) ≤$100,000/quality-adjusted life-year (QALY) as "cost-effective." Over 20 years, making PrEP available to all MSM is projected to prevent 33.5% of new HIV infections, with an ICER of $1,474,000/QALY. Increasing the HIRI-MSM score threshold reduces the prevented infections, but improves cost-effectiveness. A threshold score of 25 is projected to be optimal (most QALYs gained while still being cost-effective) over a wide range of realistic PrEP efficacies and costs. At low cost and high efficacy (IPERGAY), thresholds of 15 or 20 are optimal across a range of other input assumptions; at high cost and low efficacy (iPrEx), 25 or 30 are generally optimal. The HIRI-MSM provides a clinically actionable means of guiding PrEP use. Using a score of 25 to determine PrEP eligibility could facilitate cost-effective use of PrEP among high-risk MSM who will benefit from it most.

Hydroxypropyl-β-CD vs. its α-homologue for a 3D modified polyrotaxane network formation and properties: the relationship between modified CD and polymer revealed through comparison.

PubMed

Li, Zhao; Zheng, Zhen; Su, Shan; Yu, Lin; Wang, Xinling

2016-09-14

The threading mechanism of the hydroxypropyl-cyclodextrin (Hy-CD)/tetrahedron-like poly(ethylene glycol) (tetra-PEG) based host-guest complex and the relationship between Hy-CD and poly(ethylene oxide) (PEO) in the three-dimensional modified polyrotaxane (PR) formed by the complex were revealed through the comparison between Hy-β-CD/tetra-PEG and Hy-α-CD/tetra-PEG based systems from the macroscopic material view to the microscopic molecular view. The complexation between Hy-CD and tetra-PEG in water experiences a threading-dethreading-rethreading process which is controlled by the intermolecular interaction intensity or molecular hindrance depending on the feed ratio of Hy-CD to tetra-PEG. In the 3D modified PR, the methyl group of the Hy part on one Hy-CD can insert into the cavity of the adjacent Hy-CD and interacts with both the interior surface of the cavity and the PEO segment within the cavity if the cavity of Hy-CD is large enough. The threaded Hy-CD in the PR straightens the chain of PEO and suppresses the segment motion of the PEO. With the decrease of the cavity size of Hy-CD, the degree of suppression on the segment motion of PEO increases. Hy-CD threaded on the PEO chain can also deform when the 3D modified PR is compressed, and the degree of deformation increases with the increase of the cavity size of Hy-CD. These results of the modified CD/PEG based complex system set it apart from the unmodified CD/PEG based one, and reveal the structure-property relationship of this new type of Hy-CD/tetra-PEG based 3D modified PR material.

Cost utility of telaprevir-PR (peginterferon-ribavirin) versus boceprevir-PR and versus PR alone in chronic hepatitis C in The Netherlands.

PubMed

Vellopoulou, Aikaterini; van Agthoven, Michel; van der Kolk, Annemarie; de Knegt, Robert J; Berdeaux, Gilles; Cure, Sandrine; Bianic, Florence; Lamotte, Mark

2014-12-01

The hepatitis C virus may lead to cirrhosis, liver cancer, liver transplant, and increased mortality. With standard treatment peginterferon-alpha and ribavirin (PR), sustained viral response (SVR) was less than 50 %. SVR rates improve greatly when PR is combined with telaprevir or boceprevir. The aim of this study was to assess the cost utility of telaprevir-peginterferon-ribavirin (TPR) versus PR and boceprevir-peginterferon-ribavirin (BPR) in treatment-naïve (TN) and treatment-experienced (TE) adults with chronic hepatitis C in the Netherlands. A Markov model with a lifelong time horizon and annual cycles was developed. Clinical data stemmed from phase III trials (TPR vs PR, BPR vs PR). A mixed treatment comparison (MTC) was developed to compare TPR and BPR indirectly. Unit costs and utilities based on EQ-5D were established in a Dutch cross-sectional study. Cost per quality-adjusted life-years (QALYs) was calculated according to the societal perspective. Treating TN patients with TPR generates 1.12 additional QALYs with €333 additional cost compared with PR, resulting in an incremental cost-utility ratio of €299/QALY. In TE patients, TPR dominates PR with cost savings (-€7,819) and 1.63 additional QALYs. TPR dominates BPR yielding additional QALYs (0.26 in TN; 0.71 in TE) and cost savings (-€7,296, -€18,144, respectively). TPR seems a cost-effective alternative to PR in TN patients and dominant in TE patients. TPR was a dominant, more effective and less costly alternative to BPR in both patient types. The cost effectiveness of both TPR and BPR is well below generally accepted willingness-to-pay thresholds and may be considered cost effective.

Values and Preferences on the Use of Oral Pre-exposure Prophylaxis (PrEP) for HIV Prevention Among Multiple Populations: A Systematic Review of the Literature.

PubMed

Koechlin, Florence M; Fonner, Virginia A; Dalglish, Sarah L; O'Reilly, Kevin R; Baggaley, Rachel; Grant, Robert M; Rodolph, Michelle; Hodges-Mameletzis, Ioannis; Kennedy, Caitlin E

2017-05-01

Daily oral pre-exposure prophylaxis (PrEP) is the use of antiretroviral drugs by HIV-negative people to prevent HIV infection. WHO released new guidelines in 2015 recommending PrEP for all populations at substantial risk of HIV infection. To prepare these guidelines, we conducted a systematic review of values and preferences among populations that might benefit from PrEP, women, heterosexual men, young women and adolescent girls, female sex workers, serodiscordant couples, transgender people and people who inject drugs, and among healthcare providers who may prescribe PrEP. A comprehensive search strategy reviewed three electronic databases of articles and HIV-related conference abstracts (January 1990-April 2015). Data abstraction used standardised forms to categorise by population groups and relevant themes. Of 3068 citations screened, 76 peer-reviewed articles and 28 conference abstracts were included. Geographic coverage was global. Most studies (N = 78) evaluated hypothetical use of PrEP, while 26 studies included individuals who actually took PrEP or placebo. Awareness of PrEP was low, but once participants were presented with information about PrEP, the majority said they would consider using it. Concerns about safety, side effects, cost and effectiveness were the most frequently cited barriers to use. There was little indication of risk compensation. Healthcare providers would consider prescribing PrEP, but need more information before doing so. Findings from a rapidly expanding evidence base suggest that the majority of populations most likely to benefit from PrEP feel positively towards it. These same populations would benefit from overcoming current implementation challenges with the shortest possible delay.

Supporting study product use and accuracy in self-report in the iPrEx study: next step counseling and neutral assessment.

PubMed

R Amico, K; McMahan, Vanessa; Goicochea, Pedro; Vargas, Lorena; Marcus, Julia L; Grant, Robert M; Liu, Albert

2012-07-01

The recent successes of biomedical HIV prevention approaches have sparked considerable debate over the scalability, feasibility, and acceptability of pre-exposure prophylaxis (PrEP) as a widespread prevention strategy for men who have sex with men and trans-gender. Anticipated difficulties with PrEP adherence and concerns about resources required to best support it have tempered enthusiasm of PrEP demonstration projects and roll-out. While no evidence-based approach for supporting PrEP use is presently available, a number of approaches have been developed in the context of double-blind, randomized, placebo-controlled trials of PrEP that can provide guidance in moving forward with real world support of open label PrEP use. We present the development, implementation and evaluation of feasibility and acceptability of next-step counseling (NSC) and neutral assessment (NA), the adherence support and promotion of accurate reporting approaches used in the late phases of the iPrEx study. Evaluation of the approach from the perspective of implementers of over 15,000 NSC sessions in seven different countries with almost 2,000 iPrEx participants provided support for NSC, its brevity (averaging ~14 min per follow-up session) and overall acceptability and feasibility. NA also was generally well supported, with a majority of study staff believing this approach was feasible and acceptable; however, lower acceptability for certain aspects of NA was noted amongst staff reporting NA was different from their previous interview approach. Quantitative and qualitative data gathered from implementers were used to make modifications for supporting PrEP use in the open-label extension of iPrEx.

Does Pre-exposure prophylaxis (PrEP) for HIV prevention in men who have sex with men (MSM) change risk behavior? A systematic review.

PubMed

Freeborn, Kellie; Portillo, Carmen J

2017-08-03

Pre-exposure prophylaxis (PrEP) for HIV has been available since 2012. Even so, PrEP has not been widely accepted among healthcare providers and MSM some of whom are convinced that PrEP decreases condom use, and increases sexually transmitted infections (STIs). A systematic review of the state of the evidence regarding the association of PrEP with condom use, STI incidence and change in sexual risk behaviors in MSM. A structured search of databases resulted in 142 potential citations, but only ten publications met inclusion criteria and underwent data abstraction and critical appraisal. An adapted Cochrane Collaboration domain based assessment tool was used to critically appraise the methodological components of each quantitative study, and the Mixed Methods Appraisal Tool (MMAT) was used to critically appraise qualitative and mixed-methods studies. Condom use in MSM utilizing PrEP is influenced by multiple factors. Studies indicate rates of STIs in treatment and placebo groups were high. PrEP did not significantly change STI rates between baseline and follow-up. Reporting of sexual risk improved when questionnaires were completed in private by clients. Our review found that PrEP may provide an opportunity for MSM to access sexual health care, testing, treatment and counselling services. We did not find any conclusive evidence that PrEP users increase sexual risk behaviors. The perception among healthcare providers that PrEP leads to increased sexual risk behaviors has yet to be confirmed. In order to provide effective sexual health services, clinicians need to be knowledgeable about PrEP as an HIV prevention tool. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The Pre-Exposure Prophylaxis-Stigma Paradox: Learning from Canada's First Wave of PrEP Users.

PubMed

Grace, Daniel; Jollimore, Jody; MacPherson, Paul; Strang, Matthew J P; Tan, Darrell H S

2018-01-01

With the emergence of daily oral tenofovir disoproxil fumarate and emtricitabine-based pre-exposure prophylaxis (PrEP) use in Canada, questions have emerged concerning the impacts of this HIV prevention tool on gay men's social and sexual lives. We conducted small focus groups and individual qualitative interviews with 16 gay men in Toronto who were part of the 'first wave' of Canadian PrEP users. Participants were on PrEP for at least one year as part of a demonstration project (November 2014-June 2016). These participants accessed PrEP before regulatory approval by Health Canada in February 2016. The mean age of participants was 37.6 years (SD 11.02); 94% completed secondary education, and 69% were white. Sex-stigma emerged as a complex theme in men's accounts of PrEP use across three overlapping domains: (1) PrEP-related stigma, including discussions of concealment and stigma from friends, family, and sexual partners, (2) PrEP as a perceived tool for combating HIV-related stigma, where some men said that they no longer discussed HIV status with sexual partners, and (3) PrEP as illuminating structural stigma, where it was attributed to unmasking stigma related to sex and sexuality. For some participants, PrEP has allowed for liberating sex and a self-described return to normalcy-normal, exciting, pleasurable sex that was no longer reliant on condom use. Paradoxically, some men said that PrEP use both led them to experience stigmatizing reactions within their social and sexual networks, while also helping to remove stigma, shame, and fear related to HIV, sexuality, and sex with gay men living with HIV.

Risk factors and acute in-hospital costs for infected pressure ulcers among gunshot-spinal cord injury victims in southeastern Michigan.

PubMed

Chopra, Teena; Marchaim, Dror; Awali, Reda A; Levine, Miriam; Sathyaprakash, Smitha; Chalana, Indu K; Ahmed, Farah; Martin, Emily T; Sieggreen, Mary; Sobel, Jack D; Kaye, Keith S

2016-03-01

Management of pressure ulcers (PrUs) in patients with gunshot-spinal cord injuries (SCIs) presents unique medical and economic challenges for practitioners. A retrospective chart review was conducted at 3 acute care hospitals in metropolitan Detroit for patients admitted with PrUs due to gunshot-SCIs between January 2004 and December 2008. Multivariate analysis using logistic regression was conducted to choose for the independent predictors of infected PrUs. Mean adjusted in-hospital costs per patient and per hospitalization were calculated and compared between infected and noninfected PrUs. The study cohort included 201 gunshot-SCI patients with PrUs contributing to 395 admissions, including readmissions, between 2004 and 2008. Seventy-six patients (38%) had infected PrUs at time of the index admission. Independent predictors of infected PrUs on index admission included Charlson Comorbidity Index ≥2 (odds ratio, 2.18, P = .026) and stage III/IV PrU (odds ratio, 4.82; P <.0001). During the study period, the cumulative median duration of hospitalization per patient was 12 days (interquartile range, 6-24 days), resulting in a mean adjusted cost of $19,969 ± $6639 per patient. The mean adjusted cost per hospitalization for patients with infected PrUs was significantly higher than that for patients with noninfected PrUs ($16,735 ± $8310 vs $12,356 ± $7007; P <.001). A multidisciplinary approach including home-based rehabilitation programs and SCI wound clinics might help prevent PrUs and their complications and reduce associated costs. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

HIV pre-exposure prophylaxis: Exploring the potential for expanding the role of pharmacists in public health.

PubMed

Okoro, Olihe; Hillman, Lisa

2018-05-19

The study objectives were to a) assess knowledge and experience; b) describe perceptions and attitudes; and c) identify training needs of community-based pharmacists regarding HIV pre-exposure prophylaxis (PrEP). This was a cross-sectional survey study. The survey was administered online to pharmacists practicing in a community setting in the state of Minnesota. Measures included knowledge of and experience with HIV PrEP, perceptions and attitudes towards pharmacists' involvement, and HIV PrEP-specific training needs for pharmacists. With a survey response rate of approximately 13% (n = 347), most respondents (76.4%) agreed that HIV PrEP can be beneficial in high-risk populations. Forty-six percent of respondents were not aware of U.S. Food and Drug Administration approval of emtricitabine and tenofovir disoproxil fumarate for PrEP. Most respondents (71.1%) were "not at all familiar" with Centers for Disease Control and Prevention guidelines for PrEP. Twenty-one percent of respondents had sufficient knowledge to counsel patients on PrEP. Experience with counseling on PrEP (21.8%), having dispensed PrEP in the last 2 years (33.1%), fewer years in practice (≤10 years), location of practice site (urban or suburban), and having received HIV continuing education in the last 2 years (33.0%) were associated with more knowledge of HIV PrEP. Top concerns with counseling were knowledge about the medication and behavior modification. The most frequently indicated primary concerns with implementing PrEP initiatives were identifying appropriate candidates and patient adherence. As pharmacists' roles continue to expand, relevant content in pharmacy education and requisite training (including continuing education) are critical to addressing knowledge gaps and competencies that will enable pharmacists engage more effectively in public health efforts such as HIV prevention. Published by Elsevier Inc.

Light-Emitting Diodes Based on Colloidal Silicon Quantum Dots with Octyl and Phenylpropyl Ligands.

PubMed

Liu, Xiangkai; Zhao, Shuangyi; Gu, Wei; Zhang, Yuting; Qiao, Xvsheng; Ni, Zhenyi; Pi, Xiaodong; Yang, Deren

2018-02-14

Colloidal silicon quantum dots (Si QDs) hold ever-growing promise for the development of novel optoelectronic devices such as light-emitting diodes (LEDs). Although it has been proposed that ligands at the surface of colloidal Si QDs may significantly impact the performance of LEDs based on colloidal Si QDs, little systematic work has been carried out to compare the performance of LEDs that are fabricated using colloidal Si QDs with different ligands. Here, colloidal Si QDs with rather short octyl ligands (Octyl-Si QDs) and phenylpropyl ligands (PhPr-Si QDs) are employed for the fabrication of LEDs. It is found that the optical power density of PhPr-Si QD LEDs is larger than that of Octyl-Si QD LEDs. This is due to the fact that the surface of PhPr-Si QDs is more oxidized and less defective than that of Octyl-Si QDs. Moreover, the benzene rings of phenylpropyl ligands significantly enhance the electron transport of QD LEDs. It is interesting that the external quantum efficiency (EQE) of PhPr-Si QD LEDs is lower than that of Octyl-Si QD LEDs because the benzene rings of phenylpropyl ligands suppress the hole transport of QD LEDs. The unbalance between the electron and hole injection in PhPr-Si QD LEDs is more serious than that in Octyl-Si QD LEDs. The currently obtained highest optical power density of ∼0.64 mW/cm 2 from PhPr-Si QD LEDs and highest EQE of ∼6.2% from Octyl-Si QD LEDs should encourage efforts to further advance the development of high-performance optoelectronic devices based on colloidal Si QDs.

Antiretroviral-based HIV-1 Prevention: Antiretroviral Treatment and Pre-Exposure Prophylaxis

PubMed Central

Celum, Connie; Baeten, Jared

2012-01-01

Antiretroviral-based HIV-1 prevention strategies – including antiretroviral treatment (ART) to reduce the infectiousness of HIV-1 infected persons and oral and topical pre-exposure prophylaxis (PrEP) for uninfected persons to prevent HIV-1 acquisition – are the most promising new approaches for decreasing HIV-1 spread. Observational studies among HIV-1 serodiscordant couples have associated ART initiation with a reduction in HIV-1 transmission risk of 80–92%, and a recent randomized trial demonstrated that earlier initiation of ART (i.e., at CD4 counts between 350 and 550 cells/mm3), in the context of virologic monitoring and adherence support, resulted in a 96% reduction in HIV-1 transmission. A number of ongoing and recently-completed clinical trials have assessed the efficacy of PrEP for HIV-1 prevention as peri-coitally administered or daily-administered 1% tenofovir gel and daily oral tenofovir and combination emtricitabine/tenofovir. Completed studies have demonstrated HIV-1 protection efficacies ranging from 39% to 75%. However, two trials in African women have shown no HIV-1 protection with PrEP; the reasons for lack of efficacy in those trials are being investigated. Adherence is likely key to efficacy of antiretrovirals for HIV-1 prevention, both as ART and PrEP. Critical unanswered questions for successful delivery of antiretroviral-based HIV-1 prevention include how to target ART and PrEP to realize maximum population benefits, whether HIV-1 infected persons at earlier stages of infection would accept ART to reduce their risk for transmitting HIV-1 and highest-risk HIV-1 negative persons would use PrEP, and whether high adherence could be sustained to achieve high effectiveness. PMID:23221365

Efficacy of oral pre-exposure prophylaxis (PrEP) for HIV among women with abnormal vaginal microbiota: a post-hoc analysis of the randomised, placebo-controlled Partners PrEP Study.

PubMed

Heffron, Renee; McClelland, R Scott; Balkus, Jennifer E; Celum, Connie; Cohen, Craig R; Mugo, Nelly; Bukusi, Elizabeth; Donnell, Deborah; Lingappa, Jairam; Kiarie, James; Fiedler, Tina; Munch, Matthew; Fredricks, David N; Baeten, Jared M

2017-10-01

Daily oral tenofovir-based pre-exposure prophylaxis (PrEP) is high efficacious for HIV prevention among women with high adherence. However, the effect of abnormal vaginal microbiota on PrEP efficacy is of concern. We investigated whether bacterial vaginosis modified the efficacy of oral PrEP. We used prospectively collected data from women in the Partners PrEP Study, a placebo-controlled trial of daily oral PrEP (either tenofovir monotherapy or a combination of tenofovir and emtricitabine) in HIV serodiscordant couples aged 18 years or older in Kenya and Uganda that showed high efficacy in women. We used Cox proportional hazards regression to assess PrEP efficacy among subgroups of women defined by bacterial vaginosis status based on yearly microscopy and Nugent scoring (0-3 indicated healthy microbiota, 4-6 intermediate, and 7-10 bacterial vaginosis). In separate efficacy analyses, we also investigated individual components of the score (ie, detection of Gardnerella vaginalis or Bacteroides spp and non-detection of Lactobacillus spp) as markers of abnormal microbiota. Of 1470 women (median age 33 years), 357 (24%) had bacterial vaginosis at enrolment. 45 women seroconverted to HIV. The HIV prevention efficacy of PrEP did not differ significantly among women with healthy microbiota (incidence 0·6 per 100 person years in PrEP group and 2·5 per 100 person-years in the placebo group; efficacy 76·55% [95% CI 43·09 to 90·37]), intermediate microbiota (HIV incidence 1·8 per 100 person-years in the PrEP group and 3·5 per 100 person-years in the placebo group; efficacy 62·72% [95% CI -66·59 to 91·66]), or bacterial vaginosis (HIV incidence 0·9 per 100 person-years in the PrEP group and 3·5 per 100 person-years in the placebo group; efficacy 72·50% [95% CI 5·98 to 91·95]; p interaction =0·871). PrEP efficacy was not significantly different between women with detected G vaginalis or Bacteroides spp morphotypes and those without these morphotypes (efficacy 68·62% vs 76·72%; p interaction =0·652); or between those with Lactobacillus spp morphotypes and those without (70·48% vs 74·08%; p interaction =0·86). Among African women with a high prevalence of bacterial vaginosis and high adherence to PrEP, the efficacy of daily oral PrEP for HIV prevention did not differ significantly among women with abnormal versus healthy vaginal microbiota as defined by Nugent score. These data are reassuring that oral PrEP delivery to women can continue without the need for concurrent testing for bacterial vaginosis or vaginal dysbiosis. Bill & Melinda Gates Foundation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and National Institute of Allergy and Infectious Diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Overweight and obesity are not associated with dental caries among 12-year-old South Brazilian schoolchildren.

PubMed

Alves, Luana Severo; Susin, Cristiano; Damé-Teixeira, Nailê; Maltz, Marisa

2013-06-01

To assess the association between weight status and dental caries among 12-year-old Brazilian schoolchildren. This cross-sectional study was carried out in Porto Alegre using a multistage probability sampling strategy to draw a representative sample of schoolchildren attending public and private schools. Data on demographics, socioeconomic status, oral hygiene habits, anthropometrics, and dental caries were collected. Overweight and obesity were defined according to WHO categories for BMI (body mass index)-for-age Z-scores. Survey Poisson regression models were used to assess the association between weight status and dental caries. Estimates were adjusted for gender, socioeconomic status, and brushing frequency. Prevalence ratios (PR), rate ratios (RR) and 95% confidence intervals (95% CI) were reported. One thousand five hundred and twenty-eight of 1837 eligible schoolchildren were examined. Prevalence of overweight and obesity were 22.15% (95% CI = 20.59-23.72) and 13.61% (95% CI = 11.44-15.78), respectively. Caries experience was observed in 55.23% (95% CI = 45.26-65.19) of children. Schoolchildren presented, on average, 1.39 (95% CI = 1.07-1.71) decayed, missing or filled teeth. No significant differences in caries experience or extent were observed among BMI groups. After adjusting for important cofactors, weight status was not associated with caries prevalence (overweight, PR = 0.99; 95% CI = 0.89-1.10; obese, PR = 1.00; 95% CI = 0.87-1.16) or caries extent (overweight, RR = 0.91; 95% CI = 0.74-1.12; obese, RR = 0.86; 95% CI = 0.72-1.04). Our findings indicate that overweight and obese adolescents should not be regarded as at higher risk of dental caries in this population. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.

The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D 3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D 3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was usedmore » to infer the areal density (pR) and the shell center-of-mass radius (R cm) from the downshift of the shock-produced D 3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.« less

The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

DOE PAGES

Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; ...

2014-11-03

The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D 3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D 3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was usedmore » to infer the areal density (pR) and the shell center-of-mass radius (R cm) from the downshift of the shock-produced D 3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.« less

The formation, structure and physical properties of M(2)Pd(14+x)B(5-y) compounds, with M =  La, Ce, Pr, Nd, Sm, Eu, Gd, Lu and Th.

PubMed

Royanian, E; Bauer, E; Kaldarar, H; Galatanu, A; Khan, R T; Hilscher, G; Michor, H; Reissner, M; Rogl, P; Sologub, O; Giester, G; Gonçalves, A P

2009-07-29

Novel ternary compounds, M(2)Pd(14+x)B(5-y) (M =  La, Ce, Pr, Nd, Sm, Eu, Gd, Lu, Th; x∼0.9, y∼0.1), have been synthesized by arc melting. The crystal structures of Nd(2)Pd(14+x)B(5-y) and Th(2)Pd(14+x)B(5-y) were determined from x-ray single-crystal data and both are closely related to the structure type of Sc(4)Ni(29)B(10). All compounds were characterized by Rietveld analyses and found to be isotypic with the Nd(2)Pd(14+x)B(5-y) type. Measurements of the temperature dependent susceptibility and specific heat as well as the temperature and field dependent resistivity were employed to derive basic information on bulk properties of these compounds. The electrical resistivity of M(2)Pd(14+x)B(5-y), in general, is characterized by small RRR (residual resistance ratio) values originating from defects inherent to the crystal structure. Whereas the compounds based on Ce, Nd, Sm and Gd exhibit magnetic order, those based on Pr and Eu seem to be non-magnetic, at least down to 400 mK. While the non-magnetic ground state of the Pr based compound is a consequence of crystalline electric field effects in the context of the non-Kramers ion Pr, the lack of magnetic order in the case of the Eu based compound results from an intermediate valence state of the Eu ion.

Dealing with pre-exposure prophylaxis-associated condom migration: changing the paradigm for men who have sex with men.

PubMed

Crosby, Richard A

2017-02-01

The behavioural aspects of pre-exposure prophylaxis (PrEP) are challenging, particularly the issue of condom migration. Three vital questions are: (1) at the population-level, will condom migration lead to increases in non-viral sexually transmissible infections?; (2) how can clinic-based counselling best promote the dual use of condoms and PrEP?; and (3) in future PrEP trials, what are the 'best practices' that should be used to avoid type 1 and type 2 errors that arise without accounting for condom use behaviours? This communication piece addresses each question and suggests the risk of a 'PrEP only' focus to widening health disparities.

Research on control strategy based on fuzzy PR for grid-connected inverter

NASA Astrophysics Data System (ADS)

Zhang, Qian; Guan, Weiguo; Miao, Wen

2018-04-01

In the traditional PI controller, there is static error in tracking ac signals. To solve the problem, the control strategy of a fuzzy PR and the grid voltage feed-forward is proposed. The fuzzy PR controller is to eliminate the static error of the system. It also adjusts parameters of PR controller in real time, which avoids the defect of fixed parameter fixed. The grid voltage feed-forward control can ensure the quality of current and improve the system's anti-interference ability when the grid voltage is distorted. Finally, the simulation results show that the system can output grid current with good quality and also has good dynamic and steady state performance.

Transactional Sex and Preferences for Pre-Exposure Prophylaxis (PrEP) Administration Modalities Among Men Who Have Sex With Men (MSM).

PubMed

Mgbako, Ofole; Park, Su Hyun; Mayer, Kenneth H; Schneider, John A; Goedel, William C; Hambrick, H Rhodes; Duncan, Dustin T

2018-04-10

Pre-exposure prophylaxis (PrEP) is an important biomedical human immunodeficiency virus (HIV) prevention tool gaining more popularity among Parisian men who have sex with men (MSM) who engage in transactional sex. This study examines the knowledge of, and willingness to use, different modalities of PrEP among this subgroup. Broadcast advertisements were placed on a geosocial-networking smartphone application with a link to a Web-based survey during three 24-hour periods in October 2016. Modified Poisson regression models were used to assess the association between engagement in transactional sex and preferences for each of these PrEP modalities. A total of 444 respondents were included. About 14% reported engagement in transactional sex. In all, 90% of MSM who engaged in transactional sex were knowledgeable of daily oral PrEP, while 13.3% were knowledgeable about long-acting injectable PrEP or penile or rectal microbicides. They were more likely to be aware of long-acting injectable PrEP (aRR = 2.52, 95% CI = 1.16 to 5.47) and willing to use daily oral PrEP (aRR = 1.48; 95% CI = 1.11 to 1.98) or long-acting injectable PrEP (aRR = 1.40; 95% CI = 1.09 to 1.81) than MSM who had not engaged in transactional sex. Long-acting injectable PrEP may be an important HIV-prevention option for MSM who engage in transactional sex if this modality is proven effective.

Brief Report: Context Matters: PrEP Adherence is Associated With Sexual Behavior Among HIV Serodiscordant Couples in East Africa.

PubMed

Haberer, Jessica E; Ngure, Kenneth; Muwonge, Timothy; Mugo, Nelly; Katabira, Elly; Heffron, Renee; Musinguzi, Nicholas; Bangsberg, David R; Celum, Connie; Baeten, Jared M

2017-12-15

Short message service (SMS) surveys are a promising tool for understanding whether preexposure prophylaxis (PrEP) adherence aligns with risk for HIV acquisition-a concept known as prevention-effective adherence. The Partners Demonstration Project was an open-label study of integrated PrEP and antiretroviral therapy (ART) delivery among high-risk HIV serodiscordant couples in East Africa. HIV-uninfected partners were offered PrEP until their HIV-infected partner had taken ART for ≥6 months. At 2 study sites, HIV-uninfected partners were offered enrollment into the Partners Mobile Adherence to PrEP (PMAP) substudy based on ongoing PrEP use, personal cell phone ownership, and ability to use SMS. SMS surveys asked about PrEP adherence and sexual activity in the previous 24 hours; these surveys were sent daily for the 7 days before and 7 days after routine study visits in the Partners Demonstration Project. The PMAP substudy enrolled 373 HIV-uninfected partners; 69% were men and mean age was 31 years. Participants completed 17,030 of 23,056 SMS surveys sent (74%) with a mean of 47 surveys per participant over 9.8 months of follow-up. While HIV-infected partner use of ART was <6 months, mean reported PrEP adherence was 92% on surveys concurrently reporting sex within the serodiscordant partnership, and 84% on surveys reporting no sex (P < 0.001). SMS surveys provided daily assessment of concurrent PrEP adherence and sexual behavior. Higher PrEP adherence was temporally associated with increased risk for HIV acquisition.

WebPrInSeS: automated full-length clone sequence identification and verification using high-throughput sequencing data.

PubMed

Massouras, Andreas; Decouttere, Frederik; Hens, Korneel; Deplancke, Bart

2010-07-01

High-throughput sequencing (HTS) is revolutionizing our ability to obtain cheap, fast and reliable sequence information. Many experimental approaches are expected to benefit from the incorporation of such sequencing features in their pipeline. Consequently, software tools that facilitate such an incorporation should be of great interest. In this context, we developed WebPrInSeS, a web server tool allowing automated full-length clone sequence identification and verification using HTS data. WebPrInSeS encompasses two separate software applications. The first is WebPrInSeS-C which performs automated sequence verification of user-defined open-reading frame (ORF) clone libraries. The second is WebPrInSeS-E, which identifies positive hits in cDNA or ORF-based library screening experiments such as yeast one- or two-hybrid assays. Both tools perform de novo assembly using HTS data from any of the three major sequencing platforms. Thus, WebPrInSeS provides a highly integrated, cost-effective and efficient way to sequence-verify or identify clones of interest. WebPrInSeS is available at http://webprinses.epfl.ch/ and is open to all users.

WebPrInSeS: automated full-length clone sequence identification and verification using high-throughput sequencing data

PubMed Central

Massouras, Andreas; Decouttere, Frederik; Hens, Korneel; Deplancke, Bart

2010-01-01

High-throughput sequencing (HTS) is revolutionizing our ability to obtain cheap, fast and reliable sequence information. Many experimental approaches are expected to benefit from the incorporation of such sequencing features in their pipeline. Consequently, software tools that facilitate such an incorporation should be of great interest. In this context, we developed WebPrInSeS, a web server tool allowing automated full-length clone sequence identification and verification using HTS data. WebPrInSeS encompasses two separate software applications. The first is WebPrInSeS-C which performs automated sequence verification of user-defined open-reading frame (ORF) clone libraries. The second is WebPrInSeS-E, which identifies positive hits in cDNA or ORF-based library screening experiments such as yeast one- or two-hybrid assays. Both tools perform de novo assembly using HTS data from any of the three major sequencing platforms. Thus, WebPrInSeS provides a highly integrated, cost-effective and efficient way to sequence-verify or identify clones of interest. WebPrInSeS is available at http://webprinses.epfl.ch/ and is open to all users. PMID:20501601

A heterobimetallic Ga/Yb-Schiff base complex for catalytic asymmetric alpha-addition of isocyanides to aldehydes.

PubMed

Mihara, Hisashi; Xu, Yingjie; Shepherd, Nicholas E; Matsunaga, Shigeki; Shibasaki, Masakatsu

2009-06-24

Development of a new heterobimetallic Ga(O-iPr)(3)/Yb(OTf)(3)/Schiff base 2d complex for catalytic asymmetric alpha-additions of isocyanides to aldehydes is described. Schiff base 2d derived from o-vanillin was suitable to utilize cationic rare earth metal triflates with good Lewis acidity in bimetallic Schiff base catalysis. The Ga(O-iPr)(3)/Yb(OTf)(3)/Schiff base 2d complex promoted asymmetric alpha-additions of alpha-isocyanoacetamides to aryl, heteroaryl, alkenyl, and alkyl aldehydes in good to excellent enantioselectivity (88-98% ee).

Red-backed vole brain promotes highly efficient in vitro amplification of abnormal prion protein from macaque and human brains infected with variant Creutzfeldt-Jakob disease agent.

USGS Publications Warehouse

Nemecek, Julie; Nag, Nabanita; Carlson, Christina M.; Schneider, Jay R.; Heisey, Dennis M.; Johnson, Christopher J.; Asher, David M.; Gregori, Luisa

2013-01-01

Rapid antemortem tests to detect individuals with transmissible spongiform encephalopathies (TSE) would contribute to public health. We investigated a technique known as protein misfolding cyclic amplification (PMCA) to amplify abnormal prion protein (PrPTSE) from highly diluted variant Creutzfeldt-Jakob disease (vCJD)-infected human and macaque brain homogenates, seeking to improve the rapid detection of PrPTSE in tissues and blood. Macaque vCJD PrPTSE did not amplify using normal macaque brain homogenate as substrate (intraspecies PMCA). Next, we tested interspecies PMCA with normal brain homogenate of the southern red-backed vole (RBV), a close relative of the bank vole, seeded with macaque vCJD PrPTSE. The RBV has a natural polymorphism at residue 170 of the PrP-encoding gene (N/N, S/S, and S/N). We investigated the effect of this polymorphism on amplification of human and macaque vCJD PrPTSE. Meadow vole brain (170N/N PrP genotype) was also included in the panel of substrates tested. Both humans and macaques have the same 170S/S PrP genotype. Macaque PrPTSE was best amplified with RBV 170S/S brain, although 170N/N and 170S/N were also competent substrates, while meadow vole brain was a poor substrate. In contrast, human PrPTSE demonstrated a striking narrow selectivity for PMCA substrate and was successfully amplified only with RBV 170S/S brain. These observations suggest that macaque PrPTSE was more permissive than human PrPTSE in selecting the competent RBV substrate. RBV 170S/S brain was used to assess the sensitivity of PMCA with PrPTSE from brains of humans and macaques with vCJD. PrPTSE signals were reproducibly detected by Western blot in dilutions through 10-12 of vCJD-infected 10% brain homogenates. This is the first report showing PrPTSE from vCJD-infected human and macaque brains efficiently amplified with RBV brain as the substrate. Based on our estimates, PMCA showed a sensitivity that might be sufficient to detect PrPTSE in vCJD-infected human and macaque blood.

Binding characteristics of the ovine membrane progesterone receptor alpha and expression of the receptor during the estrous cycle

PubMed Central

Ashley, Ryan L; Arreguin-Arevalo, J Alejandro; Nett, Terry M

2009-01-01

Background Classically, progesterone has been thought to act only through the well-known genomic pathway involving hormone binding to nuclear receptors and subsequent modulation of gene expression. However, there is increasing evidence for rapid, non-genomic effects of progesterone in a variety of mammalian tissues and it is possible that a membrane PR (mPR) is causing these events. We recently isolated and characterized an ovine mPR referred to as mPR-alpha, distinct from the nuclear PR. Based on predicted structural analysis, the ovine mPR-alpha possesses seven transmembrane domains typical of G protein-coupled receptors. Despite the homology to other reported mPRs, information pertaining to the steroid binding characteristics of the ovine mPR-alpha was lacking. Additionally, the ovine mPR-alpha transcript has been identified in the hypothalamus, pituitary, uterus, ovary and corpus luteum, yet changes in expression of the ovine mPR-alpha in these tissues were not known. Consequently, the purpose of this work was to determine the steroid binding characteristics of the ovine mPR-alpha and to investigate possible changes in expression of the ovine mPR-alpha in reproductive tissues throughout the estrous cycle. Methods Binding studies were performed using crude membrane fractions from CHO cells expressing the mPR-alpha. Using quantitative Real-time PCR we determined the expression pattern of mRNA for the ovine mPR-alpha during the ovine estrous cycle in tissues known to express the mPR-alpha. Jugular blood samples were also collected and analyzed for serum concentrations of P4 to ensure ewes were at the appropriate stage of their cycle. Results Only progesterone, 20alpha-hydroxyprogesterone and 17alpha-hydroxyprogesterone were able to displace binding of 3H-P4 (P < 0.001) to membrane fractions from CHO cells expressing ovine mPR-alpha. The average B-max and Kd values for three separate experiments were 624 +/- 119 fmol/micro gram protein and 122 +/- 50 nM, respectively. Significant changes in expression of mRNA for the mPR-alpha during the estrous cycle were noted in the corpus luteum and uterus. Conclusion The mPR-alpha specifically binds progestins and its expression was correlated to progesterone secretion during the ovine estrous cycle. Results from the present studies suggest that mPR-alpha may have an important physiological role during the ovine estrous cycle. PMID:19432978

Role of nuclear progesterone receptor isoforms in uterine pathophysiology

PubMed Central

Patel, Bansari; Elguero, Sonia; Thakore, Suruchi; Dahoud, Wissam; Bedaiwy, Mohamed; Mesiano, Sam

2015-01-01

BACKGROUND Progesterone is a key hormonal regulator of the female reproductive system. It plays a major role to prepare the uterus for implantation and in the establishment and maintenance of pregnancy. Actions of progesterone on the uterine tissues (endometrium, myometrium and cervix) are mediated by the combined effects of two progesterone receptor (PR) isoforms, designated PR-A and PR-B. Both receptors function primarily as ligand-activated transcription factors. Progesterone action on the uterine tissues is qualitatively and quantitatively determined by the relative levels and transcriptional activities of PR-A and PR-B. The transcriptional activity of the PR isoforms is affected by specific transcriptional coregulators and by PR post-translational modifications that affect gene promoter targeting. In this context, appropriate temporal and cell-specific expression and function of PR-A and PR-B are critical for normal uterine function. METHODS Relevant studies describing the role of PRs in uterine physiology and pathology (endometriosis, uterine leiomyoma, endometrial cancer, cervical cancer and recurrent pregnancy loss) were comprehensively searched using PubMed, Cochrane Library, Web of Science, and Google Scholar and critically reviewed. RESULTS Progesterone, acting through PR-A and PR-B, regulates the development and function of the endometrium and induces changes in cells essential for implantation and the establishment and maintenance of pregnancy. During pregnancy, progesterone via the PRs promotes myometrial relaxation and cervical closure. Withdrawal of PR-mediated progesterone signaling triggers menstruation and parturition. PR-mediated progesterone signaling is anti-mitogenic in endometrial epithelial cells, and as such, mitigates the tropic effects of estrogen on eutopic normal endometrium, and on ectopic implants in endometriosis. Similarly, ligand-activated PRs function as tumor suppressors in endometrial cancer cells through inhibition of key cellular signaling pathways required for growth. In contrast, progesterone via PR activation appears to increase leiomyoma growth. The exact role of PRs in cervical cancer is unclear. PRs regulate implantation and therefore aberrant PR function may be implicated in recurrent pregnancy loss (RPL). PRs likely regulate key immunogenic factors involved in RPL. However, the exact role of PRs in the pathophysiology of RPL and the use of progesterone for therapeutic benefit remains uncertain. CONCLUSIONS PRs are key mediators of progesterone action in uterine tissues and are essential for normal uterine function. Aberrant PR function (due to abnormal expression and/or function) is a major cause of uterine pathophysiology. Further investigation of the underlying mechanisms of PR isoform action in the uterus is required, as this knowledge will afford the opportunity to create progestin/PR-based therapeutics to treat various uterine pathologies. PMID:25406186

Evolution of structural, magnetic and transport behavior by Pr doping in SrRuO3

NASA Astrophysics Data System (ADS)

Gupta, Renu; Pramanik, A. K.

2018-05-01

Here we report the evolution of structural, magnetic and transport behavior in perovskite based ruthenates Sr1-xPrxRuO3 (x=0.0 and 0.1). The substitution of Pr on Sr site retains orthorhombic structure while we find the slight change in structural parameters. The SrRuO3 has itinerant ferromagnet (FM) type nature of ordering temperature ˜160 K and below the transition temperature showing large bifurcation between ZFC and FC magnetization. By Pr doping, the magnetic moment decreases with decreasing bifurcation of ZFC and FC. The ZFC data show three distinct peaks (three transition temperature; TM1,TM2 and TM3). The magnetization study of both the samples, at high temperature fitted with modified CWL showing the decreasing value of ordering temperature by Pr doping matches close to TM2. The low-temperature isothermal magnetization M (H) data show that the high field saturation moment has decreased by Pr doping. The Arrott plot gives spontaneous magnetization (Ms) which is also decreased by Pr substitution. Evolution of Rhodes-Wohlfarth ratio value increases, which suggests that FM in this system evolves toward the more itinerant type by Pr doping. The electrical resistivity ρ(T) of both the samples show metallic behavior, in the all temperature range and ρ(T) increases by Pr doping while around below 45 K, the resistivity decreases by Pr doping and this crossing temperature also matches with ZFC data.

Willingness to use pre-exposure prophylaxis for HIV prevention among men who have sex with men in Malaysia: Findings from an online survey

PubMed Central

Pang, Joselyn; Wei, Clayton Koh Thuan; Yee, Ilias Adam; Wang, Bangyuan; Cassolato, Matteo

2017-01-01

Objective We examined willingness to use pre-exposure prophylaxis (PrEP) for HIV prevention among men who have sex with men (MSM) in Malaysia. Methods An online survey of 990 MSM was conducted between March and April 2016. Eligibility criteria included being biological male, Malaysian citizen, 18 years of age or above, identifying as MSM, and being HIV negative or unknown status. Participants’ demographics, sexual and drug use behaviors, attitudes towards PrEP, and preferences regarding future access to PrEP were collected. Bivariate analysis and logistic regression were performed to determine factors associated with willingness to use PrEP. Results Fewer than half of participants (44%) knew about PrEP before completing the survey. Overall, 39% of the sample were willing to take PrEP. Multivariate logistic regression indicated that Malay men (AOR: 1.73, 95% CI:1.12, 2.70), having 2 or more male anal sex partners in the past 6 months (AOR: 1.98, 95% CI: 1.29, 3.05), previous knowledge of PrEP (AOR: 1.40, 95%CI: 1.06, 1.86), lack of confidence in practising safer sex (AOR: 1.36, 95% CI: 1.02, 1.81), and having ever paid for sex with a male partner (AOR: 1.39, 95% CI: 1.01, 1.91) were independently associated with greater willingness to use PrEP, while men who identified as heterosexual were less willing to use PrEP (AOR, 0.36, 95% CI: 0.13, 0.97). Majority of participants preferred to access PrEP at affordable cost below 100 Malaysian Ringgit (USD25) per month from community based organisations followed by private or government hospitals. Conclusions Overall, MSM in Malaysia reported a relatively low level of willingness to use PrEP, although willingness was higher among those previously aware of PrEP. There is a need to provide PrEP at affordable cost, increase demand and awareness of PrEP, and to provide access to this preventative medication via diverse, integrated and tailored sexual health services. PMID:28902857

Willingness to use pre-exposure prophylaxis for HIV prevention among men who have sex with men in Malaysia: Findings from an online survey.

PubMed

Lim, Sin How; Mburu, Gitau; Bourne, Adam; Pang, Joselyn; Wickersham, Jeffrey A; Wei, Clayton Koh Thuan; Yee, Ilias Adam; Wang, Bangyuan; Cassolato, Matteo; Azwa, Iskandar

2017-01-01

We examined willingness to use pre-exposure prophylaxis (PrEP) for HIV prevention among men who have sex with men (MSM) in Malaysia. An online survey of 990 MSM was conducted between March and April 2016. Eligibility criteria included being biological male, Malaysian citizen, 18 years of age or above, identifying as MSM, and being HIV negative or unknown status. Participants' demographics, sexual and drug use behaviors, attitudes towards PrEP, and preferences regarding future access to PrEP were collected. Bivariate analysis and logistic regression were performed to determine factors associated with willingness to use PrEP. Fewer than half of participants (44%) knew about PrEP before completing the survey. Overall, 39% of the sample were willing to take PrEP. Multivariate logistic regression indicated that Malay men (AOR: 1.73, 95% CI:1.12, 2.70), having 2 or more male anal sex partners in the past 6 months (AOR: 1.98, 95% CI: 1.29, 3.05), previous knowledge of PrEP (AOR: 1.40, 95%CI: 1.06, 1.86), lack of confidence in practising safer sex (AOR: 1.36, 95% CI: 1.02, 1.81), and having ever paid for sex with a male partner (AOR: 1.39, 95% CI: 1.01, 1.91) were independently associated with greater willingness to use PrEP, while men who identified as heterosexual were less willing to use PrEP (AOR, 0.36, 95% CI: 0.13, 0.97). Majority of participants preferred to access PrEP at affordable cost below 100 Malaysian Ringgit (USD25) per month from community based organisations followed by private or government hospitals. Overall, MSM in Malaysia reported a relatively low level of willingness to use PrEP, although willingness was higher among those previously aware of PrEP. There is a need to provide PrEP at affordable cost, increase demand and awareness of PrEP, and to provide access to this preventative medication via diverse, integrated and tailored sexual health services.

Engineering human immunodeficiency virus 1 protease heterodimers as macromolecular inhibitors of viral maturation.

PubMed Central

McPhee, F; Good, A C; Kuntz, I D; Craik, C S

1996-01-01

Dimerization of human immunodeficiency virus type 1 protease (HIV-1 PR) monomers is an essential prerequisite for viral proteolytic activity and the subsequent generation of infectious virus particles. Disruption of the dimer interface inhibits this activity as does formation of heterodimers between wild-type and defective monomers. A structure-based approach was used to identify amino acid substitutions at the dimer interface of HIV-1 PR that facilitate preferential association of heterodimers and inhibit self-association of the defective monomers. Expression of the designed PR monomers inhibits activity of wild-type HIV-1 PR and viral infectivity when assayed in an ex vivo model system. These results show that it is possible to design PR monomers as macromolecular inhibitors that may provide an alternative to small molecule inhibitors for the treatment of HIV infection. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8876160

Effect of Pr 3+ concentration on thermoluminescence from K 2Y 1- xPr xF 5 crystals

NASA Astrophysics Data System (ADS)

Marcazzo, J.; Santiago, M.; Caselli, E.; Nariyama, N.; Khaidukov, N. M.

2004-06-01

Thermoluminescence dosimetric characteristics of K 2YF 5 crystals doped with Pr 3+ are reported for the first time. The efficiency of the 0.5 at.% Pr 3+ doped K 2YF 5 crystal has been found to be maximum for this concentration series and three times higher than that of the commercial dosimeter TLD-700. The thermoluminescence glow curve of this novel phosphor has no appreciable fading. Furthermore, it bears linear dose response and good stability after reutilization. According to these results, K 2YF 5:Pr 3+ appears to be a promising base for developing effective phosphors for TL solid state dosimetry. In this context, the spectral composition of the TL emission is also mentioned along with the values obtained by glow curve deconvolution for the trap parameters characterising electron trap centres involved in thermoluminescence.

MR-based attenuation correction methods for improved PET quantification in lesions within bone and susceptibility artifact regions.

PubMed

Bezrukov, Ilja; Schmidt, Holger; Mantlik, Frédéric; Schwenzer, Nina; Brendle, Cornelia; Schölkopf, Bernhard; Pichler, Bernd J

2013-10-01

Hybrid PET/MR systems have recently entered clinical practice. Thus, the accuracy of MR-based attenuation correction in simultaneously acquired data can now be investigated. We assessed the accuracy of 4 methods of MR-based attenuation correction in lesions within soft tissue, bone, and MR susceptibility artifacts: 2 segmentation-based methods (SEG1, provided by the manufacturer, and SEG2, a method with atlas-based susceptibility artifact correction); an atlas- and pattern recognition-based method (AT&PR), which also used artifact correction; and a new method combining AT&PR and SEG2 (SEG2wBONE). Attenuation maps were calculated for the PET/MR datasets of 10 patients acquired on a whole-body PET/MR system, allowing for simultaneous acquisition of PET and MR data. Eighty percent iso-contour volumes of interest were placed on lesions in soft tissue (n = 21), in bone (n = 20), near bone (n = 19), and within or near MR susceptibility artifacts (n = 9). Relative mean volume-of-interest differences were calculated with CT-based attenuation correction as a reference. For soft-tissue lesions, none of the methods revealed a significant difference in PET standardized uptake value relative to CT-based attenuation correction (SEG1, -2.6% ± 5.8%; SEG2, -1.6% ± 4.9%; AT&PR, -4.7% ± 6.5%; SEG2wBONE, 0.2% ± 5.3%). For bone lesions, underestimation of PET standardized uptake values was found for all methods, with minimized error for the atlas-based approaches (SEG1, -16.1% ± 9.7%; SEG2, -11.0% ± 6.7%; AT&PR, -6.6% ± 5.0%; SEG2wBONE, -4.7% ± 4.4%). For lesions near bone, underestimations of lower magnitude were observed (SEG1, -12.0% ± 7.4%; SEG2, -9.2% ± 6.5%; AT&PR, -4.6% ± 7.8%; SEG2wBONE, -4.2% ± 6.2%). For lesions affected by MR susceptibility artifacts, quantification errors could be reduced using the atlas-based artifact correction (SEG1, -54.0% ± 38.4%; SEG2, -15.0% ± 12.2%; AT&PR, -4.1% ± 11.2%; SEG2wBONE, 0.6% ± 11.1%). For soft-tissue lesions, none of the evaluated methods showed statistically significant errors. For bone lesions, significant underestimations of -16% and -11% occurred for methods in which bone tissue was ignored (SEG1 and SEG2). In the present attenuation correction schemes, uncorrected MR susceptibility artifacts typically result in reduced attenuation values, potentially leading to highly reduced PET standardized uptake values, rendering lesions indistinguishable from background. While AT&PR and SEG2wBONE show accurate results in both soft tissue and bone, SEG2wBONE uses a two-step approach for tissue classification, which increases the robustness of prediction and can be applied retrospectively if more precision in bone areas is needed.

[USE OF PROTECTIVE LUNG VENTILATION REGIMEN IN CARDIAC SURGERY PATIENTS.

PubMed

Pshenichniy, T A; Akselrod, B A; Titova, I V; Trekova, N A; Khrustaleva, M V

2017-09-01

In cardiac surgery, protective lung ventilation and/or preventive brdnchoscopy (PB) are able to decrease lung injury effects of cardiopulmonary bypass (CPB) and mechanical ventilation. define lung complication risks, evaluate the effect ofprotective lung ventilation (PLV) on lung functioning, and investigate the feasibility ofpreventive PB in higher pulmonary risk (PR) patients. 66 patients participated in prospective randomized research. Allocation was based on PR and intraoperative mechanical ventilation type. PLV includedfollowing parameters: PCK PIP - up to 20 cm H20, Vt - 6 ml/ kg of PBW, PEEP - 5-10 cm H20, IE ratio - 1:1.5-1:1, EtCO2 - 35-42 mm Hg, FiO2 - 45-60%, lung ventilation during CPB, alveolar recruitment. Four groups were formed: A - higher PR plus PLV- B - higher PR plus conventional LV (CLV), C - lower PR plus PLV- D - lower PR plus CLV PIP PEEP dynamic compliance, p/f ratio and intrapulmonary shunt (Qs/Qt) were recorded. Seventeen patients of group A underwent PB. Advanced dynamic compliance, higher p/f ratio and lower Qs/Qt were seen in group A, in comparison with group B (p< 0.05). Lower Qs/Qt was seen in group C, in comparison with group D (p<0.05). Mucus obstruction of subsegmental bronchi was observed in 53.3% of higher PR patients. More than half ofpatients without PB sufferedfrom postoperative lung complications (70.4 vs. 34.2 7%, p

Associations between lamb survival and prion protein genotype: analysis of data for ten sheep breeds in Great Britain

PubMed Central

Gubbins, Simon; Cook, Charlotte J; Hyder, Kieran; Boulton, Kay; Davis, Carol; Thomas, Eurion; Haresign, Will; Bishop, Stephen C; Villanueva, Beatriz; Eglin, Rachel D

2009-01-01

Background Selective breeding programmes, based on prion protein (PrP) genotype, have been introduced throughout the European Union to reduce the risk of sheep transmissible spongiform encephalopathies (TSEs). These programmes could have negative consequences on other important traits, such as fitness and production traits, if the PrP gene has pleiotropic effects or is in linkage disequilibrium with genes affecting these traits. This paper presents the results of an investigation into associations between lamb survival and PrP genotype in ten mainstream sheep breeds in Great Britain (GB). In addition, the reasons for lamb deaths were examined in order to identify any associations between these and PrP genotype. Results Survival times from birth to weaning were analysed for over 38000 lambs (2427 dead and 36096 live lambs) from 128 flocks using Cox proportional hazard models for each breed, including additive animal genetic effects. No significant associations between PrP genotype and lamb survival were identified, except in the Charollais breed for which there was a higher risk of mortality in lambs of the ARR/VRQ genotype compared with those of the ARR/ARR genotype. Significant effects of birth weight, litter size, sex, age of dam and year of birth on survival were also identified. For all breeds the reasons for death changed significantly with age; however, no significant associations between reason for death and PrP genotype were found for any of the breeds. Conclusion This study found no evidence to suggest that a selective breeding programme based on PrP genotype will have a detrimental effect on lamb survival. The only significant effect of PrP genotype identified was likely to be of little consequence because an increased risk of mortality was associated with a genotype that is selected against in current breeding strategies. PMID:19159456

Challenges and potential barriers to the uptake of antiretroviral-based prevention in Asia and the Pacific region.

PubMed

Lo, Ying-Ru; Kato, Masaya; Phanuphak, Nittaya; Fujita, Masami; Duc, Duong Bui; Sopheap, Seng; Pendse, Razia; Yu, Dongbao; Wu, Zunyou; Chariyalertsak, Suwat

2014-07-01

Evidence has emerged over the past few years on the effectiveness of antiretroviral-based prevention technologies to prevent (i) HIV transmission while decreasing morbidity and mortality in HIV-infected persons, and (ii) HIV acquisition in HIV-uninfected individuals through pre-exposure prophylaxis (PrEP). Only few of the planned studies on treatment as prevention (TasP) are conducted in Asia. TasP might be more feasible and effective in concentrated rather than in generalised epidemics, as resources for HIV testing and antiretroviral treatment could focus on confined and much smaller populations than in the generalised epidemics observed in sub-Saharan Africa. Several countries such as Cambodia, China, Thailand and Vietnam, are now paving the way to success. Similar challenges arise for both TasP and PrEP. However, the operational issues for PrEP are amplified by the need for frequent retesting and ensuring adherence. This paper describes challenges for the implementation of antiretroviral-based prevention and makes the case that TasP and PrEP implementation research in Asia is much needed to provide insights into the feasibility of these interventions in populations where firm evidence of 'real world' effectiveness is still lacking.

Physical Activity and Yoga-Based Approaches for Pregnancy-Related Low Back and Pelvic Pain.

PubMed

Kinser, Patricia Anne; Pauli, Jena; Jallo, Nancy; Shall, Mary; Karst, Kailee; Hoekstra, Michelle; Starkweather, Angela

To conduct an integrative review to evaluate current literature about nonpharmacologic, easily accessible management strategies for pregnancy-related low back and pelvic pain (PR-LBPP). PubMed, CINAHL, Cochrane Database of Systematic Reviews. Original research articles were considered for review if they were full-length publications written in English and published in peer-reviewed journals from 2005 through 2015, included measures of pain and symptoms related to PR-LBPP, and evaluated treatment modalities that used a physical exercise or yoga-based approach for the described conditions. Electronic database searches yielded 1,435 articles. A total of 15 articles met eligibility criteria for further review. These modalities show preliminary promise for pain relief and other related symptoms, including stress and depression. However, our findings also indicate several gaps in knowledge about these therapies for PR-LBPP and methodologic issues with the current literature. Although additional research is required, the results of this integrative review suggest that clinicians may consider recommending nonpharmacologic treatment options, such as gentle physical activity and yoga-based interventions, for PR-LBPP and related symptoms. Copyright © 2017 AWHONN, the Association of Women’s Health, Obstetric and Neonatal Nurses. Published by Elsevier Inc. All rights reserved.

Evaluation of the filling ability of artificial lateral canals using calcium silicate-based and epoxy resin-based endodontic sealers and two gutta-percha filling techniques.

PubMed

Fernández, R; Restrepo, J S; Aristizábal, D C; Álvarez, L G

2016-04-01

To evaluate the ability of a calcium silicate-based sealer (iRoot SP) and an epoxy resin-based sealer (Topseal) using two gutta-percha filling techniques to fill artificial lateral canals (ALCs). Seventy single-rooted human teeth were selected. Ten of these were used to obtain pilot data. Three ALCs were produced on mesial and distal surfaces of each root, one in each third, using size 10 engine reamers. The roots were randomly assigned to four experimental groups according to the filling technique and sealer used: 1, cold gutta-percha (single-point technique) with iRoot SP (SP-iR); 2, cold gutta-percha (single-point technique) with Topseal (SP-T); 3, continuous wave of condensation technique with iRoot SP (CWC-iR); and 4, continuous wave of condensation technique with Topseal (CWC-T). Digital periapical radiographs were taken. After the sealer had set, the roots were demineralized, cleared in methyl-salicylate and examined under a stereomicroscope. The depth of penetration of sealer and/or gutta-percha into the ALC was scored using a 5-point system, conducting an analysis on four surfaces. Filling scores of 0-1 were considered not acceptable, whilst scores of 2-4 were considered acceptable. Pearson's chi-square test was used to compare the experimental groups (P < 0.05). CWC-T was associated with the highest acceptable filling (57.8%), followed by CWC-iR (53.3%), SP-T (48.9%) and SP-iR (36.7%). Only when SP-iR was compared to the other groups, was the difference significant (P < 0.05). The apical third was associated with the lowest acceptable filling (37.5%). It was followed, in ascending order, by the middle (51.6%) and coronal thirds (58.3%). These differences were significant only when the apical thirds were compared to the other root thirds (P < 0.05). The calcium silicate-based sealer with continuous wave of condensation was more effective in artificial filling lateral canals than the single-point technique. The epoxy resin-based sealer with both filling techniques was effective in artificial filling lateral canals. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

2. View of sugar mill ruins looking N showing chimney ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. View of sugar mill ruins looking N showing chimney at left and masonry base of steam engine and cane mill at right. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

7. Detail view of mill wall ruins looking E showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Detail view of mill wall ruins looking E showing arched openings for Jamaican Train and archeological excavations at base of wall. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

VIEW OF SUGAR MILL RUINS LOOKING NORTH SHOWING CHIMNEY AT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF SUGAR MILL RUINS LOOKING NORTH SHOWING CHIMNEY AT LEFT AND MASONRY BASE OF STEAM ENGINE AND CANE MILL AT RIGHT - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

Preventing HIV among adolescents with oral PrEP: observations and challenges in the United States and South Africa

PubMed Central

Hosek, Sybil; Celum, Connie; Wilson, Craig M; Kapogiannis, Bill; Delany-Moretlwe, Sinead; Bekker, Linda-Gail

2016-01-01

Introduction Adolescents and young adults aged <25 are a key population in the HIV epidemic, with very high HIV incidence rates in many geographic settings and a large number who have limited access to prevention services. Thus, any biomedical HIV prevention approach should prepare licensure and implementation strategies for young populations. Oral pre-exposure prophylaxis (PrEP) is the first antiretroviral-based prevention intervention with proven efficacy across many settings and populations, and regulatory and policy approvals at global and national levels are occurring rapidly. We discuss available data from studies in the United States and South Africa on the use of oral PrEP for HIV prevention in adolescent minors, along with some of the implementation challenges. Discussion Ongoing studies in the United States and South Africa among youth under the age of 18 should provide the safety data needed by the end of 2016 to contribute to licensure of Truvada as daily PrEP in adolescents. The challenges of completing these studies as well as foreseeable broader challenges highlighted by this work are presented. Adherence to daily PrEP is a greater challenge for younger populations, and poor adherence was associated with decreased efficacy in all PrEP trials. Individual-level barriers include limited familiarity with antiretroviral-based prevention, stigma, product storage, and social support. Structural challenges include healthcare financing for PrEP, clinician acceptability and comfort with PrEP delivery, and the limited youth-friendly health services available. These challenges are discussed in the context of the work done to date in the United States and South Africa, but will likely be magnified in the setting of limited resources in many other countries that are heavily impacted by HIV. Conclusions Adolescent populations are particularly vulnerable to HIV, and oral PrEP in these populations is likely to have an impact on population-level HIV incidence. The challenges of disseminating an HIV biomedical prevention tool requiring daily usage in adolescents are formidable, but addressing these issues and starting dialogues will lay the groundwork for the many other HIV prevention tools now being developed and tested. PMID:27760684

Common and Rare Coding Genetic Variation Underlying the Electrocardiographic PR Interval.

PubMed

Lin, Honghuang; van Setten, Jessica; Smith, Albert V; Bihlmeyer, Nathan A; Warren, Helen R; Brody, Jennifer A; Radmanesh, Farid; Hall, Leanne; Grarup, Niels; Müller-Nurasyid, Martina; Boutin, Thibaud; Verweij, Niek; Lin, Henry J; Li-Gao, Ruifang; van den Berg, Marten E; Marten, Jonathan; Weiss, Stefan; Prins, Bram P; Haessler, Jeffrey; Lyytikäinen, Leo-Pekka; Mei, Hao; Harris, Tamara B; Launer, Lenore J; Li, Man; Alonso, Alvaro; Soliman, Elsayed Z; Connell, John M; Huang, Paul L; Weng, Lu-Chen; Jameson, Heather S; Hucker, William; Hanley, Alan; Tucker, Nathan R; Chen, Yii-Der Ida; Bis, Joshua C; Rice, Kenneth M; Sitlani, Colleen M; Kors, Jan A; Xie, Zhijun; Wen, Chengping; Magnani, Jared W; Nelson, Christopher P; Kanters, Jørgen K; Sinner, Moritz F; Strauch, Konstantin; Peters, Annette; Waldenberger, Melanie; Meitinger, Thomas; Bork-Jensen, Jette; Pedersen, Oluf; Linneberg, Allan; Rudan, Igor; de Boer, Rudolf A; van der Meer, Peter; Yao, Jie; Guo, Xiuqing; Taylor, Kent D; Sotoodehnia, Nona; Rotter, Jerome I; Mook-Kanamori, Dennis O; Trompet, Stella; Rivadeneira, Fernando; Uitterlinden, André; Eijgelsheim, Mark; Padmanabhan, Sandosh; Smith, Blair H; Völzke, Henry; Felix, Stephan B; Homuth, Georg; Völker, Uwe; Mangino, Massimo; Spector, Timothy D; Bots, Michiel L; Perez, Marco; Kähönen, Mika; Raitakari, Olli T; Gudnason, Vilmundur; Arking, Dan E; Munroe, Patricia B; Psaty, Bruce M; van Duijn, Cornelia M; Benjamin, Emelia J; Rosand, Jonathan; Samani, Nilesh J; Hansen, Torben; Kääb, Stefan; Polasek, Ozren; van der Harst, Pim; Heckbert, Susan R; Jukema, J Wouter; Stricker, Bruno H; Hayward, Caroline; Dörr, Marcus; Jamshidi, Yalda; Asselbergs, Folkert W; Kooperberg, Charles; Lehtimäki, Terho; Wilson, James G; Ellinor, Patrick T; Lubitz, Steven A; Isaacs, Aaron

2018-05-01

Electrical conduction from the cardiac sinoatrial node to the ventricles is critical for normal heart function. Genome-wide association studies have identified more than a dozen common genetic loci that are associated with PR interval. However, it is unclear whether rare and low-frequency variants also contribute to PR interval heritability. We performed large-scale meta-analyses of the PR interval that included 83 367 participants of European ancestry and 9436 of African ancestry. We examined both common and rare variants associated with the PR interval. We identified 31 genetic loci that were significantly associated with PR interval after Bonferroni correction ( P <1.2×10 -6 ), including 11 novel loci that have not been reported previously. Many of these loci are involved in heart morphogenesis. In gene-based analysis, we found that multiple rare variants at MYH6 ( P =5.9×10 -11 ) and SCN5A ( P =1.1×10 -7 ) were associated with PR interval. SCN5A locus also was implicated in the common variant analysis, whereas MYH6 was a novel locus. We identified common variants at 11 novel loci and rare variants within 2 gene regions that were significantly associated with PR interval. Our findings provide novel insights to the current understanding of atrioventricular conduction, which is critical for cardiac activity and an important determinant of health. © 2018 American Heart Association, Inc.

Altered Gag Polyprotein Cleavage Specificity of Feline Immunodeficiency Virus/Human Immunodeficiency Virus Mutant Proteases as Demonstrated in a Cell-Based Expression System

PubMed Central

Lin, Ying-Chuan; Brik, Ashraf; de Parseval, Aymeric; Tam, Karen; Torbett, Bruce E.; Wong, Chi-Huey; Elder, John H.

2006-01-01

We have used feline immunodeficiency virus (FIV) protease (PR) as a mutational system to study the molecular basis of substrate-inhibitor specificity for lentivirus PRs, with a focus on human immunodeficiency virus type 1 (HIV-1) PR. Our previous mutagenesis studies demonstrated that discrete substitutions in the active site of FIV PR with structurally equivalent residues of HIV-1 PR dramatically altered the specificity of the mutant PRs in in vitro analyses. Here, we have expanded these studies to analyze the specificity changes in each mutant FIV PR expressed in the context of the natural Gag-Pol polyprotein ex vivo. Expression mutants were prepared in which 4 to 12 HIV-1-equivalent substitutions were made in FIV PR, and cleavage of each Gag-Pol polyprotein was then assessed in pseudovirions from transduced cells. The findings demonstrated that, as with in vitro analyses, inhibitor specificities of the mutants showed increased HIV-1 PR character when analyzed against the natural substrate. In addition, all of the mutant PRs still processed the FIV polyprotein but the apparent order of processing was altered relative to that observed with wild-type FIV PR. Given the importance of the order in which Gag-Pol is processed, these findings likely explain the failure to produce infectious FIVs bearing these mutations. PMID:16873240

Evaluation of electrical propagation delay with cardiomyocytes by photosensitization reaction in vitro

NASA Astrophysics Data System (ADS)

Doi, Marika; Ogawa, Emiyu; Arai, Tsunenori

2017-02-01

In order to study cardiomyocyte electrical conduction damage by a photosensitization reaction (PR) mostly comes from outside of the cells in a few minutes after the PR, we studied propagation delay of contact action potential with cardiomyocyte by the PR. To determine appropriate PR condition for tachyarrhythmia ablation, a precise electrophysiological experiment in vitro has been preferable. We measured the contact action potential using a microelectrode array system of which information may be correct than conventional Ca2+ measurement. We investigated the propagation delays of an evoked potential to evaluate the electrical conduction damage by the PR. Rat cardiomyocytes were cultivated for 5-7 days on a dish with which 64 electrodes were patterned, in an incubator controlled to 37°C, 5% CO2. The following conditions were used for the PR: 40 μg/ml talapordfin sodium and 290 mW/cm2, 40-78 J/cm2 for an irradiation. A 2D map was obtained to visualize the propagation delays of the evoked potential. The propagation speed, which was calculated based on the measured propagation delays, was decreased by about 30-50% on average of all electrodes after the PR. Therefore, we think 2D propagation delays measurement of the evoked potential with contact action potential measuring system might be available to evaluate the acute electrical conduction damage of cardiomyocyte by the PR.

The impact of direct-to-consumer personal genomic testing on perceived risk of breast, prostate, colorectal, and lung cancer: findings from the PGen study.

PubMed

Carere, Deanna Alexis; VanderWeele, Tyler; Moreno, Tanya A; Mountain, Joanna L; Roberts, J Scott; Kraft, Peter; Green, Robert C

2015-10-15

Direct access to genomic information has the potential to transform cancer risk counseling. We measured the impact of direct-to-consumer genomic risk information on changes to perceived risk (ΔPR) of breast, prostate, colorectal and lung cancer among personal genomic testing (PGT) customers. We hypothesized that ΔPR would reflect directionality of risk estimates, attenuate with time, and be modified by participant characteristics. Pathway Genomics and 23andMe customers were surveyed prior to receiving PGT results, and 2 weeks and 6 months post-results. For each cancer, PR was measured on a 5-point ordinal scale from "much lower than average" to "much higher than average." PGT results, based on genotyping of common genetic variants, were dichotomized as elevated or average risk. The relationship between risk estimate and ΔPR was evaluated with linear regression; generalized estimating equations modeled this relationship over time. With the exception of lung cancer (for which ΔPR was positive regardless of result), elevated risk results were significantly associated with positive ΔPR, and average risk results with negative ΔPR (e.g., prostate cancer, 2 weeks: least squares-adjusted ΔPR = 0.77 for elevated risk versus -0.21 for average risk; p-valuedifference < 0.0001) among 1154 participants. Large changes were rare: for each cancer, <4 % of participants overall reported a ΔPR of ±3 or more units. Effect modification by age, cancer family history, and baseline interest was observed for breast, colorectal, and lung cancer, respectively. A pattern of decreasing impact on ΔPR over time was consistently observed, but this trend was significant only in the case of colorectal cancer. We have quantified the effect on consumer risk perception of returning genetic-based cancer risk information directly to consumers without clinician mediation. Provided via PGT, this information has a measurable but modest effect on perceived cancer risk, and one that is in some cases modified by consumers' non-genetic risk context. Our observations of modest marginal effect sizes, infrequent extreme changes in perceived risk, and a pattern of diminishing impact with time, suggest that the ability of PGT to effect changes to cancer screening and prevention behaviors may be limited by relatively small changes to perceived risk.

Le contrôle des infections au cabinet du pédiatre

PubMed Central

2008-01-01

RÉSUMÉ La transmission des infections au cabinet du pédiatre est de plus en plus préoccupante. Le présent document expose les voies de transmission des infections et les principes sous-jacents aux mesures actuelles pour contrôler les infections. Pour prévenir les infections, il faut bien concevoir le cabinet et adopter des politiques administratives et de triage convenables, de même que des pratiques de base pour les soins de tous les patients (p. ex., hygiène des mains, port de gants, de masques, de lunettes de protection et d’une blouse d’hôpital pour des interventions précises; nettoyage, désinfection et stérilisation convenables des surfaces et du matériel, y compris les jouets, et techniques d’asepsie en cas d’interventions effractives) et des précautions additionnelles en cas d’infections précises. Le personnel doit avoir reçu les vaccins pertinents, et les personnes infectées doivent respecter les politiques de restriction au travail.

Progesterone action in breast, uterine, and ovarian cancers

PubMed Central

Diep, Caroline H.; Daniel, Andrea R.; Mauro, Laura J.; Knutson, Todd P.; Lange, Carol A.

2015-01-01

Progesterone and progesterone receptors (PR) are essential for the development and cyclical regulation of hormone-responsive tissues including the breast and reproductive tract. Altered functions of PR isoforms contribute to the pathogenesis of tumors that arise in these tissues. In the breast, progesterone acts in concert with estrogen to promote proliferative and pro-survival gene programs. In sharp contrast, progesterone inhibits estrogen-driven growth in the uterus and protects the ovary from neoplastic transformation. Progesterone-dependent actions and associated biology in diverse tissues and tumors are mediated by two progesterone receptor isoforms, PR-A and PR-B. These isoforms are subject to altered transcriptional activity or expression levels, differential cross-talk with growth factor signaling pathways, and distinct post-translational modifications and cofactor binding partners. Herein, we summarize and discuss the recent literature focused on progesterone and PR isoform-specific actions in breast, uterine, and ovarian cancers. Understanding the complexity of context-dependent PR actions in these tissues is critical to developing new models that will allow us to advance our knowledge base with the goal of revealing novel and efficacious therapeutic regimens for these hormone-responsive diseases. PMID:25587053

New examples of ternary rare-earth metal boride carbides containing finite boron carbon chains: The crystal and electronic structure of RE15B6C20 (RE=Pr, Nd)

NASA Astrophysics Data System (ADS)

Babizhetskyy, Volodymyr; Mattausch, Hansjürgen; Simon, Arndt; Hiebl, Kurt; Ben Yahia, Mouna; Gautier, Régis; Halet, Jean-François

2008-08-01

The ternary rare-earth metal boride carbides RE15B6C20 (RE=Pr, Nd) were synthesized by co-melting the elements. They exist above 1270 K. Their crystal structures were determined from single-crystal X-ray diffraction data. Both crystallize in the space group P1¯, Z=1, a=8.3431(8) Å, b=9.2492(9) Å, c=8.3581(8) Å, α=84.72(1)°, β=89.68(1)°, γ =84.23(1)° (R1=0.041 (wR2=0.10) for 3291 reflections with Io>2σ(Io)) for Pr15B6C20, and a=8.284(1) Å, b=9.228(1) Å, c=8.309(1) Å, α=84.74(1)°, β=89.68(1)°, γ=84.17(2)° (R1=0.033 (wR2=0.049) for 2970 reflections with Io>2σ(Io)) for Nd15B6C20. Their structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated and distorted square nets, leading to cavities filled with unprecedented B2C4 finite chains, disordered C3 entities and isolated carbon atoms, respectively. Structural and theoretical analyses suggest the ionic formulation (RE3+)15([B2C4]6-)3([C3]4-)2(C4-)2·11ē. Accordingly, density functional theory calculations indicate that the compounds are metallic. Both structural arguments as well as energy calculations on different boron vs. carbon distributions in the B2C4 chains support the presence of a CBCCBC unit. Pr15B6C18 exhibits antiferromagnetic order at TN=7.9 K, followed by a meta-magnetic transition above a critical external field B>0.03 T. On the other hand, Nd15B6C18 is a ferromagnet below TC≈40 K.

Assessment of combined antiandrogenic effects of binary parabens mixtures in a yeast-based reporter assay.

PubMed

Ma, Dehua; Chen, Lujun; Zhu, Xiaobiao; Li, Feifei; Liu, Cong; Liu, Rui

2014-05-01

To date, toxicological studies of endocrine disrupting chemicals (EDCs) have typically focused on single chemical exposures and associated effects. However, exposure to EDCs mixtures in the environment is common. Antiandrogens represent a group of EDCs, which draw increasing attention due to their resultant demasculinization and sexual disruption of aquatic organisms. Although there are a number of in vivo and in vitro studies investigating the combined effects of antiandrogen mixtures, these studies are mainly on selected model compounds such as flutamide, procymidone, and vinclozolin. The aim of the present study is to investigate the combined antiandrogenic effects of parabens, which are widely used antiandrogens in industrial and domestic commodities. A yeast-based human androgen receptor (hAR) assay (YAS) was applied to assess the antiandrogenic activities of n-propylparaben (nPrP), iso-propylparaben (iPrP), methylparaben (MeP), and 4-n-pentylphenol (PeP), as well as the binary mixtures of nPrP with each of the other three antiandrogens. All of the four compounds could exhibit antiandrogenic activity via the hAR. A linear interaction model was applied to quantitatively analyze the interaction between nPrP and each of the other three antiandrogens. The isoboles method was modified to show the variation of combined effects as the concentrations of mixed antiandrogens were changed. Graphs were constructed to show isoeffective curves of three binary mixtures based on the fitted linear interaction model and to evaluate the interaction of the mixed antiandrogens (synergism or antagonism). The combined effect of equimolar combinations of the three mixtures was also considered with the nonlinear isoboles method. The main effect parameters and interaction effect parameters in the linear interaction models of the three mixtures were different from zero. The results showed that any two antiandrogens in their binary mixtures tended to exert equal antiandrogenic activity in the linear concentration ranges. The antiandrogenicity of the binary mixture and the concentration of nPrP were fitted to a sigmoidal model if the concentrations of the other antiandrogens (iPrP, MeP, and PeP) in the mixture were lower than the AR saturation concentrations. Some concave isoboles above the additivity line appeared in all the three mixtures. There were some synergistic effects of the binary mixture of nPrP and MeP at low concentrations in the linear concentration ranges. Interesting, when the antiandrogens concentrations approached the saturation, the interaction between chemicals were antagonistic for all the three mixtures tested. When the toxicity of the three mixtures was assessed using nonlinear isoboles, only antagonism was observed for equimolar combinations of nPrP and iPrP as the concentrations were increased from the no-observed-effect-concentration (NOEC) to effective concentration of 80%. In addition, the interactions were changed from synergistic to antagonistic as effective concentrations were increased in the equimolar combinations of nPrP and MeP, as well as nPrP and PeP. The combined effects of three binary antiandrogens mixtures in the linear ranges were successfully evaluated by curve fitting and isoboles. The combined effects of specific binary mixtures varied depending on the concentrations of the chemicals in the mixtures. At low concentrations in the linear concentration ranges, there was synergistic interaction existing in the binary mixture of nPrP and MeP. The interaction tended to be antagonistic as the antiandrogens approached saturation concentrations in mixtures of nPrP with each of the other three antiandrogens. The synergistic interaction was also found in the equimolar combinations of nPrP and MeP, as well as nPrP and PeP, at low concentrations with another method of nonlinear isoboles. The mixture activities of binary antiandrogens had a tendency towards antagonism at high concentrations and synergism at low concentrations.

Perspective: Web-based machine learning models for real-time screening of thermoelectric materials properties

NASA Astrophysics Data System (ADS)

Gaultois, Michael W.; Oliynyk, Anton O.; Mar, Arthur; Sparks, Taylor D.; Mulholland, Gregory J.; Meredig, Bryce

2016-05-01

The experimental search for new thermoelectric materials remains largely confined to a limited set of successful chemical and structural families, such as chalcogenides, skutterudites, and Zintl phases. In principle, computational tools such as density functional theory (DFT) offer the possibility of rationally guiding experimental synthesis efforts toward very different chemistries. However, in practice, predicting thermoelectric properties from first principles remains a challenging endeavor [J. Carrete et al., Phys. Rev. X 4, 011019 (2014)], and experimental researchers generally do not directly use computation to drive their own synthesis efforts. To bridge this practical gap between experimental needs and computational tools, we report an open machine learning-based recommendation engine (http://thermoelectrics.citrination.com) for materials researchers that suggests promising new thermoelectric compositions based on pre-screening about 25 000 known materials and also evaluates the feasibility of user-designed compounds. We show this engine can identify interesting chemistries very different from known thermoelectrics. Specifically, we describe the experimental characterization of one example set of compounds derived from our engine, RE12Co5Bi (RE = Gd, Er), which exhibits surprising thermoelectric performance given its unprecedentedly high loading with metallic d and f block elements and warrants further investigation as a new thermoelectric material platform. We show that our engine predicts this family of materials to have low thermal and high electrical conductivities, but modest Seebeck coefficient, all of which are confirmed experimentally. We note that the engine also predicts materials that may simultaneously optimize all three properties entering into zT; we selected RE12Co5Bi for this study due to its interesting chemical composition and known facile synthesis.

Stent-based delivery of adeno-associated viral vectors with sustained vascular transduction and iNOS-mediated inhibition of in-stent restenosis

PubMed Central

Fishbein, Ilia; Guerrero, David T.; Alferiev, Ivan S.; Foster, Jonathan B.; Minutolo, Nicholas G.; Chorny, Michael; Mas Monteys, Alejandro; Driesbaugh, Kathryn H.; Nagaswami, Chandrasekaran; Levy, Robert J.

2017-01-01

In-stent restenosis remains an important clinical problem in the era of drug eluting stents. Development of clinical gene therapy protocols for the prevention and treatment of in-stent restenosis is hampered by the lack of adequate local delivery systems. Herein we describe a novel stent-based gene delivery platform capable of providing local arterial gene transfer with adeno-associated viral (AAV) vectors. This system exploits the natural affinity of protein G (PrG) to bind to the Fc region of mammalian IgG, making PrG a universal adaptor for surface immobilization of vector-capturing antibodies (Ab). Our results: 1) demonstrate the feasibility of reversible immobilization of AAV2 vectors using vector tethering by AAV2-specific Ab appended to the stent surface through covalently attached PrG, 2) show sustained release kinetics of PrG/Ab-immobilized AAV2 vector particles into simulated physiological medium in vitro and site-specific transduction of cultured cells, 3) provide evidence of long-term (12 weeks) arterial expression of luciferase with PrG/Ab-tethered AAV2Luc, and 4) show anti-proliferative activity and anti-restenotic efficacy of stent-immobilized AAV2iNOS in the rat carotid artery model of stent angioplasty. PMID:28832561

The Potential Cost-Effectiveness of Pre-Exposure Prophylaxis Combined with HIV Vaccines in the United States.

PubMed

Adamson, Blythe J S; Carlson, Josh J; Kublin, James G; Garrison, Louis P

2017-05-24

This economic evaluation aims to support policy-making on the combined use of pre-exposure prophylaxis (PrEP) with HIV vaccines in development by evaluating the potential cost-effectiveness of implementation that would support the design of clinical trials for the assessment of combined product safety and efficacy. The target study population is a cohort of men who have sex with men (MSM) in the United States. Policy strategies considered include standard HIV prevention, daily oral PrEP, HIV vaccine, and their combination. We constructed a Markov model based on clinical trial data and the published literature. We used a payer perspective, monthly cycle length, a lifetime horizon, and a 3% discount rate. We assumed a price of $500 per HIV vaccine series in the base case. HIV vaccines dominated standard care and PrEP. At current prices, PrEP was not cost-effective alone or in combination. A combination strategy had the greatest health benefit but was not cost-effective (ICER = $463,448/QALY) as compared to vaccination alone. Sensitivity analyses suggest a combination may be valuable for higher-risk men with good adherence. Vaccine durability and PrEP drug prices were key drivers of cost-effectiveness. The results suggest that boosting potential may be key to HIV vaccine value.

Stereotypical hand movements in 144 subjects with Rett syndrome from the population-based Australian database.

PubMed

Carter, Philippa; Downs, Jenny; Bebbington, Ami; Williams, Simon; Jacoby, Peter; Kaufmann, Walter E; Leonard, Helen

2010-02-15

Stereotypic hand movements are a feature of Rett Syndrome but few studies have observed their nature systematically. Video data in familiar settings were obtained on subjects (n = 144) identified from an Australian population-based database. Hand stereotypies were demonstrated by most subjects (94.4%), 15 categories were observed and midline wringing was seen in approximately 60% of subjects. There was a median of two stereotypies per subject but this number decreased with age. Clapping and mouthing of hands were more prevalent in girls younger than 8 years and wringing was more prevalent in women 19 years or older. Clapping was commoner in those with p.R306C and early truncating mutations, and much rarer in those with p.R106W, p.R270X, p.R168X, and p.R255X. Stereotypies tended to be less frequent in those with more severe mutations. Otherwise, there were no clear relationships between our categories of stereotypies and mutation. Approximately a quarter each had predominantly right and left handed stereotypies and for the remaining half, no clear laterality was seen. Results were similar for all cases and when restricted to those with a pathogenic mutation. Hand stereotypies changed with increasing age but limited relationships with MECP2 mutations were identified. (c) 2009 Movement Disorder Society.

The Potential Cost-Effectiveness of Pre-Exposure Prophylaxis Combined with HIV Vaccines in the United States

PubMed Central

Adamson, Blythe J. S.; Carlson, Josh J.; Kublin, James G.; Garrison, Louis P.

2017-01-01

This economic evaluation aims to support policy-making on the combined use of pre-exposure prophylaxis (PrEP) with HIV vaccines in development by evaluating the potential cost-effectiveness of implementation that would support the design of clinical trials for the assessment of combined product safety and efficacy. The target study population is a cohort of men who have sex with men (MSM) in the United States. Policy strategies considered include standard HIV prevention, daily oral PrEP, HIV vaccine, and their combination. We constructed a Markov model based on clinical trial data and the published literature. We used a payer perspective, monthly cycle length, a lifetime horizon, and a 3% discount rate. We assumed a price of $500 per HIV vaccine series in the base case. HIV vaccines dominated standard care and PrEP. At current prices, PrEP was not cost-effective alone or in combination. A combination strategy had the greatest health benefit but was not cost-effective (ICER = $463,448/QALY) as compared to vaccination alone. Sensitivity analyses suggest a combination may be valuable for higher-risk men with good adherence. Vaccine durability and PrEP drug prices were key drivers of cost-effectiveness. The results suggest that boosting potential may be key to HIV vaccine value. PMID:28538691

Molecular Basis for the Relative Substrate Specificity of Human Immunodeficiency Virus Type 1 and Feline Immunodeficiency Virus Proteases

PubMed Central

Beck, Zachary Q.; Lin, Ying-Chuan; Elder, John H.

2001-01-01

We have used a random hexamer phage library to delineate similarities and differences between the substrate specificities of human immunodeficiency virus type 1 (HIV-1) and feline immunodeficiency virus (FIV) proteases (PRs). Peptide sequences were identified that were specifically cleaved by each protease, as well as sequences cleaved equally well by both enzymes. Based on amino acid distinctions within the P3-P3′ region of substrates that appeared to correlate with these cleavage specificities, we prepared a series of synthetic peptides within the framework of a peptide sequence cleaved with essentially the same efficiency by both HIV-1 and FIV PRs, Ac-KSGVF↓VVNGLVK-NH2 (arrow denotes cleavage site). We used the resultant peptide set to assess the influence of specific amino acid substitutions on the cleavage characteristics of the two proteases. The findings show that when Asn is substituted for Val at the P2 position, HIV-1 PR cleaves the substrate at a much greater rate than does FIV PR. Likewise, Glu or Gln substituted for Val at the P2′ position also yields peptides specifically susceptible to HIV-1 PR. In contrast, when Ser is substituted for Val at P1′, FIV PR cleaves the substrate at a much higher rate than does HIV-1 PR. In addition, Asn or Gln at the P1 position, in combination with an appropriate P3 amino acid, Arg, also strongly favors cleavage by FIV PR over HIV PR. Structural analysis identified several protease residues likely to dictate the observed specificity differences. Interestingly, HIV PR Asp30 (Ile-35 in FIV PR), which influences specificity at the S2 and S2′ subsites, and HIV-1 PR Pro-81 and Val-82 (Ile-98 and Gln-99 in FIV PR), which influence specificity at the S1 and S1′ subsites, are residues which are often involved in development of drug resistance in HIV-1 protease. The peptide substrate KSGVF↓VVNGK, cleaved by both PRs, was used as a template for the design of a reduced amide inhibitor, Ac-GSGVFΨ(CH2NH)VVNGL-NH2. This compound inhibited both FIV and HIV-1 PRs with approximately equal efficiency. These findings establish a molecular basis for distinctions in substrate specificity between human and feline lentivirus PRs and offer a framework for development of efficient broad-based inhibitors. PMID:11533208

A turn-on fluorescence chemosensor based on a tripodal amine [tris(pyrrolyl-α-methyl)amine]-rhodamine conjugate for the selective detection of zinc ions.

PubMed

Balamurugan, Rathinam; Chang, Wen-I; Zhang, Yandison; Fitriyani, Sri; Liu, Jui-Hsiang

2016-09-21

A novel tetradendate ligand derived from a tris(pyrrolyl-α-methyl)amine (H3tpa) and rhodamine-based conjugate (PR) has been designed for use as a sensor, synthesized and characterized spectroscopically. PR {(tris(5-rhodamineiminopyrrol-2-ylmethyl)amine)} serves as a selective colorimetric as well as a fluorescent chemosensor for Zn(2+) in acetonitrile/water (1 : 1, v/v). In the presence of Zn(2+), PR exhibited obvious absorption (558 nm) and emission (577 nm) peaks whose intensity increased along with increasing Zn(2+) concentrations. Titration experiments revealed that a large excess of Zn(2+) was required to saturate the absorption (λmax) and emission intensities. Upon the addition of 1000 equivalents of Zn(2+), the fluorescence intensity of the PR underwent an ∼500-fold increase (Φf = 0.34) with the emission maximum at 580 nm. These kinetics studies demonstrated that the absorption and emission changes were proportional to the Zn(2+) concentration. The color of the solution changed from colorless to a dark pink color. The fluorescence of the PR-Zn(2+) complex can be reversibly restored by using ammonium water or by heating. Competitive ion tests revealed that the intensity of PR-Zn(2+) was not suppressed by excess amounts of other metal ions. The counter anions did not exert obvious influences on the absorption and emission profiles. (1)H-NMR and FT-IR spectroscopic investigations of PR and PR-Zn(2+) revealed that the pyrrole motifs, -C[double bond, length as m-dash]N- groups and spirolactam of rhodamine B are capable of coordinating cation guest species. Because each arm of the tripodal ligand tautomerizes independently, only moderate fluorescence enhancement could be seen until all three -C[double bond, length as m-dash]N- groups were coordinated by zinc, which may be due to the spirolactam ring opening mechanism of the rhodamine unit. Once all three -C[double bond, length as m-dash]N- groups were locked by coordinating with excess of Zn(2+), the isomerization was arrested, and PR exhibited highly enhanced fluorescence. In addition, energy optimized structures of PR were found to be cage-like by Gaussian 09, further supporting that it can access a large excess of Zn(2+). Intriguingly, imaging of HeLa cells by using a confocal microscope revealed that this PR probe could be used for biological applications.

Determining the relative susceptibility of four prion protein genotypes to atypical scrapie

USDA-ARS?s Scientific Manuscript database

Atypical scrapie is a sheep prion (PrPSc) disease whose epidemiology is consistent with a sporadic origin and is associated with specific polymorphisms of the normal cellular prion protein (PrPC). We describe a mass spectrometry-based method of detecting and quantifying the polymorphisms of sheep P...

Paths to Upper Level Positions in Public Relations

ERIC Educational Resources Information Center

Bishop, Patrick J.

2010-01-01

Preparation for a career in the field of public relations (PR) is based on a set of unique core competencies typically found in liberal arts. Though PR professionals rarely gain business degrees, they acquire knowledge, skills, perspectives, and strategies well-suited to executive-level positions in business. Additionally, managerial positions in…

Healthcare Provider Contact and Pre-exposure Prophylaxis in Baltimore Men Who Have Sex With Men

PubMed Central

Raifman, Julia R.G.; Flynn, Colin; German, Danielle

2018-01-01

Introduction Pre-exposure prophylaxis (PrEP) safely and effectively prevents HIV in populations at high risk, including men who have sex with men (MSM). PrEP scale-up depends upon primary care providers and community-based organizations (CBOs) sharing PrEP information. This study aimed to determine whether healthcare provider or CBO contact was associated with PrEP awareness among Baltimore MSM. Methods This study used 2014 Baltimore MSM National HIV Behavioral Surveillance data, which included data on health care, HIV and sexually transmitted infection testing, and receipt of condoms from CBOs. In 2015, associations were estimated between healthcare contacts and PrEP awareness through logistic regression models controlling for age, race, and education and clustering by venue. Comparative analyses were conducted with HIV testing as outcome. Results There were 401 HIV-negative participants, of whom 168 (42%) were aware of PrEP. Visiting a healthcare provider in the past 12 months, receiving an HIV test from a provider, and having a sexually transmitted infection test in the past 12 months were not significantly associated with PrEP awareness. PrEP awareness was associated with being out to a healthcare provider (OR = 2.97, 95% CI=1.78, 4.96, p<0.001); being tested for HIV (OR=1.50, 95% CI = 1.06, 2.13, p = 0.023); and receiving condoms from an HIV/AIDS CBO (OR = 2.59, 95% CI = 1.43, 4.64, p = 0.001). By contrast, HIV testing was significantly associated with most forms of healthcare contact. Conclusions PrEP awareness is not associated with most forms of healthcare contact, highlighting the need for guidelines and trainings to support provider discussion of PrEP with MSM. PMID:27662698

A Multi-US City Assessment of Awareness and Uptake of Pre-exposure Prophylaxis (PrEP) for HIV Prevention Among Black Men and Transgender Women Who Have Sex with Men.

PubMed

Eaton, Lisa A; Matthews, Derrick D; Driffin, Daniel D; Bukowski, Leigh; Wilson, Patrick A; Stall, Ron D

2017-07-01

The HIV epidemic among Black men and transgender women who have sex with men (BMTW) demands an urgent public health response. HIV point prevalence among this population ranges from 25 to 43%-a rate far exceeding any other group. Pre-exposure prophylaxis (PrEP) for HIV prevention is a very promising prevention tool; however, its full potential to slow the epidemic has yet to be realized. For the current study, random time-location sampling at Black Gay Pride Events was used to collect data from N = 1274 BMTW, from five US cities, reporting HIV-negative/unknown status. In-field HIV testing was also provided to participants. Participants were assessed on awareness and use of PrEP, health care factors, HIV testing history, psychosocial variables, and sex behaviors. About one third of participants were aware of PrEP (39%), and a small percentage of participants were users of PrEP (4.6%). In multivariable analyses, being in a relationship, testing for HIV in the past 6 months, and others being aware of one's sexuality were positively associated with PrEP awareness. Higher levels of internalized homophobia and greater numbers of female sex partners were positively associated with PrEP use, while education and condom use were negatively associated. Based on study findings, messaging and uptake of PrEP needs greater expansion and requires novel approaches for scale-up. Improving linkage to HIV testing services is likely critical for engaging BMTW with PrEP. The potential for PrEP to slow the HIV epidemic is high; however, we must strengthen efforts to ensure universal availability and uptake.

Cost-Effectiveness of Pre-exposure HIV Prophylaxis During Pregnancy and Breastfeeding in Sub-Saharan Africa

PubMed Central

Wheeler, Stephanie B.; Stranix-Chibanda, Lynda; Hosek, Sybil G.; Watts, D. Heather; Siberry, George K.; Spiegel, Hans M. L.; Stringer, Jeffrey S.; Chi, Benjamin H.

2016-01-01

Introduction: Antiretroviral pre-exposure prophylaxis (PrEP) for the prevention of HIV acquisition is cost-effective when delivered to those at substantial risk. Despite a high incidence of HIV infection among pregnant and breastfeeding women in sub-Saharan Africa (SSA), a theoretical increased risk of preterm birth on PrEP could outweigh the HIV prevention benefit. Methods: We developed a decision analytic model to evaluate a strategy of daily oral PrEP during pregnancy and breastfeeding in SSA. We approached the analysis from a health care system perspective across a lifetime time horizon. Model inputs were derived from existing literature and local sources. The incremental cost-effectiveness ratio (ICER) of PrEP versus no PrEP was calculated in 2015 U.S. dollars per disability-adjusted life year (DALY) averted. We evaluated the effect of uncertainty in baseline estimates through one-way and probabilistic sensitivity analyses. Results: PrEP administered to pregnant and breastfeeding women in SSA was cost-effective. In a base case of 10,000 women, the administration of PrEP averted 381 HIV infections but resulted in 779 more preterm births. PrEP was more costly per person ($450 versus $117), but resulted in fewer disability-adjusted life years (DALYs) (3.15 versus 3.49). The incremental cost-effectiveness ratio of $965/DALY averted was below the recommended regional threshold for cost-effectiveness of $6462/DALY. Probabilistic sensitivity analyses demonstrated robustness of the model. Conclusions: Providing PrEP to pregnant and breastfeeding women in SSA is likely cost-effective, although more data are needed about adherence and safety. For populations at high risk of HIV acquisition, PrEP may be considered as part of a broader combination HIV prevention strategy. PMID:27355502

A Comprehensive Program to Reduce Rates of Hospital-Acquired Pressure Ulcers in a System of Community Hospitals.

PubMed

Englebright, Jane; Westcott, Ruth; McManus, Kathryn; Kleja, Kacie; Helm, Colleen; Korwek, Kimberly M; Perlin, Jonathan B

2018-03-01

The prevention of hospital-acquired pressure ulcers (PrUs) has significant consequences for patient outcomes and the cost of care. Providers are challenged with evaluating available evidence and best practices, then implementing programs and motivating change in various facility environments. In a large system of community hospitals, the Reducing Hospital Acquired-PrUs Program was developed to provide a toolkit of best practices, timely and appropriate data for focusing efforts, and continuous implementation support. Baseline data on PrU rates helped focus efforts on the most vulnerable patients and care situations. Facilities were empowered to use and adapt available resources to meet local needs and to share best practices for implementation across the system. Outcomes were measured by the rate of hospital-acquired PrUs, as gathered from patient discharge records. The rate of hospital-acquired stage III and IV PrUs decreased 66.3% between 2011 and 2013. Of the 149 participating facilities, 40 (27%) had zero hospital-acquired stage III and IV PrUs and 77 (52%) had a reduction in their PrU rate. Rates of all PrUs documented as present on admission did not change during this period. A comparison of different strategies used by the most successful facilities illustrated the necessity of facility-level flexibility and recognition of local workflows and patient demographics. Driven by the combination of a repository of evidence-based tools and best practices, readily available data on PrU rates, and local flexibility with processes, the Reducing Hospital Acquired-PrUs Program represents the successful operationalization of improvement in a wide variety of facilities.

The Effect of PrEP on HIV Incidence Among Men Who Have Sex With Men in the Context of Condom Use, Treatment as Prevention, and Seroadaptive Practices.

PubMed

LeVasseur, Michael T; Goldstein, Neal D; Tabb, Loni P; Olivieri-Mui, Brianne L; Welles, Seth L

2018-01-01

HIV preexposure prophylaxis (PrEP) is an effective tool in preventing HIV infection among high-risk men who have sex with men (MSM). It is unknown how effective PrEP is in the context of other implemented HIV prevention strategies, including condom use, seroadaption, and treatment as prevention (TasP). We evaluate the impact of increasing uptake of PrEP in conjunction with established prevention strategies on HIV incidence in a high-risk population of MSM through simulation. Agent-based simulation models representing the sexual behavior of high-risk, urban MSM in the United States over the period of 1 year were used to evaluate the effect of PrEP on HIV infection rates. Simulations included data for 10,000 MSM and compared increasing rates of PrEP uptake under 8 prevention paradigms: no additional strategies, TasP, condom use, seroadaptive behavior, and combinations thereof. We observed a mean of 103.2 infections per 10,000 MSM in the absence of any prevention method. PrEP uptake at 25% without any additional prevention strategies prevented 30.7% of infections. In the absence of PrEP, TasP, condom use, and seroadaptive behavior independently prevented 27.1%, 48.8%, and 37.7% of infections, respectively, and together prevented 72.2%. The addition of PrEP to the 3 aforementioned prevention methods, at 25% uptake, prevented an additional 5.0% of infections. To achieve a 25% reduction in HIV infections by 2020, HIV prevention efforts should focus on significantly scaling up access to PrEP in addition to HIV testing, access to antiretroviral therapy, and promoting condom use.

A visual dual-aptamer logic gate for sensitive discrimination of prion diseases-associated isoform with reusable magnetic microparticles and fluorescence quantum dots.

PubMed

Xiao, Sai Jin; Hu, Ping Ping; Chen, Li Qiang; Zhen, Shu Jun; Peng, Li; Li, Yuan Fang; Huang, Cheng Zhi

2013-01-01

Molecular logic gates, which have attracted increasing research interest and are crucial for the development of molecular-scale computers, simplify the results of measurements and detections, leaving the diagnosis of disease either "yes" or "no". Prion diseases are a group of fatal neurodegenerative disorders that happen in human and animals. The main problem with a diagnosis of prion diseases is how to sensitively and selectively discriminate and detection of the minute amount of PrP(Res) in biological samples. Our previous work had demonstrated that dual-aptamer strategy could achieve highly sensitive and selective discrimination and detection of prion protein (cellular prion protein, PrP(C), and the diseases associated isoform, PrP(Res)) in serum and brain. Inspired by the advantages of molecular logic gate, we further conceived a new concept for dual-aptamer logic gate that responds to two chemical input signals (PrP(C) or PrP(Res) and Gdn-HCl) and generates a change in fluorescence intensity as the output signal. It was found that PrP(Res) performs the "OR" logic operation while PrP(C) performs "XOR" logic operation when they get through the gate consisted of aptamer modified reusable magnetic microparticles (MMPs-Apt1) and quantum dots (QDs-Apt2). The dual-aptamer logic gate simplifies the discrimination results of PrP(Res), leaving the detection of PrP(Res) either "yes" or "no". The development of OR logic gate based on dual-aptamer strategy and two chemical input signals (PrP(Res) and Gdn-HCl) is an important step toward the design of prion diseases diagnosis and therapy systems.

Resistance to fracture of roots filled with different sealers.

PubMed

Sağsen, Burak; Ustün, Yakup; Pala, Kanşad; Demırbuğa, Sezer

2012-01-01

The aim of this study was to compare the fracture resistance of roots filled with gutta percha (GP) and different root canal sealers.Fifty-five human maxillary central incisors were selected and randomly divided into three experimental groups (Groups 1-3) and two control groups (Groups 4 and 5). They were Group 1-15 root canals filled with an epoxy resin-based sealer (AH Plus) and GP, Group 2 -15 root canals filled with a calcium silicate-based sealer (iRoot SP) and GP, Group 3: 15 root canals filled with another calcium silicate-based sealer (MTA Fillapex) and GP, Group 4: five roots were instrumented but not filled, and Group 5: five roots were neither instrumented nor filled. Compressive loading was carried out using a universal testing machine until fracture occurred. Force applied at time of fracture was recorded as fracture strength of specimen in Newtons. There were no significant differences in fracture strength among the three experimental groups (p>0.05), whose results were significantly superior to that of Group 4 (p<0.05). In conclusion, all the root canal sealers used in the present study increased the fracture resistance of instrumented root canals.

How landmark suitability shapes recognition memory signals for objects in the medial temporal lobes.

PubMed

Martin, Chris B; Sullivan, Jacqueline A; Wright, Jessey; Köhler, Stefan

2018-02-01

A role of perirhinal cortex (PrC) in recognition memory for objects has been well established. Contributions of parahippocampal cortex (PhC) to this function, while documented, remain less well understood. Here, we used fMRI to examine whether the organization of item-based recognition memory signals across these two structures is shaped by object category, independent of any difference in representing episodic context. Guided by research suggesting that PhC plays a critical role in processing landmarks, we focused on three categories of objects that differ from each other in their landmark suitability as confirmed with behavioral ratings (buildings > trees > aircraft). Participants made item-based recognition-memory decisions for novel and previously studied objects from these categories, which were matched in accuracy. Multi-voxel pattern classification revealed category-specific item-recognition memory signals along the long axis of PrC and PhC, with no sharp functional boundaries between these structures. Memory signals for buildings were observed in the mid to posterior extent of PhC, signals for trees in anterior to posterior segments of PhC, and signals for aircraft in mid to posterior aspects of PrC and the anterior extent of PhC. Notably, item-based memory signals for the category with highest landmark suitability ratings were observed only in those posterior segments of PhC that also allowed for classification of landmark suitability of objects when memory status was held constant. These findings provide new evidence in support of the notion that item-based memory signals for objects are not limited to PrC, and that the organization of these signals along the longitudinal axis that crosses PrC and PhC can be captured with reference to landmark suitability. Copyright © 2017 Elsevier Inc. All rights reserved.

Performance indicators for carrier-based DPIs: Carrier surface properties for capsule filling and API properties for in vitro aerosolisation.

PubMed

Faulhammer, E; Zellnitz, S; Wutscher, T; Stranzinger, S; Zimmer, A; Paudel, A

2018-01-30

This study investigates engineered carrier, as well as engineered API particles, and shows that there are distinct performance indicators of particle engineering for carrier-based dry powder inhalers (DPIs). Spray dried (SDSS) and jet-milled (JMSS) salbutamol sulphate (SS) was blended with untreated α-lactose monohydrate (LAC_R) and α-lactose monohydrate engineered (LAC_E). Subsequent capsule filling was performed with different process settings on a dosator nozzle capsule filling machine in order to reach a target fill weight of 20-25 mg. To evaluate the performance of the different mixtures, in vitro lung deposition experiments were carried out with a next generation impactor, the emitted dose (ED) and fine particle fraction (FPF) were calculated based on the specification of the European pharmacopoeia. The FPF of micronised powder blends is significantly higher (20%) compared to the FPF of spray dried blends (5%). Compared to API engineering, carrier engineering had a positive effect on the capsule filling performance (weight variability and mean fill weight) at lower compression ratios (setting 1). Results further showed that higher compression ratios appear to be beneficial in terms of capsule filling performance (higher fill weight and less fill weight variation). Concluding, it can be stated that the carrier engineering, or generally carrier properties, govern downstream processing, whereas the API engineering and API properties govern the aerosolisation performance and thereby significantly affect the dose delivery to the lungs. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of an Assay for the Detection of PrPres in Blood and Urine Based on PMCA Assay an ELISA Methods

DTIC Science & Technology

2005-09-01

constitute the basis for a TSE diagnostic human plasma assay platform. We have established a collaboration with Biotraces to develop an assay based on...their MPD instrument. One of the problems with the Biotraces ’ test was its inability to detect low levels of recombinant PrP. Biotraces has now succeeded...data and decide based on these new results whether to continue the collaboration with Biotraces . As soon we have reached a decision, we will inform

Reversible 1,2-Addition of Water To Form a Nucleophilic Mn(I) Hydroxide Complex: A Thermodynamic and Reactivity Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tondreau, Aaron M.; Michalczyk, Ryszard; Boncella, James M.

( iPrPN HP)Mn(CO) 2(OH) (2; iPrPN HP = HN{CH 2CH 2(P iPr 2)} 2) was formed from the reversible 1,2-addition of water to ( iPrPNP)Mn(CO) 2 (1; iPrPNP = the deprotonated, amide form of the ligand, –N{CH 2CH 2(P iPr 2)} 2). This reversible reaction was probed via variable-temperature NMR experiments, and the energetics of the 1,2-addition/elimination was found to be slightly exothermic (-0.8 kcal/mol). The corresponding manganese hydroxide was found to react with aldehydes, yielding the corresponding manganese carboxylate complexes ( iPrPN HP)Mn(CO) 2(CO 2R), where R = H, methyl, phenyl. While no reaction between 1 and neat benzaldehydemore » was observed, in the presence of water, conversion to the corresponding manganese-bound benzoate with formation of H 2 was observed. The catalytic oxidation of benzaldehyde by water without additives was unsuccessful due to strong product inhibition, with the manganese benzoate formed under a variety of reaction conditions. Upon addition of base, a catalytic cycle for the conversion of aldehyde to carboxylate and hydrogen can be devised.« less

Microsecond Unfolding Kinetics of Sheep Prion Protein Reveals an Intermediate that Correlates with Susceptibility to Classical Scrapie

PubMed Central

Chen, Kai-Chun; Xu, Ming; Wedemeyer, William J.; Roder, Heinrich

2011-01-01

The microsecond folding and unfolding kinetics of ovine prion proteins (ovPrP) were measured under various solution conditions. A fragment comprising residues 94–233 of the full-length ovPrP was studied for four variants with differing susceptibilities to classical scrapie in sheep. The observed biexponential unfolding kinetics of ovPrP provides evidence for an intermediate species. However, in contrast to previous results for human PrP, there is no evidence for an intermediate under refolding conditions. Global analysis of the kinetic data, based on a sequential three-state mechanism, quantitatively accounts for all folding and unfolding data as a function of denaturant concentration. The simulations predict that an intermediate accumulates under both folding and unfolding conditions, but is observable only in unfolding experiments because the intermediate is optically indistinguishable from the native state. The relative population of intermediates in two ovPrP variants, both transiently and under destabilizing equilibrium conditions, correlates with their propensities for classical scrapie. The variant susceptible to classical scrapie has a larger population of the intermediate state than the resistant variant. Thus, the susceptible variant should be favored to undergo the PrPC to PrPSc conversion and oligomerization. PMID:21889460

Reversible 1,2-Addition of Water To Form a Nucleophilic Mn(I) Hydroxide Complex: A Thermodynamic and Reactivity Study

DOE PAGES

Tondreau, Aaron M.; Michalczyk, Ryszard; Boncella, James M.

2017-09-20

( iPrPN HP)Mn(CO) 2(OH) (2; iPrPN HP = HN{CH 2CH 2(P iPr 2)} 2) was formed from the reversible 1,2-addition of water to ( iPrPNP)Mn(CO) 2 (1; iPrPNP = the deprotonated, amide form of the ligand, –N{CH 2CH 2(P iPr 2)} 2). This reversible reaction was probed via variable-temperature NMR experiments, and the energetics of the 1,2-addition/elimination was found to be slightly exothermic (-0.8 kcal/mol). The corresponding manganese hydroxide was found to react with aldehydes, yielding the corresponding manganese carboxylate complexes ( iPrPN HP)Mn(CO) 2(CO 2R), where R = H, methyl, phenyl. While no reaction between 1 and neat benzaldehydemore » was observed, in the presence of water, conversion to the corresponding manganese-bound benzoate with formation of H 2 was observed. The catalytic oxidation of benzaldehyde by water without additives was unsuccessful due to strong product inhibition, with the manganese benzoate formed under a variety of reaction conditions. Upon addition of base, a catalytic cycle for the conversion of aldehyde to carboxylate and hydrogen can be devised.« less

An Official American Thoracic Society/European Respiratory Society Policy Statement: Enhancing Implementation, Use, and Delivery of Pulmonary Rehabilitation.

PubMed

Rochester, Carolyn L; Vogiatzis, Ioannis; Holland, Anne E; Lareau, Suzanne C; Marciniuk, Darcy D; Puhan, Milo A; Spruit, Martijn A; Masefield, Sarah; Casaburi, Richard; Clini, Enrico M; Crouch, Rebecca; Garcia-Aymerich, Judith; Garvey, Chris; Goldstein, Roger S; Hill, Kylie; Morgan, Michael; Nici, Linda; Pitta, Fabio; Ries, Andrew L; Singh, Sally J; Troosters, Thierry; Wijkstra, Peter J; Yawn, Barbara P; ZuWallack, Richard L

2015-12-01

Pulmonary rehabilitation (PR) has demonstrated physiological, symptom-reducing, psychosocial, and health economic benefits for patients with chronic respiratory diseases, yet it is underutilized worldwide. Insufficient funding, resources, and reimbursement; lack of healthcare professional, payer, and patient awareness and knowledge; and additional patient-related barriers all contribute to the gap between the knowledge of the science and benefits of PR and the actual delivery of PR services to suitable patients. The objectives of this document are to enhance implementation, use, and delivery of pulmonary rehabilitation to suitable individuals worldwide. Members of the American Thoracic Society (ATS) Pulmonary Rehabilitation Assembly and the European Respiratory Society (ERS) Rehabilitation and Chronic Care Group established a Task Force and writing committee to develop a policy statement on PR. The document was modified based on feedback from expert peer reviewers. After cycles of review and revisions, the statement was reviewed and formally approved by the Board of Directors of the ATS and the Science Council and Executive Committee of the ERS. This document articulates policy recommendations for advancing healthcare professional, payer, and patient awareness and knowledge of PR, increasing patient access to PR, and ensuring quality of PR programs. It also recommends areas of future research to establish evidence to support the development of an updated funding and reimbursement policy regarding PR. The ATS and ERS commit to undertake actions that will improve access to and delivery of PR services for suitable patients. They call on their members and other health professional societies, payers, patients, and patient advocacy groups to join in this commitment.

Contextual Facilitators of and Barriers to Nursing Home Pressure Ulcer Prevention

PubMed Central

Hartmann, Christine W.; Solomon, Jeffrey; Palmer, Jennifer A.; Lukas, Carol VanDeusen

2016-01-01

OBJECTIVE Important gaps exist in the knowledge of how to achieve successful, sustained prevention of pressure ulcers (PrUs) in nursing homes. This study aimed to address those gaps by comparing nursing leadership and indirect care staff members’ impressions about the context of PrU prevention in facilities with improving and declining PrU rates. SETTING The study was conducted in a sample of 6 Veterans Health Administration nursing homes (known as community living centers) purposively selected to represent a range of PrU care performance. DESIGN AND PARTICIPANTS One-time 30-minute semistructured interviews with 23 community living center staff were conducted. Qualitative interview data were analyzed using an analytic framework containing (a) a priori analytic constructs based on the study’s conceptual framework and (b) sections for emerging constructs. MAIN RESULTS Analysis revealed 6 key concepts differentiating sites with improving and declining PrU care performance. These concepts were (1) structures through which the change effort is initiated; (2) organizational prioritization, alignment, and support; (3) improvement culture; (4) clarity of roles and responsibilities; (5) communication strategies; and (6) staffing and clinical practices. Results also pointed to potential contextual facilitators of and barriers to successful PrU prevention. CONCLUSIONS Leadership’s visible prioritization of and support for PrU prevention and the initiation of PrU prevention activities through formal structures were the most striking components represented at sites with improving performance, but not at ones where performance declined. Sites with improving performance were more likely to align frontline staff and leadership goals for PrU prevention. PMID:27089151

Synthesis of Surface-Analogue Square-Planar Tetranuclear Nickel Hydride Clusters and Bonding to μ4-NR, -O and -BH Ligands.

PubMed

Shoshani, Manar M; Beck, Robert; Wang, Xiaoping; McLaughlin, Matthew J; Johnson, Samuel A

2018-03-05

Tetranuclear Ni complexes were synthesized with bonding to BH, NR, and O in atypical surface-like geometries. The previously reported electron-deficient cluster [( i Pr 3 P)Ni] 5 H 6 (1) reacts with N-methylmorpholine oxide to give [( i Pr 3 P)Ni] 4 H 4 (μ 4 -O) (2), which contains O coordinated in the center of a square-plane arrangement of Ni atoms. Reaction of 1 with benzonitrile gave the square-planar tetranuclear Ni cluster [( i Pr 3 P)Ni] 4 H 4 (μ 4 -NCH 2 Ph) (3), which contains an imido donor in a square-based-pyramidal geometry. This reaction also gives [( i Pr 3 P)Ni(N≡CPh)] 3 (4), with bridging benzonitrile ligands. Trimer 4 was independently synthesized from the reaction of Ni(COD) 2 , i Pr 3 P, and PhC≡N. The addition of dihydrogen to a 1:1 mixture of [( i Pr 3 P) 2 Ni] 2 (N 2 ) and ( i Pr 3 P) 2 NiCl 2 yielded [( i Pr 3 P)Ni] 4 (μ 3 -H) 4 (μ 2 -Cl) 2 (5), with a tetrahedral Ni core, in contrast to the square-planar geometries of 2 and 3. The solid-state structure of 5 was determined using both X-ray and neutron diffraction. Reaction of 5 with LiBH 4 gave [( i Pr 3 P)Ni] 4 H 4 (μ 4 -BH) 2 ] (6) via loss of LiCl and H 2 .

Development of a design space and predictive statistical model for capsule filling of low-fill-weight inhalation products.

PubMed

Faulhammer, E; Llusa, M; Wahl, P R; Paudel, A; Lawrence, S; Biserni, S; Calzolari, V; Khinast, J G

2016-01-01

The objectives of this study were to develop a predictive statistical model for low-fill-weight capsule filling of inhalation products with dosator nozzles via the quality by design (QbD) approach and based on that to create refined models that include quadratic terms for significant parameters. Various controllable process parameters and uncontrolled material attributes of 12 powders were initially screened using a linear model with partial least square (PLS) regression to determine their effect on the critical quality attributes (CQA; fill weight and weight variability). After identifying critical material attributes (CMAs) and critical process parameters (CPPs) that influenced the CQA, model refinement was performed to study if interactions or quadratic terms influence the model. Based on the assessment of the effects of the CPPs and CMAs on fill weight and weight variability for low-fill-weight inhalation products, we developed an excellent linear predictive model for fill weight (R(2 )= 0.96, Q(2 )= 0.96 for powders with good flow properties and R(2 )= 0.94, Q(2 )= 0.93 for cohesive powders) and a model that provides a good approximation of the fill weight variability for each powder group. We validated the model, established a design space for the performance of different types of inhalation grade lactose on low-fill weight capsule filling and successfully used the CMAs and CPPs to predict fill weight of powders that were not included in the development set.

Potential of scrap tire rubber as lightweight aggregate in flowable fill.

PubMed

Pierce, C E; Blackwell, M C

2003-01-01

Flowable fill is a self-leveling and self-compacting material that is rapidly gaining acceptance and application in construction, particularly in transportation and utility earthworks. When mixed with concrete sand, standard flowable fill produces a mass density ranging from 1.8 to 2.3 g/cm(3) (115-145 pcf). Scrap tires can be granulated to produce crumb rubber, which has a granular texture and ranges in size from very fine powder to coarse sand-sized particles. Due to its low specific gravity, crumb rubber can be considered a lightweight aggregate. This paper describes an experimental study on replacing sand with crumb rubber in flowable fill to produce a lightweight material. To assess the technical feasibility of using crumb rubber, the fluid- and hardened-state properties of nine flowable fill mixtures were measured. Mixture proportions were varied to investigate the effects of water-to-cement ratio and crumb rubber content on fill properties. Experimental results indicate that crumb rubber can be successfully used to produce a lightweight flowable fill (1.2-1.6 g/cm(3) [73-98 pcf]) with excavatable 28-day compressive strengths ranging from 269 to 1194 kPa (39-173 psi). Using a lightweight fill reduces the applied stress on underlying soils, thereby reducing the potential for bearing capacity failure and minimizing soil settlement. Based on these results, a crumb rubber-based flowable fill can be used in a substantial number of construction applications, such as bridge abutment fills, trench fills, and foundation support fills.

Hugoniot-based equations of state for two filled EPDM rubbers

NASA Astrophysics Data System (ADS)

Pacheco, Adam; Dattelbaum, Dana; Orler, E.; Gustavsen, R.

2013-06-01

The shock response of silica filled and Kevlar filled ethylene-propylene-diene (EPDM) rubbers was studied using gas gun-driven plate impact experiments. Both materials are proprietary formulations made by Kirkhill-TA, Brea CA USA, and are used for ablative internal rocket motor insulation. Two types of experiments were performed. In the first, the filled-EPDM sample was mounted on the front of the projectile and impacted a Lithium Fluoride (LiF) window. The Hugoniot state was determined from the measured projectile velocity, the EPDM/LiF interface velocity (measured using VISAR) and impedance matching to LiF. In the second type of experiment, electromagnetic particle velocity gauges were embedded between layers of filled-EPDM. These provided in situ particle velocity and shock velocity measurements. Experiments covered a pressure range of 0.34 - 14 GPa. Hugoniot-based equations of state were obtained for both materials, and will be compared to those of other filled elastomers such as silica-filled polydimethylsiloxane and adiprene. Work performed while at Los Alamos National Laboratory.

PR Toxin – Biosynthesis, Genetic Regulation, Toxicological Potential, Prevention and Control Measures: Overview and Challenges

PubMed Central

Dubey, Manish K.; Aamir, Mohd; Kaushik, Manish S.; Khare, Saumya; Meena, Mukesh; Singh, Surendra; Upadhyay, Ram S.

2018-01-01

Out of the various mycotoxigenic food and feed contaminant, the fungal species belonging to Penicillium genera, particularly Penicillium roqueforti is of great economic importance, and well known for its crucial role in the manufacturing of Roquefort and Gorgonzola cheese. The mycotoxicosis effect of this mold is due to secretion of several metabolites, of which PR toxin is of considerable importance, with regard to food quality and safety challenges issues. The food products and silages enriched with PR toxin could lead into damage to vital internal organs, gastrointestinal perturbations, carcinogenicity, immunotoxicity, necrosis, and enzyme inhibition. Moreover, it also has the significant mutagenic potential to disrupt/alter the crucial processes like DNA replication, transcription, and translation at the molecular level. The high genetic diversities in between the various strains of P. roqueforti persuaded their nominations with Protected Geographical Indication (PGI), accordingly to the cheese type, they have been employed. Recently, the biosynthetic mechanism and toxicogenetic studies unraveled the role of ari1 and prx gene clusters that cross-talk with the synthesis of other metabolites or involve other cross-regulatory pathways to negatively regulate/inhibit the other biosynthetic route targeted for production of a strain-specific metabolites. Interestingly, the chemical conversion that imparts toxic properties to PR toxin is the substitution/oxidation of functional hydroxyl group (-OH) to aldehyde group (-CHO). The rapid conversion of PR toxin to the other derivatives such as PR imine, PR amide, and PR acid, based on conditions available reflects their unstability and degradative aspects. Since the PR toxin-induced toxicity could not be eliminated safely, the assessment of dose-response and other pharmacological aspects for its safe consumption is indispensable. The present review describes the natural occurrences, diversity, biosynthesis, genetics, toxicological aspects, control and prevention strategies, and other management aspects of PR toxin with paying special attention on economic impacts with intended legislations for avoiding PR toxin contamination with respect to food security and other biosafety purposes. PMID:29651243

Calcium binding promotes prion protein fragment 90-231 conformational change toward a membrane destabilizing and cytotoxic structure.

PubMed

Sorrentino, Sacha; Bucciarelli, Tonino; Corsaro, Alessandro; Tosatto, Alessio; Thellung, Stefano; Villa, Valentina; Schininà, M Eugenia; Maras, Bruno; Galeno, Roberta; Scotti, Luca; Creati, Francesco; Marrone, Alessandro; Re, Nazzareno; Aceto, Antonio; Florio, Tullio; Mazzanti, Michele

2012-01-01

The pathological form of prion protein (PrP(Sc)), as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrP(Sc) extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90-231 (hPrP₉₀₋₂₃₁) increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrP(Sc). In the present study we demonstrate that hPrP₉₀₋₂₃₁, pre-incubated with 10 mM Ca⁺⁺ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP₉₀₋₂₃₁ bearing pathogenic mutations (D202N and E200K). We also report that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP₉₀₋₂₃₁ cytotoxicity. Finally, by in silico structural analysis, we propose that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity.

Calcium Binding Promotes Prion Protein Fragment 90–231 Conformational Change toward a Membrane Destabilizing and Cytotoxic Structure

PubMed Central

Corsaro, Alessandro; Tosatto, Alessio; Thellung, Stefano; Villa, Valentina; Schininà, M. Eugenia; Maras, Bruno; Galeno, Roberta; Scotti, Luca; Creati, Francesco; Marrone, Alessandro; Re, Nazzareno; Aceto, Antonio; Florio, Tullio; Mazzanti, Michele

2012-01-01

The pathological form of prion protein (PrPSc), as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrPSc extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90–231 (hPrP90–231) increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrPSc. In the present study we demonstrate that hPrP90–231, pre-incubated with 10 mM Ca++ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP90–231 bearing pathogenic mutations (D202N and E200K). We also report that Ca++ binding to hPrP90–231 induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP90–231 cytotoxicity. Finally, by in silico structural analysis, we propose that Ca++ binding to hPrP90–231 modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity. PMID:22811758

Cost-effectiveness of the highly effective direct-acting antivirals in the treatment of chronic hepatitis C in Hong Kong.

PubMed

Lo, Angeline Oi-Shan; Chan, Henry Lik-Yuen; Wong, Vincent Wai-Sun; Wong, Grace Lai-Hung

2017-05-01

In Asia-Pacific where cost is a major concern, peginterferon plus ribavirin (PR) often remain as the standard of care in chronic hepatitis C (CHC) treatment, while the direct-acting antivirals (DAAs) are commonly recommended as retreatment. Newer DAAs can achieve a sustained virological response (SVR) of nearly 100% with pan-genotypic coverage, that is "Highly Effective DAAs." We aimed to investigate the most desirable cost range for the Highly Effective DAAs using Hong Kong as an example. Markov modeling was performed using PR as the reference strategy. The cost-effectiveness of the Highly Effective DAAs was compared with sofosbuvir-PR (first-line and rescue) and boceprevir-PR therapies. A 50-year-old genotype 1b hepatitis C virus (HCV) infected treatment-naïve patient with METAVIR F3 was used as the base case scenario to reflect the commonest HCV genotype in Hong Kong. The use of PR would incur a lifetime cost of US$35,854 and effectiveness of 14.85 quality-adjusted life-year (QALY). Sofosbuvir-PR as first-line treatment was dominated by other regimes. If Sofosbuvir-PR rescue therapy was used, the drug cost of Highly Effective DAAs should be set below US$43,553, with a cost-effectiveness ratio (CER) of US$3035/QALY compared with PR. In regions where Boceprevir-PR was still used as first-line therapy, the desirable drug cost of Highly Effective DAAs would be below US$56,985 to achieve a CER of US$5427/QALY. The most desirable costs of the Highly Effective DAAs would be below US$43,553 if Sofosbuvir-PR rescue therapy is used and below US$56,985 if Boceprevir-PR therapy is used. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

The future of PrEP among transgender women: the critical role of gender affirmation in research and clinical practices.

PubMed

Sevelius, Jae M; Deutsch, Madeline B; Grant, Robert

2016-01-01

Globally, transgender ("trans") women are one of the key populations most disproportionately impacted by HIV. Pre-exposure prophylaxis (PrEP) is the newest and most promising biomedical HIV prevention intervention to date. This paper reviews relevant literature to describe the current state of the science and describes the potential role of PrEP among trans women, including a discussion of unique considerations for maximizing the impact of PrEP for this vulnerable population. Available information, including but not limited to existing scientific literature, about trans women and PrEP was reviewed and critiqued based on author expertise, including PrEP clinical trials and rollout. To date, PrEP demonstration projects and clinical trials have largely excluded trans women, or have not included them in a meaningful way. Data collection strategies that fail to identify trans women in clinical trials and research further limit the ability to draw conclusions about trans women's unique needs and devise strategies to meet them. Gender-affirming providers and clinic environments are essential components of any sexual health programme that aims to serve trans women, as they will largely avoid settings that may result in stigmatizing encounters and threats to their identities. While there is currently no evidence to suggest drug-drug interactions between PrEP and commonly used feminizing hormone regimens, community concerns about potential interactions may limit interest in and uptake of PrEP among trans women. In scaling up PrEP for trans women, it is essential to engage trans communities, utilize trans-inclusive research and marketing strategies and identify and/or train healthcare providers to provide gender-affirming healthcare to trans women, including transition-related care such as hormone provision. PrEP implementation guidelines must consider and address trans women's unique barriers and facilitators to uptake and adherence.

Atom-replaced pins in a Y-based superconductor—single-crystalline perovskite structure including both PrBa2Cu3O7‑x and YBa2Cu3O7‑y

NASA Astrophysics Data System (ADS)

Hayashi, Mariko; Araki, Takeshi; Ishii, Hirotaka; Nishijima, Gen; Matsumoto, Akiyoshi

2018-05-01

Metal organic deposition using trifluoroacetates (TFA-MOD) provides many uniform superconductors on long metal tapes. The large numbers of long wires have been applied for power grids or superconducting fault current limiters. The related applications worked for a long time without fatal trouble. The quasi-liquid produced during the firing process assisted the perfectly uniform structure in TFA-MOD. On the other hand, when it was desired to introduce artificial pinning centers, the quasi-liquid also enlarged the diameter of the artificial pinning centers to several tens of nanometers. In other words, due to the nature of TFA-MOD, there is very little chance of using TFA-MOD to prepare several nm-sized artificial pinning centers. By proposing atom-replaced pins (ARPs), we aim to overcome the impasse. ARPs are realized by replacing yttrium (Y) with praseodymium (Pr) whose valence number changes from 3+ to approximately 4+. Analytical results suggested that Pr makes pinning centers on a PrBa2Cu3O7‑x (PrBCO) unit cell, and the weak-linked superconductivity derived from PrBCO extends to the adjacent unit cells in the a/b-plane. J c decrease by Pr is five times as large as the volume fraction of Pr in the Y-site of the perovskite structure. On the other hand, T c does not show large degradation in YBCO including 10% PrBCO. These results suggest that PrBCO unit cells are fully dispersed in YBa2Cu3O7‑y matrix. With regard to J c in the magnetic field, (Y0.98, Pr0.02)BCO has been slightly improved compared with pure YBCO only in the region of high temperature and low magnetic field of less than 1 T.

Winter precipitation characteristics in western US related to atmospheric river landfalls: observations and model evaluations

NASA Astrophysics Data System (ADS)

Kim, J.; Guan, B.; Waliser, D. E.; Ferraro, R. D.; Case, J. L.; Iguchi, T.; Kemp, E.; Putman, W.; Wang, W.; Wu, D.; Tian, B.

2018-01-01

Winter precipitation (PR) characteristics in western United States (WUS) related to atmospheric river (AR) landfalls are examined using the observation-based PRISM data. The observed AR-related precipitation characteristics are in turn used to evaluate model precipitation data from the NASA MERRA2 reanalysis and from seven dynamical downscaling simulations driven by the MERRA2. Multiple metrics including mean bias, Taylor diagram, and two skill scores are used to measure model performance for three climatological sub-regions in WUS, Pacific Northwest (PNW), Pacific Southwest (PSW) and Great Basin (GB). All model data well represent the winter-mean PR with spatial pattern correlations of 0.8 or higher with PRISM for the three sub-regions. Higher spatial resolutions and/or the use of spectral nudging generally yield higher skill scores in simulating the geographical distribution of PR for the entire winter. The PRISM data shows that the AR-related fraction of winter PR and associated daily PR PDFs in each region vary strongly for landfall locations; AR landfalls in the northern WUS coast (NC) affect mostly PNW while those in the southern WUS coast (SC) affect both PSW and GB. NC (SC) landfalls increase the frequency of heavy PR in PNW (PSW and GB) but reduce it in PSW (PNW). All model data reasonably represent these observed variations in the AR-related winter PR fractions and the daily PR PDFs according to AR landfall locations. However, unlike for the entire winter period, no systematic effects of resolution and/or spectral nudging are identified in these AR-related PR characteristics. Dynamical downscaling in this study generally yield positive added values to the MERRA2 PR in the AR-related PR fraction for most sub-regions and landfall locations, most noticeably for PSW by NU-WRF. The downscaling also generate positive added value in p95 for PNW, but negative values for PSW and GB due to overestimation of heavy precipitation events.

Introducing a Rigid Loop Structure from Deer into Mouse Prion Protein Increases Its Propensity for Misfolding In Vitro

PubMed Central

Kyle, Leah M.; John, Theodore R.; Schätzl, Hermann M.; Lewis, Randolph V.

2013-01-01

Prion diseases are fatal neurodegenerative disorders characterized by misfolding of the cellular prion protein (PrPc) into the disease-associated isoform (PrPSc) that has increased β-sheet content and partial resistance to proteolytic digestion. Prion diseases from different mammalian species have varying propensities for transmission upon exposure of an uninfected host to the infectious agent. Chronic Wasting Disease (CWD) is a highly transmissible prion disease that affects free ranging and farmed populations of cervids including deer, elk and moose, as well as other mammals in experimental settings. The molecular mechanisms allowing CWD to maintain comparatively high transmission rates have not been determined. Previous work has identified a unique structural feature in cervid PrP, a rigid loop between β-sheet 2 and α-helix 2 on the surface of the protein. This study was designed to test the hypothesis that the rigid loop has a direct influence on the misfolding process. The rigid loop was introduced into murine PrP as the result of two amino acid substitutions: S170N and N174T. Wild-type and rigid loop murine PrP were expressed in E. coli and purified. Misfolding propensity was compared for the two proteins using biochemical techniques and cell free misfolding and conversion systems. Murine PrP with a rigid loop misfolded in cell free systems with greater propensity than wild type murine PrP. In a lipid-based conversion assay, rigid loop PrP converted to a PK resistant, aggregated isoform at lower concentrations than wild-type PrP. Using both proteins as substrates in real time quaking-induced conversion, rigid loop PrP adopted a misfolded isoform more readily than wild type PrP. Taken together, these findings may help explain the high transmission rates observed for CWD within cervids. PMID:23825561

Event-level analysis of alcohol consumption and condom use in partnership contexts among men who have sex with men and transgender women in Lima, Peru.

PubMed

Delgado, Jeanne R; Segura, Eddy R; Lake, Jordan E; Sanchez, Jorge; Lama, Javier R; Clark, Jesse L

2017-01-01

We explored the association between alcohol use and condomless receptive (CRAI) and insertive (CIAI) anal intercourse within partnership contexts of men who have sex with men (MSM) and transgender women (TGW) in Lima, Peru. From 2012-2014, we surveyed men and TGW (n=1607) who reported anal intercourse with ≥1 male or TGW. Alcohol use with up to 3 sexual partners during the prior 90days was evaluated. Bivariate and multivariate analyses used generalized estimating equations to assess event-level associations between alcohol use, CRAI, CIAI, and partnership characteristics while adjusting for participant clustering from multiple partners. Of 4774 sexual partnerships reported, 48% were casual, 34% primary, 10% anonymous, and 8% commercial. Alcohol use preceding sex was significantly (p<0.05) associated with CRAI (PR=1.26) and CIAI (PR=1.37). Partnership characteristics significantly associated with alcohol use included commercial sex work (PR=2.21) and trended (p<0.10) towards alcohol use with casual (PR=1.16), transgender (PR=1.48), and moderno ("versatile"; PR=1.17) partners. CRAI and CIAI were more common among participants who reported knowing they (PR=1.52; PR=1.41, respectively) or their partner (PR=1.47; PR=1.44, respectively) was HIV-uninfected. Yet, only CIAI (PR=1.42) was more commonly reported with known HIV-infected partners. Participants who drank alcohol prior to sex were less likely to know their partner's HIV serostatus. Alcohol use prior to intercourse was associated with CRAI and CIAI, varied by partnership type, and may impair knowledge of partner HIV serostatus. Detailed knowledge of alcohol use within partner-specific contexts is essential for informing condom-based and alternative HIV prevention strategies for MSM and TGW in Peru. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

PR Toxin - Biosynthesis, Genetic Regulation, Toxicological Potential, Prevention and Control Measures: Overview and Challenges.

PubMed

Dubey, Manish K; Aamir, Mohd; Kaushik, Manish S; Khare, Saumya; Meena, Mukesh; Singh, Surendra; Upadhyay, Ram S

2018-01-01

Out of the various mycotoxigenic food and feed contaminant, the fungal species belonging to Penicillium genera, particularly Penicillium roqueforti is of great economic importance, and well known for its crucial role in the manufacturing of Roquefort and Gorgonzola cheese. The mycotoxicosis effect of this mold is due to secretion of several metabolites, of which PR toxin is of considerable importance, with regard to food quality and safety challenges issues. The food products and silages enriched with PR toxin could lead into damage to vital internal organs, gastrointestinal perturbations, carcinogenicity, immunotoxicity, necrosis, and enzyme inhibition. Moreover, it also has the significant mutagenic potential to disrupt/alter the crucial processes like DNA replication, transcription, and translation at the molecular level. The high genetic diversities in between the various strains of P. roqueforti persuaded their nominations with Protected Geographical Indication (PGI), accordingly to the cheese type, they have been employed. Recently, the biosynthetic mechanism and toxicogenetic studies unraveled the role of ari1 and prx gene clusters that cross-talk with the synthesis of other metabolites or involve other cross-regulatory pathways to negatively regulate/inhibit the other biosynthetic route targeted for production of a strain-specific metabolites. Interestingly, the chemical conversion that imparts toxic properties to PR toxin is the substitution/oxidation of functional hydroxyl group (-OH) to aldehyde group (-CHO). The rapid conversion of PR toxin to the other derivatives such as PR imine, PR amide, and PR acid, based on conditions available reflects their unstability and degradative aspects. Since the PR toxin-induced toxicity could not be eliminated safely, the assessment of dose-response and other pharmacological aspects for its safe consumption is indispensable. The present review describes the natural occurrences, diversity, biosynthesis, genetics, toxicological aspects, control and prevention strategies, and other management aspects of PR toxin with paying special attention on economic impacts with intended legislations for avoiding PR toxin contamination with respect to food security and other biosafety purposes.

The future of PrEP among transgender women: the critical role of gender affirmation in research and clinical practices

PubMed Central

Sevelius, Jae M; Deutsch, Madeline B; Grant, Robert

2016-01-01

Introduction Globally, transgender (“trans”) women are one of the key populations most disproportionately impacted by HIV. Pre-exposure prophylaxis (PrEP) is the newest and most promising biomedical HIV prevention intervention to date. This paper reviews relevant literature to describe the current state of the science and describes the potential role of PrEP among trans women, including a discussion of unique considerations for maximizing the impact of PrEP for this vulnerable population. Methods Available information, including but not limited to existing scientific literature, about trans women and PrEP was reviewed and critiqued based on author expertise, including PrEP clinical trials and rollout. Results To date, PrEP demonstration projects and clinical trials have largely excluded trans women, or have not included them in a meaningful way. Data collection strategies that fail to identify trans women in clinical trials and research further limit the ability to draw conclusions about trans women's unique needs and devise strategies to meet them. Gender-affirming providers and clinic environments are essential components of any sexual health programme that aims to serve trans women, as they will largely avoid settings that may result in stigmatizing encounters and threats to their identities. While there is currently no evidence to suggest drug-drug interactions between PrEP and commonly used feminizing hormone regimens, community concerns about potential interactions may limit interest in and uptake of PrEP among trans women. Conclusions In scaling up PrEP for trans women, it is essential to engage trans communities, utilize trans-inclusive research and marketing strategies and identify and/or train healthcare providers to provide gender-affirming healthcare to trans women, including transition-related care such as hormone provision. PrEP implementation guidelines must consider and address trans women's unique barriers and facilitators to uptake and adherence. PMID:27760683

Biological degradation of gas-filled composite materials on the base of polyethylene

NASA Astrophysics Data System (ADS)

Grigoreva, E. A.; Kolesnikova, N. N.; Popov, A. A.; Olkhov, A. A.

2017-12-01

Gas-filled composite materials based on polyethylene were obtained. It was assumed that introduction of porosity in polyethylene will improve the biodegradability of synthetic materials. The morphological and structural changes were estimated, physical and mechanical properties, stability in water and soil of these materials were determined. It is stated that filling the polymer matrix with pores increases the ability to degrade in nature.

Boceprevir plus peginterferon/ribavirin for treatment of chronic hepatitis C in Russia.

PubMed

Isakov, Vasily; Nikitin, Igor; Chulanov, Vladimir; Ogurtsov, Pavel; Lukyanova, Ekaterina; Long, Jianmin; Wahl, Janice; Helmond, Frans A

2016-02-28

To evaluate addition of boceprevir to peginterferon/ribavirin (PR) in Russian patients with chronic hepatitis C virus (HCV). Treatment-naive (TN) and treatment-experienced (TE) patients (who had failed prior treatment with PR for ≥ 12 wk) with chronic HCV genotype 1 infection were enrolled in this placebo-controlled, double-blind study. All patients initially received PR for 4 wk. Patients randomized to control treatment then received PR for an additional 44 wk. TN patients randomized to triple therapy received boceprevir (800 mg three times daily) plus PR for 24 wk and then further therapy according to treatment week 8 (TW8) HCV RNA levels. TE patients received boceprevir plus PR for 32 wk and then further therapy according to TW8 HCV RNA levels. Treatment was discontinued for TN patients with detectable HCV RNA at TW24 and TE patients with detectable HCV RNA at TW12 because of futility. The primary efficacy end point was sustained virologic response (SVR) defined as undetectable HCV RNA 24 wk after completing all study therapy. SVR was 74.8% in the boceprevir plus PR arm compared with 46.2% in the control arm, with a stratification-adjusted treatment difference of 29.2% (95%CI: 16.4-41.5; P < 0.0001). Rates of SVR were higher in the boceprevir arm in both TN and TE patient groups (TN 78.4% vs 56.3%; TE 69.4% vs 30.0%). Within TE patients, the rates of SVR were higher with boceprevir plus PR compared with PR, regardless of treatment failure type (null responder, partial responder, and relapser). Most patients receiving boceprevir plus PR in both TN (86%) and TE (71%) populations were eligible for reduced treatment duration. Anemia was increased in patients receiving boceprevir plus PR vs PR alone (47.2% vs 24.4%); there was a corresponding increase in ribavirin dose reduction and erythropoietin use. Among patients receiving boceprevir plus PR, SVR rates were similar in patients with anemia (< 10 g/dL) and those without anemia (71.2% vs 77.4%). Regulatory approval has been obtained for boceprevir plus PR in Russian patients with HCV genotype 1 infection based on the results of this study.

Boceprevir plus peginterferon/ribavirin for treatment of chronic hepatitis C in Russia

PubMed Central

Isakov, Vasily; Nikitin, Igor; Chulanov, Vladimir; Ogurtsov, Pavel; Lukyanova, Ekaterina; Long, Jianmin; Wahl, Janice; Helmond, Frans A

2016-01-01

AIM: To evaluate addition of boceprevir to peginterferon/ribavirin (PR) in Russian patients with chronic hepatitis C virus (HCV). METHODS: Treatment-naive (TN) and treatment-experienced (TE) patients (who had failed prior treatment with PR for ≥ 12 wk) with chronic HCV genotype 1 infection were enrolled in this placebo-controlled, double-blind study. All patients initially received PR for 4 wk. Patients randomized to control treatment then received PR for an additional 44 wk. TN patients randomized to triple therapy received boceprevir (800 mg three times daily) plus PR for 24 wk and then further therapy according to treatment week 8 (TW8) HCV RNA levels. TE patients received boceprevir plus PR for 32 wk and then further therapy according to TW8 HCV RNA levels. Treatment was discontinued for TN patients with detectable HCV RNA at TW24 and TE patients with detectable HCV RNA at TW12 because of futility. The primary efficacy end point was sustained virologic response (SVR) defined as undetectable HCV RNA 24 wk after completing all study therapy. RESULTS: SVR was 74.8% in the boceprevir plus PR arm compared with 46.2% in the control arm, with a stratification-adjusted treatment difference of 29.2% (95%CI: 16.4-41.5; P < 0.0001). Rates of SVR were higher in the boceprevir arm in both TN and TE patient groups (TN 78.4% vs 56.3%; TE 69.4% vs 30.0%). Within TE patients, the rates of SVR were higher with boceprevir plus PR compared with PR, regardless of treatment failure type (null responder, partial responder, and relapser). Most patients receiving boceprevir plus PR in both TN (86%) and TE (71%) populations were eligible for reduced treatment duration. Anemia was increased in patients receiving boceprevir plus PR vs PR alone (47.2% vs 24.4%); there was a corresponding increase in ribavirin dose reduction and erythropoietin use. Among patients receiving boceprevir plus PR, SVR rates were similar in patients with anemia (< 10 g/dL) and those without anemia (71.2% vs 77.4%). CONCLUSION: Regulatory approval has been obtained for boceprevir plus PR in Russian patients with HCV genotype 1 infection based on the results of this study. PMID:26962399

Willingness of community-recruited men who have sex with men in Washington, DC to use long-acting injectable HIV pre-exposure prophylaxis

PubMed Central

Patrick, Rudy; Gamble, Jonjelyn; Rawls, Anthony; Opoku, Jenevieve; Magnus, Manya; Kharfen, Michael; Greenberg, Alan E.; Kuo, Irene

2017-01-01

Objectives Clinical trials are currently investigating the safety and efficacy of long-acting injectable (LAI) agents as HIV pre-exposure prophylaxis (PrEP). Using National HIV Behavioral Surveillance data, we assessed the self-reported willingness of men who have sex with men (MSM) to use LAI PrEP and their preference for LAI versus daily oral PrEP. Methods In 2014, venue-based sampling was used to recruit MSM aged ≥18 years in Washington, DC. Participants completed an interviewer-administered survey followed by voluntary HIV testing. This analysis included MSM who self-reported negative/unknown HIV status at study entry. Correlates of being “very likely” to use LAI PrEP and preferring it to daily oral PrEP were identified using multivariable logistic regression. Results Of 314 participants who self-reported negative/unknown HIV status, 50% were <30 years old, 41% were non-Hispanic Black, 37% were non-Hispanic White, and 14% were Hispanic. If LAI PrEP were offered for free or covered by health insurance, 62% were very likely, 25% were somewhat likely, and 12% were unlikely to use it. Regarding preferred PrEP modality, 67% chose LAI PrEP, 24% chose oral PrEP, and 9% chose neither. Correlates of being very likely versus somewhat likely/unlikely to use LAI PrEP included age <30 years (aOR 1.64; 95% CI 1.00–2.68), reporting ≥6 (vs. 1) sex partners in the last year (aOR 2.60; 95% CI 1.22–5.53), previous oral PrEP use (aOR 3.67; 95% CI 1.20–11.24), and being newly identified as HIV-infected during study testing (aOR 4.83; 95% CI 1.03–22.67). Black (vs. White) men (aOR 0.48; 95% CI 0.24–0.96) and men with an income of <$20,000 (vs. ≥$75,000; aOR 0.37; 95% CI 0.15–0.93) were less likely to prefer LAI to oral PrEP. Conclusions If LAI PrEP were found to be efficacious, its addition to the HIV prevention toolkit could facilitate more complete PrEP coverage among MSM at risk for HIV. PMID:28827821

VIEW OF PARTIALLY EXCAVATED MILL RUINS LOOKING NORTHWEST SHOWING UNIDENTIFIED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF PARTIALLY EXCAVATED MILL RUINS LOOKING NORTHWEST SHOWING UNIDENTIFIED PIT IN RIGHT FOREGROUND, MASONRY BASE FOR STEAM ENGINE AND CANE MILL IN LEFT CENTER, PURGING HOUSE AND CHIMNEY IN BACKGROUND - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

Antiprion activity of DB772 and related monothiophene-and furan-based analogs in a persistently infected ovine microglia culture system

USDA-ARS?s Scientific Manuscript database

The transmissible spongiform encephalopathies are fatal neurodegenerative disorders characterized by the misfolding of the native cellular prion protein (PrP-C) into the accumulating, disease-associated isoform (PrP-Sc). Despite extensive research into the inhibition of prion accumulation, no effect...

Problem-based writing with peer review improves academic performance in physiology.

PubMed

Pelaez, Nancy J

2002-12-01

The aim of this study was to determine whether problem-based writing with peer review (PW-PR) improves undergraduate student performance on physiology exams. Didactic lectures were replaced with assignments to give students practice explaining their reasoning while solving qualitative problems, thus transferring the responsibility for abstraction and generalization to the students. Performance on exam items about concepts taught using PW-PR was compared with performance on concepts taught using didactic lectures followed by group work. Calibrated Peer Review, a Web-delivered program, was used to collect student essays and to manage anonymous peer review after students "passed" three calibration peer reviews. Results show that the students had difficulty relating concepts. Relationship errors were categorized as (1) problems recognizing levels of organization, (2) problems with cause/effect, and (3) overgeneralizations. For example, some described cells as molecules; others thought that vesicles transport materials through the extracellular fluid. With PW-PR, class discussion was used to confront and resolve such difficulties. Both multiple-choice and essay exam results were better with PW-PR instead of lecture.

A Region Tracking-Based Vehicle Detection Algorithm in Nighttime Traffic Scenes

PubMed Central

Wang, Jianqiang; Sun, Xiaoyan; Guo, Junbin

2013-01-01

The preceding vehicles detection technique in nighttime traffic scenes is an important part of the advanced driver assistance system (ADAS). This paper proposes a region tracking-based vehicle detection algorithm via the image processing technique. First, the brightness of the taillights during nighttime is used as the typical feature, and we use the existing global detection algorithm to detect and pair the taillights. When the vehicle is detected, a time series analysis model is introduced to predict vehicle positions and the possible region (PR) of the vehicle in the next frame. Then, the vehicle is only detected in the PR. This could reduce the detection time and avoid the false pairing between the bright spots in the PR and the bright spots out of the PR. Additionally, we present a thresholds updating method to make the thresholds adaptive. Finally, experimental studies are provided to demonstrate the application and substantiate the superiority of the proposed algorithm. The results show that the proposed algorithm can simultaneously reduce both the false negative detection rate and the false positive detection rate.

Optimization of Hyaluronidase Inhibition Activity from Prunus davidiana (Carriere) Franch Fruit Extract Fermented by its Isolated Bacillus subtilis Strain SPF4211.

PubMed

Kim, Won-Baek; Park, So Hae; Koo, Kyoung Yoon; Kim, Bo Ram; Kim, Minji; Lee, Heeseob

2016-09-28

Strain SPF4211, having hyaluronidase (HAase) inhibition activity, was isolated from P. davidiana (Carriere) Franch fruit (PrDF) sugar extract. The phenotypic and biochemical properties based on 16S rDNA sequencing and an API 50 CHB kit suggested that the organism was B. subtilis. To optimize the HAase inhibition activity of PrDF extract by fermentation of strain SPF4211, a central composite design (CCD) was introduced based on three variables: concentration of PrDF extract (X₁: 1-5%), amount of starter culture (X₂: 1-5%), and fermentation time (X₃: 0-7 days). The experimental data were fitted with quadratic regression equations, and the accuracy of the equations was analyzed by ANOVA. The statistical model predicted the highest HAase inhibition activity of 37.936% under the optimal conditions of X₁ = 1%, X₂ = 2.53%, and X₃ = 7 days. The optimized conditions were validated by observation of an actual HAase inhibition activity of 38.367% from extract of PrDF fermented by SPF4211. These results agree well with the predicted model value.

Precise integration of inducible transcriptional elements (PrIITE) enables absolute control of gene expression.

PubMed

Pinto, Rita; Hansen, Lars; Hintze, John; Almeida, Raquel; Larsen, Sylvester; Coskun, Mehmet; Davidsen, Johanne; Mitchelmore, Cathy; David, Leonor; Troelsen, Jesper Thorvald; Bennett, Eric Paul

2017-07-27

Tetracycline-based inducible systems provide powerful methods for functional studies where gene expression can be controlled. However, the lack of tight control of the inducible system, leading to leakiness and adverse effects caused by undesirable tetracycline dosage requirements, has proven to be a limitation. Here, we report that the combined use of genome editing tools and last generation Tet-On systems can resolve these issues. Our principle is based on precise integration of inducible transcriptional elements (coined PrIITE) targeted to: (i) exons of an endogenous gene of interest (GOI) and (ii) a safe harbor locus. Using PrIITE cells harboring a GFP reporter or CDX2 transcription factor, we demonstrate discrete inducibility of gene expression with complete abrogation of leakiness. CDX2 PrIITE cells generated by this approach uncovered novel CDX2 downstream effector genes. Our results provide a strategy for characterization of dose-dependent effector functions of essential genes that require absence of endogenous gene expression. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Toward a Framework for Systematic Error Modeling of NASA Spaceborne Radar with NOAA/NSSL Ground Radar-Based National Mosaic QPE

NASA Technical Reports Server (NTRS)

Kirstettier, Pierre-Emmanual; Honh, Y.; Gourley, J. J.; Chen, S.; Flamig, Z.; Zhang, J.; Howard, K.; Schwaller, M.; Petersen, W.; Amitai, E.

2011-01-01

Characterization of the error associated to satellite rainfall estimates is a necessary component of deterministic and probabilistic frameworks involving space-born passive and active microwave measurement") for applications ranging from water budget studies to forecasting natural hazards related to extreme rainfall events. We focus here on the error structure of NASA's Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) quantitative precipitation estimation (QPE) at ground. The problem is addressed by comparison of PR QPEs with reference values derived from ground-based measurements using NOAA/NSSL ground radar-based National Mosaic and QPE system (NMQ/Q2). A preliminary investigation of this subject has been carried out at the PR estimation scale (instantaneous and 5 km) using a three-month data sample in the southern part of US. The primary contribution of this study is the presentation of the detailed steps required to derive trustworthy reference rainfall dataset from Q2 at the PR pixel resolution. It relics on a bias correction and a radar quality index, both of which provide a basis to filter out the less trustworthy Q2 values. Several aspects of PR errors arc revealed and quantified including sensitivity to the processing steps with the reference rainfall, comparisons of rainfall detectability and rainfall rate distributions, spatial representativeness of error, and separation of systematic biases and random errors. The methodology and framework developed herein applies more generally to rainfall rate estimates from other sensors onboard low-earth orbiting satellites such as microwave imagers and dual-wavelength radars such as with the Global Precipitation Measurement (GPM) mission.

UV-Vis-NIR luminescence properties and energy transfer mechanism of LiSrPO4:Eu2+, Pr3+ suitable for solar spectral convertor.

PubMed

Chen, Yan; Wang, Jing; Liu, Chunmeng; Tang, Jinke; Kuang, Xiaojun; Wu, Mingmei; Su, Qiang

2013-02-11

An efficient near-infrared (NIR) phosphor LiSrPO(4):Eu(2+), Pr(3+) is synthesized by solid-state reaction and systematically investigated using x-ray diffraction, diffuse reflection spectrum, photoluminescence spectra at room temperature and 3 K, and the decay curves. The UV-Vis-NIR energy transfer mechanism is proposed based on these results. The results demonstrate Eu(2+) can be an efficient sensitizer for harvesting UV photon and greatly enhancing the NIR emission of Pr(3+) between 960 and 1060 nm through efficient energy feeding by allowed 4f-5d absorption of Eu(2+) with high oscillator strength. Eu(2+)/Pr(3+) may be an efficient donor-acceptor pair as solar spectral converter for Si solar cells.

Base-stabilized silaimine and its donor-free dimer derived from the reaction of NHC-supported silylene with SiCl4.

PubMed

Cui, Haiyan; Cui, Chunming

2015-12-21

Reaction of the N-heterocyclic carbene (NHC)-stabilized silylene ArN(SiMe3)Si(IiPr)Cl (1, Ar = 2,6-iPr2C6H3, IiPr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) with SiCl4 resulted in the formation of three different products NHC-stabilized dichlorosilaimine ArN=Si(IiPr)Cl2 (2), aminotrichlorosilane ArN(SiMe3)SiCl3 (3) and a silaimine dimer (ArNSiCl2)2 (4) under different conditions. The products can be controlled by reaction conditions. Compound 2 is the first example of a less bulky NHC-supported silaimine via the reaction of a silylene with SiCl4.

HIV Prevention: Opportunities and Challenges

PubMed Central

Marrazzo, Jeanne M.

2016-01-01

Preexposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF)-based regimens has been shown to be effective in preventing acquisition of HIV infection, with protective efficacy being dependent on adherence to treatment. Data from the PROUD (Preexposure Option for Reducing HIV in the UK) and IPERGAY (Action to Pre vent Risk Exposure By and For Gay Men) studies, the latter of which employed event-driven PrEP, showed a high rate of protective efficacy of PrEP with TDF and emtricitabine among men who have sex with men. Data from the ASPIRE (A Study to Prevent Infection With a Ring for Extended Use) study of a dapivirine vaginal ring showed a moderate rate of protective efficacy among women older than 21 years. Ongoing investigations are examining long-acting PrEP modalities and combination PrEP and contraception products. This article summarizes a presentation by Jeanne M. Marrazzo, MD, MPH, at the IAS–USA continuing education program, Improving the Management of HIV Disease, held in Washington, DC, in April 2016. PMID:28208119

HIV Prevention: Opportunities and Challenges.

PubMed

Marrazzo, Jeanne M

Preexposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF)-based regimens has been shown to be effective in preventing acquisition of HIV infection, with protective efficacy being dependent on adherence to treatment. Data from the PROUD (Preexposure Option for Reducing HIV in the UK) and IPERGAY (Action to Prevent Risk Exposure By and For Gay Men) studies, the later of which employed event-driven PrEP, showed a high rate of protective efficacy of PrEP with TDF and emtricitabine among men who have sex with men. Data from the ASPIRE (A Study to Prevent Infection With a Ring for Extended Use) study of a dapivirine vaginal ring showed a moderate rate of protective efficacy among women older than 21 years. Ongoing investigations are examining long-acting PrEP modalities and combination PrEP and contraception products. This article summarizes a presentation by Jeanne M. Marrazzo, MD, MPH, at the IAS-USA continuing education program, Improving the Management of HIV Disease, held in Washington, DC, in April 2016.

Effect of polymer additives on characteristics of direct-current motor with liquid dielectric filler

NASA Astrophysics Data System (ADS)

Ivanov, V. I.; Bashkatova, S. T.; Lubsanova, A. A.; Tokarev, S. B.; Zadaroshnaya, G. N.; Pastukhova, I. N.

1984-11-01

In d.c. motors filled with dielectric of the hydrocarbon kind hydrodynamic losses can constitute up to 40% of the total losses. Consequently, a study was made to determine the proper additive and amount to reduce the hydraulic drag without dehomogenizing the liquid filler over long operating periods. Two polymethacrylates, never before used for this application were selected. Two motors of different size, a 0.8 kW DPK and a 6 kW DPK, were tested in kerosene with 0.005-1.0 wt% of these additives. An evaluation of the data, including the hydraulic drag coefficient as a function of the Reynolds number and the temperature rise at critical motor components (armature winding in slots, armature endturns on drive side, armature teeth, liquid in interpolar space, field winding, pole pieces) with or without additive, has yielded the optimum range of additive concentration for each motor size. An evaluation of the heat transfer at critical surfaces, with the aid of dimensional analysis, has yielded the semiempirical relation Nu=CRe0.65Pr0.4Km (C- constant factor different for each surface, Km- constant factor with exponent different for each additive polymer materials). The results can be extended to transformer oil and diesel oil as liquid motor-filling medium.

Fragment-based screen against HIV protease.

PubMed

Perryman, Alexander L; Zhang, Qing; Soutter, Holly H; Rosenfeld, Robin; McRee, Duncan E; Olson, Arthur J; Elder, John E; Stout, C David

2010-03-01

We have employed a fragment-based screen against wild-type (NL4-3) HIV protease (PR) using the Active Sight fragment library and X-ray crystallography. The experiments reveal two new binding sites for small molecules. PR was co-crystallized with fragments, or crystals were soaked in fragment solutions, using five crystal forms, and 378 data sets were collected to 2.3-1.3 A resolution. Fragment binding induces a distinct conformation and specific crystal form of TL-3 inhibited PR during co-crystallization. One fragment, 2-methylcyclohexanol, binds in the 'exo site' adjacent to the Gly(16)Gly(17)Gln(18)loop where the amide of Gly(17)is a specific hydrogen bond donor, and hydrophobic contacts occur with the side chains of Lys(14)and Leu(63). Another fragment, indole-6-carboxylic acid, binds on the 'outside/top of the flap' via hydrophobic contacts with Trp(42), Pro(44), Met(46), and Lys(55), a hydrogen bond with Val(56), and a salt-bridge with Arg(57). 2-acetyl-benzothiophene also binds at this site. This study is the first fragment-based crystallographic screen against HIV PR, and the first time that fragments were screened against an inhibitor-bound drug target to search for compounds that both bind to novel sites and stabilize the inhibited conformation of the target.

Fragment-Based Screen against HIV Protease

PubMed Central

Perryman, A. L.; Zhang, Q.; Soutter, H. H.; Rosenfeld, R.; McRee, D. E.; Olson, A. J.; Elder, J. E.; Stout, C. D.

2009-01-01

We have employed a fragment-based screen against wild-type (NL4-3) HIV protease (PR) using the Active Sight fragment library and X-ray crystallography. The experiments reveal two new binding sites for small molecules. PR was co-crystallized with fragments, or crystals were soaked in fragment solutions, using five crystal forms, and 378 data sets were collected to 2.3-1.3 Å resolution. Fragment binding induces a distinct conformation and specific crystal form of TL-3 inhibited PR during co-crystallization. One fragment, 2-methylcyclohexanol, binds in the ‘exo site’ adjacent to the Gly16Gly17Gln18 loop where the amide of Gly17 is a specific hydrogen bond donor, and hydrophobic contacts occur with the side chains of Lys14 and Leu63. Another fragment, indole-6-carboxylic acid, binds on the ‘outside/top of the flap’ via hydrophobic contacts with Trp42, Pro44, Met46, and Lys55, a hydrogen bond with Val56, and a salt-bridge with Arg57. 2-acetyl-benzothiophene also binds at this site. This study is the first fragment-based crystallographic screen against HIV PR, and the first time that fragments were screened against an inhibitor-bound drug target to search for compounds that both bind to novel sites and stabilize the inhibited conformation of the target. PMID:20659109

Effects of proprioceptive exercises on pain and function in chronic neck- and low back pain rehabilitation: a systematic literature review.

PubMed

McCaskey, Michael A; Schuster-Amft, Corina; Wirth, Brigitte; Suica, Zorica; de Bruin, Eling D

2014-11-19

Proprioceptive training (PrT) is popularly applied as preventive or rehabilitative exercise method in various sports and rehabilitation settings. Its effect on pain and function is only poorly evaluated. The aim of this systematic review was to summarise and analyse the existing data on the effects of PrT on pain alleviation and functional restoration in patients with chronic (≥ 3 months) neck- or back pain. Relevant electronic databases were searched from their respective inception to February 2014. Randomised controlled trials comparing PrT with conventional therapies or inactive controls in patients with neck- or low back pain were included. Two review authors independently screened articles and assessed risk of bias (RoB). Data extraction was performed by the first author and crosschecked by a second author. Quality of findings was assessed and rated according to GRADE guidelines. Pain and functional status outcomes were extracted and synthesised qualitatively and quantitatively. In total, 18 studies involving 1380 subjects described interventions related to PrT (years 1994-2013). 6 studies focussed on neck-, 12 on low back pain. Three main directions of PrT were identified: Discriminatory perceptive exercises with somatosensory stimuli to the back (pPrT, n=2), multimodal exercises on labile surfaces (mPrT, n=13), or joint repositioning exercise with head-eye coordination (rPrT, n=3). Comparators entailed usual care, home based training, educational therapy, strengthening, stretching and endurance training, or inactive controls. Quality of studies was low and RoB was deemed moderate to high with a high prevalence of unclear sequence generation and group allocation (>60%). Low quality evidence suggests PrT may be more effective than not intervening at all. Low quality evidence suggests that PrT is no more effective than conventional physiotherapy. Low quality evidence suggests PrT is inferior to educational and behavioural approaches. There are few relevant good quality studies on proprioceptive exercises. A descriptive summary of the evidence suggests that there is no consistent benefit in adding PrT to neck- and low back pain rehabilitation and functional restoration.

A dynamical systems model of progesterone receptor interactions with inflammation in human parturition.

PubMed

Brubaker, Douglas; Barbaro, Alethea; R Chance, Mark; Mesiano, Sam

2016-08-19

Progesterone promotes uterine relaxation and is essential for the maintenance of pregnancy. Withdrawal of progesterone activity and increased inflammation within the uterine tissues are key triggers for parturition. Progesterone actions in myometrial cells are mediated by two progesterone receptor (PR) isoforms, PR-A and PR-B, that function as ligand-activated transcription factors. PR-B mediates relaxatory actions of progesterone, in part, by decreasing myometrial cell responsiveness to pro-inflammatory stimuli. These same pro-inflammatory stimuli promote the expression of PR-A which inhibits the anti-inflammatory activity of PR-B. Competitive interaction between the progesterone receptors then augments myometrial responsiveness to pro-inflammatory stimuli. The interaction between PR-B transcriptional activity and inflammation in the pregnancy myometrium is examined using a dynamical systems model in which quiescence and labor are represented as phase-space equilibrium points. Our model shows that PR-B transcriptional activity and the inflammatory load determine the stability of the quiescent and laboring phenotypes. The model is tested using published transcriptome datasets describing the mRNA abundances in the myometrium before and after the onset of labor at term. Surrogate transcripts were selected to reflect PR-B transcriptional activity and inflammation status. The model coupling PR-B activity and inflammation predicts contractile status (i.e., laboring or quiescent) with high precision and recall and outperforms uncoupled single and two-gene classifiers. Linear stability analysis shows that phase space bifurcations exist in our model that may reflect the phenotypic states of the pregnancy uterus. The model describes a possible tipping point for the transition of the quiescent to the contractile laboring phenotype. Our model describes the functional interaction between the PR-A:PR-B hypothesis and tissue level inflammation in the pregnancy uterus and is a first step in more sophisticated dynamical systems modeling of human partition. The model explains observed biochemical dynamics and as such will be useful for the development of a range of systems-based models using emerging data to predict preterm birth and identify strategies for its prevention.

ESO PR Highlights in 2006

NASA Astrophysics Data System (ADS)

2007-01-01

Last year proved to be another exceptional year for the European organisation for ground-based astronomy. ESO should begin the New Year with two new member states: Spain (PR 05/06) and the Czech Republic (PR 52/06). ESO PR Highlights 2006 2006 was a year of renovation and revolution in the world of planets. A new Earth-like exoplanet has been discovered (PR 03/06) using a network of telescopes from all over the world (including the Danish 1.54-m one at ESO La Silla). It is not the only child of this fruitful year: thanks to the combined use of ESO's Very Large Telescope (VLT) and La Silla instruments, a surprising system of twin giant exoplanets was found (PR 29/06), and a trio of Neptune-like planets hosted by a nearby star were identified (PR 18/06). These results open new perspectives on the search for habitable zones and on the understanding of the mechanism of planet formation. The VISIR instrument on the VLT has been providing unique information to answer this last question, by supplying a high resolution view of a planet-forming disc (PR 36/06). There are not only new members in the planets' register: during the General Assembly of the International Astronomical Union held in Prague (Czech Republic), it was decided that Pluto is not a planet anymore but a 'dwarf planet'. Whatever its status, Pluto still has a satellite, Charon, whose radius and density have been measured more accurately by observing a rare occultation from different sites, including Cerro Paranal (PR 02/06). The scientific community dedicated 2006 to the great physicist James Clerk Maxwell (it was the 175th anniversary of the birth): without his electromagnetic theory of light, none of the astonishing discoveries of modern physics could have been achieved. Nowadays we can look at distant galaxies in great detail: the GIRAFFE spectrograph on the VLT revealed that galaxies 6 billion years ago had the same amount of dark matter relative to stars than nowadays (PR 10/06), while SINFONI gave an unprecedented detailed map of a proto-disc galaxy, showing how galaxies looked like 10 billion years ago (PR 31/06). The VLT also helped to discover a large primordial (more than 10 billion years away) 'blob', explained as the early stage formation of a galaxy (PR 23/06). Not only far away galaxies are rich of surprises: also our own Galaxy was the object of investigations during 2006 and its history is now less obscure (PR 34/06 and 41/06). ESO's Very Large Telescope unveiled that the stellar cluster Messier 12 must have lost to our Milky Way galaxy close to one million low-mass stars (PR 04/06). Stealing is not uncommon in astronomy: evidence of stellar vampires - star sucking off material from another - was unearthed in the globular cluster 47 Tucanae (PR 37/06). Still closer to home, the VLT observed Schwassmann-Wachmann 3, a comet that is breaking apart and revealed many mini-comets (PR 15/06). At Paranal, a fourth Auxiliary Telescope was installed for the Very Large Telescope Interferometer (PR 51/06), and since January 2006, not only do natural stars shine: the first artificial star twinkles in the Southern Hemisphere. It does not guide the sailors (it is too faint to be seen by the unaided eye), but it conducts the eye of the present and future telescopes (PR 07/06). And 2006 proved an important year for the future project of ESO, the Extremely Large Telescope. After approval from the ESO council, the European community can now start the final design of this telescope that will without doubt revolutionise astronomy (PR 25/06 and 46/06). ESO PR Photos 2006 2006 was without doubt an explosive year: the explosion of a supernovae of Type Ia in the enchanting Hooked Galaxy was followed from the middle of 2005 for more than a year (PR 22/06) and using observations of 17 supernovae Ia astronomers could make light on the nature of such explosions, that are likely to occur at supersonic speed (PR 44/06). Supernovae are proved to be linked to X-ray flashes (PR 33/06) and to the more energetic gamma-ray bursts. But not all the explosions are associated with supernovae, and a new kind of explosion is indeed suggested by the observation of a new mysterious category of gamma-ray bursts (PR 49/06). The Atacama Pathfinder Experiment (APEX) 12-m sub-millimetre telescope lived up to the ambitions of the scientists by providing access to the 'Cold Universe' with unprecedented sensitivity and image quality. As a demonstration, no less than 26 articles based on early science with APEX were published in a special issue of the research journal Astronomy & Astrophysics (PR 24/06). This year ESO and Chile celebrated ten years of collaboration: a cooperation that led not only to breakthrough discoveries, but also to a growth of astronomy and related sciences in the South American country (PR 21/06). ESO published many images last year as well, including two huge ones, made with the Wide Field Imager: one, made of about 300 million pixels, shows an 'empty field' (PR 14/06), while the other, a 256 million pixel mosaic, depicts in amazing detail the Tarantula Nebula (PR 50/06). These and other images can be accessed through the clickable map, including amazing images of galaxies and of a finally identified flying object (PR 48/06).

[Social support and physical activity in adolescents from public schools: the importance of family and friends].

PubMed

Prado, Crisley Vanessa; Lima, Alex Vieira; Fermino, Rogério César; Añez, Ciro Romelio Rodriguez; Reis, Rodrigo Siqueira

2014-04-01

The aim of this study was to verify the association between different types and sources of social support and physical activity among adolescents from Curitiba, Paraná State, Brazil. A school-based survey was conducted with a representative sample of adolescents from public schools (n = 1,469). Multiple regression models were used to test the association between weekly frequency and sources of social support from family and friends and weekly frequency of physical activity. Among boys, frequent company of family (PR: 2.88; 95%CI: 2.00-4.13) and friends (PR: 5.46; 95%CI: 2.33-12.78) and positive reinforcement from friends (PR: 1.81; 95%CI: 1.18-2.77) were positively associated with physical activity. Sporadic invitation by the family was negatively associated with physical activity (PR: 0.66; 95%CI: 0.46-1.14). For girls, frequent company of family (PR: 3.39; 95%CI: 1.49-7.69) and friends (PR: 4.06; 95%CI: 2.22-7.45) increased the likelihood of physical activity. Company of friends was the most important type of social support for physical activity among these adolescents.

Alzheimer's Disease and Prion Protein

PubMed Central

Zhou, Jiayi; Liu, Bingqian

2013-01-01

Summary Alzheimer's disease (AD) is a devastating neurodegenerative disease with progressive loss of memory and cognitive function, pathologically hallmarked by aggregates of the amyloid-beta (Aβ) peptide and hyperphosphorylated tau in the brain. Aggregation of Aβ under the form of amyloid fibrils has long been considered central to the pathogenesis of AD. However, recent evidence has indicated that soluble Aβ oligomers, rather than insoluble fibrils, are the main neurotoxic species in AD. The cellular prion protein (PrPC) has newly been identified as a cell surface receptor for Aβ oligomers. PrPC is a cell surface glycoprotein that plays a key role in the propagation of prions, proteinaceous infectious agents that replicate by imposing their abnormal conformation to PrPC molecules. In AD, PrPC acts to transduce the neurotoxic signals arising from Aβ oligomers, leading to synaptic failure and cognitive impairment. Interestingly, accumulating evidence has also shown that aggregated Aβ or tau possesses prion-like activity, a property that would allow them to spread throughout the brain. In this article, we review recent findings regarding the function of PrPC and its role in AD, and discuss potential therapeutic implications of PrPC-based approaches in the treatment of AD. PMID:25343100

Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar

NASA Astrophysics Data System (ADS)

Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

2010-05-01

Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and comparison of TRMM PR statistics with ground-based radar has been extended to other regions of the globe. The Australian Bureau of Meteorology C-band polarimetric radar C-Pol has been collecting data in Darwin, Australia for over a decade. The Darwin region affords the opportunity to look at precipitation characteristics over land and ocean, as well as variability associated with monsoon and break periods over long periods of time. The polarimetric X-band radar XPort was stationed in West Africa at a field site in Benin during the 2006 and 2007 African monsoon periods, where differences in rainfall associated with African Easterly Wave (AEW) passages and non-AEW periods can be examined. Similar comparisons between TRMM PR and ground based polarimetric radars will also be reported for these regions.

Molecular Dynamics Simulation Study on the Binding and Stabilization Mechanism of Antiprion Compounds to the "Hot Spot" Region of PrPC.

PubMed

Zhou, Shuangyan; Liu, Xuewei; An, Xiaoli; Yao, Xiaojun; Liu, Huanxiang

2017-11-15

Structural transitions in the prion protein from the cellular form, PrP C , into the pathological isoform, PrP Sc , are regarded as the main cause of the transmissible spongiform encephalopathies, also known as prion diseases. Hence, discovering and designing effective antiprion drugs that can inhibit PrP C to PrP Sc conversion is regarded as a promising way to cure prion disease. Among several strategies to inhibit PrP C to PrP Sc conversion, stabilizing the native PrP C via specific binding is believed to be one of the valuable approaches and many antiprion compounds have been reported based on this strategy. However, the detailed mechanism to stabilize the native PrP C is still unknown. As such, to unravel the stabilizing mechanism of these compounds to PrP C is valuable for the further design and discovery of antiprion compounds. In this study, by molecular dynamics simulation method, we investigated the stabilizing mechanism of several antiprion compounds on PrP C that were previously reported to have specific binding to the "hot spot" region of PrP C . Our simulation results reveal that the stabilization mechanism of specific binding compounds can be summarized as (I) to stabilize both the flexible C-terminal of α2 and the hydrophobic core, such as BMD42-29 and GN8; (II) to stabilize the hydrophobic core, such as J1 and GJP49; (III) to stabilize the overall structure of PrP C by high binding affinity, as NPR-056. In addition, as indicated by the H-bond analysis and decomposition analysis of binding free energy, the residues N159 and Q160 play an important role in the specific binding of the studied compounds and all these compounds interact with PrP C in a similar way with the key interacting residues L130 in the β1 strand, P158, N159, Q160, etc. in the α1-β2 loop, and H187, T190, T191, etc. in the α2 C-terminus although the compounds have large structural difference. As a whole, our obtained results can provide some insights into the specific binding mechanism of main antiprion compounds to the "hot spot" region of PrP C at the molecular level and also provide guidance for effective antiprion drug design in the future.

Light transmittance and micro-mechanical properties of bulk fill vs. conventional resin based composites.

PubMed

Bucuta, Stefan; Ilie, Nicoleta

2014-11-01

The aim of this study was to quantify the blue light that passes through different incremental thicknesses of bulk fill in comparison to conventional resin-based composites (RBCs) and to relate it to the induced mechanical properties. Seven bulk fill, five nanohybrid and two flowable RBCs were analysed. Specimens (n = 5) of three incremental thicknesses (2, 4 and 6 mm) were cured from the top for 20 s, while at the bottom, a spectrometer monitored in real time the transmitted irradiance. Micro-mechanical properties (Vickers hardness, HV, and indentation modulus, E) were measured at the top and bottom after 24 h of storage in distilled water at 37 °C. Electron microscope images were taken for assessing the filler distribution and size. Bulk fill RBCs (except SonicFill) were more translucent than conventional RBCs. Low-viscosity bulk fill materials showed the lowest mechanical properties. HV depends highly on the following parameters: material (ηp (2) = 0.952), incremental thickness (0.826), filler volume (0.747), filler weight (0.746) and transmitted irradiance (0.491). The bottom-to-top HV ratio (HVbt) was higher than 80 % in all materials in 2- and 4-mm increments (except for Premise), whereas in 6-mm increments, this is valid only in four bulk fill materials (Venus Bulk Fill, SDR, x-tra fil, Tetric EvoCeram Bulk Fill). The depth of cure is dependent on the RBC's translucency. Low-viscosity bulk fill RBCs have lower mechanical properties than all other types of analysed materials. All bulk fill RBCs (except SonicFill) are more translucent for blue light than conventional RBCs. Although bulk fill RBCs are generally more translucent, the practitioner has to follow the manufacturer's recommendations on curing technique and maximum incremental thickness.

Molecular characterization of the PR-toxin gene cluster in Penicillium roqueforti and Penicillium chrysogenum: cross talk of secondary metabolite pathways.

PubMed

Hidalgo, Pedro I; Ullán, Ricardo V; Albillos, Silvia M; Montero, Olimpio; Fernández-Bodega, María Ángeles; García-Estrada, Carlos; Fernández-Aguado, Marta; Martín, Juan-Francisco

2014-01-01

The PR-toxin is a potent mycotoxin produced by Penicillium roqueforti in moulded grains and grass silages and may contaminate blue-veined cheese. The PR-toxin derives from the 15 carbon atoms sesquiterpene aristolochene formed by the aristolochene synthase (encoded by ari1). We have cloned and sequenced a four gene cluster that includes the ari1 gene from P. roqueforti. Gene silencing of each of the four genes (named prx1 to prx4) resulted in a reduction of 65-75% in the production of PR-toxin indicating that the four genes encode enzymes involved in PR-toxin biosynthesis. Interestingly the four silenced mutants overproduce large amounts of mycophenolic acid, an antitumor compound formed by an unrelated pathway suggesting a cross-talk of PR-toxin and mycophenolic acid production. An eleven gene cluster that includes the above mentioned four prx genes and a 14-TMS drug/H(+) antiporter was found in the genome of Penicillium chrysogenum. This eleven gene cluster has been reported to be very poorly expressed in a transcriptomic study of P. chrysogenum genes under conditions of penicillin production (strongly aerated cultures). We found that this apparently silent gene cluster is able to produce PR-toxin in P. chrysogenum under static culture conditions on hydrated rice medium. Noteworthily, the production of PR-toxin was 2.6-fold higher in P. chrysogenum npe10, a strain deleted in the 56.8kb amplifiable region containing the pen gene cluster, than in the parental strain Wisconsin 54-1255 providing another example of cross-talk between secondary metabolite pathways in this fungus. A detailed PR-toxin biosynthesis pathway is proposed based on all available evidence. Copyright © 2013 Elsevier Inc. All rights reserved.

Interspecific Sex in Grass Smuts and the Genetic Diversity of Their Pheromone-Receptor System

PubMed Central

Kellner, Ronny; Vollmeister, Evelyn; Feldbrügge, Michael; Begerow, Dominik

2011-01-01

The grass smuts comprise a speciose group of biotrophic plant parasites, so-called Ustilaginaceae, which are specifically adapted to hosts of sweet grasses, the Poaceae family. Mating takes a central role in their life cycle, as it initiates parasitism by a morphological and physiological transition from saprobic yeast cells to pathogenic filaments. As in other fungi, sexual identity is determined by specific genomic regions encoding allelic variants of a pheromone-receptor (PR) system and heterodimerising transcription factors. Both operate in a biphasic mating process that starts with PR–triggered recognition, directed growth of conjugation hyphae, and plasmogamy of compatible mating partners. So far, studies on the PR system of grass smuts revealed diverse interspecific compatibility and mating type determination. However, many questions concerning the specificity and evolutionary origin of the PR system remain unanswered. Combining comparative genetics and biological approaches, we report on the specificity of the PR system and its genetic diversity in 10 species spanning about 100 million years of mating type evolution. We show that three highly syntenic PR alleles are prevalent among members of the Ustilaginaceae, favouring a triallelic determination as the plesiomorphic characteristic of this group. Furthermore, the analysis of PR loci revealed increased genetic diversity of single PR locus genes compared to genes of flanking regions. Performing interspecies sex tests, we detected a high potential for hybridisation that is directly linked to pheromone signalling as known from intraspecies sex. Although the PR system seems to be optimised for intraspecific compatibility, the observed functional plasticity of the PR system increases the potential for interspecific sex, which might allow the hybrid-based genesis of newly combined host specificities. PMID:22242007

Community member perspectives from transgender women and men who have sex with men on pre-exposure prophylaxis as an HIV prevention strategy: implications for implementation

PubMed Central

2012-01-01

Background An international randomized clinical trial (RCT) on pre-exposure prophylaxis (PrEP) as an human immunodeficiency virus (HIV)-prevention intervention found that taken on a daily basis, PrEP was safe and effective among men who have sex with men (MSM) and male-to-female transgender women. Within the context of the HIV epidemic in the United States (US), MSM and transgender women are the most appropriate groups to target for PrEP implementation at the population level; however, their perspectives on evidenced-based biomedical research and the results of this large trial remain virtually unknown. In this study, we examined the acceptability of individual daily use of PrEP and assessed potential barriers to community uptake. Methods We conducted semi-structured interviews with an ethnoracially diverse sample of thirty HIV-negative and unknown status MSM (n = 24) and transgender women (n = 6) in three California metropolitan areas. Given the burden of disease among ethnoracial minorities in the US, we purposefully oversampled for these groups. Thematic coding and analysis of data was conducted utilizing an approach rooted in grounded theory. Results While participants expressed general interest in PrEP availability, results demonstrate: a lack of community awareness and confusion about PrEP; reservations about PrEP utilization, even when informed of efficacious RCT results; and concerns regarding equity and the manner in which a PrEP intervention could be packaged and marketed in their communities. Conclusions In order to effectively reduce HIV health disparities at the population level, PrEP implementation must take into account the uptake concerns of those groups who would actually access and use this biomedical intervention as a prevention strategy. Recommendations addressing these concerns are provided. PMID:23181780

New insights into flavivirus biology: the influence of pH over interactions between prM and E proteins

NASA Astrophysics Data System (ADS)

Oliveira, Edson R. A.; de Alencastro, Ricardo B.; Horta, Bruno A. C.

2017-11-01

Diseases caused by flaviviruses, such as dengue and zika, are globally recognized as major threats. During infection, a critical point in their replicative cycle is the maturation step, which occurs throughout the cellular exocytic pathway. This step is a pH-dependent process that involves the modification of the viral envelope by converting prM (pre-membrane) into M (membrane) proteins with the release of a "pr peptide". After this reaction, the pr peptides remain bound to the viral envelope while the virions cross the acidic trans-Golgi network, and are released only at neutral pH after secretion of the virus particles. Despite this current knowledge, the molecular basis of the flavivirus maturation step is largely unknown. Here, based on the crystal structure of the dengue pr-E complex ("pr peptide" bound to virus envelope protein) and using molecular dynamics simulations, we found that the pH shift from acidic to neutral yields considerable structural changes in the system. Dynamic cross correlation maps and root mean square deviation analyses revealed that the pr-E junction is clearly unstable under neutral pH. Secondary structure analysis also revealed that the fusion loop region, present in the E protein, is sensitive to pH and tends to unstructure at a neutral environment. Moreover, we found that five residues present in the E protein, Gly102, His244, Thr70, Thr68 and Asn67 are critical to confer stability to the pr-E complex while inside the Golgi apparatus. This work brings details about the dynamical behavior of the pr-E system, helps to better understand the flavivirus biology and may also be of use in the development of novel antiviral strategies.

Signal transducer and activator of transcription-3 (Stat3) plays a critical role in implantation via progesterone receptor in uterus

PubMed Central

Lee, Jae Hee; Kim, Tae Hoon; Oh, Seo Jin; Yoo, Jung-Yoon; Akira, Shizuo; Ku, Bon Jeong; Lydon, John P.; Jeong, Jae-Wook

2013-01-01

Recent studies have shown that activation of the signal transducer and activator of transcription-3 (Stat3) is required for decidualization, interacting with progesterone receptor (PR) in uterus. Based on previous reports, we hypothesized that crosstalk between STAT3 and PR signaling is required for successful implantation. To identify the interaction between STAT3 and PR isoforms, we performed immunoprecipitation following transient cotransfection and found that STAT3 physically interacted with PR-A, which is known to be important for uterine development and function, but not with PR-B. To further investigate the role of Stat3 in uterine function, Stat3 was conditionally ablated only in the PR-positive cells (PRcre/+ Stat3f/f; Stat3d/d). Our studies revealed that ovarian function and uterine development of Stat3d/d mice were normal. However, Stat3d/d female mice were infertile due to defective embryo implantation. Unlike Stat3f/f mice, Stat3d/d mice exhibited an unclosed uterine lumen. Furthermore, uteri of Stat3d/d mice were unable to undergo a well-characterized hormonally induced decidual reaction. The expression of stromal PR was decreased during decidualization and preimplantation period in Stat3d/d mice, and PR target genes were significantly down-regulated after progesterone induction. Our results suggest that STAT3 and PR crosstalk is required for successful implantation in the mouse uterus.—Lee, J. H., Kim, T. H., Oh, S. J., Yoo, J.-Y., Akira, S., Ku, B. J., Lydon, J. P., Jeong, J.-W. Signal transducer and activator of transcription-3 (Stat3) plays a critical role in implantation via progesterone receptor in uterus. PMID:23531596

Risk Analysis of Prostate Cancer in PRACTICAL, a Multinational Consortium, Using 25 Known Prostate Cancer Susceptibility Loci

PubMed Central

Amin Al Olama, Ali; Benlloch, Sara; Antoniou, Antonis C.; Zeigler-Johnson, Charnita; Stephenson, Robert; Cox, Angela; Southey, Melissa C.; Spurdle, Amanda B.; FitzGerald, Liesel; Leongamornlert, Daniel; Saunders, Edward; Tymrakiewicz, Malgorzata; Guy, Michelle; Dadaev, Tokhir; Little, Sarah J.; Govindasami, Koveela; Sawyer, Emma; Wilkinson, Rosemary; Herkommer, Kathleen; Hopper, John L.; Lophatonanon, Aritaya; Rinckleb, Antje E.; Kote-Jarai, Zsofia; Eeles, Rosalind A.; Easton, Douglas F.

2015-01-01

Background Genome-wide association studies have identified multiple genetic variants associated with prostate cancer (PrCa) risk which explain a substantial proportion of familial relative risk. These variants can be used to stratify individuals by their risk of PrCa. Methods We genotyped 25 PrCa susceptibility loci in 40,414 individuals and derived a polygenic risk score (PRS). We estimated empirical Odds Ratios for PrCa associated with different risk strata defined by PRS and derived age-specific absolute risks of developing PrCa by PRS stratum and family history. Results The PrCa risk for men in the top 1% of the PRS distribution was 30.6 (95% CI 16.4-57.3) fold compared with men in the bottom 1%, and 4.2 (95% CI 3.2-5.5) fold compared with the median risk. The absolute risk of PrCa by age 85 was 65.8% for a man with family history in the top 1% of the PRS distribution, compared with 3.7% for a man in the bottom 1%. The PRS was only weakly correlated with serum PSA level (correlation=0.09). Conclusions Risk profiling can identify men at substantially increased or reduced risk of PrCa. The effect size, measured by OR per unit PRS, was higher in men at younger ages and in men with family history of PrCa. Incorporating additional newly identified loci into a PRS should improve the predictive value of risk profiles. Impact We demonstrate that the risk profiling based on SNPs can identify men at substantially increased or reduced risk that could have useful implications for targeted prevention and screening programs. PMID:25837820

Controlled low strength materials (CLSM), reported by ACI Committee 229

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajendran, N.

1997-07-01

Controlled low-strength material (CLSM) is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted fill. Many terms are currently used to describe this material including flowable fill, unshrinkable fill, controlled density fill, flowable mortar, flowable fly ash, fly ash slurry, plastic soil-cement, soil-cement slurry, K-Krete and other various names. This report contains information on applications, material properties, mix proportioning, construction and quality-control procedures. This report`s intent is to provide basic information on CLSM technology, with emphasis on CLSM material characteristics and advantages over conventional compacted fill. Applications include backfills, structural fills, insulating and isolation fills, pavementmore » bases, conduit bedding, erosion control, void filling, and radioactive waste management.« less

Safety of oral tenofovir disoproxil fumarate-based pre-exposure prophylaxis for HIV prevention.

PubMed

Mugwanya, Kenneth K; Baeten, Jared M

2016-01-01

Tenofovir disoproxil fumarate (TDF)-based pre-exposure prophylaxis is a novel HIV prevention strategy for individuals at increased sexual risk for HIV infection. For any biomedical prevention intervention, the bar for tolerating adverse effects in healthy persons is high compared to therapeutic interventions. We provide a concise summary of the clinical safety of TDF-based pre-exposure prophylaxis with focus on TDF-related effects on tolerability, kidney function, bone density, HIV resistance, sexual and reproductive health. The evidence base for this review is derived from a literature search of both randomized and observational studies evaluating efficacy and safety of TDF-based PrEP, TDF alone or in combination with emtricitabine, identified from PUBMED and EMBASE electronic databases, clinicaltrials.gov and major HIV conferences. TDF-based pre-exposure prophylaxis is a potent intervention against HIV acquisition when taken which is generally safe and well tolerated. The risk of the small, non-progressive, and reversible decline in glomerular filtration rate and bone mineral density as well as the potential selection for drug resistance associated with PrEP are outweighed, at the population level and broadly for individuals, by PrEP's substantial reduction in the risk of HIV infection.

Association between the Frequency of Protein-Rich Food Intakes and Kihon-Checklist Frailty Indices in Older Japanese Adults: The Kyoto-Kameoka Study.

PubMed

Yamaguchi, Miwa; Yamada, Yosuke; Nanri, Hinako; Nozawa, Yoshizu; Itoi, Aya; Yoshimura, Eiichi; Watanabe, Yuya; Yoshida, Tsukasa; Yokoyama, Keiichi; Goto, Chiho; Ishikawa-Takata, Kazuko; Kobayashi, Hisamine; Kimura, Misaka

2018-01-13

We aimed to investigate whether frequencies of protein-rich food intake were associated with frailty among older Japanese adults. A cross-sectional study was conducted in 2011 among 3843 men and 4331 women in a population-based cohort of Kameoka city, Kyoto Prefecture, Japan. Frailty was assessed by the weighted score based on the 25-item Kihon-Checklist. The frequency of protein-rich food intake was examined as "seafood", "meat", "dairy products", "eggs", and "soy products". The outcome of frailty was analyzed with a multiple logistic regression model using the frequency of protein-rich food intake. When compared to the first quartile, it was observed that there was a significant association between the lower adjusted prevalence ratio (PR) for frailty and the frequency of seafood intake in the fourth quartile among men (PR 0.64, 95% confidence interval (CI), 0.42, 0.99) and from the second quartile to the third quartile among women (PR 0.61, 95% CI, 0.43, 0.85; PR 0.64, 95% CI, 0.46, 0.91). The frequency of dairy products intake in the third quartile among women was significantly associated with a lower PR for frailty ( p -value = 0.013). Our findings suggest that the consumption of seafood and dairy products may help older adults in maintaining their independence.

Association between the Frequency of Protein-Rich Food Intakes and Kihon-Checklist Frailty Indices in Older Japanese Adults: The Kyoto-Kameoka Study

PubMed Central

Yamaguchi, Miwa; Nozawa, Yoshizu; Itoi, Aya; Yoshimura, Eiichi; Watanabe, Yuya; Yoshida, Tsukasa; Yokoyama, Keiichi; Goto, Chiho; Ishikawa-Takata, Kazuko; Kobayashi, Hisamine; Kimura, Misaka

2018-01-01

We aimed to investigate whether frequencies of protein-rich food intake were associated with frailty among older Japanese adults. A cross-sectional study was conducted in 2011 among 3843 men and 4331 women in a population-based cohort of Kameoka city, Kyoto Prefecture, Japan. Frailty was assessed by the weighted score based on the 25-item Kihon-Checklist. The frequency of protein-rich food intake was examined as “seafood”, “meat”, “dairy products”, “eggs”, and “soy products”. The outcome of frailty was analyzed with a multiple logistic regression model using the frequency of protein-rich food intake. When compared to the first quartile, it was observed that there was a significant association between the lower adjusted prevalence ratio (PR) for frailty and the frequency of seafood intake in the fourth quartile among men (PR 0.64, 95% confidence interval (CI), 0.42, 0.99) and from the second quartile to the third quartile among women (PR 0.61, 95% CI, 0.43, 0.85; PR 0.64, 95% CI, 0.46, 0.91). The frequency of dairy products intake in the third quartile among women was significantly associated with a lower PR for frailty (p-value = 0.013). Our findings suggest that the consumption of seafood and dairy products may help older adults in maintaining their independence. PMID:29342873

The Puerto Rico Component of the National Tsunami Hazard and Mitigation Program Pr-Nthmp

NASA Astrophysics Data System (ADS)

Huerfano Moreno, V. A.; Hincapie-Cardenas, C. M.

2014-12-01

Tsunami hazard assessment, detection, warning, education and outreach efforts are intended to reduce losses to life and property. The Puerto Rico Seismic Network (PRSN) is participating in an effort with local and federal agencies, to developing tsunami hazard risk reduction strategies under the National Tsunami Hazards and Mitigation Program (NTHMP). This grant supports the TsunamiReady program which is the base of the tsunami preparedness and mitigation in PR. The Caribbean region has a documented history of damaging tsunamis that have affected coastal areas. The seismic water waves originating in the prominent fault systems around PR are considered to be a near-field hazard for Puerto Rico and the Virgin islands (PR/VI) because they can reach coastal areas within a few minutes after the earthquake. Sources for local, regional and tele tsunamis have been identified and modeled and tsunami evacuation maps were prepared for PR. These maps were generated in three phases: First, hypothetical tsunami scenarios on the basis of the parameters of potential underwater earthquakes were developed. Secondly, each of these scenarios was simulated. The third step was to determine the worst case scenario (MOM). The run-ups were drawn on GIS referenced maps and aerial photographs. These products are being used by emergency managers to educate the public and develop mitigation strategies. Online maps and related evacuation products are available to the public via the PR-TDST (PR Tsunami Decision Support Tool). Currently all the 44 coastal municipalities were recognized as TsunamiReady by the US NWS. The main goal of the program is to declare Puerto Rico as TsunamiReady, including two cities that are not coastal but could be affected by tsunamis. Based on these evacuation maps, tsunami signs were installed, vulnerability profiles were created, communication systems to receive and disseminate tsunami messages were installed in each TWFP, and tsunami response plans were approved. Also, the existing tsunami protocol and criteria in the PR/VI was updated. This paper describes the PR-NTHMP project, including the real time earthquake and tsunami monitoring as well as the specific protocols used to broadcast tsunami messages. The paper highlights tsunami hazards assessment, detection, warning, education and outreach in Puerto Rico.

Efficacy of ProTaper retreatment system in root canals filled with gutta-percha and two endodontic sealers.

PubMed

Só, Marcus Vinícius Reis; Saran, Caroline; Magro, Miriam Lago; Vier-Pelisser, Fabiana Vieira; Munhoz, Marcelo

2008-10-01

This study evaluated the efficacy of ProTaper Universal rotary retreatment system and hand files for filling material removal during retreatment and the influence of sealer type on the presence of filling debris in the reinstrumented canals. The canals of 60 palatal roots of first molars were obturated with gutta-percha and either a zinc oxide-eugenol-based or a resin-based sealer and reinstrumented: G1, EndoFill/hand files; G2, AH Plus/hand files; G3, EndoFill/ProTaper; G4, AH Plus/ProTaper. Roots were cleaved and examined with an optical microscope, and the amount of filling debris on canal walls was analyzed on digitized images. There was no significant difference (P > .05) among the root canal thirds within each group. G3 presented significantly more filling debris than G1 in the cervical third (P = .04). In the middle third, G2/G3/G4 showed more debris than G1 (P = .03). The techniques were similar (P = .64) in the apical third. All groups presented filling debris in the 3 canal thirds after reinstrumentation.

A novel model for through-silicon via (TSV) filling process simulation considering three additives and current density effect

NASA Astrophysics Data System (ADS)

Wang, Fuliang; Zhao, Zhipeng; Wang, Feng; Wang, Yan; Nie, Nantian

2017-12-01

Through-silicon via (TSV) filling by electrochemical deposition is still a challenge for 3D IC packaging, and three-component additive systems (accelerator, suppressor, and leveler) were commonly used in the industry to achieve void-free filling. However, models considering three additive systems and the current density effect have not been fully studied. In this paper, a novel three-component model was developed to study the TSV filling mechanism and process, where the interaction behavior of the three additives (accelerator, suppressor, and leveler) were considered, and the adsorption, desorption, and consumption coefficient of the three additives were changed with the current density. Based on this new model, the three filling types (seam void, ‘V’ shape, and key hole) were simulated under different current density conditions, and the filling results were verified by experiments. The effect of the current density on the copper ion concentration, additives surface coverage, and local current density distribution during the TSV filling process were obtained. Based on the simulation and experimental results, the diffusion-adsorption-desorption-consumption competition behavior between the suppressor, the accelerator, and the leveler were discussed. The filling mechanisms under different current densities were also analyzed.

Kinetic and metabolic isotope effects in coral skeletal carbon isotopes: A re-evaluation using experimental coral bleaching as a case study

NASA Astrophysics Data System (ADS)

Schoepf, Verena; Levas, Stephen J.; Rodrigues, Lisa J.; McBride, Michael O.; Aschaffenburg, Matthew D.; Matsui, Yohei; Warner, Mark E.; Hughes, Adam D.; Grottoli, Andréa G.

2014-12-01

Coral skeletal δ13C can be a paleo-climate proxy for light levels (i.e., cloud cover and seasonality) and for photosynthesis to respiration (P/R) ratios. The usefulness of coral δ13C as a proxy depends on metabolic isotope effects (related to changes in photosynthesis) being the dominant influence on skeletal δ13C. However, it is also influenced by kinetic isotope effects (related to calcification rate) which can overpower metabolic isotope effects and thus compromise the use of coral skeletal δ13C as a proxy. Heikoop et al. (2000) proposed a simple data correction to remove kinetic isotope effects from coral skeletal δ13C, as well as an equation to calculate P/R ratios from coral isotopes. However, despite having been used by other researchers, the data correction has never been directly tested, and isotope-based P/R ratios have never been compared to P/R ratios measured using respirometry. Experimental coral bleaching represents a unique environmental scenario to test this because bleaching produces large physiological responses that influence both metabolic and kinetic isotope effects in corals. Here, we tested the δ13C correction and the P/R calculation using three Pacific and three Caribbean coral species from controlled temperature-induced bleaching experiments where both the stable isotopes and the physiological variables that cause isotopic fractionation (i.e., photosynthesis, respiration, and calcification) were simultaneously measured. We show for the first time that the data correction proposed by Heikoop et al. (2000) does not effectively remove kinetic effects in the coral species studied here, and did not improve the metabolic signal of bleached and non-bleached corals. In addition, isotope-based P/R ratios were in poor agreement with measured P/R ratios, even when the data correction was applied. This suggests that additional factors influence δ13C and δ18O, which are not accounted for by the data correction. We therefore recommend that the data correction not be routinely applied for paleo-climate reconstruction, and that P/R ratios should only be obtained by direct measurement by respirometry.

Inertia gravity waves in a rotating, differentially heated annulus with an upper free surface

NASA Astrophysics Data System (ADS)

Randriamampianina, Anthony; Harlander, Uwe; Vincze, Miklos; von Larcher, Thomas; Viazzo, Stephane

2015-04-01

Inertia gravity waves (IGWs) are ubiquitous in the atmosphere and oceans, and are known to play a fundamental role in a wide variety of processes, among others the induction and modulation of turbulence. Observations and simulations have revealed their spontaneous occurrence simultaneously with the onset of baroclinic instability, recognized to be one of the dominant energetic processes in the large-scale atmospheric and oceanic circulations. In spite of intensive research activities these last decades, the generation mechanism and the propagation of IGWs, as well as their interaction with large-scale structures triggering locally chaotic motions, remain poorly understood. A better understanding of these phenomena is therefore mandatory for the development of IGW's parameterization schemes actually required for numerical global weather prediction. A combined laboratory experiment and direct numerical simulations study is proposed for the detailed investigations of instabilities arising within a differentially heated rotating annulus, the baroclinic cavity. The configuration corresponds to an experimental setup used at BTU, Cottbus Senftenberg, Germany [1], characterized by an open upper surface and filled with water (Pr = 7). Infrared thermography and simultaneous kalliroscope visualization in horizontal planes, illuminated by a laser sheet, have been applied to detect the surface signatures of IGWs. These findings confirmed the computations carried out by three different numerical approaches, using either spectral methods, high order compact finite difference scheme (M2P2, Marseille), or the EULAG code (Freie Universitaet Berlin). These small-scale features have been observed in addition to those developing along the inner cold cylinder, previously identified by simulations in a closed cavity, filled with a liquid defined by Pr = 16 [2]. These new IGWs show characteristics similar to the ones obtained by [3] at the exit of the meandering jet between the cyclonic and anticyclonic parts of the baroclinic waves. References [1] Harlander, U. et al. Exp. Fluids 52:1077-1087, 2012. [2] Randriamampianina, A. C. R. M'ecanique 341:547-552, 2013. [3] Plougonven, R. & Snyder, C. J. Atmos Sci. 64:2502-2520, 2007.

Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

PubMed

Chadda, Harshita; Naveen, Sangeetha Vasudevaraj; Mohan, Saktiswaren; Satapathy, Bhabani K; Ray, Alok R; Kamarul, Tunku

2016-07-01

Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail. The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination. Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software. Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis. The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

The Structural Architecture of an Infectious Mammalian Prion Using Electron Cryomicroscopy.

PubMed

Vázquez-Fernández, Ester; Vos, Matthijn R; Afanasyev, Pavel; Cebey, Lino; Sevillano, Alejandro M; Vidal, Enric; Rosa, Isaac; Renault, Ludovic; Ramos, Adriana; Peters, Peter J; Fernández, José Jesús; van Heel, Marin; Young, Howard S; Requena, Jesús R; Wille, Holger

2016-09-01

The structure of the infectious prion protein (PrPSc), which is responsible for Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy, has escaped all attempts at elucidation due to its insolubility and propensity to aggregate. PrPSc replicates by converting the non-infectious, cellular prion protein (PrPC) into the misfolded, infectious conformer through an unknown mechanism. PrPSc and its N-terminally truncated variant, PrP 27-30, aggregate into amorphous aggregates, 2D crystals, and amyloid fibrils. The structure of these infectious conformers is essential to understanding prion replication and the development of structure-based therapeutic interventions. Here we used the repetitive organization inherent to GPI-anchorless PrP 27-30 amyloid fibrils to analyze their structure via electron cryomicroscopy. Fourier-transform analyses of averaged fibril segments indicate a repeating unit of 19.1 Å. 3D reconstructions of these fibrils revealed two distinct protofilaments, and, together with a molecular volume of 18,990 Å3, predicted the height of each PrP 27-30 molecule as ~17.7 Å. Together, the data indicate a four-rung β-solenoid structure as a key feature for the architecture of infectious mammalian prions. Furthermore, they allow to formulate a molecular mechanism for the replication of prions. Knowledge of the prion structure will provide important insights into the self-propagation mechanisms of protein misfolding.

Access to healthcare, HIV/STI testing, and preferred pre-exposure prophylaxis providers among men who have sex with men and men who engage in street-based sex work in the US.

PubMed

Underhill, Kristen; Morrow, Kathleen M; Colleran, Christopher M; Holcomb, Richard; Operario, Don; Calabrese, Sarah K; Galárraga, Omar; Mayer, Kenneth H

2014-01-01

Pre-exposure prophylaxis (PrEP) is a promising strategy for HIV prevention among men who have sex with men (MSM) and men who engage in sex work. But access will require routine HIV testing and contacts with healthcare providers. This study investigated men's healthcare and HIV testing experiences to inform PrEP implementation. We conducted 8 focus groups (n = 38) in 2012 and 56 in-depth qualitative interviews in 2013-14 with male sex workers (MSWs) (n = 31) and other MSM (n = 25) in Providence, RI. MSWs primarily met clients in street-based sex work venues. Facilitators asked participants about access to healthcare and HIV/STI testing, healthcare needs, and preferred PrEP providers. MSWs primarily accessed care in emergency rooms (ERs), substance use clinics, correctional institutions, and walk-in clinics. Rates of HIV testing were high, but MSWs reported low access to other STI testing, low insurance coverage, and unmet healthcare needs including primary care, substance use treatment, and mental health services. MSM not engaging in sex work were more likely to report access to primary and specialist care. Rates of HIV testing among these MSM were slightly lower, but they reported more STI testing, more insurance coverage, and fewer unmet needs. Preferred PrEP providers for both groups included primary care physicians, infectious disease specialists, and psychiatrists. MSWs were also willing to access PrEP in substance use treatment and ER settings. PrEP outreach efforts for MSWs and other MSM should engage diverse providers in many settings, including mental health and substance use treatment, ERs, needle exchanges, correctional institutions, and HIV testing centers. Access to PrEP will require financial assistance, but can build on existing healthcare contacts for both populations.

Access to Healthcare, HIV/STI Testing, and Preferred Pre-Exposure Prophylaxis Providers among Men Who Have Sex with Men and Men Who Engage in Street-Based Sex Work in the US

PubMed Central

Underhill, Kristen; Morrow, Kathleen M.; Colleran, Christopher M.; Holcomb, Richard; Operario, Don; Calabrese, Sarah K.; Galárraga, Omar; Mayer, Kenneth H.

2014-01-01

Background Pre-exposure prophylaxis (PrEP) is a promising strategy for HIV prevention among men who have sex with men (MSM) and men who engage in sex work. But access will require routine HIV testing and contacts with healthcare providers. This study investigated men’s healthcare and HIV testing experiences to inform PrEP implementation. Methods We conducted 8 focus groups (n = 38) in 2012 and 56 in-depth qualitative interviews in 2013–14 with male sex workers (MSWs) (n = 31) and other MSM (n = 25) in Providence, RI. MSWs primarily met clients in street-based sex work venues. Facilitators asked participants about access to healthcare and HIV/STI testing, healthcare needs, and preferred PrEP providers. Results MSWs primarily accessed care in emergency rooms (ERs), substance use clinics, correctional institutions, and walk-in clinics. Rates of HIV testing were high, but MSWs reported low access to other STI testing, low insurance coverage, and unmet healthcare needs including primary care, substance use treatment, and mental health services. MSM not engaging in sex work were more likely to report access to primary and specialist care. Rates of HIV testing among these MSM were slightly lower, but they reported more STI testing, more insurance coverage, and fewer unmet needs. Preferred PrEP providers for both groups included primary care physicians, infectious disease specialists, and psychiatrists. MSWs were also willing to access PrEP in substance use treatment and ER settings. Conclusions PrEP outreach efforts for MSWs and other MSM should engage diverse providers in many settings, including mental health and substance use treatment, ERs, needle exchanges, correctional institutions, and HIV testing centers. Access to PrEP will require financial assistance, but can build on existing healthcare contacts for both populations. PMID:25386746

Le syndrome d'embolie graisseuse post traumatique

PubMed Central

Berdai, Adnane Mohamed; Shimi, Abdelkarim; Khatouf, Mohammed

2014-01-01

Le syndrome d'embolie graisseuse est une complication grave des fractures des os longs, il est la conséquence de la dissémination des particules graisseuses dans la microcirculation. L'objectif de ce travail est de déterminer le profil épidémiologique, la présentation clinique et paraclinique de ce syndrome et sa prise en charge thérapeutique. Notre étude porte sur 11 cas de syndrome d'embolie graisseuse colligés au service de réanimation A1 au centre hospitalier universitaire Hassan II de Fès, de Janvier 2009 à Juin 2012. Le diagnostic positif est basé sur les critères de Gurd. Les cas collectés se caractérisent par la prédominance du sexe masculin, d'un âge inférieur à 40 ans, présentant une fracture fémorale. Ce syndrome survient souvent dans les 72 heures après le traumatisme. La présentation clinique est dominée par l'hypoxémie et les troubles de conscience. Sur le plan biologique: l'anémie et la thrombopénie sont les manifestations les plus fréquentes. La prise en charge est symptomatique, 63% des patients ont nécessité l'intubation et la ventilation. L’évolution n'est pas toujours bénigne. Nos résultats confirme le polymorphisme de la présentation clinique et paraclinique du syndrome d'embolie graisseuse. Le diagnostic de ce syndrome se base sur des critères cliniques, mais reste essentiellement un diagnostic d’élimination. La prise en charge est symptomatique. La prévention de ce syndrome est essentielle et se base sur une fixation précoce des fractures des os longs. PMID:25452829

Sexual behavior and associated factors in rural adolescents.

PubMed

Sousa, Bárbara Cabral de; Santos, Rebeca Silva Dos; Santana, Katiuscy Carneiro; Souzas, Raquel; Leite, Álvaro Jorge Madeiro; Medeiros, Danielle Souto de

2018-01-01

To describe the sexual behavior and to identify associated factors in adolescents from rural communities in Bahia, Brazil. This is a cross-sectional, population-based, and household-based study, carried out in 2015 with adolescents aged 10 to 19 years. We described the variables of sexual intercourse in life and in the last 12 months, age at first intercourse, condom use and number of partners, guidance on pregnancy, AIDS, or other sexually transmitted infections, and guidance on how to get condoms. The analysis was performed for the total sample and for the quilombola and nonquilombola strata. We used Poisson regression, with robust variance, to estimate the prevalence ratios for sexual intercourse in relation to the explanatory variables. A total of 390 adolescents were interviewed, of them 42.8% were quilombolas, 51.3% females, and the median age was 14.8 years. Of these adolescents, 26.4% reported sexual intercourse (28.1% quilombolas and 25.1% non-quilombolas), and the median age of the first relation was 15 years; 77.7% of them mentioned condom use in the last intercourse and more than half received guidance on pregnancy, AIDS, or other sexually transmitted infections and received no guidance on how to get free condoms. Age (PR = 1.42) and alcohol use experimentation (PR = 2.41) were positively associated with sexual intercourse after adjustment. In the quilombola stratum, age (RP = 1.37), having three or more close friends (PR = 1.37), and experimentation with alcohol (PR = 2.60) were associated. In the non-quilombola stratum, age (PR = 1.43), black persons (PR = 2.06), and alcohol use experimentation (PR = 2.68) were associated. Lack of information and exposure to behaviors such as alcohol use experimentation are conditions that need to be addressed in health promotion strategies and in strategies for the prevention of sexual health problems in rural adolescents. Intersectoral partnerships between education and health also need to be strengthened to promote the autonomous and safe exercise of sexuality in this population.

Neodymium-140 DOTA-LM3: Evaluation of an In Vivo Generator for PET with a Non-Internalizing Vector.

PubMed

Severin, Gregory W; Kristensen, Lotte K; Nielsen, Carsten H; Fonslet, Jesper; Jensen, Andreas I; Frellsen, Anders F; Jensen, K M; Elema, Dennis R; Maecke, Helmut; Kjær, Andreas; Johnston, Karl; Köster, Ulli

2017-01-01

140 Nd ( t 1/2  = 3.4 days), owing to its short-lived positron emitting daughter 140 Pr ( t 1/2  = 3.4 min), has promise as an in vivo generator for positron emission tomography (PET). However, the electron capture decay of 140 Nd is chemically disruptive to macrocycle-based radiolabeling, meaning that an in vivo redistribution of the daughter 140 Pr is expected before positron emission. The purpose of this study was to determine how the delayed positron from the de-labeled 140 Pr affects preclinical imaging with 140 Nd. To explore the effect, 140 Nd was produced at CERN-ISOLDE, reacted with the somatostatin analogue, DOTA-LM3 (1,4,7,10- tetraazacyclododecane, 1,4,7- tri acetic acid, 10- acetamide N - p-Cl-Phecyclo(d-Cys-Tyr-d-4-amino-Phe(carbamoyl)-Lys-Thr-Cys)d-Tyr-NH2) and injected into H727 xenograft bearing mice. Comparative pre- and post-mortem PET imaging at 16 h postinjection was used to quantify the in vivo redistribution of 140 Pr following 140 Nd decay. The somatostatin receptor-positive pancreas exhibited the highest tissue accumulation of 140 Nd-DOTA-LM3 (13% ID/g at 16 h) coupled with the largest observed redistribution rate, where 56 ± 7% ( n  = 4, mean ± SD) of the in situ produced 140 Pr washed out of the pancreas before decay. Contrastingly, the liver, spleen, and lungs acted as strong sink organs for free 140 Pr 3+ . Based upon these results, we conclude that 140 Nd imaging with a non-internalizing vector convolutes the biodistribution of the tracer with the accumulation pattern of free 140 Pr. This redistribution phenomenon may show promise as a probe of the cellular interaction with the vector, such as in determining tissue dependent internalization behavior.

Understanding the Low Level of Cervical Cancer Screening in Masaka Uganda Using the ASE Model: A Community-Based Survey.

PubMed

Twinomujuni, Cyprian; Nuwaha, Fred; Babirye, Juliet Ndimwibo

2015-01-01

Cervical cancer is one of the leading causes of cancer deaths among women globally and its impact is mostly felt in developing countries like Uganda where its prevalence is higher and utilization of cancer screening services is low. This study aimed to identify factors associated with intention to screen for cervical cancer among women of reproductive age in Masaka Uganda using the attitude, social influence and self efficacy (ASE) model. A descriptive community based survey was conducted among 416 women. A semi-structured interviewer administered questionnaire was used to collect data. Unadjusted and adjusted prevalence ratios (PR) were computed using a generalized linear model with Poisson family and a log link using STATA 12. Only 7% (29/416) of our study respondents had ever screened for cervical cancer although a higher proportion (63%, 262/416) reported intention to screen for cervical cancer. The intention to screen for cervical cancer was higher among those who said they were at risk of developing cervical cancer (Adjusted prevalence ratio [PR] 2.0, 95% CI 1.60-2.58), those who said they would refer other women for screening (Adjusted PR 1.4, 95% CI 1.06-1.88) and higher among those who were unafraid of being diagnosed with cervical cancer (Adjusted PR 1.6, 95% CI 1.36-1.93). Those who reported discussions on cervical cancer with health care providers (Adjusted PR 1.2, 95% CI 1.05-1.44), those living with a sexual partner (Adjusted PR 1.4, 95% CI 1.11-1.68), and those who were formally employed (Adjusted PR 1.2, 95% CI 1.03-1.35) more frequently reported intention to screen for cervical cancer. In conclusion, health education to increase risk perception, improve women's attitudes towards screening for cervical cancer and address the fears held by the women would increase intention to screen for cervical cancer. Interventions should also target increased discussions with health workers.

Neodymium-140 DOTA-LM3: Evaluation of an In Vivo Generator for PET with a Non-Internalizing Vector

PubMed Central

Severin, Gregory W.; Kristensen, Lotte K.; Nielsen, Carsten H.; Fonslet, Jesper; Jensen, Andreas I.; Frellsen, Anders F.; Jensen, K. M.; Elema, Dennis R.; Maecke, Helmut; Kjær, Andreas; Johnston, Karl; Köster, Ulli

2017-01-01

140Nd (t1/2 = 3.4 days), owing to its short-lived positron emitting daughter 140Pr (t1/2 = 3.4 min), has promise as an in vivo generator for positron emission tomography (PET). However, the electron capture decay of 140Nd is chemically disruptive to macrocycle-based radiolabeling, meaning that an in vivo redistribution of the daughter 140Pr is expected before positron emission. The purpose of this study was to determine how the delayed positron from the de-labeled 140Pr affects preclinical imaging with 140Nd. To explore the effect, 140Nd was produced at CERN-ISOLDE, reacted with the somatostatin analogue, DOTA-LM3 (1,4,7,10- tetraazacyclododecane, 1,4,7- tri acetic acid, 10- acetamide N - p-Cl-Phecyclo(d-Cys-Tyr-d-4-amino-Phe(carbamoyl)-Lys-Thr-Cys)d-Tyr-NH2) and injected into H727 xenograft bearing mice. Comparative pre- and post-mortem PET imaging at 16 h postinjection was used to quantify the in vivo redistribution of 140Pr following 140Nd decay. The somatostatin receptor-positive pancreas exhibited the highest tissue accumulation of 140Nd-DOTA-LM3 (13% ID/g at 16 h) coupled with the largest observed redistribution rate, where 56 ± 7% (n = 4, mean ± SD) of the in situ produced 140Pr washed out of the pancreas before decay. Contrastingly, the liver, spleen, and lungs acted as strong sink organs for free 140Pr3+. Based upon these results, we conclude that 140Nd imaging with a non-internalizing vector convolutes the biodistribution of the tracer with the accumulation pattern of free 140Pr. This redistribution phenomenon may show promise as a probe of the cellular interaction with the vector, such as in determining tissue dependent internalization behavior. PMID:28748183

3. View of partially excavated mill ruins looking NW showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View of partially excavated mill ruins looking NW showing unidentified pit in right foreground, masonry base for steam engine and cane mill in left center, purging house and chimney in background. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR

Development of an Assay for the Detection of PrPres in Blood and Urine Based on PMCA Assay and ELISA Methods

DTIC Science & Technology

2007-09-01

practically have dropped the collaboration with Biotraces as the company was not able to provide us with an improved version of their instrument...Although the claimed sensitivity was reproduced in studies conducted at BioTraces with recombinant PrP. The question was whether the same sensitivity

Recognising Workplace Learning: The Emerging Practices of e-RPL and e-PR

ERIC Educational Resources Information Center

Cameron, Roslyn

2012-01-01

Purpose: The use of e-portfolios in recognition of prior learning (RPL) processes in workplace and professional practice contexts has attracted little attention in the literature due to its emergent nature. This study seeks to explore the growing incidence of e-portfolio-based RPL (e-RPL) and professional recognition (e-PR) processes in Australia…

Sphingosine-1-phosphate receptor 1 regulates neointimal growth in a humanized model for restenosis.

PubMed

Braetz, Julian; Becker, Astrid; Geissen, Markus; Larena-Avellaneda, Axel; Schrepfer, Sonja; Daum, Guenter

2018-05-24

The main objective of this study was to define a role of sphingosine-1-phosphate receptor 1 (S1PR1) in the arterial injury response of a human artery. The hypotheses were tested that injury induces an expansion of S1PR1-positive cells and that these cells accumulate toward the lumen because they follow the sphingosine-1-phosphate gradient from arterial wall tissue (low) to plasma (high). A humanized rat model was used in which denuded human internal mammary artery (IMA) was implanted into the position of the abdominal aorta of immunosuppressed Rowett nude rats. This injury model is characterized by medial as well as intimal hyperplasia, whereby intimal cells are of human origin. At 7, 14, and 28 days after implantation, grafts were harvested and processed for fluorescent immunostaining for S1PR1 and smooth muscle α-actin. Nuclei were stained with 4',6-diamidine-2'-phenylindole dihydrochloride. Using digitally reconstructed, complete cross sections of grafts, intimal and medial areas were measured, whereby the medial area had virtually been divided into an outer (toward adventitia) and inner (toward lumen) layer. The fraction of S1PR1-positive cells was determined in each layer by counting S1PR1-positive and S1PR1-negative cells. The fraction of S1PR1-postive cells in naive IMA is 58.9% ± 6.0% (mean ± standard deviation). At day 28 after implantation, 81.6% ± 4.4% of medial cells were scored S1PR1 positive (P < .01). At day 14, the ratio between S1PR1-positive and S1PR1-negative cells was significantly higher in the lumen-oriented inner layer (9.3 ± 2.1 vs 6.0 ± 1.0; P < .01). Cells appearing in the intima at day 7 and day 14 were almost all S1PR1 positive. At day 28, however, about one-third of intimal cells were scored S1PR1 negative. From these data, we conclude that denudation of IMA specifically induces the expansion of S1PR1-positive cells. Based on the nonrandom distribution of S1PR1-positive cells, we consider the possibility that much like lymphocytes, S1PR1-positive smooth muscle cells also use S1PR1 to recognize the sphingosine-1-phosphate gradient from tissue (low) to plasma (high) and so migrate out of the media toward the intima of the injured IMA. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Identification of Risk Factors for the Development of Pressure Ulcers Despite Standard Screening Methodology and Prophylaxis in Trauma Patients.

PubMed

Raff, Lauren A; Waller, Holly; Griffin, Russell L; Kerby, Jeffrey D; Bosarge, Patrick L

2016-07-01

To present information about a study of risk factors for development of pressure ulcers (PrUs) in trauma patients. This continuing education activity is intended for physicians and nurses with an interest in skin and wound care. After participating in this educational activity, the participant should be better able to:1. Describe the previous PrU research, scope of the problem, and methodology of the study.2. Explain the results of the study identifying PrU risk factors for trauma patients. Pressure ulceration prevention has been emphasized  over the past several years in inpatient hospital settings with  subsequent decreases in the development of pressure ulcers (PrUs).  However, there remains a subset of trauma and burn patients  that develop PrUs despite standard screening methodology and  prophylaxis. This study determines the conditions that predict  development of pressure ulcers (PrUs) despite conventional  prophylaxis and screening.  Demographic and PrU data were collected over a  5-year period from June 2008 to May 2013. Patients diagnosed  with PrUs upon arrival in the trauma bay were excluded from  analysis. An ordinal logistic regression of PrU stage was used to  estimate odds ratios (ORs) and associated 95% confidence intervals  (CIs) for the association between characteristics of interest and  odds of a PrU. A backward selection process was used to select the  most parsimonious model.  During the study period, 14,616 trauma patients were  admitted and had available data. A total of 124 patients (0.85%) that met inclusion criteria went on to develop PrUs during their hospital course. Factors associated with the development of PrUs included spine Abbreviated Injury Scale (AIS) >3 (OR, 5.72; CI, 3.63-9.01), mechanical ventilation (OR, 1.95; CI, 1.23-3.10) and age 40 to 64 (OR, 2.09; CI, 1.24-3.52) and age ≥ 65 (OR, 4.48; CI, 2.52-7.95). Interestingly, head injury AIS >3 was protective from the development of PrUs (OR, 0.56; CI, 0.32-0.96). Hypotension and shock defined as systolic BP <90 mm Hg and base deficit less than -6 were not associated with the development of PrUs. In addition, body mass index was not associated with PrU development.  Spinal injuries, older than age 40, and mechanical  ventilation predict the development of PrUs for a subset of  patients, despite conventional prophylaxis and screening. Advanced  prevention methods, such as low-air-loss mattresses for these patient  subgroups should be considered immediately upon identification  of these risk factors during the hospital course.

Crystal growth patterns in DC and pulsed plated galvanic copper films on (1 1 1), (1 0 0) and (1 1 0) copper surfaces

NASA Astrophysics Data System (ADS)

Brown, Delilah A.; Morgan, Sean; Peldzinski, Vera; Brüning, Ralf

2017-11-01

Copper films for printed circuit board applications have to be fine-grained to achieve even filling of vias. Electroplated Cu films on roll annealed Cu substrates may have unacceptably large epitaxial crystals. Here galvanic films were plated on oriented single-crystal Cu substrates from an additive-free electrolyte, as well as DC plating and pulse reverse (PR) plating with additives. The distribution of crystallite orientations was mapped with XRD and compared with the microstructure determined by SEM. For the additive-free bath on [1 1 1] and [1 0 0] oriented surfaces a gradual transition from epitaxial to polycrystalline is seen, while films on [1 1 0] substrates are persistently epitaxial. Without bath additives, twinning is the main mechanism for the transition to polycrystalline texture. For DC plating, additives (carriers, accelerators and levelers) promote fine-grained films with isotropic grain orientations, with films on [1 1 0] substrates being partially isotropic. Plating with carriers and accelerators (no leveler) yields films with many distinct crystallite orientations. These orientations result from up to five steps of recursive twinning. PR plating produces isotropic films with no or very few twins (〈1 1 1〉 and 〈1 0 0〉 substrates, respectively), while on 〈1 1 0〉 oriented surfaces the deposits are about 20% epitaxial.

Syntheses, structures, and physical properties of CsRE(2)Ag(3)Te(5) (RE = Pr, Nd, Sm, Gd-Er) and RbR(2)Ag(3)Te(5) (RE = Sm, Gd-Dy).

PubMed

Meng, Chang-Yu; Chen, Hong; Wang, Peng

2014-07-07

A new series of quaternary CsRE2Ag3Te5 (RE = Pr, Nd, Sm, Gd-Er) and RbRE2Ag3Te5 (RE = Sm, Gd-Dy), which have been synthesized from the elemental mixtures in ACl flux (A = Rb, Cs) and crystallized in the orthorhombic space group Cmcm, with a = 4.620(2)-4.504(2) Å, b = 16.232(8)-16.027(8) Å, c = 18.84(1)-18.32(2) and Z = 4, are isostructural to RbSm2Ag3Se5. These isostructural ARE2Ag3Te5 feature a three-dimensional tunnel framework constructed by ionically bound RETe6 octahedron and covalently bound AgTe4 tetrahedron in which tunnels are filled by A. Typical semiconducting behavior is revealed by the electrical conductivity, Seebeck coefficient, optical band gap measurement, and the theoretical calculations. The undoped sintered polycrystalline pellets of CsRE2Ag3Te5 (containing 1.1-1.7% CsCl impurity) show very low electrical conductivity (σr.t. = 0.5-2.4 S/cm), very low thermal conductivity (kr,t = 0.66-0.53 W/(m·K)), and moderate Seebeck coefficient (160-200 μV/K at 700 K).

Facilitators and Barriers to Pre-Exposure Prophylaxis Willingness Among Young Men Who Have Sex with Men Who Use Geosocial Networking Applications in California.

PubMed

Holloway, Ian W; Tan, Diane; Gildner, Jennifer L; Beougher, Sean C; Pulsipher, Craig; Montoya, Jorge A; Plant, Aaron; Leibowitz, Arleen

2017-12-01

While correlates of pre-exposure prophylaxis (PrEP) uptake have been explored among older men who have sex with men (MSM), less is known about the facilitators and barriers that encourage uptake among younger MSM (YMSM). This study explores the association between willingness to take PrEP and demographic characteristics, sexual risk, and substance use, and attitudinal factors among YMSM in California who use geosocial networking applications (GSN apps). Based on survey data from YMSM recruited through GSN apps (n = 687), PrEP willingness was positively associated with Hispanic ethnicity [adjusted odds ratio (aOR): 1.73; confidence interval (CI): 1.01-2.98; p = 0.046], concerns about drug effects (aOR: 0.46; CI: 0.33-0.65; p < 0.001), medical mistrust (aOR: 0.71; CI: 0.53-0.96; p < 0.001), and concerns about adherence (aOR: 0.65; CI: 0.49-0.89; p = 0.005). PrEP willingness was positively associated with medium (aOR: 1.87; CI: 1.14-3.07; p = 0.014) and high concern (aOR: 1.84; CI: 1.13-3.01; p < 0.001) about contracting HIV and perceived benefits of taking PrEP (aOR: 2.59; CI: 1.78-3.78; p < 0.001). In addition to emphasizing the benefits of using PrEP, campaigns that address concerns regarding adherence and side effects may increase interest in and demand for PrEP among YMSM. More opportunities are needed to educate YMSM about PrEP, including addressing their concerns about this new prevention strategy. Providers should speak openly and honestly to YMSM considering PrEP about what to do if side effects occur and how to handle missed doses. Outreach using GSN apps for PrEP education and screening may be an effective way to reach YMSM.

A new rapid method for direct antimicrobial susceptibility testing of bacteria from positive blood cultures.

PubMed

Barnini, Simona; Brucculeri, Veronica; Morici, Paola; Ghelardi, Emilia; Florio, Walter; Lupetti, Antonella

2016-08-12

Rapid identification and antimicrobial susceptibility testing (AST) of the causative agent(s) of bloodstream infections can lead to prompt appropriate antimicrobial therapy. To shorten species identification, in this study bacteria were recovered from monomicrobial blood cultures by serum separator tubes and spotted onto the target plate for direct MALDI-TOF MS identification. Proper antibiotics were selected for direct AST based on species identification. In order to obtain rapid AST results, bacteria were recovered from positive blood cultures by two different protocols: by serum separator tubes (further referred to as PR1), or after a short-term subculture in liquid medium (further referred to as PR2). The results were compared with those obtained by the method currently used in our laboratory consisting in identification by MALDI-TOF and AST by Vitek 2 or Sensititre on isolated colonies. The direct MALDI-TOF method concordantly identified with the current method 97.5 % of the Gram-negative bacteria and 96.1 % of the Gram-positive cocci contained in monomicrobial blood cultures. The direct AST by PR1 and PR2 for all isolate/antimicrobial agent combinations was concordant/correct with the current method for 87.8 and 90.5 % of Gram-negative bacteria and for 93.1 and 93.8 % of Gram-positive cocci, respectively. In particular, 100 % categorical agreement was found with levofloxacin for Enterobacteriaceae by both PR1 and PR2, and 99.0 and 100 % categorical agreement was observed with linezolid for Gram-positive cocci by PR1 and PR2, respectively. There was no significant difference in accuracy between PR1 and PR2 for Gram-negative bacteria and Gram-positive cocci. This newly described method seems promising for providing accurate AST results. Most importantly, these results would be available in a few hours from blood culture positivity, which would help clinicians to promptly confirm or streamline an effective antibiotic therapy in patients with bloodstream infections.