Low thermal conductivity in A-site high entropy perovskite relaxor ferroelectric

An A-site disordered high entropy perovskite (Pb1/6Ba1/6Sr1/6Ca1/6Na1/6Bi1/6)TiO3 (PBSCNBi) ceramic was prepared by a solid-state reaction method. XRD and scanning electron microscopy-energy dispersive x ray confirmed a single-phase tetragonal solid solution. Dielectric and hysteresis loop measurements showed relaxor ferroelectricity at room temperature; Curie Weiss fitting gives a Burns temperature (Tb) of 123 °C, and Vogel-Fulcher fitting gives a freezing temperature (Tf) of -67.24 °C, which confirms the room-temperature relaxor ferroelectricity of PBSCNBi. This is attributed to local chemical inhomogeneities in the high entropy ceramics. PBSCNBi also has a low thermal conductivity (1.15 W m-1 K-1 at room temperature) compared to all of its constituent simple perovskites (e.g., BaTiO3, PbTiO3, SrTiO3 CaTiO3, and Na1/2Bi1/2TiO3 in the range of 25-100 °C), which is attributed to the enhanced phonon scattering by both polar nanoregions and the mass contrast effect in the multi-element perovskite. This work demonstrates the great potential of making A-site high entropy ceramics with relaxor ferroelectric properties

Constraints on DD Dimensional Warped Spaces

In order to investigate the phenomenological implications of allowing gauge fields to propagate in warped spaces of more than five dimensions, we consider a toy model of a space warped by the presence of a anisotropic bulk cosmological constant. After solving the Einstein equation, three classes of solutions are found, those in which the additional ($D>5$) dimensions are growing, shrinking or remaining constant. It is found that gauge fields propagating in these spaces have a significantly different Kaluza Klein (KK) mass spectrum and couplings from that of the Randall and Sundrum model. This leads to a greatly reduced lower bound on the KK scale, arising from electroweak constraints, for spaces growing towards the IR brane.Comment: 6 pages, 5 figures PASCOS2010 International Symposium proceedin

Performance and Potential of Intergeneric Wheatgrass Hybrids in the Central Great Plains

Three studies were conducted to evaluate intergeneric wheatgrass hybrids for their potential as range and pasture grasses in the Central Great Plains. Quackgrass [Elytriga-repens (L.) Nevski] X bluebunch wheatgrass [Psueodoroegneria spicata (Pursh) A. LoveJ F5 hybrid lines (RS lines) developed by D.R. Dewey were grown in a space transplanted nursery at Lincoln, NE, to estimate genetic variability for forage yield and quality as measured by in vitro dry matter digestibility (IVDMD) and protein in the RS population. There was significant variability among the RS lines for all traits (broad-sense heritability H \u3e 0.5) except for first harvest IVDMD (H = 0.26). The highest yielding RS lines yielded only about half as much forage as \u27Slate\u27 intermediate wheatgrass [Thinopyron intermedium (Host) Barkworth and D.R. Dewey subsp. intermedium], which was included as a check. Slate intermediate wheatgrass, \u27Ruff crested wheatgrass [Agropyron cristatum (L.) Gaertner], \u27Nordan\u27 crested wheatgrass [A. desertorum (Fisch.) SchultesJ, RS-1 and RS-2 (quackgrass X bluebunch wheatgrass germplasm), and a quackgrass X A. desertorum hybrid designated as RD were then evaluated in sward nurseries in two environments (Mead and Alliance, NE) that differ widely in climate. Intermediate wheatgrass was clearly superior in forage yield and quality as measured by IVDMD in the eastern part (Mead) of the Central Great Plains. In the western part of this area (Alliance) intermediate and the crested wheatgrasses were equal or superior to the RS hybrids in forage yield and intermediate wheatgrass had higher IVDMD. The RD hybrid had lower yields than the other strains at both locations. Yields of the intergeneric wheatgrass hybrids could be improved by breeding to make them more competitive with intermediate and crested wheatgrasses. The same breeding effort could be used to improve these pure species for which substantial genetic variability for both yield and IVDMD has been previously documented and would probably result in greater overall progress. Forages from grasses grown at Mead in swards were analyzed using the detergent system of analyses and there was considerable variation among the grasses in fiber composition and digestibility of the fiber components even though the grasses were very similar in physiological maturity when harvested. The results suggest that there are genetic differences among these wheatgrasses in forage fiber composition and the digestibility of the fiber components

Isolation and Chemical Characterization of Petroleum Refinery Wastewater Fractions Acutely Lethal to Daphnia Magna

This study is concerned with the isolation and identification of the most toxic portion of petroleum refinery wastewaters. It is hoped that this study will aid the goal of decreasing the discharge of toxic wastewaters and thus contribute to a healthier aquatic environment.Zoolog

Cobalt-catalyzed Wagner–Meerwein rearrangements with concomitant nucleophilic hydrofluorination

The authors acknowledge funding from the Royal Society (University Research Fellowship URF\R1\180017 (CPJ) and associated Enhancement Award RGF\EA\181022 (CPJ and RHH)), and the EaSI-CAT Centre for Doctoral Training (RHH and NM).We report a cobalt-catalyzed Wagner-Meerwein rearrangement of gem-disubstituted allylarenes that generates fluoroalkane products with isolated yields up to 84%. Modification of the counteranion of the N-fluoropyridinium oxidant suggests the substrates undergo nucleophilic fluorination during the reaction. Subjecting the substrates to other known metal-mediated hydrofluorination procedures did not lead to observable 1,2-aryl migration. Thus, indicating the unique ability of these cobalt-catalyzed conditions to generate a sufficiently reactive electrophilic intermediate capable of promoting this Wagner-Meerwein rearrangement.Publisher PDFPeer reviewe

The Problem of Auto-Correlation in Parasitology

Explaining the contribution of host and pathogen factors in driving infection dynamics is a major ambition in parasitology. There is increasing recognition that analyses based on single summary measures of an infection (e.g., peak parasitaemia) do not adequately capture infection dynamics and so, the appropriate use of statistical techniques to analyse dynamics is necessary to understand infections and, ultimately, control parasites. However, the complexities of within-host environments mean that tracking and analysing pathogen dynamics within infections and among hosts poses considerable statistical challenges. Simple statistical models make assumptions that will rarely be satisfied in data collected on host and parasite parameters. In particular, model residuals (unexplained variance in the data) should not be correlated in time or space. Here we demonstrate how failure to account for such correlations can result in incorrect biological inference from statistical analysis. We then show how mixed effects models can be used as a powerful tool to analyse such repeated measures data in the hope that this will encourage better statistical practices in parasitology