Publications by authors named "Mullens B"

Article Synopsis
  • A detailed study on TlTcO, a potential nuclear waste matrix, shows a phase transition from orthorhombic to tetragonal below 600 K, consistent with earlier research using X-ray diffraction.
  • Observations from neutron powder diffraction revealed anomalies like large atomic displacements at low temperatures and a decrease in Tc-O bond distance with heating, suggesting changes in local structure symmetry.
  • Density functional theory supports a monoclinic model for better energy efficiency, indicating that Tl's lone pairs are 'frozen' at low temperatures but become active and cause structural shifts upon heating, affecting the material's overall properties.
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The structures and high-temperature phase transition of CaUNbO were studied in situ using synchrotron X-ray and neutron powder diffraction. Rietveld refinements provided an accurate description of the crystal structures of both the monoclinic fergusonite-type 2/ structure observed at room temperature and the tetragonal scheelite-type 4/ structure found at high temperatures. Bond valence sum analysis showed Nb to be octahedrally coordinated in the monoclinic fergusonite-type structure, akin to other NbO materials.

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Pair distribution function (PDF) analysis of the scheelite-type material PbWO reveals previously unidentified short-range structural distortions in the PbO polyhedra and WO tetrahedra not observed in the similarly structured CaWO. These local distortions are a result of the structural influence of the Pb 6s lone pair electrons. These are not evident from the Rietveld analysis of synchrotron X-ray or neutron powder diffraction data, nor do they strongly influence the X-ray PDF (XPDF).

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Scheelite-type metal oxides are a notable class of functional materials, with applications including ionic conductivity, photocatalysis, and the safe storage of radioactive waste. To further engineer these materials for specific applications, a detailed understanding of how their properties can change under different conditions is required─not just in the long-range average structure but also in the short-range local structure. This paper outlines a detailed investigation of the metal oxide CsReO, which exhibits an uncommon orthorhombic pseudo-scheelite-type structure at room temperature.

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The thermal transformation of the tetragonal-zircon (tz-) to tetragonal-scheelite (ts-)BiVO was studied by in situ synchrotron X-ray diffraction, thermogravimetric analysis, and Fourier-transformed infrared spectroscopy. Upon heating, the tetragonal zircon polymorph of BiVO (tz-BiVO) transitioned to the ts-polymorph between 693-773 K. Above 773 K, single phase ts-BiVO was observed before transitioning to the monoclinic fergusonite (mf-) polymorph upon cooling.

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parasitizes the blood-feeding midge . Most (84%) single mermithid infective second stage juveniles (J2) developed into adult females, while parasitism by multiple J2 yielded 97% male adults. Nematodes emerged from the midge larval host as adults and mated immediately; females were ovoviviparous.

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Solid-state syntheses are generally regarded as being slow, limited by transport, and, as such, are often only stopped to check the products after many hours at high temperature. Here, using a custom-designed reactor to rapidly initiate solid-state syntheses, we are able to capture the earliest stages of a reaction using X-ray scattering. For the reaction of TiO and LiCO to form spinel lithium titanate (LiTiO)─an anode material for fast-charging applications─we capture two distinct kinetic regimes, including fast initial kinetics in the first seconds-minutes of the reaction that account for significant product formation.

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Oxides exhibiting the scheelite-type structure are an important class of functional materials with notable applications in photocatalysis, luminescence, and ionic conductivity. Like all materials, understanding their atomic structure is fundamental to engineering their physical properties. This study outlines a detailed structural investigation of the scheelite-type oxide RbReO, which exhibits a rare long-range phase transition from 4/ to 4/ upon heating.

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The stereochemical activity of lone pair electrons plays a central role in determining the structural and electronic properties of both chemically simple materials such as HO, as well as more complex condensed phases such as photocatalysts or thermoelectrics. TlReO is a rare example of a non-magnetic material exhibiting a re-entrant phase transition and emphanitic behavior in the long-range structure. Here, we describe the role of the Tl 6s lone pair electrons in these unusual phase transitions and illustrate its tunability by chemical doping, which has broad implications for functional materials containing lone pair bearing cations.

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Tabanus variegatus F. 1805 has been called by the name Tabanus sulcifronsMacquart 1855 for over 80 yr; T. variegatus is one of the most common large horse flies attacking livestock in much of the southeastern U.

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Phase transition and high-temperature properties of NdNbO and NdTaO were studied in situ using powder neutron diffraction methods. Both oxides undergo a reversible phase transition from a monoclinic I2/a phase at low temperatures to a tetragonal I4/a phase at high temperatures. The phase transition has been investigated through analysis of the spontaneous strains and symmetry distortion modes.

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The availability of rapid, highly sensitive and specific molecular and serologic diagnostic assays, such as competitive enzyme-linked immunosorbent assay (cELISA), has expedited the diagnosis of emerging transboundary animal diseases, including bluetongue (BT) and African horse sickness (AHS), and facilitated more thorough characterisation of their epidemiology. The development of assays based on real-time, reverse-transcription polymerase chain reaction (RT-PCR) to detect and identify the numerous serotypes of BT virus (BTV) and AHS virus (AHSV) has aided in-depth studies of the epidemiology of BTV infection in California and AHSV infection in South Africa. The subsequent evaluation of pan-serotype, real-time, RT-PCR-positive samples through the use of serotype-specific RT-PCR assays allows the rapid identification of virus serotypes, reducing the need for expensive and time-consuming conventional methods, such as virus isolation and serotype-specific virus neutralisation assays.

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Article Synopsis
  • The study examines the effects of tantalum (Ta) doping on the crystal structures of orthoniobates SmNbO4 and HoNbO4 using high-resolution diffraction and Density-Functional Theory calculations.
  • It was found that as Ta content increases, the unit cell volume decreases, indicating that Ta has a smaller ionic radius than niobium (Nb); however, structural invariance was observed in the SmO8 polyhedra.
  • Additionally, while HoNb1-xTaxO4 formed a miscibility gap at lower temperatures, increasing the synthesis temperature resolved this issue, leading to significant findings about the structural differences and bonding characteristics between the Nb and Ta compounds.
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The long-range average and short-range local structures in the Tm(TiTm)O ( = 0.00-0.67) series were studied using a combination of diffraction and spectroscopic techniques.

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The two most economically important poultry ectoparasites are the northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), and the poultry red mite, Dermanyssus gallinae (De Geer). Both mites are obligate blood feeders but differ in where they reside. Sampling methods thus focus on-host, especially the vent feathers, for northern fowl mite and off-host, especially cracks and crevices near the nighttime roosting areas, for poultry red mite.

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The northern fowl mite (NFM) Ornithonyssus sylviarum Canestrini and Fanzago is a blood-feeding ectoparasite found on many wild bird species and is a pest of poultry in the United States. It is unknown where NFM infestations of poultry originate, which has made it difficult to establish preventative biosecurity or effective control. We used microsatellite markers to evaluate genetic variation within and among NFM populations to determine routes of introduction onto farms and long-term persistence.

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Background: Stable isotope labeling is a promising method for use in insect mark-capture and dispersal studies. Culicoides biting midges, which transmit several important animal pathogens, including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV), are small flies that develop in various semi-aquatic habitats. Previous Culicoides dispersal studies have suffered from the limitations of other labeling techniques, and an inability to definitively connect collected adult midges to specific immature development sites.

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Haematobia irritans (L.) (Diptera: Muscidae) were netted from pastured cattle in California over two summers, with the goal of documenting on-host sex ratios and mating success as they might vary with repellent applications. Sex ratios were calculated from 100 adults per herd per date, and mating status of females (n = 30 per herd per date) was assessed by dissection of spermathecae.

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Insecticidal fly baits are important tools for adult house fly, Musca domestica L. (Diptera: Muscidae), control, especially on animal operations. Two house fly baits, containing either cyantraniliprole or dinotefuran, were tested on a dairy farm for attractiveness over time compared to a sugar control.

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The egg and larval instars (L1-L4) of Culicoides sonorensis Wirth and Jones are described. Average (range) of body lengths of a laboratory colony (Van Ryn) were 0.45 (0.

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Light-baited suction traps are one of the most widely used tools for vector surveillance. Their popularity stems from ease of use even in remote locations, range and abundance of species caught, and low cost. The availability of smaller, portable models, like the CDC miniature light trap, have further increased their ubiquity in entomological field studies.

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California pastured cattle were treated with 250 ml of a 15% mixture of fatty acids (C8-C9-C10) or 125 ml of 2% geraniol in a mineral oil carrier to assess impacts on horn flies, Haematobia irritans (L.) (Diptera: Muscidae) over two summers. Horn flies were netted from cattle every 3-4 d for 2 wk before treatment, 2 wk during treatment (four treatments, with flies collected before each treatment), and 2 wk after treatments ceased.

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Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae) is a key bluetongue virus vector in the United States. Immatures occur in mud near the edges of wastewater ponds and are understudied targets for control efforts. Eggs of C.

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