bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the effect of suspensions nanostructure on the thermophysical properties of nanofluids
Authors: Tesfai Waka , Singh Pawan K. , Masharqa Salim J. S. , Souier Tewfik , Chiesa Matteo , Shatilla Youssef
Published: December 2012

The effect of fractal dimensions and Feret diameter of aggregated nanoparticle on predicting the thermophysical properties of nanofluids is demonstrated. The fractal dimensions and Feret diameter distributions of particle agglomerates are quantified from scanning electron and probe microscope imaging of yttria nanofluids. The results are compared with the fractal dimensions calculated by fitting the rheological properties of yttria nanofluids against the modified Krieger-Dougherty model. Nanofluids of less than 1 vol. % particle loading are found to have fractal dimensions of below 1.8, which is typical for diffusion controlled cluster formation. By contrast, an increase in the particle loading increases the fractal dimension to 2.0–2.2. The fractal dimensions obtained from both methods are employed to predict the thermal conductivity of the nanofluids using the modified Maxwell-Garnet (M-G) model. The prediction from rheology is found inadequate and might lead up to 8% error in thermal conductivity for an improper choice of aspect ratio. Nevertheless, the prediction of the modified M-G model from the imaging is found to agree well with the experimentally observed effective thermal conductivity of the nanofluids. In addition, this study opens a new window on the study of aggregate kinetics, which is critical in tuning the properties of multiphase systems.
Thin waveguides with Robin boundary conditions
Authors: Bouchitté Guy , Mascarenhas Luísa , Trabucho Luís
Published: December 2012

We consider the Laplace operator in a thin three-dimensional tube with a Robin type condition on its boundary and study, asymptotically, the spectrum of such operator as the diameter of the tube's cross section becomes infinitesimal. In contrast with the Dirichlet condition case [G. Bouchitté, M. L. Mascarenhas, and L. Trabucho, “On the curvature and torsion effects in one dimensional waveguides,” COCV 13(4), 793–808 (2007)10.1051/cocv:2007042], we evidence different behaviors depending on a symmetry criterium for the fundamental mode in the cross section. If that symmetry condition fails, then we prove the localization of lower energy levels in the vicinity of the minimum point of a suitable function on the tube's axis depending on the curvature and the rotation angle. In the symmetric case, the behavior of lower energy modes is shown to be ruled by a one-dimensional Sturm-Liouville problem involving an effective potential given in explicit form.
Lateral epitaxial overgrowth of nitrogen polar GaN on smooth nitrogen polar GaN templates by metalorganic chemical vapor deposition
Authors: Hussey Lindsay , Mita Seiji , Xie Jinqiao , Guo Wei , Akouala Christer-Rajiv , Rajan Joseph , Bryan Isaac , Collazo Ramón , Sitar Zlatko
Published: December 2012

Nitrogen (N)-polar GaN lateral epitaxial overgrowth (LEO), with a reduced dislocation density, is grown by metalorganic chemical vapor deposition on patterned, smooth N-polar templates. For LEO growth conditions identical to that of smooth N-polar GaN on sapphire, mask orientation dependent morphologies and faceting of the overgrowth regions are observed. N-polar LEO oriented along the 〈1-100〉 direction exhibit flat sidewall morphologies while LEO oriented along the 〈11-20〉 direction exhibit inclined sidewalls. A lateral to vertical growth ratio for the 〈1-100〉 and 〈11-20〉 oriented LEO was found to be ∼0.3 and 0.2, respectively. Transmission electron microscope observations reveal a reduction of dislocations of up to three orders of magnitude in the overgrowth regions from ∼1010 cm−2 in the template. Additionally, dislocation bending likely initiated from interfacial tension between the N-polar GaN and SiO2 mask is observed, resulting in a reduction of dislocation density to ∼109 cm−2 in the window region of re-growth.
Influence of the pattern shape on the efficiency of front-side periodically patterned ultrathin crystalline silicon solar cells
Authors: Herman Aline , Trompoukis Christos , Depauw Valérie , El Daif Ounsi , Deparis Olivier
Published: December 2012

Patterning the front side of an ultrathin crystalline silicon (c-Si) solar cell helps keeping the energy conversion efficiency high by compensating for the light absorption losses. A super-Gaussian mathematical expression was used in order to encompass a large variety of nanopattern shapes and to study their influence on the optical performance. We prove that the enhancement in the maximum achievable photo-current is due to both impedance matching condition at short wavelengths and to the wave nature of light at longer wavelengths. We show that the optimal mathematical shape and parameters of the pattern depend on the c-Si thickness. An optimal shape comes with a broad optimal parameter zone where experimental inaccuracies have much less influence on the efficiency. We prove that cylinders are not the best suited shape. To compare our model with a real slab, we fabricated a nanopatterned c-Si slab via nano imprint lithography.
Quantifying effects of hyperviscosity on isotropic turbulence
Authors: Spyksma Kyle , Magcalas Moriah , Campbell Natalie
Published: December 2012

Isotropic hyperviscous turbulence is modelled with a pseudospectral Navier-Stokes model and comparisons are made with regular-viscosity isotropic turbulence. Two proposed means of measuring the (hyperviscous) turbulent Reynolds number are presented and critiqued, leading to a proposal for a hyperviscous turbulent Reynolds number measured as a linear function of L/λ. An analysis of the statistics of velocity and velocity-derivative fields leads to comments on appropriate uses for hyperviscosity in theoretical and practical turbulence modelling and research.
Temperature dependence of Auger recombination in highly injected crystalline silicon
Authors: Wang Sisi , Macdonald Daniel
Published: December 2012

The Auger lifetime in crystalline silicon has been measured under high injection conditions using an injection- and temperature-dependent photoconductance apparatus, across a temperature range from 243 to 473 K (−30 to 200 °C). The corresponding ambipolar Auger coefficient was found to have a value of 1.6 × 10−30 cm6/s at 303 K (30 °C) at an injection level of 5 × 1016 cm−3. The Auger coefficient was found to decrease between 243 K and 303 K, and then remain approximately constant up to 473 K. An empirical parameterization of the measured ambipolar Auger coefficient is provided.
Solvatochromic shifts of polar and non-polar molecules in ambient and supercritical water: A sequential quantum mechanics/molecular mechanics study including solute-solvent electron exchange-correlation
Authors: Ma Haibo , Ma Yingjin
Published: December 2012

Polar and non-polar solutes (acetone and benzene) dissolved in ambient water and supercritical water are investigated theoretically using a sequential quantum mechanics (QM)/molecular mechanics (MM) method which combines classical molecular dynamics simulations and QM/MM calculations. From the detailed analysis of the dependence of the QM region size and point charge background region size as well as the different functionals, it is found that the inclusion of the solvent molecules within the first solvation shell into the QM region to account for the exchange-correlation between a solute and neighboring solvent molecules is important for the highly accurate spectral shift calculations, especially vital for the non-polar solutes whose interactions with the solvents are dominated by the quantum dispersions. At the same time, sufficiently large surrounding partial charge region (rcutoff ⩾15 Å) as well as the functional corrections to describe the long-range dispersion-corrections are also essential for the study of the electronic excited states in condensed phase. Our calculated solvatochromic shift values and their density dependencies at ambient and high temperature conditions are found to be in good agreements with experimental observations. This indicates that sound theoretical studies of solvatochromic shift can be achieved provided that a reasonable computational scheme with sufficiently large \documentclass[12pt]{minimal}\begin{document}$N^{QM}_{water}$\end{document}NwaterQM and rcutoff values is implemented. We also find both of aqueous acetone and aqueous benzene under high temperatures present three distinctive regions: low-density gas-like region, supercritical region, and high-density liquid-like region. The plateau behavior of solvatochromic shift in the supercritical region can be ascribed to the solvent clustering around the solute, which is a fundamental phenomenon of supercritical fluids (SCFs). The density dependence of our calculated coordination number of the first solvation shell nicely reproduces the trend of spectral shift and verifies the solvent clustering phenomenon of SCFs and its relationship with SCF’s physicochemical properties.
Does adsorption in a single nanogroove exhibit hysteresis?
Authors: Malijevský Alexandr
Published: December 2012

A simple fluid, in a microscopic capillary capped at one end, is studied by means of fundamental measure density functional. The model represents a single, infinitely long nanogroove with long-range wall-fluid attractive (dispersion) forces. It is shown that the presence or absence of hysteresis in adsorption isotherms is determined by wetting properties of the wall as follows: Above wetting temperature, Tw, appropriate to a single wall of the groove, the adsorption is a continuous process corresponding to a rise of a meniscus from the capped to the open end of the groove. For a sufficiently deep capillary, the meniscus rise is shown to be a steep, yet continuous process taking place near the capillary condensation of a corresponding slit. However, for temperatures lower than Tw the condensation exhibits a first-order transition accompanied by hysteresis of the adsorption isotherm. Finally, it is shown that hysteresis may occur even for T > Tw as a consequence of prewetting on the side and bottom walls of the groove.
Molecular mechanism of the adsorption process of an iodide anion into liquid-vapor interfaces of water-methanol mixtures
Authors: Annapureddy Harsha V. R. , Dang Liem X.
Published: December 2012

To enhance our understanding of the molecular mechanism of ion adsorption to the interface of mixtures, we systematically carried out a free energy calculations study involving the transport of an iodide anion across the interface of a water-methanol mixture. Many body affects are taken into account to describe the interactions among the species. The surface propensities of I− at interfaces of pure water and methanol are well understood. In contrast, detailed knowledge of the molecular level adsorption process of I− at aqueous mixture interfaces has not been reported. In this paper, we explore how this phenomenon will be affected for mixed solvents with varying compositions of water and methanol. Our potential of mean force study as function of varying compositions indicated that I− adsorption free energies decrease from pure water to pure methanol but not linearly with the concentration of methanol. We analyze the computed density profiles and hydration numbers as a function of concentrations and ion positions with respect to the interface to further explain the observed phenomenon.
Thermal conductivity of nano-grained SrTiO3 thin films
Authors: Foley Brian M. , Brown-Shaklee Harlan J. , Duda John C. , Cheaito Ramez , Gibbons Brady J. , Medlin Doug , Ihlefeld Jon F. , Hopkins Patrick E.
Published: December 2012

We measure the thermal conductivities of nano-grained strontium titanate (ng-SrTiO3) films deposited on sapphire substrates via time-domain thermoreflectance. The 170 nm thick oxide films of varying grain-size were prepared from a chemical solution deposition process. We find that the thermal conductivity of ng-SrTiO3 decreases with decreasing average grain size and attribute this to increased phonon scattering at grain boundaries. Our data are well described by a model that accounts for the spectral nature of anharmonic Umklapp scattering along with grain boundary scattering and scattering due to the film thickness.
Quantitative phase imaging of electron waves using selected-area diffraction
Authors: Yamasaki J. , Ohta K. , Morishita S. , Tanaka N.
Published: December 2012

A method for quantitative phase imaging of electron waves was developed based on diffractive imaging. Phase images over field of views of more than 100 nm were reconstructed from pairs of a selected-area diffraction pattern and a transmission electron microscopy image. The illumination wave field was reconstructed uniformly with a phase fluctuation of less than 0.1 rad and a spatial resolution of 2-3 nm. The phase image for wedge-shaped silicon was converted to a thickness map, which agreed quantitatively with electron energy-loss spectroscopy. The present method is also valid for arbitrary-shaped samples even if dynamical diffraction effects are significant.
Size-dependent efficiency and efficiency droop of blue InGaN micro-light emitting diodes
Authors: Tian Pengfei , McKendry Jonathan J. D. , Gong Zheng , Guilhabert Benoit , Watson Ian M. , Gu Erdan , Chen Zhizhong , Zhang Guoyi , Dawson Martin D.
Published: December 2012

The mechanisms of size-dependent efficiency and efficiency droop of blue InGaN micro-pixel light emitting diodes (μLEDs) have been investigated experimentally and by simulation. Electrical characterisation confirms the improvement of current spreading for smaller μLEDs, which enables the achievement of the higher efficiency at high injection current densities. Owing to the higher ratio of sidewall perimeter to mesa area of smaller μLEDs, a lower efficiency was observed at a low injection current density, resulting from defect-related Shockley-Read-Hall non-radiative recombination. We demonstrate that such sidewall etch defects can be partially recovered by increased thermal annealing time, consequently improving the efficiency at low current densities.
Polarization-diverse light absorption enhancement in organic photovoltaic structures with one-dimensional, long-pitch metallic gratings: Design and experiment
Authors: Liu Yifen , Dhakal Rabin , Dalal Vikram , Kim Jaeyoun
Published: December 2012

We report the design and experimental realization of an organic photovoltaic device structure that can trap incident light in all polarization states without relying on two-dimensional, short-pitch (<400 nm) gratings. Instead, we utilized easily patternable one-dimensional, long-pitch (>1000 nm) gratings and achieved the polarization diversity through balanced allocation of the plasmonic and guided mode-based light trapping routes to different polarization states. The experimental results showed strong enhancements in light absorption in all polarization states that would translate into a 15%–25% increase in the power conversion efficiency.
Unexpected effect of dye's molar extinction coefficient on performance of back contact dye-sensitized solar cells
Authors: Tjitra Salim Noviana , Zhang Kun , Zhang Shufang , Han Liyuan
Published: December 2012

The effect of dyes' molar extinction coefficients (ε) on the performance of back contact dye-sensitized cells (BCDSCs) was studied. Unexpected behavior, which contrasted with that expected for conventional DSCs, was observed. Specifically, a dye with lower ε improved the performance of BCDSCs, whereas a dye with higher ε did not improve the BCDSCs' efficiency, even with increasing TiO2 thickness. Our analysis revealed that BCDSCs with lower ε dye were capable to obtain a more efficient electron collection due to its higher electron generation rate closer to the collecting electrode and shorter electron transport distance, leading to an improved efficiency.
An improved magnetic field detection unit based on length-magnetized Terfenol-D and width-polarized ternary 0.35Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.30PbTiO3
Authors: Jiao Jie , Wang Wei , Li Lingying , Liu Yuting , Ren Bo , Deng Hao , Chen Jianwei , Xu Chundong , Di Wenning , Zhao Xiangyong , Luo Haosu , Jing Weiping
Published: December 2012

A magnetoelectric laminate composite based on length-magnetized Terfenol-D alloy and width-polarized ternary 0.35Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal has been developed and exhibits a giant magnetoelectric voltage coefficient of 1.7 V/Oe at low frequencies and 20 V/Oe at resonance frequency 84 020 Hz besides showing good linearity range of response in the field range of 1 pT-10 μT. Due to its small capacitance of 43 pF, a specially designed low-noise voltage follower was used to match the impedance. Based on the circuit, the detection limit of composite has been reached 1.9 pT/Hz1/2 at 1020 Hz and 300 fT/Hz1/2 at 84 020 Hz, respectively.
Traveling wave governs the stability of spatial pattern in a model of allelopathic competition interactions
Authors: Tian Canrong , Zhang Lai
Published: December 2012

Inhomogenous distribution of populations across physical space is a widely observed scenario in nature and has been studied extensively. Mechanisms accounting for these observations are such as diffusion-driven instability and mechanochemical approach. While conditions have been derived from a variety of models in biological, physical, and chemical systems to trigger the emergence of spatial patterns, it remains poorly understood whether the spatial pattern possesses asymptotical stability. In a plankton allelopathic competitive system with distributed time delay, we found that spatial pattern arises as a result of Hopf bifurcation and, in the meantime, there exists a unique asymptotically stable traveling wave solution. The convergence of the traveling wave solution to the emergent pattern and its stability infer that the emergent spatial pattern is locally asymptotically stable.
Synthesis of RAFT Block Copolymers in a Multi-Stage Continuous Flow Process Inside a Tubular Reactor
Authors: Hornung Christian H. , Nguyen Xuan , Kyi Stella , Chiefari John , Saubern Simon
Published: December 2012

This work describes a multi-stage continuous flow polymerisation process for the synthesis of block copolymers using the RAFT polymerization method. The process retains all the benefits and versatility of the RAFT method and has been adapted for a series of monomer combinations, including acrylates, acrylamides, and vinyl monomers. It resulted in polymers with molecular weights between 13500 and 34100 g mol–1, and dispersities typically between 1.21 and 1.58. Different architectures were prepared (including combinations of hydrophilic and hydrophobic blocks) which are soluble in a range of different solvents including aqueous and organic media.
An overview of the role of lucerne (Medicago sativa L.) in pastoral agriculture
Authors: Bouton J. H.
Published: December 2012

Pastoral agriculture is unique among the world’s agricultural production systems. Lucerne (also known as alfalfa), Medicago sativa L. subsp. sativa, has a long history of playing a very important role in pastoral agriculture. That role is expanding outside traditional hay and grazing production systems into sprouts for salads, nutritional supplements, and bioenergy feedstock. It is also the forage legume of choice for delivery of new traits via biotechnologies. The use of biotechnologies in lucerne improvement will cause re-examination of research methods and will require unique collaborations that are both interdisciplinary and even cross-institutional. The Consortium for Alfalfa Improvement (CAI) is discussed as a model for this type of collaboration. Breeding programs will continue development of cultivars with the proper fall (autumn) dormancy, a broad genetic base for pest resistance, increased local adaptation, persistence, and yield, while also adding new complex traits to these base traits. Increasing nutritional quality via down-regulation of lignin genes and increasing persistence via grazing tolerance, drought tolerance, and tolerance to acid, aluminium-toxic soils are discussed as examples of the potential impacts and challenges surrounding incorporation of complex traits. However, it is the potential for lucerne to become a major part of tropical or subtropical production systems or even an important adjunct to overcome deficiencies in the widely used perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) temperate systems that begs further attention.
Development of an early season barrel medic (Medicago truncatula Gaertn.) with tolerance to sulfonylurea herbicide residues
Authors: Peck D. M. , Howie J. H.
Published: December 2012

Sulfonylurea (SU) herbicides are extensively applied to crops in the cereal-livestock zones of southern Australia. In low rainfall areas with alkaline soils, SU residues can persist over summer and can severely affect sown or regenerating medic pastures. A cohort of early season barrel medics (Medicago truncatula) bred and selected for tolerance to SU herbicide residues were evaluated at multiple field sites over 3 years (year of establishment and subsequent regeneration). Two lines (Z2438 and Z2415) were identified which had dry matter production and seed yield in the establishment year equivalent to their recurrent parent, Caliph, an early maturing, aphid-tolerant, barrel medic cultivar. They also had lower levels of hardseededness than Caliph, enabling them to regenerate in greater numbers in the following year and thus produce more dry matter. The two lines demonstrated good tolerance to simulated SU herbicide residues, producing up to 10 times the dry matter of the SU-intolerant parent Caliph. We anticipate that one or both of the two lines will be commercialised soon, enabling farmers in low rainfall areas with neutral-to-alkaline soils to successfully grow barrel medic pastures in the presence of SU herbicide soil residues resulting from applications to prior crops.
Nutrient surpluses in Australian grazing systems: management practices, policy approaches, and difficult choices to improve water quality
Authors: Gourley C. J. P. , Weaver D. M.
Published: December 2012

Nutrient surpluses, inefficiencies in nutrient use, and inevitable leakage of nutrients from grazed animal production systems are putting growing pressure on Australian inland and coastal water resources. While there are some examples of regulatory policy approaches in Australia which aim to reduce nutrient emissions and improve water quality around important and impaired coastal and inland waters, most policy options involve voluntary schemes, often including financial incentives to both industry organisations and farmers to offset the costs of implementing improved management practices. In contrast, much stronger land management regulations have been implemented in the European Union, USA, and to a lesser extent New Zealand. In the near future, greater societal expectations for water quality, stricter standards from international markets, and increasing costs for purchased nutrients will mean that improving nutrient-use efficiency and reducing nutrient losses will be a necessary part of Australia livestock production systems. This is likely to require somewhat varied and difficult choices to better balance production and environmental goals. Policy responses may include voluntary adoption of appropriate nutrient management practices, caps on nutrient inputs, mandatory nutrient surplus targets, limits to stock numbers per hectare, and re-positioning of higher input farms to more resilient parts of the national landscape. Alternatively, society may have to accept that there are unavoidable trade-offs between water quality standards and livestock productivity, with increasing treatment of polluted water at the community’s expense.
Breeding and farming system opportunities for pasture legumes facing increasing climate variability in the south-west of Western Australia
Authors: Revell C. K. , Ewing M. A. , Nutt B. J.
Published: December 2012

The south-west of Western Australia has experienced a declining trend in annual rainfall and gradual warming over the last 30 years. The distribution of rainfall has also changed, with lower autumn rainfall, patchy breaks to the season, and shorter springs. This has important implications for the productivity of legume pastures in the region, which is dominated by annual species, particularly subterranean clover (Trifolium subterraneum L.), annual medics (Medicago spp.), serradella (Ornithopus spp.), and biserrula (Biserrula pelecinus L.). For annual pasture legumes, appropriate patterns of seed softening and germination behaviour, efficiency of phosphorus and potassium uptake, responses to elevated levels of atmospheric CO2, and drought resistance of seedlings and mature plants will assume increasing importance. While these traits can be targeted in pasture breeding programs, it will also be important to exploit farming system opportunities to optimise the annual legume component of the feed base. These opportunities may take the form of incorporating strategic shrub reserves and grazing crops to allow for pasture deferment in autumn–winter. Perennial forages may become more important in this context, as discussed in terms of the development of the perennial legume tedera (Bituminaria bituminosa var. albomarginata C.H. Stirton).
Nitrogen fixation in Australian dairy systems: review and prospect
Authors: Unkovich Murray
Published: December 2012

Quantitative measurement of N2 fixation has rarely been conducted in Australian dairy pastures. The available data indicate that annual N2 fixation rates in Australian dairy pastures are generally low, due to low pasture legume content. With typical legume contents of grazed pastures less than 30% of total pasture biomass production, annual N2 fixation in herbage is usually much less than 50 kg ha–1 year–1. Other factors which are likely to be able to contribute to increased N2 fixation input (rhizobia, mineral N management, soil acidity, soil water contents) will have little impact until such time as legume contents are increased. In contrast, for some hay systems, such as those using lucerne, N2 fixation input is shown to be high (200–300 kg ha–1 year–1). While pasture clover contents remain low there is little value in study or measurement of N2 fixation, nor in complex modelling, as N2 fixation will be of little quantitative importance. However, where legume contents, and thus potential N2 fixation are increased, there is scope for investigation into potential increases in N input from this source, which is invariably linked to fertiliser application, the management of grazing and the N returns in urine and dung. These are the major influences on sward N dynamics and legume N2 fixation. The inoculant rhizobia used for white clover in Australia (TA1) is likely to be suboptimal. Isolated in Tasmania in 1953 it has been shown to be inferior in N2 fixation compared with other strains on several occasions. Root pests and diseases are likely to be prevalent and impact directly on clover root growth and perhaps nodulation. Modelling is often used to describe the probable influence of management and/or climate on the operation of agricultural systems. Reliable modelling of N2 fixation requires capacity to integrate the effects of grazing and pasture composition on soil mineral N dynamics, the influence of this mineral N on nodulation and on suppression of N2 fixation, and environmental and management influences on soil rhizobial populations. Currently no models have demonstrated this capacity. At present, a suitably calibrated regression model is probably a good option for modelling N2 fixation in Australian dairy pastures. Environmental benefits ensuing from increasing N2 fixation and substituting this for fertiliser N are likely to be greater off-farm (reduced GHG emissions at site of fertiliser manufacture) than on, if current fertiliser management is optimal. Nevertheless substituting fixed N for fertiliser N would have modest environmental and feed efficiency benefits.
Competitive ligand exchange reveals time dependant changes in the reactivity of Hg–dissolved organic matter complexes
Authors: Miller Carrie L. , Liang Liyuan , Gu Baohua
Published: December 2012

Environmental contextMercury, a globally important pollutant, undergoes transformations in the environment to form methylmercury that is toxic to humans. Naturally occurring dissolved organic matter is a controller in these transformations, and we demonstrate that its strength of interaction with mercury is time dependent. These changes in complexation with dissolved organic matter are likely to affect mercury’s reactivity in aquatic systems, thereby influencing how mercury is methylated and bioaccumulated.
AbstractMercury interactions with dissolved organic matter (DOM) are important in aquatic environments but the kinetics of Hg binding to and repartitioning within the DOM remain poorly understood. We examined changes in Hg–DOM complexes using glutathione (GSH) titrations, coupled with stannous-reducible Hg measurements during Hg equilibration with DOM. In laboratory prepared DOM solutions and in water from a Hg-contaminated creek, a fraction of the Hg present as Hg–DOM complexes did not react to GSH addition. This unreactive Hg fraction increased with time from 13 % at 1 h to 74 % after 48 h of equilibration with a Suwannee River DOM. In East Fork Poplar Creek water in Oak Ridge, Tennessee, ~58 % of the DOM-complexed Hg was unreactive with GSH 1 h after the sample was collected. This time-dependent increase in unreactive Hg suggests that Hg forms stronger complexes with DOM over time. Alternatively the DOM-complexed Hg may become more sterically protected from the ligand exchange reactions, as the binding environment changes within the DOM over time. These results have important implications to understanding Hg transformations in the natural environment, particularly in contaminated aquatic systems due to non-equilibrium interactions between Hg and DOM.
Successful cloning of coyotes through interspecies somatic cell nuclear transfer using domestic dog oocytes
Authors: Hwang Insung , Jeong Yeon Woo , Kim Joung Joo , Lee Hyo Jeong , Kang Mina , Park Kang Bae , Park Jung Hwan , Kim Yeun Wook , Kim Woo Tae , Shin Taeyoung , Hyun Sang Hwan , Jeung Eui-Bae , Hwang Woo Suk
Published: December 2012

Interspecies somatic cell nuclear transfer (iSCNT) is an emerging assisted reproductive technology (ART) for preserving Nature’s diversity. The scarcity of oocytes from some species makes utilisation of readily available oocytes inevitable. In the present study, we describe the successful cloning of coyotes (Canis latrans) through iSCNT using oocytes from domestic dogs (Canis lupus familiaris or dingo). Transfer of 320 interspecies-reconstructed embryos into 22 domestic dog recipients resulted in six pregnancies, from which eight viable offspring were delivered. Fusion rate and cloning efficiency during iSCNT cloning of coyotes were not significantly different from those observed during intraspecies cloning of domestic dogs. Using neonatal fibroblasts as donor cells significantly improved the cloning efficiency compared with cloning using adult fibroblast donor cells (P < 0.05). The use of domestic dog oocytes in the cloning of coyotes in the present study holds promise for cloning other endangered species in the Canidae family using similar techniques. However, there are still limitations of the iSCNT technology, as demonstrated by births of morphologically abnormal coyotes and the clones’ inheritance of maternal domestic dog mitochondrial DNA.
Soybean sudden death syndrome - advances in knowledge and disease management.
Authors: Leandro L. F. , Tatalovic N. , Luckew A.
Published: December 2012

Sudden death syndrome (SDS) of soybean is a concern in the major soybean producing regions of North and South America. The disease is caused by soil-borne fungi of the genus
Fusarium
and is most recognized by the development of interveinal chlorosis and necrosis on leaves, and premature defoliation. Yield losses associated with SDS can be economically devastating depending on disease intensity and timing of disease onset. Our understanding about SDS has greatly expanded since it was first described in the USA in 1971, and a comprehensive review of the disease was written in 1997 by Roy
et al
. The goal of the present review is to provide an update on the current knowledge on SDS and identify resources where more detailed information can be found. The review will cover information on disease distribution and impact, pathogen taxonomy, disease aetiology, interactions with biotic and abiotic factors and disease management.
Planning a competence‐based curriculum: the case of four secondary schools in England
Authors: Byrne Jenny , Downey Christopher , Souza Ana
Published: December 2012

Despite the belief that schools tend to be resistant to change, it is possible to find secondary schools in the UK which are investing in the design of an innovative curriculum for their Year 7 (11‐year‐old students). This article focuses on four of these schools and discusses some of the challenges they face in planning and implementing their competence‐based curricula (CBC). Such curricula tend to be based on the rationale that they better prepare all students for the constant changes of human knowledge and understanding. They develop transferable skills rather than subject‐specific content, which are considered necessary requirements for learners as future productive members of society in the twenty‐first century. Advocates of CBC argue that such curricula are more inclusive and emancipatory than traditional curricula, although this view is contested. Employing Bernstein%s concepts of framing and classification of the curriculum, this article describes the challenges and constraints encountered by four schools which have endeavoured to develop a competence‐based curriculum.
Performing post-migration cinema in Italy:Corazones de Mujerby K. Kosoof
Authors: Mazzara Federica
Published: December 2012

Following consideration of the most common representations of migrants in Italian cinema, where they are often portrayed as victimised and minor subjects, this article analyses a film by Davide Sordella and Pablo Benedetti,Corazones de Mujer(2008) as a ‘post-migration alternative’. This film considers a different way of depicting ‘foreigners’, and addresses the complex issues of gender and sexuality as they emerge at the interface between Western and Arab cultures. Within the conceptual framework of Judith Butler's ‘gender performativity’ and Rosi Braidotti's ‘nomadic subject’, this article aims to suggest an alternative way of representing migrants in Italian cinema as agents of social and gender transgressions.
Working with Psychopathic Offenders: Lessons from the Chromis Program
Authors: Atkinson Rachel , Tew Jenny
Published: December 2012

Psychopathic traits impact on an individual's engagement with treatment and on the staff who deliver that treatment. This article shares what has been learned about developing and implementing a treatment program for this group, particularly in relation to staff selection and support. The Chromis program aims to reduce violence in men with high levels of psychopathic traits. In the light of what is known about psychopathic offenders in treatment and their impact on staff this paper outlines the development of a competency framework, recruitment process and training and support program for staff involved in Chromis. It also considers the evaluation of this process with a view to assisting others.
Population Genetic Comparisons among Cobia from the Northern Gulf of Mexico, U.S. Western Atlantic, and Southeast Asia
Authors: Gold John R , Giresi Melissa M , Renshaw Mark A , Gwo Jin-Chywan
Published: December 2012

Nuclear-encoded microsatellites and mitochondrial DNA (mtDNA) sequences were assayed from Cobias Rachycentron canadum sampled in waters offshore of Virginia (U.S. Atlantic), Mississippi and Louisiana (Gulf of Mexico), and Taiwan (Southeast Asia). Global exact tests and analysis of molecular variance revealed that Cobias from U.S. waters were homogeneous for alleles and genotype distributions at 27 nuclear-encoded microsatellites and were homogeneous in mtDNA haplotype distribution, whereas both genetic markers in Cobias from Taiwan differed significantly from those of Cobias in U.S. waters. Based on these genetic differences, use of Cobia broodstock from Southeast Asia in U.S. aquaculture facilities is not recommended. Results are compatible with the use of Cobia broodstock from either the U.S. Atlantic or the Gulf of Mexico for aquaculture at U.S. facilities; caveats to the exchange of broodstock between these two regions are discussed.
Women and Catholic Manuscript Networks in Seventeenth-Century England: New Research on Constance Aston Fowler’s Miscellany of Sacred and Secular Verse*
Authors: Hackett Helen
Published: December 2012

Huntington Library manuscript HM904 is a verse miscellany compiled by Constance Aston Fowler, daughter of Lord Aston, in 1630s Staffordshire. Constance operated as a kind of literary agent, soliciting, exchanging, and circulating poems, as well as preserving them in her book. Many of these poems are by or about family and friends, but they also indicate her connections with far-reaching networks of manuscript transmission. In particular, the volume contains Catholic devotional verses in an unusual and somewhat archaic hand (Hand B) that also appears in another Catholic miscellany from 1650s Warwickshire; and secular verses that may be by the Catholic love poet William Habington, or may be hybrid compositions that imitate or adapt his work. Both these ingredients have much to say about the complex compilation processes of manuscript verse miscellanies, and about the cultural participation of women and Catholics in seventeenth-century England.
Enhanced photocatalytic performance: a β-Bi2O3 thin film by nanoporous surface
Authors: Yang Xin , Lian Xiaojuan , Liu Shangjun , Wang Gang , Jiang Chunping , Tian Jing , Chen Jinwei , Wang Ruilin
Published: December 2012

Beta-Bi2O3 film photoanodes with different surface structures were prepared by oxidizing bismuth films. The physical properties were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible absorbance spectra and atomic force microscopy (AFM). XRD shows that all films are beta phase crystal structure except the thinnest 12 nm film. SEM and AFM characterizations indicate that a nanoporous surface structure is generated on the surface after the film is annealed for 3 h, while the films annealed for 1 h show a dense surface. The direct band gaps vary from 2.63 to 2.88 eV, with the film thickness decreasing from 500 to 12 nm. The nanoporous surface structure film exhibits better light harvesting ability and incident photon-to-electron conversion efficiency (IPCE) than the dense surface films. The IPCE (61% at 350 nm and 43% at 400 nm, 0.197 VNHE) is the highest ever reported. The photocurrent density reaches 0.45 mA cm−2 when illuminated with a bias of 1.23 VNHE in 0.5M Na2SO3.
UV-laser treatment of nanodiamond seeds—a valuable tool for modification of nanocrystalline diamond films properties
Authors: Vlček J , Fitl P , Vrňata M , Fekete L , Taylor A , Fendrych F
Published: December 2012

This work aimed to study the UV-laser treatment of precursor (i.e. nanodiamond (ND) seeds on silicon substrates) and its influence on the properties of grown nanocrystalline diamond (NCD) films. Pulsed Nd : YAG laser operating at the fourth harmonic frequency (laser fluence E
L = 250 mJ cm−2, pulse duration 5 ns) was used as a source, equipped with an optical system for focusing laser beam onto the sample, allowing exposure of a local spot and horizontal patterning. The variable parameters were: number of pulses (from 5 to 400) and the working atmosphere (He, Ar and O2). Ablation and/or graphitization of seeded nanodiamond particles were observed. Further the microwave plasma-enhanced chemical vapour deposition was employed to grow NCD films on exposed and non-exposed areas of silicon substrates. The size, shape and density distribution of laser-treated nanodiamond seeds were observed by atomic force microscopy (AFM) and their chemical composition by x-ray photoelectron spectroscopy (XPS) analysis. The resulting NCD films (uniform thickness of 400 nm) were characterized by: Raman spectroscopy to analyse occurrence of graphitic phase, and AFM to observe morphology and surface roughness. The highest RMS roughness (∼85 nm) was achieved when treating the precursor in He atmosphere. Horizontal microstructures of diamond films were fabricated.
Providing Numbers for a Food versus Fuel Debate: An Analysis of a Future Biofuel Production Scenario
Authors: Poudel Biswo N. , Paudel Krishna P. , Timilsina Govinda , Zilberman David
Published: December 2012

This study provides a quantitative estimate of grain that would be available for biofuel production under different scenarios of dietary requirements in the world in 2050 based on the projected information available in 2007 on population, productivity increase, dietary requirements, and land use types. Our major findings are as follows: (1) if dietary requirements do not increase by more than 20% from the current level, crop yields from current cropland must increase by more than 57% just to meet dietary demand; (2) the restriction of pastureland for milk and meat production purposes would imply insufficient food production for a moderate diet consumption scenario in 2050; (3) If food demand increases by 20% of the current consumption level, a 60% increase in crop yield and a 16% conversion of pasturelands would meet grain demand and leave surplus grain to supply 23% of liquid fuel demand. We also highlight the potential roles played by biotechnology, research and development fundings, irrigation, and cropping intensity to boost crop production and ultimately make more land available for biofuel production if such an option continues to be considered in future.
A further study on seismic response of a set of parallel rock fractures filled with viscoelastic materials
Authors: Wu W. , Zhu J. B. , Zhao J.
Published: December 2012

The purpose of this study is to further investigate the seismic response of a set of parallel rock fractures filled with viscoelastic materials, following the work by Zhu et al. Dry quartz sands are used to represent the viscoelastic materials. The split Hopkinson rock bar (SHRB) technique is modified to simulate 1-D P-wave propagation across the sand-filled parallel fractures. At first, the displacement and stress discontinuity model (DSDM) describes the seismic response of a sand-filled single fracture. The modified recursive method (MRM) then predicts the seismic response of the sand-filled parallel fractures. The SHRB tests verify the theoretical predictions by DSDM for the sand-filled single fracture and by MRM for the sand-filled parallel fractures. The filling sands cause stress discontinuity across the fractures and promote displacement discontinuity. The wave transmission coefficient for the sand-filled parallel fractures depends on wave superposition between the fractures, which is similar to the effect of fracture spacing on the wave transmission coefficient for the non-filled parallel fractures.
Population Genetic Structure of Phytophthora cinnamomi Associated with Avocado in California and the Discovery of a Potentially Recent Introduction of a New Clonal Lineage
Authors: Pagliaccia D. , Pond E. , McKee B. , Douhan G. W.
Published: December 2012

Phytophthora root rot (PRR) of avocado (Persea americana), caused by Phytophthora cinnamomi, is the most serious disease of avocado worldwide. Previous studies have determined that this pathogen exhibits a primarily clonal reproductive mode but no population level studies have been conducted in the avocado-growing regions of California. Therefore, we used amplified fragment length polymorphism based on 22 polymorphic loci and mating type to investigate pathogen diversity from 138 isolates collected in 2009 to 2010 from 15 groves from the Northern and Southern avocado-growing regions. Additional isolates collected from avocado from 1966 to 2007 as well as isolates from other countries and hosts were also used for comparative purposes. Two distinct clades of A2 mating-type isolates from avocado were found based on neighbor joining analysis; one clade contained both newer and older collections from Northern and Southern California, whereas the other clade only contained isolates collected in 2009 and 2010 from Southern California. A third clade was also found that only contained A1 isolates from various hosts. Within the California population, a total of 16 genotypes were found with only one to four genotypes identified from any one location. The results indicate significant population structure in the California avocado P. cinnamomi population, low genotypic diversity consistent with asexual reproduction, potential evidence for the movement of clonal genotypes between the two growing regions, and a potential introduction of a new clonal lineage into Southern California.
Fungal Mitochondrial DNases: Effectors with the Potential to Activate Plant Defenses in Nonhost Resistance
Authors: Hadwiger Lee A. , Polashock James
Published: December 2012

Previous reports on the model nonhost resistance interaction between Fusarium solani f. sp. phaseoli and pea endocarp tissue have described the disease resistance-signaling role of a fungal DNase1-like protein. The response resulted in no further growth beyond spore germination. This F. solani f. sp. phaseoli DNase gene, constructed with a pathogenesis-related (PR) gene promoter, when transferred to tobacco, generated resistance against Pseudomonas syringe pv. tabaci. The current analytical/theoretical article proposes similar roles for the additional nuclear and mitochondrial nucleases, the coding regions for which are identified in newly available fungal genome sequences. The amino acid sequence homologies within functional domains are conserved within a wide array of fungi. The potato pathogen Verticillium dahliae nuclease was divergent from that of the saprophyte, yeast; however, the purified DNase from yeast also elicited nonhost defense responses in pea, including pisatin accumulation, PR gene induction, and resistance against a true pea pathogen. The yeast mitochondrial DNase gene (open reading frame) predictably codes for a signal peptide providing the mechanism for secretion. Mitochondrial DNase genes appear to provide an unlimited source of components for developing transgenic resistance in all transformable plants.
MULTIFOCAL RETINAL ASTROCYTIC HAMARTOMAS
Authors: Bui Kelly M. , Leiderman Yannek I. , Lim Jennifer I. , Mieler William F.
Published: December 2012

Purpose:

Retinal astrocytic hamartoma is a benign glial tumor found in the nerve fiber layer, and it is most commonly reported as a solitary lesion. Multiple or bilateral lesions may be indicative of systemic disease, such as tuberous sclerosis complex or neurofibromatosis 1. We present three unique cases of multifocal and bilateral retinal astrocytic hamartomas in patients with suspected tuberous sclerosis complex. The typical features, diagnosis, management, and systemic implications of these retinal lesions are discussed.

Methods:

Consecutive case series at a university-based ophthalmology clinic.

Results:

The age of the patients ranged from 9 years to 27 years. The patients came from different ethnic backgrounds and had no known family history of tuberous sclerosis complex or neurofibromatosis. Two of the three patients had asthma, along with brain and kidney tumors. Two of the three patients had a seizure disorder, and one of the three patients had mental retardation. Only one patient presented with an ocular complaint of decreased vision, as a result of a presumed unrelated process. All patients had bilateral and multifocal astrocytic hamartomas.

Conclusion:

Multifocal retinal astrocytic hamartomas are unique and can be the first manifestation of a systemic disease such as tuberous sclerosis complex or neurofibromatosis 1. Prompt referral for imaging and workup with the appropriate medical subspecialty can help prevent or delay the morbidity related to these systemic conditions.