bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical modeling and experimental observations of the atomic layer deposition of SrO using a cyclopentadienyl Sr precursor
Authors: Fredrickson Kurt D. , McDaniel Martin D. , Slepko Alex , Ekerdt John G. , Demkov Alexander A.
Published: August 2016

First-principle calculations are used to model the adsorption and hydration of strontium bis(cyclopentadienyl) [Sr(Cp)2] on TiO2-terminated strontium titanate, SrTiO3 (STO), for the deposition of strontium oxide, SrO, by atomic layer deposition (ALD). The Sr(Cp)2 precursor is shown to adsorb on the TiO2-terminated surface, with the Sr atom assuming essentially the bulk position in STO. The C–Sr bonds are weaker than in the free molecule, with a Ti atom at the surface bonding to one of the C atoms in the cyclopentadienyl rings. The surface does not need to be hydrogenated for precursor adsorption. The calculations are compared with experimental observations for a related Sr cyclopentadienyl precursor, strontium bis(triisopropylcyclopentadienyl) [Sr(iPr3Cp)2], adsorbed on TiO2-terminated STO. High-resolution x-ray photoelectron spectroscopy and low-energy ion scattering spectroscopy show adsorption of the Sr precursor on the TiO2-terminated STO after a single precursor dose. This study suggests that ALD growth from the strontium precursors featuring cyclopentadienyl ligands, such as Sr(Cp)2, may initiate film growth on non-hydroxylated surfaces.
Density scaling and decoupling in o-terphenyl, salol, and dibutyphthalate
Authors: Casalini R. , Bair S. S. , Roland C. M.
Published: August 2016

We present new viscosity and equation of state (EoS) results extending to high pressures for o-terphenyl, salol, and dibutylphthalate. Using these and data from the literature, we show that the three liquids all conform to density scaling; that is, their reduced viscosities and reorientational relaxation times are a function of the ratio of temperature and density with the latter raised to a constant. Moreover, the functional form of the dependence on this ratio is independent of the experimental probe of the dynamics. This means that there is no decoupling of the viscosities and relaxation times over the measured range of conditions. Previous literature at odds with these results was based on erroneous extrapolations of the EoS or problematic diamond anvil viscosity data. Thus, there are no exceptions to the experimental fact that every non-associated liquid complies with density scaling with an invariant scaling exponent.
On the channel width-dependence of the thermal conductivity in ultra-narrow graphene nanoribbons
Authors: Karamitaheri Hossein , Neophytou Neophytos
Published: August 2016

The thermal conductivity of low-dimensional materials and graphene nanoribbons, in particular, is limited by the strength of line-edge-roughness scattering. One way to characterize the roughness strength is the dependency of the thermal conductivity on the channel's width in the form Wβ. Although in the case of electronic transport, this dependency is very well studied, resulting in W6 for nanowires and quantum wells and W4 for nanoribbons, in the case of phonon transport it is not yet clear what this dependence is. In this work, using lattice dynamics and Non-Equilibrium Green's Function simulations, we examine the width dependence of the thermal conductivity of ultra-narrow graphene nanoribbons under the influence of line edge-roughness. We show that the exponent β is in fact not a single well-defined number, but it is different for different parts of the phonon spectrum depending on whether phonon transport is ballistic, diffusive, or localized. The exponent β takes values β < 1 for semi-ballistic phonon transport, values β ≫ 1 for sub-diffusive or localized phonons, and β = 1 only in the case where the transport is diffusive. The overall Wβ dependence of the thermal conductivity is determined by the width-dependence of the dominant phonon modes (usually the acoustic ones). We show that due to the long phonon mean-free-paths, the width-dependence of thermal conductivity becomes a channel length dependent property, because the channel length determines whether transport is ballistic, diffusive, or localized.
On exact traveling-wave solutions for local fractional Korteweg-de Vries equation
Authors: Yang Xiao-Jun , Tenreiro Machado J. A. , Baleanu Dumitru , Cattani Carlo
Published: August 2016

This paper investigates the Korteweg-de Vries equation within the scope of the local fractional derivative formulation. The exact traveling wave solutions of non-differentiable type with the generalized functions defined on Cantor sets are analyzed. The results for the non-differentiable solutions when fractal dimension is 1 are also discussed. It is shown that the exact solutions for the local fractional Korteweg-de Vries equation characterize the fractal wave on shallow water surfaces.
Network-complement transitions, symmetries, and cluster synchronization
Authors: Nishikawa Takashi , Motter Adilson E.
Published: August 2016

Synchronization in networks of coupled oscillators is known to be largely determined by the spectral and symmetry properties of the interaction network. Here, we leverage this relation to study a class of networks for which the threshold coupling strength for global synchronization is the lowest among all networks with the same number of nodes and links. These networks, defined as being uniform, complete, and multi-partite (UCM), appear at each of an infinite sequence of network-complement transitions in a larger class of networks characterized by having near-optimal thresholds for global synchronization. We show that the distinct symmetry structure of the UCM networks, which by design are optimized for global synchronizability, often leads to formation of clusters of synchronous oscillators, and that such states can coexist with the state of global synchronization.
Comparison of the growth kinetics of In2O3 and Ga2O3 and their suboxide desorption during plasma-assisted molecular beam epitaxy
Authors: Vogt Patrick , Bierwagen Oliver
Published: August 2016

We present a comprehensive study of the In2O3 growth kinetics during plasma-assisted molecular beam epitaxy and compare it to that of the related oxide Ga2O3 [P. Vogt and O. Bierwagen, Appl. Phys. Lett. 108, 072101 (2016)]. The growth rate and desorbing fluxes were measured during growth in-situ by a laser reflectometry set-up and line-of-sight quadrupole mass spectrometer, respectively. We extracted the In incorporation as a function of the provided In flux, different growth temperatures TG, and In-to-O flux ratios r. The data are discussed in terms of the competing formation of In2O3 and desorption of the suboxide In2O and O. The same three growth regimes as in the case of Ga2O3 can be distinguished: (i) In-transport limited, O-rich (ii) In2O-desorption limited, O-rich, and (iii) O-transport limited, In-rich. In regime (iii), In droplets are formed on the growth surface at low TG. The growth kinetics follows qualitatively that of Ga2O3 in agreement with their common oxide and suboxide stoichiometry. The quantitative differences are mainly rationalized by the difference in In2O and Ga2O desorption rates and vapor pressures. For the In2O, Ga2O, and O desorption, we extracted the activation energies and frequency factors by means of Arrhenius-plots.
Reduction of thermal conductivity in MnSi1.7 multi-layered thin films with artificially inserted Si interfaces
Authors: Kurosaki Y. , Yabuuchi S. , Nishide A. , Fukatani N. , Hayakawa J.
Published: August 2016

We report a lowered lattice thermal conductivity in nm-scale MnSi1.7/Si multilayers which were fabricated by controlling thermal diffusions of Mn and Si atoms. The thickness of the constituent layers is 1.5–5.0 nm, which is comparable to the phonon mean free path of both MnSi1.7 and Si. By applying the above nanostructures, we reduced the lattice thermal conductivity down to half that of bulk MnSi1.7/Si composite materials. The obtained value of 1.0 W/K m is the experimentally observed minimum in MnSi1.7-based materials without any heavy element doping and close to the minimum thermal conductivity. We attribute the reduced lattice thermal conductivity to phonon scattering at the MnSi1.7/Si interfaces in the multilayers.
Charge transport model in nanodielectric composites based on quantum tunneling mechanism and dual-level traps
Authors: Li Guochang , Chen George , Li Shengtao
Published: August 2016

Charge transport properties in nanodielectrics present different tendencies for different loading concentrations. The exact mechanisms that are responsible for charge transport in nanodielectrics are not detailed, especially for high loading concentration. A charge transport model in nanodielectrics has been proposed based on quantum tunneling mechanism and dual-level traps. In the model, the thermally assisted hopping (TAH) process for the shallow traps and the tunnelling process for the deep traps are considered. For different loading concentrations, the dominant charge transport mechanisms are different. The quantum tunneling mechanism plays a major role in determining the charge conduction in nanodielectrics with high loading concentrations. While for low loading concentrations, the thermal hopping mechanism will dominate the charge conduction process. The model can explain the observed conductivity property in nanodielectrics with different loading concentrations.
Characterization of encapsulated quantum dots via electron channeling contrast imaging
Authors: Deitz Julia I. , Carnevale Santino D. , De Graef Marc , McComb David W. , Grassman Tyler J.
Published: August 2016

A method for characterization of encapsulated epitaxial quantum dots (QD) in plan-view geometry using electron channeling contrast imaging (ECCI) is presented. The efficacy of the method, which requires minimal sample preparation, is demonstrated with proof-of-concept data from encapsulated (sub-surface) epitaxial InAs QDs within a GaAs matrix. Imaging of the QDs under multiple diffraction conditions is presented, establishing that ECCI can provide effectively identical visualization capabilities as conventional two-beam transmission electron microscopy. This method facilitates rapid, non-destructive characterization of sub-surface QDs giving immediate access to valuable nanostructural information.
Spatiotemporal dynamics of Gaussian laser pulse in a multi ions plasma
Authors: Jafari Milani M. R.
Published: August 2016

Spatiotemporal evolutions of Gaussian laser pulse propagating through a plasma with multiple charged ions are studied, taking into account the ponderomotive nonlinearity. Coupled differential equations for beam width and pulse length parameters are established and numerically solved using paraxial ray approximation. In one-dimensional geometry, effects of laser and plasma parameters such as laser intensity, plasma density, and temperature on the longitudinal pulse compression and the laser intensity distribution are analyzed for plasmas with singly and doubly charged ions. The results demonstrate that self-compression occurs in a laser intensity range with a turning point intensity in which the self-compression process has its strongest extent. The results also show that the multiply ionized ions have different effect on the pulse compression above and below turning point intensity. Finally, three-dimensional geometry is used to analyze the simultaneous evolution of both self-focusing and self-compression of Gaussian laser pulse in such plasmas.
Study of plasma equilibrium in toroidal fusion devices using mesh-free numerical calculation method
Authors: Rasouli C. , Abbasi Davani F. , Rokrok B.
Published: August 2016

Plasma confinement using external magnetic field is one of the successful ways leading to the controlled nuclear fusion. Development and validation of the solution process for plasma equilibrium in the experimental toroidal fusion devices is the main subject of this work. Solution of the nonlinear 2D stationary problem as posed by the Grad-Shafranov equation gives quantitative information about plasma equilibrium inside the vacuum chamber of hot fusion devices. This study suggests solving plasma equilibrium equation which is essential in toroidal nuclear fusion devices, using a mesh-free method in a condition that the plasma boundary is unknown. The Grad-Shafranov equation has been solved numerically by the point interpolation collocation mesh-free method. Important features of this approach include truly mesh free, simple mathematical relationships between points and acceptable precision in comparison with the parametric results. The calculation process has been done by using the regular and irregular nodal distribution and support domains with different points. The relative error between numerical and analytical solution is discussed for several test examples such as small size Damavand tokamak, ITER-like equilibrium, NSTX-like equilibrium, and typical Spheromak.
Electric transport coefficients in highly epitaxial LaBaCo2O5 + δ films with “p-to-n” transition induced by oxygen deficiency
Authors: Shaibo J. , Zhang Q. Y. , Wang Y. Q. , Hu H. C. , Li X. N. , Pan L. J.
Published: August 2016

Electric transport coefficients such as carrier type, density, and mobility are the important physical parameters in designing functional devices. In this work, we report the study on the electric transport coefficients of the highly epitaxial LaBaCo2O5 + δ (LBCO) films, which were discussed as a function of electric conductivity for the first time and compared with the results calculated by the theory for mixed conduction. The mobility in the LBCO films was determined to be ∼0.85 and ∼40 cm2/V s for holes and electrons, respectively, and the density of p-type carriers strongly depends on the oxygen deficiency. Solid evidence is presented to demonstrate that the oxygen deficiency cannot make LBCO materials changed from p- to n-type. The n-type conduction observed in experiment is a counterfeit phenomenon caused by the deficiency in Hall measurement, rather than a realistic transition induced by oxygen deficiency. In addition, the temperature-dependent conductivity was discussed using the differential coefficients, which might be useful in the study of the samples with magnetic transition.
Chemical trends of Schottky barrier behavior on monolayer hexagonal B, Al, and Ga nitrides
Authors: Lu Haichang , Guo Yuzheng , Robertson John
Published: August 2016

The Schottky Barrier Heights (SBH) of metal layers on top of monolayer hexagonal X-nitrides (X = B, Al, Ga, and h-XN) are calculated using supercells and density functional theory so as to understand the chemical trends of contact formation on graphene and the 2D layered semiconductors such as the transition metal dichalcogenides. The Fermi level pinning factor S of SBHs on h-BN is calculated to be nearly 1, indicating no pinning. For h-AlN and h-GaN, the calculated pinning factor is about 0.63, less than for h-BN. We attribute this to the formation of stronger, chemisorptive bonds between the nitrides and the contact metal layer. Generally, the h-BN layer remains in a planar sp2 geometry and has weak physisorptive bonds to the metals, whereas h-AlN and h-GaN buckle out of their planar geometry which enables them to form the chemisorptive bonds to the metals.
On twin density and resistivity of nanometric Cu thin films
Authors: Barmak Katayun , Liu Xuan , Darbal Amith , Nuhfer N. Thomas , Choi Dooho , Sun Tik , Warren Andrew P. , Coffey Kevin R. , Toney Michael F.
Published: August 2016

Crystal orientation mapping in the transmission electron microscope was used to quantify the twin boundary length fraction per unit area for five Ta38Si14N48/SiO2 encapsulated Cu films with thicknesses in the range of 26–111 nm. The length fraction was found to be higher for a given twin-excluded grain size for these films compared with previously investigated SiO2 and Ta/SiO2 encapsulated films. The quantification of the twin length fraction per unit area allowed the contribution of the twin boundaries to the size effect resistivity to be assessed. It is shown that the increased resistivity of the Ta38Si14N48 encapsulated Cu films compared with the SiO2 and Ta/SiO2 encapsulated films is not a result of increased surface scattering, but it is a result of the increase in the density of twin boundaries. With twin boundaries included in the determination of grain size as a mean-intercept length, the resistivity data are well described by 2-parameter Matthiessen's rule summation of the Fuchs-Sondheimer and Mayadas Shatzkes models, with p and R parameters that are within experimental error equal to those in prior reports and are p = 0.48(+0.33/−0.31) and R = 0.27 ± 0.03.
Double-gated Si NW FET sensors: Low-frequency noise and photoelectric properties
Authors: Gasparyan F. , Khondkaryan H. , Arakelyan A. , Zadorozhnyi I. , Pud S. , Vitusevich S.
Published: August 2016

The transport, noise, and photosensitivity properties of an array of silicon nanowire (NW) p+-p-p+ field-effect transistors (FETs) are investigated. The peculiarities of photosensitivity and detectivity are analyzed over a wide spectrum range. The absorbance of p-Si NW shifts to the short wavelength region compared with bulk Si. The photocurrent and photosensitivity reach increased values in the UV range of the spectrum at 300 K. It is shown that sensitivity values can be tuned by the drain-source voltage and may reach record values of up to 2–4 A/W at a wavelength of 300 nm at room temperature. Low-frequency noise studies allow calculating the photodetectivity values, which increase with decreasing wavelength down to 300 nm. We show that the drain current of Si NW biochemical sensors substantially depends on pH value and the signal-to-noise ratio reaches the high value of 105. Increasing pH sensitivity with gate voltage is revealed for certain source-drain currents of pH-sensors based on Si NW FETs. The noise characteristic index decreases from 1.1 to 0.7 with the growth of the liquid gate voltage. Noise behavior is successfully explained in the framework of the correlated number-mobility unified fluctuation model. pH sensitivity increases as a result of the increase in liquid gate voltage, thus giving the opportunity to measure very low proton concentrations in the electrolyte medium at certain values of the liquid gate voltage.
Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs
Authors: Chen Zhaoying , Zheng Xiantong , Li Zhilong , Wang Ping , Rong Xin , Wang Tao , Yang Xuelin , Xu Fujun , Qin Zhixin , Ge Weikun , Shen Bo , Wang Xinqiang
Published: August 2016

We report a 23.4% improvement of conversion efficiency in solar cells based on InGaN/GaN multiple quantum wells by using a patterned sapphire substrate in the fabrication process. The efficiency enhancement is due to the improvement of the crystalline quality, as proven by the reduction of the threading dislocation density. More importantly, the better crystalline quality leads to a positive photovoltaic efficiency temperature coefficient up to 423 K, which shows the property and advantage of wide gap semiconductors like InGaN, signifying the potential of III-nitride based solar cells for high temperature and concentrating solar power applications.
Microelectromechanical systems integrating molecular spin crossover actuators
Authors: Manrique-Juarez Maria D. , Rat Sylvain , Mathieu Fabrice , Saya Daisuke , Séguy Isabelle , Leïchlé Thierry , Nicu Liviu , Salmon Lionel , Molnár Gábor , Bousseksou Azzedine
Published: August 2016

Silicon MEMS cantilevers coated with a 200 nm thin layer of the molecular spin crossover complex [Fe(H2B(pz)2)2(phen)] (H2B(pz)2 = dihydrobis(pyrazolyl)borate and phen = 1,10-phenantroline) were actuated using an external magnetic field and their resonance frequency was tracked by means of integrated piezoresistive detection. The light-induced spin-state switching of the molecules from the ground low spin to the metastable high spin state at 10 K led to a well-reproducible shift of the cantilever's resonance frequency (Δfr = −0.52 Hz). Control experiments at different temperatures using coated as well as uncoated devices along with simple calculations support the assignment of this effect to the spin transition. This latter translates into changes in mechanical behavior of the cantilever due to the strong spin-state/lattice coupling. A guideline for the optimization of device parameters is proposed so as to efficiently harness molecular scale movements for large-scale mechanical work, thus paving the road for nanoelectromechanical systems (NEMS) actuators based on molecular materials.
Gradient-index phononic crystal lens-based enhancement of elastic wave energy harvesting
Authors: Tol S. , Degertekin F. L. , Erturk A.
Published: August 2016

We explore the enhancement of structure-borne elastic wave energy harvesting, both numerically and experimentally, by exploiting a Gradient-Index Phononic Crystal Lens (GRIN-PCL) structure. The proposed GRIN-PCL is formed by an array of blind holes with different diameters on an aluminum plate, where the blind hole distribution is tailored to obtain a hyperbolic secant gradient profile of refractive index guided by finite-element simulations of the lowest asymmetric mode Lamb wave band diagrams. Under plane wave excitation from a line source, experimentally measured wave field validates the numerical simulation of wave focusing within the GRIN-PCL domain. A piezoelectric energy harvester disk located at the first focus of the GRIN-PCL yields an order of magnitude larger power output as compared to the baseline case of energy harvesting without the GRIN-PCL on the uniform plate counterpart.
Dual band metamaterial perfect absorber based on Mie resonances
Authors: Liu Xiaoming , Lan Chuwen , Bi Ke , Li Bo , Zhao Qian , Zhou Ji
Published: August 2016

We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric “atom” with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric “atom” and copper plate. Mie resonances of dielectric “atom” provide a simple way to design metamaterial perfect absorbers with high symmetry.
Effect of radial plasma transport at the magnetic throat on axial ion beam formation
Authors: Zhang Yunchao , Charles Christine , Boswell Rod
Published: August 2016

Correlation between radial plasma transport and formation of an axial ion beam has been investigated in a helicon plasma reactor implemented with a convergent-divergent magnetic nozzle. The plasma discharge is sustained under a high magnetic field mode and a low magnetic field mode for which the electron energy probability function, the plasma density, the plasma potential, and the electron temperature are measured at the magnetic throat, and the two field modes show different radial parametric behaviors. Although an axial potential drop occurs in the plasma source for both field modes, an ion beam is only observed in the high field mode while not in the low field mode. The transport of energetic ions is characterized downstream of the plasma source using the delimited ion current and nonlocal ion current. A decay of ion beam strength is also observed in the diffusion chamber.
Towards intrinsic MoS2 devices for high performance arsenite sensing
Authors: Li Peng , Zhang Dongzhi , Sun Yan'e , Chang Hongyan , Liu Jingjing , Yin Nailiang
Published: August 2016

Molybdenum disulphide (MoS2) is one of the most attractive two dimensional materials other than graphene, and the exceptional properties make it a promising candidate for bio/chemical sensing. Nevertheless, intrinsic properties and sensing performances of MoS2 are easily masked by the presence of the Schottky barrier (SB) at source/drain electrodes, and its impact on MoS2 sensors remains unclear. Here, we systematically investigated the influence of the SB on MoS2 sensors, revealing the sensing mechanism of intrinsic MoS2. By utilizing a small work function metal, Ti, to reduce the SB, excellent electrical properties of this 2D material were yielded with 2–3 times enhanced sensitivity. We experimentally demonstrated that the sensitivity of MoS2 is superior to that of graphene. Intrinsic MoS2 was able to realize rapid detection of arsenite down to 0.1 ppb without the influence of large SB, which is two-fold lower than the World Health Organization (WHO) tolerance level and better than the detection limit of recently reported arsenite sensors. Additionally, accurately discriminating target molecules is a great challenge for sensors based on 2D materials. This work demonstrates MoS2 sensors encapsulated with ionophore film which only allows certain types of molecules to selectively permeate through it. As a result, multiplex ion detection with superb selectivity was realized. Our results show prominent advantages of intrinsic MoS2 as a sensing material.
Detection of elastic modes in a solid-liquid-solid planar waveguide
Authors: Ham-Rodriguez C. I. , Manzanares-Martinez J. , Moctezuma-Enriquez D. , Manzanares-Martinez B.
Published: August 2016

In this work, we demonstrate that acoustic ultra-short pulses can be used to characterize multiple guided modes in a solid-liquid-solid planar waveguide via the determination of the time of flight (τ) using the Short Time Fourier Transform (STFT). To obtain experimentally τ, we introduce a time dependent ultra-short acoustic signal s(t) at one side of a finite waveguide and we perform the STFT of the outgoing acoustic signal s′(t) from the other side. We have found that this technique is able to discriminate the signature of multiple even and odd modes at the same experimental run.
Francisellosis in fish: an emerging challenge
Authors: Chong Roger
Published: August 2016

Francisellosis is a bacterial disease with increasing economic impacts in the culture of tilapia and Atlantic cod since emerging in 1992. Two main strains – Francisella noatunensis subsp. orientalis (Fno) and F. noatunensis subsp. noatunensis (Fnn), have been identified, causing both acute and chronic granulomatous systemic disease. The piscine host range is increasing and Francisella culture should be included in routine diagnosis. Differentiation from the major zoonotic F. tularensis and opportunistic zoonotic F. philomiragia when dealing with environmental soil and water samples from fish farms is important. Diagnosis can be challenging but presentation of granulomatous pathology in fish should require use of cysteine supplemented selective media, culture at 15–28°C or culture in fish cell lines and specific PCR to exclude piscine Fno or Fnn. Control of infections in fish rely on appropriate antibiotic selection although in the long term an effective commercial vaccine that includes the pathogenic species of Francisella is required.
Aquaculture: exotic diseases and surveillance
Authors: Jones J Brian
Published: August 2016

Aquaculture is a rapidly growing global industry. Half of all seafood is sourced from aquaculture and Australia is part of the trend. A major emerging threat to this industry is disease.
Pseudomonas anguilliseptica infection as a threat to wild and farmed fish in the Baltic Sea
Authors: Wiklund Tom
Published: August 2016

The transport of live fishes related to the growth of the fish farming industry worldwide may increase the transfer of previously known bacterial pathogens into new geographic areas and new host species, but also facilitate the introduction of completely new bacterial pathogens. Species belonging to the genera Vibrio and Aeromonas are well known in many countries, infecting a large number of fish species. Other bacterial fish pathogens like Pseudomonas anguilliseptica species, up to now considered less harmful, may constitute a potential threat to a developing fish farming industry, especially of European whitefish.
Conserving phylogenetic diversity, with reference to Victorian eucalypts
Authors: McCarthy Michael A. , Pollock Laura J.
Published: August 2016

Preserving the tree of life (i.e. phylogenetic diversity) is increasingly recognised as important in conservation. Australia is a key area for retaining the tree of life because it holds a disproportionately large amount of phylogenetic diversity. We examine the degree to which the phylogenetic diversity of Victorian eucalypts is reserved within conservation areas. Based on modelled distributions of 101 eucalypt species and a phylogeny constructed from four molecular markers, we show that Victoria’s conservation reserve system contains approximately a quarter of the eucalypt phylogenetic diversity. Some species do not exist at all within the reserve system. Large increases in reserved phylogenetic diversity could be achieved with small increases in the area set aside for conservation. Further, we show that any developments within Victoria’s national parks should consider impacts on the reservation of eucalypt phylogenetic diversity.
Phylogenetic studies of eucalypts: fossils, morphology and genomes
Authors: Bayly Michael J.
Published: August 2016

The eucalypt group includes seven genera: Eucalyptus, Corymbia, Angophora, Eucalyptopsis, Stockwellia, Allosyncarpia and Arillastrum. Knowledge of eucalypt phylogeny underpins classification of the group, and facilitates understanding of their ecology, conservation and economic use, as well as providing insight into the history of Australia’s flora. Studies of fossils and phylogenetic analyses of morphological and molecular data have made substantial contributions to understanding of eucalypt relationships and biogeography, but relationships among some genera are still uncertain, and there is controversy about generic circumscription of the bloodwood eucalypts (genus Corymbia). Relationships at lower taxonomic levels, e.g. among sections and series of Eucalyptus, are also not well resolved. Recent advances in DNA sequencing methods offer the ability to obtain large genomic datasets that will enable improved understanding of eucalypt evolution.
Predisposing, enabling and need-for-care predictors of adolescents’ intention to use sexual health services
Authors: Berglas Nancy F. , Hucles Katherine , Constantine Norman A. , Jerman Petra , Rohrbach Louise A.
Published: August 2016

Background: The study aimed to understand the influence of predisposing, enabling and need-for-care factors on adolescents’ intention to use sexual health services, using Andersen’s Behavioural Model of Health Service Utilisation to organise and test these factors. Methods: A sample of predominantly Hispanic teens (n = 600) in Los Angeles, California completed a self-report survey about their sexual health knowledge, beliefs, intentions, and behaviours. Hierarchical regression modelling was used to examine the incremental influences on adolescents’ intention to use sexual health services of: 1) predisposing sociodemographic factors; 2) predisposing knowledge and beliefs about sexual health; 3) enabling factors regarding perceived access to sexual health services; and 4) a need-for-care factor (sexual experience). Results: Adolescents reported high intentions to use sexual health services (3.25 on a 4-point scale), yet only 42% reported knowing where to access services. Sexual health knowledge and beliefs significantly predicted adolescents’ intention to use services beyond the effect of sociodemographics (P < 0.001). Enabling factors indicating awareness of and importance attributed to accessibility significantly predicted intention to use services incremental to predisposing factors (P < 0.001). However, need for care – that is, sexual experience – was not statistically associated with intention to use services (P = 0.402). Conclusions: Sexual health interventions are needed to provide sexual health information, promote positive beliefs about health care, and ensure adolescents’ awareness of and access to sexual health services.
Peroxidation of polyunsaturated fatty acids by lipoxygenases drives ferroptosis
Authors: Yang Wan Seok , Kim Katherine J. , Gaschler Michael M. , Patel Milesh , Shchepinov Mikhail S. , Stockwell Brent R.
Published: August 2016

Significance

Ferroptosis is a regulated form of cell death induced by loss of glutathione peroxidase 4 (GPX4) phospholipid peroxidase activity and lethal accumulation of reactive oxygen species. Small-molecule inhibitors of GPX4 induce ferroptosis; however, the interaction between these inhibitors and GPX4 has remained elusive, as has the identity of the reactive oxygen species that drive execution of ferroptosis. We identified here a ligand-binding site on GPX4 and determined the specific lipids oxidized during ferroptosis. We further identified two key drivers of lipid peroxidation during ferroptosis: lipoxygenases and phosphorylase kinase G2. These findings reveal a previously enigmatic mechanism of ferroptotic lipid peroxide generation and suggest new strategies for pharmacological control of ferroptosis and diseases associated with this mode of cell death.
Histone arginine methylation in cocaine action in the nucleus accumbens
Authors: Damez-Werno Diane M. , Sun HaoSheng , Scobie Kimberly N. , Shao Ningyi , Rabkin Jaclyn , Dias Caroline , Calipari Erin S. , Maze Ian , Pena Catherine J. , Walker Deena M. , Cahill Michael E. , Chandra Ramesh , Gancarz Amy , Mouzon Ezekiell , Landry Joseph A. , Cates Hannah , Lobo Mary-Kay , Dietz David , Allis C. David , Guccione Ernesto , Turecki Gustavo , Defilippi Paola , Neve Rachael L. , Hurd Yasmin L. , Shen Li , Nestler Eric J.
Published: August 2016

Significance

We demonstrate that protein-R (arginine)-methyltransferase-6 (PRMT6) and its associated histone mark, asymmetric dimethylation of R2 on histone H3 (H3R2me2a), are decreased in the nucleus accumbens (NAc) of mice and rats after repeated cocaine exposure, as well as in the NAc of cocaine-addicted humans. We show that cocaine-induced PRMT6 down-regulation occurs selectively in NAc medium spiny neurons expressing dopamine D2 receptors (D2-MSNs) and serves to protect against cocaine-induced behavioral abnormalities. Furthermore, we provide the first, to our knowledge, genome-wide characterization of H3R2me2a within a specific brain region in vivo, and identify Src kinase signaling inhibitor 1 (Srcin1 or p140Cap) as a key target for this chromatin modification. Srcin1 induction in the NAc after cocaine exposure, which is associated with reduced Src signaling, decreases cocaine reward.
Assembly scaffold NifEN: A structural and functional homolog of the nitrogenase catalytic component
Authors: Fay Aaron W. , Blank Michael A. , Rebelein Johannes G. , Lee Chi Chung , Ribbe Markus W. , Hedman Britt , Hodgson Keith O. , Hu Yilin
Published: August 2016

Significance

This work provides direct evidence for the formation of an M-cluster on the assembly scaffold NifEN, establishing NifEN as the second known protein that houses a nitrogenase cofactor. A “half-on, half-off” scheme of cofactor biosynthesis can be proposed based on the outcome of this study, which suggests an asymmetric nature of the assembly sites in the seemingly equivalent αβ-halves of NifEN and a coordination of various biosynthetic events via a unique conformational switch on/off mechanism. The comparable substrate-reducing capabilities of NifEN and NifDK establish the former as a structural and functional homolog of the latter, providing a proof-of-concept for the feasibility of probing key catalytic features of NifDK via reconstruction of a NifDK equivalent on the basis of a “simplified” template, NifEN.
Sport science integration: An evolutionary synthesis
Authors: Balagué N. , Torrents C. , Hristovski R. , Kelso J. A. S.
Published: August 2016

The aim of the paper is to point out one way of integrating the supposedly incommensurate disciplines investigated in sports science. General, common principles can be found among apparently unrelated disciplines when the focus is put on the dynamics of sports‐related phenomena. Dynamical systems approaches that have recently changed research in biological and social sciences among others, offer key concepts to create a common pluricontextual language in sport science. This common language, far from being homogenising, offers key synthesis between diverse fields, respecting and enabling the theoretical and experimental pluralism. It forms a softly integrated sports science characterised by a basic dynamic explanatory backbone as well as context‐dependent theoretical flexibility. After defining the dynamic integration in living systems, unable to be captured by structural static approaches, we show the commonalities between the diversity of processes existing on different levels and time scales in biological and social entities. We justify our interpretation by drawing on some recent scientific contributions that use the same general principles and concepts, and diverse methods and techniques of data analysis, to study different types of phenomena in diverse disciplines. We show how the introduction of the dynamic framework in sport science has started to blur the boundaries between physiology, biomechanics, psychology, phenomenology and sociology. The advantages and difficulties of sport science integration and its consequences in research are also discussed.
Automated identification of antibiotic overdoses and adverse drug events via analysis of prescribing alerts and medication administration records
Authors: Kirkendall Eric S , Kouril Michal , Dexheimer Judith W , Courter Joshua D , Hagedorn Philip , Szczesniak Rhonda , Li Dan , Damania Rahul , Minich Thomas , Spooner S Andrew
Published: August 2016

Objectives: Electronic trigger detection tools hold promise to reduce Adverse drug event (ADEs) through efficiencies of scale and real-time reporting. We hypothesized that such a tool could automatically detect medication dosing errors as well as manage and evaluate dosing rule modifications.

Materials and Methods: We created an order and alert analysis system that identified antibiotic medication orders and evaluated user response to dosing alerts. Orders associated with overridden alerts were examined for evidence of administration and the delivered dose was compared to pharmacy-derived dosing rules to confirm true overdoses. True overdose cases were reviewed for association with known ADEs.

Results: Of 55 546 orders reviewed, 539 were true overdose orders, which lead to 1965 known overdose administrations. Documentation of loose stools and diarrhea was significantly increased following drug administration in the overdose group. Dosing rule thresholds were altered to reflect clinically accurate dosing. These rule changes decreased overall alert burden and improved the salience of alerts.

Discussion: Electronic algorithm-based detection systems can identify antibiotic overdoses that are clinically relevant and are associated with known ADEs. The system also serves as a platform for evaluating the effects of modifying electronic dosing rules. These modifications lead to decreased alert burden and improvements in response to decision support alerts.

Conclusion: The success of this test case suggests that gains are possible in reducing medication errors and improving patient safety with automated algorithm-based detection systems. Follow-up studies will determine if the positive effects of the system persist and if these changes lead to improved safety outcomes.
Supporting LGBT nurses
Authors: Lim Fidelindo A. , Borski Daniel Brian
Published: August 2016

Find out how to respond appropriately when patients express bigotry at the bedside.
Toward a Holistic Approach to Spiritual Health Care for People With Schizophrenia
Authors: Ho Rainbow T. H. , Wan Adrian H. Y. , Chan Caitlin K. P.
Published: August 2016

Medical and behavioral treatments are the predominant types of rehabilitation services for people with schizophrenia. Spirituality in people with schizophrenia remains poorly conceptualized, thereby limiting knowledge advancement in the area of spiritual health care services. To provide a framework for better clinical and research practices, we advocate a holistic approach to investigating spirituality and its application in spiritual health care services of people with schizophrenia.
Trabeculectomy and Combined Phacoemulsification-Trabeculectomy: Outcomes and Risk Factors for Failure in Primary Angle Closure Glaucoma
Authors: Song Brian J. , Ramanathan Meera , Morales Esteban , Law Simon K. , Giaconi JoAnn A. , Coleman Anne L. , Caprioli Joseph
Published: August 2016

Purpose:

To evaluate tonometric outcomes of patients with primary angle closure glaucoma (PACG) who have undergone trabeculectomy with mitomycin C (MMC) with and without concurrent phacoemulsification and to identify risk factors for postoperative failure.

Patients and Methods:

Retrospective cohort study of 44 eyes of 33 phakic patients who underwent trabeculectomy with MMC with or without combined phacoemulsification for PACG. The primary endpoint was qualified tonometric success at 12 months according to predefined criteria. LogMAR visual acuity, number of glaucoma medications, and postoperative complications were also evaluated. Cox proportional hazard regression analysis was performed to identify potential risk factors for trabeculectomy failure.

Results:

Mean intraocular pressure (IOP) decreased from 21.3±7.9 to 12.2±3.9 mm Hg at 12 months (P<0.001) in all patients. A significant reduction in mean number of glaucoma medications (P<0.001) was also seen. There was no change in logMAR visual acuity (P=0.39) after 12 months. There were no significant intergroup differences in mean IOP (P=0.42), number of glaucoma medications (P=0.85), or logMAR visual acuity (P=0.42) between the trabeculectomy versus combined surgery groups after 12 months. Increased age, greater baseline IOP, limbus-based conjunctival flaps, and MMC duration >1 minute were associated with decreased risk of surgical failure. Concurrent phacoemulsification at the time of trabeculectomy did not alter tonometric success or rate of complications.

Conclusions:

In phakic patients with PACG, trabeculectomy with MMC significantly reduces IOP and number of glaucoma medications at 12 months without change in visual acuity. However, success rates are modest when based on more demanding tonometric criteria.
Mycobacterium goodii: An Emerging Nosocomial Pathogen
Authors: Salas Natalie Mariam , Klein Nicole
Published: August 2016

Mycobacterium goodii, a rapidly growing nontuberculous mycobacterium, is an emerging pathogen in nosocomial infections. Its inherent resistance patterns make it a challenging organism to treat, and delays in identification can lead to poor outcomes. We present a case of cardiac device pocket infection with M. goodii, complicated by both antibiotic resistance and drug reactions that highlight the challenges faced by clinicians trying to eradicate these infections. We also present a brief review of the English literature surrounding this disease, including a table of all reported cases of M. goodii infections and their outcomes to act as guide for clinicians formulating treatment plans for these infections. A clear understanding of diagnostic methods and treatment caveats is essential to curing infections caused by these organisms.
Clinical risk factors for delayed bleeding after endoscopic submucosal dissection for colorectal tumors in Japanese patients
Authors: Ogasawara Naotaka , Yoshimine Takashi , Noda Hisatsugu , Kondo Yoshihiro , Izawa Shinya , Shinmura Tetsuya , Ebi Masahide , Funaki Yasushi , Sasaki Makoto , Kasugai Kunio
Published: August 2016

Background

Endoscopic submucosal dissection (ESD) is a curative, standard therapy for colorectal neoplasms. Some studies have investigated the risk factors for perforation during colorectal ESD. However, few studies have assessed the risk factors for delayed bleeding after colorectal ESD. We studied patients undergoing ESD for colorectal epithelial neoplasms to identify the risk factors for post-ESD bleeding.

Patients and methods

We studied 124 consecutive patients undergoing ESD for colorectal epithelial neoplasms. To identify risk factors for delayed bleeding post-ESD, recurrent bleeding post-ESD was compared with patient-related and tumor-related factors.

Results

Delayed bleeding after ESD occurred in 10 (8.1%) lesions of 124 colorectal tumors, and the median time from the end of ESD to the onset of bleeding was 18.5 h. Delayed bleeding was significantly higher in tumors located in rectums than in colons (P=0.021), and the number of occurrences of arterial bleeding during ESD was significantly higher in the delayed bleeding group than in the nondelayed bleeding group (P=0.002). The procedure time was significantly longer in the delayed bleeding group than in the nondelayed bleeding group (P=0.012). On multivariate logistic regression analysis, tumor location (odds ratio, 10.13; 95% confidence interval, 1.18–87.03; P=0.035) and three or more occurrences of arterial bleeding during ESD (odds ratio, 6.86; 95% confidence interval, 1.13–41.5; P=0.036) were significant independent risk factors for delayed bleeding.

Conclusion

The presence of lesions in the rectum and three or more arterial bleeding occurrences during ESD were risk factors for post-ESD bleeding. Patients with these risk factors should be followed up carefully after ESD for colorectal epithelial neoplasms.
Déjà vu? A Comparison of Syphilis Outbreaks in Houston, Texas
Authors: Hallmark Camden J. , Hill Mandy J. , Luswata Charles , Watkins Kellie L. , Thornton Lupita , McNeese Marlene , Ross Michael W.
Published: August 2016

Background

After reaching an all-time low in 2000, syphilis incidence in the United States has increased as the burden shifted from heterosexuals to men who have sex with men (MSM). Houston, Texas, experienced 2 outbreaks of syphilis during this transformation in trends. Further evaluation is necessary to determine if these outbreaks occurred among the same subpopulations.

Methods

Surveillance data collected on all reported infectious syphilis cases in Houston from 1971 to 2013 were analyzed. Trends in incidence among MSM and human immunodeficiency virus-positive Houston residents were examined. Peak syphilis years subsequent to 1999, years 2007 and 2012, were compared to determine if outbreaks arose in distinctive subpopulations. Categorical variables between these years were compared using chi-square and Fisher's exact tests, whereas further associations between the years were evaluated using multivariable logistic regression.

Results

Incidence among MSM was 20.9 to 32.1 times higher than other men from 2005 to 2013. After adjusting for covariates, cases in 2012 were significantly more likely to be Hispanic (adjusted odds ratio [AOR] = 1.61; 95% confidence interval [95% CI], 1.03–2.53), reported meeting partners via the Internet (AOR, 1.74; 95% CI, 1.18–2.58), and engaged in anonymous sex (AOR, 1.92; 95% CI, 1.40–2.63) in comparison to cases in 2007.

Conclusions

We found marked disparities of syphilis by subpopulation in Houston. Herein, we present evidence that outbreaks have been distinct in a major southern city with a high burden of syphilis.
RNase H enables efficient repair of R-loop induced DNA damage
Authors: Amon Jeremy D. , Koshland Douglas
Published: August 2016

R-loops, three-stranded structures that form when transcripts hybridize to chromosomal DNA, are potent agents of genome instability. This instability has been explained by the ability of R-loops to induce DNA damage. Here, we show that persistent R-loops also compromise DNA repair. Depleting endogenous RNase H activity impairs R-loop removal in budding yeast, causing DNA damage that occurs preferentially in the repetitive ribosomal DNA locus (rDNA). We analyzed the repair kinetics of this damage and identified mutants that modulate repair. Our results indicate that persistent R-loops in the rDNA induce damage that is slowly repaired by break-induced replication (BIR). Furthermore, R-loop induced BIR at the rDNA leads to lethal repair intermediates when RNA polymerase I elongation is compromised. We present a model to explain how removal of R-loops by RNase H is critical in ensuring the efficient repair of R-loop induced DNA damage by pathways other than BIR.