bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlled size and morphology, and phase transition of YF3:Yb3+,Er3+ and YOF:Yb3+,Er3+ nanocrystals for fine color tuning
Authors: Zhu Yongsheng , Xu Wen , Cui Shaobo , Liu Mao , Lu Cheng , Song Hongwei , Kim Dong-Hwan
Published: November 2015

Rare-earth (RE) based fluoride and oxyfluoride upconversion nanocrystals (UCNCs) have the ability to generate multicolor visible emission as well as a wide range of applications under near-infrared excitation.
Identifikation systemweiter Kontaminationen mit Legionella spec. in Trinkwasser-Installationen: Untersuchungsstrategien und korrespondierende Parameter
Authors: Völker S. , Schreiber C. , Müller H. , Zacharias N. , Kistemann T.
Published: November 2015

Nach der Novellierung der Trinkwasserverordnung im Jahr 2011 sind die Anforderungen an die hygienisch-mikrobiologische Überwachung von Trinkwasser-Installationen nochmals erheblich gestiegen. Im BMBF-geförderten Projekt „Biofilm-Management“ (2010–2014) untersuchten wir, inwieweit etablierte Probenahmestrategien in der Praxis systemweit mit Legionellen kontaminierte Trinkwasser-Installationen aufdecken können, und welche zusätzlichen Parameter geeignet sind, eine systemweite Kontamination zu erfassen. Wir unterzogen die Trinkwasser-Installation von 8 Gebäuden mit bekannter mikrobieller Kontamination (Legionellen) einer intensiven hygienisch-mikrobiologischen Beprobung mit hoher räumlicher und zeitlicher Auflösung. Insgesamt wurden 626 Trinkwarmwasser-Proben mit klassischen kulturellen Verfahren untersucht. Außerdem wurden in jedem Gebäude eine umfassende hygienische Ortsbesichtigung durchgeführt und qualitative Interviews mit Betreibern und Nutzern geführt. Erhobene zapfstellenspezifische Parameter wurden quantitativ mittels Sensitivitäts- und Korrektklassifikationsberechnungen analysiert. Das systemweite Vorkommen von Legionellen in Trinkwasser-Installationen weist eine hohe räumliche und zeitliche Variabilität auf. Etablierte Probenahmestrategien waren nur eingeschränkt geeignet, langfristig bestehende Legionellen-Kontaminationen von Trinkwasser-Installationen zu detektieren. Insbesondere die Beprobung von Warmwasser-Vorlauf und Zirkulationsrücklauf zeigte wenig Aussagekraft hinsichtlich des Kontaminationsgeschehens. Deutlich besser ließ sich eine systemweite Legionellen-Kontamination mittels der Parameter Stagnation (qualitativ) und Temperatur (Einhaltung der 5K-Regel) aufzeigen.
Development of superconducting magnets for RAON 28 GHz ECR ion source
Authors: Heo Jeongil , Choi Sukjin , Kim Yonghwan , Hong In-Seok
Published: November 2015

RAON, a 28 GHz electron cyclotron resonance ion source (ECR IS), was designed and tested as a Rare Isotope Science Project. It is expected that RAON would provide not only rare-isotope beams but also stable heavy ions ranging from protons to uranium. In order to obtain the steady heavy-ion beam required for ECR IS, we must use a 28 GHz microwave source as well as a high magnetic field. A superconducting magnet using a NbTi wire was designed and manufactured for producing the ECR IS and a test was conducted. In this paper, the design and fabrication of the superconducting magnet for the ECR IS are presented. Experimental results show that the quench current increases whenever quenching occurs, but it has not yet reached the designed current. The experiment is expected to reveal the ideal conditions required to reach the designed current.
Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus
Authors: Fang Zhao-Xiang , Ren Yu-Xuan , Gong Lei , Vaveliuk Pablo , Chen Yue , Lu Rong-De
Published: November 2015

Needle-like electromagnetic field has various advantages for the applications in high-resolution imaging, Raman spectroscopy, as well as long-distance optical transportation. The realization of such field often requires high numerical aperture (NA) objective lens and the transmission masks. We demonstrate an ultralong needle-like focus in the optical range produced with an ordinary lens. This is achieved by focusing a symmetric Airy beam (SAB) generated via binary spectral modulation with a digital micromirror device. Such amplitude modulation technique is able to shape traditional Airy beams, SABs, as well as the dynamic transition modes between the one-dimensional and two-dimensional (2D) symmetric Airy modes. The created 2D SAB was characterized through measurement of the propagating fields with one of the four main lobes blocked by an opaque mask. The 2D SAB was verified to exhibit self-healing property against propagation with the obstructed major lobe reconstructed after a certain distance. We further produced an elongated focal line by concentrating the SAB via lenses with different NAs and achieved an ultralong longitudinal needle focus. The produced long needle focus will be applied in optical, chemical, and biological sciences.
Quasi-discrete particle motion in an externally imposed, ordered structure in a dusty plasma at high magnetic field
Authors: Thomas Edward , Konopka Uwe , Lynch Brian , Adams Stephen , LeBlanc Spencer , Merlino Robert L. , Rosenberg Marlene
Published: November 2015

Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas at magnetic fields up to 2.5 T where the electrons and ions are strongly magnetized. Plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper electrode supports a dual mesh consisting of #24 brass and #30 aluminum wire cloth. In this experiment, we study the formation of imposed ordered structures and particle dynamics as a function of magnetic field. Through observations of trapped particles and the quasi-discrete (i.e., “hopping”) motion of particles between the trapping locations, it is possible to make a preliminary estimate of the potential structure that confines the particles to a grid structure in the plasma. This information is used to gain insight into the formation of the imposed grid pattern of the dust particles in the plasma.
Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals
Authors: Zuehlsdorff T. J. , Hine N. D. M. , Payne M. C. , Haynes P. D.
Published: November 2015

We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.
Mid-infrared photodetection in an AlGaAs/GaAs quantum-well infrared photodetector using photoinduced noise
Authors: Fernandes F. M. , da Silva E. C. F. , Quivy A. A.
Published: November 2015

We propose a new way to assess the output signal of a quantum-well infrared photodetector (QWIP). Instead of measuring the photocurrent produced by the device, as usually done, we show that the noise induced by the absorption process can be used to generate a useful detection signal. We built a simple electronic circuit able to quantify the noise of an AlGaAs/GaAs QWIP that was intentionally designed to produce no photocurrent at all, and we demonstrated that such a circuit was able to generate a strong output signal whenever an infrared radiation of a specific wavelength was shed on the detector. This concept opens new possibilities for the design of novel types of photodetection systems.
On the role of spatial position of bridged oxygen atoms as surface passivants on the ground-state gap and photo-absorption spectrum of silicon nano-crystals
Authors: Nazemi Sanaz , Pourfath Mahdi , Soleimani Ebrahim Asl , Kosina Hans
Published: November 2015

Silicon nano-crystals (NCs) are potential candidates for enhancing and tuning optical properties of silicon for optoelectronic and photo-voltaic applications. Due to the high surface-to-volume ratio, however, optical properties of NC result from the interplay of quantum confinement and surface effects. In this work, we show that both the spatial position of surface terminants and their relative positions have strong effects on NC properties as well. This is accomplished by investigating the ground-state HOMO-LUMO band-gap, the photo-absorption spectra, and the localization and overlap of HOMO and LUMO orbital densities for prototype ∼1.2 nm Si32–xH42–2xOx hydrogenated silicon NC with bridged oxygen atoms as surface terminations. It is demonstrated that the surface passivation geometry significantly alters the localization center and thus the overlap of frontier molecular orbitals, which correspondingly modifies the electronic and optical properties of NC.
Multi-frequency inversion-charge pumping for charge separation and mobility analysis in high-k/InGaAs metal-oxide-semiconductor field-effect transistors
Authors: Djara V. , Cherkaoui K. , Negara M. A. , Hurley P. K.
Published: November 2015

An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (Ninv) from the trapped charge density in high-k/InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed Id-Vg measurements enabled an accurate effective mobility vs Ninv extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs.
Modeling the spectral shape of InGaAlP-based red light-emitting diodes
Authors: Vaskuri Anna , Baumgartner Hans , Kärhä Petri , Andor György , Ikonen Erkki
Published: November 2015

We have developed a spectral model for describing the shape of the emission spectrum of InGaAlP-based red light-emitting diodes (LEDs) with quantum-well structure. The model is based on Maxwell-Boltzmann distribution with junction temperature Tj and an experimental two-dimensional joint density of states (DOS). We model the DOS with a sum of two exponentially broadened step functions describing the two lowest sub-bands in semiconductor quantum well. The relative locations ΔE1 = 0 meV and ΔE2 = 112.7 meV above the band gap energy Eg = 1.983 eV and the ratio 2.13 of the step heights were fixed using an experimental DOS extracted from a LED spectrum measured at known Tj and driving current I. The model can then be fitted to other spectra of other LED samples at varied Tj and I by varying the fitting parameters Eg, Tj, and the broadening of the sub-band edges. The model was tested for three LED samples over I = 200–370 mA and Tj = 303–398 K. Junction temperatures obtained by modeling were compared with calibrated Tj obtained by the forward voltage method. The mean absolute difference was about 2.9 K (0.8%) over the whole region studied and the maximum difference was 8.5 K. The thermal coefficient measured for Eg was −0.509 meV K−1. For the first and second sub-band edges, the thermal broadening coefficients were 18 μeV K−1 and 37 μeV K−1, respectively.
Polarization-dependent differential reflectance spectroscopy for real-time monitoring of organic thin film growth
Authors: Navarro-Quezada A. , Aiglinger M. , Ghanbari E. , Wagner Th. , Zeppenfeld P.
Published: November 2015

By monitoring the reflectance of a sample surface during deposition of a thin organic film, one can obtain information with submonolayer resolution in real-time. A special kind of optical spectroscopy is Differential Reflectance Spectroscopy (DRS), which compares the reflectance before and during deposition of a thin film or any other change of the surface optical properties. In this work, we present an extended DRS setup that allows monitoring simultaneously both linear polarization states (s and p) of the reflected light. We implement polarization-dependent DRS to monitor the growth of perflouropentacene thin films on a Ag(110) single crystal. The setup allows us to deduce the optical anisotropy of the sample and, in particular, the preferred orientation of the molecules on the surface.
Surface-enhanced Raman scattering activity of niobium surface after irradiation with femtosecond laser pulses
Authors: Ivanov Victor G. , Vlakhov Emil S. , Stan George E. , Zamfirescu Marian , Albu Catalina , Mihailescu Natalia , Negut Irina , Luculescu Catalin , Socol Marcela , Ristoscu Carmen , Mihailescu Ion N.
Published: November 2015

The chemical modification of the niobium (Nb) surface after irradiation with femtosecond laser pulses was investigated by scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, grazing incidence X-ray diffraction, and micro-Raman spectroscopy. The physical-chemical analyses indicated that the laser treatment results in oxidation of the Nb surface, as well as in the formation of Nb hydrides. Remarkably, after the samples' washing in ethanol, a strong Surface-Enhanced Raman Scattering (SERS) signal originating from the toluene residual traces was evidenced. Further, it was observed that the laser irradiated Nb surface is able to provide a SERS enhancement of ∼1.3 × 103 times for rhodamine 6G solutions. Thus, for the first time it was shown that Nb/Nb oxide surfaces could exhibit SERS functionality, and so one can expect applications in biological/biochemical screening or for sensing of dangerous environmental substances.
Site preference and magnetic properties of Ga/In-substituted strontium hexaferrite: An ab initio study
Authors: Dixit Vivek , Nandadasa Chandani N. , Kim Seong-Gon , Kim Sungho , Park Jihoon , Hong Yang-Ki
Published: November 2015

The first-principles density functional theory has been used to study Ga/In-substituted strontium hexaferrite (SrFe12O19). Based on the calculation of the substitution energy of Ga and In in SrFe12O19 and the formation probability analysis, we conclude that in SrFe12−xGaxO19 the substituted Ga atoms prefer to occupy the 12k, 2a, and 4f1 sites, while In atoms in SrFe12−xInxO19 occupy the 12k, 4f2, and 4f1 sites. We used the site occupation probabilities to calculate the magnetic properties of the substituted SrFe12O19. It was found that as the fraction of Ga atoms in SrFe12−xGaxO19 increases, the saturation magnetization (Ms) as well as magnetic anisotropy energy (MAE) decrease, while the anisotropy field (Ha) increases. In the case of SrFe12−xInxO19, Ms, MAE, and Ha decrease with an increase of the concentration of In atoms.
Ultralow bias power all-optical photonic crystal memory realized with systematically tuned L3 nanocavity
Authors: Kuramochi Eiichi , Nozaki Kengo , Shinya Akihiko , Taniyama Hideaki , Takeda Koji , Sato Tomonari , Matsuo Shinji , Notomi Masaya
Published: November 2015

An InP photonic crystal nanocavity with an embedded InGaAsP active region is a unique technology that has realized an all-optical memory with a sub-micro-watt operating power and limitless storage time. In this study, we employed an L3 design with systematic multi-hole tuning, which realized a higher loaded Q factor (>40 000) and a lower mode volume (0.9 μm3) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm3). Excluding the active region realized a record loaded Q factor (210 000) in all for InP-based nanocavities. The minimum bias power for bistable memory operation was reduced to 2.3 ± 0.3 nW, which is about 1/10 of the previous record of 30 nW. This work further established the capability of a bistable nanocavity memory for use in future ultralow-power-consumption on-chip integrated photonics.
Sub-micron strain analysis of local stick-slip motion of individual shear bands in a bulk metallic glass
Authors: Binkowski I. , Schlottbom S. , Leuthold J. , Ostendorp S. , Divinski S. V. , Wilde G.
Published: November 2015

Nanodot deposition on a side surface of a rectangular sample and digital image correlation are used to quantify the in-plane strain fields associated with the propagation of a shear band in a PdNiP bulk metallic glass, induced by rolling. Within the resolution of the method related to an average inter-dot distance of 100 nm, deformation is found to be highly localized at the shear bands, while alternating areas with a size of 100–400 nm with opposite local shear strains are found. This phenomenon substantiates a local stick-slip nature of shear band propagation during the metallic glass deformation, even during rolling.
Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure
Authors: Wu Zheng , Chen Juguang , Ji Mengxi , Huang Qingzhong , Xia Jinsong , Wu Ying , Wang Yi
Published: November 2015

An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (QL) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.
Micromagnetic study of excitation modes of an artificial skyrmion crystal
Authors: Miao B. F. , Wen Y. , Yan M. , Sun L. , Cao R. X. , Wu D. , You B. , Jiang Z. S. , Ding H. F.
Published: November 2015

We present a micromagnetic study on the eigen excitations of an artificial skyrmion crystal, which has been experimentally confirmed to be stable at room temperature without the need of any Dzyaloshinsky-Moriya interaction (DMI). Three in-plane rotational modes and one breathing-type mode are identified. We find the intrinsic origin of the dynamics of skyrmion crystal is the nontrivial magnetic texture instead of DMI. And the rotational direction of a skyrmion is solely determined by the sign of the skyrmion number, irrespective of its circulation sense, evidencing the topological nature of the magnetic skyrmion.
Resonant tunnelling features in a suspended silicon nanowire single-hole transistor
Authors: Llobet Jordi , Krali Emiljana , Wang Chen , Arbiol Jordi , Jones Mervyn E. , Pérez-Murano Francesc , Durrani Zahid A. K.
Published: November 2015

Suspended silicon nanowires have significant potential for a broad spectrum of device applications. A suspended p-type Si nanowire incorporating Si nanocrystal quantum dots has been used to form a single-hole transistor. Transistor fabrication uses a novel and rapid process, based on focused gallium ion beam exposure and anisotropic wet etching, generating <10 nm nanocrystals inside suspended Si nanowires. Electrical characteristics at 10 K show Coulomb diamonds with charging energy ∼27 meV, associated with a single dominant nanocrystal. Resonant tunnelling features with energy spacing ∼10 meV are observed, parallel to both diamond edges. These may be associated either with excited states or hole–acoustic phonon interactions, in the nanocrystal. In the latter case, the energy spacing corresponds well with reported Raman spectroscopy results and phonon spectra calculations.
Broadband manipulation of acoustic wavefronts by pentamode metasurface
Authors: Tian Ye , Wei Qi , Cheng Ying , Xu Zheng , Liu Xiaojun
Published: November 2015

An acoustic metasurface with a sub-wavelength thickness can manipulate acoustic wavefronts freely by the introduction of abrupt phase variation. However, the existence of a narrow bandwidth and a low transmittance limits further applications. Here, we present a broadband and highly transparent acoustic metasurface based on a frequency-independent generalized acoustic Snell's law and pentamode metamaterials. The proposal employs a gradient velocity to redirect refracted waves and pentamode metamaterials to improve impedance matching between the metasurface and the background medium. Excellent wavefront manipulation based on the metasurface is further demonstrated by anomalous refraction, generation of non-diffracting Bessel beam, and sub-wavelength flat focusing.
Pauli-limited effect in the magnetic phase diagram of FeSexTe1−x thin films
Authors: Zhuang J. C. , Li Z. , Xu X. , Wang L. , Yeoh W. K. , Xing X. Z. , Shi Z. X. , Wang X. L. , Du Y. , Dou S. X.
Published: November 2015

We present a detailed investigation on the doping dependence of the upper critical field Hc2(T) of FeSexTe1−x thin films (0.18 ≤ x ≤ 0.90) by measuring the electrical resistivity as a function of magnetic field. The Hc2(T) curves exhibit a downturn behavior with decreasing temperature in all the samples, owing to the Pauli-limited effect (spin paramagnetic effect). The Pauli-limited effect on the upper critical field can be monotonically modulated by variation of the Se/Te composition. Our results show that Te-doping induced disorder and excess Fe atoms give rise to enhancement of the Pauli-limited effect.
Identification of an organic semiconductor superlattice structure of pentacene and perfluoro-pentacene through resonant and non-resonant X-ray scattering
Authors: Kowarik S. , Hinderhofer A. , Wang C. , Weber C. , Gerlach A. , Hexemer A. , Leone S. R. , Schreiber F.
Published: November 2015

Highly crystalline and stable molecular superlattices are grown with the smallest possible stacking period using monolayers (MLs) of the organic semiconductors pentacene (PEN) and perfluoro-pentacene (PFP). Superlattice reflections in X-ray reflectivity and their energy dependence in resonant soft X-ray reflectivity measurements show that PFP and PEN MLs indeed alternate even though the coherent ordering is lost after ∼ 4 ML. The observed lattice spacing of 15.9 Å in the superlattice is larger than in pure PEN and PFP films, presumably because of more upright standing molecules and lack of interdigitation between the incommensurate crystalline PEN and PFP layers. The findings are important for the development of novel organic quantum optoelectronic devices.
Thermal magnetic noise spectra of nanoparticle ensembles
Authors: Leliaert J. , Coene A. , Liebl M. , Eberbeck D. , Steinhoff U. , Wiekhorst F. , Fischer B. , Dupré L. , Van Waeyenberge B.
Published: November 2015

Typically, the dynamic behaviour of magnetic nanoparticles is investigated by measuring their response to externally applied magnetic fields. In contrast, we present a study of the magnetic fluctuations in an ensemble of magnetic nanoparticles recorded in the absence of any external excitation. Several samples of magnetic nanoparticles with varying particle size, composition, and environment were investigated. We interpret the thermal magnetic noise spectrum to estimate particle size distributions and compare these to the distributions derived from magnetorelaxometry measurements of the same samples.
Problems with using mean germination time to calculate rate of seed germination
Authors: Soltani Elias , Ghaderi-Far Farshid , Baskin Carol C. , Baskin Jerry M.
Published: November 2015

Seed scientists and other plant biologists are interested in the measurement of germination because seeds from different individuals, populations, seed lots and treatments can differ in germination percentages, rate (speed) and uniformity. Mean time to germination (MGT) is a measure of the rate and time-spread of germination; however, there is a problem with using this method to calculate germination rate. MGT does not show the time from the start of imbibition to a specific germination percentage. MGT has been used to compare specific pairs or groups of means and to evaluate seed vigour. However, it is not the real time to mean germination but just an index of germination speed. Using MGT is not correct for ANOVA, post-ANOVA or the other comparison tests, because it does not show time to a specific germination percentage. Thus, we recommend that t50 be used instead of MGT. The t50 has all benefits of MGT, but it does not have the problems of MGT in treatment comparisons.
Moss and vascular epiphyte distributions over host tree and elevation gradients in Australian subtropical rainforest
Authors: Sanger Jennifer C. , Kirkpatrick James B.
Published: November 2015

There is a lack of comprehensive studies on the ecology of epiphytic flora in Australia’s rainforests. Globally, rainforest epiphyte distribution is determined by three main factors: micro-climate within the host tree; landscape changes in macro-climate; and the characteristics of the host tree. We tested the influence of these factors on the species richness and composition of vascular and non-vascular epiphytes in the subtropical rainforest of the Border Ranges in New South Wales. Vascular epiphytes and mosses were recorded in situ from four height zones, with 10 trees sampled at five elevations between 300 and 1100 m above sea level (asl). Vascular epiphyte species richness was highest in the inner canopy (6.3 species), whereas mosses tended to have a uniform distribution over the height zones (3.8–5.0 species). We found that both moss and vascular epiphyte species richness peaked at mid-elevations (500–700 m), with moss richness at a slightly higher elevation than the vascular epiphytes. Host tree characteristics (bark roughness, host size) explained very little of the species composition or richness of epiphytes. Strong patterns in species richness and composition over host tree and elevation gradients suggest that moisture, temperature and light may be the major influences on epiphyte distributions in the Border Ranges.
Toxicity of engineered copper (Cu0) nanoparticles to the green alga Chlamydomonas reinhardtii
Authors: Müller Emanuel , Behra Renata , Sigg Laura
Published: November 2015

Environmental context
Engineered copper nanoparticles are presently under development for various uses and may thus be finally released into the aquatic environment. Copper is well known to be both an essential and a toxic element for aquatic organisms. Here, we investigate the toxicity of copper nanoparticles to a green alga and compare it with the toxicity of dissolved copper.

Abstract
The toxicity of carbon-coated copper nanoparticles (CuNPs) to the unicellular green alga Chlamydomonas reinhardtii was investigated and compared with effects of dissolved Cu2+. The CuNPs with an original size of 6–7nm rapidly agglomerated in the medium to average particle sizes of 140–200nm. Dissolved Cu from CuNPs increased over 2h to 1–2% of total Cu. The photosynthetic yield of C. reinhardtii strongly decreased after exposure for 1 or 2h to dissolved CuII in the concentration range 0.1–10μM, whereas this decrease occurred in the total Cu concentration range 1–100μM after exposure to CuNPs. Effects of CuNPs were compared with those of dissolved CuII on the basis of dissolution experiments. CuNP effects on photosynthetic yield were similar or somewhat stronger for the same dissolved Cu2+ concentration. Addition of EDTA as a strong ligand for CuII suppressed the toxicity of dissolved CuII and of CuNPs. These results thus indicate effects on the algae are mostly from free Cu2+.
Lead solubility in seawater: an experimental study
Authors: Angel Brad M. , Apte Simon C. , Batley Graeme E. , Raven Mark D.
Published: November 2015

Environmental contextMany trace metals including lead are only sparingly soluble in seawater and may exist in both dissolved and particulate forms (e.g. as precipitates). Aquatic organisms may experience different toxic effects from exposure to dissolved and particulate trace metals. This study reports the limits to lead solubility in seawater that influence the exposure to these forms of lead in the field and the laboratory.
AbstractA combination of laboratory investigations and thermodynamic modelling were conducted in order to gain an understanding of the factors controlling lead solubility in seawater. In experiments where increasing amounts of lead were added to seawater (in order to avoid supersaturation) and equilibrated for up to 28 days, the maximum solubility was ~2mgL–1 (pH 8.15, 22°C). However, at higher added lead concentrations, which caused the rapid formation of lead precipitates, the solution chemistry became dynamic and the observed solubility was markedly lower, varying with both reaction time and precipitate concentration. For instance, when seawater solutions were spiked with 10mgL–1 of total lead, precipitation occurred immediately and only 1.6mgL–1 of dissolved lead was measured after 1h, with this concentration decreasing to 1.3mgL–1 after 28 days. The solubility of lead in artificial seawater (0.68mgL–1) was much lower than in natural seawater. This difference was attributed to the significant role played by natural organic matter in complexing dissolved lead. X-Ray diffraction and elemental analysis data suggest that the phase controlling lead solubility is a previously unidentified lead chlorocarbonate, which rapidly transforms to hydrocerussite on washing with deionised water. These observations are of particular relevance to toxicity tests where organisms are exposed to wide ranges of metal concentrations in order to obtain dose–response curves.
Collectives’ and individuals’ obligations: a parity argument
Authors: Collins Stephanie , Lawford-Smith Holly
Published: November 2015

Individuals have various kinds of obligations: keep promises, don’t cause harm, return benefits received from injustices, be partial to loved ones, help the needy and so on. How does this work for group agents? There are two questions here. The first is whether groups can bear the same kinds of obligations as individuals. The second is whether groups’ pro tanto obligations plug into what they all-things-considered ought to do to the same degree that individuals’ pro tanto obligations plug into what they all-things-considered ought to do. We argue for parity on both counts.
Recovery of a Surf Clam Donax deltoides Population in Southern Australia: Successful Outcomes of Fishery-Independent Surveys
Authors: Ferguson Greg J. , Ward Tim M. , Gorman Daniel
Published: November 2015

Estimates of biomass or relative biomass are required for monitoring the recovery of depleted bivalve resources and for the management of newly exploited resources. Uncertainty around fishery catch per unit effort (CPUE) as a proxy for biomass highlights the need for fishery-independent assessments. Following a prolonged period of decline in Australia's largest fishery for surf clam Donax deltoides, robust estimates of biomass were required to monitor recovery and to set appropriate total allowable commercial catches. Estimates of relative biomass were derived from fishery-independent surveys (FIS) conducted cooperatively by researchers and fishers. The FIS assessed both the spatial (m to km) and temporal (months to years) dynamics of the fishery and enabled comparisons with CPUE. Concurrent size-frequency distributions provided information on the mechanisms underlying variability in resource status across the fishery. Increasing relative biomass and complexity of size structures indicated recovery of the resource from 2009, although spatial contraction of the resource also occurred. Relative biomass from FIS provides a robust fishery performance indicator that is appropriate to the scale of the fishery and has advantages over fishery-dependent CPUE of finer temporal and spatial resolution and consistent sampling efficiency. Performance indicators based on FIS provide improved understanding of the changes in resource status. Active engagement of fishers contributes to enhanced economic and environmental outcomes.

Received December 9, 2014; accepted September 3, 2015
Transport, Dam Passage, and Size Selection of Adult Atlantic Salmon in the Penobscot River, Maine
Authors: Sigourney Douglas B. , Zydlewski Joseph D. , Hughes Edward , Cox Oliver
Published: November 2015

Prior to 2012, returning adult Atlantic Salmon Salmo salar had to pass through fishways at three dams in the lower section of the Penobscot River, Maine: Veazie Dam (river kilometer [rkm] 48; removed in 2013), Great Works Dam (rkm 60; removed in 2012), and Milford Dam (rkm 62). To facilitate better passage through the lower river, a fish transport program was implemented in 2010 and 2011. Fish were captured at Veazie Dam and were either transported by truck above Milford Dam (TRKD group) or released into the head pond above Veazie Dam (run-of-the-river [ROR] group). To assess the efficacy of transport, we used PIT telemetry to compare the performance and passage of TRKD and ROR fish based on their (1) success in reaching one of the three dams upstream of Milford Dam, (2) time taken to reach an upstream dam (transit time), and (3) success in passing that upstream dam. In both years, the percentage of fish detected at upstream dams was higher for the TRKD group (82.4% in 2010; 78.6% in 2011) than for the ROR group (41.3% in 2010; 22.4% in 2011). In addition, median transit time was faster for TRKD fish (7 d in 2010; 5 d in 2011) than for ROR fish (23 d in 2010; 25 d in 2011). However, passage success through the upstream dams did not differ between the two release groups. Our analysis also revealed a strong, negative size-selective force on dam passage: larger fish were consistently less likely to successfully pass dams than smaller fish. Finally, environmental conditions also influenced passage success. Our analysis shows that the transport of adult Atlantic Salmon can be an effective means by which to increase migration success in systems where upstream passage is poor.

Received May 27, 2014; accepted September 17, 2015
Precision and Bias in Aging Northern Pike: Comparisons among Four Calcified Structures
Authors: Oele Daniel L. , Lawson Zachary J. , McIntyre Peter B.
Published: November 2015

Age estimates based on calcified structures are central to the analysis and management of fish populations. A variety of structures have been used in studies of Northern Pike Esox lucius despite limited data on whether the structures provide comparable results. We quantified precision and bias of ages estimated from cleithra, otoliths, anal fin rays, and scales of Northern Pike sampled in tributaries of Green Bay, Lake Michigan. For three independent readers, the precision (CV) of age estimates did not significantly differ among otoliths, cleithra, and anal fin rays but was significantly lower for scales than for the other structures. Similarly, partial agreement among readers was greater than 90% for ages estimated from otoliths, cleithra, and anal fin rays, whereas partial agreement was 76% for scale-based ages. We discuss the tradeoffs associated with precision and bias for each structure in the context of reader experience, fish age, and management goals. We recommend that when fish mortality is not a concern, otoliths or cleithra should be used to achieve high-precision aging of Northern Pike. For strictly nonlethal sampling scenarios, the anal fin rays of Northern Pike will yield more precise age estimates than scales.

Received January 20, 2015; accepted September 17, 2015
Differential mechanisms of Cantú syndrome–associated gain of function mutations in the ABCC9 (SUR2) subunit of the KATP channel
Authors: Cooper Paige E. , Sala-Rabanal Monica , Lee Sun Joo , Nichols Colin G.
Published: November 2015

Cantú syndrome (CS) is a rare disease characterized by congenital hypertrichosis, distinct facial features, osteochondrodysplasia, and cardiac defects. Recent genetic analysis has revealed that the majority of CS patients carry a missense mutation in ABCC9, which codes for the sulfonylurea receptor SUR2. SUR2 subunits couple with Kir6.x, inwardly rectifying potassium pore-forming subunits, to form adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, which link cell metabolism to membrane excitability in a variety of tissues including vascular smooth muscle, skeletal muscle, and the heart. The functional consequences of multiple uncharacterized CS mutations remain unclear. Here, we have focused on determining the functional consequences of three documented human CS-associated ABCC9 mutations: human P432L, A478V, and C1043Y. The mutations were engineered in the equivalent position in rat SUR2A (P429L, A475V, and C1039Y), and each was coexpressed with mouse Kir6.2. Using macroscopic rubidium (86Rb+) efflux assays, we show that KATP channels formed with P429L, A475V, or C1039Y mutants enhance KATP activity compared with wild-type (WT) channels. We used inside-out patch-clamp electrophysiology to measure channel sensitivity to ATP inhibition and to MgADP activation. For P429L and A475V mutants, sensitivity to ATP inhibition was comparable to WT channels, but activation by MgADP was significantly greater. C1039Y-dependent channels were significantly less sensitive to inhibition by ATP or by glibenclamide, but MgADP activation was comparable to WT. The results indicate that these three CS mutations all lead to overactive KATP channels, but at least two mechanisms underlie the observed gain of function: decreased ATP inhibition and enhanced MgADP activation.
Force supplementary comparison
Authors: Tegtmeier F L , Tsiporenko A
Published: November 2015

The intercomparison in the 100 kN range is organised by the pilot laboratory PTB. The intercomparison is carried out in 8 force steps: 10 kN, 14 kN, 16 kN, 20 kN, 50 kN, 60 kN, 80 kN and 100 kN.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
The origin of the X-ray-emitting object moving away from PSR B1259–63
Authors: Barkov Maxim V. , Bosch-Ramon Valentí
Published: November 2015

A mysterious X-ray-emitting object has been detected moving away from the high-mass gamma-ray binary PSR B1259–63, which contains a non-accreting pulsar and a Be star whose winds collide forming a complex interaction structure. Given the strong eccentricity of this binary, the interaction structure should be strongly anisotropic, which together with the complex evolution of the shocked winds, could explain the origin of the observed moving X-ray feature. We propose here that a fast outflow made of a pulsar–stellar wind mixture is always present moving away from the binary in the apastron direction, with the injection of stellar wind occurring at orbital phases close to periastron passage. This outflow periodically loaded with stellar wind would move with a high speed, and likely host non-thermal activity due to shocks, on scales similar to those of the observed moving X-ray object. Such an outflow is thus a very good candidate to explain this X-ray feature. This, if confirmed, would imply pulsar-to-stellar wind thrust ratios of ∼0.1, and the presence of a jet-like structure on the larger scales, up to its termination in the interstellar medium.
Characterization of Pseudomonas aeruginosa phage KPP21 belonging to family Podoviridae genus N4‐like viruses isolated in Japan
Authors: Shigehisa Ryu , Uchiyama Jumpei , Kato Shin‐ichiro , Takemura‐Uchiyama Iyo , Yamaguchi Kotoe , Miyata Reina , Ujihara Takako , Sakaguchi Yoshihiko , Okamoto Noriaki , Shimakura Hidekatsu , Daibata Masanori , Sakaguchi Masahiro , Matsuzaki Shigenobu
Published: November 2015

Bacteriophages (phages) belonging to the family Podoviridae genus N4‐like viruses have been used as therapeutic agent in phage therapy against Pseudomonas aeruginosa infections. P. aeruginosa phage KPP21 was isolated in Japan, and phylogenetically investigated the phages belonging to this viral genus. Morphological and genetic analyses confirmed that phage KPP21 belongs to the family Podoviridae genus N4‐like viruses. Moreover, phylogenetic analyses based on putative DNA polymerase and major virion protein showed that P. aeruginosa phages belonging to the genus N4‐like viruses are separated into two lineages and that phage KPP21 is in the same clade as phage LUZ7.
Do sunbirds use taste to decide how much to drink?
Authors: Bailey Ida E. , Nicolson Susan W.
Published: November 2015

Nectarivorous birds typically consume smaller meals of more concentrated than of less concentrated sugar solutions. It is not clear, however, whether they use taste to decide how much to consume or whether they base this decision on post‐ingestive feedback.

Taste, a cue to nectar concentration, is available to nectarivores during ingestion whereas post‐ingestive information about resource quality becomes available only after a meal. When conditions are variable, we would expect nectarivorous birds to base their decisions on how much to consume on taste, as post‐ingestive feedback from previous meals would not be a reliable cue to current resource quality.

Here, we tested whether white‐bellied sunbirds (Cinnyris talatala), foraging from an array of artificial flowers, use taste to decide how much to consume per meal when nectar concentration is highly variable: they did not. Instead, how much they chose to consume per meal appeared to depend on the energy intake at the previous meal, that is how hungry they were.

Our birds did, however, appear to use taste to decide how much to consume per flower visited within a meal. Unexpectedly, some individuals preferred to consume more from flowers with lower concentration rewards and some preferred to do the opposite.

We draw attention to the fact that many studies perhaps misleadingly claim that birds use sweet taste to inform their foraging decisions, as they analyse mean data for multiple meals over which post‐ingestive feedback will have become available rather than data for individual meals when only sensory information is available.

We discuss how conflicting foraging rules could explain why sunbirds do not use sweet taste to inform their meal size decisions.
Warming can enhance invasion success through asymmetries in energetic performance
Authors: Penk Marcin R. , Jeschke Jonathan M. , Minchin Dan , Donohue Ian
Published: November 2015

Both climate warming and biological invasions are prominent drivers of global environmental change and it is important to determine how they interact. However, beyond tolerance and reproductive thresholds, little is known about temperature dependence of invaders’ performance, particularly in the light of competitive attributes of functionally similar native species.

We used experimentally derived energy budgets and field temperature data to determine whether anticipated warming will asymmetrically affect the energy budgets of the globally invasive Ponto‐Caspian mysid crustacean Hemimysis anomala and a functionally similar native competitor (Mysis salemaai) whose range is currently being invaded.

In contrast to M. salemaai, which maintains a constant feeding rate with temperature leading to diminishing energy assimilation, we found that H. anomala increases its feeding rate with temperature in parallel with growing metabolic demand. This enabled the invader to maintain high energy assimilation rates, conferring substantially higher scope for growth compared to the native analogue at spring‐to‐autumn temperatures. Anticipated warming will likely exacerbate this energetic asymmetry and remove the winter overlap, which, given the seasonal limitation of mutually preferred prey, appears to underpin coexistence of the two species.

These results indicate that temperature‐dependent asymmetries in scope for growth between invaders and native analogues comprise an important mechanism determining invasion success under warming climates. They also highlight the importance of considering relevant spectra of ecological contexts in predicting successful invaders and their impacts under warming scenarios.
Ecology and physiology of anaerobic ammonium oxidizing bacteria
Authors: Oshiki Mamoru , Satoh Hisashi , Okabe Satoshi
Published: November 2015

Anaerobic ammonium oxidation (anammox) is a microbial process in which NH4+ is oxidized to N2 gas with NO2− as an electron acceptor. The anammox process is mediated by bacterial members affiliated with the phylum Planctomycetes, which are ubiquitously detected from anoxic natural and man‐made ecosystems and a key player in the global nitrogen cycle. In the past two decades, phylogenetically different anammox bacteria have been recognized in natural and synthetic ecosystems (i.e. ‘Candidatus Kuenenia’, ‘Candidatus Brocadia’, ‘Candidatus Jettenia’, ‘Candidatus Anammoxoglobus’ and ‘Candidatus Scalindua’ genera), and the geographic distributions of these anammox bacteria indicate that they have genus‐specific or species‐specific habitats. Recently, we revealed the physiological characteristics of ‘Ca. Jettenia’ in addition to ‘Ca. Kuenenia’, ‘Ca. Brocadia’ and ‘Ca. Scalindua’, and, as a result, it is possible to compare the physiological characteristics of the anammox bacteria and discuss their niche partitioning. Therefore, we summarize the current knowledge of anammox bacterial ecology and physiology in this review to assess the potential ecological niche partitioning of anammox bacteria in natural and synthetic ecosystems.