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Chromium complexes bearing non-innocent iminopyridine ligands were investigated as precatalysts for the polymerization of ethylene using different aluminum cocatalysts and Lewis base NEt3 as additive. Beyond confirming the key role of the chromium to ligand synergy in accessing the active complex, other factors that play a crucial role are (i) the nature of the aluminum activator that influences the ion pair generated, (ii) the presence of the additive that boosts the synthesis of UHMWPE with narrow and unimodal molecular weight distribution even at 40 °C, and (iii) the polymerization temperature that affects the polymerization catalysis and the polymer molecular weight. UV-vis-NIR and Fourier transform infrared (FT-IR) spectroscopic techniques have been applied to inspect the activation process and to understand the mode of action by which NEt3 affects the catalytic conversion of ethylene. NEt3 interacts with the aluminum cocatalyst (rather than with the chromium complex) to form an Et3N-AlRx adduct, thus affecting the catalytic ion pair.

The replacement of native dry forests by commercial (exotic) tree plantations could generate changes in rainfall partitioning, which further affects the water cycle. In this study, we determined (i) the rainfall partitioning into interception, throughfall and stemflow, (ii) the role of rainfall event size on rainfall partitioning, (iii) the pH of water channelized as throughfall and stemflow, and (iv) the runoff in Lithraea molleoides (a native species) and Pinus elliottii (an exotic species) stands in the dry Chaco mountain forests, central Argentina. On average, interception, throughfall and stemflow accounted for 19.3%, 79.5% and 1.2% of the gross rainfall in L. molleoides stand, and 32.6%, 66.7% and 0.7% of the gross rainfall in P. elliottii stand, respectively. Amounts of interception, throughfall and stemflow presented positive linear relationships with the increment of rainfall event size for both tree species (P

Patterns of genetic structure in highly mobile marine vertebrates may be accompanied by phenotypic variation. Most studies in marine turtles focused on population genetic structure have been performed at rookeries. We studied whether genetic and morphological variation of the endangered green turtle (Chelonia mydas) is consistent geographically, focusing on foraging grounds. An association between population genetic structure and body shape variation at broad (inter-lineage) and fine (foraging grounds) scales was predicted and analysed using mitochondrial DNA and geometric morphometrics. Although genetic and phenotypic differentiation patterns were congruent between lineages, no fine-scale association was found, suggesting adaptive divergence. Connectivity among Pacific foraging grounds found here suggests that temperatures of ocean surface currents may influence the genetic structure of C. mydas on a broad scale. Our results suggest that vicariance, dispersal, life-history traits and ecological conditions operating in foraging grounds have shaped the intraspecific morphology and genetic diversity of this species. Considering a range of geographic and temporal scales is useful when management strategies are required for cosmopolitan species. Integrating morphological and genetic tools at different spatial scales, conservation management is proposed based on protection of neutral and adaptive diversity. This approach opens new questions and challenges, especially regarding conservation genetics in cosmopolitan species.

The activation of MgCl2 is an essential step for preparing performant Ziegler-Natta (ZN) catalysts for olefin polymerization, either by mechanical grinding of pristine MgCl2 or by chemical conversion of a precursor. Depending on the adopted activation process, different nanostructures are obtained in terms of disorder and morphology, which in turn influence the overall catalytic performance. In this work, we focused on the morphology of δ-MgCl2 nanoparticles (i.e. the relative extension of the exposed surfaces), by investigating with vibrational spectroscopies a series of mechanically and chemically activated MgCl2 samples, and by building up a comprehensive set of model structures (both ordered and disordered) and relative surfaces in order to highlight nanosizing effects and achieve an accurate description of MgCl2 particles at an atomistic level. We found that both mechanical and chemical activation promote the expression of MgCl2 surfaces exposing strongly acidic Mg2+ sites, which are those mostly involved in the catalysis, together with an increase of inter-surfaces edges, which have been recently considered as the main responsible for the ZN catalysts stereo-selectivity.

In the field of Ziegler–Natta catalysis for olefin polymerization, carbon monoxide (CO) is used in the industrial practice to quench the reaction when it proceeds too fast, approaching critical levels for the plant safety. The quenching effect is explained as due to the reversible coordination of CO to the titanium active sites, but no direct evidence has been ever reported. In this work, we designed a series of experiments to monitor CO adsorption at variable temperatures on a model Ziegler–Natta catalyst by means of FT-IR spectroscopy. For the first time, we have been able to spectroscopically detect CO coordinated to alkylated Ti3+ sites and the Ti–acyl species formed upon the subsequent insertion of CO into the Ti3+–alkyl bond, both in the absence and in the presence of the olefin monomer. In perspective, this has important implications for the characterization of the active sites in industrial Ziegler–Natta catalysts, even under working conditions.

The activation of MgCl2 is an essential step for preparing performant Ziegler-Natta catalysts (ZNCs), but the structural characterization of the so formed δ-MgCl2 has been left behind due to its complicated disorder. In the current study, synchrotron X-ray total scattering is applied for the structure analysis of δ-MgCl2. Complementary use of powder X-ray diffraction (PXRD) and pair distribution function (PDF) enabled determining the type and extent of disorder for a series of mechanically and chemically activated δ-MgCl2 samples. Moreover, their combination with molecular simulation successfully derived consistent nanoparticle models, where the conventional interpretation of disorderedly stacked nanoplates was justified in a cross-validated manner.

Green turtles Chelonia mydas are listed as Endangered on the IUCN Red List, yet in the South Pacific few conservation-relevant data are available for the species, especially relating to foraging and habitat use. Here, in situ observations and stable isotope analysis (δ13C and δ15N) were used to evaluate green turtle diet and recruitment patterns at Yadua Island and Makogai Island, Fiji. Juvenile green turtles (N = 110) were hand-captured, measured, and sampled. Stable isotope analysis was performed on skin samples and on putative prey items. ‘Resident’ turtles versus ‘recent recruits’ were classified based on their bulk skin tissue isotope values, which were compared with stable isotope values of local prey items and analyzed via cluster analysis. Green turtle diet composition was estimated using MixSIAR, a Bayesian mixing model. Recent recruits were characterized by ‘low δ13C/high δ15N’ values and ranged in curved carapace length (CCL) from 25.5 to 60.0 cm (mean ± SD = 48.5 ± 5.7 cm). Recruitment mostly occurred in summer. Green turtles identified as ‘residents’ had CCLs ranging from 43.5 to 89.0 cm (mean ± SD = 57.4 ± 9.0 cm) and were characterized by ‘high δ13C/low δ15N’ values; mixing model results indicate they fed primarily on invertebrates (40%), fishes (31%), and marine plants (29%). This study confirms the value of seagrass pastures as both an essential habitat and a primary food source for green turtles, and can serve as a baseline for evaluations of natural and anthropogenic changes in local green turtle aggregations.

In contrast to most of the other olefin polymerization catalysts, the Cr/SiO2 Phillips catalyst does not need any activator to develop its activity. However, it is known that the addition of a small amount of metal-alkyls has drastic effects on the catalyst performance, and it is one of the strategies adopted in industrial practice to tailor the properties of the polyethylene produced. In this work, we conducted a systematic investigation on the effect of triethylaluminum on the Cr(VI)/SiO2 catalyst, with the ultimate goal to determine the properties of the Cr sites at a molecular level and to correlate them to the properties of the obtained polyethylene. To this aim, we coupled kinetic tests, spectroscopic methods (diffuse reflectance UV–vis–near-infrared, electron paramagnetic resonance, Fourier-transform infrared spectroscopy of probe molecules), and different polymer characterization techniques. We found that, at an Al/Cr ratio of 2:1, only ca. 50% of the original Cr(VI) sites are reduced to a variety...

The all-inorganic perovskite barium zirconate, BaZrO3, is a widely used material in a range of different technological applications. However, fundamental questions surrounding the crystal structure of BaZrO3, especially in regard to its ground-state structure, remain. While diffraction techniques indicate a cubic structure all the way down to T = 0 K, several first-principles phonon calculation studies based on density functional theory indicate an imaginary (unstable) phonon mode due to the appearance of an antiferrodistortive transition associated with rigid rotations of ZrO6 octahedra. The first-principles calculations are highly sensitive to the choice of exchange-correlation functional and, using six well-established functional approximations, we show that a correct description about the ground-state structure of BaZrO3 requires the use of hybrid functionals. The ground-state structure of BaZrO3 is found to be cubic, which is corroborated by experimental results obtained from neutron powder diffraction, inelastic neutron scattering, and neutron Compton scattering experiments.

Extensive quasielastic neutron scattering measurements have been used to directly observe oxide ion dynamics on the nanosecond time scale in bismuth vanadate with formula Bi0.913V0.087O1.587, which exhibits remarkable oxide ion conductivity at low temperatures. This is the longest time scale neutron scattering study of any fluorite-type solid electrolyte, and it represents only the second case of oxide ion dynamics in any material observed on a nanosecond time scale by quasielastic neutron scattering. Ab initio molecular dynamics simulations reveal two mechanisms that contribute to the oxide ion dynamics in the material: a slower diffusion process through the Bi-O sublattice and a faster process which corresponds to more localized dynamics of the oxide ions within the VO x coordination spheres. The length of the trajectories simulated and the validation of the simulations by neutron scattering experiments provide for the first time a quantitative insight into the relative contributions of the two processes to the oxide ion conduction in this exceptional solid electrolyte, which can be used to derive design principles for the preparation of related oxide ion conductors with even better properties.

The time-tested indigenous fishing knowledge (IFK) of the Pacific Islands is seriously threatened due to the commercialization of fishing, the breakdown of traditional communal leadership and oral knowledge transmission systems, modern education and the movement of the younger generations to urban areas for work and/or study. As a consequence, IFK, which has been orally transmitted for generations, has been lost, not learned by the current generation, or remains undocumented. This desktop study focuses on the critical need for conserving and including IFK as a basis for assessing the conservation status of ecologically and culturally important keystone fisheries species as a basis for planning and site-specific management of marine and freshwater fisheries in Fiji and the Pacific Islands. The study reviews information on IFK from Fiji and elsewhere in the small oceanic islands of the Pacific as a basis for the conservation, documentation and intergenerational transfer of this knowledge as the foundation for sustainable fisheries management in these nations. The study spanned over documents from the last two and a half centuries. The results include a review of the nature and conservation status of IFK and the conservation status of species considered to be of particular ecological and cultural importance, reasons for the loss of species/taxa and associated knowledge and practices, and actions that need to be taken to address this loss. Moreover, it also highlights ways to counter the erosion of the threatened IFK so that the future generations can have access to it.

We report an inelastic neutron scattering study on the magnetic excitations of ${\mathrm{Pr}}_{2}{\mathrm{NiO}}_{4+\ensuremath{\delta}}$ ($\ensuremath{\delta}\ensuremath{\sim}0.24\ifmmode\pm\else\textpm\fi{}0.01$) at $T=10$ K. Spin stripe ordering becomes pronounced below $\ensuremath{\sim}220$ K with an incommensurability $\ensuremath{\epsilon}\ensuremath{\approx}0.346$, and a strong influence of interstitial oxygen is identified on establishing a long-range spin stripe ordering. Apart from the Goldstone modes emerging from the magnetic satellites (${\mathbf{q}}_{m}$), multiple homologous modes are observed along the spin stripe modulation separated by $\mathrm{\ensuremath{\Delta}}{\mathbf{q}}_{m}\ensuremath{\approx}0.076$ in reciprocal lattice units, which is interpreted by the internal periodicity of the long-range ordered discommensurated spin stripes.

Author(s): Fornaroli, Riccardo; Agostini, Alessandra; Arnaud, Elena; Berselli, Alberto; Bettoni, Eugenia; Boggero, Angela; Borlandelli, Cristina; Cadrobbi, Giuseppi; Cason, Manuela; Castelli, Luciano; Cerea, Silvia; Contardi, Laura; Costa, Sara; Costaraoss, Silvia; Dallafior, Valentina; Dal Mas, Alessandro; Elvio, Francesco; Fioravanti, Marco; Fortino, Davide; Franceschini, Silvia; Fravezzi, Laura; Fuganti, Alessia; Galbiati, Matteo; Galimberti, Filippo; Genoni, Pietro; Gerbaz, Daniela; Lea, Alessia; Lucchini, Daniela; Manzieri, Anna Maria; Marchesi, Manuela; Monauni, Catia; Montanari, Paola; Morchio, Federica; Piovano, Silvia; Pizzochero, Natale; Raviola, Mara; Richieri, Filippo; Roatta, Valeria; Rocca, Daniela; Sarzilla, Attilio; Siciliano, Ornella; Testa, Paola; Tonna, Davide; Tumminelli, Marzia Enza; Turco, Franca; Vicquery, Luciana; Laini, Alex | Abstract: Rivers serve many societal functions and are one of the most intensively human influenced ecosystems worldwide, and, due to their importance, are included under the monitoring programs of the Water Framework Directive across Europe. Macroinvertebrates play an important role when monitoring running waters for the assessment of their environmental quality due to their reliability as bioindicators and utility in long-term studies. Macroinvertebrates do not constitute a systematic unit but they are formed by a set of different taxa, grouped according to taxonomic ranks, size and habitat preferences. They represent the base of the aquatic food chain, serving as a food source for amphibians, birds, reptiles, fish and humans, and contributing in the organic matter processing. Despite the large amount of data collected on Italian river macroinvertebrates and the increased interest in the study of this group, only few data are available for research scientist and managers. In this paper, we collected and homogenized knowledge on the presence, distribution and abundances of macroinvertebrates taxa inhabiting the River Po catchment (Northern Italy) in the last decade. The data set includes 130,727 records collected between 2007 and 2018 including 143 taxa of macroinvertebrates, mostly identified at family rank level. Moreover, the data set provides information on the geographic distribution of these families and their abundance by sub-catchment, altitude, meso- and micro-habitat.

Several spectroscopic techniques have been applied in a concerted way to investigate the local structure and the function of the chromium sites in a series of Cr[CH(SiMe3)2]3/SiO2 catalysts for ethene polymerization that differ in chromium loading and to correlate them with the microstructure of the produced polyethylene (PE). According to previous studies, the density of the produced PE is proportional to the Cr loading: the higher the Cr loading, the lower the PE density, because of an increase in the content of short-chain branching. Here, the nature of the branches and their enchainment in the polymer have been further investigated to determine the different properties of the produced polymers, and the differences detected have been traced back by spectroscopic analysis to the presence of two different types of Cr sites working in tandem: monografted SiO Cr[CH(SiMe3)2]2 species that are responsible for ethene oligomerization, and bis-grafted ( SiO )2CrCH(SiMe3)2 species that account for ethene homo- and co-polymerization. The relative abundance of the two species depends on the chromium loading. Moreover, we have also found that carbon monoxide selectively poisons the sites responsible for ethene oligomerization, indicating a possible strategy for the fine regulation of the properties of the produced PE.

Extreme mass-ratio inspirals~(EMRIs) detectable by the Laser Inteferometric Space Antenna~(LISA) are unique probes of astrophysics and fundamental physics. Parameter estimation for these sources is challenging, especially because the waveforms are long, complicated, known only numerically, and slow to compute in the most relevant regime, where the dynamics is relativistic. We perform a time-consuming Fisher-matrix error analysis of the EMRI parameters using fully-relativistic numerical waveforms to leading order in an adiabatic expansion on a Kerr background, taking into account the motion of the LISA constellation, higher harmonics, and also including the leading correction from the spin of the secondary in the post-adiabatic approximation. We pay particular attention to the convergence of the numerical derivatives in the Fisher matrix and to the numerical stability of the covariance matrix, which for some systems requires computing the numerical waveforms with approximately $90$-digit precision. Our analysis confirms previous results (obtained with approximated but much more computationally efficient waveforms) for the measurement errors on the binary's parameters. We also show that the inclusion of higher harmonics improves the errors on the luminosity distance and on the orbital angular momentum angles by one order and two orders of magnitude, respectively, which might be useful to identify the environments where EMRIs live. We particularly focus on the measurability of the spin of the secondary, confirming that it cannot be measured with sufficient accuracy. However, due to correlations, its inclusion in the waveform model can deteriorate the accuracy on the measurements of other parameters by orders of magnitude, unless a physically-motivated prior on the secondary spin is imposed., 11 pages + appendices and references; 4 tables. Supplemental Mathematica notebooks available at https://web.uniroma1.it/gmunu/resources

We have successfully grown centimeter-sized layered $$\textit{R}\mathrm{SrNiO}_{4}$$ R SrNiO 4 single crystals under high oxygen pressures of 120–150 bar by the floating zone technique. This enabled us to perform neutron scattering experiments where we observe close to quarter-integer magnetic peaks below $$\sim 77~\mathrm{K}$$ ∼ 77 K that are accompanied by steep upwards dispersing spin excitations. Within the high-frequency Ni–O bond stretching phonon dispersion, a softening at the propagation vector for a checkerboard modulation can be observed. We were able to simulate the magnetic excitation spectra using a model that includes two essential ingredients, namely checkerboard charge disproportionation and nano phase separation. The results thus suggest that charge disproportionation is preferred instead of a Jahn–Teller distortion even for this layered $$\mathrm{Ni}^{3+}$$ Ni 3 + system.

A combination of synchrotron X-ray total scattering and molecular simulation is a powerful approach for reliable determination of the structure of &delta, MgCl2 as an indispensable component of heterogeneous Ziegler&ndash, Natta catalysts. Here, the same approach is applied to mechanically activated MgCl2. Four types of mechanically activated MgCl2 samples are prepared using ball-milling in the absence and presence of different donors. The development of structural disorder along the grinding time is compared. It was found that the presence of donors accelerates the formation of &delta, MgCl2 in an early stage of grinding, while elongated grinding eventually results in &delta, MgCl2 with similar extents of structural disorder in the absence and presence of different donors. The FT-IR investigation consistently verified the morphological similarity between the firmly ground samples. Thus, the structure of &delta, MgCl2 is likely governed by mechanical energy when sufficiently ground.

The magnon diffusion length (MDL) is understood to play a major role in the thickness dependence of spin Seebeck effect (SSE) voltages in ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}/\mathrm{Pt}$ thin films. Here we extract the MDL in an ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ single crystal using inelastic neutron scattering (INS) and in ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}/\mathrm{Pt}$ thin films using accurate heat flux SSE and static magnetization measurements. The INS MDLs were $34\ifmmode\pm\else\textpm\fi{}8\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $300\phantom{\rule{4pt}{0ex}}\mathrm{K}$ and $27\ifmmode\pm\else\textpm\fi{}6\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $50\phantom{\rule{4pt}{0ex}}\mathrm{K}$. The SSE MDLs decreased with temperature ($19\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $300\phantom{\rule{4pt}{0ex}}\mathrm{K}$ and $13\ifmmode\pm\else\textpm\fi{}4\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $50\phantom{\rule{4pt}{0ex}}\mathrm{K}$), but were markedly smaller. Whilst the bulk MDL is expected to be an upper limit of the MDL in thin films, we show that the film magnetization must be considered to obtain MDLs from SSE measurements. This study highlights the importance of disentangling the role of various effects in SSE measurements which is crucial in increasing the efficiencies of thermomagnetic energy harvesting devices.

THORONDOR is a data treatment software with a graphical user interface (GUI) accessible via the browser-based Jupyter notebook framework. It aims to provide an interactive and user-friendly tool for the analysis of NEXAFS spectra collected during in situ experiments. The program allows on-the-fly representation and quick correction of large datasets from single or multiple experiments. In particular, it provides the possibility to align in energy several spectral profiles on the basis of user-defined references. Various techniques to calculate background subtraction and signal normalization have been made available. In this context, an innovation of this GUI involves the usage of a slider-based approach that provides the ability to instantly manipulate and visualize processed data for the user. Finally, the program is characterized by an advanced fitting toolbox based on the lmfit package. It offers a large selection of fitting routines as well as different peak distributions and empirical ionization potential step edges, which can be used for the fit of the NEXAFS rising-edge peaks. Statistical parameters describing the goodness of a fit such as χ2 or the R-factor together with the parameter uncertainty distributions and the related correlations can be extracted for each chosen model.

Aquatic systems receive a wide range of pharmaceuticals that may have adverse impacts on aquatic wildlife. Among these pharmaceuticals, antihistamines are commonly found, and these substances have the potential to influence the physiology of aquatic invertebrates. Previous studies have focused on how antihistamines may affect behaviours of aquatic invertebrates, but these studies probably do not capture the full consequences of antihistamine exposure, as traditional recording techniques do not capture important animal movements occurring at the scale of milliseconds, such as prey escape responses. In this study, we investigated if antihistamine exposure can impact escape responses in aquatic insect, by exposing damselfly (Coenagrion hastulatum) larvae to two environmentally relevant concentrations (0.1 and 1 μg L

Inelastic neutron scattering has been used to study the in-plane Cu-O bond-stretching mode in oxygen-doped ${\mathrm{La}}_{1.94}{\mathrm{Sr}}_{0.06}{\mathrm{CuO}}_{4.035}$ $({T}_{c}=38\phantom{\rule{0.28em}{0ex}}\text{K})$ and ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4+\ensuremath{\delta}}$ $({T}_{c}=43\phantom{\rule{0.28em}{0ex}}\text{K})$. Similar to results from optimally doped ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}{\mathrm{CuO}}_{4}$ $({T}_{c}=35\phantom{\rule{0.28em}{0ex}}\text{K})$, we observe anomalous features in the dispersion of this half-breathing mode in the form of a softening halfway through the Brillouin zone. Considering the differences in electronic structure and local environment between the oxygen- and strontium-doped compounds with similar ${T}_{\text{c}}$, we rule out a connection between the phonon anomaly and structural instabilities related to the specific dopant type. We interpret the phonon anomaly as a signature of correlated charge fluctuations ubiquitous in optimally doped superconductors.

An outstanding prediction of general relativity is the fact that the angular momentum $S$ of an isolated black hole with mass $\mu$ is limited by the Kerr bound, $S\leq G\mu^2/c$. Testing this cornerstone is challenging due to the difficulty in modelling spinning compact objects that violate this bound. We argue that precise, model-independent tests can be achieved by measuring gravitational waves from an extreme mass ratio inspiral around a supermassive object, one of the main targets of the future LISA mission. In the extreme mass ratio limit, the dynamics of the small compact object depends only on its multipole moments, which are free parameters. At variance with the comparable-mass case, accurate waveforms are valid also when the spin of the small object greatly exceeds the Kerr bound. By computing the orbital dephasing and the gravitational-wave signal emitted by a spinning point particle in circular, nonprecessing, equatorial motion around a Kerr black hole, we estimate that LISA will be able to measure the spin of the small compact object at the level of $10\%$. Together with mass measurements, this will allow for theory-agnostic, unprecedented constraints on string-theory inspired objects such as "superspinars", almost in their entire parameter space., Comment: Improvements in response to referee reports. Typos corrected. Data and code available at https://web.uniroma1.it/gmunu

Herein we report on two photoinduced reactions occurring at the surface of the CrVI/SiO2 Phillips catalyst. The first is the photoreduction of CrVI/SiO2 in CO at room temperature, that leads to the reduction of a fraction of the CrVI sites to CrIV(═O) intermediates and then to CrII. With respect to the thermal reduction of CrVI/SiO2 in CO, the relative amount of highly uncoordinated CrII sites is larger, suggesting that the relaxation of the CrII sites at the silica surface strongly depends on the temperature at which they are formed. The second is the photoinduced ethylene polymerization on CrVI/SiO2 at room temperature that is reported here for the first time. We demonstrate that UV–vis light has the potential to trigger the reduction of chromates by ethylene and the successive ethylene polymerization. Diffuse reflectance (DR) UV–vis and FT-IR spectroscopies allowed us to identify the nature of the Cr sites involved in the polymerization (i.e., 6-fold coordinated CrII) and of the oxidized byproducts rem...

Al-alkyls are often used in the industrial practice for modifying the Phillips catalysts for polyethylene production: they are not necessary to develop the activity, but they have relevant effects on the catalysis, decreasing the induction time, promoting the in situ branching, and enhancing the H2 sensitivity for the molecular weight regulation. Herein we investigate the effect of diethylaluminum ethoxide (DEALE) on Cr(II)/SiO2 (in a stoichiometric amount of Al:Cr = 2:1), focusing the attention on the modification of the Cr(II) sites at a molecular level. Diffuse reflectance UV–Vis and FT-IR spectroscopies, applied in the presence of CO and CD3CN as molecular probes, unequivocally demonstrate that: (1) DEALE modifies only a fraction of the Cr(II) sites (ca. 30%) even if dosed in excess with respect to the Cr sites; (2) DEALE reacts with the silica surface, forming Al-grafted species which are at least partially in interaction with the Cr(II) sites and hence act as ancillary ligands; (3) the modified Cr(II) sites are more acidic and likely mono-grafted to the silica surface; the presence of Al-grafted species nearby is essential for their stabilization. Finally, kinetic experiments indicate that the modified Cr(II) sites are ca. 60 times faster in inserting ethylene than the unmodified Cr(II) sites. The intrinsic higher activity of the modified Cr(II) sites is a consequence not only of their molecular structure, but of the whole series of effects listed above.

In this work, we have addressed the question of the location of electron donors (we chose ethylbenzoate, EB, for practical reasons) on the surface of MgCl2-supported Ziegler–Natta catalysts by syne...

Introduction of Bi(III) into apatite-type germanate oxide ion conductors can improve the conductivity by up to two orders of magnitude. To account for these experimental findings, we have carried out the first ab initio molecular dynamics simulations study of the conduction mechanisms in lone pair-containing apatite-type oxide ion conductors. These calculations were performed on the series La10−xBixGe6O27 (x = 0, 2, 4) and were supported by neutron scattering experiments. We observe four types of oxide ion exchange mechanisms and describe the effects that the introduction of lone-pair cations has on the O2− migration pathways and on the overall conductivity.

The material class of rare earth nickelates with high Ni$^{3+}$ oxidation state is generating continued interest due to the occurrence of a metal-insulator transition with charge order and the appearance of non-collinear magnetic phases within this insulating regime. The recent theoretical prediction for superconductivity in LaNiO$_3$ thin films has also triggered intensive research efforts. LaNiO$_3$ seems to be the only rare earth nickelate that stays metallic and paramagnetic down to lowest temperatures. So far, centimetre-sized impurity-free single crystal growth has not been reported for the rare earth nickelates material class since elevated oxygen pressures are required for their synthesis. Here, we report on the successful growth of centimetre-sized LaNiO$_3$ single crystals by the floating zone technique at oxygen pressures of up to 150 bar. Our crystals are essentially free from Ni$^{2+}$ impurities and exhibit metallic properties together with an unexpected but clear antiferromagnetic transition., Nature Communications 9 (1), 43, S. 1 - 7 (2018)

We consider the $K$-User Multiple-Input-Single-Output (MISO) Broadcast Channel (BC) where the transmitter, equipped with $M$ antennas, serves $K$ users, with $K \leq M$. The transmitter has access to a partial channel state information of the users. This is modelled by letting the variance of the Channel State Information at the Transmitter (CSIT) error of user $i$ scale as $O(P^{-\alpha_i}$) for the Signal-to-Noise Ratio (SNR) $P$ and some constant $\alpha_i \geq 0$. In this work we derive the optimal Degrees-of-Freedom (DoF) region in such setting and we show that Rate-Splitting (RS) is the key scheme to achieve such a region., Comment: It is accepted for publications on IEEE Communications Letters

Fe x Mn1−x S belongs to the group of strong electron correlations compounds MnO. We present here experimental results for the antiferromagnetic iron–manganese sulfide system, based on X-ray and neutron diffraction studies. The neutron diffraction investigations were carried out at ambient conditions and at hydrostatic pressures up to 4.2 GPa in the temperature range from 65 to 300 K. Our results indicate that the Neel temperature of α-MnS increases up to room temperature by applying chemical (x Fe) or weak hydrostatic pressure P. In Fe0.27Mn0.73S, the Neel temperature increases from 205(2) K (P = 0 GPa) to 280(2) K (P = 4.2 GPa) and the magnetization at 100 K decreases by a factor of 2.5 when the hydrostatic pressure increases from 0 to 4.2 GPa.

Operando-sensitive spectroscopic techniques were employed for investigating the changes in the molecular structure of the Cr sites in the CrVI/SiO2 Phillips catalyst during ethylene polymerization. Practically, the most arduous barrier to be overcome was the separation of the chromates reduction carried out by ethylene from the subsequent polymerization. By carefully tuning the experimental parameters we succeeded in observing these two events separately. We found that the sites involved in ethylene polymerization are mainly divalent Cr ions in a 6-fold coordination, in interaction with the oxygenated byproduct (mostly methylformate, generated from the disproportionation of two formaldehyde molecules). Unreduced CrVI species are also present during ethylene polymerization as well as reduced Cr species (either CrII or CrIII) acting as spectators. Our results challenge the old vision of “naked” chromium species (i.e., low coordinated) as the active sites and attribute a fundamental role to external (and fle...

Background and Aims The symmetry of venation patterning in leaves is highly conserved within a plant species. Auxins are involved in this process and also in xylem vasculature development. Studying transgenic Arabidopsis plants ectopically expressing the sunflower transcription factor HaHB4, it was observed that there was a significant lateral-vein asymmetry in leaves and in xylem formation compared to wild type plants. To unravel the molecular mechanisms behind this phenotype, genes differentially expressed in these plants and related to auxin influx were investigated. Methods Candidate genes responsible for the observed phenotypes were selected using a co-expression analysis. Single and multiple mutants in auxin influx carriers were characterized by morphological, physiological and molecular techniques. The analysis was further complemented by restoring the wild type (WT) phenotype by mutant complementation studies and using transgenic soybean plants ectopically expressing HaHB4. Key Results LAX2, down-regulated in HaHB4 transgenic plants, was bioinformatically chosen as a candidate gene. The quadruple mutant aux1 lax1 lax2 lax3 and the single mutants, except lax1, presented an enhanced asymmetry in venation patterning. Additionally, the xylem vasculature of the lax2 mutant and the HaHB4-expressing plants differed from the WT vasculature, including increased xylem length and number of xylem cell rows. Complementation of the lax2 mutant with the LAX2 gene restored both lateral-vein symmetry and xylem/stem area ratio in the stem, showing that auxin homeostasis is required to achieve normal vascular development. Interestingly, soybean plants ectopically expressing HaHB4 also showed an increased asymmetry in the venation patterning, accompanied by the repression of several GmLAX genes. Conclusions Auxin influx carriers have a significant role in leaf venation pattering in leaves and, in particular, LAX2 is required for normal xylem development, probablt controlling auxin homeostasis. Fil: Moreno Piovano, Guillermo Samuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Moreno, Javier Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Cabello, Julieta Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Arce, Agustín Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Otegui, Maria Elena. Universidad de Buenos Aires; Argentina Fil: Chan, Raquel Lia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

Reservoirs hold a detailed record of the changes in the input of sediments and nutrients over decades to centuries. Paleolimnological multi-proxy analysis makes it possible to reconstruct baseline conditions to infer early evidence of environmental change. Our study aims to reconstruct historical human impacts derived from urban development on the San Roque reservoir (Cordoba, Argentina) related to the centennial dynamics of sedimentary and eutrophication processes. A paleolimnological record, dated by 210Pb and 137Cs, made it possible to identify two stages during the environmental evolution of the San Roque reservoir. Physical processes, such as fluvial discharge and water level variation, dominantly ruled stage 1 (Unit C) during the initial infilling of the reservoir. Nutrient load and eutrophication processes controlled stage 2 (Units B and A). Stage 1 (77-55 cm; AD 1921 to 1965) occurred before and after the second dam was built and while the level of water increased by ≈ + 8 m; it displayed a high variation in mean grain size and maximum values of magnetic susceptibility. Stage 2 (AD 1965–2017) records a new reservoir base level and the maintenance of high water levels and comparatively more stable conditions. Regarding the eutrophication process throughout stage 2, three sub-stages were defined: a) Sub-stage I (AD 1965–1985) is a period of incipient eutrophication; b) Sub-stage II (AD 1985–2005) is an interval of increase of eutrophication as shown by the increase in several organic proxies related to the abundance of phytoplankton. Echinenone, zeaxanthin and myxoxanthophyll indicate that cyanobacteria increased concentration by three-to four-fold in comparison with the previous sub-stage. c) Sub-stage III (AD 2005–2017) shows the transition to a hypereutrophic state. Diatomea (fuco and diato), dinophyceae (diadino), chlorophyta (lut) and cryptophyta (allo) groups show a comparatively higher contribution. Our results mostly highlight that during the last century the main drivers of changes in the environmental state of the San Roque reservoir were trophic, fluvial and hydrometeorological. These results might provide tools for anticipating future scenarios for water management plans under increasing anthropic pressure.

Starting from the three-dimensional setting, we derive a limit model of a thin magnetoelastic film by means of $$\varGamma $$ Γ -convergence techniques. As magnetization vectors are defined on the elastically deformed configuration, our model features both Lagrangian and Eulerian terms. This calls for qualifying admissible three-dimensional deformations of planar domains in terms of injectivity. In addition, a careful treatment of the Maxwell system in the deformed film is required.

The phytochemical study of the alcoholic extract obtained from Bipinnula fimbriata (Poepp.) I.M.Johnst., allowed to isolate three metabolites, corresponding to the butanolide kinsenoside (1) and to two dihydrostilbene derivatives, which have been assigned as 3-methoxy-5-{2-[3-methoxy-2-(3-methylbut-2-en-1-yl)-phenyl]ethyl}phenol (2) and 4-[2-(3-hydroxy-5-methoxyphenyl)ethyl]-2-(3-methylbut-2-en-1-yl)phenol, also named cannabistilbene I (3). The occurrence of these compounds is consistent with the current classification of the genus and allowed to point out some chemotaxonomic considerations.

Place: Dordrecht Publisher: Springer WOS:000555361400001; International audience; Fisheries can profoundly affect bycatch species with 'slow' life history traits. Managing bait type offers one tool to control species selectivity. Different species and sizes of marine predators have different prey, and hence bait, preferences. This preference is a function of a bait's chemical, visual, acoustic and textural characteristics and size, and for seabirds the effect on hook sink rate is also important. We conducted a global meta-analysis of existing estimates of the relative risk of capture on different pelagic longline baits. We applied a Bayesian random effects meta-analytic regression modelling approach to estimate overall expected bait-specific catch rates. For blue shark and marine turtles, there were 34% (95% HDI: 4-59%) and 60% (95% HDI: 44-76%) significantly lower relative risks of capture on forage fish bait than squid bait, respectively. Overall estimates of bait-specific relative risk were not significantly different for seven other assessed taxa. The lack of a significant overall estimate of relative capture risk for pelagic shark species combined but significant effect for blue sharks suggests there is species-specific variability in bait-specific catch risk within this group. A qualitative literature review suggests that tunas and istiophorid billfishes may have higher catch rates on squid than fish bait, which conflicts with reducing marine turtle and blue shark catch rates. The findings from this synthesis of quantitative and qualitative evidence support identifying economically viable bycatch management measures with acceptable tradeoffs when multispecies conflicts are unavoidable, and highlight research priorities for global pelagic longline fisheries.

Extreme mass-ratio inspirals detectable by the future Laser Interferometer Space Antenna provide a unique way to test general relativity and fundamental physics. Motivated by this possibility, here we study in detail the EMRI dynamics in the presence of a spinning secondary, collecting and extending various results that appeared in previous work and also providing useful intermediate steps and new relations for the first time. We present the results of a frequency-domain code that computes gravitational-wave fluxes and the adiabatic orbital evolution for the case of circular, equatorial orbits with (anti)aligned spins. The spin of the secondary starts affecting the gravitational-wave phase at the same post-adiabatic order as the leading-order self-force terms and introduces a detectable dephasing, which can be used to measure it at $5-25\%$ level, depending on individual spins. In a companion paper we discuss the implication of this effect for tests of the Kerr bound., Improvements in response to referee reports. Typos corrected. Longer companion paper of arXiv:2003.08448. Data and code available at the website https://web.uniroma1.it/gmunu

This work is focused on the determination of the most likely border morphologies in the H-terminated graphenic domains that constitute activated carbons, focusing on four different carbons and six supported-metal catalysts. Among the available characterization techniques, Inelastic Neutron Scattering spectroscopy provides detailed vibrational spectra containing the fingerprint of the terminal C-H groups of carbon materials. From the experimental spectra, we observed clear differences among carbons having different origin, and a systematic decrease in the integrated area upon metal deposition that linearly scales with the nanoparticles dispersion. Density Functional Theory simulations are fundamental to assign the experimental bands to specific species. Thus, an extended simulation work on both regular and defective aromatic models was carried out, providing the inelastic neutron scattering fingerprint of a large number of different C-H terminations. By fitting the experimental spectra with a linear combination of the simulated spectra, it was possible to quantify the concentration of each terminal C-H geometry in the samples, and to identify the species most affected by the metal nanoparticles deposition. Specific benzene rings exposing a single C-H group appear to have a decisive role in the interaction with the metal nanoparticles and their deposition procedure.

Microplastics (MPs) remain largely understudied in Small Island Developing States. This study is aimed at comparing the abundance and characteristics of MPs in rural and urban marine coastal sites located along the southern coast of Fiji's main inhabited island, Viti Levu. Collection of subsurface waters (at depth of ca. 0.6 m) was performed at seven sites via Niskin bottle. Samples were filtered over a membrane filter to extract MPs and to allow visual analysis and polymer identification by using attenuated total reflectance in Fourier transform infrared spectroscopy. Findings from this study depict widespread presence of MPs in both urban and rural sites, and show no significant differences in the four parameters studied, i.e. abundance of MP pieces (2.0 vs 1.6 MP/L, respectively), form types (dominance of fibers), size (0.5–0.9 and 1.0–1.4 mm totaling 48% of the samples), and color (blue contributing 30%, and red and black contributing 25% each). These findings challenge the common expectation of a higher MPs pollution in urban areas compared to rural areas.

The motion of calcium alginate spheres in a liquid-solid fluidized bed is examined by radioactive particle tracking (RPT) and simulated by computational fluid dynamics coupled with discrete element method (CFD-DEM). Observables relevant for phenomenological models of the solid motion determined from RPT are compared with those arising from the CFD-DEM simulations. Bed expansion, solid distribution, time averaged velocity fields and axial dispersion coefficients calculated from simulations reasonably agree with the experimental values. The influence of the liquid inlet distribution on simulations results is examined. A non-negligible effect is observed on the predicted velocity profiles, solid distribution and dispersion coefficients, mainly in the entrance region. Uniform liquid distribution at the entrance generally predicts a less steeped profile. When the liquid inlet distribution is parameterized considering the geometry of the experimental distributor, the fitting of the solid mean axial velocity and solid distribution radial profiles, judged from a sum of squares of relative errors, improves in 90% and 80%, respectively, compared to results obtained when considering a uniform liquid distribution at the entrance. Fil: Maestri, Mauricio Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: Salierno, Gabriel Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: Piovano, Stella. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: Cassanello Fernandez, Miryam Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: Cardona, Maria Angelica. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Hojman, Daniel Leonardo. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Somacal, Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina

The Pacific Island Countries and Territories (PICTs) are heavily dependent on the marine resources for food security, employment, government revenue and economic development, hence the concern about the potential exposure of these resources to pollutants. The main goal of this review was to identify ecotoxicology studies published that were done in PICTs. Four major gaps were identified: i) a quantitative gap, with low number of studies published on the PICTs; ii) a geographic gap, where ecotoxicology studies have unevenly covered the different PICTs; iii) a temporal gap, as no biological effect monitoring study has so far been published for the PICTs; and, iv) a pollutants gap, as all of the PICTs studies focused mainly on environmental monitoring studying on average two types of pollutants (heavy metals and pesticides) per PICT only. We suggest, therefore, the potential risk to the marine environment to be estimated by assessing the fate of pollutants via chemical and biological effect monitoring.

We investigated the magnetic structure and dynamics of YbMnBi$_2$, with elastic and inelastic neutron scattering, to shed light on the topological nature of the charge carriers in the antiferromagnetic phase. We confirm C-type antiferromagnetic ordering of the Mn spins below $T_{\rm N} = 290$ K, and determine that the spins point along the $c$-axis to within about $3^\circ$. The observed magnon spectrum can be described very well by the same effective spin Hamiltonian as was used previously to model the magnon spectrum of CaMnBi$_2$. Our results show conclusively that the creation of Weyl nodes in YbMnBi$_2$ by the time-reversal-symmetry breaking mechanism can be excluded in the bulk.

The aim of this work is the development of a methodology for the technical and environmental assessment of biowaste valorization in 2G biorefineries. Italy was chosen as case study, considering years 2016&ndash, 2017. Approach: the Italian context was evaluated through the following key parameters: Gross domestic power, climate, demography, and population density distribution described the Italian framework. The four most abundant biowaste categories were defined through their amounts and geo-localization: wastewater and sewage sludge (WSS, 4.06 Mt/y), organic fraction of municipal solid waste (OFMSW, 1.7 Mt/y), agricultural livestock waste (ALW, 5.7 Mt/y), and waste deriving from the food industry (FIW, 2.6 Mt/y). The geo-localization and quantitative evaluations of the available biowaste amounts were aimed at defining the dimension and localization of the biorefinery plant and at optimizing supply and transport chains, while the qualitative characteristic were aimed to evaluate the most promising process among thermo-valorization (TH) and anaerobic digestion (AD). Results: All considered biowastes were appropriate for biorefinery processes, since carbon content exceeds 40% and the carbon&ndash, nitrogen ratio was between 10 and 30. All biowaste categories were evaluated as feedstocks for two biorefinery processes: anaerobic digestion (AD) and thermo-valorization (TH) with energy recovery. Compared to TH, AD achieved in all cases the best performances in terms of produced energy and avoided CO2 emissions. The primary energy production of AD and TH for WSS, OFMSW, ALW, and FIW were respectively: 7.89 vs. 2.4 kWh/kg, 8.7 vs. 2.6 kWh/kg, 10.85 vs. 5.5 kWh/kg, and 12.5 vs. 7.8 kWh/kg. The main findings of this work were: the adoption of AD was technically more suitable than TH, AD increased the avoided CO2 emissions of 10%&ndash, 89.9% depending on biowaste category.

Inelastic neutron scattering measurements on the molecular dimer-Mott insulator $\ensuremath{\kappa}\text{\ensuremath{-}}(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF}{)}_{2}\mathrm{Cu}[\mathrm{N}(\mathrm{CN}{)}_{2}]\mathrm{Cl}$ reveal a phonon anomaly in a wide temperature range. Starting from ${T}_{\mathrm{ins}}\ensuremath{\sim}50--60\text{ }\text{ }\mathrm{K}$ where the charge gap opens, the low-lying optical phonon modes become overdamped upon cooling towards the antiferromagnetic ordering temperature ${T}_{\mathrm{N}}=27\text{ }\text{ }\mathrm{K}$, where also a ferroelectric ordering at ${T}_{\mathrm{FE}}\ensuremath{\approx}{T}_{\mathrm{N}}$ occurs. Conversely, the phonon damping becomes small again when spins and charges are ordered below ${T}_{\mathrm{N}}$, while no change of the lattice symmetry is observed across ${T}_{\mathrm{N}}$ in neutron diffraction measurements. We assign the phonon anomalies to structural fluctuations coupled to charge and spin degrees of freedom in the BEDT-TTF molecules.

Coastal and estuarine systems provide critical shark habitats due to their relatively high productivity and shallow, protected waters. The young (neonates, young‐of‐the‐year, and juveniles) of many coastal shark species occupy a diverse range of habitats and areas where they experience environmental variability, including acute and seasonal shifts in local salinities and temperatures. Although the location and functioning of essential shark habitats has been a focus in recent shark research, there is a paucity of data from the South Pacific. In this study, we document the temporal and spatial distribution, age class composition, and environmental parameters of young bull sharks (Carcharhinus leucas) in the Rewa, Sigatoka, and Navua Rivers, Fiji's three largest riverine systems. One hundred and seventy‐two young bull sharks were captured in fisheries‐independent surveys from January 2016 to April 2018. The vast majority of the captures were neonates. Seasonality in patterns of occurrence of neonate individuals suggests a defined parturition period during summer. Environmental parameters between the Rewa and the Sigatoka River differed significantly, as did the recorded young bull sharks abundance. According to the surveys, young bull sharks occur in all three rivers with the Rewa River likely representing essential habitat for newly born bull sharks. These results enhance the understanding of bull shark ecology in Fiji and provide a scientific basis for the implementation of local conservation strategies that contribute to the protection of critical habitats., Ecology and Evolution, 9 (13), ISSN:2045-7758

The global reliance on pharmaceuticals coupled with the lack of effective treatment methods has resulted in pseudo-persistence of pharmaceuticals within the environment. Globally, efforts to quantify and monitor pharmaceuticals within the environment have been well underway, however few studies have been made within small Pacific Islands. This study aims at screening for the occurrence and concentration of pharmaceutical residues within the southern coastal waters of Fiji’s main island, Viti Levu. Water samples were collected from a depth of ca. 0.6 m from seven sites and were analyzed for 80 pharmaceuticals via a combination of chromatography and heated electrospray ionization. Seventy-two pharmaceuticals were quantified at least once with average concentrations ranging between 0.04 ng/L (diltiazem) and 19 ng/L (ketoconazole), and with all but two pharmaceuticals (trimethoprim and biperiden) being present in less than 50% of the samples. Findings suggest that even though the release of pharmaceuticals into the marine environment is sporadic and pharmaceuticals are diluted via turbulent mixing, there are measurable concentrations of pharmaceuticals in Fiji and these pollutants are not necessarily restricted to highly populated areas.

Coral reefs in the tropical Pacific region are exposed to a range of anthropogenic local pressures. Climate change is exacerbating local impacts, causing unprecedented declines in coral reef habitats and bringing negative socio-economic consequences to Pacific communities who depend heavily on coral reefs for food, income and livelihoods. Continued increases in greenhouse gas emissions will drive future climate change, which will accelerate coral reef degradation. Traditional systems of resource governance in Pacific island nations provide a foundation to address local pressures and build reef resilience to climate change. Management and adaptation options should build on the regional diversity of governance systems and traditional knowledge to support community-based initiatives and cross-sectoral cooperation to address local pressures and minimize climate change impacts. Such an inclusive approach will offer enhanced opportunities to develop and implement transformative adaptation solutions, particularly in remote and regional areas where centralized management does not extend.

In this work we investigated in detail the effects of nitric acid on the surface chemistry of two carbons, activated by steam and by phosphoric acid, meant to identify the nature and the concentration of the oxidized surface species. To this aim, the oxidized carbons were characterized by means of a large number of complementary techniques, including micro-Raman spectroscopy, N2 physisorption, Boehm titration method, 13C solid state nuclear magnetic resonance, X-ray photoelectron spectroscopy, diffuse reflectance infrared and inelastic neutron scattering spectroscopy. Carboxylic and carboxylate groups are mainly formed, the latter stabilized by the extended conjugation of the π electrons and being more abundant on small and irregular graphitic platelets. We demonstrated that the presence of oxygen-containing groups acts against the palladium dispersion and causes the appearance of an appreciable induction time in hydrogenation reactions. The carbon with more oxygenated surface species (and in particular more carboxylate groups) must be chosen in the hydrogenation of polar substrates, while it is detrimental to the hydrogenation of nonpolar substrates.

The purpose of this study was to investigate the effects of a circle hook ring on catch rates of target fish species and bycatch rates of sea turtles, elasmobranchs, and non-commercial fish in a shallow-set Italian swordfish longline fishery. Results were compared from 65 sets from six commercial fishing vessels totalling 50 800 hooks in which ringed and non-ringed 16/0 circle hooks with a 10° offset were alternated along the length of the longline. In total, 464 individuals were caught in the 4 years of experiment, with swordfish (Xiphias gladius) comprising 83% of the total number of animals captured. Catch rates of targeted swordfish were significantly higher on ringed hooks (CPUEringed hooks = 8.465, CPUEnon-ringed hooks = 6.654). Results indicate that ringed circle hooks captured significantly more small-sized swordfish than non-ringed circle hooks (27.7% vs. 19.5%, respectively). For species with sufficient sample sizes, the odds ratio (OR) of a capture was in favour of ringed hooks; significantly for swordfish (OR = 1.27 95%CI 1.04–1.57), and not significantly for bluefin tuna (Thunnus thynnus) (OR = 1.50, 95%CI 0.68–3.42) nor for pelagic stingray (Pteroplatytrigon violacea) (OR = 1.13, 95%CI 0.54–2.36). All six loggerhead turtles (Caretta caretta) and three of the four blue sharks (Prionace glauca) were captured on ringed hooks, however, the small sample sizes prevented meaningful statistical analysis. In summary, results from this study suggest that the addition of a ring to 16/0 circle hooks confers higher catchability for small-sized commercial swordfish, and does not significantly reduce catch rate of bycatch species and protected species in a Mediterranean shallow pelagic longline fishery. These findings should motivate fisheries managers to consider factors in addition to hook shape when aiming to promote sustainable fishing practices. The presence of a ring has the potential to negate some conservation benefits. Copyright © 2016 John Wiley & Sons, Ltd.

Pelagic longline fisheries for relatively fecund tuna and tuna-like species can have large adverse effects on incidentally caught species with low-fecundity, including elasmobranchs. Analyses of observer programme data from the Fiji longline fishery from 2011 to 2014 were conducted to characterize the shark and ray catch composition and identify factors that significantly explained standardized catch rates. Catch data were fitted to generalized linear models to identify potentially significant explanatory variables. With a nominal catch rate of 0.610 elasmobranchs per 1000 hooks, a total of 27 species of elasmobranchs were captured, 48% of which are categorized as Threatened under the IUCN Red List. Sharks and rays made up 2.4% and 1.4%, respectively, of total fish catch. Blue sharks and pelagic stingrays accounted for 51% and 99% of caught sharks and rays, respectively. There was near elimination of ‘shark lines’, branchlines set at or near the sea surface via attachment directly to floats, after 2011. Of caught elasmobranchs, 35% were finned, 11% had the entire carcass retained, and the remainder was released alive or discarded dead. Finning of elasmobranchs listed in CITES Appendix II was not observed in 2014. There were significantly higher standardized shark and ray catch rates on narrower J-shaped hooks than on wider circle hooks. Based on findings from previous studies on single factor effects of hook width and shape, the smaller minimum width of the J-shaped hooks may have caused the higher shark and ray catch rates. For sharks, the effect of hook width may have exceeded the effect of hook shape, where small increases in shark catch rates have been observed on circle vs J-shaped hooks. Shark and ray standardized catch rates were lowest in the latter half of the year. Focusing effort during the second half of the year could reduce elasmobranch catch rates. Copyright © 2016 John Wiley & Sons, Ltd.