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Compilation and scrutiny of all accessible specimen and observer records of the long-tailed woodnymph Thalurania watertonii, a hummingbird currently listed as ‘Endangered’ on the IUCN Red List, eliminates Guyana, Pará, Maranhão, Ceará, Rio Grande do Norte and Paraíba from its range and sets aside both Sergipe and Bahia as unproven, leaving 29 certain localities, 15 in Pernambuco and 14 in Alagoas, north-east Brazil, all of them in Atlantic Forest and not Cerrado or Caatinga. Among them are records from ten IUCN category I‒IV protected areas (seven in Pernambuco, two in Alagoas and one shared between the two). Remote sensing analysis shows all confirmed localities to contain a total of c.292 km2 of forest (with an extent of occurrence (EOO) and area of occupancy (AOO) of 16,090 and 910 km2, respectively), thus indicating the species qualifies for ‘Vulnerable’ (rather than ‘Endangered’) on the IUCN Red List. However, within the species’ range, we find a maximum total of 2568 km2 of forest, unexplored patches of which may host important populations of this and other threatened species endemic to the ‘Pernambuco Centre of Endemism’. Range-wide research is urgently needed into the condition of these sites and the status of the species within them as well as the general densities, ecology and true distribution of the species, which is now known to breed from October to March, to feed on at least 25 plant species and possibly to need shallow clean-water streams, in order to identify the key measures needed to ensure its survival.

Determining the nature and extent of covalency of early actinide chemical bonding is a fundamentally important challenge. Recently, X-ray absorption, electron paramagnetic, and nuclear magnetic resonance spectroscopic studies have probed actinide-ligand covalency, largely confirming the paradigm of early actinide bonding varying from ionic to polarised-covalent, with this range sitting on the continuum between ionic lanthanide and more covalent d transition metal analogues. Here, we report measurement of the covalency of a terminal uranium(VI)-nitride by 15N nuclear magnetic resonance spectroscopy, and find an exceptional nitride chemical shift and chemical shift anisotropy. This redefines the 15N nuclear magnetic resonance spectroscopy parameter space, and experimentally confirms a prior computational prediction that the uranium(VI)-nitride triple bond is not only highly covalent, but, more so than d transition metal analogues. These results enable construction of general, predictive metal-ligand 15N chemical shift-bond order correlations, and reframe our understanding of actinide chemical bonding to guide future studies. Determining the covalency of actinide chemical bonding is a fundamentally important challenge. Here, the authors report a 15N nuclear magnetic resonance spectroscopy study of a terminal uranium-nitride, revealing exceptional NMR properties and covalency that redefine 15N NMR parameter space and actinide chemical bonding.

We report the use of 29Si NMR spectroscopy and DFT calculations combined to benchmark the covalency in the chemical bonding of s- and f-block metal-silicon bonds. The complexes [M(SitBu3)2(THF)2(THF)x] (1-M: M = Mg, Ca, Yb, x = 0; M = Sm, Eu, x = 1) and [M(SitBu2Me)2(THF)2(THF)x] (2-M: M = Mg, x = 0; M = Ca, Sm, Eu, Yb, x = 1) have been synthesized and characterized. DFT calculations and 29Si NMR spectroscopic analyses of 1-M and 2-M (M = Mg, Ca, Yb, No, the last in silico due to experimental unavailability) together with known {Si(SiMe3)3}-, {Si(SiMe2H)3}-, and {SiPh3}-substituted analogues provide 20 representative examples spanning five silanide ligands and four divalent metals, revealing that the metal-bound 29Si NMR isotropic chemical shifts, ?Si, span a wide (?225 ppm) range when the metal is kept constant, and direct, linear correlations are found between ?Si and computed delocalization indices and quantum chemical topology interatomic exchange-correlation energies that are measures of bond covalency. The calculations reveal dominant s- and d-orbital character in the bonding of these silanide complexes, with no significant f-orbital contributions. The ?Si is determined, relatively, by paramagnetic shielding for a given metal when the silanide is varied but by the spin-orbit shielding term when the metal is varied for a given ligand. The calculations suggest a covalency ordering of No(II) > Yb(II) > Ca(II) ≈ Mg(II), challenging the traditional view of late actinide chemical bonding being equivalent to that of the late lanthanides.

We used photo-documented citizen science data held in publicly accessible databases to better elucidate the diet of one of the smallest Neotropical Accipitridae, the Tiny Hawk (Accipiter superciliosus). Previous data are exclusively anecdotal, but a suggestion that this species is to some extent a specialized predator on hummingbirds (Trochilidae) is widely reported in the literature, despite being based on few observations. Using a total of more than 680 photographs of Tiny Hawks, we identified 33 items of avian prey from 15 families and at least 25 genera, including one hummingbird and some comparatively large non-passerines. Prey also included one bat. Although the Tiny Hawk is perhaps more liable to predate hummingbirds than most other Neotropical raptors, the available data suggest that the Tiny Hawk, like many other Accipiter species, is primarily a bird specialist. As evidenced by other recently published studies, internet-sourced photographs might prove useful for similar dietary analyses for other poorly known raptors.

High-pressure single-crystal X-ray diffraction patterns on five synthetic Mg-Al tourmalines with near end-member compositions [dravite NaMg3Al6Si6O18(BO3)3(OH)3OH, K-dravite KMg3Al6Si6O18(BO3)3(OH)3OH, magnesio-foitite □(Mg2Al)Al6Si6O18(BO3)3(OH)3OH, oxy-uvite CaMg3Al6Si6O18(BO3)3(OH)3O, and olenite NaAl3Al6Si6O18(BO3)3O3OH, where □ represents an X-site vacancy] were collected to 60 GPa at 300 K using a diamond-anvil cell and synchrotron radiation. No phase transitions were observed for any of the investigated compositions. The refined unit-cell parameters were used to constrain third-order Birch-Murnaghan pressure-volume equation of states with the following isothermal bulk moduli (K0 in GPa) and corresponding pressure derivatives (K0′ = ∂K0/∂P)T: dravite K0 = 97(6), K0′ = 5.0(5); K-dravite K0 = 109(4), K0′ = 4.3(2); oxy-uvite K0 = 110(2), K0′ = 4.1(1); magnesio-foitite K0 = 116(2), K0′ = 3.5(1); olenite K0 = 116(6), K0′ = 4.7(4). Each tour-maline exhibits highly anisotropic behavior under compression, with the c axis 2.8–3.6 times more compressible than the a axis at ambient conditions. This anisotropy decreases strongly with increasing pressure and the c axis is onlŷ14% more compressible than the a axis near 60 GPa. The octahedral Y- and Z-sites' composition exerts a primary control on tourmaline's compressibility, whereby Al content is correlated with a decrease in the c-axis compressibility and a corresponding increase in K0 and K0′. Contrary to expectations, the identity of the X-site-occupying ion (Na, K, or Ca) does not have a demonstrable effect on tourmaline's compression curve. The presence of a fully vacant X site in magnesio-foitite results in a decrease of K0′ relative to the alkali and Ca tourmalines. The decrease in K0′ for magnesio-foitite is accounted for by an increase in compressibility along the a axis at high pressure, reflecting increased compression of tourmaline's ring structure in the presence of a vacant X site. This study highlights the utility of synthetic crystals in untangling the effect of composition on tourmaline's compression behavior.

Dusts generated during ferrochrome smelting in a pilot-scale DC arc furnace were sampled from the furnace freeboard and from the off-gas handling stream (cyclone and baghouse). The dusts comprise fine-grained feed material (chromite, flux, and reductant); compositionally heterogeneous, glassy micro-spherules, interpreted as gas condensates and/or aerosolized melt droplets; and trace amounts of ferrochrome. Synchrotron-based micro-X-ray-fluorescence and micro-X-ray absorption near-edge structure around the chromium (Cr) K-edge was used to identify the distribution and speciation of Cr in dust particulates from the freeboard and the cyclone. The dust samples contain Cr in multiple oxidation states, including Cr(0) (hosted by ferrochrome), Cr(III), and Cr(VI). The majority of Cr occurs as Cr(III) in chromite. In both the furnace-freeboard and the cyclone dusts, Cr(VI) was consistently associated with the Si-Ca-Mg-rich micro-spherules. A major finding of this study is that Cr oxidation and Cr(VI) formation can occur in aerosolized dusts within the closed DC-arc furnace during ferrochrome smelting under conditions that are deemed to be essentially reducing. The association of Cr(VI) with the micro-spherules forwards the hypothesis that the high temperature of the furnace off-gasses and the flux composition influence the likelihood of Cr(VI) formation within a closed furnace under open-bath smelting conditions.

Depression is undertreated in patients with chronic kidney disease (CKD) stage 4 without kidney replacement therapy (KRT), despite evidence showing its association with an increase in morbidity and mortality. Earlier and more adequate identification of patients with depression is needed. A quasi-experimental evidence-based project included 33 patients with CKD stage 4 not on KRT from a local nephrology office. The patients, who had previously been screened with the Patient Health Questionnaire-2 (PHQ-2), were screened with the Beck Depression Inventory. Nine patients (27%) had Beck Depression Inventory scores suggesting the need for a mental health referral compared to none having the need for a mental health referral captured by the PHQ-2. Results of this study indicate that screening with the Beck Depression Inventory should be considered to more accurately identify patients with depressive symptoms so interventions can occur earlier.

The response of forsterite, Mg2SiO4, under dynamic compression is of fundamental importance for understanding its phase transformations and high‐pressure behavior. Here, we have carried out an in situ X‐ray diffraction study of laser‐shocked polycrystalline and single‐crystal forsterite (a‐, b‐, and c‐ orientations) from 19 to 122 GPa using the Matter in Extreme Conditions end‐station of the Linac Coherent Light Source. Under laser‐based shock loading, forsterite does not transform to the high‐pressure equilibrium assemblage of MgSiO3 bridgmanite and MgO periclase, as has been suggested previously. Instead, we observe forsterite and forsterite III, a metastable polymorph of Mg2SiO4, coexisting in a mixed‐phase region from 33 to 75 GPa for both polycrystalline and single‐crystal samples. Densities inferred from X‐ray diffraction data are consistent with earlier gas‐gun shock data. At higher stress, the response is sample‐dependent. Polycrystalline samples undergo amorphization above 79 GPa. For [010]‐ and [001]‐oriented crystals, a mixture of crystalline and amorphous material is observed to 108 GPa, whereas the [100]‐oriented forsterite adopts an unknown phase at 122 GPa. The first two sharp diffraction peaks of amorphous Mg2SiO4 show a similar trend with compression as those observed for MgSiO3 in both recent static‐ and laser‐driven shock experiments. Upon release to ambient pressure, all samples retain or revert to forsterite with evidence for amorphous material also present in some cases. This study demonstrates the utility of femtosecond free‐electron laser X‐ray sources for probing the temporal evolution of high‐pressure silicate structures through the nanosecond‐scale events of shock compression and release.

We report the synthesis and characterisation of isostructural thorium(IV)- and uranium(IV)- silanide complexes, providing the first structurally authenticated Th-Si bond and a rare example of a molecular U-Si bond. These complexes therefore present the first opportunity to directly compare the chemical bonding of Th-Si and U-Si bonds. Quantum chemical calculations show significant and surprisingly similar 7s, 6d, and 5f orbital contributions from both actinide (An) elements in polarised covalent An-Si bonds

Covalency is complex yet central to our understanding of chemical bonding, particularly in the actinide series. Here we assess covalency in a series of isostructural d and f transition element compounds M(OC

Tourmaline is a common accessory mineral in the metasedimentary Pfitsch Formation located in the Pfitscher Joch (Passo de Vizze) area in the Tauern Window of the Eastern Alps. These post-Variscan metasedimentary units experienced peak metamorphic conditions of ~ 550 °C, 1.0 GPa during the Alpine orogeny. Tourmaline is most abundant in a ~ 25 m thick unit of feldspathic gneiss (~ 20–200 μg/g B), where it occurs as idiomorphic crystals typically 10 mm in length. The abundance and size of the tourmaline crystals increase near coarse-grained quartzofeldspathic segregations (~ 1200 μg/g B), reflecting the mobilization and concentration of B by metamorphic fluids. Near segregations, individual tourmaline crystals have up to three growth zones, recording pro- (~ 350–500 °C, 0.7–1.0 GPa) and retrograde (~ 400 °C, 0.2 GPa) growth as determined by combining textural information and sector-zoning thermometry. Retrograde tourmaline occurs as individual crystals as well as overgrowths on prograde tourmaline crystals, especially on the surface of extensional fractures formed by E–W extension during regional decompression. Tourmaline in the Pfitsch Formation is dravitic with a variable Fe content that correlates with the Fe content of its respective host unit. Charge balance calculations suggest that a significant proportion of Fe in tourmaline is ferric, supporting the interpretation of a subaerial continental sedimentary protolith. Tourmaline near segregations has the highest inferred ferric iron content, which decreases across growth zones, potentially reflecting a reduction of the fluid during metamorphism. The Mg/(Mg + Fe) ratio increases with prograde tourmaline growth and decreases in retrograde overgrowths. In contrast, the Ca/(Ca + Na) ratio increases gradually from 0.05 to 0.20 with prograde growth and continues to increase up to 0.25 in the retrograde overgrowths, recording the maximum Ca/(Ca + Na) ratio of the fluid during Alpine metamorphism. The metasediments of the Pfitsch Formation have very low and variable whole-rock δ 11 B values (− 14.1 to − 33.6‰), with the highest values (− 17.7 to − 14.1‰) found in B-rich samples (165–1200 μg/g B) containing abundant tourmaline, and the lowest values (− 24.2 to − 33.6‰) in B-depleted samples (21–40 μg/g), which lack tourmaline. This observation supports preferential loss of 11 B from the rocks during prograde metamorphism. Zoned tourmaline crystals in the Pfitsch formation show successively decreasing B isotope ratios from − 7.8 to − 11.2‰ in their cores and − 17.3 to − 20.3‰ in their rims. As supported by a Rayleigh fractionation model, the B-isotope values of the host rocks and the tourmaline crystals are most easily explained by the internal redistribution of B from a B-rich precursor mineral (e.g. mica) to the tourmaline during Alpine metamorphism.

A series of compounds M(OC6H5)4 (M = Ti, Zr, Hf, Ce, Th, U) is studied with hybrid density functional theory, to assess M-O bond covalency. The series allows for the comparison of d and f element compounds that are structurally similar. Two well-estabilished analysis methods are employed: Natural Bond Orbital and the Quantum Theory of Atoms in Molecules. A consistent pattern emerges; the U-O bond is the most covalent, followed by Ce-O and Th-O, with those involving the heavier transition metals the least so. The covalency of the Ti-O bond differs relative to Ce-O and Th-O, with the orbital-based method showing greater relative covalency for Ti than the electron density-based methods. The deformation energy of r(M-O) correlates with the d orbital contribution from the metal to the M-O bond, while no such correlation is found for the f orbital component. f orbital involvement in M-O bonding is an important component of covalency, facilitating orbital overlap and allowing for greater expansion of the electrons, thus lowering their kinetic energy.

Liveability is a concept closely related to the notion of well-being and refers to the environmental conditions that contribute to the quality of life, alongside individual features. Subjective and objective measurements of liveability are both of considerable practical and theoretical importance. A survey is conducted in this paper by which individuals tend to shape their preferences according to six factors describing various aspects of living conditions: (1) home, (2) neighbourhood, (3) transport, (4) entertainment, (5) services and (6) work. The survey data helps us to work out some indicators representing the perceived liveability in the targeted areas. A linear mixed model is used to explore possible relationships between objective factors and perceived liveability. A model-based estimate of liveability index can be then calculated for each non-sampled individual based on his/her socio-demographic characteristics and area of living.

Agent based modelling has been widely accepted as a promising tool for urban planning purposes thanks to its capability to provide sophisticated insights into the social behaviours and the interdependencies that characterise urban systems. In this paper, we report on an agent based model, called TransMob, which explicitly simulates the mutual dynamics between demographic evolution, transport demands, housing needs and the eventual change in the average satisfaction of the residents of an urban area. The ability to reproduce such dynamics is a unique feature that has not been found in many of the like agent based models in the literature. TransMob, is constituted by six major modules: synthetic population, perceived liveability, travel diary assignment, traffic micro-simulator, residential location choice, and travel mode choice. TransMob is used to simulate the dynamics of a metropolitan area in South East of Sydney, Australia, in 2006 and 2011, with demographic evolution. The results are favourably compared against survey data for the area in 2011, therefore validating the capability of TransMob to reproduce the observed complexity of an urban area. We also report on the application of TransMob to simulate various hypothetical scenarios of urban planning policies. We conclude with discussions on current limitations of TransMob, which serve as suggestions for future developments.

The crystal structures of synthetic K-dravite [XKYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], dravite [XNaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], oxy-uvite [XCaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W O], and magnesio-foitite [X☐Y(Mg2Al)ZAl 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)] are investigated by polarized Raman spectroscopy, single-crystal structure refinement (SREF), and powder X-ray diffraction. The use of compositionally simple tourmalines characterized by electron microprobe analysis facilitates the determination of site occupancy in the SREF and band assignment in the Raman spectra. The synthesized K-dravite, oxy-uvite, and magnesio-foitite have significant Mg–Al disorder between their octahedral sites indicated by their respective average 〈Y–O〉 and 〈Z–O〉 bond lengths. The Y- and Z-site compositions of oxy-uvite (YMg1.52Al1.48(10) and ZAl4.90Mg1.10(15)) and magnesio-foitite (YAl1.62Mg1.38(18) and ZAl4.92Mg1.08(24)) are refined from the electron densities at each site. The Mg–Al ratio of the Y and Z sites is also determined from the relative integrated peak intensities of the Raman bands in the O–H stretching vibrational range (3250–3850 cm−1), producing values in good agreement with the SREF data. The unit cell volume of tourmaline increases from magnesio-foitite (1558.4(3) A3) to dravite (1569.5(4)–1571.7(3) A3) to oxy-uvite (1572.4(2) A3) to K-dravite (1588.1(2) A3), mainly due to lengthening of the crystallographic c-axis. The increase in the size of the X-site coordination polyhedron from dravite (Na) to K-dravite (K) is accommodated locally in the crystal structure, resulting in the shortening of the neighboring O1–H1 bond. In oxy-uvite, Ca2+ is locally associated with a deprotonated W (O1) site, whereas vacant X sites are neighbored by protonated W (O1) sites. Increasing the size of the X-site-occupying ion does not detectably affect bonding between the other sites; however, the higher charge of Ca and the deprotonated W (O1) site in oxy-uvite are correlated to changes in the lattice vibration Raman spectrum (100–1200 cm−1), particularly for bands assigned to the T 6O18 ring. The Raman spectrum of magnesio-foitite shows significant deviations from those of K-dravite, dravite, and oxy-uvite in both the lattice and O–H stretching vibrational ranges (100–1200 and 3250–3850 cm−1, respectively). The vacant X site is correlated with long- and short-range changes in the crystal structure, i.e., deformation of the T 6O18 ring and lengthening of the O1–H1 and O3–H3 bonds. However, X-site vacancies in K-dravite, dravite, and oxy-uvite result only in the lengthening of the neighboring O1–H1 bond and do not result in identifiable changes in the lattice-bonding environment.

Predicting the correct ground-state multiplicity for iron(II) porphyrin, a high-spin quintet, remains a significant challenge for electronic-structure methods, including commonly employed density functionals. An even greater challenge for these methods is correctly predicting favorable binding of O2 to iron(II) porphyrin, due to the open-shell singlet character of the adduct. In this work, the performance of a modest set of contemporary density-functional approximations is assessed and the results interpreted using Bader delocalization indices. It is found that inclusion of greater proportions of Hartree-Fock exchange, in hybrid or range-separated hybrid functionals, has opposing effects; it improves the ability of the functional to identify the ground state but is detrimental to predicting favorable dioxygen binding. Because of the uncomplementary nature of these properties, accurate prediction of both the relative spin-state energies and the O2 binding enthalpy eludes conventional density-functional approximations.

Steel production is currently the largest industrial source of atmospheric CO2. As annual steel production continues to grow, the need for effective methods of reducing its carbon footprint increases correspondingly. The carbonation of the calcium-bearing phases in steel slag generated during basic oxygen furnace (BOF) steel production, in particular its major constituent, larnite {Ca2SiO4}, which is a structural analogue of olivine {(MgFe)2SiO4}, the main mineral subjected to natural carbonation in peridotites, offers the potential to offset some of these emissions. However, the controls on the nature and efficiency of steel slag carbonation are yet to be completely understood. Experiments were conducted exposing steel slag grains to a CO2-H2O mixture in both batch and flow-through reactors to investigate the impact of temperature, fluid flux, and reaction gradient on the dissolution and carbonation of steel slag. The results of these experiments show that dissolution and carbonation of BOF steel slag are more efficient in a flow-through reactor than in the batch reactors used in most previous studies. Moreover, they show that fluid flux needs to be optimized in addition to grain size, pressure, and temperature, in order to maximize the efficiency of carbonation. Based on these results, a two-stage reactor consisting of a high and a low fluid-flux chamber is proposed for CO2 sequestration by steel slag carbonation, allowing dissolution of the slag and precipitation of calcium carbonate to occur within a single flow-through system.

In travel demand models, traditional objective attributes (TOAs) are very commonly used as explanatory variables. Nowadays, it is understood that latent variables (LVs) also significantly influence travellers' behaviour. A hybrid choice modelling approach allows LVs in mode choice utility functions to be addressed. Specifically, a hybrid random parameter logit (HRPL) model has been developed to explore these influences. In this study, a traditional RPL (TRPL) model is compared with an HRPL model. For the later model, a two-step approach (also known as sequential approach) is implemented to incorporate LVs in choice models. Step 1 is the estimation of a MIMIC (multiple indicators and multiple causes) model; a type of regression model with a latent dependent variable(s). Step 2 is the estimation of a choice model with random parameters; information from the first step is incorporated in the second step. The paper analyses and compares the results of applying these models to a real urban case study using two datasets: 2008/09 and 2010/11 household travel survey (HTS) of Sydney Statistical Division (SSD), and also evaluates the predicted changes of mode choice probabilities based on hypothetical scenarios. Our results show that the HRPL model is superior to TRPL models that ignore the effect of LVs on traveller choice. The minimal changes in the parameter coefficients between the two datasets for each model suggest that the changes in traveller choice behaviour are gradual. Three hypothetical scenarios are simulated to forecast the changes that would be relevant to transport policy responses.

In many developed countries including Australia, infrastructure services at local and state levels are being provided by an increasing number of disjointed public and private agencies. There is an urgent need for an integrated view on the provision and use of these services for better governance and productivity. Developing an integrated view is challenging due to the dispersion of relevant data sets and the underlying complexity of increasingly interconnected infrastructure networks. Using a case study in New South Wales (Australia), we demonstrate how tools and processes in Geospatial Business Intelligence (Geo-BI) can be harnessed using a collective design approach to develop an integrated solution; the SMART Infrastructure Dashboard (SID). While providing a much needed planning and policy support tool for the local governance of infrastructure services, SID pushes the boundary of Geo-BI beyond its traditional use.

Opinions of individuals in real social networks are arguably strongly influenced by external determinants, such as the opinions of those perceived to have the highest levels of authority. In order to model this, we have extended an existing model of consensus formation in an adaptive network by the introduction of a parameter representing each agent's level of 'authority', based on their opinion relative to the overall opinion distribution. We found that introducing this model, along with a randomly varying opinion convergence factor, significantly impacts the final state of converged opinions and the number of interactions required to reach that state. We also determined the relationship between initial and final network topologies for this model, and whether the final topology is robust to node removals. Our results indicate firstly that the process of consensus formation with a model of authority consistently transforms the network from an arbitrary initial topology to one with distinct measurements in mean shortest path, clustering coefficient, and degree distribution. Secondly, we found that subsequent to the consensus formation process, the mean shortest path and clustering coefficient are less affected by both random and targeted node disconnection. Speculation on the relevance of these results to real world applications is provided. Refereed/Peer-reviewed

The reduced transition probability B(E2;0(+) -> 2(+)) has been measured for the neutron-rich nucleus Ni-74 in an intermediate energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory at Michigan State University. The obtained B(E2;0(+) -> 2(+)) = 642(-226)(+216) e(2) fm(4) value defines a trend which is unexpectedly small if referred to Ni-70 and to a previous indirect determination of the transition strength in Ni-74. This indicates a reduced polarization of the Z = 28 core by the valence neutrons. Calculations in the pfgd model space reproduce well the experimental result indicating that the B(E2) strength predominantly corresponds to neutron excitations. The ratio of the neutron and proton multipole matrix elements supports such an interpretation.

The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic ob- servables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the ef- fective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope ( 64 Ni) towards the 78 Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently per- formed an experiment with the goal to extract the B(E2; 0 + ! 2 + ) value for the 74 Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.

Ca–Na partitioning between tourmaline and a coexisting fluid is investigated in the system CaO–Na2O–B2O3–Al2O3–MgO–SiO2–H2O–Cl between 0.2–4.0 GPa and 500–700 °C. The synthesis experiments produced a mineral assemblage of tourmaline, coesite/quartz, and in some cases additional phases, typically comprising 1.0 GPa, Ca partitions preferentially into the fluid, resulting in Na-dominant tourmaline compositions. Temperature has a secondary effect on Ca–Na partitioning, with higher temperatures correlating with increased Ca incorporation in tourmaline. Based on the experimental findings, tourmaline is expected to have Ca-rich compositions when it forms in low pressure, high-temperature Ca-rich rocks, consistent with the current record of tourmaline occurrence. The bulk Mg/Al ratio and the pH of the tourmaline-forming system may also affect Ca incorporation in tourmaline, but remain to be investigated experimentally.

In this chapter, we discuss the influence of an anisotropic protein environment on the reaction mechanisms of saccharopine reductase and uroporphyrinogen decarboxylase, respectively, via the use of a quantum mechanical and molecular mechanical (QM/MM) approach. In addition, we discuss the importance of selecting a suitable DFT functional to be used in a QM/MM study of a key intermediate in the mechanism of 8R-lipoxygenase, a nonheme iron enzyme. In the case of saccharopine reductase, while the enzyme utilizes a substrate-assisted catalytic pathway, it was found that only through treating the polarizing effect of the active site, via the use of an electronic embedding formalism, was agreement with experimental kinetic data obtained. Similarly, in the case of uroporphyrinogen decarboxylase, the effect of the protein environment on the catalytic mechanism was found to be such that the calculated rate-limiting barrier is in good agreement with related experimentally determined values for the first decarboxylation of the substrate. For 8R-lipoxygenase, it was found that the geometries and energies of the multicentered open-shell intermediate complexes formed during the mechanism are quite sensitive to the choice of the density functional theory method. Thus, while density functional theory has become the method of choice in QM/MM studies, care must be taken in the selection of a particular high-level method.

Due to the similar ionic radius of K + and NH 4 + , K-silicates can incorporate a significant amount of NH 4 . As tourmaline is able to accommodate K in its crystal structure at high and ultrahigh pressure, we test if this also holds true for NH 4 . Piston-cylinder experiments in the system (NH 4 ) 2 O-MgO-SiO 2 -Al 2 O 3 -B 2 O 3 -H 2 O at 4.0 GPa, 700 °C, with B 2 O 3 and NH 4 OH in excess produce an assemblage of tourmaline, phengite, and coesite. The tourmaline crystals are up to 10 × 40 μm in size. EMP analyses indicate that the tourmalines contain 0.22 (±0.03) wt% (NH 4 ) 2 O and are solid solutions mainly along the magnesio-foitite and “NH 4 -dravite” join with the average structural formula X [(NH 4 ) 0.08(1) □ 0.92(1) ] Y [Mg 2.28(8) Al 0.72(8) ] Z [Al 5.93(6) Si 0.07(6) ] T [Si 6.00(5) O 18 ](BO 3 ) 3 (OH) 4 . NH 4 incorporation is confirmed by characteristic stretching and bending modes in the IR-spectra of single crystals on synthetic tourmaline. Further evidence is the increased unit-cell parameters of the tourmaline [ a = 15.9214(9) A, c = 7.1423(5) A, V = 1567.9(2) A 3 ] relative to pure magnesio-foitite. Incorporation of NH 4 in natural tourmaline was tested in a tourmaline-bearing mica schists from a high- P /low- T (>1.2 GPa/550 °C) metasedimentary unit of the Erzgebirge, Germany, rich in NH 4 . The NH 4 -concentrations in the three main NH 4 -bearing phases are: biotite (~1400 ppm) > phengite (~700 ppm) > tourmaline (~500 ppm). This indicates that tourmaline can act as important carrier of nitrogen between the crust and the deep Earth, which has important implications for a better understanding of the large-scale light element cycle.

In this chapter, we discuss the influence of an anisotropic protein environment on the reaction mechanisms of saccharopine reductase and uroporphyrinogen decarboxylase, respectively, via the use of a quantum mechanical and molecular mechanical (QM/MM) approach. In addition, we discuss the importance of selecting a suitable DFT functional to be used in a QM/MM study of a key intermediate in the mechanism of 8R-lipoxygenase, a nonheme iron enzyme. In the case of saccharopine reductase, while the enzyme utilizes a substrate-assisted catalytic pathway, it was found that only through treating the polarizing effect of the active site, via the use of an electronic embedding formalism, was agreement with experimental kinetic data obtained. Similarly, in the case of uroporphyrinogen decarboxylase, the effect of the protein environment on the catalytic mechanism was found to be such that the calculated rate-limiting barrier is in good agreement with related experimentally determined values for the first decarboxylation of the substrate. For 8R-lipoxygenase, it was found that the geometries and energies of the multicentered open-shell intermediate complexes formed during the mechanism are quite sensitive to the choice of the density functional theory method. Thus, while density functional theory has become the method of choice in QM/MM studies, care must be taken in the selection of a particular high-level method.

Tourmaline was synthesized in the system MgO–Al2O3–B2O3–SiO2–KCl–NaCl–H2O from an oxide mixture and excess fluid at 500–700 °C and 0.2–4.0 GPa to investigate the effect of pressure, temperature, and fluid composition on the relative incorporation of Na and K in dravitic tourmaline. Incorporation of K at the X-site increases with pressure, temperature, and KCl concentration; a maximum of 0.71 K pfu (leaving 0.29 X-vacant sites pfu) was incorporated into K-dravite synthesized at 4.0 GPa, 700 °C from a 4.78 m KCl, Na-free fluid. In contrast, Na incorporation depends predominately on fluid composition, rather than pressure or temperature; dravite with the highest Na content of 1.00 Na pfu was synthesized at 0.4 GPa and 700 °C from a 3.87 m NaCl and 1.08 m KCl fluid. All synthesized crystals are zoned, and the dominant solid solution in the Na- and K-bearing system is between magnesio-foitite [□(Mg2Al)Al6Si6O18(BO3)3(OH)3OH] and dravite [NaMg3Al6Si6O18(BO3)3(OH)3(OH)], with the dravitic component increasing with the concentration of Na in the fluid. In the K-bearing, Na-free system, the dominant solid solution is between magnesio-foitite and K-dravite [KMg3Al6Si6O18(BO3)3(OH)3(OH)], with the K-dravitic component increasing with pressure, temperature, and the concentration of K in the fluid. The unit-cell volume of tourmaline increases with K incorporation from 1555.1(3) to 1588.1(2) A3, reflecting the incorporation of the relatively large K+ ion. Comparison of our results to the compositional data for maruyamaite (K-dominant tourmaline) from the ultrahigh-pressure rocks of the Kokchetav Massif in Kazakhstan suggests that the latter was formed in a K-rich, Na-poor environment at ultrahigh-pressure conditions near the diamond-stability field.

We study the effective resistance of small-world resistor networks. Utilizing recent analytic results for the propagator of the Edwards-Wilkinson process on small-world networks, we obtain the asymptotic behavior of the disorder-averaged two-point resistance in the large system-size limit. We find that the small-world structure suppresses large network resistances: both the average resistance and its standard deviation approaches a finite value in the large system-size limit for any non-zero density of random links. We also consider a scenario where the link conductance decays as a power of the length of the random links, $l^{-\alpha}$. In this case we find that the average effective system resistance diverges for any non-zero value of $\alpha$., Comment: 15 pages, 6 figures