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Few physical or chemical processes defy well-established laws of mass-dependent isotopic fractionation. A surprising example, discovered two decades ago, is that thermal decomposition of calcium and magnesium carbonate minerals (conducted in vacuo, to minimise back-reaction and isotopic exchange) causes the oxygen triple-isotope compositions of the resulting solid oxide and CO2 to fit on parallel mass-dependent fractionation lines in ln(1 + δ17O) versus ln(1 + δ18O) space, with anomalous depletion of 17O in the solid and equivalent enrichment of 17O in the CO2. By investigating the thermal decomposition of other natural divalent metal carbonates and one synthetic example, under similar conditions, we find that the unusual isotope effect occurs in all cases and that the magnitude of the anomaly (Δ'17O) seems to depend on the room temperature crystallographic structure of the carbonate. A lower cation coordination number (as associated with smaller cation radius) correlates with a Δ'17O value closer to zero. Local symmetry considerations may therefore be influential. Relative to a reference fractionation line of slope 0.524 and passing through VSMOW, solid oxides produced by thermal decomposition of orthorhombic carbonates were characterised by Δ'17O = −0.367 ± 0.004‰ (standard error). The comparable figure from rhombohedral examples was −0.317 ± 0.010‰, whereas from the sole monoclinic (synthesised) specimen it was −0.219 ± 0.011‰. The numerical values are, to some extent, dependent on details of the experimental procedure. We discuss potential origins of the isotopic anomaly, including the possibility of hyperfine coupling between 17O nuclei and unpaired electrons of transient radicals (the ‘magnetic isotope effect’). A new mechanism based on the latter process is proposed. The associated transition state is compatible with that suggested by recent quantum chemical and kinetic studies of the thermal decompositions of calcite and magnesite. An earlier suggestion based on the magnetic isotope effect is shown to be incompatible with the generation of a 17O anomaly, regardless of the identity of the carbonate. We cannot exclude the possibility that a Fermi resonance between states leading to dissociation may additionally affect the magnitude of Δ'17O in some cases. Our findings have cosmochemical implications, with thermal processing of carbonates providing a potential mechanism for the mass-independent fractionation of oxygen isotopes in protoplanetary systems.

The lowermost portion of Earth’s mantle (D″) above the core−mantle boundary shows anomalous seismic features, such as strong seismic anisotropy, related to the properties of the main mineral MgSiO(3) postperovskite. But, after over a decade of investigations, the seismic observations still cannot be explained simply by flow models which assume dislocation creep in postperovskite. We have investigated the chemical diffusivity of perovskite and postperovskite phases by experiment and ab initio simulation, and derive equations for the observed anisotropic diffusion creep. There is excellent agreement between experiments and simulations for both phases in all of the chemical systems studied. Single-crystal diffusivity in postperovskite displays at least 3 orders of magnitude of anisotropy by experiment and simulation (D(a) = 1,000 D(b); D(b) ≈ D(c)) in zinc fluoride, and an even more extreme anisotropy is predicted (D(a) = 10,000 D(c); D(c) = 10,000 D(b)) in the natural MgSiO(3) system. Anisotropic chemical diffusivity results in anisotropic diffusion creep, texture generation, and a strain-weakening rheology. The results for MgSiO(3) postperovskite strongly imply that regions within the D″ region of Earth dominated by postperovskite will 1) be substantially weaker than regions dominated by perovskite and 2) develop a strain-induced crystallographic-preferred orientation with strain-weakening rheology. This leads to strain localization and the possibility to bring regions with significantly varying textures into close proximity by strain on narrow shear zones. Anisotropic diffusion creep therefore provides an attractive alternative explanation for the complexity in observed seismic anisotropy and the rapid lateral changes in seismic velocities in D″.

In this study, quartz, coesite, and stishovite were deformed concurrently with an olivine reference sample at high pressure and 850 ± 50 °C. Olivine deformed with an effective stress exponent (n) of 6.9 +3/-1, which we interpret to indicate that the Peierls creep deformation mechanism was active in the olivine. Quartz and coesite had very similar strengths and deformed by a mechanism with n = 2:8 +1.2/−0.9 and 2:9 +1.3/-0.9, respectively, which are consistent with previous measurements of power law creep in these phases. Stishovite deformed with n = 8.1 +3.7/-2.7 and was stronger than both olivine and the other silica polymorphs. The high stress exponent of stishovite is greater than that typically observed for power law creep, indicating it is probably (but not certainly) deforming by Peierls creep. The rheology of SiO2 minerals appears therefore to be strongly affected by the change in silicon coordination and density from fourfold in quartz and coesite to sixfold in stishovite. If the effect of Si coordination can be generalized, the increase in Si coordination (and density) associated with bridgmanite formation may explain the tenfold to 100‐fold viscosity increase around 660 km depth in the Earth.

The melting curve of Sn initially rises steeply as a function of pressure but exhibits a decrease in slope ($d{T}_{m}/dP$) above 40 GPa to become nearly flat above 50 GPa. Previous studies have argued that a body-centered tetragonal (bct) to cubic (bcc) phase transition occurs in this range at room temperature. However, our investigations have shown that the phase behavior is more complex in this region with orthorhombic (bco) splitting of reflections occurring in the x-ray diffraction pattern above 32 GPa and coexisting diffraction signatures of bco and bcc structures are observed between 40 and 70 GPa. Here we have documented the simultaneous presence of bco and bcc reflections up to the melting point, negating the possibility that their coexistence might indicate a kinetically hindered first-order phase transformation. In this paper we have extended the observation of Sn melting relations into the megabar ($Pg100$ GPa) range using the appearance of liquid diffuse scattering in x-ray diffraction patterns and discontinuities during thermal signal processing to diagnose the occurrence of melting. Both techniques yield consistent results that indicate the melting line maintains the same low slope up to the highest pressure examined and does not flatten. The results below approximately 40 GPa agree well with the melting relations produced recently using a multiphase equation of state fitted to available or assumed data. Above this pressure the experimental melting points lie increasingly below the predicted crystal-liquid phase boundary, but above the flat melting from past studies, indicating that the thermodynamic properties of the body-centered ``$\ensuremath{\gamma}$''-Sn structure remain to be clarified.

We use a combination of diamond anvil cell techniques and large volume (multi-anvil press, piston cylinder) devices to study the synthesis, structure and properties of new materials under high pressure conditions. The work often involves the study of structural and phase transformations occurring in the metastable regime, as we explore the phase space determined as a function of the pressure, temperature and chemical composition. The experimental studies are combined with first principles calculations and molecular dynamics simulations, as we determine the structures and properties of new phases and the nature of the transformations between them. Problems currently under investigation include structural studies of transition metal and main group nitrides, oxides and oxynitrides at high pressure, exploration of new solid-state compounds that are formed within the C-N-O system, polyamorphic low- to high-density transitions among amorphous semiconductors such as a-Si, and transformations into metastable forms of the element that occur when its "expanded" clathrate polymorph is compressed.

We investigated the high-P,T annealing and mechanical properties of nanocomposite materials with a highly nitrided bulk composition close to Ti3N4. Amorphous solids were precipitated from solution by ammonolysis of metal dialkylamide precursors followed by heating at 400–700 °C in flowing NH3 to produce reddish-brown amorphous/nanocrystalline materials. The precursors were then densified at 2 GPa and 200–700 °C to form monolithic ceramics. There was no evidence for N2 loss during the high-P,T treatment. Micro- and nanoindentation experiments indicate hardness values between 4–20 GPa for loads ranging between 0.005–3 N. Young's modulus values were measured to lie in the range 200–650 GPa. Palmqvist cracks determined from microindentation experiments indicate fracture toughness values between 2–4 MPa·m1/2 similar to Si3N4, SiC and Al2O3. Significant variations in the hardness may be associated with the distribution of amorphous/crystalline regions and the very fine grained nature (~3 nm grain sizes) of the crystalline component in these materials.

International audience; Sodium orthonitrate (Na3NO4) is an unusual phase containing the first example of isolated tetrahedrally bonded NO43- groups. This compound was obtained originally by heating together mixtures of Na2O and NaNO3 for periods extending up to > 14 days in evacuated chambers. Considering the negative volume change between reactants and products, it was inferred that a high-pressure synthesis route might favor the formation of the Na3NO4 compound. We found that the recovered sample is likely to be a high-pressure polymorph, containing NO43- groups as evidenced by Raman spectroscopy. The high-pressure behavior of Na3NO4 was studied using Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell above 60 GPa. We found no evidence for major structural transformations, even following laser heating experiments carried out at high pressure, although broadening of the Raman peaks could indicate the onset of disordering at higher pressure.

Several commercial titania photocatalyst powders were formed into thin (ca. 350 μm), 25 mm diameter ceramic wafers, sputter deposited with Pt on one side. The activities of each of the ceramic wafers were tested for hydrogen and oxygen evolution from aqueous sacrificial systems. The commercial sample PC50 (Millennium Chemicals, UK) yielded reproducible ceramic wafers with high activity for water photoreduction. Many of the ceramic wafers displayed low water photo-oxidation activities; however, these were greatly increased with addition of a NiO co-catalyst. In a selected case, hydrogen evolution activity was compared between a PC50 wafer and an identical weight of platinised PC50 powder suspension.

The remains of the first Iron Age chariot burial in Britain outside Yorkshire were discovered during the winter of 2000–1, near the Bronze Age burial mound of Huly Hill, at Newbridge, Edinburgh. Excavated by Headland Archaeology (UK) Ltd with the assistance of the National Museums Scotland, the chariot proved unique beyond just its burial location. The Newbridge chariot was buried intact, a method consistent with the burial practices of Continental Europe rather than Yorkshire, where they were predominantly buried disassembled. Detailed post-excavation analysis revealed a history of repair and reuse, and construction techniques that indicate links with the chariot building traditions of both Yorkshire and Continental Europe. Fifth centurybcradiocarbon dates for the burial place it firmly within La Tène A, consistent with its similarities to European examples and indicating that it pre-dates the known Yorkshire examples. This indicates the emergence of a British tradition of chariot construction by this time, familiar with Continental habits and technology but distinctively different in such areas as wheel construction and suspension fittings. Based on the findings, a reconstruction of the chariot was built for display in the National Museums Scotland, providing an opportunity further to understand and confirm the construction techniques observed or hypothesised during excavation.

ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth’s deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure (Cmcm; commonly referred to as the “post-perovskite” structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 (P63/mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 (P21/m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2S3 structure → P63/mmc structure. However, only the perovskite and CaIrO3 structures are stable with respect to dissociation into NaF and MgF2.

This article extends a welcome to, and outlines the development of, the British Association for the Study of Spirituality, including its links with the Journal for the Study of Spirituality.

A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1-2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C .

We have measured compressional wave velocity ( V P ) in talc as a function of temperature at 0.5 GPa. V P falls from 5.27±0.23 km s −1 at 25°C to 4.35±0.15 km s −1 at 800°C. Combining these results with a previously published bulk modulus ( K ) and δ K /δ P , gives a Poisson’s ratio ( ν ) of 0.268 and a shear modulus ( G ) of 22.6 GPa under atmospheric conditions. Assuming that ν is independent of temperature gives a δ K /δ T value of −19.3±0.64 MPa K −1 at 0.5 GPa. We used the experimental data, in combination with published data, to calculate bounds on the elastic moduli of a peridotite hydrated with talc just above cold subducting lithosphere. We find that an assemblage hydrated by only 0.9 wt% H 2 O has elastic wave velocities (calculated from the Voigt–Reuss–Hill average) lower than the anhydrous rock by an average of 7.6% for V P , and 9.7% for shear waves ( V s ) at 700°C. These results are consistent with observations of converted phase behavior in the vicinity of the surface of a cold subducting slab, and may place the low-velocity layer observed in the lowermost mantle wedge, not the uppermost slab as has previously been suggested.

L'A. d'abord decrit l'objet ou le contenu de l'experience religieuse, en choisissant les termes : le Sacre, le Saint et l'Humain comme symboles de realite et sens ultimes. Il depasse ensuite la description pour essayer d'entrer dans le processus de l'experience religieuse et propose trois types d'experience : le «pressenti» du Sacre, la «rencontre» dans le Saint et l'«engagement» pour l'Humain. Enfin il met en contexte l'application de ces types.

Something of the moral foundation of the Pluralism that is practiced in everyday life is captured in the series of interview responses and commentary. The commentary on the reported interviews speaks of the Self as "the primary, given, reality in the interviewees' worldview", and of its evaluation as "both human and sacred", and describes it as "the basis of a solidarity". Two experiences lay behind the conceptualization of "implicit religion" at the end of the 1960s. Intensive concerns with extensive effects give equal balance to both the focal points and to the hinterland being integrated. Thus it declines to call "religious" the occasional acclamation of a football team (or of a preacher), however passionate it may be, unless it epitomizes and/or affects personal or social life outside that hour of exposure. Keywords: commentary; implicit religion; pluralism; solidarity

The term “Implicit Religion” was (effectively) first coined in 1969, when it was adopted in preference to its predecessor, “secular religion.” The historical and ideological contexts of the concept will be sketched, before three definitions (or, better, “descriptions”) of the intended meaning are offered. Three studies, undertaken as test-cases for the utility of the concept, will be briefly reported, along with the subsequent development of study in the area of implicit religion, and its relationship with explicit religion and spirituality.

Application of pressure (1 GPa, 150 °C) enables the direct ion exchange of Cs+ for Na+ in both the alumino- and gallosilicate forms of natrolite, which does not occur at ambient pressure.

The simultaneous application of high pressure and high temperature has been used to achieve direct ion exchange of large cesium cations for the small sodium cations found in the zeolite natrolite by putting it into a superhydrated state with increased pore size. The larger cations remain trapped upon pressure release, and thus, this method is a means of producing new cationic forms of zeolites.

The title compound is synthesized in high yield by high-pressure reaction of a 3:1 mixture of Na2O and NaNO3 (4 GPa, 500 °C, 2 d).

Pressure and temperature are important environmental variables that influence living systems. However, while they vary over a considerable range on Earth and other planets, it has hardly been addressed how straightforwardly and to what extent cellular life can acquire resistance to extremes of these parameters within a defined genomic context and a limited number of generations. Nevertheless, this is a very pertinent question with respect to the penetration of life in allegedly inhospitable environments. In this study, directed evolution was used to reveal the potential of the nonsporulating and mesophilic model bacterium Escherichia coli to develop the ability to survive exposure to high temperature or pressure. While heat resistance could only marginally be increased, our data show that piezoresistance could readily and reproducibly be extended into the GPa range, thereby greatly exceeding the currently recognized maximum for growth or survival., IMPORTANCE While extremophilic microorganisms generally serve as the reference for microbial survival capacities in inhospitable environments, we set out to examine how readily a mesophilic model bacterium such as Escherichia coli could build up resistance to extremes of temperature or pressure within a very short evolutionary time scale. Both heat and high pressure constitute ecologically important physical stresses that are able to irrevocably penetrate the entire cell. Our results for the first time establish that cellular life can acquire resistance to pressures extending into the GPa range.

While an apprehension may sometimes seem unmediated, its conceptualisation cannot but be contextual. So, before turning to a more conceptual account of the idea in question, a sequence, indeed, a trio, of contingent memories that illuminate the setting, may facilitate the comprehension of the apprehension that was intended to be communicated by the conceptualisation of Implicit Religion. The first of the three stages was epitomised in, and came to a head in a "presenting" interpretation of, a particular discussion. "Commitment" has become the most commonly used of the three descriptions, then, that, almost from the start, have been offered as nearly synonymous with the concept of Implicit Religion. Once "religion" had been granted substance, then, as already indicated, it was a relatively short step to see its potential applicability, not only to the phenomenologically abhorrent, or to the ideologically irreligious, the blasphemous or truly "profane'. Keywords: Implicit Religion; trio

The solid solutions of $\ensuremath{\gamma}{\text{-Si}}_{3}{\text{N}}_{4}$ and $\ensuremath{\gamma}{\text{-Ge}}_{3}{\text{N}}_{4}$, $\ensuremath{\gamma}\text{\ensuremath{-}}{({\text{Ge}}_{x}{\text{Si}}_{1\ensuremath{-}x})}_{3}{\text{N}}_{4}$ with $x=0.000$, 0.178, 0.347, 0.524, 0.875, and 1.000, are studied. The band gap values of the solid solutions measured with soft x-ray spectroscopy have a range of $3.50--5.00\ifmmode\pm\else\textpm\fi{}0.20\text{ }\text{eV}$. The hardness values of these solid solutions estimated using an empirical relationship have a range of 22.2--36.0 GPa. We use the generalized gradient approximation of Perdew-Ernzerhof-Burke (GGA-PDE) within density functional theory and obtained a calculated band gap value range of 2.20--3.56 eV. The simulated N absorption and emission spectra agree very well with our measurements and the compositional trend among the calculated band gap values corresponds well with the measured values. The agreement between experimental and theoretical spectra indicates that Ge prefers the site with tetrahedral bonding symmetry. The band gap and hardness estimates have two approximately linear regimes, when $0\ensuremath{\le}x\ensuremath{\le}1/3$ and $1/3\ensuremath{\le}x\ensuremath{\le}1$. The band gap decreases as Ge replaces Si on octahedral sites and this suggests that the type of cation in the octahedral sites is mainly responsible for decreasing the band gap in these spinel nitrides. Our results indicate that solid solutions of $\ensuremath{\gamma}\text{\ensuremath{-}}{({\text{Ge}}_{x}{\text{Si}}_{1\ensuremath{-}x})}_{3}{\text{N}}_{4}$ provide a class of semiconductors with a tunable wide band gap suitable for UV laser or LED applications.

International audience; The graphitic layered compound C6N9H3.HCl was prepared by reaction between melamine and cyanuric chloride under high pressure–high temperature condition in a piston cylinder apparatus and characterised using SEM, powderX-ray diffraction, UV Raman and near-IR Fourier transform Raman spectroscopy with near-IR excitation. Theoretical calculations using density functional methods permitted evaluation of the mode of attachment of H atoms to nitrogen sites in the structure and a better understanding of the X-ray diffraction pattern. Broadening in the UV and near-IR FT Raman spectra indicate possible disordering of the void sites within the graphitic layers or it could be due to electron–phonon coupling effects.

The Editor of this journal shares personal reflections on ‘life with Implicit Religion’, these last 30 or 40 years.