bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromite and chrome spinel occurrences from metacarbonates of the Oetztal–Stubai Complex (Northern Tyrol, Austria)
Authors: Mogessie A. , Purtscheller F. , Tessadri R.
Published: December 2006

Chromite inclusions in uvarovite-chrome garnet, chemically zoned chromite-chrome spinel and chrome spinel-olivine pairs from metacarbonates of the Oetztal-Stubai Complex (northern Tyrol, Austria) are described in terms of their textural occurrences and chemical compositions. Their genetic relationship in relation to the polymetamorphism of the region is discussed.
Phase relations in the system anorthite–potassium-feldspar at 10 kbar with emphasis on their solid solutions
Authors: Ai Y. , Green D. H.
Published: December 2006

Phase relations in the binary system anorthite-K-feldspar at 10 kbar were studied with a solid-media piston cylinder apparatus. The eutectic character of this system is confirmed, with the eutectic point located at An30Kf70 (± 3 mol%), and 1215 ± 15°C, 10 kbar. The mutual solubilities between anorthite and K-feldspar at the solidus are greatly increased at 10kbar compared with those at 1 atm. The maximum solubility of K-feldspar in anorthite is c. 5% at 1 atm, c. 18% at 10 kbar; and that of anorthite in K-feldspar is c. 3% at 1 atm, c. 7% at 10 kbar. The increased solubilities are attributed to the increase in the eutectic temperature at high isostatic pressures. The results imply increased ternary feldspar solid solutions at high pressures and support the existence of homogeneous feldspars with extensive ternary composition under high-P, T and anhydrous conditions.
Curvature of gypsum crystals induced by growth in the presence of impurities
Authors: Rinaudo Caterina , Franchini-Angela Marinella , Boistelle Roland
Published: December 2006

Gypsum crystals were grown at 25, 35, and 45 °C from solutions containing different ionic impurities (Mg2+, Na+, Cd2+). Curved gypsum crystals formed from the solutions enriched in magnesium or cadmium, whereas, in the presence of sodium, gypsum always grew undeformed. The mechanism of the curvature is described and an interpretation based on crystallographic considerations is given. Curvature is the result of impurity incorporation followed by crack formation and mechanical twinning which releases the internal stresses.
Genesis of the Pb–Zn deposit at Sant’Antonio di Val D’Aspra, Southern Tuscany (Italy): disparity between geo-petrographic data and fluid inclusion microthermometry
Authors: Giamello M. , Riccobono F. , Sabatini G.
Published: December 2006

The Pb–Zn deposit at Sant'Antonio di Val d'Aspra in the Farma Valley (Southern Tuscany) is hosted by Lower Moscovian carbonate rocks and shows many characters commonly found in Mississippi Valley type (MVT) deposits. Ore minerals (essentially sphalerite and galena) are closely confined to dolomitized portions of an only partly preserved black limestone. Mineralized carbonate rocks appear to have been eroded before the deposition of the overlying Upper Moscovian (Late Podolskian) shales. The diffuse presence of structures frequently found in internal sediments of karstic cavities indicates that supergene mechanisms have played an important role in the history of the deposit. A fluid inclusion study carried out on ore and gangue minerals revealed the presence of two different types of inclusions. The homogenization temperatures ranged from 120°C to 225°C but the most frequently found values were around 170°C. Salinity ranged from moderately low values up to 20 eq. wt. % NaCl. Lead isotopic composition rules out any relationship between the Sant'Antonio mineralization and Tertiary hydrothermal base metal occurrences in the same area. When all the data are taken together, a contrast is evident between geo-petrographic and isotopic data on the one hand, and fluid-inclusion microthermometry on the other.
The garnet-orthopyroxene Al barometer: problematic application to natural garnet lherzolite assemblages
Authors: Carswell D. A.
Published: December 2006

The garnet-orthopyroxene Al barometer specifically considers the Al content of orthopyroxene in equilibrium with garnet resulting from Mg-Tschermaks substitution. It is demonstrated that P-T calibrations of this barometer derived solely from experimental data for the MAS system, such as that favoured by Finnerty and Boyd (1984, 1987) based on the data of MacGregor (1974), cannot be expected to yield meaningful pressure estimates for natural garnet lherzolite assemblages. The presence of additional CaO, FeO and Cr2O3 components in natural garnet lherzolites can be expected to influence substantially the Al partitioning between orthopyroxene, garnet and/or spinel at any particular P and T. Thus a more comprehensive barometer formulation is required, such as the one provided by Nickel and Green (1985) that is based on experimental data for the CMAS and SMACCR systems with thermodynamic modelling and addition of an Fe correction term.

It is further emphasised that for orthopyroxenes in natural garnet lherzolites the amount of Al introduced as Mg-Tschermaks substitution cannot be assessed simply as the total Al cation content since such orthopyroxenes frequently contain Al cations linked to Na substitution in M2 sites or to Cr, Ti and possibly Fe3+ in M1 sites. Revised algorithms for the calculation of specific orthopyroxene contents are presented. Application to analytical data sets for garnet lherzolite zenolith suites in the Thaba Putsoa and Mothae kimberlites generates revised upper mantle P-T arrays which refute the widely accepted advocacy by Finnerty and Boyd (1984, 1987) and Finnerty (1989) of an upper-mantle palaeogeotherm beneath northern Lesotho that is markedly inflected to a higher thermal gradient at the depths of derivation of the more chemically fertile, porphyroclastic textured, xenoliths.
Kegelite: infrared spectroscopy and a structural hypothesis
Authors: Braithwaite R. S. W.
Published: December 2006

The infrared spectrum of kegelite has been measured and is discussed. The infrared spectra of 1 : 1 molar mixtures of leadhillite with pyrophyllite or with muscovite resemble the spectrum of kegelite, the chemical formula of which is a 1 : 1 stoichiometric sum of those of pyrophyllite and of the leadhillite polymorphs. Kegelite is not a physical mixture of these species, but its structure may be an interlayering of phyllosilicate and leadhillite-like structures within the unit cell. The unit cell parameters of pyrophyllite-1Tc and the leadhillite polymorphs are compatible with each other and can be combined to give a cell with parameters close to those of the kegelite cell. A structural model for kegelite on these bases is suggested, which is also consistent with its thermal analysis. The formula of kegelite can be written as Pb8(SO4)2(CO3)4(OH)4(AlOH)4(Si4O10)2.
Fluid inclusion study of tin-mineralized greisens and quartz veins in the Penouta apogranite (Orense, Spain)
Authors: Mangas J. , Arribas A.
Published: December 2006

The Penouta deposit is associated with a small Hercynian apogranite stock that intrudes Precambrian-Cambrian gneisses of the Ollo de Sapo Formation. Tin ore occurs as disseminations of cassiterite in the apogranite and as greisenized zones and quartz veins which traverse both the alkaline leucogranite and the surrounding metamorphic country rocks.

A fluid-inclusion study, utilizing microthermometric, crushing tests and Raman spectroscopic techniques on quartz from an intragranitic vein and a greisen of the host rock, indicates that the evolution of fluids was similar in both samples and occurred in the three main stages: The first stage is characterized by complex CO2 (CO2-N2-CH4-H2S) and complex CO2 aqueous (H2O-NaCl-CO2-N2-CH4-H2S) fluids of low salinity (Tm ice > −6°C), homogenization temperatures between 250 and 410°C homogenization pressures below 900 bars, and thermobarometric trapping conditions with temperatures below 700°C and pressures below 3250 bars. These fluids were probably responsible for the greisenization of the apogranite and wall rocks, and the precipitation of cassiterite. The second stage is represented by low-salinity aqueous solutions (H2O-NaCl) with Tm ice ⩾ −4.5°C, trapped at homogenization temperatures between 110 and 300 °C and homogenization pressures below 100 bars. This stage can be correlated with kaolinization. The third stage is characterized by higher salinity aqueous fluids (Tm ice ⩾ −16.5°C) containing Na+ and other cations, trapped at homogenization temperatures between 100 and 130°C and homogenization pressures below 5 bars. These fluids can be associated with the epigenetic or supergene phases of the orebody.
Coquandite, Sb6O8(SO4).H2O, a new mineral from Pereta, Tuscany, Italy, and two other localities
Authors: Sabelli C. , Orlandi P. , Vezzalini G.
Published: December 2006

Coaquandite, a new antimony oxy-sulphate hydrate, occurs as spheroidal knobs of silky fibres or, rarely, as tiny transparent colourless lamellar crystals on stibnite at the Pereta mine, Tuscany, Italy; it is associated with klebelsbergite, peretaite, valentinite, sulfur, gypsum, stibiconite, and senarmontite. Coquandite is triclinic P1, with a 11.434(7), b 29.77(4), c 11.314(4) Å, α 91.07(7)°, β 119.24(3)° γ 92.82(1)° . It has a cell volume of 3352(5)Å3 with Z = 12 and a calculated density of 5.78 g cm−3. The crystals, elongated along [001] and flattened on {010}, display polysynthetic twinning with (010) as the twin plane. Optically, they are biaxial (+) with z ≈ c, 2V ≫ 60° n = 2.08(5). The strongest lines of the X-ray powder pattern are [d in Å, (I), (hkl)] 14.84(50)(020), 9.27(41)(111, 110), 6.81(67)130, 3.304(93)(090), 3.092(100)(330).

Coquandite has also been found at the Cetine mine, Tuscany, Italy, and at the Lucky Knock mine, Tonasket, Okanogan County, Washington, USA. 22 microprobe chemical analyses (elemental microanalysis for H) gave Sb2O3 88.91, SO3 8.35, CaO 0.04, Na2O 0.03, H2O 1.43, total 98.76 wt.%, corresponding to the empirical formula (Sb + S = 7) Sb5.98Ca0.01Na0.01O7.96(SO4)1.02.0·78H2O, and to the idealised formula Sb6O8(SO4).H2O. The I.R. spectrum, which confirms the presence of water in the formula, is given.

A partial structural arrangement is also given: the Sb polyhedra lie in nine layers perpendicular to [010] and form 'hexagonally' shaped groups surrounded by SO4 tetrahedra.
Sulphide mylonites from the Renström VMS deposit, Northern Sweden
Authors: Duckworth Rowena C. , Rickard David
Published: December 2006

Sulphide mylonites are fine-grained massive sulphides which have deformed in a plastic manner. In the Renström Zn-Pb-Cu-Ag-Au VMS deposit, one of several operating mines in the Early Proterozoic Skellefte District in Northern Sweden, shear-zone metamorphism has resulted in the development of mylonitic fabrics within the sulphides. The massive sulphide ore is hosted in a shallow submarine to subaerial volcano-sedimentary sequence which has been variably metamorphosed and deformed. Initially, the sequence underwent burial metamorphism which was followed by an amphibolite grade regional metamorphic event at pressures of around 7.5 kbar and temperatures of 540-600°C This has been overprinted by a retrogressive metamorphic event at greenschist facies (at ca. 400°C with concomitant ductile deformation. Finally the area was uplifted to shallower crustal levels with associated cataclastic deformation.

Both the regional and dynamic metamorphic events have resulted in the development of specific textures in the sulphide ores. Textural evidence indicates that pressure solution has been mainly responsible for the plastic deformation in pyrite, while the weaker sulphide minerals such as pyrrhotite, chalcopyrite and galena have generally recrystallised in response to the high strains.

Sulphide mylonites are probably common rocks in many polydeformed massive sulphide deposits like Renström. They may have previously been misinterpreted as primary depositional textures.
New mineralogical data on uranophane and β-uranophane; synthesis of uranophane
Authors: Cesbron Fabien , Ildefonse Philippe , Sichere Marie-Claude
Published: December 2006

Uranyl-silicates are widespread minerals in oxidised parts of various uranium deposits, and they frequently contain associations of the polymorphic forms of uranophane. In several recent works devoted to the study of uranium deposits as natural analogues of high-level nuclear waste repository (HLNWR), uranophane is frequently mentioned but without determination of the exact polymorphic species. The existence of two polymorphs presenting different stabilities has to be taken into account when considering the long-term behaviour of these minerals and the use of thermodynamic models for predicting the radionuclide migration in HLNWR. We present here new crystallographic data on betauranophane, and preliminary results of synthesis experiments of uranyl silicates. XRD patterns and calculated parameters of beta-uranophane from a Mexican U-deposit are presented. Synthesis experiments succeeded in crystallising uranophane (alpha form) at different pH, Si-, Ca- and Na activities, but beta-uranophane was never obtained. The controlling physico-chemical parameters responsible for the occurrence of these two polymorphic forms are still unknown.
Asbecasite: crystal structure refinement and crystal chemistry
Authors: Sacerdoti Michele , Parodi Gian Carlo , Mottana Annibale , Maras Adriana , Ventura Giancarlo Della
Published: December 2006

The crystal structure of antimonian asbecasite in an ejectum of hypabyssal origin occurring at Tre Croci near Vetralla, Vico volcanic complex, Roman potassic province, Latium, Italy, has been refined to R = 0.042, and is compared to the original crystal structure determination carried out on the Sb-free asbecasite of hydrothermal metamorphic origin from the type-locality, Cherbandung in Binna valley, Monte Leone nappe, Switzerland. New electron microprobe analyses of samples from both localities demonstrate crystal-chemical features that permit distinction between asbecasites from the two occurrences, so far the only known localities for this mineral.
Iowaite, a re-investigation
Authors: Braithwaite R. S. W. , Dunn P. J. , Pritchard R. G. , Paar W. H.
Published: December 2006

Iowaite has been re-examined using new, well crystallized material from the Palabora open pit mine, Transvaal. Microprobe, carbon analyser and thermal analyses, powder and single-crystal X-ray diffraction, infrared, UV-visible and mass spectroscopic and optical studies were made. The ideal formula is (OH)16Cl2·4H2O. It is trigonal, R3̄m, a = 3.1183(9), c = 24.113(8) Å, V = 203.1(2) Å3, Z = 3/8; Dobs 2.09 g/cm3.; Dcalc 2.04 g/cm3; hardness (Mohs)=2 1/2. The interlayer Cl− ions are displaced from the threefold axis. It is uniaxial negative, with ω = 1.561 ± 0.002, ε = 1.543 ± 0.002; coloured crystals are intensely pleochroic, due to intervalence charge transfer between the Fe3+ and Fe2+ substituting for Mg2+, with O pale yellow, E deep blue-green.
Phase relations in the system PbS-PbSe-PbTe
Authors: Liu H. , Chang L. L. Y.
Published: December 2006

Phase relations in the system PbS-PbSe-PbTe were investigated in the temperature range between 1150 and 300°C. There is a complete solid solution series along the join PbS-PbSe, whereas miscibility gaps exist below ∼ 350°C and 805°C along joins PbSe-PbTe and PbS-PbTe, respectively. Both gaps extend into the ternary system, and the range of the gap between PbS and PbTe reduces in size with temperature as well as Se-content.

By using the subregular model of mixing (Ganguly and Saxena, 1987), mixing energetics and activity composition relations of PbXwere derived. The temperature-dependence of the interaction parameters was calculated to be 5057.6 − 1.7T, 9605.2 − 4.4T, 3933.2 − 3.1T(T< 500°C), 6410.3 − 6.35T(T< 500°C) 1649 − 0.26T, 1594.6 − 0.2T, and 12906.3 − 17.3Tfor WWSte, WTeS, WSeTe, WTeSe, WSSe, WSeS, and WSSeTe, respectively. A critical temperature along the join PbS-PbSe at ∼ 100°C was obtained from interaction parameter calculation, which suggests the separation of the PbS-PbSe series.

Correlation of solid-solution ranges established in this study with natural occurrences was made.
Wycheproofite: a new hydrated sodium aluminium zirconium phosphate from Wycheproof, Victoria, Australia, and a new occurrence of kosnarite
Authors: Birch William D. , Pring Allan , Bevan D. J. M. , Kharisun
Published: December 2006

Wycheproofite is a new hydrated sodium aluminium zirconium phosphate from a pegmatite vein in granite at Wycheproof, in northwestern Victoria, Australia. The mineral occurs as compact, finely fibrous masses in small cavities in the quartz/feldspar/muscovite/schorl-bearing pegmatite. The fibrous crystals are between 5 and 10 µm wide and up to several mm long. Accompanying minerals include two other zirconium phosphates — kosnarite and a new species, selwynite, the K-analogue of gainesite — as well as wardite, eosphorite, cyrilovite, leucophosphitc, rockbridgeite, a kidwellite-like mineral and saleeite. The wycheproofite aggregates are pale pinkish to brownish orange, with a vitreous to pearly lustre. The streak is colourless, fracture rough, cleavage not observed and the Mohs hardness is between 4 and 5. Optical data are incomplete due to the fibrous nature of the mineral; the indices of refraction are in the range 1.62–1.64. The measured density is 2.83 g cm−3. Chemical analysis gave (wt.%) Na2O 6.36, K2O 0.44, CaO 0.66, FeO 0.36, MnO 0.21, Al2O3 12.03, Cs2O 0.03, ZrO2 32.43, HfO2 1.24, P2O5 35.85, SiO2 0.23, F 0.34, H2O 9.0, less 0=F 0.14, Total 99.04. The simplified formula is NaAlZr(PO4)2(OH)2·H2O. Wycheproofite is triclinic with unit cell parameters a=10.926(5) Å, b = 10.986(5) Å, c = 12.479(9) Å, α= 71.37(4)°, β = 77.39(4)°, γ= 87.54(3)° V = 1375.9 Å3. For Z= 6, the calculated density is 2.81 g cm-3. The strongest lines in the X-ray powder diffraction pattern are [dobs (Å), Iobs,hkl] 2.603 (100) 040; 4.128 (80) 121; 3.711 (65) 023; 3.465 (60) 030; 8.865 (40) 101; 3.243 (35) 132. The crystal structure has not been solved due to the finely fibrous nature of the material available. The name is for the locality, which in the local Australian Aboriginal language means ‘witchie bushes growing on a hilltop’.

Data on the third occurrence of kosnarite, KZr2(PO4)3, at Wycheproof are also given.
Hydrogen bonding in borcarite, an unusual borate-carbonate mineral
Authors: Burns P. C. , Hawthorne F. C.
Published: December 2006

The crystal structure, including hydrogen positions, of borcarite, Ca4Mg[B4O6(OH)6](CO3)2, monoclinic, a = 17.840(4), b = 8.380(2), c = 4.445(1) Å, β = 102.04(3)°, V = 649.9(3) Å3, space group C2/m, has been refined by full-matrix least-squares methods to R = 2.5% and wR = 3.0% for 1020 unique observed [|F| ≥ 5σ(F)] reflections collected using Mo-Kα X-radiation. The H positions were located on difference-Fourier maps and were refined using the ‘soft’ constraint that O-H distances are ∼ 0.96 Å. The 4:4T FBB (fundamental building block) of the borcarite structure contains four Bϕ4 tetrahedra (ϕ = unspecified ligand) which share corners to form a four-membered polyhedral ring. Borcarite is the only mineral known to contain this FBB. The FBBs do not polymerize, but each shares three anions with an Mgϕ6 octahedron on either side, forming rods of composition [MgB4O6(OH)6]4- along the c-axis. The rigidity of these rods is enhanced by hydrogen bonding, and individual rods are connected through Caϕ8 polyhedra, Cϕ3 triangles and hydrogen bonds.
The formation of rhodochrosite–smithsonite (MnCO3–ZnCO3) solid-solutions at 5°C
Authors: Böttcher Michael E.
Published: December 2006

MnxZn(1−x)CO3 solid-solutions were prepared at 5°C by precipitation from metal-bearing bicarbonate solutions. The solids were identified by X-ray powder diffraction and infrared spectroscopy. Zn2+ ions substitute extensively for Mn2+ ions in the crystal lattice of anhydrous rhombohedral carbonates. Throughout the 24 h during which the experiments were conducted, the aqueous solutions remained undersaturated with respect to pure oxides, sulphates, hydroxides and hydroxysulphates. The solutions, however, were supersaturated with MnxZn(1−x)CO3 of any given composition. Besides the anhydrous rhombohedral carbonates, Zn4(OH)2(CO3)3·4H2O was precipitated from an aqueous solution with initially high Zn2+ concentration. The negative logarithm of the solubility product of Zn4(OH)2(CO3)3·4H2O was estimated theoretically to be 43.9 (25°C). Remaining saturation with respect to Zn4(OH)2(CO3)3·4H2O was calculated accordingly. The suggestion is made that hydrated zinc hydroxycarbonate is metastable under the experimental conditions used here, but that it should transform into anhydrous carbonates.
The low-temperature behaviour of analcime. 1: high-resolution neutron powder diffraction
Authors: Line C. M. B. , Dove M. T. , Knight K. S. , Winkler B.
Published: December 2006

The structure of a synthetic sample of analcime has been determined as a function of temperature between 30–300 K by high-resolution neutron powder diffraction. Although there are some reports of samples of analcime having non-cubic structures, the sample in our experiments remained cubic (space group la3d), and hence disordered, down to low temperatures. The absence of phase transitions involving ordering of the orientations of the water molecules, ordering of the sodium positions, or a displacive instability as in leucite and related materials, is discussed. We speculate that part of the reason for the absence of ordering of the water molecules or sodium cations is associated with the Al/Si disorder, which cannot order at low temperatures. We also discuss the likely distribution of the orientations of the water molecules at low temperatures, and propose that the water diads lie close to any of the crystal diads with the H-H Vectors lying close to the triads.
Mineral names applied to synthetic substances
Authors: Nickel Ernest H.
Published: December 2006

Guidelines on mineral nomenclature published by the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (Nickel and Mandarino, 1988) include the following statement: "If an artificial substance has been given a name, and a mineral corresponding to that substance is subsequently discovered, the name given to the artificial substance does not necessarily have to be applied to the mineral".
An ultrasonic probe for the extraction of microscopic quantities of minerals for X-ray work
Authors: Kovachev Veselin , Strashimirov Strashimir
Published: December 2006

The instrumentation and procedure is described for the extraction of very small and pure samples from polished mounts and thin sections of minerals, for X-ray analysis and other micro-analytical techniques. It uses a stand-mounted, tunable ultrasonic probe (400 W/15–50 kHz) inclined at 45°C to a microscope stage. The tip of the probe, usually a steel needle, is located on the desired mineral and an appropriate ultrasonic frequency is selected. Very fine powders are produced from grains as small as 0.01–0.005 mm. A distinct advantage of this technique is that, as different minerals powder at different rates and different frequencies, it is possible to separate a single mineral from an intergrowth of two or more minerals.
Minor elements in olivine from spinel lherzolite xenoliths: implications for thermobarometry
Authors: O'Reilly Suzanne Y. , Chen D. , Griffin W. L. , Ryan C. G.
Published: December 2006

The proton microprobe has been used to determine contents of Ca, Ti, Ni, Mn and Zn in the olivine of 54 spinel lherzolite xenoliths from Australian and Chinese basalts. These data are compared with proton-probe data for Ni, Mn and Zn in the olivine of 180 garnet peridotite xenoliths from African and Siberian kimberlites. Fe, Mn, Ni and Zn contents are well-correlated; because the spinel lherzolite olivines have higher mean Fe contents than garnet peridotite olivines (average Fo89.6vs. Fo90–92) they also have lower Ni and higher Mn contents. Zn and Fe are well-correlated in garnet peridotite olivine, but in spinel peridotites this relationship is perturbed by partitioning of Zn into spinel. None of these elements shows significant correlation with temperature. Consistent differences in trace-element contents of olivines in the two suites is interpreted as reflecting the greater degree of depletion of Archean garnet peridotites as compared to Phanerozoic spinel lherzolites. Ca and Ti contents of spinel-peridotite olivine are well correlated with one another, and with temperature as determined by several types of geothermometer. However, Ca contents are poorly correlated with pressure as determined by the Ca-in-olivine barometer of Köhler and Brey (1990). This reflects the strong T-dependence of this barometer: the uncertainty in pressure (calculated by this method) which is produced by the ±50°C uncertainty expected of any geothermometer is ca ± 8 kbar, corresponding to the entire width of the spinel-lherzolite field at 900–1200°C.
Techniques and methodology used in a mineralogical and osmium isotope study of platinum group minerals from alluvial deposits in Colombia, California, Oregon and Alaska
Authors: Lyon I. C. , Tamana H. , Vaughan D. J. , Criddle A. J. , Saxton J. M. , van Lierde P.
Published: December 2006

Platinum-group minerals (PGM) from placer deposits in Colombia, California, Oregon and Alaska were investigated with the electron microprobe, proton microprobe (μ-PIXE) and ion probe to analyse their major and trace element contents and 187Os/186Os isotopic ratios. Most of the grains in the samples investigated proved to be essentially homogeneous alloys of Pt-Fe and Os-Ir-Ru although a few of them contained inclusions of other PGM such as cooperite and laurite. Detailed analyses were undertaken on the Os-Ir-Ru alloy phases.

The 187Os/186Os isotope ratios fell into a range from 1.005 to 1.156 and are consistent with data published on PGM from other placer deposits from these regions. The ratios, together with the trace element data (and in particular the low rhenium content) determined by ion probe and μ-PIXE, indicate that crustal osmium was not incorporated in the grains and that no significant evolution of the 187Os/186Os ratios occurred during their history. These data, along with mineralogical and textural evidence, are consistent with a mantle origin for the grains through ultramafic intrusions, although the data do not entirely rule out alternative interpretations.
Digital analysis of X-ray films
Authors: Palmer David C.
Published: December 2006

High-resolution intensity profiles can be generated from X-ray diffraction films using a desk-top scanner and computer image analysis. The resulting intensity profiles have spatial resolutions equal to, or exceeding that of modern powder diffractometers — at a fraction of the cost. This technique provides an economical way of preserving the information stored in libraries of old (and deteriorating) powder diffraction films. The same technique can also be extended to permit quantitative analysis of single-crystal diffraction films.
An EXAFS study of the local structural environments of Fe, Co, Zn and Mg in natural and synthetic staurolites
Authors: Henderson C. M. B. , Charnock J. M. , Cressey G. , Griffen D. T.
Published: December 2006

X-ray absorption spectroscopy (XAS) has been used to study the local structures of Fe, Co, Zn, and Mg in synthetic and natural staurolites. Results for the near-edge features (XANES) and refined EXAFS were used to deduce the crystallographic site(s) occupied for each element. The least squares refined, mean first shell metal-O bond lengths, coordination numbers, and Debye-Waller factors are in the ranges: Fe 1.97–1.99 Å, 3.5–4.1, 0.013–0.023 Å2; Co 1.97–1.98 Å, 3.5–3.9, 0.009–0.014 Å2; Zn 1.95–1.96 Å, 3.7–3.8, 0.008–0.009 Å2; and Mn 1.99 Å, 3.8, 0.012 Å2. No significant differences were found which depended on element concentration or whether the sampes are synthetic or natural. The refined bond length for Mg in end-member Mg-staurolite is 2.00 Å but EXAFS data did not allow refinement to give reliable coordination number and Debye-Waller factor estimates. The EXAFS data, together with staurolite and model compound XANES features, suggest that > about 90% of Fe, Co, Zn and Mn are concentrated in the tetrahedral T2 site, while in Mg-staurolite > about 75% of the total Mg is in T2 with the remainder in octahedral sites. In natural staurolite from Pizzo Forno (PF2), a greater proportion of Mg appears to be in octahedral coordination.
A numerical approach for the formation of chlorite and sulphide-bearing greisen: a study based on the Navalcubilla system (Spanish Central System)
Authors: Tornos Fernando
Published: December 2006

The formation of sulphide and cassiterite-bearing chlorite-rich greisens in the Navalcubilla granite has been modelled theoretically. Numerical simulation on the reaction of a hydrothermal fluid with a granitic rock predicts assemblages very similar to those found in nature, with progressive formation of muscovite, quartz, chlorite, microcline and plagioclase zones. The hydrothermal alteration of the rock produces a neutralization of the inflowing acid fluid, a drop in the fS2 and, to a lesser degree, an increment in fO2. During hydrothermal alteration, fS2 and fO2 change abruptly between metasomatic zones, but chlorite seems to control their major changes. Scheelite and cassiterite are concentrated in the internal zones, while sulphides are related to the more external zones. Fluid-rock reactions seem to be very effective for precipitating cassiterite and scheelite, even from very Sn and W-poor fluids. Appreciable amounts of sulphides are only expected in systems with high concentrations of base metals. Boiling and simple cooling of the fluids acidifies and oxidizes them but chemical changes are not strong enough to induce significant precipitation of ore minerals, at least when the temperature changes are small. Continued circulation of fluids along fractures with previously precipitated quartz + wolframite produces replacement of wolframite by scheelite and sulphides.
Jarosite formation in weathered siliceous chalk in Fontevrault abbey, Loire Valley, France
Authors: Bauer Andreas , Velde Bruce
Published: December 2006

Jarosite, a hydrous potassium iron sulphate mineral, has been found as the product of weathering in a silicic chalk building stone of a 13th century abbey at Fontevrault (Maine-et-Loire, France). Destabilization of pyrite and glauconite dispersed in the calcareous stone results in the formation of jarosite. The alteration process is probably of very local origin, within the zone in the building stone at its surface where oxidation occurs during wetting and drying on a cyclical basis. The problem of the incompatibility of highly acidic solutions needed to stabilise jarosite (2.5 < pH) within the highly porous, calcareous silicate rock is not explained at present.
Vav proteins control MyD88-dependent oxidative burst
Authors: Miletic Ana V. , Graham Daniel B. , Montgrain Vivianne , Fujikawa Keiko , Kloeppel Tracie , Brim Karry , Weaver Brian , Schreiber Robert , Xavier Ramnik , Swat Wojciech
Published: December 2006

The importance of reactive oxygen intermediate (ROI) production in antimicrobial responses is demonstrated in human patients who suffer from chronic granulomatous disease (CGD) due to defective NADPH oxidase function. Exactly how bacterial products activating Toll-like receptors (TLRs) induce oxidative burst is unknown. Here, we identify the Vav family of Rho guanine nucleotide exchange factors (GEFs) as critical mediators of LPS-induced MyD88-dependent activation of Rac2, NADPH oxidase, and ROI production using mice deficient in Vav1, Vav2, and Vav3. Vav proteins are also required for p38 MAPK activation and for normal regulation of proinflammatory cytokine production, but not for other MyD88-controlled effector pathways such as those involving JNK, COX2, or iNOS and the production of reactive nitrogen intermediates (RNIs). Thus, our data indicate that Vav specifically transduces a subset of signals emanating from MyD88.
Endothelial Lu/BCAM glycoproteins are novel ligands for red blood cell α4β1integrin: role in adhesion of sickle red blood cells to endothelial cells
Authors: El Nemer Wassim , Wautier Marie-Paule , Rahuel Cécile , Gane Pierre , Hermand Patricia , Galactéros Frédéric , Wautier Jean-Luc , Cartron Jean-Pierre , Colin Yves , Le Van Kim Caroline
Published: December 2006

The Lutheran (Lu) blood group and basal cell adhesion molecule (BCAM) antigens are both carried by 2 glycoprotein isoforms of the immunoglobulin superfamily representing receptors for the laminin α5 chain. In addition to red blood cells, Lu/BCAM proteins are highly expressed in endothelial cells. Abnormal adhesion of red blood cells to the endothelium could potentially contribute to the vaso-occlusive episodes in sickle cell disease. Considering the presence of integrin consensus-binding sites in Lu/BCAM proteins, we investigated their potential interaction with integrin α4β1, the unique integrin expressed on immature circulating sickle red cells. Using cell adhesion assays under static and flow conditions, we demonstrated that integrin α4β1 expressed on transfected cells bound to chimeric Lu-Fc protein. We showed that epinephrine-stimulated sickle cells, but not control red cells, adhered to Lu-Fc via integrin α4β1 under flow conditions. Antibody-mediated activation of integrin α4β1 induced adhesion of sickle red cells to primary human umbilical vein endothelial cells; this adhesion was inhibited by soluble Lu-Fc and vascular cell adhesion molecule-1 (VCAM-1)–Fc proteins. This novel interaction between integrin α4β1 in sickle red cells and endothelial Lu/BCAM proteins could participate in sickle cell adhesion to endothelium and potentially play a role in vaso-occlusive episodes.
Hemolysis in sickle cell mice causes pulmonary hypertension due to global impairment in nitric oxide bioavailability
Authors: Hsu Lewis L. , Champion Hunter C. , Campbell-Lee Sally A. , Bivalacqua Trinity J. , Manci Elizabeth A. , Diwan Bhalchandra A. , Schimel Daniel M. , Cochard Audrey E. , Wang Xunde , Schechter Alan N. , Noguchi Constance T. , Gladwin Mark T.
Published: December 2006

Pulmonary hypertension is a highly prevalent complication of sickle cell disease and is a strong risk factor for early mortality. However, the pathophysiologic mechanisms leading to pulmonary vasculopathy remain unclear. Transgenic mice provide opportunities for mechanistic studies of vascular pathophysiology in an animal model. By microcardiac catheterization, all mice expressing exclusively human sickle hemoglobin had pulmonary hypertension, profound pulmonary and systemic endothelial dysfunction, and vascular instability characterized by diminished responses to authentic nitric oxide (NO), NO donors, and endothelium-dependent vasodilators and enhanced responses to vasoconstrictors. However, endothelium-independent vasodilation in sickle mice was normal. Mechanisms of vasculopathy in sickle mice involve global dysregulation of the NO axis: impaired constitutive nitric oxide synthase activity (NOS) with loss of endothelial NOS (eNOS) dimerization, increased NO scavenging by plasma hemoglobin and superoxide, increased arginase activity, and depleted intravascular nitrite reserves. Light microscopy and computed tomography revealed no plexogenic arterial remodeling or thrombi/emboli. Transplanting sickle marrow into wild-type mice conferred the same phenotype, and similar pathobiology was observed in a nonsickle mouse model of acute alloimmune hemolysis. Although the time course is shorter than typical pulmonary hypertension in human sickle cell disease, these results demonstrate that hemolytic anemia is sufficient to produce endothelial dysfunction and global dysregulation of NO.
Thromboxane receptor blockade improves the antiatherogenic effect of thromboxane A2 suppression in LDLR KO mice
Authors: Cyrus Tillmann , Yao Yuemang , Ding Tao , Dogné Jean Michel , Praticò Domenico
Published: December 2006

Suppression of thromboxane (Tx) A2 biosynthesis retards atherogenesis. In this setting, the coincidental presence of nonconventional ligands for the TxA2 receptor (TP), such as isoprostanes, could still induce a proatherogenic vascular phenotype. However, no data are available on the effect of combining suppression of TxA2 formation with blockade of TP in atherogenesis. To this end, we tested the effect of a selective COX-1 inhibitor, SC560, a TP antagonist, BM-573, or a combination of both in low-density lipoprotein receptor-deficient mice on a high-fat diet. None of the treatments affected body weight or plasma cholesterol or triglycerides levels. Although SC-560 suppressed TxA2 biosynthesis, BM-573 reduced its levels by 35%; in contrast, the 2 drugs, alone or in combination, did not significantly affect prostacyclin levels. At the end of the study, SC560 and BM-573 reduced atherogenesis; however, a further significant decrease was observed in mice receiving both drugs. This effect was associated with a further significant reduction of vascular inflammation, a decrease in macrophages, and an increase in the content of collagen and smooth muscle cells of the atherosclerotic lesions. These results show for the first time that the addition of a TP antagonist increases the antiatherogenic effect of COX-1–dependent TxA2 suppression.
Penumbra encodes a novel tetraspanin that is highly expressed in erythroid progenitors and promotes effective erythropoiesis
Authors: Heikens Marc J. , Cao Thai M. , Morita Chikako , DeHart Sarah L. , Tsai Schickwann
Published: December 2006

In a search for new genes involved in the regulation of erythropoiesis, we identified murine Penumbra cDNA from a multipotent hematopoietic cell line based on its predominant expression in erythroblasts. Subsequently, we identified the human PENUMBRA from a bone marrow cDNA library. Penumbra is a new member of the tetraspanin superfamily of membrane proteins, many of which are thought to function as organizers of supramolecular signaling complexes. Human and murine Penumbras contain 283 amino acids and are 97% identical. The human PENUMBRA gene is mapped to chromosome 7q32, a hot spot for deletions in myelodysplastic syndromes and acute myelogenous leukemias. Penumbra is targeted to the cell surface and forms disulfide-bonded homodimers. To study the effects of Penumbra deletions, we created a knockout mouse model by gene targeting. Penumbra−/− mice develop massive splenomegaly, basophilic macrocytic red blood cells, and anemia as they age. A multipotent hematopoietic cell line, EMX, was established from the bone marrow of a Penumbra−/− mouse. EMX exhibits ineffective erythropoiesis in the presence of erythropoietin, a defect that is reversed by reexpression of Penumbra. These findings indicate that Penumbra has a positive function in erythropoiesis and its deletion or mutation may result in anemia.
MafB negatively regulates RANKL-mediated osteoclast differentiation
Authors: Kim Kabsun , Kim Jung Ha , Lee Junwon , Jin Hye Mi , Kook Hyun , Kim Kyung Keun , Lee Soo Young , Kim Nacksung
Published: December 2006

Receptor activator of nuclear factor κB ligand (RANKL) induces osteoclast formation from hematopoietic cells via regulation of various transcription factors. Here, we show that MafB negatively regulates RANKL-induced osteoclast differentiation. Expression levels of MafB are significantly reduced by RANKL during osteoclastogenesis. Overexpression of MafB in bone marrow-derived monocyte/macrophage lineage cells (BMMs) inhibits the formation of TRAP+ multinuclear osteoclasts, but phagocytic activity of BMMs is retained. Furthermore, overexpression of MafB in BMMs attenuates the gene induction of NFATc1 and osteoclast-associated receptor (OSCAR) during RANKL-mediated osteoclastogenesis. In addition, MafB proteins interfere with the DNA-binding ability of c-Fos, Mitf, and NFATc1, inhibiting their transactivation of NFATc1 and OSCAR. Furthermore, reduced expression of MafB by RNAi enhances osteoclastogenesis and increases expression of NFATc1 and OSCAR. Taken together, our results suggest that MafB can act as an important modulator of RANKL-mediated osteoclastogenesis.
Serotonin provides an accessory signal to enhance T-cell activation by signaling through the 5-HT7 receptor
Authors: León-Ponte, Matilde , Ahern Gerard P. , O'Connell Peta J.
Published: December 2006

Although typically considered a neurotransmitter, there is substantial evidence that serotonin (5-HT) plays an important role in the pathogenesis of inflammatory disorders. Despite these findings, the precise role of 5-HT in modulating immune function, particularly T-cell function, remains elusive. We report that naive T cells predominantly express the type 7 5-HT receptor (5-HTR), and expression of this protein is substantially enhanced on T-cell activation. In addition, T-cell activation leads to expression of the 5-HT1B and 5-HT2A receptors. Significantly, exogenous 5-HT induces rapid phosphorylation of extracellular signal-regulated kinase-1 and -2 (ERK1/2) and IκBα in naive T cells. 5-HT–induced activation of ERK1/2 and NFκB is inhibited by preincubation with a specific 5-HT7 receptor antagonist. Thus, 5-HT signaling via the 5-HT7 receptor may contribute to early T-cell activation. In turn, 5-HT synthesized by T cells may act as an autocrine factor. Consistent with this hypothesis, we found that inhibition of 5-HT synthesis with parachlorophenylalanine (PCPA) impairs T-cell activation and proliferation. Combined, these data demonstrate a fundamental role for 5-HT as an intrinsic cofactor in T-cell activation and function and suggest an alternative mechanism through which immune function may be regulated by indoleamine 2,3-dioxygenase–mediated catabolism of tryptophan.
A review of interventions triggered by hepatitis A infected food-handlers in Canada
Authors: Tricco Andrea C , Pham Ba' , Duval Bernard , De Serres Gaston , Gilca Vladimir , Vrbova Linda , Anonychuk Andrea , Krahn Murray , Moher David
Published: December 2006

Background

In countries with low hepatitis A (HA) endemicity, infected food handlers are the source of most reported foodborne outbreaks. In Canada, accessible data repositories of infected food handler incidents are not available. We undertook a systematic review of such incidents to evaluate the extent of viral transmission through food contamination and the scope of post-exposure prophylaxis (PEP) interventions.

Methods

A systematic search of MEDLINE and EMBASE was conducted to identify published reports of incidents in Canada. An expanded search of a news repository (i.e., transcripts from newspapers and newscasts) was also conducted to identify the location and timing of an incident, which was used to retrieve the related report by contacting local public health departments. Data pertaining to case identification, public health risk, PEP interventions, and associated costs was independently abstracted by two reviewers and summarized according to incidents with and without large PEP interventions.

Results

A total of 16 incidents were identified from 1998–2004. There were approximately 3 incidents requiring public notification per year. Only 12.5% of incidents were described in published reports, indicating that published data significantly underestimated the number of incidents and PEP interventions. Data pertaining to the remaining incidents was unpublished, sparse and highly dispersed at the local public health level.

Six of the 16 incidents required large PEP interventions to immunize on average 5000 potentially exposed individuals. Secondary transmission was low. Characteristics of incidents requiring large PEP interventions included potentially infectious food handlers working with uncooked food for a prolonged duration in high-volume grocery stores in high-density urban areas.

Conclusion

Infected food handlers with hepatitis A virus (HAV) requiring public notification are not infrequent in Canada. Published data severely underestimated the burden of PEP intervention. Better and consistent reporting at the local and national level as well as a national data repository should be considered for the management of future incidents.
Tumor cell invasion of collagen matrices requires coordinate lipid agonist-induced G-protein and membrane-type matrix metalloproteinase-1-dependent signaling
Authors: Fisher Kevin E , Pop Andreia , Koh Wonshill , Anthis Nicholas J , Saunders W Brian , Davis George E
Published: December 2006

Background

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid signaling molecules implicated in tumor dissemination. Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a membrane-tethered collagenase thought to be involved in tumor invasion via extracellular matrix degradation. In this study, we investigated the molecular requirements for LPA- and S1P-regulated tumor cell migration in two dimensions (2D) and invasion of three-dimensional (3D) collagen matrices and, in particular, evaluated the role of MT1-MMP in this process.

Results

LPA stimulated while S1P inhibited migration of most tumor lines in Boyden chamber assays. Conversely, HT1080 fibrosarcoma cells migrated in response to both lipids. HT1080 cells also markedly invaded 3D collagen matrices (~700 μm over 48 hours) in response to either lipid. siRNA targeting of LPA1 and Rac1, or S1P1, Rac1, and Cdc42 specifically inhibited LPA- or S1P-induced HT1080 invasion, respectively. Analysis of LPA-induced HT1080 motility on 2D substrates vs. 3D matrices revealed that synthetic MMP inhibitors markedly reduced the distance (~125 μm vs. ~45 μm) and velocity of invasion (~0.09 μm/min vs. ~0.03 μm/min) only when cells navigated 3D matrices signifying a role for MMPs exclusively in invasion. Additionally, tissue inhibitors of metalloproteinases (TIMPs)-2, -3, and -4, but not TIMP-1, blocked lipid agonist-induced invasion indicating a role for membrane-type (MT)-MMPs. Furthermore, MT1-MMP expression in several tumor lines directly correlated with LPA-induced invasion. HEK293s, which neither express MT1-MMP nor invade in the presence of LPA, were transfected with MT1-MMP cDNA, and subsequently invaded in response to LPA. When HT1080 cells were seeded on top of or within collagen matrices, siRNA targeting of MT1-MMP, but not other MMPs, inhibited lipid agonist-induced invasion establishing a requisite role for MT1-MMP in this process.

Conclusion

LPA is a fundamental regulator of MT1-MMP-dependent tumor cell invasion of 3D collagen matrices. In contrast, S1P appears to act as an inhibitory stimulus in most cases, while stimulating only select tumor lines. MT1-MMP is required only when tumor cells navigate 3D barriers and not when cells migrate on 2D substrata. We demonstrate that tumor cells require coordinate regulation of LPA/S1P receptors and Rho GTPases to migrate, and additionally, require MT1-MMP in order to invade collagen matrices during neoplastic progression.