Coquimbite, AlFe3+3(SO4)6(H2O)12⋅6H2O, was considered as a pure Fe3+ hydrated sulfate. However, previous mineralogical studies pointed out the occurrence of essential Al, occupying a distinct site in the crystal structure of this mineral. Through the critical re-examination of the available literature and new crystal-chemical data collected on a specimen from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, the chemical formula of coquimbite has been revised, taking into account the occurrence of Al. Coquimbite has a homeotypic relationship with paracoquimbite, Fe4(SO4)6(H2O)12⋅6H2O; both mineral species belong to the coquimbite group. On the contrary, aluminocoquimbite, Al2Fe2(SO4)6(H2O)12⋅6H2O, has a different topology and does not belong to that group.

Kaolinite and synthetic γ-Al(OH)3 (gibbsite or hydrargillite) were reacted with phenylphosphonic, phenylphosphinic and 2-nitrophenol-4-arsonic acids. The products were studied by powder X-ray diffraction, transmission electron microscopy/selected area electron diffraction/ energy dispersive X-ray/Fourier transform infrared and simultaneous thermogravimetric/differential thermal analysis. The acids were not intercalated but, instead, easily destroyed the structure of the minerals. Lamellar Al phenylphosphonate and aluminium phenylphosphinate and phenylarsonate with polymeric linear-chain structures were formed from kaolinite. The reaction between gibbsite and the same acids yielded almost identical products. No evidence of formation of grafted kaolinite derivatives after the reaction with phenylphosphonic acid was found.

Twenty nine Fe oxide concentrates of Thai soils formed on basalt, sandstone, shale/limestone and granite were investigated. Goethite and hematite are relatively more abundant in granitic and basaltic soils, respectively. Values of Feo/Fed range from 0.01 to 0.28 indicating that free Fe oxides are mostly crystalline.

There are no systematic differences in unit-cell dimensions for goethite and hematite in soils on different parent materials. Mean crystallite dimensions calculated from the 110 reflections are greater for hematite than for goethite. Aluminium substitution varies from 8 to 24 mole% for goethite and from 4 to 17 mole% for hematite. The dehydroxylation temperature for goethite ranges from 285ºC to 320ºC. The goethite in basaltic soils has a smaller crystal size and Al substitution, as well as a lower dehydroxylation temperature, compared to soils on other parent materials. The dehydroxylation temperature of goethite is positively related to Al substitution (R = +0.58), MCD110 (R = +0.49) and Ald (R = +0.53). The Mn, Ni, Cr, V and P in these soils occur in Fe oxides rather than as discrete minerals.

A synthetic analogue, Ca(Ti0.6Al0.2Ta0.16Nb0.04)OSiO4, of an aluminoan tantalian titanite previously described from Craveggia pegmatite (Piemonte, Italy) has been prepared by a ceramic synthesis technique and its crystal structure determined by Rietveld analysis of the powder X-ray diffraction pattern. The synthetic Al-Ta-Nb-rich titanite adopts space group A2/a implying that substitutions at the single octahedral site destroy the coherence of the off-centering of octahedral chains in the titanite structure resulting in a P 21/a → A2/a phase transition. Unit-cell dimensions obtained for the Al-Ta-Nb-rich titanite are: a = 7.0649(1) Å; b = 8.7187(1) Å; c = 6.5701(1) Å; β = 113.755(1)°, V = 370.41(1) Å3. The extensive replacement of Ti by Al, Ta and Nb results in a considerable decrease in the distortion of all coordination polyhedra in the structure of this titanite. These structural data suggest that a solid solution CaTi1-x(Alx /2 [Ta,Nb]x /2)OSiO4 (0 ≤ x ≤ 0.4) adopting the titanite structure might exist.

Warwickite constitutes about 5% of an outcrop of metamorphosed ultramafic rocks of Precambrian age in North-West Greenland. It occurs as slender grains, several millimetres long, and in anhedral grains up to 5 mm in size, together with forsterite, pleonaste, phlogopite, magnetite ± tourmaline. Post-metamorphic alteration of warwickite produced a network of boron-rich minerals and magnetite. The warwickite, containing up to 9.72% Al2O3, displays a significantly different chemical composition from warwickite elsewhere, such as that in recrystallized limestones from the type locality Warwick, New York, and in lamproitic and carbonatite-like rocks at Jumilla, Spain.

Euhedral crystals of complexly zoned niobian titanite (up to 0.3 mm) are enclosed in hedenbergite (Hd53—81Di15—43Jh3-5) and quartz from a hedenbergite vein skarn at Kamenne doly near Pisek, Czech Republic. They are associated with minor clinozoisite-epidote (Ps3—22), calcite, plagioclase (An95). scapolite (Me80—82), scheelite, pyrrhotite, fluorapatite, arsenopyrite, native bismuth and Bi,Te-minerals. The following textural and compositional subtypes were recognized: (I) Nb-rich titanite, (II) Nb-moderate titanite in the central zone, (III) Nb-poor, Sn-enriched titanite and (IV) Nb-poor, Al,F-rich titanite in the outer zone. The substitution Al(Nb,Ta)Ti—2 is dominant in subtypes I and II, the titanite subtype I being characterized by elevated contents of Al ≤ 0.257 atoms per formula unit (a.p.f.u.), Nb (≤ 0.161 a.p.f.u.) and Ta (≤ 0.037 a.p.f.u.). Amounts of Al, Nb and Ta in subtype II are smaller and more variable. The minor substitution SnTi—1 occurs chiefly in titanite subtype III with a content of Sn ≤ 0.039 a.p.f.u.. The substitution Al(F,OH)(TiO)_i is typical for titanite subtype IV exhibiting elevated contents of Al (s£ 0.221 a.p.f.u.), F (≤ 0.196 a.p.f.u.) and Fe (≤ 0.039 a.p.f.u.).

The negative relationship of substitutions Al(F,OH)(TiO)_i vs. SnTi—1 and Al(Nb,Ta)Ti—1 is constrained chiefly by crystal structure rather than by the composition of parent medium alone. Textural relations suggest that the Nb-moderate titanite in the core zone and entire outer zone are products of fluids-induced dissolution-reprecipitation processes. The studied niobian titanite represents a new F-enriched type from a medium-grade, calc-silicate rock.

Alunogen and meta-alunogen are the dominant phases present in transient sulphate efflorescences that are the latest products of the alteration of ignimbrite country rocks in the long-lived Te Kopia geothermal field. Meta-alunogen pseudomorphs alunogen and both species occur as white, fibrous, tangled masses, as prismatic, parallel growths, and as thin, platy, crystals, 8–15 μm across, that coalesce in an open cellular network. Small (<2 mm diam.) spherical aggregates of radiating, acicular halotrichite (Fe0.51Mg0.49Al2(SO4)4.22H2O), potash alum, mirabilite, melanterite and tschermigite are present locally. The cations needed to form these minerals derive from the host rocks with the exception of sulphur and ammonia that come from H2S and NH3 gases ascending with steam. The particular efflorescence assemblage reflects the prevailing conditions and ionic activities of a local micro-environment. Kaolinite formed by acid sulphate alteration is now being altered by steam to yield alunogen. In turn, alunogen can react with silica, or co-dissociate with silicic acid, to form kaolinite. The alternating dissolution and reprecipitation of kaolinite and alunogen moves aluminium in and through the surficial environment at Te Kopia.

Lizardite-1T crystals from Gew-graze at the Lizard, Cornwall, of an apparent composition (Mg2.94Fe0.03Al0.03)(Si1.97Al0.03)05(OH)4, have been observed to contain 2–5% of thin interstratifications of clinochlore when investigated by analytical transmission electron microscopy (TEM). The clinochlore is usually only a few unit layers thick but has an extensive lateral dimension parallel to the lizardite layers. Analytical TEM confirms the existence of very low-Al lizardite with a planar structure interstratified with occasional thin units of clinochlore containing substantial Al. Compositionally, such clinochlore (invisible by X-ray diffraction) interstratified throughout the lizardite crystals, could account for most of the Al present. We suggest that an occasional influx of Al causes the nucleation and growth of clinochlore at the expense of lizardite. The possibility of clinochlore contributing to the measured Al content in lizardite samples highlights the need for future investigations of Al-bearing serpentines to include careful examination and interpretation using imaging and analysis by TEM.

It has crept into serpentine discussions that lizardite cannot form without the coupled substitution of Al to relieve the misfit between the sheets of octahedra and tetrahedra. The lizardite at Gew-graze is almost Al-free, forms well-crystallized planar crystals and demonstrates that Al is not an essential element for lizardite crystallization.

An ‘Al-thermometer’ was applied to agate samples of volcanic parent rocks to provide information about the temperature of agate formation. The temperatures were calculated from concentrations of [AlO4]0 centres determined by electron paramagnetic resonance (EPR) measurements. The calculations for agate bands in some cases yield temperatures of up to 655°C, which are assumed to be invalid; they are thought to be artifacts resulting from non-equilibrium crystallization processes. In contrast, the formation temperatures (60–198°C) estimated for associated quartz incrustations within the agate geodes are in good accord with those calculated from oxygen isotope data. Direct estimation of the formation temperatures of agates is problematic. The best results will be obtained by analyses of associated phanerocrystalline quartz incrustations.

Crystals of laueite, Mn2+Fe23+(PO4)2(OH)2·8H2O, from the Cornelia mine open cut, Hagendorf Süd, Bavaria, are zoned due to aluminium incorporation at the iron sites, with analysed Al2O3 contents varying up to 11 wt.%. Synchrotron X-ray data were collected on two crystals with different Al contents and the structures refined. The laueite structure contains two independent Fe3+-containing sites; M2 and M3, which alternate in 7 Å corner-connected octahedral chains. The coordination polyhedra are different for the two sites, M2O4(OH)2 and M3O2(OH)2(H2O)2 respectively. The structure refinements show that Al preferentially orders into site M3. Refined site occupancies for M2 and M3 for the two crystals are: for crystal L-1, M2 = 0.70(1) Fe + 0.30(1) Al, M3 = 0.54(1) Fe + 0.46(1) Al and for crystal L-2, M2 = 0.67(1) Fe + 0.33(1) Al, M3 = 0.48(1) Fe + 0.52(1) Al. For crystal L-2, the octahedral chains have dominant Fe in M2, alternating with dominant Al in M3 along the chain, an ordering phenomenon not previously reported for laueite-related minerals.

The effects of punch geometry and sample size on forming limit diagrams in expansion are investigated in the case of a 2024 aluminium alloy. Four configurations were selected: flat punch (Marciniak test) or hemispheric punch and decimetric vs. centimetric tooling dimensions. Both decimetric and centimetric deep-drawing devices are associated with an image correlation tool that allows identifying without any contact the deformation on the surface of planar or non-planar specimens. Strains on the surface of the samples are observed by means of a double numerisation in three dimensions of the sample before and after deformation by using stereoscopic vision and triangulation. Finally, deep-drawing limit of the four configurations are compared in expansion state and with literature. Results mainly show that hemispherical punch allows measuring higher strains and is less sensitive to size effect than Marciniak test.

Aluminium is the most common metallic element, but has no known biological role. It accumulates in the body when protective gastrointestinal mechanisms are bypassed, renal function is impaired, or exposure is high – all of which apply frequently to preterm infants. Recognised clinical manifestations of aluminium toxicity include dementia, anaemia and bone disease. Parenteral nutrition (PN) solutions are liable to contamination with aluminium, particularly from acidic solutions in glass vials, notably calcium gluconate. When fed parenterally, infants retain >75% of the aluminium, with high serum, urine and tissue levels. Later health effects of neonatal intravenous aluminium exposure were investigated in a randomised trial comparing standard PN solutions with solutions specially sourced for low aluminium content. Preterm infants exposed for >10 d to standard solutions had impaired neurologic development at 18 months. At 13–15 years, subjects randomised to standard PN had lower lumbar spine bone mass; and, in non-randomised analyses, those with neonatal aluminium intake above the median had lower hip bone mass. Given the sizeable number of infants undergoing intensive care and still exposed to aluminium via PN, these findings have contemporary relevance. Until recently, little progress had been made on reducing aluminium exposure, and meeting Food and Drug Administration recommendations (<5 μg/kg per d) has been impossible in patients <50 kg using available products. Recent advice from the UK Medicines and Healthcare regulatory Authority that calcium gluconate in small volume glass containers should not be used for repeated treatment in children <18 years, including preparation of PN, is an important step towards addressing this problem.

Physiological dormancy of scarified seeds of Townsville stylo (Stylosanthes humilis HBK) was released by acidic aluminium (Al3+) solution. Antiethylenic substances inhibited germination of low-pH-stimulated dormant seeds, with a correspondingly low ethylene production and low activity of 1-aminocyclopropane-1-carboxylate (ACC) oxidase in seeds. On the other hand, antiethylenic substances did not decrease the germination of Al3+-stimulated seeds, but ACC oxidase activity and ethylene production by the seeds was decreased to a large extent. These data provide evidence that dormancy breakage by Al3+ differs from that caused by low pH and is not associated with ethylene production. Similarly to Al3+ action, methyl viologen (MV), a reactive oxygen species-generating compound, broke dormancy of Townsville stylo seeds. Sodium selenate and N-acetyl cysteine, antioxidant compounds, largely decreased germination of MV- and Al3+-stimulated dormant seeds. Altogether these data point to oxidative radicals constituting key molecules in the chain of events triggered by Al3+ leading to dormancy breakage.

Amounts of mineral nutrients and aluminium (Al) were assessed in the globoid inclusions, proteinaceous matrix and druse crystals of Eucalyptus calophylla seeds collected from trees grown in coal-mine (mean soil pH 4.3, Al 260 μg g−1) and forest soils (pH 5.3, Al 10 μg g−1). Energy-dispersive X-ray microanalysis (EDX) of bulk frozen hydrated samples indicated that significantly higher amounts of Mg, P, S, K and Ca occurred in the globoid inclusions of mine- than forest-site seeds. In both seedstocks, Al was detected in the globoid inclusions but not in the proteinaceous matrix or druse crystals. Significantly higher amounts of Al occurred in mine-site samples of dry and germinating seeds than in forest-site seeds. It was concluded that globoid inclusions may be useful as indicators of the soil conditions in which the parent plant was grown.

L'anisotropie des tôles d'aluminium est induite par le procédé de laminage, elle entraîne des défauts lors de l'opération de mise en forme de pièces par emboutissage. Le travail présenté dans cet article est une étude phénoménologique de cette anisotropie sur des tôles d'aluminium produites à SOCATRAL, au Cameroun. L'objectif est de mettre en évidence l'influence des différents paramètres en vue de mieux contrôler l'évolution de l'anisotropie. Au cours du laminage de l'aluminium, tous les paramètres susceptibles d'avoir une incidence sur la répartition des constituants insolubles dans le métal et sur la déformation des grains du métal ont un effet considérable sur l'anisotropie. Deux nuances d'aluminium (1200 et 1050) ont fait l'objet de cette étude pour laquelle tous les paramètres sont étudiés en utilisant une méthode statistique (SPC) à partir des banques de données de fabrication. Pour chaque paramètre identifié, les courbes de l'évolution de l'anisotropie sont présentées pour différentes épaisseurs de tôle. Les résultats obtenus permettront par la suite d'optimiser l'indice d'anisotropie afin de réduire les défauts à l'emboutissage.

The absorption of metal ions in the mammalian single-stomached gut is fortunately highly selective, and both luminal and tissue regulation occur. Initially, assimilation of metal ions in an available form is facilitated by the intestinal secretions, chiefly soluble mucus (mucin) that retards hydrolysis of ions such as Cu, Fe and Zn. Metal ions then bind and traverse the mucosally-adherent mucus layer with an efficiency M+ > M2+ > M3+. At the mucosa Fe3+ is probably uniquely reduced to Fe2+, and all divalent cations (including Fe2+) are transported by a membrane protein (such as divalent cation transporter 1) into the cell. This minimizes absorption of toxic trivalent metals (e.g. A13+). Intracellular metal-binding molecules (such as mobilferrin) may be present at the intracellular side of the apical membrane, anchored to a transmembrane protein such as an integrin complex. This mobilferrin would receive the metal ion from divalent cation transporter 1 and, with part of the integrin molecule, transport the metal to the cytosol for safe sequestration in a larger complex such as ferritin or‘paraferritin’. β2-Microglobulin and HFE (previously termed human leucocyte antigen H) may be involved in stabilizing metal mobilferrin-integrin to form this latter complex. Finally, a systemic metal-binding protein such as transferrin may enter the antiluminal (basolateral) side of the cell for binding of the sequestered metal ion and delivery to the circulation. Regulatory proteins, such as HFE, may determine the degree of ion transport from intestinal cells to the circulation. Gradients in pH and perhaps pCa or even pNa could allow the switching of ions between the different transporters throughout this mechanism.

Cet article porte sur la modélisation des culasses aluminium de moteurs diesel HDI en vue de prédire leur tenue en fatigue polycyclique. Celles-ci, avant d'être frettées, serrées sur le bloc moteur et utilisées en service, subissent un traitement thermique (trempe et revenu) afin d'améliorer leurs propriétés mécaniques. Lors de ce procédé d'importantes contraintes résiduelles sont générées. Leur modélisation est nécessaire pour obtenir des résultats numériques prédictifs. Une première difficulté vient de la modélisation des échanges thermiques. Pour cela, le choix d'une fonction analytique simple pour le coefficient d'échange H = f(Tparoi), suivi de l'optimisation des différents paramètres, a permis de modéliser les courbes de refroidissement. Une fois l'histoire thermique de la culasse modélisée, un calcul mécanique élastoplastique permet de déterminer les contraintes résiduelles. Celles-ci, fortement de traction dans la zone à risque, sont défavorables à la tenue à la fatigue polycyclique de la pièce dans le cas de la trempe à l'eau. La prise en compte de l'état résiduel de fin de traitement thermique dans la filière de dimensionnement à la fatigue polycyclique permet alors de caractériser les zones à risque expérimentalement observées.

The population of Stephanodiscus rotula in a temperate eutrophic lake was studied over a 2 month period (January to early March). Although during the study period nutrient concentrations in the lake water remained far in excess of phytoplankton requirements, no notable increase in chlorophyll levels was recorded. This suggests that algae were limited by shortage of light and low temperatures. Frequency distribution analysis of cell diameters showed a dramatic size reduction at the end of winter, followed by restoration of higher values by early spring. Electron probe X-ray microanalysis spectra from Stephanodiscus cells routinely showed peaks of Ca, K, Si, P, S, Fe, Al, Mn, Mg, Na and Cl, with substantial variation in elemental concentrations both between and within samples. End-of-winter reduction in the cell size coincided with a considerable depletion of intracellular chemical levels of Si, P, Cl and K and could be related to the concurrent decrease in dissolved organic C and increase in intracellular Al. Correlation and factor analysis of intracellular elemental concentrations showed that statistical elemental associations within Stephanodiscus cells were mainly determined by three factors, with P, Cl, Si and K showing higher loadings on the first, Ca, Mn and S on the second, and Fe, Ca and Al on the third factor. Significant correlations among the elements of the first association may indicate the importance of P (ATP), K (through involvement in P metabolism) and Cl (possibly charge balance) in the active Si uptake during the study period.