bluuebunny/crossref_metadata_2025 huggingface dataset:
Compositional Variation of pyroxene and mica from the Little Murun ultrapotassic complex, Aldan Shield, Russia
Authors: Mitchell Roger H. , Vladykin Nikolai V.
Published: December 2006

Pyroxene and mica found in plutonic rocks of the Little Murun ultrapotassic pluton exhibit trends of compositional evolution that permit evaluation of the differentiation sequence of the complex. Pyroxene evolves from diopside in kalsilite and phlogopite pyroxenites through aegirine-diopside in shonkinite to aegirine in late stage charoitite and evolved hypabyssal rocks. The compositional trend is unusual in that the hedenbergite content of the pyroxenes never exceeds 15 mol.% and is thus unlike pyroxene compositional trends found in sodic alkaline complexes. Mica is Al- and Ti-poor and ranges in composition from Fe-rich phlogopite through biotite towards tetraferriannite. Compositional trends of mica found in ‘lamproite-like’ hypabyssal rocks are identical to those observed in the micaceous plutonic rocks; hence the former are considered to be representatives of the lamprophyric facies of the magmas which formed the plutonic series.
Sericitization of plagioclase in the Rosses Granite Complex, Co. Donegal, Ireland
Authors: Que Meideno , Allen Alistair R.
Published: December 2006

Sericitization in three separate pulses of the Rosses Granite Ring Complex, Co. Donegal, Ireland, has been investigated texturally and chemically using electron microscopy, electron microprobe and fluid inclusion thermometry. The sericitization, which is restricted to the cores of plagioclase, is associated with pores which are abundant in the cores, but absent in the margins. Alkali feldspar, although porous, is unaltered. Associated with the sericitization is alteration of the adjacent primary plagioclase within the cores of grains to a more sodic composition.

It is postulated that the sericitization resulted from the action of externally derived secondary hydrothermal fluids, which gained access to the pores in the plagioclase via now sealed microfractures, formed either by contraction during cooling of the Rosses Complex, or more likely by hydraulic fracturing by the fluids themselves. Limited fluid/rock ratios restricted the degree of sericitization within the host plagioclase, whilst an absence of alteration in alkali feldspar may have been due to the inaccessibility of pores in the alkali feldspar to the hydrothermal fluids at the time of alteration. Fluid inclusion data suggest that the fluids were of low salinity, and that the sericitization took place at an early stage in the cooling history of the Rosses Complex at temperatures between 400 and 600°C. It is further contended that greisenization in the Rosses Complex predated the sericitization and that the greisenization may have been due solely to volatile-rich late-stage magmatic fluids.
Thermal expansion of cancrinite
Authors: Hassan Ishmael
Published: December 2006

Thermal expansion coefficients were measured for a cancrinite from Bancroft, Ontario, Canada. Measurements of cell parameters and unit-cell volumes were obtained at room temperature and at heating intervals of 50°C over the temperature range from 50 to 1400°C. The unit-cell parameters for cancrinite increase non-linearly with temperature up to 1200°C and shortly thereafter, the mineral melted. The c parameter increases more rapidly than the a parameter, and the c/a ratio increases linearly with temperature. A plausible thermal expansion mechanism for cancrinite, which is based on the framework expansion that occurs as a function of cavity content, is presented. In the thermal expansion of cancrinite, the short Na-H2O in the H2O-Na—H2O chain expands to form equal distances to the two H2O molecules in the chain. This causes the Na atoms to move towards the plane of the six-membered rings and forces the tetrahedra to rotate and the rings become more planar. The Na atoms then form bonds to all six (O1 and O2) oxygen atoms in a ring; the Na-O1 bonds become shorter and the Na-O2 bonds become longer. These effects cause an increase in both a and c, and thus an increase in the c/a ratio. A similar thermal expansion mechanism operates in the sodalite-group minerals where the six-membered rings and Na-Cl bond are involved.
Experimental simulation of the formation of fibrous veins by localised dissolution-precipitation creep
Authors: Bons Paul D. , Jessell Mark W.
Published: December 2006

Fibrous veins are generally interpreted in terms of the crack-seal mechanism. Several aspects of fibrous veins (fibrous structure, curved fibres, symmetry of antitaxial veins) are however better explained by vein formation without fracturing. Mass transfer to such veins would be by diffusional transport rather than by fluid flow through the veins. Deformation by dissolution-precipitation creep can provide the driving force for the necessary mass transfer. Veins form when mass transfer is heterogeneous and precipitation is localised.

Experiments were performed which enforced a chemical potential gradient, acting as the driving force for diffusional mass transfer. These experiments resulted in fibrous growths in aggregates of soluble salts (NaCl and KCl) saturated with brine. The experimental results support the theory that fibrous veins may form without fracturing and that rather than providing evidence for major fluid pathways, fibrous veins may instead represent localised precipitation during diffusional material transfer.
The crystal chemistry of the solid solution series between chalcostibite (CuSbS2) and emplectite (CuBiS2)
Authors: Razmara M. F. , Henderson C. M. B. , Pattrick R. A. D. , Bell A. M. T. , Charnock J. M.
Published: December 2006

Sulphosalts in the system CuSbS2-CuBiS2(chalcostibite-emplectite) form a complete solid solution series. Seven compositions with the general formula Cu(SbxBi1–x)S2have been synthesized using dry methods at 310°C. All members of the series are orthorhombic (space groupPnma) and show smoothly increasingaandbcell parameters with substitution of Bi for Sb; theccell parameter increases up to 50% CuBiS2substitution and then becomes constant. DSC experiments on CuBiS2show an endothermic heat effect (2.45 kJ/mol.) at 472°C due to the breakdown reaction to Cu3BiS3(wittichenite) plus Bi2S3(bismuthinite). With the addition of 10% CuSbS2to CuBiS2, the decomposition temperature increases and the endothermic peak is broadened but the energy remains essentially the same (2.53 kJ/mol.). No evidence of this decomposition was observed when the amount of the CuSbS2component was >30%. The local structure and co-ordination of Cu in the samples were studied by EXAFS analysis of the Cu-Kedge but no significant variation occurs in the local Cu environment. The Debye-Waller factor for the first shell of S atoms surrounding Cu in end member CuSbS2tends to be slightly smaller than for the intermediate solid solutions, suggesting that the tetrahedral Cu environments in the intermediate composition samples is somewhat more disordered than in the end-member. The low expansion characteristics alongcappear to be controlled by the linkages between the (CuS3+ BiS2) sheets perpendicular tocbeing relatively inflexible.
Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland
Authors: Coulson Ian M.
Published: December 2006

The North Qôroq centre comprises a series of nested nepheline syenite intrusions and forms part of the mid-late Proterozoic Gardar province of South Greenland. Within the centre fractionation has produced varied rock types ranging from augite-syenite to lujavrite, a eudialyte microsyenite. Samples of eudialyte from the lujavrites of unit SN1B of the centre show evidence for two-stage alteration. This alteration ranges from slight modification along crystal margins to complete breakdown and replacement by new pseudomorphing phases. Modification to crystal margins is accompanied by increasing Nb and Zr contents and is related to metasomatism produced by the intrusion of younger syenite units of the North Qôroq centre. More extensive alteration is as a result of metasomatism followed by lower-temperature supergene alteration. Simplified reactions for this breakdown include eudialyte + metasomatic fluid = allanite + nepheline; eudialyte + metasomatic fluid = titanite + aegirine + møsandrite + wöhlerite; eudialyte + fluid = zirfesite + fluid. Mass balance calculations for altered compared with unaltered samples of lujavrite show that alteration took place at approximately constant volume with an overall increase in Fe (+2.41 g/100g), Si and K (+0.65 and +0.61 g/100g), whilst Na (−2.67 g/100g) and all trace elements, particularly La, Y, Nb and Zr (−5.6 to −166 g/10000g) are lost from the system.
The crystal structure of kintoreite, PbFe3(PO4)2(OH,H2O)6
Authors: Kharisu  , Taylor M. R. , Bevan D. J. M. , Pring A.
Published: December 2006

The crystal structure of kintoreite, PbFe3(PO4)2(OH,H2O)6, has been refined. The mineral is rhombohedral, Rm with a = 7.3310(7), c = 16.885(2) Å, Z = 3; the structure has been refined to R = 3.0% and Rw = 3.0% using 183 observed reflections [I > 2σ(I)]. Kintoreite has the alunite-type structure which consists of sheets of corner-sharing Fe(O,OH)6 octahedra parallel to (001). The sheets are composed of clusters of three corner-linked octahedra which are tilted so that the three apical O atoms form the base of the XO4 tetrahedra. The clusters of octahedra are linked to similar groups by corner-sharing to form six membered rings. The Pb cations occupy the cavities between pairs of octahedral sheets and are surrounded by six oxygen atoms from the tetrahedra and six oxygen atoms from the octahedra to form a very distorted icosahedron. The mean bond lengths for the various coordination polyhedra are X–O 1.55 Å, (X= P, As, S); Fe–(O, OH) 2.01 Å; Pb–O 2.84 Å. The composition of the crystal used in the refinement was PbFe3(PO4)1.3(AsO4)0.4(SO4)0.3(OH,H2O)6. The XO4 anions are disordered, as in beudantite, rather than being ordered, as they are claimed to be in corkite.
Juabite, Cu5(Te6+O4)2(As5+O4)2.3H2O. a new mineral species from the Centennial Eureka mine, Juab County, Utah
Authors: Roberts Andrew C. , Gault Robert A. , Jensen Martin C. , Criddle Alan J. , Moffatx Elizabeth A.
Published: December 2006

Juabite, ideally Cu5(Te6+O4)2(As5+O4)2·3H2O, is triclinic, space-group choices P1(1) or P(2), with unit-cell parameters refined from powder data: a = 8.984(5), b = 10.079(7), c = 8.975(5) Å, α = 102.68(7)°, β = 92.45(6)°, γ = 70.45(5)° V = 746.8(8) Å3, a:b:c = 0.8914:1:0.8905, Z = 2. The strongest seven reflections of the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 9.28 (70)(010), 4.65 (70)(020), 3.097 (100)(030,11), 3.018 (60)(212), 2.658 (50)(01), 2.468 (50)(2) and 1.740 (50)(1, 521, 5). The mineral is an extremely rare constituent on the dumps of the Centennial Eureka mine, Juab County, Utah, U.S.A., where it occurs as crystalline platy masses that average 0.2–0.3 mm in longest dimension within small interconnected vugs of drusy quartz. Associated minerals are enargite, beudantite, and an undefined, possible Pb-analogue of arsenobismite. Individual crystals are subhedral to euhedral and average 125 × 100 × 1–2 µm in size. Cleavage {010} perfect. Forms are: {010} major; {100}, {01}, and {101} minor. The mineral is translucent (masses) to transparent (crystals), emerald-green, with a pale green streak, and an uneven to subconchoidal fracture. Juabite is vitreous to adamantine (almost gemmy) on cleavage faces, brittle, and nonfluorescent; H (Mohs) 3–4; D (calc.) 4.59 g/cm3 for the idealised formula. In polished section, juabite is white in plane-polarised reflected light in air with ubiquitous turquoise-blue internal reflections; bireflectance and anisotropy are unknown (due to interference from internal reflections). Averaged electronmicroprobe analyses yielded CuO 38.25, PbO 0.57, TeO3 32.58, As2O5 22.81, H2O (calc. assuming 3H2O) [5.19], total [99.40] wt.%, leading to the empirical formula (Cu5.01Pb0.03)Σ5.04(TeO4)l.93(AsO4)2.07·3.00H2O based on O = 19. The infrared absorption spectrum shows definite bands for structural H2O with an O-H stretching frequency centred at 3283 cm−1 and a H-O-H flexing frequency centred at 1642 cm−1. The mineral name is for the county within the state of Utah in which the Centennial Eureka mine is located.
Mineralogy and mineral chemistry of oxide-facies manganese ores of the Postmasburg manganese field, South Africa
Authors: Gutzmer J. , Beukes N. J.
Published: December 2006

The diagenetic to very low-grade metamorphic manganese ores of the Postmasburg manganese field provide a unique example of oxide-facies manganese ores in a Palaeoproterozoic palaeokarst setting. The ores are composed mainly of braunite group minerals, including braunite, partridgeite and bixbyite, with rare braunite II and Ca-poor, silica-depleted braunite. Iron-poor partridgeite is distinguished from Fe-rich bixbyite and the occurrence of Ca-poor, silica-depleted braunite is reported for the first time. Braunite and partridgeite formed during early diagenesis but remained stable under greenschist facies metamorphic conditions. In contrast, bixbyite is apparently a product of metasomatic remobilisation under peak metamorphic conditions. It is suggested that local variations of the metamorphic mineral association reflect variations of the host rock composition and that they are not related to changing P-T conditions of metamorphic alteration, a model promoted by previous authors. The phase chemistry of braunite, braunite II and bixbyite is explained by the existing polysomatic stacking model for the braunite group. However, the chemical composition of partridgeite and Ca-poor, silica-depleted braunite can only be explained by introducing a distinct module layer, with partridgeite composition, to the existing polysomatic stacking model.
Bismuth and bismuth–antimony sulphosalts from Neogene vein mineralisation, Baia Borşa area, Maramureş, Romania
Authors: Cook Nigel J.
Published: December 2006

Several complex Cu-Pb-Bi, Cu-Pb-Bi-Sb and Ag-Pb-Bi sulphosalt minerals have been identified in samples from hydrothermal vein mineralisation associated with the Toroiaga sub-volcanic body in the Baia Borşa area of Maramureş County, northwest Romania. This is the first chemically-documented report of Bi-sulphosalts in the Neogene metallogenic province around Baia Mare. The investigated samples contain abundant amounts of matildite solid solution within galena, the Cu-Pb/Bi sulphosalts aikinite, friedrichite, krupkaite, hammarite, lindströmite and gladite as well as nuffieldite and berryite. Within the Ag-Pb/Bi group, the majority of analysed grains can be regarded as members of the lillianite homologous series. Three distinct lillianite homologues were identified, which correspond to (i) phases along the lillianite-gustavite solid solution join (Pb3Bi2S6-AgPbBi3S6), (ii) phases within solid solution field of heyrovskyite, and (iii) compositions which best correspond to ‘schirmerite’,sensuMakovicky and Karup-Møller (1977b), but may represent disordered gustavite, vikingite or eskimoite. Some of the analysed lillianite homologues contain excess Cu, which may occupy interstitial sites. Furthermore, a large proportion of the lillianite homologues display significant substitution of Sb for Bi within the limits predicted by experimental investigations. Cosalite, also showing a range of compositions including Sb-rich varieties is recognised. Izoklakeite, Cu2Pb22(Sb,Bi)22S57, is an abundant phase throughout the analysed samples, its composition is in good agreement with previously published analyses, except for excess Cu and Fe beyond the limits previously reported. The description of several minerals from this new occurrence and compositional data on them, including the Sb-bearing varieties, provides valuable additional information on compositional limits in natural samples.
Cation and vacancy distribution in an artificially oxidized natural spinel
Authors: Menegazzo Giorgio , Carbonin Susanna , Giusta Antonio Della
Published: December 2006

During research on the influence of temperature on cation partitioning in natural Mg-Al-Fe2+-Fe3+spinels, some crystals were accidentally oxidized during heat treatment. The oxidation product, studied by means of single-crystal X-ray diffraction, turned out to be a phase retaining theFd3mparent spinel structure, but with cell edgeaand oxygen coordinateuconsiderably smaller than the parent ones (a∼ 8.087 as compared with ∼ 8.111 Å;u∼ 0.2609vs.0.2617–0.2636) and with vacant sites due to oxidation.

Assuming that the oxidation process must occur due to the addition of oxygen to the crystal boundary as cations are being preserved and rising in total valence, the site population was determined and compared with that of untreated and heated samples. It was found that, on oxidation, a charge enrichment in the tetrahedral site T had occurred, this phenomenon following that observed during heating at increasing temperatures also in other spinel series. This continuity was always in the direction of an increase in random charge distribution. Cation vacancies produced during oxidation were restricted to the octahedral site M.

Examination of bulk sections by reflected light microscopy showed a few hematite lamellae as inclusions in the oxidized samples, not detectable by microprobe analysis or single-crystal structural refinement. However, hematite played a marginal part in oxidation. Vacancy-oxygen distances in oxidized spinels were determined from experimental data in the literature.
The crystal structure of averievite, Cu5O2(VO4)2.nMX: comparison with related compounds
Authors: Starova G. L. , Krivovlchev S. V. , Fundamensky V. S. , Filatov S. K.
Published: December 2006

The crystal structure of averievite, Cu5O2(VO4)2·nMX has been determined. Trigonal system, space group P3, a = 6.375(1), c = 8.399(1) Å, V = 295.6(1) Å3, Z = 1, Dx = 4.01(1) g/cm3. The atomic arrangement is characterized by infinite nets parallel to (001) composed of [OCu4]6+ tetrahedra linked via corners in hexagonal rings. The bases of neigbouring tetrahedra are in one plane and their non-shared corners are turned to the opposite sides. The [VO4]3− tetrahedra are attached to the bases of [OCu4] tetrahedra. There are large (R >3.2 Å) channels in the structure where large molecular particles can enter. The comparison of the averievite structure with related compounds (in particular, copper oxovanadates) is given from the point of view of [OT4] polyion crystal chemistry.
Ba-rich celestine: new data and crystal structure refinement
Authors: Brigatti M. F. , Galli E. , Medici L.
Published: December 2006

A Ba-rich celestine (Sr0.87Ba0.13SO4) filling cavities of volcanoclastic rocks from Montecchio Maggiore (Vicenza, Italy) was studied. The role of the Ba content in the mineral was determined using X-ray powder data, single crystal X-ray refinement, thermal and chemical analyses. The unit cell parameters (obtained by single crystal diffraction) are a = 8.408, b = 5.372, c = 6.897 Å, and the refinement in the space group Pnma (Z = 4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 Å and agrees with an occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculations confirm that all twelve interactions are significant and define an irregular array around the cation.
The agpaitic rocks - an overview
Authors: Sørensen Henning
Published: December 2006

It is now generally agreed that the term ‘agpaitic’ should be restricted to peralkaline nepheline syenites (and phonolites) containing minerals such as eudialyte and rinkite, that is complex silicates of Zr, Ti, the rare earth elements (REE), and F and other volatiles. There are, however, cases of transition into more common types of nepheline syenites containing zircon, titanite, ilmenite, etc.

The agpaitic rocks are characterized by extremely high contents of rare elements such as Li, Be, Nb, Ta, REE, Zr, Th, etc. and of volatiles, first of all F and Cl. This gives rise to a wealth of mineral species, more than 500 in the Lovozero and Khibina complexes of the Kola peninsula, about 250 in Mont Saint-Hilaire, Quebec, Canada, and about 200 in the type locality, the Ilímaussaq complex, South Greenland.

These rocks have very long melting intervals and solidus temperatures as low as 500 to 400°C. They are accompanied by a gas phase rich in methane and other hydrocarbons and most probably also by sodium-rich fluids as indicated by the presence of minerals such as ussingite (NaAlSi3O8·NaOH) and villiaumite (NaF) and of pegmatites and hydrothermal veins rich in sodium and rare and volatile elements.

Agpaitic nepheline syenites are considered to have been formed by consolidation of melts oversaturated in alkalis, especially sodium, under conditions preventing the volatiles from escaping. These melts have been derived by extreme fractionation processes in alkali basaltic or nephelinitic magmas. The main stage of crystallization of the melts is characterized by minerals such as nepheline (sometimes also sodalite), alkali feldspars, arfvedsonite, aegirine and eudialyte, but the most highly developed, hyperagpaitic lujavrites of the Ilímaussaq complex have been formed from melts with extreme concentrations of sodium and volatiles resulting in the formation of naujakasite instead of nepheline, ussingite instead of sodalite and alkali feldspars, and steenstrupine instead of eudialyte. During the late stages of crystallization, sodium-rich fluids are the cause of late- and postmagmatic alteration and of the formation of hydrothermal mineralizations. The late stages are characterized by water-soluble sodium-rich minerals of which more than 80 have been found in the Khibina and Lovozero complexes.
Weathering of ultramafic rocks and element mobility at Mt. Prinzera, Northern Apennines, Italy
Authors: Venturelli Giampiero , Contini Simona , Bonazzi Achille , Mangia Alessandro
Published: December 2006

The weathering of the Mt. Prinzera serpentinites (Parma province, Northern Apennines, Italy) produced dominant smectite and minor Fe-hydroxides. The mobility of the elements during weathering has been estimated using the ratio Ki = MiS/MiR, where Mi indicates the mass of a generic component i before (R) and after (S) the weathering, and using TiO2 as a practically immobile component. For prevalently to tendentially mobile elements, the degree of mobility, which in our case increases as Ki decreases, is in the order Mn ≈ Cr = Fe < V ≈ Zn ≈ Co < Ni < Si < Mg < Ca. The elements Ti, Ga, Al and Zr are prevalently immobile. The mass chemically removed by the circulating waters during weathering may reach very high values (on average 52% of the original mass of serpentinite) and the main contribution to the mass loss is due to Si and Mg. The composition of the perennial and ephemeral springs in the area is in agreement with the degree of the element mobility at least for Cr, Mg and Ca.
Carbonate-carbonate immiscibility, neighborite and potassium iron sulphide in Oldoinyo Lengai natrocarbonatite
Authors: Mitchell Roger H.
Published: December 2006

Porphyritic natrocarbonatite lavas erupted from the Oldoinyo Lengai volcano (Tanzania) on 17 October 1995 and 15–19 December 1995 differ from previously studied lavas in that they preserve textures indicative of groundmass carbonate-carbonate immiscibility. The immiscible fractions are considered to involve: a Na-K-Ca-CO2-Cl-rich, F-bearing fluid crystallizing gregoryite, sodian sylvite, potassium neighborite as well as a complex Ba-rich carbonate; and a Na-rich, Cl-poor carbonate liquid approximating to a nyerereite-gregoryite cotectic composition. Compositional data are given for potassium neighborite, this mineral being the first recognized occurrence of a fluorine-based perovskite group mineral in a magmatic environment. New compositional data are also given for a previously recognized potassium iron sulphide which indicate that this phase is probably a solid solution between the ternary sulphides, KFe3S4, K2Fe3S4, and KFe2S3. Textural and paragenetic data are interpreted to suggest that these recent lavas are more evolved than previously investigated Oldoinyo Lengai lavas and that natrocarbonatite is a highly evolved rather than a primitive magma.
On Li-bearing micas: estimating Li from electron microprobe analyses and an improved diagram for graphical representation
Authors: Tischendorf Gerhard , Gottesmann Bärbel , Förster Hans-Jürgen , Trumbull Robert B.
Published: December 2006

Lithium may constitute an essential element in micas, yet it cannot be detected by the electron microprobe. Since Li is critical for correctly classifying micas and properly calculating their formulae, several methods have been proposed to overcome this analytical deficiency. We offer empirical relationships between Li2O and SiO2, MgO, F, and Rb in trioctahedral micas, and between Li2O and F as well as Rb in dioctahedral micas. The resultant regression equations enable lithium contents to be sufficiently well estimated from EPM analyses within the range of validity discussed.

Secondly, we introduce an easy to handle, new diagram with the axis variables [Mg-Li] and [Fetot + Mn + Ti-AlVI] for graphical representation and discuss its scientific rationale. Being based on absolute abundances of cations in the octahedral layer, the diagram provides a simple means to classify micas in terms of composition and octahedral site occupancy, and it also allows compositional relationships between Li-bearing and Li-free mica varieties as well as between trioctahedral and dioctahedral micas to be displayed on a single, two-dimensional diagram.
Platinum-group element sulpharsenides and Pd bismuthotellurides in the metamorphosed Ni-Cu deposit at Las Aguilas (Province of San Luis, Argentina)
Authors: Gervilla Fernando , Sáncnez-Anguita Alejandro , Acevedo Rogelio D. , Hach-Ali Purificación Fenoll , Paniagua Andres
Published: December 2006

The Las Aguilas Ni-Cu-PGE deposit is associated with a sequence of basic-ultrabasic rocks made up of dunite, harzurgite, norite and amphibolite. These igneous (partially metamorphosed) rocks, and their host granulites, gneisses and migmatites of probable Precambrian age, are highly folded. The sulphide ore, consisting of pyrrhotite, pentlandite and chalcopyrite, occurs in the cores of both antiform and synform structures, within dunite, harzburgite and mainly along shear zones in bronzitite, replacing small mylonitic subgrains. The platinum-group mineral assemblage is dominated by Pd bismuthotellurides (Pt-free merenskyite, palladian bismuthian melonite and michenerite), with minor sperrylite, and PGE-sulpharsenides. The latter often occur as single, zoned crystals frequently showing cores of irarsite; outside these are concentric zones of cobaltian hollingworthite, rhodian nickelian cobaltite and Fe-rich nickelian cobaltite.

Mineralogical, textural and chemical evidence indicate that the sperrylite and platinum-group element sulpharsenides were formed during a primary magmatic event associated with the fractionation of a basaltic melt, which was contaminated by the assimilation of metamorphic crustal rocks. PGE sulpharsenides crystallized from As-bearing, residual magmatic liquids that collected PGE and segregated after the crystallization of the monosulfide solid solution. During high-grade metamorphism, sulpharsenides were remobilized as solid crystals in the liquated sulfides suffering partial dissolution and fracturing. On the other hand, there is no evidence of a primary concentration of Pd-bismuthotelluride minerals, and their present spatial distribution is only the consequence of their formation under high- to medium-grade metamorphism, down to temperatures of below 500°C. Pd bismuthotellurides crystallize even in fractures of sulpharsenides, attached to the boundaries of highly dissolved sulpharsenide crystals, and intergrown with molybdenite.
Essential role of the TNF-TNFR2 cognate interaction in mouse dendritic cell–natural killer cell crosstalk
Authors: Xu Jun , Chakrabarti Ayan K. , Tan Jennifer L. , Ge Lisheng , Gambotto Andrea , Vujanovic Nikola L.
Published: December 2006

Dendritic cells (DCs) and natural killer (NK) cells are essential components of the innate immune system and have a central role in initiation and regulation of adaptive immune responses. During the early critical immune activities, DCs and NK cells interact and reciprocally regulate each other via cell-cell contact. The molecular mediators of the DC–NK-cell crosstalk are largely undefined. In the present study, we show in mice that DC stimulation of NK-cell IFN-γ secretion requires DC membranebound but not secreted products; is increased by augmenting the expression of DC transmembrane tumor necrosis factor (tmTNF) and NK-cell transmembrane TNF receptor type 2 (tmTNFR2); is inhibited by blocking TNF or TNFR2 but not TNFR1; is impaired by knocking out DC Tnf or NK-cell Tnfr2 but not DC Tnfr1 or Tnfr2 and NK-cell Tnf or Tnfr1; and is restored in TNF-deficient DCs by reconstituting tmTNF, but cannot be mimicked by soluble TNF. We also demonstrate that DC TNF and NK-cell TNFR2 are required for DC-mediated NK-cell proliferation and amplification of cytotoxic activity. These novel findings provide the first evidence that DC–NK-cell crosstalk mediates enhancement of NK-cell functions via triggering NK-cell tmTNFR2 by DC tmTNF.
Modulation of tryptophan catabolism by human leukemic cells results in the conversion of CD25− into CD25+ T regulatory cells
Authors: Curti Antonio , Pandolfi Simona , Valzasina Barbara , Aluigi Michela , Isidori Alessandro , Ferri Elisa , Salvestrini Valentina , Bonanno Giuseppina , Rutella Sergio , Durelli Ilaria , Horenstein Alberto L. , Fiore Francesca , Massaia Massimo , Colombo Mario P. , Baccarani Michele , Lemoli Roberto M.
Published: December 2006

Indoleamine 2,3-dioxygenase (IDO) is a novel immunosuppressive agent expressed in some subsets of normal and neoplastic cells, including acute myeloid leukemia (AML) cells. Here, we show that IDO expression correlates with increased circulating CD4+CD25+FOXP3+ T cells in patients with AML at diagnosis. In vitro, IDO+ AML cells increase the number of CD4+ CD25+ T cells expressing surface CTLA-4 and FOXP3 mRNA, and this effect is completely abrogated by the IDO inhibitor, 1-methyl tryptophan (1-MT). Purified CD4+CD25+ T cells obtained from coculture with IDO+ AML cells act as T regulatory (Treg) cells because they do not proliferate, do not produce interleukin (IL)–2, and inhibit naive T-cell proliferation. Coculture with IDO+AML cells results in the conversion of CD4+CD25− into CD4+CD25+ T cells, which is completely abrogated by 1-MT. Moreover, in mice, intrasplenic injection of IDO+ leukemia/lymphoma A20 cells induces the expansion of bona fide Treg cells by conversion of CD4+CD25− T cells; this effect is counteracted by 1-MT treatment. These data indicate that AML cells induce T-cell tolerance by directly converting CD4+CD25− T cells into CD4+CD25+ Treg cells through an IDO-dependent mechanism.
Differential growth factor regulation of aspartyl-(asparaginyl)-β-hydroxylase family genes in SH-Sy5y human neuroblastoma cells
Authors: Lahousse Stephanie A , Carter Jade J , Xu Xaolai J , Wands Jack R , de la Monte Suzanne M
Published: December 2006

Background

Aspartyl (asparaginyl)-β-hydroxylase (AAH) hydroxylates Asp and Asn residues within EGF-like domains of Notch and Jagged, which mediate cell motility and differentiation. This study examines the expression, regulation and function of AAH, and its related transcripts, Humbug and Junctin, which lack catalytic domains, using SH-Sy5y neuroblastoma cells.

Results

Real time quantitative RT-PCR demonstrated 8- or 9-fold higher levels of Humbug than AAH and Junctin, and lower levels of all 3 transcripts in normal human brains compared with neuroblastic tumor cells. AAH and Humbug expression were significantly increased in response to insulin and IGF-I stimulation, and these effects were associated with increased directional motility. However, over-expression of AAH and not Humbug significantly increased motility. Treatment with chemical inhibitors of Akt, Erk MAPK, or cyclin-dependent kinase 5 (Cdk-5) significantly reduced IGF-I stimulated AAH and Humbug expression and motility relative to vehicle-treated control cells. In addition, significantly increased AAH and Humbug expression and directional motility were observed in cells co-transfected with Cdk-5 plus its p35 or p25 regulatory partner. Further studies demonstrated that activated Cdk-5 mediated its stimulatory effects on AAH through Erk MAPK and PI3 kinase.

Conclusion

AAH and Humbug are over-expressed in SH-Sy5y neuroblastoma cells, and their mRNAs are regulated by insulin/IGF-1 signaling through Erk MAPK, PI3 kinase-Akt, and Cdk-5, which are known mediators of cell migration. Although AAH and Humbug share regulatory signaling pathways, AAH and not Humbug mediates directional motility in SH-Sy5y neuroblastoma cells.
A role for Phospholipase D in Drosophilaembryonic cellularization
Authors: LaLonde Mary , Janssens Hilde , Yun Suyong , Crosby Juan , Redina Olga , Olive Virginie , Altshuller Yelena M , Choi Seok-Yong , Du Guangwei , Gergen J Peter , Frohman Michael A
Published: December 2006

Background

Cellularization of the Drosophila embryo is an unusually synchronous form of cytokinesis in which polarized membrane extension proceeds in part through incorporation of new membrane via fusion of apically-translocated Golgi-derived vesicles.

Results

We describe here involvement of the signaling enzyme Phospholipase D (Pld) in regulation of this developmental step. Functional analysis using gene targeting revealed that cellularization is hindered by the loss of Pld, resulting frequently in early embryonic developmental arrest. Mechanistically, chronic Pld deficiency causes abnormal Golgi structure and secretory vesicle trafficking.

Conclusion

Our results suggest that Pld functions to promote trafficking of Golgi-derived fusion-competent vesicles during cellularization.
Irregular breakfast eating and health status among adolescents in Taiwan
Authors: Yang Rea-Jeng , Wang Edward K , Hsieh Yeu-Sheng , Chen Mei-Yen
Published: December 2006

Background

Regular breakfast eating (RBE) is an important contributor to a healthy lifestyle and health status. The aims of the present study were to evaluate the relationships among irregular breakfast eating (IRBE), health status, and health promoting behavior (HPB) for Taiwanese adolescents.

Methods

A cross-sectional, descriptive design was used to investigate a cluster sample of 1609 (7th -12th grade) adolescents located in the metropolitan Tao-Yuan area during the 2005 academic year. The main variables comprised breakfast eating pattern, body weight, and health promoting behaviors. Data were collected by a self-administered questionnaire.

Results

A total of 1609 participants were studied, 64.1% in junior high school and 35.9% in high school, boys (47.1%) and girls (52.9%) ranging in age from 12–20 years. Of the total participant population, 28.8% were overweight and nearly one quarter (23.6%) reported eating breakfast irregularly during schooldays. The findings indicated that adolescents with RBE had a lower risk of overweight (OR for IRBE vs. RBE = 1.51, 95% CI: 1.12, 2.04), and that the odds of becoming overweight were 51% greater for IRBE than for RBE even after controlling for demographical and HPB variables. IRBE also was a strong indicator for HPB. However, the profile of the high-risk IRBE group was predominantly junior high schoolchildren and/or children living without both parents.

Conclusion

This study provides valuable information about irregular breakfast eating among adolescents, which is associated with being overweight and with a low frequency of health promoting behavior. School and family health promotion strategies should be used to encourage all adolescents to eat breakfast regularly.
Pulmonary sarcoidosis associated with psoriasis vulgaris: coincidental occurrence or causal association? Case report
Authors: Nikolopoulou Melita , Katsenos Stamatis , Psathakis Kostas , Rallis Efstathios , Sampaziotis Dimitrios , Panagou Panagiotis , Tsintiris Kostas , Bouros Demosthenes
Published: December 2006

Background

Sarcoidosis is rarely associated with a distinct disease. One disease infrequently associated with sarcoidosis is psoriasis.

Case presentation

This case study describes a 38-year-old male, who presented with chest pain, high-grade fever, arthralgias and a skin rash accompanied by bilateral hilar lymphadenopathy on his chest radiograph. Extensive investigations including fiber-optic bronchoscopy with bronchoalveolar lavage and labial and skin biopsies, demonstrated that two distinct clinical entities co-existed in the same patient: pulmonary sarcoidosis and psoriasis vulgaris. Combination therapy for both diseases was applied and the patient was greatly improved.

Conclusion

This is the first well-documented case of sarcoidosis and psoriasis in the same patient, reported on the basis of safe and widely-used techniques that were not available until fairly recently. These disorders might share common pathogenic mechanisms that could explain their co-existence in the patient.
Coping with methodological dilemmas; about establishing the effectiveness of interventions in routine medical practice
Authors: Jansen Yvonne JFM , Bal Roland , Bruijnzeels Marc , Foets Marleen , Frenken Rianne , de Bont Antoinette
Published: December 2006

Background

The aim of this paper is to show how researchers balance between scientific rigour and localisation in conducting pragmatic trial research. Our case is the Quattro Study, a pragmatic trial on the effectiveness of multidisciplinary patient care teams used in primary health care centres in deprived neighbourhoods of two major cities in the Netherlands for intensified secondary prevention of cardiovascular diseases.

Methods

For this study an ethnographic design was used. We observed and interviewed the researchers and the practice nurses. All gathered research documents, transcribed observations and interviews were analysed thematically.

Results

Conducting a pragmatic trial is a continuous balancing act between meeting methodological demands and implementing a complex intervention in routine primary health care. As an effect, the research design had to be adjusted pragmatically several times and the intervention that was meant to be tailor-made became a rather stringent procedure.

Conclusion

A pragmatic trial research is a dynamic process that, in order to be able to assess the validity and reliability of any effects of interventions must also have a continuous process of methodological and practical reflection. Ethnographic analysis, as we show, is therefore of complementary value.
In situ analysis of FOXP3+ regulatory T cells in human colorectal cancer
Authors: Loddenkemper Christoph , Schernus Martin , Noutsias Michel , Stein Harald , Thiel Eckhard , Nagorsen Dirk
Published: December 2006

The immune system spontaneously responds to tumor-associated antigens in peripheral blood of colorectal cancer (CRC) patients. Regulatory T cells (Treg) are suspected of influencing the interaction between the tumor and immune system and thus the course of malignant diseases. However, the function of Tregs in the development of T cell responses and on the clinical course of CRC is not clear. We analyzed Treg infiltration (FOXP3 staining)in situin 40 CRC patients and investigated whether there is a correlation to disease stage, systemic T cell response, and survival. Treg infiltration was significantly higher in CRC than in healthy colon. Stromal Treg infiltration was significantly higher than epithelial infiltration in CRC. Furthermore, Treg infiltration in the tumor was significantly higher in limited disease than in metastatic CRC. The average Treg infiltration rate in the tumor was non-significantly higher in patients without systemic TAA-specific T cell response. Survival did not differ between patients with high Treg infiltration and those with low Treg infiltration. In conclusion, a direct link between Treg infiltration in the tumor and the development of a systemic T cell response in CRC cannot be proven. However, local Treg infiltration was significantly higher in limited disease, in which a systemic TAA-directed T cell responses is less frequently observed.
Effect of extracorporeal liver support by MARS and Prometheus on serum cytokines in acute-on-chronic liver failure
Authors: Stadlbauer Vanessa , Krisper Peter , Aigner Reingard , Haditsch Bernd , Jung Aleksandra , Lackner Carolin , Stauber Rudolf E
Published: December 2006

Introduction

Cytokines are believed to play an important role in acute-on-chronic liver failure (ACLF). Extracorporeal liver support systems may exert beneficial effects in ACLF via removal of cytokines. At present, two systems are commercially available, the Molecular Adsorbent Recirculating System (MARS™) and Fractionated Plasma Separation, Adsorption and Dialysis (Prometheus™). The aim of this study was to compare the effects of MARS and Prometheus treatments on serum cytokine levels and their clearances.

Methods

Eight patients with ACLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Thirty-four treatments (17 MARS, 17 Prometheus) were available for analysis. Serum cytokines were measured before and after each treatment, and cytokine clearance was calculated from paired arterial and venous samples and effective plasma flow one hour after the start of treatment.

Results

Baseline serum levels of interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-α), and soluble TNF-α receptor 1 were significantly elevated in patients with ACLF. Measurable plasma clearances were detected for all cytokines tested, but no significant changes in serum levels of any cytokine were found after treatments with MARS or Prometheus. In MARS treatments, IL-10 was cleared from plasma more efficiently than IL-6. Clearance of IL-10 was higher in Prometheus than in MARS treatments.

Conclusion

Cytokines are cleared from plasma by both MARS and Prometheus, but neither system is able to change serum cytokine levels. This discrepancy is probably due to a high rate of cytokine production in patients with ACLF.
An environmental signature for 323 microbial genomes based on codon adaptation indices
Authors: Willenbrock Hanni , Friis Carsten , Juncker Agnieszka S , Ussery David W
Published: December 2006

Background

Codon adaptation indices (CAIs) represent an evolutionary strategy to modulate gene expression and have widely been used to predict potentially highly expressed genes within microbial genomes. Here, we evaluate and compare two very different methods for estimating CAI values, one corresponding to translational codon usage bias and the second obtained mathematically by searching for the most dominant codon bias.

Results

The level of correlation between these two CAI methods is a simple and intuitive measure of the degree of translational bias in an organism, and from this we confirm that fast replicating bacteria are more likely to have a dominant translational codon usage bias than are slow replicating bacteria, and that this translational codon usage bias may be used for prediction of highly expressed genes. By analyzing more than 300 bacterial genomes, as well as five fungal genomes, we show that codon usage preference provides an environmental signature by which it is possible to group bacteria according to their lifestyle, for instance soil bacteria and soil symbionts, spore formers, enteric bacteria, aquatic bacteria, and intercellular and extracellular pathogens.

Conclusion

The results and the approach described here may be used to acquire new knowledge regarding species lifestyle and to elucidate relationships between organisms that are far apart evolutionarily.
Every Teacher a Literacy Teacher? An Analysis of the Literacy-related Messages in Secondary Methods Textbooks
Authors: Draper Roni Jo
Published: December 2006

Every teacher a reading teacher has been the call of educators who have made their life work the promotion of reading and writing for middle and high school students (Gray, 1925; Herber, 1970; Ruddell, 1997; Vacca & Vacca, 2002). State departments of education in many states in the United States require secondary content-area teachers to complete course work in content-area reading and writing in order to obtain a teaching license (Romine, McKenna, & Robinson, 1996), seemingly to support this notion that every content-area teacher should also be a teacher of reading and writing. Although these requirements may be changing to accommodate other state requirements (Stewart & O'Brien, 2001), course work in content-area literacy remains common. Instructors with expertise in adolescent and content-area literacy have provided preservice courses to inform secondary teachers of methods to infuse literacy instruction with content instruction in ways that strengthen students' content-area learning and promote general literacy development. However, despite the slogans, the legislation, and the coursework, limited instruction in literacy occurs in secondary content-area classrooms (Eldridge & Muller, 1986, in Alvermann & Moore, 1991; Ratekin, Simpson, Alvermann, & Dishner, 1985).
At Play on the Borders of the Diegetic: Story Boundaries and Narrative Interpretation
Authors: Mackey Margaret
Published: December 2006

Working with young readers, aged 10 to 14, as they responded to narrative texts in a variety of media (Mackey, 2002), I observed a recurring phenomenon: In a variety of ways they repeatedly stepped in and out of the fictional universe of their different stories. Some examples will perhaps give the flavor of this experience:

Two 14-year-old girls playing Starship Titanic alternate between lively engagement in the narrative world of the story and stepping outside the fiction to console themselves, “Oh well, if we die, we can just start again.” A 10-year-old girl speaks of alternating between the novel and the computer game of My Teacher is an Alien, using the novel as a source of game-playing repertoire. Two 10-year-old boys look at the DVD of the film Contact, learning how the special effects of an explosion scene were composed, and commenting on how their new awareness of scene construction would affect how they view the film in the future.

As I recorded and analyzed numerous examples of such behaviors, I was struck by a common element of interpretive activity on the boundaries of the fictional universe. Sensitized to the topic, I began to notice, and then to collect, examples of contemporary texts that foster various forms of such border crossing, in and out of the diegesis, the framework of events as narrated in the text. This article explores how an awareness of this aspect of contemporary texts may enhance our understanding of interpretive processes and expand what happens in literature classes.
Neuronal polarity is regulated by a direct interaction between a scaffolding protein, Neurabin, and a presynaptic SAD-1 kinase inCaenorhabditis elegans
Authors: Hung Wesley , Hwang Christine , Po Michelle D. , Zhen Mei
Published: December 2006

The establishment of axon-dendrite identity in developing neurites is essential for the development of a functional nervous system. The SAD serine-threonine kinases have been implicated in regulating neuronal polarization and synapse formation. Here, we show that the C. elegansSAD-1 kinase regulates axonal identity and synapse formation through distinct mechanisms. We identified a scaffolding protein, Neurabin (NAB-1), as a physiological binding partner of SAD-1. Both sad-1 and nab-1loss-of-function mutants display polarity defects in which synaptic vesicles accumulate in both axons and dendrites. We show that sad-1 and nab-1 function in the same genetic pathway to restrict axonal fate. Unlike sad-1, nab-1 mutants display normal morphology of vesicle clusters. Strikingly, although the physical interaction of NAB-1 with SAD-1 is necessary for polarity, it is dispensable for synapse morphology. We propose that Neurabin functions as a scaffold to facilitate SAD-1-mediated phosphorylation for substrates specific for restricting axonal fate during neuronal polarization.