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Quartz (trigonal, low-temperature α-quartz) is the most important polymorph of the silica (SiO2) group and one of the purest minerals in the Earth crust. The mineralogy and mineral chemistry of quartz are determined mainly by its defect structure. Certain point defects, dislocations and micro-inclusions can be incorporated into quartz during crystallisation under various thermodynamic conditions and by secondary processes such as alteration, irradiation, diagenesis or metamorphism. The resulting real structure is a fingerprint of the specific physicochemical environment of quartz formation and also determines the quality and applications of SiO2raw materials. Point defects in quartz can be related to imperfections associated with silicon or oxygen vacancies (intrinsic defects), to different types of displaced atoms, and/or to the incorporation of foreign ions in lattice sites and interstitial positions (extrinsic defects). Due to mismatch in charges and ionic radii only a limited number of ions can substitute for Si4+in the crystal lattice or can be incorporated in interstitial positions. Therefore, most impurity elements in quartz are present at concentrations below 1 ppm. The structural incorporation in a regular Si4+lattice site has been proven for Al3+, Ga3+, Fe3+, B3+, Ge4+, Ti4+, P5+and H+, of which Al3+is by far the most common and typically the most abundant. Unambiguous detection and characterisation of defect structures in quartz are a technical challenge and can only be successfully realised by a combination of advanced analytical methods such as electron paramagnetic resonance (EPR) spectroscopy, cathodoluminescence (CL) microscopy and spectroscopy as well as spatially resolved trace-element analysis such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and secondary-ion mass spectrometry (SIMS). The present paper presents a review of the state-of-the-art knowledge concerning the mineralogy and mineral-chemistry of quartz and illustrates important geological implications of the properties of quartz.

The statistical anionic copolymerisation of the biobased monomer β-myrcene with styrene in cyclohexane was investigated via in situ near-infrared (NIR) spectroscopy, focusing on the influence of the modifiers (i.e., Lewis bases) tetrahydrofuran (THF) and 2,2-di(2-tetrahydrofuryl)propane (DTHFP) on the reactivity ratios. With increasing [modifier]/[Li] ratio, the reactivity ratios in the system myrcene/styrene are adjustable from rS ≪ rMyrvia rS ≈ rMyr to rS ≫ rMyr. The bidentate modifier DTHFP affects the reactivity ratios much more than THF: minute amounts only (0.35 equivalent relative to Li) are required to randomize the copolymer, and one equivalent to invert the reactivity ratios. Using these reactivity ratios, copolymer composition profiles are obtained, which upon increasing the modifier concentration vary from tapered, block-like copolymers to random to inversely tapered copolymers. 1H-NMR spectroscopy was used to determine the microstructure of the myrcene units in the copolymers. With increasing [modifier]/[Li] ratio, the content of 1,4-units decreases and the content of 3,4- and 1,2-units increases. DTHFP as a modifier minimizes the content of 1,2-units. The glass transition temperatures also depend on the [modifier]/[Li] ratio, but less strongly than in the copolymer poly(styrene-co-isoprene). Although all copolymers have the same composition (33%mol myrcene, corresponding to 39.6%weight and 45%vol), very similar molecular weights (about 90 kg mol−1) and low dispersities (1.06 to 1.10), different morphologies could be obtained. Lamellar, cylindrical and gyroid structures were identified by TEM and SAXS measurements. The mechanical properties vary in a wide range from hard and brittle to soft and flexible. The gyroid structure showed the highest Young's modulus and no viscoelastic deformation.

Based on the highly disparate reactivities of isoprene (I

The reactivity of the biobased monomer β-farnesene in the statistical anionic copolymerization with styrene and the effect of the bottlebrush-like polyfarnesene structure on the phase separation be...

The recently discovered Serra Branca amazonite pegmatite in the state of Paraíba, Brazil, is an evolved niobium-yttrium-fluorine (NYF) granitic pegmatite, which belongs to the Vieirópolis pegmatite field, the first NYF pegmatite field described from the Borborema Province. The pegmatite is an unusually large resource (>300,000 tons) of intensely colored amazonite megacrysts up to 2 m in size, exploited in an open pit since ca. 2010 as an ornamental stone and gemological material. This study provides the first mineralogical and geochemical characterization of the Serra Branca amazonite pegmatite and its mineralogy, which are further compared with the mineralogy and composition of other NYF pegmatites. The Serra Branca pegmatite forms an approximately 800 m-long and up to 3 m-thick flat-dipping sheet that consists of two distinct structural-mineralogical zones with complex relationships: (1) the massive, megacrystic amazonite zone forming commonly in the upper part of the dike and (2) the fine-grained albite zone commonly occurring at the bottom of the dike. The amazonite zone, which comprises ca. 75 vol.% of the pegmatite body, is composed of amazonite and quartz, the major constituents, with accessory biotite, helvine, galena, ilmenite, hematite, columbite-(Mn), phenakite, titanite, magnetite, and rutile. The albite zone consists of saccharoidal albite and quartz and accessory spessartine, ilmenite, zircon, columbite-(Mn), pyrochlore, and fluorite. A younger minor intrusive pegmatitic unit composed of megacrystic euhedral amazonite and quartz and platy albite (cleavelandite) postdates the formation of the amazonite and albite zones. Geochemical analysis of the bulk pegmatite, amazonite zone, and albite zone shows that the bulk pegmatite and the amazonite zone have similar compositions, with high trace-element contents of Ba, Be, Rb, Sr, and Pb, whereas the albite zone is enriched in Zn, Nb, Zr, Ga, and Hf. The amazonite and albite zones display some similarities in terms of major elements, the presence of HFSE minerals, and the distribution of incompatible and REE, which indicates that the two zones originated from the same melt. The amazonite crystals are enriched in Rb, Pb, Sr, Cs, Ba, Tl, Fe, and Ga, characterizing the Serra Branca pegmatite as an evolved NYF pegmatite. This conclusion is confirmed by the low K/Rb ratio of biotite of ∼5.7. Higher Li and Ga and lower Sr and Ba in the amazonite of the minor unit suggests that this melt was even more highly fractionated than the melt of the first emplacement stage.

The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disor...

[EN]Quartz from 254 pegmatites representing eight pegmatite fields and provinces worldwide was investigated by laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to determine concentrations of trace elements Al, Ti, Li, Ge, B, Be, Rb, Na, K, Ca, P, Ga, Sb, Zn and U. A total of 271 new analyses combined with 535 published LA-ICP-MS quartz chemistry data were evaluated with binary and ternary trace element discrimination plots and principal component analysis (PCA). The classifications applied for discrimination of pegmatite types include the widely applied NYF(Nb-Y-F) - LCT(Li-Cs-Ta) classification and the new RMG (pegmatites derived from residual melts of granite magmatism) - DPA (pegmatites as direct products of anatexis) grouping. Pegmatites of both classifications can be well distinguished via Al-Ti, Al-Li and Al/Ti-Ge/Ti binary trace element plots and the Ti - A1/10 - 10*Ge ternary diagram. PCA applied to Al, Li, Ti, Be, B, Ge and Rb contents in quartz allowed to further distinguish between anatectic DPA-1 (Li-enriched DPA) and granite-pluton-derived RMG-1 (Lienriched RMG) pegmatites. Some pegmatite fields and provinces (Hagendorf-Pleystein, Oxford County) are distinguishable by region-specific Li, Ge and Al contents. The results imply that the chemistry of pegmatite quartz is mainly controlled by the origin (source rock chemistry) of pegmatite melts and, to a much lesser extent, by the geodynamic setting of the pegmatite fields and provinces. Chemically primitive NYF and DPA-2 type pegmatites contain quartz with the lowest total trace-element contents and lowest internal-pegmatite trace-element variation, making it potentially suitable for high-tech application. Pegmatite quartz containing >30 mu gg(-1) Li and >100 mu gg(-1) Al is strongly indicative of economic spodumene/montebrasite mineralization and, thus, serves as a strong Li-mineralization pathfinder mineral. Quartz with >5 mu gg(-1) B may be a potential indicator for gem-quality tourmaline mineralization. The authors are very thankful for the constructive reviews by Roland Stalder and an anonymous reviewer and for the editorial handling of this paper by the editor Karen H. Johannesson. This study is funded by European Commission's Horizon 2020 innovation programme under grant agreement No 869274, project GREENPEG New Exploration Tools for European Pegmatite Green-Tech Resources."The grant ID is consequently EU H2020 GA869274.

The living anionic copolymerization of isoprene (I) and styrene (S) can afford a variety of different polymer microstructures that strongly depend on experimental parameters such as solvent, counte...

The Sveconorwegian orogen (1.1–0.9 Ga), covering southern Norway, is known for its large pegmatite province containing more than 5000 pegmatite bodies, divided into several pegmatite fields (Fig. 1). Most of these pegmatites have a chemical niobium-yttrium-fluorine (NYF) signature. The orogen is intruded by several, large post-orogenic A-type granites that classically were thought to be the source of the pegmatite melts. This was first challenged by Müller et al. (2015) stating that some of the pegmatites were formed by anatectic melting of their amphibolitic host-rock. In this study we use U-Pb age dating of columbite group minerals and ixiolite from seven Sveconorwegian pegmatites to shed light on their formation and temporal relationship to the spatially related granites. Furthermore, the data set is utilized for providing information on whether the pegmatite formation is related to known Sveconorwegian orogenic stages or represents their own regional melting event.

In a combined synthetic, kinetic and theoretical study, the living anionic copolymerization of styrene and its ring-methylated derivatives ortho-, meta-, and para-methylstyrene (MS) was examined by real-time 1H NMR spectroscopy in the nonpolar solvents toluene-d8 and cyclohexane-d12 as well as by density functional theory calculations. Based on the NMR kinetics data, reactivity ratios for each comonomer pair were determined by the Kelen–Tudős method and numerical integration of the copolymerization equation (Contour software). The reaction pathway was modeled and followed by density functional theory (DFT) calculations to validate and predict the experimentally derived reactivity ratios. Unexpectedly, two of the three styrene derivatives showed completely different reactivities in copolymerization, governed by the position of the methyl group. While para-MS is considerably less reactive than styrene, resulting in gradient copolymers (rS = 2.62; rpMS = 0.37), ortho-MS showed the opposite behavior and is mo...

The synthesis of tapered multiblock copolymers by statistical living anionic copolymerization of a mixture of isoprene (I) and 4-methylstyrene (4MS) in cyclohexane is based on vastly different reac...

To explore the potential of myrcene (Myr) as a bio-based monoterpene comonomer for styrenic copolymers and to establish its general applicability for the carbanionic copolymerisation, several statistical copolymerisations of myrcene and common monomers like isoprene (I), styrene (S) and 4-methylstyrene (4MS) were carried out in cyclohexane and monitored by in situ1H NMR spectroscopy. Real-time NMR kinetic studies permitted the determination of the reactivity ratios and the composition profile for each monomer combination. While the copolymerisation of Myr/I yielded a gradient copolymer and reactivity ratios of moderate disparity (rMyr = 4.4; rI = 0.23), the statistical copolymerisation of Myr/S and Myr/4MS afforded block-like, tapered copolymers due to highly diverging reactivity ratios (rMyr = 36; rS = 0.028 and rMyr = 140; r4MS = 0.0074). Furthermore, a terpolymerisation of Myr/I/4MS was studied by real-time NMR kinetics, revealing an alteration of the composition profile of 4MS towards a more block-like structure. Based on the kinetic studies, a series of Myr/I/4MS terpolymers and Myr/S copolymers was prepared by statistical living anionic copolymerisation. All copolymers showed narrow molecular weight distributions (SEC) and two glass transition temperatures (Tg,1 = −51 to −62 °C; Tg,2 = 93 to 107 °C), suggesting phase segregation. TEM and SAXS measurements revealed highly ordered lamellar morphologies for all copolymers with long range correlation and confirmed the block-like structure and behaviour of Myr/S and Myr/4MS copolymers prepared by statistical carbanionic copolymerisation.

The living anionic copolymerization of isoprene and styrene in cyclohexane affords tapered block copolymers due to the highly disparate reactivity ratios of rI = 12.8 and rS = 0.051. Repeated addit...

This study represents the precursor and complementary study for the new classification of granitic pegmatites by Wise et al. (this issue) and provides a detailed analysis of existing classifications of granitic pegmatites in terms of applied classification criteria and applicability. The analyses revealed that a new classification scheme for granitic pegmatites is required. In the second part measurable, inferred, and presumed classification criteria applicable for the classification of pegmatites are listed and discussed, including how they should be utilized in future classification schemes. This study records the process of how the new classification scheme for pegmatites was developed.

Trace elements of quartz document the physical-chemical evolutions of quartz growth, which has been a great and most applied tool in the study of geological settings in quartz-forming environments. A classic method is using graphic diagram plots visualizing the quartz trace element discriminations and trends, examples including the Al-Ti diagram (Rusk, 2012, https://doi.org/10.1007/978-3-642-22161-3_14) and the Ti-Al-Ge diagram (Schrön et al., 1988, https://www.researchgate.net/publication/236149159_Geochemische_Untersuchungen_an_Pegmatitquarzen). However, those diagrams are limited to two dimensions and cannot show the information in a higher dimension. In the study, we thus used a machine learning-based approach to evaluate quartz trace elements, and visualized them for the first time in the high-dimensional diagrams. We revisited 1,626 quartz samples from nine geological environments from previous studies, and applied a support vector machine to characterize values of the contained trace elements, including Al, Ti, Li, Ge, and Sr. We demonstrate that support vector machines can identify the crystallization environment of quartz with a significantly higher accuracy than the traditional plotting methods. Our work can massively improve the confidence on distinguishing quartz origin from different geological environments with a high efficiency. The method may also be applicable for other minerals, and we anticipate our research is a starting point for investigating mineral trace elements with machine learning techniques. Our quartz classifier can be accessed via https://quartz-classifier.herokuapp.com.

Janus particles, named after the double-faced Roman god, are compartmentalized colloids with two sides of different chemistry or polarity. This makes them a unique class of materials among micron- or nanosized particles. Due to this special non-centrosymmetric feature in the particle architecture, the synthesis of Janus particles remained challenging for a long time. However, major progress concerning their preparation in useful amounts has been achieved in recent years. The interest in these particles arises from their fascinating hierarchical superstructures in solution and from the fact that demanding problems in materials science, biomedicine and in the field of highly specific sensors can be tackled with this class of particles with advanced properties. This article highlights preparation pathways, self-assembly processes and various pursued applications.

Environmental sciences Europe : ESEU 32, 85 (2020). doi:10.1186/s12302-020-00358-x, Published by Springer, Berlin ; Heidelberg

We show that confocal microscopy arrangement in conjunction with metallic mirrors or beam splitters enhance the cross-polarization extinction by several orders of magnitude, with a view to facilitating the detection of the resonant fluorescence emission.

High-MgO (>12 wt%) magmas represent some of the most primary and high temperature melts from mantle plumes. The compositional diversity of high-MgO magmas gained by fractional melting within inhomogeneous mantle sources, is often overprinted by wall rock assimilation, magma mixing and fractional crystallisation within magma chambers at various depths within the crust. The deepest intrusions, at the base of the crust, are the first stop for magmas as they leave the mantle and such localities offer vital insights into the crustal processes that modify high-MgO melts. The Seiland Igneous Province (SIP) represents a rare exposure of a deep crustal magma conduit system that transported large volumes of mantle-derived melts through the lower continental crust. In this work, trace element compositions of clinopyroxenes in dunite, wehrlite and olivine clinopyroxenite samples from the Reinfjord intrusion were measured using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The melts calculated to be in equilibrium with the clinopyroxenes represent derivatives of mantle-derived magmas and have steep rare earth element (REE) profiles with La/YbPM of 8.4–14., Sm/YbPM of 3.5–4.8, and negative anomalies in Nd, Zr and Hf. Assimilation, recharge and fractional crystallisation modelling shows that the ultramafic cumulates in the Reinfjord intrusion formed through concurrent fractional crystallisation and repetitive recharge (and mixing) of new primitive magmas from the mantle with very limited input from crustal sources. The recharge and mixing model is strongly supported by field and petrographic data. Two end-member ultramafic magmas are identified; the first end-member melt composition (MELTCPX0) is similar to the melt compositions that are in equilibrium with the most trace element depleted clinopyroxenes from Reinfjord. The second end-member melt composition (MELTPIC0) is similar to a number of picrite dykes found throughout the SIP, which have less steep LREE/HREE and lack strong negative anomalies in Zr and Hf. The REEBOX PRO melting model (Brown and Lesher, 2016) was used to forward model adiabatic decompression melting of lithologically homogeneous and heterogeneous sources containing anhydrous/hydrous peridotite ± pyroxenite. It was found that MELTPIC0 formed by melting of a peridotite source with up to 10% pyroxenite component and mantle potential temperatures of up to 1450 °C. MELTCPX0, however, formed by melting of a carbonate- metasomatised peridotite with potential temperatures of up to 1630 °C. These results indicate a compositionally and thermally inhomogeneous mantle plume beneath the SIP. /© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Block copolymer (BCP) self-assembly is one of the most versatile concepts for the bottom-up design of functional nanostructures in materials science, nanomedicine and nanotechnology. While BCPs have been extensively studied regarding their microphase separation in bulk and the self-assembly in solution, only recently BCPs were investigated for their ability to form internally ordered microparticles. In this review, we discuss two emerging concepts: (i) the microphase separation of BCPs in the spherical confinement of evaporating emulsion droplets and (ii) the self-assembly of highly asymmetric BCPs under concentrated conditions. While the first concept yields solid and compact multicompartment microparticles suited for the synthesis of shape-anisotropic nanoparticles, photonic colloids, and actuators, the latter produces highly regular porous microparticles with exceptional interfacial area (BCP cubosomes and hexosomes). Despite distinct differences in the origin of both fields, commonalities in shape and morphology suggest an underlying formation mechanism that may link both research directions.

Magmatic and hydrothermal quartz populations related to the Late-Variscan Zinnwald/Cínovec Sn-W-Li greisen-type deposit in the Eastern Erzgebirge/Krušné Hory (German/Czech Republic) were studied in terms of trace element contents and growth structures visualized by cathodoluminescence. The sample suite represents different populations of hydrothermal greisen quartz and magmatic quartz of the granitic host collected at a 600-m long, lateral section crosscutting the northern part of the deposit at the 750-m level. The studied quartz populations are characterized by generally low concentrations and low variation of Al and Ti indicating relatively constant crystallization conditions (temperature, pressure and fluid chemistry) during ore precipitation. Magmatic and hydrothermal quartz are distinguished by their Al, Ti, Li and Ge concentrations and ratios. Magmatic quartz has commonly higher Al (>100 ppm) and Ti (>3 ppm) compared to hydrothermal quartz. The Ge/Al ratio in quartz increases systematically from high to low formation temperatures (664 to ~400 °C = temperature range including published data and our estimates) whereas Ti decreases. The Zinnwald albite granite (mineralization host), an albite-rich alkali granite, and massive quartz-zinnwaldite greisen contain both magmatic and hydrothermal quartz populations which are distinguishable by their Ge/Al weight ratio: magmatic quartz has a Ge/Al ratio of 0.008. Hydrothermal vein quartz related to the Sn-W mineralization (Flöze = flat veins and Morgengänge = steep veins) does not show systematic trace element variations along the sampling profile indicating that no significant chemical gradients (in lateral direction) in the ore forming fluid existed. The uptake of Li in the quartz lattice is limited by the incorporated Al although the Zinnwald/Cínovec magmatic-hydrothermal system was strongly enriched in Li. The calculated crystallization temperatures of quartz of the Sn-W mineralization applying the TitaniQ thermobarometer reveal crystallization temperatures ranging from 575 ± 48 °C (albite granite), 612 ± 12 °C (stockscheider), 610 ± 23 (massive greisen), 536 ± 77 °C (flat veins), to 516 ± 58 °C (steep veins) confirming in general early estimations based on fluid and melt inclusion studies. In economic terms, the hydrothermal quartz (flat and steep veins) with an average total trace element content of 128 ± 56 ppm has intermediate chemical quality and can serve as a by-product if colour sorting and other processing steps are applied. Rock-forming quartz of albite granite and massive greisen with an average total trace element content of 233 ± 127 ppm has medium quality and the disadvantage that quartz contains a high amount of contaminating mineral inclusion, which will be challenging to remove by processing.

Based on the highly disparate reactivities of isoprene (I, rI = 25.4) and 4-methylstyrene (4MS, r4MS = 0.007) in the anionic copolymerization in nonpolar media, a general strategy for the rapid and scalable synthesis of tapered multiblock copolymers with an extremely steep gradient has been developed. A repetitive addition strategy of a mixture of isoprene and 4MS leads to a tapered diblock in each case, giving access to linear alternating multiblock copolymers of the (AB)n type with up to 10 blocks. All multiblock copolymers showed narrow molecular weight distributions (dispersity Đ = 1.04–1.12). High molecular weights in the range of 80 to 400 kg mol–1 were achieved. Due to the incompatibility of PI and P4MS segments, the multiblock copolymers exhibit nanophase separation, manifested by separate glass transitions for both constituents. Stress–strain measurements revealed extraordinary toughness and elongations up to 1150% strain at break, even at a 50/50 molar ratio I/4MS (i.e., 37 wt% isoprene). Our sy...

In previous studies, we have found that un-complexed free cationic polymers greatly promote gene transfection efficiency of pDNA complexes. Dividing the gene transfection system into two parts, bound chains and free chains, we exploited mixing different biomaterials as the second component of our designed system to improve gene transfection outcome. In this study, we investigated the effectiveness of star-shaped poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) with different arm numbers as free chains (i.e., co-transfection agent) while using natural salmon protamine as bound chains. We explored the gene transfer ability of the system in both serum free and complete cell culture medium. Our results reveal that the star-shaped PDMAEMAs enhance gene transfection efficiency of protamine/pDNA complexes, in the same range and even better than the gold standard polyethyleneimine (PEI, branched type with 25 kg/mol molar mass) in serum-free and serum containing medium conditions, respectively. From 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Lactate Dehydrogenase (LDH) release data, it was found that the PDMAEMA stars have tolerable cytotoxicity but with significant membrane disruption level, especially when increasing the arm number. Flow cytometry experiments showed that PDMAEMA stars clearly improve the uptake rate as well as the number of protamine/pDNA complexes taken up by the target cells. Using Taqman Real-time Polymerase Chain Reaction (PCR), further exploration of the effect of PDMAEMAs during different gene transfection stages reflects that these un-bound star-shaped polymers mainly act upon the cellular internalization step. Our results indicate that the star-shaped PDMAEMAs are promising vectors for gene delivery.

Block copolymers of polyisoprene and polystyrene are key materials for polymer nanostructures as well as for several commercially established thermoplastic elastomers. In a combined experimental and kinetic Monte Carlo simulation study, the direct (i.e., statistical) living anionic copolymerization of a mixture of isoprene (I) and 4-methylstyrene (4MS) in nonpolar media was investigated on a fundamental level. In situ 1H NMR spectroscopy enabled to directly monitor gradient formation during the copolymerization and to determine the nature of the gradient. In addition, a precise comparison with the established copolymerization of isoprene and styrene (I/S) was possible. Statistical copolymerization in both systems leads to tapered block copolymers due to an extremely slow crossover from isoprene to the styrenic monomer. For the system I/4MS the determination of the reactivity ratios shows highly disparate values with rI = 25.4 and r4MS = 0.007, resulting in a steep gradient of the comonomer composition. Th...

The genetic relationship between a granite pluton and adjacent complex of rare-metal pegmatite-aplite-banded sheets (Megiliggar Sheet Complex - MSC) has been studied at the border of the Tregonning topaz granite at Megiliggar Rocks, Cornwall, SW England. Similarities in whole-rock chemical and mineralogical compositions, together with a gradual change in textures away from the granite margin, provide strong evidence for a genetic link between the Tregonning Granite and MSC. The sheets are likely to represent apophyses of residual melt which escaped from the largely crystallized roof of the granite pluton. The escaping melt was peraluminous, had a composition near the F, B, Li slightly enriched granite minimum, and, in comparison with other Cornish granites, was enriched in F, Li, Rb, Cs, Sn, W, Nb, Ta, and U, and depleted in Fe, Mg, Ca, Sr, Th, Zr, and REE. With increasing distance from the Tregonning Granite, the silicate melt crystallized as homogeneous leucogranite sheets and banded complex sheets (i.e. combinations of bands with granitic, aplitic and pegmatitic textures), then layered aplite-pegmatites; this sequence becoming progressively more depleted in the fluxing and volatile elements F, Li, Rb, and Cs, but showing no change in Zr/Hf ratios. The fixed Zr/Hf ratio is interpreted as indicating a direct genetic link (parental melt) between all rock types, however the melt progressively lost fluxing and volatile elements with distance from the granite pluton, probably due to wall-rock reaction or fluid exsolution and migration via fractures. Differentiation of the primary melt into Na-Li-F-rich and separate K-B-rich domains was the dominant chemical process responsible for the textural and mineral diversity of the MSC. On a large (cliff-section) scale, the proximal Na-Li-F-rich leucogranite passes through complex sheets into K-B-rich aplite-pegmatites, whilst at a smaller (

The reforming of diesel and diesel-like fuels plays a central role in the development of fuel cell systems for on-board power supplies. The vaporization of the fuel via a spray formation and the subsequent mixture with water vapor and air determine the quality of the reforming process, as is shown in this paper. By using a high quality nozzle residual hydrocarbons were below 25 ppmV during the reforming of standard diesel. Through the use of a fuel injector in pulsed operation, the load range was able to be increased from 1:1.67 to 1:6. Spray pattern analyses were conducted using a high-speed camera. The formation of the spray pattern lasted 1.5–2 ms. The testing of a fast-closing magnetic valve manufactured by GSR Ventiltechnik was carried out on the autothermal reformer (ATR) type AH2. It exist not any direct influence of the pulsed operation on hydrogen production.

Zusammenfassung Vor sechzig Jahren entdeckte Michael Szwarc die lebende anionische Polymerisation. Trotz ihrer hohen synthetischen Anforderungen ist sie bis heute die praziseste Methode zur Herstellung von wohldefinierten Polymeren und inspirierte zahlreiche neue Polymerisationsmethoden. Masgeschneiderte Blockcopolymere finden sich in den verschiedensten Anwendungen von High-End-Verpackungsmaterialien uber die Elektronik bis hin zu Nanomedizin.

By influencing both the interfacial adhesion and the morphology, compatibilizers determine the mechanical properties of polymer blends. Here, we study the mechanical properties, in particular the fatigue crack propagation (FCP) of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene- co -acrylonitrile) (PPE/SAN), compatibilized with Janus nanoparticles (JPs) and linear polystyrene- block -polybutadiene- block -poly(methyl methacrylate) (SBM) triblock terpolymers. Synergistic effects of a mixture of both compatibilizers improve the FCP behavior and reveal the important role of interface stiffness and flexibility on the mechanical properties of polymer blends. The triblock terpolymer and JPs allow at the same time an elastic and stiff linkage at the blend interface and induce multiple deformation mechanisms such as crack bridging and matrix fibrillation that can dissipate energy and contribute to an improved FCP behavior. The presented concept allows tailoring macro-mechanical properties of immiscible polymer blends by adjusting blend morphology and interfacial properties.

The stabilization of water/air, water/oil and water/solid interfaces by Janus particles with polystyrene (PS) and poly(methacrylic acid) (PMAA) hemispheres was systematically investigated. The stabilization of these interfaces is of relevance for the formulation of foams, emulsions and dispersions. The Janus particles were prepared from micellar solutions of polystyrene-b-polyisoprene-b-poly(tert-butyl methacrylate) (PS-PI-PtBMA) triblock terpolymers by selective cross-linking of the polyisoprene domain on a multi-gram scale, followed by hydrolysis of the PtBMA block. For the investigation of water/oil-emulsions a series of hydrophobic oils (paraffin oil, xylene, peanut oil, isopropyl myristate) with increasing polarity was selected. We found that the Janus particles do not stabilize the air/water interface and efficiently suppress foaming. The Janus particles showed a pronounced selectivity in their efficiency to stabilize w/o-emulsions. Isopropyl myristate water/oil emulsions could be stabilized up to several months with only 0.2 wt.-% of Janus particles. In general, interfaces with air and very hydrophobic oils and pigments were not stabilized, indicating that a certain polarity and interfacial mobility is necessary for an efficient stabilization by Janus particles. The Janus particles can be used as sole stabilizers in the soap-free emulsion polymerization of styrene/n-butyl acrylate or methyl methacrylate/n-butyl acrylate under commercially relevant semi-batch reaction conditions. Polymer coatings prepared from Janus particle-stabilized acrylate and styrene/acrylate dispersions showed a significantly reduced surface hydrophobicity as compared to surfactant-stabilized dispersions.

Zircon from 14 representative granite samples of the late-Variscan Cornubian Batholith in SW England was analysed for W, P, As, Nb, Ta, Si, Ti, Zr, Hf, Th, U, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Al, Sc, Bi, Mn, Fe, Ca, Pb, Cu, S and F using electron probe microanalyses. Zircons from the biotite and tourmaline granites are poor in minor and trace elements, usually containing 1.0–1.5 wt.% HfO2

The Parana deposit, located at Southwestern Rio Grande do Norte state, in Brazil, is one of the few emerald deposits found at Borborema Province. The mineralization occurs in phlogopite schists and actinolite-phlogopite schists associated with pegmatites and albitites within the Portalegre Shear Zone. Unlike other well-known Brazilian emerald deposits, the mineralogy of Parana emeralds has remained poorly investigated for the last 40 years. In this study, we conducted mineralogical characterization of theses emeralds through gemological testing, mineral chemistry, absorption and reflectance spectroscopy, and thermal analysis. The Parana emeralds are bluish-green colored, characterized by high refractive index, several two-phase fluid inclusions and mica is the main mineral inclusion. Electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry analyses detected the presence of Fe2+ (0.43-1.94 wt.% FeO) and Cr3+ (0.04-0.14 wt.% Cr2O3) as the main chromophores replacing octahedral Al3+ in the crystal structure. In addition, substantial amounts of MgO (0.40-2.72 wt.%), Na2O (0.50-1.81 wt.%), and Cs2O (0.07-0.44 wt.%) were also identified. The main causes for its coloration were attributed to Cr3+ absorption features in visible spectral range, which were corroborated by absorption and reflectance spectra. The presence of types I and II H2O at channel-sites was recorded in Fourier-transform infrared spectra and demonstrated by dehydration processes observed in different thermal and thermogravimetric analyses.