The properties of semiconducting polymers are strongly influenced by their aggregation behavior, that is, their aggregate fraction and backbone planarity. However, tuning these properties, ...particularly the backbone planarity, is challenging. This work introduces a novel solution treatment to precisely control the aggregation of semiconducting polymers, namely current‐induced doping (CID). It utilizes spark discharges between two electrodes immersed in a polymer solution to create strong electrical currents resulting in temporary doping of the polymer. Rapid doping‐induced aggregation occurs upon every treatment step for the semiconducting model‐polymer poly(3‐hexylthiophene). Therefore, the aggregate fraction in solution can be precisely tuned up to a maximum value determined by the solubility of the doped state. A qualitative model for the dependences of the achievable aggregate fraction on the CID treatment strength and various solution parameters is presented. Moreover, the CID treatment can yield an extraordinarily high quality of backbone order and planarization, expressed in UV–vis absorption spectroscopy and differential scanning calorimetry measurements. Depending on the selected parameters, an arbitrarily lower backbone order can be chosen using the CID treatment, allowing for maximum control of aggregation. This method may become an elegant pathway to finely tune aggregation and solid‐state morphology for thin‐films of semiconducting polymers.
This work introduces a novel solution treatment utilizing spark discharges to enable a highly controlled aggregation of semiconducting polymers. The aggregate fraction and the quality of the polymer backbone order can be finely tuned over exceptionally broad ranges by choosing appropriate parameters for this current‐induced doping treatment.
Pyrochlore from the Kaiserstuhl volcanic complex (SW Germany) shows textural and compositional differences between various coarse-grained calcite-carbonatite bodies (Badberg, Degenmatt, Haselschacher ...Buck, Orberg) and extrusive carbonatites (Henkenberg, Kirchberg).
Oscillatory-zoned F-rich pyrochlore with up to 69 wt% Nb2O5 is common in all coarse-grained calcite-carbonatite bodies and probably formed during magmatic conditions. However, only in some of the samples from the Badberg, partly resorbed U- and Ta-enriched pyrochlore cores with up to 22 wt% UO2 and 9 wt% Ta2O5 have been identified, which are interpreted as being inherited from underlying nosean syenites. Pyrochlore data from a drill core penetrating the Badberg indicate increasing contents of REE, U, and Ta with depth, while Nb, F and Na contents decrease. This may reflect the combined effects of fractional crystallization and assimilation (AFC) or indicates a multi-stage emplacement of the carbonatitic magma. Patchy-zoned ceriopyrochlore and REE- and Th-enriched pyrochlore with up to 19 wt% total REE2O3 and 6.5 wt% ThO2 is largely restricted to samples from the Orberg and probably formed during hydrothermal conditions. This can be related to the relatively evolved character of the Orberg carbonatites, based on their relatively high whole-rock Nb/Ta and Zr/Hf mass ratios. This study demonstrates that the textural and compositional variation of pyrochlore in carbonatites is a powerful tool to distinguish magmatic, hydrothermal and weathering processes in carbonatitic systems.
Abstract
The mineralogy and mineral chemistry of the four major sövite bodies (Badberg, Degenmatt, Haselschacher Buck and Orberg), calcite foidolite/nosean syenite xenoliths (enclosed in the Badberg ...sövite only) and rare extrusive carbonatites of the Kaiserstuhl Volcanic Complex in Southern Germany provide evidence for contamination processes in the carbonatitic magma system of the Kaiserstuhl. Based on textures and composition, garnet and clinopyroxene in extrusive carbonatites represent xenocrysts entrained from the associated silicate rocks. In contrast, forsterite, monticellite and mica in sövites from Degenmatt, Haselschacher Buck and Orberg probably crystallized from the carbonatitic magma. Clinopyroxene and abundant mica crystallization in the Badberg sövite, however, was induced by the interaction between calcite foidolite xenoliths and the carbonatite melt. Apatite and micas in the various sövite bodies reveal clear compositional differences: apatite from Badberg is higher in REE, Si and Sr than apatite from the other sövite bodies. Mica from Badberg is biotite- and comparatively Fe2+-rich (Mg# = 72–88). Mica from the other sövites, however, is phlogopite (Mg# up to 97), as is typical of carbonatites in general. The typical enrichment of Ba due to the kinoshitalite substitution is observed in all sövites, although it is subordinate in the Badberg samples. Instead, Badberg biotites are strongly enriched in IVAl (eastonite substitution) which is less important in the other sövites. The compositional variations of apatite and mica within and between the different sövite bodies reflect the combined effects of fractional crystallization and carbonatite-wall rock interaction during emplacement. The latter process is especially important for the Badberg sövites, where metasomatic interaction released significant amounts of K, Fe, Ti, Al and Si from earlier crystallized nosean syenites. This resulted in a number of mineral reactions that transformed these rocks into calcite foidolites. Moreover, this triggered the crystallization of compositionally distinct mica and clinopyroxene crystals around the xenoliths and within the Badberg sövite itself. Thus, the presence and composition of clinopyroxene and mica in carbonatites may be useful indicators for contamination processes during their emplacement. Moreover, the local increase of silica activity during contamination enabled strong REE enrichment in apatite via a coupled substitution involving Si, which demonstrates the influence of contamination on REE mineralization in carbonatites.
Objectives The majority of nosocomial Staphylococcus aureus infections originate from the patients’ own flora, with nasal carriage of S. aureus before surgical procedures being a risk factor for ...subsequent infection. The objective of this review was to assess whether intranasal mupirocin treatment of nasal S. aureus carriers before surgery results in a reduction of the post-operative S. aureus infection rate. Methods CENTRAL, EMBASE and MEDLINE were searched for the keywords mupirocin, pseudomonic acid or bactroban, combined with nasal or intranasal. Only randomized controlled studies investigating surgical patients were included. Titles and abstracts were screened independently by two reviewers. S. aureus infection data in nasal carriers with and without mupirocin treatment were pooled in the meta-analysis. Results The literature search resulted in 211 hits, of which 4 articles met the inclusion criteria. Among the 686 mupirocin-treated surgical patients with S. aureus nasal carriage, there were 25 S. aureus infections (3.6%), compared with 46 (6.7%) in the controls (RR 0.55, 95% CI 0.34–0.89; P = 0.02). Conclusions Prophylactic intranasal mupirocin significantly reduced the rate of post-operative S. aureus infections among surgical patients who were S. aureus carriers.
Abstract Upper Cretaceous–Miocene alkaline SiO2-undersaturated volcanic rocks in the southern Central European Volcanic Province (CEVP) comprise two distinct rock series: (i) Upper Cretaceous–Eocene ...(~73–47 Ma) olivine nephelinites, basanitic nephelinites, and nepheline basanites have moderate to high MgO (8–16 wt. %), CaO, Ni, Co, Cr, Nb, and Ba, coupled with low F and SiO2 concentrations. These rocks contain abundant clinopyroxene and variable amounts of olivine macrocrysts as well as nepheline, K-dominated F-poor mica, and hydroxyapatite. Evolved and less common apatite-rich (phonolitic) haüynites/noseanites and haüyne nephelinites (~68–62 Ma) represent differentiated counterparts within this older group, showing higher alkali, Al2O3, P2O5, Nb, Zn, REE, and SO3 concentrations at low MgO (4–6 wt. %), CaO, Ni, Co, and Cr contents. (ii) Oligocene–Miocene (~27–9 Ma) olivine melilitites and melilite-bearing olivine nephelinites are characterized by even higher MgO (10–22 wt. %), CaO, Ni, Co, Cr, Nb, Ba, and high F contents at lower SiO2 concentrations, as reflected by the presence of abundant olivine macrocrysts, melilite, perovskite, Cr-rich spinel, F- and Ba-rich mica, and fluorapatite in addition to clinopyroxene and nepheline. Distinct mineral assemblages, crystallization trends, and various xenocrysts indicate different melt sources, a varying extent of enrichment, retention, and loss of volatiles (including timing of H2O and CO2 saturation), and limited wall rock interaction for the two rock groups. Partly resorbed, Fo-depleted olivine cores in the younger rocks and green-core pyroxenes in the older ones suggest early magma mixing. The nephelinitic–basanitic magmas derived from up to 6% partial melting of amphibole-bearing garnet/spinel lherzolite at or just above the lithosphere–asthenosphere boundary. This source was metasomatized involving hydrous melts or fluids. On the other hand, the melilite-bearing rocks probably originated in the upper asthenosphere by less than 3.5% partial melting of amphibole ± phlogopite-bearing garnet wehrlite, previously generated by subduction-related metasomatism with high CaO/MgO and CO2/(CO2 + H2O) ratios. Infiltration and storage of the metasomatic agents occurred in the former lower lithosphere, following continuous recycling of oceanic crust, comprising the release of Ca, CO2, H2O, further volatiles, and incompatible elements. Both volcanic episodes coincide with topographic uplift, erosion, rifting, and reactivation of lithosphere-scale faults, probably related to phases of strong mechanical coupling between Alpine orogen and European foreland. The first period overlapped with an era of prolonged N-directed intraplate compressional stress due to the Adriatic-Eurasian collision, provoking large-scale deformation, isostatic compensation, erosion, and consequent lithosphere thinning in the future CEVP. The second period is associated with the Oligocene–Miocene main stage of the European Cenozoic Rift System. Onset of volcanism was accompanied by a change in deformation in the Upper Rhine Graben from (W)NW extension to (E)NE extension and transtension by a complex interplay of evasive movements responding to shortening in Alps and Jura. Magma compositions, barely magmatic graben structures, volcanic activity outside rifts, and extensive exhumation suggest that in response to rifting, passive asthenospheric doming also contributed to magmatism by causing strong lithosphere–asthenosphere interaction and providing heat.
Failed airway management is the major contributor for anaesthesia-related morbidity and mortality. Cannot-intubate-cannot-ventilate scenarios are the most critical emergency in airway management, and ...belong to the worst imaginable scenarios in an anaesthetist's life. In such situations, apnoeic oxygenation might be useful to avoid hypoxaemia. Anaesthesia guidelines recommend careful preoxygenation and application of high flow oxygen in difficult intubation scenarios to prevent episodes of deoxygenation. In this study, we evaluated the decrease in oxygen concentration in a model when using different strategies of oxygenation: using a special oxygenation laryngoscope, nasal oxygen, nasal high flow oxygen, and control.
In this experimental study we compared no oxygen application as a control, standard pure oxygen application of 10 l·min
via nasal cannula, high flow 90% oxygen application at 20 l·min
using a special nasal high flow device, and pure oxygen application via our oxygenation laryngoscope at 10 l·min
. We preoxygenated a simulation lung to 97% oxygen concentration and connected this to the trachea of a manikin model simulating apnoeic oxygenation. Decrease in oxygen concentration in the simulation lung was measured continuously for 20 min.
Oxygen concentration in the simulation lung dropped from 97 ± 1% at baseline to 40 ± 1% in the no oxygen group, to 80 ± 1% in the standard nasal oxygen group, and to 73 ± 2% in the high flow nasal oxygenation group. However, it remained at 96 ± 0% in the oxygenation laryngoscope group (p < 0.001 between all groups).
In this technical simulation, oxygenation via oxygenation laryngoscope was more effective than standard oxygen insufflation via nasal cannula, which was more effective than nasal high flow insufflation of 90% oxygen.
Abstract
The Miocene Kaiserstuhl Volcanic Complex (Southwest Germany) consists largely of tephritic to phonolitic rocks, accompanied by minor nephelinitic to limburgitic and melilititic to haüynitic ...lithologies associated with carbonatites. Based on whole-rock geochemistry, petrography, mineralogy and mineral chemistry, combined with mineral equilibrium calculations and fractional crystallization models using the Least Square Fitting Method, we suggest that the Kaiserstuhl was fed by at least two distinct magma sources. The most primitive rock type of the tephritic to phonolitic group is rare monchiquite (basanitic lamprophyre) evolving towards tephrite, phonolitic tephrite, phonolitic noseanite, nosean phonolite and tephritic phonolite by fractional crystallization of variable amounts of clinopyroxene, amphibole, olivine, spinel/magnetite, garnet, titanite, plagioclase and nosean. During this evolution, temperature and silica activity (aSiO2) decrease from about 1100°C and aSiO2 = 0·6–0·8 to 880°C and aSiO2 = ∼0·2. At the same time, oxygen fugacity (fO2) increases from ΔFMQ* = +2–3 to ΔFMQ* = +3–5, with ΔFMQ* being defined as the log fO2 deviation from the silica activity-corrected FMQ buffer curve. Nephelinitic rocks probably derive by fractionation of mostly olivine, spinel/magnetite, melilite, perovskite and nepheline from an olivine melilititic magma. The nephelinitic rocks were formed at similarly high crystallization temperatures (>1000°C) and evolve towards limburgite (hyalo-nepheline basanite) by an increase of silica activity from about aSiO2 = 0·4–0·5 to aSiO2 = 0·5–0·9, whilst redox conditions are buffered to ΔFMQ* values of around +3. Haüyne melilitite and the more evolved (melilite) haüynite may equally be derived from an olivine melilitite by more intense olivine and less melilite fractionation combined with the accumulation of haüyne, clinopyroxene and spinel. These rocks were crystallized at very low silica activities (aSiO2 ≤0·2) and highly oxidized conditions (ΔFMQ* = +4–6). Even higher oxygen fugacities (ΔFMQ* = +6–7) determined for the carbonatite suggests a close genetic relation between these two groups. The assemblage of carbonatites with highly oxidized silicate rocks is typical of many carbonatite occurrences worldwide, at least for those associated with melilititic to nephelinitic silicate rocks. Therefore, we suggest that the existence of highly oxidized carbonate-bearing sublithospheric mantle domains is an important prerequisite to form such complexes.
Abstract
The Quaternary Tarosero volcano is situated in the East African Rift of northern Tanzania and mainly consists of trachyte lavas and some trachytic tuffs. In addition, there are minor ...occurrences of extrusive basalts, andesites and latites, as well as peralkaline trachytes, olivine trachytes and phonolites. Some of the peralkaline phonolites contain interstitial eudialyte, making Tarosero one of the few known occurrences for extrusive agpaitic rocks. This study investigates the genetic relationships between the various rock types and focuses on the peculiar formation conditions of the extrusive agpaitic rocks using a combination of whole-rock geochemistry, mineral chemistry, petrography, thermodynamic calculations, and major and trace element modelling. The Tarosero rocks formed at redox conditions around or below the fayalite–magnetite–quartz buffer (FMQ). During multi-level magmatic fractionation at depths between ∼40 km and the shallow crust, temperature decreased from >1100 °C at near-liquidus conditions in the basalts to ∼700 °C in the peralkaline residue. Fractional crystallization models and trace element characteristics do not indicate a simple genetic relationship between the trachytes and the other rock types at Tarosero. However, the genetic relationships between the primitive basalts and the intermediate latites can be explained by high-pressure fractional crystallization of olivine + clinopyroxene + magnetite + plagioclase + apatite. Further fractionation of these mineral phases in addition to amphibole and minor ilmenite led to the evolution towards the peralkaline trachytes and phonolites. The eudialyte-bearing varieties of the peralkaline phonolites required additional low-pressure fractionation of alkali feldspar and minor magnetite, amphibole and apatite. In contrast to the peralkaline trachytes and phonolites, the peralkaline olivine trachytes contain olivine instead of amphibole, thus indicating a magma evolution at even lower pressure conditions. They can be modelled as a derivation from the latites by fractional crystallization of plagioclase, clinopyroxene, magnetite and olivine. In general, agpaitic magmas evolve under closed-system conditions, which impede the escape of volatile phases. In the case of the extrusive agpaitic rocks at Tarosero, the early exsolution of fluids and halogens was prevented by a low water activity. This resulted in high concentrations of rare earth elements (REE) and other high field strength elements (HFSE) and the formation of eudialyte in the most evolved peralkaline phonolites. Within the peralkaline rock suite, the peralkaline olivine trachytes contain the lowest HFSE and REE concentrations, consistent with mineralogical evidence for formation at a relatively high water activity. The lack of amphibole fractionation, which can act as a water buffer of the melt, as well as the evolution at relatively low-pressure conditions caused the early exsolution of fluids and loss of water-soluble elements. This prevented a strong enrichment of HFSE and REE before the magma was finally extruded.
Apatite is ubiquitous in a wide range of magmatic rocks and its F–Cl–Br–S systematics can be used to decipher e.g., mixing processes within a magmatic complex and may give insights into fluid ...un-mixing and degassing processes during the emplacement and cooling of plutonic rocks.
In this study, we analyzed a F-apatite (Durango, Mexico), a Cl-apatite (Ødegården, Norway) and apatites from five plutonic samples from the alkaline Mt. Saint Hilaire Complex (Canada) by means of Electron Microprobe Analysis (EPMA), Laser Ablation ICP-MS (LA-ICP-MS), Secondary Ion Mass Spectrometry (SIMS), pyrohydrolysis combined with ion chromatography, Fourier Transformed Infrared Spectroscopy (FTIR), Instrumental Neutron Activation Analysis (INAA) and Total Reflection X-ray Fluorescence Analysis (TXRF).
The special focus of our study is Br, since the analytical possibilities for this element are especially in the low- to sub-μg/g range restricted and thus, reliable concentration data for Br in rock-forming minerals are scarce. We demonstrate here that TXRF, which is barely used in geosciences so far, is suitable for analyzing the bulk content of Br and Cl as well as of a range of important trace metals (e.g., Sr, Ce, Fe, Mn, As) in apatite simultaneously. The TXRF method combines the advantages of low to very low detection limits (μg/g- to sub-μg/g range), small sample amounts needed (mg range) and a relatively fast and inexpensive analytical procedure. Depending on the As content of apatite, reliable concentration data for Br can be produced with detection limits as low as 0.2
μg/g.
Using the Durango apatite as an internal reference material, SIMS analyses give consistent results with EPMA, INAA and TXRF and allow for detailed insights into the F–Cl–Br–S systematics of apatites. The presented data set reveals significant heterogeneities within and between different apatite grains from a single sample.
► Br concentrations for magmatic minerals are scarce. ► TXRF can be used to analyze the bulk Br content in apatite. ► A Br concentration of around 0.1
μg/g for the Durango apatite is proposed.
This study reports halogen contents (F and Cl) of amphibole and phlogopite derived from mantle xenoliths and one peridotite massif, for amphibole and phlogopite megacrysts and ultramafic magmatic ...cumulates (hornblendites) found in alkaline volcanic rocks from 12 localities in Europe and Africa. Amphibole and phlogopite contain more F than Cl with F/Cl ratios reaching about 160 in phlogopites and 50 in amphiboles. Phlogopites are higher in F (median of 3400 µg/g) than amphibole (median of 1000 µg/g), while median Cl contents are higher in amphibole (290 µg/g) compared to phlogopite (180 µg/g). The Cl contents and the F/Cl ratios in amphibole and phlogopite from mantle xenoliths exhibit large differences between samples of the same region, recording very large variations of halogen contents in the continental lithosphere. We suggest that the halogen content in such samples largely depends on the initial composition of percolating melts and fluids in the continental lithosphere. During reaction of these agents with peridotitic wall-rocks, Cl is preferentially retained in the fluid as it is much more incompatible compared to water and F. This desiccation effect continuously increases salinity (Cl content) and decreases the F/Cl ratio in the agent with time, causing variable Cl contents and F/Cl ratios in amphibole and phlogopite at a specific locality. Subsequent partial melting processes may then sequester and re-distribute, especially Cl among amphibole, phlogopite and melts/fluids as a result of its strong incompatibility, whereas F is much less affected as it behaves slightly compatible. The impact of even small amounts of amphibole and mica on the total halogen budget in the continental lithosphere is significant and both minerals can effectively contribute to the high halogen contents typical of alkaline melts.
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