Three tourmaline reference materials sourced from the Harvard Mineralogical and Geological Museum (schorl 112566, dravite 108796 and elbaite 98144), which are already widely used for the calibration ...of in situ boron isotope measurements, are characterised here for their oxygen and lithium isotope compositions. Homogeneity tests by secondary ion mass spectrometry (SIMS) showed that at sub‐nanogram test portion masses, their 18O/16O and 7Li/6Li isotope ratios are constant within ± 0.27‰ and ± 2.2‰ (1s), respectively. The lithium mass fractions of the three materials vary over three orders of magnitude. SIMS homogeneity tests showed variations in 7Li/28Si between 8% and 14% (1s), which provides a measure of the heterogeneity of the Li contents in these three materials. Here, we provide recommended values for δ18O, Δ’17O and δ7Li for the three Harvard tourmaline reference materials based on results from bulk mineral analyses from multiple, independent laboratories using laser‐ and stepwise fluorination gas mass spectrometry (for O), and solution multi‐collector inductively coupled plasma‐mass spectroscopy (for Li). These bulk data also allow us to assess the degree of inter‐laboratory bias that might be present in such data sets. This work also re‐evaluates the major element chemical composition of the materials by electron probe microanalysis and investigates these presence of a chemical matrix effect on SIMS instrumental mass fractionation with regard to δ18O determinations, which was found to be < 1.6‰ between these three materials. The final table presented here provides a summary of the isotope ratio values that we have determined for these three materials. Depending on their starting mass, either 128 or 512 splits have been produced of each material, assuring their availability for many years into the future.
Key Points
Three widely available tourmaline reference materials are characterized for δ7Li, δ17O and δ18O, while new EPMA and SIMS measurements refine their major element compositions.
SIMS data document homogeneity for these isotope ratios.
SIMS matrix effect causes bias of 1.9‰ between elbaite and schorl, whereas silicate glass shows even more severe bias.
Resistance to chemotherapy is ultimately responsible for the majority of AML-related deaths, making the identification of resistance pathways a high priority. Transcriptomics approaches can be used ...to identify genes regulated at the level of transcription or mRNA stability but miss microRNA-mediated changes in translation, which are known to play a role in chemo-resistance. To address this, we compared miRNA profiles in paired chemo-sensitive and chemo-resistant subclones of HL60 cells and used a bioinformatics approach to predict affected pathways. From a total of 38 KEGG pathways implicated, TGF-β/activin family signaling was selected for further study. Chemo-resistant HL60 cells showed an increased TGF-β response but were not rendered chemo-sensitive by specific inhibitors. Differential pathway expression in primary AML samples was then investigated at the RNA level using publically available gene expression data in the TGCA database and by longitudinal analysis of pre- and post-resistance samples available from a limited number of patients. This confirmed differential expression and activity of the TGF-β family signaling pathway upon relapse and revealed that the expression of TGF-β and activin signaling genes at diagnosis was associated with overall survival. Our focus on a matched pair of cytarabine sensitive and resistant sublines to identify miRNAs that are associated specifically with resistance, coupled with the use of pathway analysis to rank predicted targets, has thus identified the activin/TGF-β signaling cascade as a potential target for overcoming resistance in AML.
Facial ancestry can be described as variation that exists in facial features that are shared amongst members of a population due to environmental and genetic effects. Even within Europe, faces vary ...among subregions and may lead to confounding in genetic association studies if unaccounted for. Genetic studies use genetic principal components (PCs) to describe facial ancestry to circumvent this issue. Yet the phenotypic effect of these genetic PCs on the face has yet to be described, and phenotype-based alternatives compared. In anthropological studies, consensus faces are utilized as they depict a phenotypic, not genetic, ancestry effect. In this study, we explored the effects of regional differences on facial ancestry in 744 Europeans using genetic and anthropological approaches. Both showed similar ancestry effects between subgroups, localized mainly to the forehead, nose, and chin. Consensus faces explained the variation seen in only the first three genetic PCs, differing more in magnitude than shape change. Here we show only minor differences between the two methods and discuss a combined approach as a possible alternative for facial scan correction that is less cohort dependent, more replicable, non-linear, and can be made open access for use across research groups, enhancing future studies in this field.
The production of gas from unconventional resources became an important position in the world energy economics. In 2012, the European Commission's Joint Research Centre estimate 16 trillion cubic ...meters (Tcm) of technically recoverable shale gas in Europe. Taking into account that the exploitation of unconventional gas can be accompanied by serious health risks due to the release of toxic chemical components and natural occurring radionuclides into the return flow water and their near-surface accumulation in secondary precipitates, we investigated the release of U, Th and Ra from black shales by interaction with drilling fluids containing additives that are commonly employed for shale gas exploitation.
We performed leaching tests at elevated temperatures and pressures with an Alum black shale from Bornholm, Denmark and a Posidonia black shale from Lower Saxony, Germany. The Alum shale is a carbonate free black shale with pyrite and barite, containing 74.4 μg/g U. The Posidonia shales is a calcareous shale with pyrite but without detectable amounts of barite containing 3.6 μg/g U.
Pyrite oxidized during the tests forming sulfuric acid which lowered the pH on values between 2 and 3 of the extraction fluid from the Alum shale favoring a release of U from the Alum shale to the fluid during the short-term and in the beginning of the long-term experiments. The activity concentration of 238U is as high as 23.9 mBq/ml in the fluid for those experiments. The release of U and Th into the fluid is almost independent of pressure. The amount of uranium in the European shales is similar to that of the Marcellus Shale in the United States but the daughter product of 238U, the 226Ra activity concentrations in the experimentally derived leachates from the European shales are quite low in comparison to that found in industrially derived flowback fluids from the Marcellus shale. This difference could mainly be due to missing Cl in the reaction fluid used in our experiments and a lower fluid to solid ratio in the industrial plays than in the experiments due to subsequent fracking and minute cracks from which Ra can easily be released.
•Release of U and Th from European black shales experimentally studied.•Activity concentration of 238U and 226Ra from experimental fracturing fluids measured.•Amount of U in the European shales is similar to that of the Marcellus Shale (US).•Behaviour of U and Ra seems to be similar in experiments and production sites.•Preferential release of Ra from U-hosting (instead of Th) solids inferred.
Digital lesen Wilke, Franziska
2022, Letnik:
2
eBook
Odprti dostop
Was ist digitales Lesen? Wie gehen Lesende mit der digitalen Angebotsfülle um? Individuelle Bewältigungsmechanismen reichen oft nicht mehr aus, um diese Herausforderung zu meistern, und der Hype um ...digitale Medien verstellt den Blick auf ihre Tradition. Die Entwicklung stabiler Lesestrategien und Medienkompetenz erfordert daher eine systematische historische und wissenschaftliche Beschreibung des Phänomens. Aus der Synthese von Leseakttheorie, Materialitäts- und Medienforschung sowie Praxistheorie entwickelt Franziska Wilke eine Lesetypologie, die das Lesen digitaler Literatur veranschaulicht. Ihre gewonnenen Erkenntnisse nützen nicht nur Lesenden, sondern auch jenen, die es werden möchten.
Metamorphic and deformed rocks in thrust zones show particularly high seismic anisotropy causing challenges for seismic imaging and interpretation. A good example is the Seve Nappe Complex in central ...Sweden, an old exhumed orogenic thrust zone that is characterized by a strong but incoherent seismic reflectivity and considerable seismic anisotropy. However, only little is known about their origin in relation to composition and structural influences on measurements at different seismic scales. Here, we present a new integrative study of cross‐scale seismic anisotropy analyses combining mineralogical composition, microstructural analyses, and seismic laboratory experiments from the COSC‐1 borehole, which sampled a 2.5‐km‐deep section of metamorphic rocks deformed in an orogenic root now preserved in the Lower Seve Nappe. While there is strong crystallographic preferred orientation in most samples in general, variations in anisotropy depend mostly on bulk mineral composition and dominant core lithology as shown by a strong correlation between these. This relationship enables to identify three distinct seismic anisotropy facies providing a continuous anisotropy profile along the borehole. Moreover, comparison of laboratory seismic measurements and electron‐backscatter diffraction data reveals a strong scale dependence, which is more pronounced in the highly deformed, heterogeneous samples. This highlights the need for comprehensive cross‐validation of microscale anisotropy analyses with additional lithological data when integrating seismic anisotropy over seismic scales.
Key Points
Integrated study of seismic anisotropy in metamorphic rocks from the COSC‐1 borehole in the Swedish Caledonides
Macroscale anisotropy is driven by major mineral assemblage, while modeled anisotropy dependent on microscale heterogeneity
Results enable to derive facies‐based anisotropy model from core lithology to be compared with field data
Metabasites were sampled from rock series of the subducted margin of the Indian Plate, the so-called Higher Himalayan Crystalline, in the Upper Kaghan Valley, Pakistan. These vary from corona ...dolerites, cropping out around Saif-ul-Muluk in the south, to coesite–eclogite close to the suture zone against rocks of the Kohistan arc in the north. Bulk rock major- and trace- element chemistry reveals essentially a single protolith as the source for five different eclogite types, which differ in fabric, modal mineralogy as well as in mineral chemistry. The study of newly-collected samples reveals coesite (confirmed by in situ Raman spectroscopy) in both garnet and omphacite. All eclogites show growth of amphiboles during exhumation. Within some coesite-bearing eclogites the presence of glaucophane cores to barroisite is noted whereas in most samples porphyroblastic sodic–calcic amphiboles are rimmed by more aluminous calcic amphibole (pargasite, tschermakite, and edenite). Eclogite facies rutile is replaced by ilmenite which itself is commonly surrounded by titanite. In addition, some eclogite bodies show leucocratic segregations containing phengite, quartz, zoisite and/or kyanite. The important implication is that the complex exhumation path shows stages of initial cooling during decompression (formation of glaucophane) followed by reheating: a very similar situation to that reported for the coesite-bearing eclogite series of the Tso Morari massif, India, 450 km to the south-east.
The large volumes and unknown composition of flowback and produced waters cause public concerns about the environmental and social compatibility of hydraulic fracturing and the exploitation of ...unconventional gas. Flowback and produced waters contain not only residues of fracking additives but also chemical species that are dissolved from the shales. Interactions of different shales with an artificial fracturing fluid were studied in lab experiments under ambient and elevated temperature and pressure conditions. Fluid-rock interactions change the chemical composition of the fracturing fluid and this indicates that geochemistry of the fractured shale needs to be considered to understand flowback water composition.
When measuring boron (B) in tourmalines calibrated with schorl, no deviations in
the peak intensities could be detected with a proven analysis protocol and
using the Mo/B4C multilayer crystal LDEB. ...It is only when boron is detected
in natural and experimental samples, some with significantly lower boron
concentrations than in tourmalines, that irregularities in the analysis
become visible. This phenomenon is known but has not been analytically
investigated so far. Using four natural and artificial solids with boron
concentrations from 0.035 wt %–3.14 wt % B, an apparent linear trend line was
drawn. The intersect of that trend line with the y axis represents the
detection limit of boron, which is of about 0.25 wt % B. The discrepancy
between the apparent and the true value trend lines at boron concentrations of
0.25 wt %–2.1 wt % B shows that a correction is necessary. At higher boron
concentrations, the discrepancy between the apparent and true value
trend lines is within the uncertainty of electron microprobe analysis (EPMA) and disappears
completely up to boron concentrations of about 3 wt %.
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