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Mosaic crystals, with their high integrated reflectivities, are widely employed in spectrometers used to diagnose high energy density systems. X-ray Thomson scattering (XRTS) has emerged as a powerful diagnostic tool of these systems, providing in principle direct access to important properties such as the temperature via detailed balance. However, the measured XRTS spectrum is broadened by the spectrometer instrument function (IF), and without careful consideration of the IF one risks misdiagnosing system conditions. Here, we consider in detail the IF of 40 and 100 μ m mosaic Highly Annealed Pyrolytic Graphite crystals, and how the broadening varies across the spectrometer in an energy range of 6.7–8.6 keV. Notably, we find a strong asymmetry in the shape of the IF toward higher energies. As an example, we consider the effect of the asymmetry in the IF on the temperature inferred via XRTS for simulated 80 eV CH plasmas and find that the temperature can be overestimated if an approximate symmetric IF is used. We, therefore, expect a detailed consideration of the full IF will have an important impact on system properties inferred via XRTS in both forward modeling and model-free approaches. [ABSTRACT FROM AUTHOR]

A new diamond anvil cell experimental approach has been implemented at the European x-ray Free Electron Laser, combining pulsed laser heating with MHz x-ray diffraction. Here, we use this setup to determine liquidus temperatures under extreme conditions, based on the determination of time-resolved crystallization. The focus is on a Fe-Si-O ternary system, relevant for planetary cores. This time-resolved diagnostic is complemented by a finite-element model, reproducing temporal temperature profiles measured experimentally using streaked optical pyrometry. This model calculates the temperature and strain fields by including (i) pressure and temperature dependencies of material properties, and (ii) the heat-induced thermal stress, including feedback effect on material parameter variations. Making our model more realistic, these improvements are critical as they give 7000 K temperature differences compared to previous models. Laser intensities are determined by seeking minimal deviation between measured and modeled temperatures. Combining models and streak optical pyrometry data extends temperature determination below detection limit. The presented approach can be used to infer the liquidus temperature by the appearance of SiO 2 diffraction spots. In addition, temperatures obtained by the model agree with crystallization temperatures reported for Fe–Si alloys. Our model reproduces the planetary relevant experimental conditions, providing temperature, pressure, and volume conditions. Those predictions are then used to determine liquidus temperatures at experimental timescales where chemical migration is limited. This synergy of novel time-resolved experiments and finite-element modeling pushes further the interpretation capabilities in diamond anvil cell experiments. [ABSTRACT FROM AUTHOR]

The thermal conductivity of bridgmanite, the primary constituent of the Earth's lower mantle, has been investigated using diamond anvil cells at pressures up to 85 GPa and temperatures up to 3,100 K. We report the results of time‐domain optical laser flash heating and X‐ray Free Electron Laser heating experiments from a variety of bridgmanite samples with different Al and Fe contents. The results demonstrate that Fe or Fe,Al incorporation in bridgmanite reduces thermal conductivity by about 50% in comparison to end‐member MgSiO3 at the pressure‐temperature conditions of Earth's lower mantle. The effect of temperature on the thermal conductivity at 28–60 GPa is moderate, well described as k=k300(300/T)a ${k={k}_{300}(300/T)}^{a}$, where a is 0.2–0.5. The results yield thermal conductivity of 7.5–15 W/(m × K) in the thermal boundary layer of the lowermost mantle composed of Fe,Al‐bearing bridgmanite. Plain Language Summary: Heat transport from the Earth's core and mantle to the surface drives plate tectonics and is crucial for sustaining the magnetic field which shields the surface from the solar wind. To quantify the heat transport process across the core‐mantle boundary layer, it is important to know thermal conductivity of major constituent minerals of the lower mantle in the region. Bridgmanite, which was called silicate perovskite, is the most abundant mineral in the lower mantle. Here we measured thermal conductivity on lab‐grown bridgmanite with different Fe and Al compositions compressed at the tips of two opposing diamonds to reproduce relevant pressures in the mantle. To obtain thermal conductivity, we applied optical and X‐ray Free Electron Lasers combined with optical spectroscopy and X‐ray diffraction to heat and measure time‐dependent temperature distributions of the sample. Our study provides relevant high pressure‐temperature data sets to better constrain the heat flux across the core‐mantle boundary. Key Points: We measured thermal conductivity of Fe,Al‐bearing bridgmanite, the most abundant mineral in the Earth's lower mantle, up to 85 GPa and 3,100 KFinite‐element calculations to temperatures obtained from laser flash and X‐ray Free Electron Laser heating measurements are fitted to evaluate temperature effect on conductivityWe assessed pressure, temperature, composition effects on thermal conductivity of bridgmanite at the thermal boundary layer of the lowermost mantle [ABSTRACT FROM AUTHOR]

An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (-103 s-1), where up to 352 diffraction images can be collected from a single pulse train. The set-up employs piezo-driven dDACs capable of compressing samples in -340 ms, compatible with the maximum length of the pulse train (550 ms). Results from rapid compression experiments on a wide range of sample systems with different X-ray scattering powers are presented. A maximum compression rate of 87 TPa s-1 was observed during the fast compression of Au, while a strain rate of -1100 s-1 was achieved during the rapid compression of N2 at 23 TPa s1. [ABSTRACT FROM AUTHOR]

The application of fluorescent crystal media in wide-range X-ray detectors provides an opportunity to directly image the spatial distribution of ultraintense X-ray beams including investigation of the focal spot of free-electron lasers. Here the capabilities of the micro- and nano-focusing X-ray refractive optics available at the High Energy Density instrument of the European XFEL are reported, as measured in situ by means of a LiF fluorescent detector placed into and around the beam caustic. The intensity distribution of the beam focused down to several hundred nanometers was imaged at 9 keV photon energy. A deviation from the parabolic surface in a stack of nanofocusing Be compound refractive lenses (CRLs) was found to affect the resulting intensity distribution within the beam. Comparison of experimental patterns in the far field with patterns calculated for different CRL lens imperfections allowed the overall inhomogeneity in the CRL stack to be estimated. The precise determination of the focal spot size and shape on a sub-micrometer level is essential for a number of high energy density studies requiring either a pin-size backlighting spot or extreme intensities for X-ray heating. [ABSTRACT FROM AUTHOR]

The heat shock response of dnaK, dnaJ, groEL, members of dnaK operon, and ftsH genes in Lactococcus lactis induces transcription of corresponding mRNA(s). Levels of mRNA in the first three show an increase for up to 15 minutes after heat shock, but decrease after 20 minutes. In orf1 and grpE, there is maximum induction within 10 minutes and it is maintained till after 15 minutes. There is a significant induction after 10 minutes in ftsH gene that is observed after 20 minutes. No induction is observed in orf4.

The European XFEL delivers up to 27000 intense (>1012 photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X‐ray radiation, at a maximum repetition rate of 4.5 MHz. Its unique X‐ray beam parameters enable groundbreaking experiments in matter at extreme conditions at the High Energy Density (HED) scientific instrument. The performance of the HED instrument during its first two years of operation, its scientific remit, as well as ongoing installations towards full operation are presented. Scientific goals of HED include the investigation of extreme states of matter created by intense laser pulses, diamond anvil cells, or pulsed magnets, and ultrafast X‐ray methods that allow their diagnosis using self‐amplified spontaneous emission between 5 and 25 keV, coupled with X‐ray monochromators and optional seeded beam operation. The HED instrument provides two target chambers, X‐ray spectrometers for emission and scattering, X‐ray detectors, and a timing tool to correct for residual timing jitter between laser and X‐ray pulses. [ABSTRACT FROM AUTHOR]

The response of forsterite, Mg2SiO4, under dynamic compression is of fundamental importance for understanding its phase transformations and high‐pressure behavior. Here, we have carried out an in situ X‐ray diffraction study of laser‐shocked polycrystalline and single‐crystal forsterite (a‐, b‐, and c‐orientations) from 19 to 122 GPa using the Matter in Extreme Conditions end‐station of the Linac Coherent Light Source. Under laser‐based shock loading, forsterite does not transform to the high‐pressure equilibrium assemblage of MgSiO3 bridgmanite and MgO periclase, as has been suggested previously. Instead, we observe forsterite and forsterite III, a metastable polymorph of Mg2SiO4, coexisting in a mixed‐phase region from 33 to 75 GPa for both polycrystalline and single‐crystal samples. Densities inferred from X‐ray diffraction data are consistent with earlier gas‐gun shock data. At higher stress, the response is sample‐dependent. Polycrystalline samples undergo amorphization above 79 GPa. For [010]‐ and [001]‐oriented crystals, a mixture of crystalline and amorphous material is observed to 108 GPa, whereas the [100]‐oriented forsterite adopts an unknown phase at 122 GPa. The first two sharp diffraction peaks of amorphous Mg2SiO4 show a similar trend with compression as those observed for MgSiO3 in both recent static‐ and laser‐driven shock experiments. Upon release to ambient pressure, all samples retain or revert to forsterite with evidence for amorphous material also present in some cases. This study demonstrates the utility of femtosecond free‐electron laser X‐ray sources for probing the temporal evolution of high‐pressure silicate structures through the nanosecond‐scale events of shock compression and release. Key Points: The phases occurring along the Hugoniots of forsterite are identified from 19 to 122 GPaBetween 33 and 75 GPa, forsterite and forsterite III coexist for both single‐crystal and polycrystalline samplesAt higher shock stress, variable degrees of amorphization are observed with different onset stresses for polycrystals and single crystals [ABSTRACT FROM AUTHOR]

The high-pressure phase transition of strontianite (SrCO3) was investigated at ambient temperature by means of powder and single-crystal X-ray diffraction. The samples were compressed in a diamond anvil cell to a maximum pressure of 49 GPa. Structure refinements confirm the existence of SrCO3 in the low pressure aragonite-type phase Pmcn (62) up to about 26 GPa. Above this pressure, SrCO3 transforms into a high-pressure phase with post-aragonite crystal structure Pmmn (59). Fitting the volume extracted from the compression data to the third-order Birch-Murnaghan equation of state for the low-pressure phase of SrCO3 yields K0 = 62:7.6/ GPa and K00 D 3:2.1/, and for the high-pressure phase this yields K0 = 103.10/ GPa and K00 D 2:3.6/. The unit cell parameters change non-uniformly, with the c axis being 4 times more compressible than the a and b axes. Our results unequivocally show the existence of a Pmmn structure in SrCO3 above 26 GPa and provide important structural parameters for this phase. [ABSTRACT FROM AUTHOR]

Background: Choosing Wisely Canada is an initiative to reduce overprescribing and overtesting. This study assessed adherence to 4 Choosing Wisely Canada recommendations for interventions commonly performed in primary care: (a) antibiotic prescriptions for infections that are probably viral in origin, (b) routine vitamin D tests in low-risk adults, (c) annual screening blood tests and (d) prescriptions of antipsychotic medication to treat symptoms of dementia. Methods: We conducted a retrospective cohort study of data from the electronic medical records of patients who had an encounter between 2014 and 2016 with a participating Manitoba Primary Care Research Network primary care provider in Manitoba, Canada. Patient encounter data were reviewed for prescribing and testing practices. Descriptive statistics and multivariable models assessed associations between patient and provider characteristics and rates of prescribing and testing. Results: Data for 164 195 patients from 230 providers were included in the study. Sixteen percent (n = 25 629) of patients had an encounter that involved potentially unnecessary diagnostic testing and treatment. A minority of providers contributed to above-average rates of prescribing and testing: 29% (n = 69) of providers prescribed antibiotics for a viral indication,11% (n = 24) prescribed an antipsychotic to a patient diagnosed with dementia, 9% (n = 24) ordered prostate-specific antigen tests and 14% (n = 34) ordered vitamin D tests at above-average rates, respectively. Patient and provider characteristics were associated with each of the prescribing and testing practices assessed. Interpretation: This study demonstrated that fewer than 30% of primary care providers contributed to interventions in direct contradiction to Choosing Wisely Canada recommendations. Improvement strategies specific to each prescription or testing recommendation should target specific providers to prevent patient harm and reduce unnecessary health care spending. [ABSTRACT FROM AUTHOR]

Over the past several decades the oeuvre of Rembrandt has been the subject of extensive art historical and scientific investigations. One of the most striking features to emerge is his frequent re-use of canvases and panels. The painting An Old Man in Military Costume (78.PB.246), in the collection of the J. Paul Getty Museum, is an example of such a re-used panel. Conventional imaging techniques revealed the presence of a second portrait under the surface portrait, but the details of this hidden portrait have not yet been revealed. Vermilion (HgS) has been identified to have been used nearly exclusively in the flesh tones of the lower painting, suggesting that element-specific XRF imaging might successfully image the hidden portrait. To test this hypothesis, a full-scale mock-up of the painting was created, including a “free impression” of the hidden portrait, reproducing as closely as possible the pigments and paint stratigraphy of the original painting. XRF imaging of the mock-up painting was conducted using three different XRF imaging systems: a mobile X-ray tube based system and two synchrotron-based setups (one equipped with multiple SDDs and one equipped with a Maia detector). The sensitivity, limits of detection and imaging capabilities of each system under the chosen experimental conditions are evaluated and compared. The results indicate that an investigation of the original painting by this method would have an excellent chance of success. [ABSTRACT FROM AUTHOR]

The assemblage strontium anorthite, quartz, and kyanite was reacted with H2O+CaCl2 solutions at 500 °C and pressures between 460 and ~1300 MPa using a hydrothermal diamond-anvil cell. Information on the kinetics was obtained in situ based on time-resolved synchrotron-radiation X-ray fluorescence analyses of the Sr concentration in the fluid. The reaction products (anorthite or zoisite) were studied using transmission electron microscopy to obtain information on the reaction mechanism and mineral-fluid partitioning of strontium. The time required for equilibration was primarily controlled by the reaction mechanism, but not discernibly affected by pressure or chloride concentration. Nucleation and growth of zoisite at the expense of strontium anorthite was much faster than the Sr-Ca exchange reaction of strontium anorthite to anorthite, and resulted in chemically homogeneous crystals. The anorthite had developed a high nanoporosity during the reaction, which is indicative of coupled dissolution-precipitation. A zoisite-fluid exchange coefficient ... was obtained for the Sr-Ca fractionation at 500 °C and ~1300 MPa. At low bulk Sr/Ca, this value is in very good agreement with literature data, which are based on zoisite syntheses from oxide and hydroxide mixtures in chloridic fluids at 600 °C, 2 GPa and analyses after quench. This suggests that the Ca-Sr ratios in fluid and zoisite were not affected by back reactions during quenching. The constrained anorthite-fluid Sr partition coefficient for 500 °C, 460 MPa is, likewise, consistent with literature data, but determination of mineral-fluid partition and exchange coefficients can be hampered by quench phases in nanopores if coupled dissolution-precipitation acted as reaction mechanism. [ABSTRACT FROM AUTHOR]

The article presents a study that discusses the use of diamond-anvil cells (DACs) aimed at improving micro-XRF and XAFS experiments. It mentions that a confocal set-up has been established to enhance the quality of the fluorescence and XAFS spectra. It affirms that the result shows that the set-up suppresses signal from outside the sample chamber and creates excitation of fluorescence from the body of the DAC.

Large explosive volcanic eruptions inject gases, aerosols, and fine ashes into the stratosphere, potentially influencing climate and atmosphere composition on a global scale. Although the potential climate effect of chlorine (Cl) and bromine (Br) injections into the stratosphere is known, the global mass fluxes are poorly constrained. In this study we focus on the magmatic degassing systematics and budgets of Br and Cl, and on constraining the major sources of Br in a subduction setting. We therefore present a regional time series of Br and Cl emissions from 29 highly explosive eruptions throughout the Central American Volcanic Arc (CAVA), covering the last 200 ka, and a range of magmatic compositions and eruption magnitudes. We have measured Br and Cl in matrix glasses and melt inclusions using synchrotron radiation micro X-ray fluorescence spectrometry (SR micro-XRF) and electron microprobe, respectively. Melt inclusions of the CAVA tephras generally have higher Br (0.9 to 17.9 ppm) and Cl (770 to 3800 ppm) contents than the matrix glasses (0.39 to 1.5 ppm Br, 600 to 2800 ppm Cl). Moreover, the difference between maximum and minimum concentrations observed in melt inclusions of a given sample ranges between 9 and 90% of the maximum observed concentration for Br, and between 2 and 40% for Cl. Such intra-sample variations arise from variable pre-eruptive degassing of these halogens into a magmatic fluid phase. The relative loss of Br from the melt is 4 to 68 times higher than that of Cl. The masses of Br (2–1100 kt) and Cl (0.1 to 800 Mt) emitted by the eruptions generate instantaneous additions to the stratosphere potentially amounting to ∼6–5600% of the present-day stratospheric annual global loading of Equivalent Effective Stratospheric Chlorine. As the size of the stratospheric impact is primarily a function of eruption magnitude, we use magnitude-frequency relationships to estimate that eruptions adding ∼10% to resident EESC loading would occur every <40 years while every ∼200 years an eruption would double the EESC loading. Comparing the variations in Br and Cl concentrations and particularly minimum Cl/Br ratios in melt inclusions with geochemical trace-element proxies (e.g. U/La, Ba/Th) and lead-isotope compositions, which change along the arc in response to changing subduction conditions, we suggest that subducted calcareous sediment is a major source of magmatic Br but also infer an important role of fluids expelled from serpentinized subducted mantle. Extrapolation of CAVA volcanic Br emissions to the global subduction system thus needs to consider variations in the nature of subducted lithologies. [ABSTRACT FROM AUTHOR]

Abstract: A quantification tool for energy-dispersive X-ray fluorescence (ED-XRF) spectral data is presented, based on the application of Monte Carlo simulations in an iterative, inverse manner. Acting as an open-source plug-in to the widespread PyMca package, it provides users with a superior alternative to the fundamental parameter method based built-in quantification tool, taking into account higher order interactions, M-lines and cascade effects. Examples are shown demonstrating the usefulness of our implementation through data recorded at the synchrotron X-ray fluorescence microprobe installed at the HASYLAB Beamline L, Hamburg, Germany. [Copyright &y& Elsevier]

Abstract: Zircon is an important host mineral for many high-field strength elements (HFSE), particularly Zr and Hf. Thus, its solubility in geologic fluids at high pressure and temperature plays an important role in terrestrial cycling of these elements during processes in the Earth''s crust and mantle. We performed in-situ high-pressure, high-temperature measurements of zircon solubility in H2O–Na2Si3O7, H2O–Na2Si3O7+Al2O3, H2O–Na2Si2O5, H2O–NaAlSi3O8 fluids, as well as of baddeleyite solubility in H2O–NaOH fluids, by in-situ synchrotron radiation X-ray fluorescence analysis using hydrothermal diamond-anvil cells. Zirconium complexation in fluids in equilibrium with zircon was constrained by in-situ X-ray absorption near-edge structure (XANES) spectroscopy. Zircon solubility is strongly enhanced by addition of Na2Si3O7 to H2O. The degree of enhancement increases with Na2Si3O7 concentration. The Zr content of fluids containing 10wt% Na2Si3O7 reached up to 86±2ppm Zr at 550°C and 400MPa. At 30wt% Na2Si3O7, the maximum Zr concentration was 997±6ppm at 600°C and 440MPa. Zircon solubility in these fluids decreases considerably with pressure and increases slightly with temperature. Addition of Al2O3 decreases the zircon solubility. In H2O–NaAlSi3O8 fluids, the Zr concentrations are in the sub-ppm to ppm range. Zr concentrations in NaOH solutions in equilibrium with baddeleyite reached up to 390±2ppm at 600°C and 930MPa and increase with pressure and temperature. In-situ XANES spectra collected on Zr in H2O–Na2Si3O7, H2O–Na2Si3O7+Al2O3, H2O–NaOH, and H2O–HCl fluids in equilibrium with zircon provide evidence for strong differences in the Zr complexation between these fluids. Comparison of XANES spectra to those of model compounds and ab-initio simulation of XANES spectra revealed [8]Zr for the HCl solution, [7]Zr for the NaOH solution, and [6]Zr for the Na–Al-silicate-bearing solutions. For the latter solutions, formation of alkali zircono-silicate complexes is indicated by the strong dependence of zircon solubility on Na/Al and the similarity of the XANES spectra to spectra simulated based on the local structure around Zr in the alkali zircono-silicates vlasovite and catapleite. Alkali zircono-silicate complexes are responsible for the enhancement of Zr concentrations in Na–Al-silicate-bearing solutions and very likely play an important role for mobilization of HFSE during fluid–rock interaction. Because high alkali/Al can be expected in aqueous fluids at high pressure and temperature due to incongruent dissolution of feldspar and mica, the increase of zircon solubility along the NaAlSi3O8–Na2Si3O7 join points to potentially considerable Zr or HFSE transport by silicate-bearing aqueous fluids in the lower crust and upper mantle. [Copyright &y& Elsevier]

Abstract: A general Monte Carlo code for the simulation of energy dispersive X-ray fluorescence (ED-XRF) spectrometers is presented. As a significant extension to existing Monte Carlo codes, dedicated to ED-XRF spectrometers, the new code includes several unique features such as the simulation of M-lines and cascade effects. The detector response function was extended with fluorescence and Compton escape peaks, as well as with pulse pile-up. A full description of the underlying algorithms is given. The software was validated by means of comparison with experimental spectra of standard reference materials collected at the synchrotron XRF-microprobe installed at HASYLAB Beamline L, Hamburg, Germany. [Copyright &y& Elsevier]