Iron coordination in liquid FeAl2O4.

The structure of aerodynamically levitated liquid [Formula: see text] was measured by neutron diffraction with isotope substitution (NDIS). Classical and ab initio molecular dynamics simulations were performed and their results were found to be in close agreement with each other and the NDIS data. The results reveal that molten [Formula: see text] may be considered as an ionic liquid without any preference for particular short-range structural motifs. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Slab melting as a barrier to deep carbon subduction.

Interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time, moderating atmospheric composition and maintaining a life-supporting planet. While volcanoes expel volatile components into surface reservoirs, subduction of oceanic crust is responsible for replenishment of mantle reservoirs. Many natural, 'superdeep' diamonds originating in the deep upper mantle and transition zone host mineral inclusions, indicating an affinity to subducted oceanic crust. Here we show that the majority of slab geotherms will intersect a deep depression along the melting curve of carbonated oceanic crust at depths of approximately 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle. Low-degree partial melts are alkaline carbonatites that are highly reactive with reduced ambient mantle, producing diamond. Many inclusions in superdeep diamonds are best explained by carbonate melt-peridotite reaction. A deep carbon barrier may dominate the recycling of carbon in the mantle and contribute to chemical and isotopic heterogeneity of the mantle reservoir.

The Influence of Glacial Cover on Riverine Silicon and Iron Exports in Chilean Patagonia.

Glaciated environments have been highlighted as important sources of bioavailable nutrients, with inputs of glacial meltwater potentially influencing productivity in downstream ecosystems. However, it is currently unclear how riverine nutrient concentrations vary across a spectrum of glacial cover, making it challenging to accurately predict how terrestrial fluxes will change with continued glacial retreat. Using 40 rivers in Chilean Patagonia as a unique natural laboratory, we investigate how glacial cover affects riverine Si and Fe concentrations, and infer how exports of these bioessential nutrients may change in the future. Dissolved Si (as silicic acid) and soluble Fe (<0.02 µm) concentrations were relatively low in glacier-fed rivers, whereas concentrations of colloidal-nanoparticulate (0.02-0.45 µm) Si and Fe increased significantly as a function of glacial cover. These colloidal-nanoparticulate phases were predominately composed of aluminosilicates and Fe-oxyhydroxides, highlighting the need for size-fractionated analyses and further research to quantify the lability of colloidal-nanoparticulate species. We also demonstrate the importance of reactive particulate (>0.45 µm) phases of both Si and Fe, which are not typically accounted for in terrestrial nutrient budgets but can dominate riverine exports. Dissolved Si and soluble Fe yield estimates showed no trend with glacial cover, suggesting no significant change in total exports with continued glacial retreat. However, yields of colloidal-nanoparticulate and reactive sediment-bound Si and Fe were an order of magnitude greater in highly glaciated catchments and showed significant positive correlations with glacial cover. As such, regional-scale exports of these phases are likely to decrease as glacial cover disappears across Chilean Patagonia, with potential implications for downstream ecosystems.

Clinical spectrum and features of activated phosphoinositide 3-kinase δ syndrome: A large patient cohort study.

BACKGROUND: Activated phosphoinositide 3-kinase δ syndrome (APDS) is a recently described combined immunodeficiency resulting from gain-of-function mutations in PIK3CD, the gene encoding the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ). OBJECTIVE: We sought to review the clinical, immunologic, histopathologic, and radiologic features of APDS in a large genetically defined international cohort. METHODS: We applied a clinical questionnaire and performed review of medical notes, radiology, histopathology, and laboratory investigations of 53 patients with APDS. RESULTS: Recurrent sinopulmonary infections (98%) and nonneoplastic lymphoproliferation (75%) were common, often from childhood. Other significant complications included herpesvirus infections (49%), autoinflammatory disease (34%), and lymphoma (13%). Unexpectedly, neurodevelopmental delay occurred in 19% of the cohort, suggesting a role for PI3Kδ in the central nervous system; consistent with this, PI3Kδ is broadly expressed in the developing murine central nervous system. Thoracic imaging revealed high rates of mosaic attenuation (90%) and bronchiectasis (60%). Increased IgM levels (78%), IgG deficiency (43%), and CD4 lymphopenia (84%) were significant immunologic features. No immunologic marker reliably predicted clinical severity, which ranged from asymptomatic to death in early childhood. The majority of patients received immunoglobulin replacement and antibiotic prophylaxis, and 5 patients underwent hematopoietic stem cell transplantation. Five patients died from complications of APDS. CONCLUSION: APDS is a combined immunodeficiency with multiple clinical manifestations, many with incomplete penetrance and others with variable expressivity. The severity of complications in some patients supports consideration of hematopoietic stem cell transplantation for severe childhood disease. Clinical trials of selective PI3Kδ inhibitors offer new prospects for APDS treatment.

Direct observation of degassing during decompression of basaltic magma.

Transitions in eruptive style during volcanic eruptions strongly depend on how easily gas and magma decouple during ascent. Stronger gas-melt coupling favors highly explosive eruptions, whereas weaker coupling promotes lava fountaining and lava flows. The mechanisms producing these transitions are still poorly understood because of a lack of direct observations of bubble dynamics under natural magmatic conditions. Here, we combine x-ray radiography with a novel high-pressure/high-temperature apparatus to observe and quantify in real-time bubble growth and coalescence in basaltic magmas from 100 megapascals to surface. For low-viscosity magmas, bubbles coalesce and recover a spherical shape within 3 seconds, implying that, for lava fountaining activity, gas and melt remain coupled during the ascent up to the last hundred meters of the conduit. For higher-viscosity magmas, recovery times become longer, promoting connected bubble pathways. This apparatus opens frontiers in unraveling magmatic/volcanic processes, leading to improved hazard assessment and risk mitigation.

Unsupervised home spirometry is not equivalent to supervised clinic spirometry in children and young people with cystic fibrosis: Results from the CLIMB-CF study.

BACKGROUND: Handheld spirometry allows monitoring of lung function at home, of particular importance during the COVID-19 pandemic. Pediatric studies are unclear on whether values are interchangeable with traditional, clinic-based spirometry. We aimed to assess differences between contemporaneous, home (unsupervised) and clinic (supervised) spirometry and the variability of the former. The accuracy of the commercially available spirometer used in the study was also tested. METHODS: Data from participants in the Clinical Monitoring and Biomarkers to stratify severity and predict outcomes in children with cystic fibrosisc (CLIMB-CF) Study aged ≥ 6 years who had paired (±1 day) clinic and home forced expiratory volume in 1 s (FEV1 ) readings were analyzed. Variability during clinical stability over 6-months was assessed. Four devices from Vitalograph were tested using 1 and 3 L calibration syringes. RESULTS: Sixty-seven participants (median [interquartile range] age 10.7 [7.6-13.9] years) provided home and clinic FEV1 data pairs. The mean (SD) FEV1 % bias was 6.5% [±8.2%]) with wide limits of agreement (-9.6% to +22.7%); 76.2% of participants recorded lower results at home. Coefficient of variation of home FEV1 % during stable periods was 9.9%. Data from the testing of the handheld device used in CLIMB-CF showed a potential underread. CONCLUSION: In children and adolescents, home spirometry using hand-held equipment cannot be used interchangeably with clinic spirometry. Home spirometry is moderately variable during clinical stability. New handheld devices underread, particularly at lower volumes of potential clinical significance for smaller patients; this suggests that supervision does not account fully for the discrepancy. Opportunities should be taken to obtain dual device measurements in clinic, so that trend data from home can be utilized more accurately.

Dendritic crystallization in hydrous basaltic magmas controls magma mobility within the Earth's crust.

The majority of basaltic magmas stall in the Earth's crust as a result of the rheological evolution caused by crystallization during transport. However, the relationships between crystallinity, rheology and eruptibility remain uncertain because it is difficult to observe dynamic magma crystallization in real time. Here, we present in-situ 4D data for crystal growth kinetics and the textural evolution of pyroxene during crystallization of trachybasaltic magmas in high-temperature experiments under water-saturated conditions at crustal pressures. We observe dendritic growth of pyroxene on initially euhedral cores, and a surprisingly rapid increase in crystal fraction and aspect ratio at undercooling ≥30 °C. Rapid dendritic crystallization favours a rheological transition from Newtonian to non-Newtonian behaviour within minutes. We use a numerical model to quantify the impact of rapid dendritic crystallization on basaltic dike propagation, and demonstrate its dramatic effect on magma mobility and eruptibility. Our results provide insights into the processes that control whether intrusions lead to eruption or not.

In situ observation of nanolite growth in volcanic melt: A driving force for explosive eruptions.

Although gas exsolution is a major driving force behind explosive volcanic eruptions, viscosity is critical in controlling the escape of bubbles and switching between explosive and effusive behavior. Temperature and composition control melt viscosity, but crystallization above a critical volume (>30 volume %) can lock up the magma, triggering an explosion. Here, we present an alternative to this well-established paradigm by showing how an unexpectedly small volume of nano-sized crystals can cause a disproportionate increase in magma viscosity. Our in situ observations on a basaltic melt, rheological measurements in an analog system, and modeling demonstrate how just a few volume % of nanolites results in a marked increase in viscosity above the critical value needed for explosive fragmentation, even for a low-viscosity melt. Images of nanolites from low-viscosity explosive eruptions and an experimentally produced basaltic pumice show syn-eruptive growth, possibly nucleating a high bubble number density.

Molybdenum systematics of subducted crust record reactive fluid flow from underlying slab serpentine dehydration.

Fluids liberated from subducting slabs are critical in global geochemical cycles. We investigate the behaviour of Mo during slab dehydration using two suites of exhumed fragments of subducted, oceanic lithosphere. Our samples display a positive correlation of δ98/95MoNIST 3134 with Mo/Ce, from compositions close to typical mantle (-0.2‰ and 0.03, respectively) to very low values of both δ98/95MoNIST 3134 (-1‰) and Mo/Ce (0.002). Together with new, experimental data, we show that molybdenum isotopic fractionation is driven by preference of heavier Mo isotopes for a fluid phase over rutile, the dominant mineral host of Mo in eclogites. Moreover, the strongly perturbed δ98/95MoNIST 3134 and Mo/Ce of our samples requires that they experienced a large flux of oxidised fluid. This is consistent with channelised, reactive fluid flow through the subducted crust, following dehydration of the underlying, serpentinised slab mantle. The high δ98/95MoNIST 3134 of some arc lavas is the complement to this process.

CO3+1 network formation in ultra-high pressure carbonate liquids.

Carbonate liquids are an important class of molten salts, not just for industrial applications, but also in geological processes. Carbonates are generally expected to be simple liquids, in terms of ionic interactions between the molecular carbonate anions and metal cations, and therefore relatively structureless compared to more "polymerized" silicate melts. But there is increasing evidence from phase relations, metal solubility, glass spectroscopy and simulations to suggest the emergence of carbonate "networks" at length scales longer than the component molecular anions. The stability of these emergent structures are known to be sensitive to temperature, but are also predicted to be favoured by pressure. This is important as a recent study suggests that subducted surface carbonate may melt near the Earth's transition zone (~44 km), representing a barrier to the deep carbon cycle depending on the buoyancy and viscosity of these liquids. In this study we demonstrate a major advance in our understanding of carbonate liquids by combining simulations and high pressure measurements on a carbonate glass, (K2CO3-MgCO3) to pressures in excess of 40 GPa, far higher than any previous in situ study. We show the clear formation of extended low-dimensional carbonate networks of close CO32- pairs and the emergence of a "three plus one" local coordination environment, producing an unexpected increase in viscosity with pressure. Although carbonate melts may still be buoyant in the lower mantle, an increased viscosity by at least three orders of magnitude will restrict the upward mobility, possibly resulting in entrainment by the down-going slab.

Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities.

Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These 'soft tissues' have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil 'soft tissues' differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.

The chances of establishing a real-world Jurassic Park are slim. During the fossilization process, biological tissues degrade over millions of years, with some types of molecules breaking down faster than others. However, traces of biological material have been found inside some fossils. While some researchers believe these could be the remains of ancient proteins, blood vessels, and cells, traditionally thought to be among the least stable components of bone, others think that they have more recent sources. One hypothesis is that they are in fact biofilms formed by bacteria. To investigate the source of the biological material in fossil bone, Saitta et al. performed a range of analyses on the fossilized bones of a horned dinosaur called Centrosaurus. The bones were carefully excavated in a manner to reduce contamination, and the sediment the bones had been embedded in was also tested for comparison. Saitta et al. found no evidence of ancient dinosaur proteins. However, the fossils contained more organic carbon, DNA, and certain amino acids than the sediment surrounding them. Most of these appeared to have a very recent source. Sequencing the genetic material revealed that the fossil had become a habitat for an unusual community of microbes that is not found in the surrounding sediment or above ground. These buried microbes may have evolved unique ways to thrive inside fossils. Future work could investigate how these unusual organisms live and whether the communities vary in different parts of the world.

Nasal epithelial cells as surrogates for bronchial epithelial cells in airway inflammation studies.

The nose is an attractive source of airway epithelial cells, particularly in populations in which bronchoscopy may not be possible. However, substituting nasal cells for bronchial epithelial cells in the study of airway inflammation depends upon comparability of responses, and evidence for this is lacking. Our objective was to determine whether nasal epithelial cell inflammatory mediator release and receptor expression reflect those of bronchial epithelial cells. Paired cultures of undifferentiated nasal and bronchial epithelial cells were obtained from brushings from 35 subjects, including 5 children. Cells were subject to morphologic and immunocytochemical assessment. Mediator release from resting and cytokine-stimulated cell monolayers was determined, as was cell surface receptor expression. Nasal and bronchial cells had identical epithelial morphology and uniform expression of cytokeratin 19. There were no differences in constitutive expression of CD44, intercellular adhesion molecule-1, alphavbeta3, and alphavbeta5. Despite significantly higher constitutive release of IL-8, IL-6, RANTES (regulated on activation, normal T cell expressed and secreted), and matrix metalloproteinase (MMP)-9 from nasal compared with bronchial cells, the increments in release of all studied mediators in response to stimulation with IL-1beta and TNF-alpha were similar, and there were significant positive correlations between nasal and bronchial cell secretion of IL-6, RANTES, vascular endothelial growth factor, monocyte chemoattractant protein-1, MMP-9, and tissue inhibitor of metalloproteinase-1. Despite differences in absolute mediator levels, the responses of nasal and bronchial epithelial cells to cytokine stimulation were similar, expression of relevant surface receptors was comparable, and there were significant correlations between nasal and bronchial cell mediator release. Therefore, nasal epithelial cultures constitute an accessible surrogate for studying lower airway inflammation.

The impact of 12†months treatment with ivacaftor on Scottish paediatric patients with cystic fibrosis with the G551D mutation: a review.

We reviewed the impact of ivacaftor on Scottish paediatric patients with cystic fibrosis ≥6 years of age after 12 months of treatment. Statistically significant improvements in FEV1 and body mass index and a reduction in sweat chloride, all comparable with previously published data were observed. The findings also suggested reduced use of intravenous antibiotics and oral antibiotics. No significant adverse effects were observed but a possible association with cataract formation could not be excluded. This review suggests that, in the short term at least, ivacaftor is effective and safe in paediatric patients ≥6 years of age with G551D.

Experimental leaching of massive sulphide from TAG active hydrothermal mound and implications for seafloor mining.

Seafloor massive sulphide samples from the Trans-Atlantic Geotraverse active mound on the Mid-Atlantic Ridge were characterised and subjected to leaching experiments to emulate proposed mining processes. Over time, leached Fe is removed from solution by the precipitation of Fe oxy-hydroxides, whereas Cu and Pb leached remained in solution at ppb levels. Results suggest that bulk chemistry is not the main control on leachate concentrations; instead mineralogy and/or galvanic couples between minerals are the driving forces behind the type and concentration of metals that remain in solution. Dissolved concentrations exceed ANZECC toxicity guidelines by 620 times, implying the formation of localised toxicity in a stagnant water column. Moreover, concentrations will be higher when scaled to higher rock-fluid ratios and finer grain sizes proposed for mining scenarios. The distance at which dilution is achieved to meet guidelines is unlikely to be sufficient, indicating a need for the refinement of the mining process.

A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans.

The Ethiopian Rift Valley hosts the longest record of human co-existence with volcanoes on Earth, however, current understanding of the magnitude and timing of large explosive eruptions in this region is poor. Detailed records of volcanism are essential for interpreting the palaeoenvironments occupied by our hominin ancestors; and also for evaluating the volcanic hazards posed to the 10 million people currently living within this active rift zone. Here we use new geochronological evidence to suggest that a 200 km-long segment of rift experienced a major pulse of explosive volcanic activity between 320 and 170 ka. During this period, at least four distinct volcanic centres underwent large-volume (>10 km3) caldera-forming eruptions, and eruptive fluxes were elevated five times above the average eruption rate for the past 700 ka. We propose that such pulses of episodic silicic volcanism would have drastically remodelled landscapes and ecosystems occupied by early hominin populations.

An observational study of matrix metalloproteinase (MMP)-9 in cystic fibrosis.

BACKGROUND: In cystic fibrosis (CF), cross-sectional studies have reported sputum matrix metalloproteinase (MMP)-9 to be elevated and negatively correlated with FEV1. This longitudinal study examined the association between MMP-9 and tissue inhibitors of metalloproteinases (TIMPs) to prognostic parameters in CF. METHOD: A cross-sectional survey of CF and control subjects; CF patients were followed up for a median of 49 months. MMP-9 and TIMP-1 and TIMP-2 were quantified in sputum and plasma. RESULTS: Seventy-three patients with CF, median age 22 years, and 40 controls were recruited. Fifty-three of these CF patients were followed up. Prospectively, in CF subjects, plasma MMP-9 activity was adversely associated with FEV1 (ß -1.15 (95% CI -2.10, -0.20), p = 0.019) and rate of FEV1 decline, and plasma TIMP-1 was adversely associated with mortality: hazard ratio 3.66 (1.91-7.04), p < 0.001. CONCLUSIONS: These associations further justify investigation of MMP-9 and TIMP-1 as biomarkers for short- to medium-term FEV1 decline and mortality in patients with CF.