Vapour-phase crystallisation of silica from SiF4-bearing volcanic gases

Thermodynamic modelling of magmatic gases shows that SiF4 may be an important F-bearing species at the high pressures typical of magma reservoirs. Upon decompression during degassing, SiF4 will react with water vapour to form HF and silica. Common magmatic gases of high-T fumaroles seem to contain too little SiF4 to be a significant source of silica, except if extremely large amounts of gas percolate through a small volume of rock, as is the case in lava domes. Only if fluorine contents of the gases exceed 1 mol% detectable amounts of silica may be formed, but such high fluorine contents have not yet been observed in natural gases. Alternatively, silica may be formed by heating of cool SiF4-rich gases circulating in cooling lava bodies. We suggest that these mechanisms may be responsible for the deposition of crystalline silica, most probably cristobalite, observed in vesicles in lavas from Lewotolo volcano (Eastern Sunda Arc, Indonesia). Silica occurs as vapour-crystallised patches in vesicles, and is sometimes associated with F-phlogopite, which further supports F-rich conditions during deposition. Because of the connection between F-rich conditions and high-K volcanism, we propose that late-stage gaseous transport and deposition of silica may be more widespread in K-rich volcanoes than elsewhere, and long-term exposure to ash from eruptions of such volcanoes could therefore carry an increased risk for respiratory diseases. The dependence of SiF4/HF on temperature reported here differs from the current calibration used for temperature measurements of fumarolic gases by remote sensing techniques, and we suggest an updated calibration

An Experimental Study of Trace Element Fluxes from Subducted Oceanic Crust

We have determined experimentally the hydrous phase relations and trace element partitioning behaviour of ocean floor basalt protoliths at pressures and temperatures (3 GPa, 750-1000°C) relevant to melting in subduction zones. To avoid potential complexities associated with trace element doping of starting materials we have used natural, pristine mid-ocean ridge basalt (MORB from Kolbeinsey Ridge) and altered oceanic crust (AOC from Deep Sea Drilling Project leg 46, ∼20°N Atlantic). Approximately 15 wt % water was added to starting materials to simulate fluid fluxing from dehydrating serpentinite underlying the oceanic crust. The vapour-saturated solidus is sensitive to basalt K2O content, decreasing from 825 ± 25°C in MORB (∼0·04 wt % K2O) to ≈750°C in AOC (∼0·25 wt % K2O). Textural evidence indicates that near-solidus fluids are sub-critical in nature. The residual solid assemblage in both MORB and AOC experiments is dominated by garnet and clinopyroxene, with accessory kyanite, epidote, Fe-Ti oxide and rutile (plus quartz-coesite, phengite and apatite below the solidus). Trace element analyses of quenched silica-rich melts show a strong temperature dependence of key trace elements. In contrast to the trace element-doped starting materials of previous studies, we do not observe residual allanite. Instead, abundant residual epidote provides the host for thorium and light rare earth elements (LREE), preventing LREE from being released (ΣLREE 1500 and La/SmPUM (where PUM indicates primitive upper mantle) ∼1, most closely matching the geochemical signal of arc lavas worldwide, were generated from AOC at 800-850°

Acremonium phylogenetic overview and revision of Gliomastix, Sarocladium, and Trichothecium

AbstractOver 200 new sequences are generated for members of the genus Acremonium and related taxa including ribosomal small subunit sequences (SSU) for phylogenetic analysis and large subunit (LSU) sequences for phylogeny and DNA-based identification. Phylogenetic analysis reveals that within the Hypocreales, there are two major clusters containing multiple Acremonium species. One clade contains Acremonium sclerotigenum, the genus Emericellopsis, and the genus Geosmithia as prominent elements. The second clade contains the genera Gliomastix sensu stricto and Bionectria. In addition, there are numerous smaller clades plus two multi-species clades, one containing Acremonium strictum and the type species of the genus Sarocladium, and, as seen in the combined SSU/LSU analysis, one associated subclade containing Acremonium breve and related species plus Acremonium curvulum and related species. This sequence information allows the revision of three genera. Gliomastix is revived for five species, G. murorum, G. polychroma, G. tumulicola, G. roseogrisea, and G. masseei. Sarocladium is extended to include all members of the phylogenetically distinct A. strictum clade including the medically important A. kiliense and the protective maize endophyte A. zeae. Also included in Sarocladium are members of the phylogenetically delimited Acremonium bacillisporum clade, closely linked to the A. strictum clade. The genus Trichothecium is revised following the principles of unitary nomenclature based on the oldest valid anamorph or teleomorph name, and new combinations are made in Trichothecium for the tightly interrelated Acremonium crotocinigenum, Spicellum roseum, and teleomorph Leucosphaerina indica. Outside the Hypocreales, numerous Acremonium-like species fall into the Plectosphaerellaceae, and A. atrogriseum falls into the Cephalothecaceae

Trends in community response and long term outcomes from paediatric cardiac arrest:A retrospective observational study

AIM: This study aimed to investigate trends over time in pre-hospital factors for pediatric out-of-hospital cardiac arrest (pOHCA) and long-term neurological and neuropsychological outcomes. These have not been described before in large populations.METHODS: Non-traumatic arrest patients, 1 day-17 years old, presented to the Sophia Children's Hospital from January 2002 to December 2020, were eligible for inclusion. Favorable neurological outcome was defined as Pediatric Cerebral Performance Categories (PCPC) 1-2 or no difference with pre-arrest baseline. The trend over time was tested with multivariable logistic and linear regression models with year of event as independent variable.FINDINGS: Over a nineteen-year study period, the annual rate of long-term favorable neurological outcome, assessed at a median 2·5 years follow-up, increased significantly (OR 1·10, 95%-CI 1·03-1·19), adjusted for confounders. Concurrently, annual automated external defibrillator (AED) use and, among adolescents, initial shockable rhythm increased significantly (OR 1·21, 95% CI 1·10-1·33 and OR 1·15, 95% CI 1·02-1·29, respectively), adjusted for confounders. For generalizability purposes, only the total intelligence quotient (IQ) was considered for trend analysis of all tested domains. Total IQ scores and bystander basic life support (BLS) rate did not change significantly over time.INTERPRETATION: Long-term favorable neurological outcome, assessed at a median 2·5 years follow-up, improved significantly over the study period. Total IQ scores did not significantly change over time. Furthermore, AED use (OR 1·21, 95%CI 1.10-1·33) and shockable rhythms among adolescents (OR1·15, 95%CI 1·02-1·29) increased over time.</p

Efficacy of a loading dose of IV salbutamol in children with severe acute asthma admitted to a PICU:a randomized controlled trial

The optimal dose regimen for intravenous (IV) treatment in children with severe acute asthma (SAA) is still a matter of debate. We assessed the efficacy of adding a salbutamol loading dose to continuous infusion with salbutamol in children admitted to a pediatric intensive care unit (PICU) with SAA. This multicentre, placebo-controlled randomized trial in the PICUs of four tertiary care children’s hospitals included children (2–18 years) with SAA admitted between 2017 and 2019. Children were randomized to receive either a loading dose IV salbutamol (15 mcg/kg, max. 750 mcg) or normal saline while on continuous salbutamol infusion. The primary outcome was the asthma score (Qureshi) 1 h after the intervention. Analysis of covariance models was used to evaluate sensitivity to change in asthma scores. Serum concentrations of salbutamol were obtained. Fifty-eight children were included (29 in the intervention group). Median baseline asthma score was 12 (IQR 10–13) in the intervention group and 11 (9–12) in the control group (p = 0.032). The asthma score 1 h after the intervention did not differ significantly between the groups (p = 0.508, β-coefficient = 0.283). The median increase in salbutamol plasma levels 10 min after the intervention was 13 μg/L (IQR 5–24) in the intervention group and 4 μg/L (IQR 0–7) in the control group (p = 0.001). Side effects were comparable between both groups. Conclusion: We found no clinical benefit of adding a loading dose IV salbutamol to continuous infusion of salbutamol, in children admitted to the PICU with SAA. Clinically significant side effects from the loading dose were not encountered.What is Known:• Pediatric asthma guidelines struggle with an evidence-based approach for the treatment of SAA beyond the initial steps of oxygen suppletion, repetitive administration of inhaled β2-agonists, and systemic steroids.• During an SAA episode, effective delivery of inhaled drugs is unpredictable due to severe airway obstruction.What is New:• This study found no beneficial effect of an additional loading dose IV salbutamol in children admitted to the PICU.• This study found no clinically significant side effects from the loading dose

Daily interruption of sedation in critically ill children:study protocol for a randomized controlled trial

BACKGROUND: In adult patients who are critically ill and mechanically ventilated, daily interruption of sedation (DSI) is an effective method of improving sedation management, resulting in a decrease of the duration of mechanical ventilation, the length of stay in the intensive care unit (ICU) and the length of stay in the hospital. It is a safe and effective approach and is common practice in adult ICUs. For critically ill children it is unknown if DSI is effective and feasible. The aim of this multicenter randomized controlled trial is to evaluate the safety and efficacy of daily sedation interruption in critically ill children. METHODS/DESIGN: Children between 0 and 18 years of age who require mechanical ventilation, with an expected duration of at least 48 h and need for sedative infusion, will be included. After enrollment patients will be randomly assigned to DSI in combination with protocolized sedation (intervention group) or protocolized continuous sedation (control group). A sedation protocol that contains an algorithm for increasing and weaning of sedatives and analgesics will be used. The sedative infusion will be restarted if the patient becomes uncomfortable or agitated according to the sedation protocol. The primary endpoint is the number of ventilator-free days at 28 days. TRIAL REGISTRATION: NTR203

Toward a Novel Multilocus Phylogenetic Taxonomy for the Dermatophytes.

Type and reference strains of members of the onygenalean family Arthrodermataceae have been sequenced for rDNA ITS and partial LSU, the ribosomal 60S protein, and fragments of β-tubulin and translation elongation factor 3. The resulting phylogenetic trees showed a large degree of correspondence, and topologies matched those of earlier published phylogenies demonstrating that the phylogenetic representation of dermatophytes and dermatophyte-like fungi has reached an acceptable level of stability. All trees showed Trichophyton to be polyphyletic. In the present paper, Trichophyton is restricted to mainly the derived clade, resulting in classification of nearly all anthropophilic dermatophytes in Trichophyton and Epidermophyton, along with some zoophilic species that regularly infect humans. Microsporum is restricted to some species around M. canis, while the geophilic species and zoophilic species that are more remote from the human sphere are divided over Arthroderma, Lophophyton and Nannizzia. A new genus Guarromyces is proposed for Keratinomyces ceretanicus. Thirteen new combinations are proposed; in an overview of all described species it is noted that the largest number of novelties was introduced during the decades 1920-1940, when morphological characters were used in addition to clinical features. Species are neo- or epi-typified where necessary, which was the case in Arthroderma curreyi, Epidermophyton floccosum, Lophophyton gallinae, Trichophyton equinum, T. mentagrophytes, T. quinckeanum, T. schoenleinii, T. soudanense, and T. verrucosum. In the newly proposed taxonomy, Trichophyton contains 16 species, Epidermophyton one species, Nannizzia 9 species, Microsporum 3 species, Lophophyton 1 species, Arthroderma 21 species and Ctenomyces 1 species, but more detailed studies remain needed to establish species borderlines. Each species now has a single valid name. Two new genera are introduced: Guarromyces and Paraphyton. The number of genera has increased, but species that are relevant to routine diagnostics now belong to smaller groups, which enhances their identification

Paediatric Acute Respiratory Distress Syndrome Neuromuscular Blockade study (PAN-study):a phase IV randomised controlled trial of early neuromuscular blockade in moderate-to-severe paediatric acute respiratory distress syndrome

BACKGROUND: Paediatric acute respiratory distress syndrome (PARDS) is a manifestation of severe, life-threatening lung injury necessitating mechanical ventilation with mortality rates ranging up to 40–50%. Neuromuscular blockade agents (NMBAs) may be considered to prevent patient self-inflicted lung injury in PARDS patients, but two trials in adults with severe ARDS yielded conflicting results. To date, randomised controlled trials (RCT) examining the effectiveness and efficacy of NMBAs for PARDS are lacking. We hypothesise that using NMBAs for 48 h in paediatric patients younger than 5 years of age with early moderate-to-severe PARDS will lead to at least a 20% reduction in cumulative respiratory morbidity score 12 months after discharge from the paediatric intensive care unit (PICU). METHODS: This is a phase IV, multicentre, randomised, double-blind, placebo-controlled trial performed in level-3 PICUs in the Netherlands. Eligible for inclusion are children younger than 5 years of age requiring invasive mechanical ventilation with positive end-expiratory pressure (PEEP) ≥ 5 cm H(2)O for moderate-to-severe PARDS occurring within the first 96 h of PICU admission. Patients are randomised to continuous infusion of rocuronium bromide or placebo for 48 h. The primary endpoint is the cumulative respiratory morbidity score 12 months after PICU discharge, adjusted for confounding by age, gestational age, family history of asthma and/or allergy, season in which questionnaire was filled out, day-care and parental smoking. Secondary outcomes include respiratory mechanics, oxygenation and ventilation metrics, pulmonary and systemic inflammation markers, prevalence of critical illness polyneuropathy and myopathy and metrics for patient outcome including ventilator free days at day 28, length of PICU and hospital stay, and mortality DISCUSSION: This is the first paediatric trial evaluating the effects of muscular paralysis in moderate-to-severe PARDS. The proposed study addresses a huge research gap identified by the Paediatric Acute Lung Injury Consensus Collaborative by evaluating practical needs regarding the treatment of PARDS. Paediatric critical care practitioners are inclined to use interventions such as NMBAs in the most critically ill. This liberal use must be weighed against potential side effects. The proposed study will provide much needed scientific support in the decision-making to start NMBAs in moderate-to-severe PARDS. TRIAL REGISTRATION: ClinicalTrials.govNCT02902055. Registered on September 15, 2016

Candida albicans repetitive elements display epigenetic diversity and plasticity

Transcriptionally silent heterochromatin is associated with repetitive DNA. It is poorly understood whether and how heterochromatin differs between different organisms and whether its structure can be remodelled in response to environmental signals. Here, we address this question by analysing the chromatin state associated with DNA repeats in the human fungal pathogen Candida albicans. Our analyses indicate that, contrary to model systems, each type of repetitive element is assembled into a distinct chromatin state. Classical Sir2-dependent hypoacetylated and hypomethylated chromatin is associated with the rDNA locus while telomeric regions are assembled into a weak heterochromatin that is only mildly hypoacetylated and hypomethylated. Major Repeat Sequences, a class of tandem repeats, are assembled into an intermediate chromatin state bearing features of both euchromatin and heterochromatin. Marker gene silencing assays and genome-wide RNA sequencing reveals that C. albicans heterochromatin represses expression of repeat-associated coding and non-coding RNAs. We find that telomeric heterochromatin is dynamic and remodelled upon an environmental change. Weak heterochromatin is associated with telomeres at 30?°C, while robust heterochromatin is assembled over these regions at 39?°C, a temperature mimicking moderate fever in the host. Thus in C. albicans, differential chromatin states controls gene expression and epigenetic plasticity is linked to adaptation

Multi-stage subduction-related metasomatism recorded in whiteschists from the Dora-Maira Massif, Western Alps

Whiteschists from the Dora-Maira massif (Western Alps, Italy) are Mg and K-rich metasomatised granites which experienced ultra-high pressure metamorphism and fluid-rock interaction during Alpine continental subduction. The sources and timing of fluid infiltration are a source of significant debate. In this study we present boron (B) isotopes and other fluid-mobile trace element (FME) concentrations in various generations of phengite from whiteschists and their country rock protoliths to investigate the sources and timing of metasomatic fluid influx. Reconstructed bulk rock concentrations based on modal data and mineral compositions indicate that significant amounts B and other FME were added to the rock during prograde metamorphism, but that this fluid influx postdates the main Mg metasomatic event. High B concentrations (150–350 µg/g) and light δ11B values (-16 to -4 ‰) recorded in phengite point to a B-rich sediment-derived fluid as the main source of B in the whiteschists. Further redistribution of FME during metamorphism was associated with breakdown of hydrous minerals such as talc, phlogopite and ellenbergerite. The source of the Mg-rich fluids cannot be constrained based on the B data in phengite, since its signature was overprinted by the later main B metasomatic event. Rare tourmaline-bearing whiteschists record additional information about B processes. Tourmaline δ11B values (-6 to +1 ‰) are in isotopic equilibrium with similar fluids to those recorded in most phengite, but phengites in tourmaline-bearing samples records anomalous B isotope compositions that reflect later redistribution of B. This study demonstrates the utility of in situ analyses in unravelling complex fluid-rock interaction histories, where whole rock analyses make it difficult to distinguish between different stages of fluid-rock interaction. Polymetasomatism may result in decoupling of different isotopic systems, thus complicating their interpretation. The Dora-Maira whiteschists interacted with multiple generations of fluids during subduction and therefore may represent a long-lived fluid pathway