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Radiatively-cooled moist convection under idealised climate change scenarios: linear analysis
Get PDFIn order to explore the effects of climate change on atmospheric convection and the water cycle, we develop and analyse an extension of the Rainy-Bénard model, which is itself a moist version of the Rayleigh-Bénard model of dry convection. Including moisture changes the character of the convection, with condensation providing a source of buoyancy via latent heating and the system exhibiting moist conditional instability. A range of idealised climate change scenarios are constructed by appropriate choice of both the radiative cooling rate and the surface temperature, and these scenarios are investigated over a wide range of surface relative humidity values. We impose moist-pseudoadiabatic conditions at the top boundary, which allow the temperature and specific humidity values to vary at the top boundary in response to convection. The model is analysed across the different climate change scenarios space by examining diagnostics of the model's basic state, and its stability, with Convective Available Potential Energy (CAPE) calculations and a linear stability analysis. We use the linear stability results to identify new parameters relevant for this moist convective system, and to understand how the linear instability responds to the climate parameters. In particular, we define the “Rainy number” as a scaled ratio of positive-area CAPE and diffusion parameters. An alternative radiative-based Rainy number also is shown to describe the parameter space, especially for problems relating to changes in flux conditions. The Rainy number acts like the traditional Rayleigh number for dry Rayleigh-Bénard convection, and provides a novel theoretical tool for understanding how the dynamics and scales of moist convection and hence precipitation will change under climate change. The linear analysis predicts an intensification of the hydrological cycle under climate change. The model set up and linear analysis provide a basis for future investigation into the non-linear dynamics of (idealised) moist convection
Integrating mechanistic modelling with Bayesian optimisation: accelerated self-driving laboratories for RAFT polymerisation
Get PDFDiscovery of sustainable, high-performing materials on timescales to meet societal needs is only going to be achieved with the assistance of artificial intelligence and machine learning. Herein, a Bayesian optimisation algorithm is trained using in silico reactions facilitated by a new mechanistic model for reversible addition fragmentation chain transfer polymerisation (RAFT). This subsequently informs experimental multi-objective self-optimisation of RAFT polymerisation using an automated polymerisation platform capable of measuring the critical algorithm objectives (monomer conversion and molecular weight distribution) online. The platform autonomously identifies the Pareto-front representing the trade-off between monomer conversion and molar mass dispersity with a reduced number of reactions compared to the equivalent fully experimental optimisation process. This model-informed AI approach provides opportunities for much more sustainable and efficient discovery of polymeric materials and provides a benchmark for other complex chemical systems
Leptin and adiponectin in children and young persons with congenital adrenal hyperplasia
Get PDFObjectives
Patients with congenital adrenal hyperplasia (CAH) have increased prevalence of metabolic problems. We studied adiponectin, leptin and resistin in children with CAH, in relation to BMI, treatment, hormonal and metabolic biomarkers.
Design and Methods
We analysed 101 patients with 21-hydroxylase deficiency (54 females, 13.0 ± 2.92 years) from 13 centres in the United Kingdom, and 83 sex- and age-matched controls. Blood parameters (leptin, adiponectin, resistin, metabolic and hormonal markers) were measured in fasted state, between 09:00 and 11:00, after the first glucocorticoid (GC) dose.
Results
A difference in adipokines between patients and controls was only found for leptin in males (patients > control, P = .033). In patients and controls, leptin had a positive relationship with BMI-SDS (P < .001). However, adiponectin decreased with the BMI only in patients (P < .001). Contrary to published evidence on the effect of synthetic steroids on leptin, in our cohort, leptin decreased with the increasing first daily hydrocortisone (HC) dose (Log10Leptin = 4.1– 0.08xfirstGCdose (mg/m2), P = .009) but not with the total daily dose. When correcting for BMI, a positive relationship between leptin and insulin was only found in controls (P < .001). Adiponectin decreased with steroid precursor and androgen concentrations (17-hydroxyprogesterone, androstenedione, testosterone, 11-hydroxyandrostenedione, 11-ketotestosterone) in patients.
Conclusion
Our findings indicate a decrease in leptin with the HC dose, consistent with a detrimental effect of glucocorticoid on satiety and hunger pathways in CAH. Adiponectin was decreased in patients with increased androgens concentrations, suggesting it may be used as an indicator of metabolic risk associated with poor hormonal CAH control
Measurements of W+W− production cross-sections in pp collisions at √s = 13 TeV with the ATLAS detector
Get PDFA density functional theory study of thermally activated water splitting on the CuWO₄ (010) surface
Get PDFCuWO₄ shows promise as a suitable material for solar-driven water splitting to aid progress towards sustainable and carbon-free energy generation. In this work, we report a computational study of catalytic water splitting and hydrogen generation at CuWO₄ surfaces, employing calculations based on the density functional theory with on-site Coulomb and long-range dispersion corrections (DFT+U-D3). We have analyzed three potential thermodynamic and kinetic reaction profiles at the pristine CuWO₄ surface and one potential profile at the reduced CuWO₄ surface, examining the structural and electronic properties of the intermediates, as well as the transition states along the different pathways. Our findings reveal that along the pathway on the reduced surface, oxygen vacancies introduced in the surface led to under-coordinated Cu and W atoms and localized excess electrons, which significantly enhance the hydrogen evolution reaction
The sub‐μm petrography of the observed meteorite fall Winchcombe—A complex array of pristine and altered chondrite components
Get PDFSamples of observed meteorite falls provide important constraints on alteration histories of Solar System materials. Due to its rapid collection, terrestrial alteration in the observed Mighei-type (CM) carbonaceous chondrite fall Winchcombe was minimal. In this work, the petrography and mineralogy of three Winchcombe lamellae, two from the matrix and one from a lithological clast, were analyzed by transmission electron microscopy. Our results demonstrate that the matrix of Winchcombe is dominated by Mg-Fe-rich serpentine-type phyllosilicates and tochilinite-cronstedtite intergrowth (TCI)-like phases with variable, but generally high (petrologic type 2.0–2.3) alteration degrees that agree with petrologic types acquired on TCIs on larger scales in other work. However, we also located pristine areas in investigated lamellae such as homogeneous amorphous silicates and glassy particles with sulfide and metal inclusions that resemble altered cometary GEMS (glass with embedded metal and sulfides). One distinct GEMS-like domain shows Fe-rich metal and sulfide grains with oxygen-enriched rims in a Mg-rich amorphous groundmass embedded in organic matter, which likely shielded it from more severe alteration. Fe-Ni-sulfides are mainly pentlandite and concentrated in matrix lamellae. In addition to the sub-μm scale brecciated texture, the three lamellae show different alteration extents, further demonstrating the complex alteration nature of this CM2 meteorite
LRRC8A Regulates Outer Hair Cell Volume and Electromotility and is Required for Hearing
Get PDFDamage to the cochlear outer hair cell (OHC) is a major cause of deafness in mammals. OHCs amplify the auditory signals to enhance the sensitivity and sound frequency selectivity of the auditory system. However, detailed mechanisms underlying functional OHC regulation remain unclear. Here, it is demonstrated that volume-regulated anion channels (VRACs) are essential for OHC function. VRAC subunits are highly expressed in OHCs. Genetic deletion of leucin-rich repeat containing 8A (LRRC8A), the obligatory VRAC subunit, in hair cells results in hearing loss, whereas re-expressing LRRC8A in the cochlea restores hearing in LRRC8A-deficient mice. By employing patch-clamp electrophysiology, it is shown that VRAC in OHCs is activated by hypotonicity and is involved in regulating cell volume. Furthermore, the nonlinear capacitance (NLC), a measure of electromotility, is decreased in the OHCs from LRRC8A-deficient mice. Therefore, LRRC8A deficiency compromises electromotility of OHCs and impairs signal amplification. In conclusion, the findings highlight the essential role of VRAC in OHC electromotility and its necessity for auditory function
A Review on Perception of Binding Kinetics in Affinity Biosensors: Challenges and Opportunities
Get PDFThere are challenges associated with design and development of affinity biosensors due to the complicated multiphysics nature of the system. Understanding the binding interaction between target molecules and immobilized receptors and its kinetics is a crucial step to develop robust and reliable biosensor technologies. Evaluation of binding kinetics in biosensors becomes more important and challenging for clinical samples with a complex matrix. Despite drastic advancements in biosensor technologies, having a practical perception of the binding kinetics has remained a critical bottleneck due to limited fundamental understanding. This Review aims to provide a comprehensive discussion on concepts and advances developed so far for the perception of binding kinetics in affinity biosensors. Here, modeling approaches and measurement techniques are presented to characterize the binding interactions in biosensor technologies, while the effect of fouling and secondary factors in the binding interactions will be discussed in the concept of kinetics. This Review will investigate the existing research gaps and potential opportunities in the perception of binding kinetics and challenges to develop robust and reliable biosensors
Heterogeneous distribution of surface hydrothermal alteration in the Nevados de Chillán Fractured Geothermal System, Southern Andes
No full textThe spatial distribution of surface geothermal manifestations and hydrothermal alteration reflects the complex interplay of multiple factors controlling fluid circulation. This study aims to understand the different controls on the distribution of surface hydrothermal alteration, using the Nevados de Chillán Geothermal System (NChGS) as a case study. Lineament maps were created at 1:2500 and 1:5000 scales, and orientations of faults, fractures, and veins were measured. The pH measured ranges from 2.6 to 5.4. Surface temperature was measured and analyzed via Inverse Distance Weighted (IDW) interpolation in ArcGIS®. Surface hydrothermal alteration was mapped using drones, and minerals were identified through X-Ray Diffraction of whole rock and clay analysis, including chalcedony, opal, native sulfur, illite, kaolinite, iron oxides, sulfates, and hydrated sulfates. Illite crystallinity measured using the Full Width at Half Maximum index (FWHM) ranged from 0.05 to 1.77, while kaolinite crystallinity measuring using Aparicio-Galán-Ferrell index (AGFI), ranged from 0.73 to 1.15. The results show that the distribution of high temperatures (reaching 95 °C) and intense advanced argillic hydrothermal alteration is heterogeneous, controlled by lithological contact and the interaction between ∼E-W-trending lineaments associated with subvertical faults and NNW-striking surficial low-angle faults. Circulation of acid-sulfate waters rich in Fe, Al, and Cu occur primarily along fault/fracture networks, promoting the formation of high-crystallinity illite and kaolinite at the surface. This study proposes a link between surface geothermal manifestations with fault-fracture network and lithological controls within a fractured geothermal system in the Southern Andes
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