Observation of centimetre-scale argon diffusion in alkali feldspars: implications for ⁴⁰Ar/³⁹Ar thermochronology

New data from a gem-quality feldspar from Itrongay, Madagascar, record naturally occurring 40Ar/39Ar age profiles which can be numerically modelled by invoking a single diffusion mechanism and show that microtexturally simple crystals are capable of recording complex thermal histories. We present the longest directly measured, naturally produced 40Ar*-closure profiles from a single, homogeneous orthoclase feldspar. These data appear to confirm the assumption that laboratory derived diffusion parameters are valid in nature and over geological timescales. Diffusion domains are defined by crystal faces and ancient cracks, thus in gem-quality feldspars the diffusion domain size equates to the physical grain size. The data also illustrate the potential of large, gem-quality feldspars to record detailed thermal histories over tens of millions of years and such samples should be considered for future studies on the slow cooling of continental crust

Inherent tracers for carbon capture and storage in sedimentary formations: composition and applications

Inherent tracers - the “natural” isotopic and trace gas composition of captured CO₂ streams – are potentially powerful tracers for use in CCS technology. This review outlines for the first time the expected carbon isotope and noble gas compositions of captured CO₂ streams from a range of feedstocks, CO₂-generating processes and carbon capture techniques. The C-isotope composition of captured CO₂ will be most strongly controlled by the feedstock, but significant isotope fractionation is possible during capture; noble gas concentrations will be controlled by the capture technique employed. Comparison with likely baseline data suggests that CO₂ generated from fossil fuel feedstocks will often have δ13C distinguishable from storage reservoir CO₂. Noble gases in amine-captured CO₂ streams are likely to be low concentration, with isotopic ratios dependant on the feedstock, but CO₂ captured from oxyfuel plants may be strongly enriched in Kr and Xe which are potentially valuable subsurface tracers. CO₂ streams derived from fossil fuels will have noble gas isotope ratios reflecting a radiogenic component that will be difficult to distinguish in the storage reservoir, but inheritance of radiogenic components will provide an easily recognisable signature in the case of any unplanned migration into shallow aquifers or to the surface

Targeting the Complement Serine Protease MASP-2 as a Therapeutic Strategy for Coronavirus Infections

MASP-2, mannose-binding protein-associated serine protease 2, is a key enzyme in the lectin pathway of complement activation. Hyperactivation of this protein by human coronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2 has been found to contribute to aberrant complement activation in patients, leading to aggravated lung injury with potentially fatal consequences. This hyperactivation is triggered in the lungs through a conserved, direct interaction between MASP-2 and coronavirus nucleocapsid (N) proteins. Blocking this interaction with monoclonal antibodies and interfering directly with the catalytic activity of MASP-2, have been found to alleviate coronavirus-induced lung injury both in vitro and in vivo. In this study, a virtual library of 8736 licensed drugs and clinical agents has been screened in silico according to two parallel strategies. The first strategy aims at identifying direct inhibitors of MASP-2 catalytic activity, while the second strategy focusses on finding protein-protein interaction inhibitors (PPIs) of MASP-2 and coronaviral N proteins. Such agents could represent promising support treatment options to prevent lung injury and reduce mortality rates of infections caused by both present and future-emerging coronaviruses. Forty-six drug repurposing candidates were purchased and, for the ones selected as potential direct inhibitors of MASP-2, a preliminary in vitro assay was conducted to assess their interference with the lectin pathway of complement activation. Some of the tested agents displayed a dose-response inhibitory activity of the lectin pathway, potentially providing the basis for a viable support strategy to prevent the severe complications of coronavirus infections

Singing teaching as a therapy for chronic respiratory disease - a randomised controlled trial and qualitative evaluation

<p>Abstract</p> <p>Background</p> <p>Despite optimal pharmacological therapy and pulmonary rehabilitation, patients with COPD continue to be breathless. There is a need to develop additional strategies to alleviate symptoms. Learning to sing requires control of breathing and posture and might have benefits that translate into daily life.</p> <p>Methods</p> <p>To test this hypothesis we performed a randomised controlled trial, comparing a six week course of twice weekly singing classes to usual care, in 28 COPD patients. The experience of singing was assessed in a qualitative fashion, through interviews with a psychologist. In addition, we surveyed patients with chronic respiratory conditions who participated in a series of open singing workshops.</p> <p>Results</p> <p>In the RCT, the physical component score of the SF36 improved in the singers (n = 15) compared to the controls (n = 13); +7.5(14.6) vs. -3.8(8.4) p = 0.02. Singers also had a significant fall in HAD anxiety score; -1.1(2.7) vs. +0.8(1.7) p = 0.03. Singing did not improve single breath counting, breath hold time or shuttle walk distance. In the qualitative element, 8 patients from the singing group were interviewed. Positive effects on physical sensation, general well-being, community/social support and achievement/efficacy emerged as common themes. 150 participants in open workshops completed a questionnaire. 96% rated the workshops as "very enjoyable" and 98% thought the workshop had taught them something about breathing in a different way. 81% of attendees felt a "marked physical difference" after the workshop.</p> <p>Conclusion</p> <p>Singing classes can improve quality of life measures and anxiety and are viewed as a very positive experience by patients with respiratory disease; no adverse consequences of participation were observed.</p> <p>Trial Registration</p> <p>Current Controlled Trials - ISRCTN17544114.</p

Stability of insulating phase in the chiral Kondo lattice model

In this work, the stability of the insulating phase of the 1D chiral Kondo lattice model is studied at half-filling, within the framework of self-consistent variational theory. It is found that arbitrarily small interaction would drive the system from a conducting phase to an insulating phase, in spite of the chirality of the conducting band.Comment: 10 pages, IPT-EPFL preprint, submitted to PRB as a brief report for publicatio

Representations of the occupation number matrix on the LDA/GGA+U method

An analysis of the general represntation of the occupation number matrix on density functional theory in conjunction with the generalized Hubbard model is presented. A central fact that will be addressed is that the total charge density cannot be broken down into simple atomic contributions. This fact means that the orbital occupations are not well defined. Different representations of the occupation number matrix, both that it conserves and that it does not conserve the number of electrons of the system, are compared. A localized basis set is used, which is suitable for large-scale electronic structure calculations based on the density functional theory. This methodology is applied to typical and well-analysed transition-metal oxide bulk systems and to Cr-doped zinc chalogenides and chalcopyrites. The bandgap, magnetic moment and detailed electronic structures are investigated and discussed with the different choices of the occupation number matrix. The results are in good agreement with previous theoretical and experimental studies

The Inherent Tracer Fingerprint of Captured CO2.

Carbon capture and storage (CCS) is the only currently available technology that can directly reduce anthropogenic CO2 emissions arising from fossil fuel combustion. Monitoring and verification of CO2 stored in geological reservoirs will be a regulatory requirement and so the development of reliable monitoring techniques is essential. The isotopic and trace gas composition - the inherent fingerprint - of captured CO2 streams is a potentially powerful, low cost geochemical technique for tracking the fate of injected gas in CCS projects; carbon and oxygen isotopes, in particular, have been used as geochemical tracers in a number of pilot CO2 storage sites, and noble gases are known to be powerful tracers of natural CO2 migration. However, the inherent tracer fingerprint in captured CO2 streams has yet to be robustly investigated and documented and key questions remain, including how consistent is the fingerprint, what controls it, and will it be retained en route to and within the storage reservoir? Here we present the first systematic measurements of the carbon and oxygen isotopes and the trace noble gas composition of anthropogenic CO2 captured from combustion power stations and fertiliser plants. The analysed CO2 is derived from coal, biomass and natural gas feedstocks, using amine capture, oxyfuel and gasification processes, from six different CO2 capture plants spanning four different countries. We find that δ13C values are primarily controlled by the δ13C of the feedstock while δ18O values are predominantly similar to atmospheric O2. Noble gases are of low concentration and exhibit relative element abundances different to expected reservoir baselines and air, with isotopic compositions that are similar to air or fractionated air. The use of inherent tracers for monitoring and verification was provisionally assessed by analysing CO2 samples produced from two field storage sites after CO2 injection. These experiments at Otway, Australia, and Aquistore, Canada, highlight the need for reliable baseline data. Noble gas data indicates noble gas stripping of the formation water and entrainment of Kr and Xe from an earlier injection experiment at Otway, and inheritance of a distinctive crustal radiogenic noble gas fingerprint at Aquistore. This fingerprint can be used to identify unplanned migration of the CO2 to the shallow subsurface or surface

Noble gases confirm plume related mantle degassing beneath Southern Africa

Southern Africa is characterised by unusually elevated topography and abnormal heat flow. This can be explained by thermal perturbation of the mantle, but the origin of this is unclear. Geophysics has not detected a thermal anomaly in the upper mantle and there is no geochemical evidence of an asthenosphere mantle contribution to the Cenozoic volcanic record of the region. Here we show that natural CO2 seeps along the Ntlakwe-Bongwan fault within KwaZulu-Natal, South Africa, have C-He isotope systematics that support an origin from degassing mantle melts. Neon isotopes indicate that the melts originate from a deep mantle source that is similar to the mantle plume beneath Réunion, rather than the convecting upper mantle or sub-continental lithosphere. This confirms the existence of the Quathlamba mantle plume and importantly provides the first evidence in support of upwelling deep mantle beneath Southern Africa, helping to explain the regions elevation and abnormal heat flow

Age and context of the oldest known hominin fossils from Flores

Recent excavations at the early Middle Pleistocene site of Mata Menge in the So\u27a Basin of central Flores, Indonesia, have yielded hominin fossils1 attributed to a population ancestral to Late Pleistocene Homo floresiensis2. Here we describe the age and context of the Mata Menge hominin specimens and associated archaeological findings. The fluvial sandstone layer from which the in situ fossils were excavated in 2014 was deposited in a small valley stream around 700 thousand years ago, as indicated by 40Ar/39Ar and fission track dates on stratigraphically bracketing volcanic ash and pyroclastic density current deposits, in combination with coupled uranium-series and electron spin resonance dating of fossil teeth. Palaeoenvironmental data indicate a relatively dry climate in the So\u27a Basin during the early Middle Pleistocene, while various lines of evidence suggest the hominins inhabited a savannah-like open grassland habitat with a wetland component. The hominin fossils occur alongside the remains of an insular fauna and a simple stone technology that is markedly similar to that associated with Late Pleistocene H. floresiensis