Self-powered, flexible and room temperature operated solution processed hybrid metal halide p-type sensing element for efficient hydrogen detection

Hydrogen (H2) is a well-known reduction gas and for safety reasons is very important to be detected. The most common systems employed along its detection are metal oxide-based elements. However, the latter demand complex and expensive manufacturing techniques, while they also need high temperatures or UV light to operate effectively. In this work, we first report a solution processed hybrid mixed halide spin coated perovskite films that have been successfully applied as portable, flexible, self-powered, fast and sensitive hydrogen sensing elements, operating at room temperature. The minimum concentrations of H2 gas that could be detected was down to 10 ppm. This work provides a new pathway on gases interaction with perovskite materials, launches new questions that must be addressed regarding the sensing mechanisms involved due to the utilization of halide perovskite sensing elements while also demonstrates the potential that these materials have on beyond solar cell applications

Isolation of Oct4-Expressing Extraembryonic Endoderm Precursor Cell Lines

BACKGROUND:The extraembryonic endoderm (ExEn) defines the yolk sac, a set of membranes that provide essential support for mammalian embryos. Recent findings suggest that the committed ExEn precursor is present already in the embryonic Inner Cell Mass (ICM) as a group of cells that intermingles with the closely related epiblast precursor. All ICM cells contain Oct4, a key transcription factor that is first expressed at the morula stage. In vitro, the epiblast precursor is most closely represented by the well-characterized embryonic stem (ES) cell lines that maintain the expression of Oct4, but analogous ExEn precursor cell lines are not known and it is unclear if they would express Oct4. METHODOLOGY/PRINCIPAL FINDINGS:Here we report the isolation and characterization of permanently proliferating Oct4-expressing rat cell lines ("XEN-P cell lines"), which closely resemble the ExEn precursor. We isolated the XEN-P cell lines from blastocysts and characterized them by plating and gene expression assays as well as by injection into embryos. Like ES cells, the XEN-P cells express Oct4 and SSEA1 at high levels and their growth is stimulated by leukemia inhibitory factor, but instead of the epiblast determinant Nanog, they express the ExEn determinants Gata6 and Gata4. Further, they lack markers characteristic of the more differentiated primitive/visceral and parietal ExEn stages, but exclusively differentiate into these stages in vitro and contribute to them in vivo. CONCLUSIONS/SIGNIFICANCE:Our findings (i) suggest strongly that the ExEn precursor is a self-renewable entity, (ii) indicate that active Oct4 gene expression (transcription plus translation) is part of its molecular identity, and (iii) provide an in vitro model of early ExEn differentiation

Spike-Based Bayesian-Hebbian Learning of Temporal Sequences

Many cognitive and motor functions are enabled by the temporal representation and processing of stimuli, but it remains an open issue how neocortical microcircuits can reliably encode and replay such sequences of information. To better understand this, a modular attractor memory network is proposed in which meta-stable sequential attractor transitions are learned through changes to synaptic weights and intrinsic excitabilities via the spike-based Bayesian Confidence Propagation Neural Network (BCPNN) learning rule. We find that the formation of distributed memories, embodied by increased periods of firing in pools of excitatory neurons, together with asymmetrical associations between these distinct network states, can be acquired through plasticity. The model's feasibility is demonstrated using simulations of adaptive exponential integrate-and-fire model neurons (AdEx). We show that the learning and speed of sequence replay depends on a confluence of biophysically relevant parameters including stimulus duration, level of background noise, ratio of synaptic currents, and strengths of short-term depression and adaptation. Moreover, sequence elements are shown to flexibly participate multiple times in the sequence, suggesting that spiking attractor networks of this type can support an efficient combinatorial code. The model provides a principled approach towards understanding how multiple interacting plasticity mechanisms can coordinate hetero-associative learning in unison

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

A novel magnetic HS−-adsorptive nanocomposite photocatalyst (rGO/CoMn2O4-MgFe2O4) for hydrogen fuel production using H2S feed

Synthesis of low-cost, eco-friendly, semiconducting solar-energy materials with excellent photocatalytic activity [high surface area, good reactant adsorption, photon harnessing in the visible region, and low charge recombination] for application in pollutant conversion to hydrogen is of great importance from environmental remediation as well as green energy and fuel production perspectives. In the present work, a magnetic heterojunction of CoMn2O4/MgFe2O4 and reduced graphene oxide (rGO) was synthesized through a combined Hummers’/hydrothermal method. The obtained nanocomposite (rGO/CoMn2O4-MgFe2O4) was employed for photocatalytic conversion of H2S feed into hydrogen fuel. Adsorption studies in the feed solution proved a good capability for the photocatalyst to adsorb HS− reactant from the reaction medium. This effect was ascribed to the presence of the CoMn2O4 component, serving as a strong bisulfide adsorbent. VSM (vibrating sample magnetometry) analysis revealed that the magnetic property of the photocatalyst was due to the MgFe2O4 component. Photocatalytic investigations showed that the addition of rGO to the CoMn2O4/MgFe2O4 nanocomposite not only improves its reactant adsorption capacity, but also increases the photocatalyst surface area, enhances photon absorption, and suppresses the charge (e/h) recombination, which eventually boosts the photocatalyst activity to produce more hydrogen fuel (∼1.5 times)

Hydrothermal synthesis of ZnO–doped ceria nanorods: Effect of zno content on the redox properties and the co oxidation performance

The rational design of highly efficient, noble metal–free metal oxides is one of the main research priorities in the area of catalysis. To this end, the fine tuning of ceria–based mixed oxides by means of aliovalent metal doping has currently received particular attention due to the peculiar metal–ceria synergistic interactions. Herein, we report on the synthesis, characterization and catalytic evaluation of ZnO–doped ceria nanorods (NR). In particular, a series of bare CeO2 and ZnO oxides along with CeO2/ZnO mixed oxides of different Zn/Ce atomic ratios (0.2, 0.4, 0.6) were prepared by the hydrothermal method. All prepared samples were characterized by X–ray diffraction (XRD), N2 physisorption, temperature–programmed reduction (TPR), scanning electron microscopy with energy dispersive X–ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The CO oxidation reaction was employed as a probe reaction to gain insight into structure–property relationships. The results clearly showed the superiority of mixed oxides as compared to bare ones, which could be ascribed to a synergistic ZnO–CeO2 interaction towards an improved reducibility and oxygen mobility. A close correlation between the catalytic activity and oxygen storage capacity (OSC) was disclosed. Comparison with relevant literature studies verifies the role of OSC as a key activity descriptor for reactions following a redox–type mechanism. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

A life cycle assessment of PCM and VIP in warm Mediterranean climates and their introduction as a strategy to promote energy savings and mitigate carbon emissions

The building stock in southern Europe grossly lacks sufficient thermal envelope insulation, leading to high energy inputs and corresponding CO2 emissions. Phase change materials (PCMs) and vacuum insulations panels (VIPs) could be an innovative way to curtail the high heating and cooling energy inputs to maintain comfort; however, their efficiency and environmental performance in the southern Mediterranean climate is largely unknown. To this end, two demo houses, 27 m3 each, were constructed in the island of Crete, southern Greece. The first was constructed using conventional building materials, while in the second PCMs and VIPs were used, as a research test-bed. Actual life cycle inventory (LCI) data were collected and the life cycle assessment (LCA) methodology was employed to estimate the environmental impacts attributed both to their construction and operational phase. Compared to the conventional demo house the one covered with PCMs and VIPs appear to have a 34% higher total environmental footprint, which is attributed to the production process of PCMs and VIPs. Nonetheless, the energy savings observed during the operational phase, attributed to their higher thermal insulation, can compensate the higher environmental footprint of the construction phase within a year, depending on PCM's enthalpy. Specifically, it was identified that PCMs and VIPs largely reduced daily indoor temperature fluctuations, improving indoor thermal comfort and leading to energy savings. As such, even though their installation is associated with an initial higher environmental footprint, large energy savings, compared to conventional demo house, are achieved during its operational phase. This suggests that the introduction of PCMs and VIPs could be an efficient and environmentally friendly route to enhance energy savings and reduce the environmental footprint of building stock. © 2019 AIMS Press

Highly sensitive and selective NO2 chemical sensors based on Al doped NiO thin films

Al-doped Nickel oxide (Al:NiO) nanostructured thin films, prepared by RF sputtering technique, were tested for NO2 gas detection. The films were deposited on alumina substrates with thicknesses ranging between 52 nm and 167 nm, while the at.% of Al was varied from 5.0% to 6.7%. The effect of the thickness on the morphological, structural and optical properties was investigated. Moreover, the sensing characteristics were examined and optimized with respect to film thickness and operating temperature (200 °C and 300 °C), at NO2 concentrations ranging from 200 ppb to 2500 ppb and in presence of a constant relative humidity (RH) of 40%. An ultimate response of 271% towards a NO2 concentration of 200 ppb at 200 °C was obtained, concluding that Al:NiO can be potentially used as a sensing material for this specific gas