Hybrid chitosan derivative-carbon suport for oxygen reduction reactions

New hybrid chitosan derivative-carbon black was prepared and used as support for Pt nanoparticles. These catalysts improved the activity toward oxygen reduction reaction (ORR), compared with those of commercial Pt/C catalyst. The biopolymer chitosan provided an efficient and sustainable surface nitrogen source associated with the superior performance of the catalysts.Peer reviewe

Effects of intubation timing in patients with COVID-19 throughout the four waves of the pandemic : a matched analysis

The primary aim of our study was to investigate the association between intubation timing and hospital mortality in critically ill patients with COVID-19-associated respiratory failure. We also analysed both the impact of such timing throughout the first four pandemic waves and the influence of prior non-invasive respiratory support on outcomes. This is a secondary analysis of a multicentre, observational and prospective cohort study that included all consecutive patients undergoing invasive mechanical ventilation due to COVID-19 from across 58 Spanish intensive care units (ICU) participating in the CIBERESUCICOVID project. The study period was between 29 February 2020 and 31 August 2021. Early intubation was defined as that occurring within the first 24 h of intensive care unit (ICU) admission. Propensity score (PS) matching was used to achieve balance across baseline variables between the early intubation cohort and those patients who were intubated after the first 24 h of ICU admission. Differences in outcomes between early and delayed intubation were also assessed. We performed sensitivity analyses to consider a different timepoint (48 h from ICU admission) for early and delayed intubation. Of the 2725 patients who received invasive mechanical ventilation, a total of 614 matched patients were included in the analysis (307 for each group). In the unmatched population, there were no differences in mortality between the early and delayed groups. After PS matching, patients with delayed intubation presented higher hospital mortality (27.3% versus 37.1%, p =0.01), ICU mortality (25.7% versus 36.1%, p=0.007) and 90-day mortality (30.9% versus 40.2%, p=0.02) when compared to the early intubation group. Very similar findings were observed when we used a 48-hour timepoint for early or delayed intubation. The use of early intubation decreased after the first wave of the pandemic (72%, 49%, 46% and 45% in the first, second, third and fourth wave, respectively; first versus second, third and fourth waves p<0.001). In both the main and sensitivity analyses, hospital mortality was lower in patients receiving high-flow nasal cannula (n=294) who were intubated earlier. The subgroup of patients undergoing NIV (n=214) before intubation showed higher mortality when delayed intubation was set as that occurring after 48 h from ICU admission, but not when after 24 h. In patients with COVID-19 requiring invasive mechanical ventilation, delayed intubation was associated with a higher risk of hospital mortality. The use of early intubation significantly decreased throughout the course of the pandemic. Benefits of such an approach occurred more notably in patients who had received high-flow nasal cannul

Prognostic implications of comorbidity patterns in critically ill COVID-19 patients: A multicenter, observational study

Background The clinical heterogeneity of COVID-19 suggests the existence of different phenotypes with prognostic implications. We aimed to analyze comorbidity patterns in critically ill COVID-19 patients and assess their impact on in-hospital outcomes, response to treatment and sequelae. Methods Multicenter prospective/retrospective observational study in intensive care units of 55 Spanish hospitals. 5866 PCR-confirmed COVID-19 patients had comorbidities recorded at hospital admission; clinical and biological parameters, in-hospital procedures and complications throughout the stay; and, clinical complications, persistent symptoms and sequelae at 3 and 6 months. Findings Latent class analysis identified 3 phenotypes using training and test subcohorts: low-morbidity (n=3385; 58%), younger and with few comorbidities; high-morbidity (n=2074; 35%), with high comorbid burden; and renal-morbidity (n=407; 7%), with chronic kidney disease (CKD), high comorbidity burden and the worst oxygenation profile. Renal-morbidity and high-morbidity had more in-hospital complications and higher mortality risk than low-morbidity (adjusted HR (95% CI): 1.57 (1.34-1.84) and 1.16 (1.05-1.28), respectively). Corticosteroids, but not tocilizumab, were associated with lower mortality risk (HR (95% CI) 0.76 (0.63-0.93)), especially in renal-morbidity and high-morbidity. Renal-morbidity and high-morbidity showed the worst lung function throughout the follow-up, with renal-morbidity having the highest risk of infectious complications (6%), emergency visits (29%) or hospital readmissions (14%) at 6 months (p<0.01). Interpretation Comorbidity-based phenotypes were identified and associated with different expression of in-hospital complications, mortality, treatment response, and sequelae, with CKD playing a major role. This could help clinicians in day-to-day decision making including the management of post-discharge COVID-19 sequelae. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Advanced Supports for Noble Metal Catalysts in Proton Exchange Membrane Water Electrolysers: A Review

Renewable and low-carbon hydrogen will contribute to a future climate-neutral economy as a fuel, clean energy carrier and feedstock. One of the main concerns when considering its production by the present proton exchange membrane water electrolysers (PEMWE) is the use of scarce and expensive noble metals as catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), because they contribute to increase the cost of the technology. Several strategies have been developed to overcome this drawback, such as optimising the catalyst loading in the electrodes and alloying or using alternative catalyst supports, always with the aim to maintain or even increase electrolyser performance and durability. In this review, we examine the latest developments in HER and OER catalysts intended for practical PEMWE systems, which point in the short term to the use of platinum and iridium nanoparticles highly dispersed at low loadings on conductive non-carbon supports. © 2023 Johnson Matthey.Peer reviewe

Synthesis and characterization of Au nanocatalyst on modifed bentonite and silica and their applications for solvent free oxidation of cyclohexene with molecular oxygen

In the present work, the selective liquid phase oxidation of cyclohexene mainly to 2-cyclohexe-1-one has been investigated over gold nanoparticles (GNPs) with molecular oxygen in a solvent-free condition. Gold nanoparticles were synthesised on two modified supports of silica and bentonite. In this respect the surface of silica and bentonite was modified with organic ligands consist of thiol and thioester groups. The catalysts were characterized by TEM, XPS, N2 adsorption/desorption, FT-IR, and CHNS techniques. TEM images show that the gold nanoparticles over modified bentonite and silica have diameters in the range 0f 50 and less than 10 nm, respectively. The results show that the catalytic activity of gold nanoparticles over modified silica, SiO2-pA-Acrylate-Thioamide-Au (0), is much better than the gold nanoparticles immobilized on the modified bentonite, MEDPT@CP-bentonite-Au (0). The catalytic activity over SiO2-pA-Acrylate-Thioamide-Au (0) recycled catalyst remained at a satisfactory state after at least 4 cycles. Activity tests were carried out in an autoclave under solvent-free conditions. In order to obtain maximum conversion, the reaction parameters such as reaction temperature and time were optimized. Under optimized conditions, a maximum of 92% conversion and 97% selectivity was achieved with the SiO2-pA-Acrylate-Thioamide-Au (0) catalyst.Thanks are due to the Iranian Nanotechnology Initiative and the Research Council of Isfahan University of Technology and Centre of Excellence in the Chemistry Department of Isfahan University of Technology for supporting of this work.Peer Reviewe

CSIC Cicerón 4.5 Electrocatalizadores para una transición energética sostenible

Datos técnicos: 3 minutos, color, español. Ficha técnica: Gabinete de Presidencia CSIC y Departamento de ComunicaciónPeer reviewe

Titanium carbide and carbonitride electrocatalyst supports: Modifying Pt-Ti interface properties by electrochemical potential cycling

Titanium carbide and carbonitride are expected to be good materials to replace carbon as electrocatalyst supports, since they are chemically stable in acidic media and possess high electrical conductivity. However, they eventually can be transformed to titanium oxide, which is a thermodynamically stable compound, at potentials higher than 0.9 V (vs. RHE) in acidic media. In this communication, we report an enhanced catalytic activity towards CO and methanol electrooxidation on TiC and TiCN materials induced by surface oxides at the Pt/support interface. In particular, the current density obtained for Pt/TiC, activated up to 1.0 V, is 2-fold higher than that achieved with the commercial PtRu/C catalyst, which is accepted to be one of the best catalysts for methanol oxidation reaction.This work was supported by the Spanish Science and Innovation Ministry under project CTQ2011-28913-CO2-O2. MR acknowledges the FPU-2012 program for nancial support.Peer Reviewe