Properties and DEFC tests of Nafion Functionalized titanate nanotubes composite membranes prepared by melt extrusion

Nafion based composites are promising materials to improve the performance of direct ethanol fuel cells. In this work, composite membranes of Nafion and titanate nanotubes functionalized with sulfonic acid groups were prepared by melt extrusion and tested in a direct ethanol fuel cell. Far and mid infrared spectroscopies evidenced the formation of ionic bridges between the sulfonic acid groups of both functionalized nanoparticles and the ionomer. Small angle X ray scattering measurements revealed that the melt extrusion method leads to an uniform distribution of the inorganic phase in the ionomer matrix. Such structural analysis indicated that the improved the proton conduction properties of the composites, even with the addition of a high concentration of functionalized nanoparticles, are an outcome of the synergistic ionic network due to the hydrid organic inorganic proton conducting phases. However, an improvement of the fuel cell performance is observed for 2.5 wt of functionalized titanate nanotubes, which is a result of the lower ethanol crossover and the plasticizing effect of the aliphatic segments of the organic moieties grafted at the surface of the titanate nanoparticle

Development of new systems of nano-disperse Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts tolerant to carbon monoxide (CO) for PEMFC anodes

The nanophase material (powder) of Ce0.9W0.1O2 was synthesized via coprecipitation of oxalates of cerium (IV) and tungsten cations. Pt-Ce0.9W0.1O2 (2 wt% Pt) was prepared by an alcohol-reduction process using H2PtCl6.6H2O as source of Pt, Ce0.9W0.1O2 as support and ethylene glycol as solvent and reducing agent. Pt-Ce0.9W0.1O2 was physically mixed with commercial Pt/C E-TEK (20 w% Pt) to produce the Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalyst. The prepared electrocatalysts were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and CO stripping. The performances of Pt/C E-TEK and Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts were tested in single fuel cell fed with a mixture H2/CO (100 ppm of CO). The results showed that the mixture of 2%Pt-Ce0.9W0.1O2 and Pt/C E-TEK increases the CO tolerance in a single fuel cell operating at 85 ºC compared with Pt/C E-TEK

Development Of New Systems Of Nano-disperse Pt-(2%pt-ce0.9w 0.1o2)/c Electrocatalysts Tolerant To Carbon Monoxide (co) For Pemfc Anodes

The nanophase material (powder) of Ce0.9W0.1O 2 was synthesized via coprecipitation of oxalates of cerium (IV) and tungsten cations. Pt-Ce0.9W0.1O2 (2 wt% Pt) was prepared by an alcohol-reduction process using H2PtCl 6.6H2O as source of Pt, Ce0.9W 0.1O2 as support and ethylene glycol as solvent and reducing agent. Pt-Ce0.9W0.1O2 was physically mixed with commercial Pt/C E-TEK (20 w% Pt) to produce the Pt-(2%Pt-Ce 0.9W0.1O2)/C electrocatalyst. The prepared electrocatalysts were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and CO stripping. The performances of Pt/C E-TEK and Pt-(2%Pt-Ce0.9W0.1O2)/C electrocatalysts were tested in single fuel cell fed with a mixture H2/CO (100 ppm of CO). The results showed that the mixture of 2%Pt-Ce0.9W 0.1O2 and Pt/C E-TEK increases the CO tolerance in a single fuel cell operating at 85°C compared with Pt/C E-TEK. ©The Electrochemical Society.431185189Du Melle, F., The global and urban environment: The need for clean power systems (1998) Journal of Power Sources, 71 (1-2), pp. 7-11Oliveira Neto, A., Farias, A.L., Dias, R.R., Brandalise, M., Linardi, M., Spinacé, E.V., Enhanced electro-oxidation of ethanol using PtSn/CeO2-C electrocatalyst prepared by an alcohol-reduction process (2008) Electrochemistry Communications, 10 (9), pp. 1315-1317Pamqvist, A.E.C., Wirde, M., Gelius, U., Muhammed, M., Surfaces of Doped Nanophase Cerium Oxide Catalysts (1999) NanoStructured Materials, 11 (8), pp. 995-1007Rothenberg, G., De Graaf, E.A., Bliek, A., Solvent-Free Synthesis of Rechargeable Solid Oxygen Reservoirs for Clean Hydrogen Oxidation (2003) Angew. Chem. Int. Ed., (42), pp. 3366-3368. , BartGu, D.M., Chu, Y.Y., Wang, Z.B., Jiang, Z.Z., Yin, G.P., Liu, Y., Methanol oxidation on Pt/CeO2-C electrocatalyst prepared by microwave-assisted ethylene glycol process (2010) Applied Catalysis B: Environmental, 102 (1-2), pp. 9-18Hou, Z., Yi, B., Lin, Z., Zhang, H., CO tolerance of PtRu-HxMeO3/C (Me = W, Mo) made by composite support method (2003) Journal of Power Sources, 123 (2), pp. 116-125Santiago, E.I., Batista, M.S., Assaf, M.E., Ticianelli, E.A., Mechanism of CO tolerance on Molybdenum-Based Electrocatalysts for PEMFC (2004) Journal of the Electrochemical Society, 151 (7), pp. A944-A94

At-admission prediction of mortality and pulmonary embolism in an international cohort of hospitalised patients with COVID-19 using statistical and machine learning methods

By September 2022, more than 600 million cases of SARS-CoV-2 infection have been reported globally, resulting in over 6.5 million deaths. COVID-19 mortality risk estimators are often, however, developed with small unrepresentative samples and with methodological limitations. It is highly important to develop predictive tools for pulmonary embolism (PE) in COVID-19 patients as one of the most severe preventable complications of COVID-19. Early recognition can help provide life-saving targeted anti-coagulation therapy right at admission. Using a dataset of more than 800,000 COVID-19 patients from an international cohort, we propose a cost-sensitive gradient-boosted machine learning model that predicts occurrence of PE and death at admission. Logistic regression, Cox proportional hazards models, and Shapley values were used to identify key predictors for PE and death. Our prediction model had a test AUROC of 75.9% and 74.2%, and sensitivities of 67.5% and 72.7% for PE and all-cause mortality respectively on a highly diverse and held-out test set. The PE prediction model was also evaluated on patients in UK and Spain separately with test results of 74.5% AUROC, 63.5% sensitivity and 78.9% AUROC, 95.7% sensitivity. Age, sex, region of admission, comorbidities (chronic cardiac and pulmonary disease, dementia, diabetes, hypertension, cancer, obesity, smoking), and symptoms (any, confusion, chest pain, fatigue, headache, fever, muscle or joint pain, shortness of breath) were the most important clinical predictors at admission. Age, overall presence of symptoms, shortness of breath, and hypertension were found to be key predictors for PE using our extreme gradient boosted model. This analysis based on the, until now, largest global dataset for this set of problems can inform hospital prioritisation policy and guide long term clinical research and decision-making for COVID-19 patients globally. Our machine learning model developed from an international cohort can serve to better regulate hospital risk prioritisation of at-risk patients. © The Author(s) 2024

Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100  M⊙, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93  Gpc−3 yr−1 in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits

First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data

International audienceWe report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7  [1/Hz]. At the frequency of best strain sensitivity, near 100 Hz, we set 90% confidence upper limits of 1.8×10-25. At the low end of our frequency range, 20 Hz, we achieve upper limits of 3.9×10-24. At 55 Hz we can exclude sources with ellipticities greater than 10-5 within 100 pc of Earth with fiducial value of the principal moment of inertia of 1038  kg m2

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

International audienceSpinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo

International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100−105 M⊙, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼150 M⊙ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200 M⊙ and effective aligned spin 0.8 at 0.056 Gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc−3 yr−1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]† Deceased, August 2020