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1.
Front Cardiovasc Med ; 11: 1324537, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38481954

RESUMEN

Introduction: Atherosclerotic cardiovascular disease (ASCVD) is one of the main causes of morbidity and mortality in developed countries and entails high resources use and costs for health systems. The risk of suffering future cardiovascular (CV) events and the consequent resources use is higher in those patients who have already had a previous cardiovascular event. The objective of the study was to determine the average annual cost of patients with a new or recurrent atherosclerotic CV event during the 2 years after the event. Methodology: Retrospective observational study of electronic medical records of patients from the BIG-PAC® database (7 integrated health areas of 7 Autonomous Communities; n = 1.8 million). Patients with a new or recurrent episode of ASCVD (angina, acute myocardial infarction, transient ischemic attack, stroke, or peripheral arterial disease) between 1-Jan-2017 and 31-Dec-2018 were included. The resources use within two years of the diagnosis was estimated in order to estimate the average cost of patient follow-up. Results: A total of 26,976 patients with an ASCVD episode were identified during the recruitment period; Out of them, 6,798 had a recurrent event during the follow-up period and 2,414 died. The average costs per patient were €11,171 during the first year and €9,944 during the second year. Discussion: Patients with ASCVD represent a significant economic burden for the health system and for society. Despite the perception that drug costs in the follow-up of chronic patients imply a high percentage of the costs, these accounted for only one tenth of the total amount. Implementing preventive programs and increasing the control of cardiovascular risk factors may have a significant social and health impact by helping to reduce mortality and costs for the Spanish National Health System. The costs derived from pharmacological treatments were obtained from the NHS pricing nomenclator database (https://www.sanidad.gob.es/profesionales/nomenclator.do).

2.
ACS Appl Mater Interfaces ; 15(22): 27173-27182, 2023 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-37222163

RESUMEN

The present article entails a novel concept of storing extra energy in a multifunctional polymer electrolyte membrane (PEM) beyond the storage capacity of a cathode, which is achieved by so-called "prelithiation" upon simply deep discharging to a low potential range of a lithium-metal electrode (i.e., -0.5 to 0.5 V). This unique extra energy-storage capacity has been realized recently in the PEM consisting of polysulfide-co-polyoxide conetworks in conjunction with succinonitrile and LiTFSI salt that facilitate complexation via ion-dipole interaction of dissociated lithium ions with thiols, disulfide, or ether oxygen of the conetwork. Although ion-dipole complexation may increase the cell resistance, the prelithiated PEM provides excess lithium ions during oxidation (or Li+ stripping) at the Li-metal electrode. Once the PEM network is fully saturated with Li ions, the remaining excess ions can move through the complexation sites at ease, thereby affording not only facile ion transport but also extra ion-storage capacity within the PEM conetwork. Of particular interest is that the lithiated polysulfide-co-polyoxide polymer network-based PEM exhibits a high conductivity of 1.18 × 10-3 S/cm at ambient, which can also store extra energy with a specific capacity of about 150 mAh/g at a 0.1C rate in the PEM voltage range of 0.01-3.5 V in addition to 165 mAh/g at 0.2C of an NMC622 (nickel manganese cobalt oxide) cathode (i.e., 2.5-4.6 V) with a Coulombic efficiency of approximate unity. Moreover, its Li-metal battery assembly with an NMC622 cathode exhibits a very high specific capacity of ∼260 mAh/g at 0.2C in the full battery range of 0.01-5 V, having a higher Li+ transference number of 0.74, suggestive of domination by the lithium cation transport relative to those (0.22-0.35) of organic liquid electrolyte lithium-ion batteries.

3.
Front Cardiovasc Med ; 9: 966049, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35990965

RESUMEN

Background: Atherosclerotic cardiovascular diseases (ASCVD) and dyslipidemia are associated to a higher risk of cardiovascular events, mortality, use of healthcare resources and costs. In Spain, the evidence about the administration of lipid-lowering treatments in clinical practice, and their clinical effectiveness in patients with ASCVD and hypercholesterolemia and patients with FH is scarce. Therefore, a multidisciplinary working group of cardiologists, family physicians, internal medicine specialists and neurologists was gathered for the Reality study. The aim of this study is to describe the demographic and clinical characteristics, comorbidities, and concomitant medication of patients with ASCVD and hypercholesterolemia and of patients with familial hypercholesterolemia (FH). The use of healthcare resources and costs associated to the management of these diseases after their diagnosis were also considered. Methods: This is an observational and retrospective study, based on the BIG-PAC® database, which includes the electronic medical registries (EMRs) of 1.8 million people from 7 Autonomous Communities in Spain (including public primary care centers and hospitals). The study includes patients who had a new or recurrent episode of ASCVD during the recruitment period (from 01/01/2017 to 31/12/2018). The index date will be defined as the date of the ASCVD event, and the follow-up period will be 24 months. According to their first diagnosis in the database, patients will be classified as ASCVD (5 groups: stable/unstable angina, acute myocardial infarction, ischemic stroke, transient ischemic attack, and peripheral arterial disease) or FH. Discussion: This study aims to analyze the treatment patterns and use of healthcare resources of ASCVD and FH in Spain. The prevalence of these disorders will also be estimated. Due to the high morbidity and mortality associated with these diseases, it is expected that our study will provide useful information for healthcare systems and decision makers to improve the management of these disabling diseases.

4.
ChemSusChem ; 14(21): 4613-4614, 2021 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-34661970

RESUMEN

Invited for this month's cover are the groups of Prof. Vijay Ramani and Prof. Rohan Mishra at Washington University in St. Louis and their collaborators at Oak Ridge National Laboratory. The Full Paper itself is available at 10.1002/cssc.202101341.

5.
Proc Natl Acad Sci U S A ; 118(34)2021 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-34417296

RESUMEN

Organic and organometallic reactants in aqueous electrolytes, being composed of earth-abundant elements, are promising redox active candidates for cost-effective organic redox flow batteries (ORFBs). Various compounds of ferrocene and methyl viologen have been examined as promising redox actives for this application. Herein, we examined the influence of the electrolyte pH and the salt anion on model redox active organic cations, bis((3-trimethylammonio) propyl)- ferrocene dichloride (BTMAP-Fc) and bis(3-trimethylammonio) propyl viologen tetrachloride (BTMAP-Vi), which have exhibited excellent cycling stability and capacity retention at ≥1.00 M concentration [E. S. Beh, et al. ACS Energy Lett. 2, 639-644 (2017)]. We examined the solvation shell around BTMAP-Fc and BTMAP-Vi at acidic and neutral pH with SO42-, Cl-, and CH3SO3- counterions and elucidated their impact on cation diffusion coefficient, first electron transfer rate constant, and thereby the electrochemical Thiele modulus. The electrochemical Thiele modulus was found to be exponentially correlated with the solvent reorganizational energy (λ) in both neutral and acidic pH. Thus, λ is proposed as a universal descriptor and selection criteria for organic redox flow battery electrolyte compositions. In the specific case of the BTMAP-Fc/BTMAP-Vi ORFB, low pH electrolytes with methanesulfonate or chloride counterions were identified as offering the best balance of transport and kinetic requirements.

6.
ChemSusChem ; 14(21): 4680-4689, 2021 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-34383996

RESUMEN

Clusters of nitrogen- and carbon-coordinated transition metals dispersed in a carbon matrix (e. g., Fe-N-C) have emerged as an inexpensive class of electrocatalysts for the oxygen reduction reaction (ORR). Here, it was shown that optimizing the interaction between the nitrogen-coordinated transition metal clusters embedded in a more stable and corrosion-resistant carbide matrix yielded an ORR electrocatalyst with enhanced activity and stability compared to Fe-N-C catalysts. Utilizing first-principles calculations, an electrostatics-based descriptor of catalytic activity was identified, and nitrogen-coordinated iron (FeN4 ) clusters embedded in a TiC matrix were predicted to be an efficient platinum-group metal (PGM)-free ORR electrocatalyst. Guided by theory, selected catalyst formulations were synthesized, and it was demonstrated that the experimentally observed trends in activity fell exactly in line with the descriptor-derived theoretical predictions. The Fe-N-TiC catalyst exhibited enhanced activity (20 %) and durability (3.5-fold improvement) compared to a traditional Fe-N-C catalyst. It was posited that the electrostatics-based descriptor provides a powerful platform for the design of active and stable PGM-free electrocatalysts and heterogenous single-atom catalysts for other electrochemical reactions.

7.
PLoS One ; 15(7): e0236032, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32687492

RESUMEN

BACKGROUND: We analyzed the effect of time to initiation of antiretroviral therapy (ART) after diagnosis on the probability of HIV-1 transmission events (HIV-TE) in naïve HIV-1-infected men having sex with men (MSM). SETTING: Mathematical model. METHODS: We used discrete event simulation modeling to estimate the probability of HIV-TE in the first 8 weeks after ART initiation; we varied ART initiation from D0 to D28 after simulated "diagnosis". The model inputs used sexual behavior parameters from the MSM population of the START trial, and transmission rates per-sex act and HIV-1 RNA from recent meta-analyses. HIV-1 RNA decay curves were modeled from the databases of Single (efavirenz [EFV] v dolutegravir [DTG]), Spring-2 (raltegravir [RAL] v DTG), and Flamingo (darunavir/ritonavir [DRVr] v DTG) trials. RESULTS: We found that the number of HIV-TE per index patient in the first 8 weeks after ART initiation increased linearly for same-day ART to initiation on day 28. Small but statistically significant advantages of integrase strand transfer inhibitors (INSTI) over EFV and DRVr were found. CONCLUSIONS: Rapid, if not same-day initiation of INSTI-based ART to newly diagnosed HIV-infected MSM has the potential for substantial public health benefits related to decreases in HIV-TE.


Asunto(s)
Terapia Antirretroviral Altamente Activa , Infecciones por VIH/transmisión , VIH-1/efectos de los fármacos , Modelos Teóricos , Minorías Sexuales y de Género/estadística & datos numéricos , Femenino , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , Humanos , Masculino
8.
PLoS One ; 14(7): e0219802, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31323075

RESUMEN

BACKGROUND: Initiation of antiretroviral therapy (ART) for HIV infection using regimens that include integrase strand transfer inhibitors (INSTIs) is associated with a faster decline in HIV-1 RNA than what is observed with regimens that are anchored by other ART drug classes. We compared the impact of ART regimens that include dolutegravir (DTG), raltegravir (RAL), efavirenz (EFV), or darunavir/ritonavir (DRV/r), in treatment naïve men who have sex with men (MSM) on the probability of HIV-1 sexual transmission events (HIV-TE). SETTING: Mathematical model. METHODS: We used discrete event simulation modeling to estimate HIV-TE during the first 8 weeks after initiation of ART. HIV-1 RNA decay in men was modeled from the databases of three clinical trials: Single (DTG vs. EFV), Spring-2 (DTG vs. RAL) and Flamingo (DTG vs. DRV/r). RESULTS: All regimens substantially reduced the number of HIV-TE compared to no treatment. DTG led to fewer HIV-TE than its comparator in each of the three trials: 22.72% fewer transmissions than EFV; 0.52% fewer transmissions than RAL; and 38.67% fewer transmissions than DRV/r. The number of patients needed to treat with DTG to prevent one transmission event instead of comparator was 48 vs EFV, 2,194 vs RAL, and 31 vs DRV/r. CONCLUSION: Unsurprisingly, this mathematical model showed that all regimens reduced HIV-TE compared to no treatment. The results also suggest that that initial use of INSTIs, by virtue of their superior viral decay kinetics, have the potential to reduce HIV-1 horizontal transmission following initiation of ART in naïve MSM. TRIAL REGISTRATION: ClinicalTrials.gov NCT03183154.


Asunto(s)
Infecciones por VIH/epidemiología , Infecciones por VIH/transmisión , VIH-1 , Homosexualidad Masculina , Modelos Teóricos , Enfermedades Virales de Transmisión Sexual/epidemiología , Enfermedades Virales de Transmisión Sexual/transmisión , Terapia Antirretroviral Altamente Activa , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , Humanos , Masculino , Conducta Sexual , Enfermedades Virales de Transmisión Sexual/tratamiento farmacológico , Enfermedades Virales de Transmisión Sexual/virología , Carga Viral
10.
ChemSusChem ; 10(15): 3056-3062, 2017 08 10.
Artículo en Inglés | MEDLINE | ID: mdl-28657214

RESUMEN

The objectives of this study were: 1) to confirm superoxide anion radical (O2.- ) formation, and 2) to monitor in real time the rate of O2.- generation in an operating anion exchange membrane (AEM) fuel cell using in situ fluorescence spectroscopy. 1,3-Diphenlisobenzofuran (DPBF) was used as the fluorescent molecular probe owing to its selectivity and sensitivity toward O2.- in alkaline media. The activation energy for the in situ generation of O2.- during AEM fuel cell operation was estimated to be 18.3 kJ mol-1 . The rate of in situ generation of O2.- correlated well with the experimentally measured loss in AEM ion-exchange capacity and ionic conductivity attributable to oxidative degradation.


Asunto(s)
Membranas Artificiales , Superóxidos/análisis , Superóxidos/química , Intercambio Iónico , Espectrometría de Fluorescencia
11.
Phys Chem Chem Phys ; 18(29): 19705-12, 2016 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-27381009

RESUMEN

Anion exchange membranes (AEM) based on polyphenylene oxide (PPO) suffered quaternary-ammonium-cation-site degradation in alkaline environments. Surprisingly, the degradation rate was considerably faster in the presence of molecular oxygen. We postulated that the AEM cation-site catalyzes the reduction of dioxygen by hydroxide ions to yield the superoxide anion radical and the highly reactive hydroxyl free radical. We substantiated our hypothesis by using a phosphorous-containing spin trap (5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide) to detect the adducts for both free radicals in situ using (31)P-NMR spectroscopy.

12.
Farm. hosp ; 39(3): 161-170, mayo-jun. 2015. ilus, tab
Artículo en Español | IBECS | ID: ibc-141574

RESUMEN

Objetivo: Estimar el coste-efectividad (CE) de belimumab en aquellos pacientes con biomarcadores positivos y enfermedad activa a pesar del tratamiento estándar (TE) desde la perspectiva social española. Métodos: A partir de un modelo de microsimulación, que permite simular la evolución natural de la enfermedad, se estimó el CE de belimumab + TE vs. TE. Se consideró una duración del tratamiento de dos años y un horizonte temporal de toda la vida. La extrapolación de eficacia a largo plazo se basó en los ensayos clínicos de belimumab y en la cohorte de pacientes John Hopkins de Estados Unidos; los datos de utilidades se obtuvieron de la literatura. Se calcularon costes directos e indirectos en base a datos españoles publicados (Euros, 2014), aplicando una tasa de descuento (TD) del 3% tanto a costes como a efectos. Los resultados se expresaron como ratio coste-efectividad incremental (ICER) en términos de años de vida ganados (AVG) y años de vida ajustados por calidad (AVAC). Se realizaron análisis de sensibilidad determinísticos (TD al 0% y 5%, duración de tratamiento 5 años y exclusión de costes indirectos) así como probabilísticos (PSA). Resultados: El ICER de belimumab + TE vs. TE fue de 16.647 Euros/ AVG y 23.158 Euros/AVAC respectivamente. La variación de la TD supuso la mayor variación de los resultados respecto al escenario base. En el 68% de los escenarios simulados en el PSA, belimumab fue una alternativa coste-efectiva considerando como umbral 30.000 Euros/AVAC. Conclusiones: Belimumab puede considerarse una alternativa coste-efectiva desde la perspectiva social española (AU)


Objective: To estimate the cost-effectiveness of belimumab in patients with systemic lupus erythematosus (SLE) presenting positive biomarkers and active disease despite standard treatment (ST), from the Spanish social perspective. Methods: A microsimulation model was used to estimate the cost-effectiveness of belimumab plus ST versus ST alone. A treatment duration of two years with a life-time horizon were considered. Efficacy data were obtained from belimumab clinical trials and the evolution of the disease was simulated from John Hopkins' patient cohort data in the United States. Utility data were obtained from literature review. Direct and indirect costs were calculated based on Spanish published data (Euros, 2014), applying a discount rate (DR) of 3% to both costs and effects. Results were expressed as incremental cost-effectiveness ratio (ICER) in terms of gained life years (LY) and quality of life adjusted life years (QALYs). Probabilistic (PSA) and deterministic sensitivity analyses (DR of 0% and 5%, 5-years treatment duration and excluding indirect costs) were performed to determine the robustness of the model. Results: The incremental cost-effectiveness ratio (ICER) was 16,647 Euros per life year gained, with an incremental cost-utility ratio (ICUR) of 23,158 Euros per additional QALY gained. In 68% of the scenarios simulated in the PSA, belimumab was found to be a cost-effective alternative, considering a threshold of 30,000 Euros/ QALY. Conclusion: Belimumab can be regarded as a cost-effective alternative from the Spanish social perspective (AU)


Asunto(s)
Humanos , Lupus Eritematoso Sistémico/tratamiento farmacológico , Anticuerpos Monoclonales/farmacocinética , 50303 , Terapia Biológica , Calidad de Vida , Resultado del Tratamiento
13.
Farm Hosp ; 39(3): 161-70, 2015 May 01.
Artículo en Español | MEDLINE | ID: mdl-26005892

RESUMEN

OBJECTIVE: To estimate the cost-effectiveness of belimumab in patients with systemic lupus erythematosus (SLE) presenting positive biomarkers and active disease despite standard treatment (ST), from the Spanish social perspective. METHODS: A microsimulation model was used to estimate the cost-effectiveness of belimumab plus ST versus ST alone. A treatment duration of two years with a life-time horizon were considered. Efficacy data were obtained from belimumab clinical trials and the evolution of the disease was simulated from John Hopkins ´ patient cohort data in the United States. Utility data were obtained from literature review. Direct and indirect costs were calculated based on Spanish published data (€, 2014), applying a discount rate (DR) of 3% to both costs and effects. Results were expressed as incremental cost-effectiveness ratio (ICER) in terms of gained life years (LY) and quality of life adjusted life years (QALYs). Probabilistic (PSA) and deterministic sensitivity analyses (DR of 0% and 5%, 5-years treatment duration and excluding indirect costs) were performed to determine the robustness of the model. RESULTS: The incremental cost-effectiveness ratio (ICER) was 16,647€ per life year gained, with an incremental cost-utility ratio (ICUR) of 23,158€ per additional QALY gained. In 68% of the scenarios simulated in the PSA, belimumab was found to be a cost-effective alternative, considering a threshold of 30,000€/ QALY. CONCLUSION: Belimumab can be regarded as a cost-effective alternative from the Spanish social perspective.


Objetivo: Estimar el coste-efectividad (CE) de belimumab en aquellos pacientes con biomarcadores positivos y enfermedad activa a pesar del tratamiento estandar (TE) desde la perspectiva social espanola. Métodos: A partir de un modelo de microsimulacion, que permite simular la evolucion natural de la enfermedad, se estimo el CE de belimumab + TE vs. TE. Se considero una duracion del tratamiento de dos anos y un horizonte temporal de toda la vida. La extrapolacion de eficacia a largo plazo se baso en los ensayos clinicos de belimumab y en la cohorte de pacientes John Hopkins de Estados Unidos; los datos de utilidades se obtuvieron de la literatura. Se calcularon costes directos e indirectos en base a datos espanoles publicados (€, 2014), aplicando una tasa de descuento (TD) del 3% tanto a costes como a efectos. Los resultados se expresaron como ratio coste- efectividad incremental (ICER) en terminos de anos de vida ganados (AVG) y anos de vida ajustados por calidad (AVAC). Se realizaron analisis de sensibilidad deterministicos (TD al 0% y 5%, duracion de tratamiento 5 anos y exclusion de costes indirectos) asi como probabilisticos (PSA). Resultados: El ICER de belimumab + TE vs. TE fue de 16.647€/ AVG y 23.158€/AVAC respectivamente. La variacion de la TD supuso la mayor variacion de los resultados respecto al escenario base. En el 68% de los escenarios simulados en el PSA, belimumab fue una alternativa coste-efectiva considerando como umbral 30.000€/AVAC. Conclusiones: Belimumab puede considerarse una alternativa coste-efectiva desde la perspectiva social espanola.


Asunto(s)
Anticuerpos Monoclonales Humanizados/economía , Anticuerpos Monoclonales Humanizados/uso terapéutico , Inmunosupresores/economía , Inmunosupresores/uso terapéutico , Lupus Eritematoso Sistémico/tratamiento farmacológico , Lupus Eritematoso Sistémico/economía , Anciano , Análisis Costo-Beneficio , Costos de los Medicamentos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Años de Vida Ajustados por Calidad de Vida , España
14.
Proc Natl Acad Sci U S A ; 111(1): 45-50, 2014 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-24367118

RESUMEN

We report a unique and highly stable electrocatalyst-platinum (Pt) supported on titanium-ruthenium oxide (TRO)-for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed to induce degradation and failure mechanisms identical to those seen during extended normal operation of a fuel cell automobile-namely, support corrosion during vehicle startup and shutdown, and platinum dissolution during vehicle acceleration and deceleration. These experiments were performed both ex situ (on supports and catalysts deposited onto a glassy carbon rotating disk electrode) and in situ (in a membrane electrode assembly). The Pt/TRO was compared against a state-of-the-art benchmark catalyst-Pt supported on high surface-area carbon (Pt/HSAC). In ex situ tests, Pt/TRO lost only 18% of its initial oxygen reduction reaction mass activity and 3% of its oxygen reduction reaction-specific activity, whereas the corresponding losses for Pt/HSAC were 52% and 22%. In in situ-accelerated degradation tests performed on membrane electrode assemblies, the loss in cell voltage at 1 A · cm(-2) at 100% RH was a negligible 15 mV for Pt/TRO, whereas the loss was too high to permit operation at 1 A · cm(-2) for Pt/HSAC. We clearly show that electrocatalyst support corrosion induced during fuel cell startup and shutdown is a far more potent failure mode than platinum dissolution during fuel cell operation. Hence, we posit that the need for a highly stable support (such as TRO) is paramount. Finally, we demonstrate that the corrosion of carbon present in the gas diffusion layer of the fuel cell is only of minor concern.

15.
Phys Chem Chem Phys ; 15(36): 14994-5002, 2013 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-23912796

RESUMEN

The oxygen permeability of perfluorinated and hydrocarbon polymer electrolyte membranes (PEMs; Nafion®, SPEEK and SPSU), which are used as electrolytes and electrode ionomers in polymer electrolyte fuel cells (PEFCs), was estimated using chronoamperometry using a modified fuel cell set-up. A thin, cylindrical microelectrode was embedded into the PEM and used as the working electrode. The PEM was sandwiched between 2 gas diffusion electrodes, one of which was catalyzed and served as the counter and pseudo-reference electrode. Independently, from fuel cell experiments, the oxygen transport resistance arising due to transport through the ionomer film covering the catalyst active sites was estimated at the limiting current and decoupled from the overall mass transport resistance. The in situ oxygen permeability measured at 80 °C and 75% RH of perfluorinated ionomers such as Nafion® (3.85 × 10(12) mol cm(-1) s(-1)) was observed to be an order of magnitude higher than that of hydrocarbon-based PEMs such as SPEEK (0.27 × 10(12) mol cm(-1) s(-1)) and SPSU (0.15 × 10(12) mol cm(-1) s(-1)). The obtained oxygen transport (through ionomer film) resistance values (Nafion® - 1.6 s cm(-1), SPEEK - 2.2 s cm(-1) and SPSU - 3.0 s cm(-1); at 80 °C and 75% RH) correlated well with the measured oxygen permeabilities in these ion-containing polymers.

16.
ACS Appl Mater Interfaces ; 4(10): 5098-102, 2012 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-22999007

RESUMEN

Nonstoichiometric CeO(2) and Ce(0.25)Zr(0.75)O(2) nanoparticles with varying surface concentrations of Ce(3+) were synthesized. Their surface Ce(3+) concentration was measured by XPS, and their surface oxygen vacancy concentrations and grain size were estimated using Raman spectroscopy. The surface oxygen vacancy concentration was found to correlate well with grain size and surface Ce(3+) concentration. When incorporated into a Nafion polymer electrolyte membrane (PEM), the added nonstoichiometric ceria nanoparticles effectively scavenged PEM-degradation-inducing free radical reactive oxygen species (ROS) formed during fuel cell operation. A 3-fold increase in the surface oxygen vacancy concentration resulted in an order of magnitude enhancement in the efficacy of free radical ROS scavenging by the nanoparticles. Overall, the macroscopic PEM degradation mitigation rate was lowered by up to 2 orders of magnitude using nonstoichiometric ceria nanoparticles with high surface oxygen vacancy concentrations.

17.
Chem Commun (Camb) ; 47(41): 11549-51, 2011 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-21952212

RESUMEN

CeO(2), Pt/CeO(2) and MnO(2) additives were found to lower the rate of free radical induced polymer electrolyte membrane degradation in an operating fuel cell by over one order of magnitude.

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