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1.
Langmuir ; 40(23): 12288-12300, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38805399

RESUMO

Over the past decades, the electrochemical CO2-reduction reaction (CO2RR) has emerged as a promising option for facilitating intermittent energy storage while generating industrial raw materials of economic relevance such as CO. Recent studies have reported that Au-Cu bimetallic nanocatalysts feature a superior CO2-to-CO conversion as compared with the monometallic components, thus improving the noble metal utilization. Under this premise and with the added advantage of a suppressed H2-evolution reaction due to absence of a carbon support, herein, we employ bimetallic Au3Cu and AuCu aerogels (with a web thickness ≈7 nm) as CO2-reduction electrocatalysts in 0.5 M KHCO3 and compare their performance with that of a monometallic Au aerogel. We supplement this by investigating how the CO2RR-performance of these materials is affected by their surface composition, which we modified by systematically dissolving a part of their Cu-content using cyclic voltammetry (CV). To this end, the effect of this CV-driven composition change on the electrochemical surface area is quantified via Pb underpotential deposition, and the local structural and compositional changes are visually assessed by employing identical-location transmission electron microscopy and energy-dispersive X-ray analyses. When compared to the pristine aerogels, the CV-treated samples displayed superior CO Faradaic efficiencies (≈68 vs ≈92% for Au3Cu and ≈34 vs ≈87% for AuCu) and CO partial currents, with the AuCu aerogel outperforming the Au3Cu and Au counterparts in terms of Au-mass normalized CO currents among the CV-treated samples.

2.
BMJ Open ; 13(6): e068938, 2023 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-37308273

RESUMO

OBJECTIVES: To validate the diagnoses of acute myocardial infarction (AMI) and stroke recorded in electronic medical records (EMR) and to estimate the population prevalence of both diseases in people aged ≥18 years. DESIGN: Cross-sectional validation study. SETTING: 45 primary care centres. PARTICIPANTS: Simple random sampling of diagnoses of AMI and stroke (International Classification of Primary Care-2 codes K75 and K90, respectively) registered by 55 physicians and random age-matched and sex-matched sampling of the records that included in primary care EMRs in Madrid (Spain). PRIMARY AND SECONDARY OUTCOME MEASURES: Sensitivity, specificity, positive and negative predictive values and overall agreement were calculated using the kappa statistic. Applied gold standards were ECGs, brain imaging studies, hospital discharge reports, cardiology reports and neurology reports. In the case of AMI, the ESC/ACCF/AHA/WHF Expert Consensus Document was also used. Secondary outcomes were the estimated prevalence of both diseases considering the sensitivity and specificity obtained (true prevalence). RESULTS: The sensitivity of a diagnosis of AMI was 98.11% (95% CI, 96.29 to 99.03), and the specificity was 97.42% (95% CI, 95.44 to 98.55). The sensitivity of a diagnosis of stroke was 97.56% (95% CI, 95.56 to 98.68), and the specificity was 94.51% (95% CI, 91.96 to 96.28). No differences in the results were found after stratification by age and sex (both diseases). The prevalence of AMI and stroke was 1.38% and 1.27%, respectively. CONCLUSION: The validation results show that diagnoses of AMI and stroke in primary care EMRs constitute a helpful tool in epidemiological studies. The prevalence of AMI and stroke was lower than 2% in the population aged over 18 years.


Assuntos
Infarto do Miocárdio , Acidente Vascular Cerebral , Humanos , Adulto , Pessoa de Meia-Idade , Adolescente , Estudos Transversais , Registros Eletrônicos de Saúde , Espanha , Alta do Paciente
3.
ACS Appl Mater Interfaces ; 15(22): 26538-26553, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37229747

RESUMO

The complex nature of liquid water saturation of polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) greatly affects the device performance. To investigate this problem, we present a method to quantify the presence of liquid water in a PEFC CL using small-angle X-ray scattering (SAXS). This method leverages the differences in electron densities between the solid catalyst matrix and the liquid water filled pores of the CL under both dry and wet conditions. This approach is validated using ex situ wetting experiments, which aid the study of the transient saturation of a CL in a flow cell configuration in situ. The azimuthally integrated scattering data are fitted using 3D morphology models of the CL under dry conditions. Different wetting scenarios are realized in silico, and the corresponding SAXS data are numerically simulated by a direct 3D Fourier transformation. The simulated SAXS profiles of the different wetting scenarios are used to interpret the measured SAXS data which allows the derivation of the most probable wetting mechanism within a flow cell electrode.

4.
J Am Chem Soc ; 145(14): 7845-7858, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-36988435

RESUMO

Non-noble metal catalysts (NNMCs) hold the potential to replace the expensive Pt-based materials currently used to speed up the oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC) cathodes, but they feature poor durability that inhibits their implementation in commercial PEMFCs. This performance decay is commonly ascribed to the operative demetallation of their ORR-active sites, the electro-oxidation of the carbonaceous matrix that hosts these active centers, and/or the chemical degradation of the ionomer, active sites, and/or carbon support by radicals derived from the H2O2 produced as an ORR by-product. However, little is known regarding the relative contributions of these mechanisms to the overall PEMFC performance loss. With this motivation, in this study, we combined four degradation protocols entailing different cathode gas feeds (i.e., air vs N2), potential hold values, and durations to decouple the relative impact of the above deactivation mechanisms to the overall performance decay. Our results indicate that H2O2-related instability does not depend on the operative voltage but only on the ORR charge. Moreover, the electro-oxidation of the carbon matrix at high potentials (which for the catalyst tested herein triggers at 0.7 V) seems to be more detrimental to the NNMCs' activity than the demetallation occurring at low potentials.

5.
PLoS One ; 18(2): e0281657, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36758065

RESUMO

BACKGROUND: Latent autoimmune diabetes in adults (LADA) is a type of diabetes mellitus showing overlapping characteristics between type 1 Diabetes Mellitus and type 2 Diabetes Mellitus (T2DM), and autoimmunity against insulin-producing pancreatic cells. For its diagnosis, at least one type of anti-pancreatic islet antibody (GADAb is the most common) is required. Many authors recommend performing this measure in all newly diagnosed patients with DM, but it is not possible in Primary Health Care (PHC) due to its high cost. Currently, a relevant proportion of patients diagnosed as T2DM could be LADA. Confusing LADA with T2DM has clinical and safety implications, given its different therapeutic approach. The main objective of the study is to develop and validate a clinical score for identifying adult patients with DM at high risk of LADA in PHC. METHODS: This is an observational, descriptive, cross-sectional study carried out in Primary Care Health Centers with a centralized laboratory. All people over 30 years of age diagnosed with diabetes within a minimum of 6 months and a maximum of 4 years before the start of the study will be recruited. Individuals will be recruited by consecutive sampling. The study variables will be obtained through clinical interviews, physical examinations, and electronic medical records. The following variables will be recorded: those related to Diabetes Mellitus, sociodemographic, anthropometric, lifestyle habits, laboratory parameters, presence of comorbidities, additional treatments, personal or family autoimmune disorders, self-perceived health status, Fourlanos criteria, and LADA diagnosis (as main variable) according to current criteria. DISCUSSION: The study will provide an effective method for identifying patients at increased risk of LADA and, therefore, candidates for antibody testing. However, a slight participation bias is to be expected. Differences between participants and non-participants will be studied to quantify this potential bias.


Assuntos
Doenças Autoimunes , Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Intolerância à Glucose , Diabetes Autoimune Latente em Adultos , Humanos , Adulto , Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 2/diagnóstico , Estudos Transversais , Autoanticorpos , Doenças Autoimunes/diagnóstico , Atenção Primária à Saúde , Diabetes Autoimune Latente em Adultos/diagnóstico , Estudos Observacionais como Assunto
6.
Angew Chem Int Ed Engl ; 62(16): e202216633, 2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-36749547

RESUMO

In recent years, operando/in situ X-ray absorption spectroscopy (XAS) has become an important tool in the electrocatalysis community. However, the high catalyst loadings often required to acquire XA-spectra with a satisfactory signal-to-noise ratio frequently imply the use of thick catalyst layers (CLs) with large ion- and mass-transport limitations. To shed light on the impact of this variable on the spectro-electrochemical results, in this study we investigate Pd-hydride formation in carbon-supported Pd-nanoparticles (Pd/C) and an unsupported Pd-aerogel with similar Pd surface areas but drastically different morphologies and electrode packing densities. Our in situ XAS and rotating disk electrode (RDE) measurements with different loadings unveil that the CL-thickness largely determines the hydride formation trends inferred from spectro-electrochemical experiments, therewith calling for the minimization of the CL-thickness in such experiments and the use of complementary thin-film control measurements.

7.
Acc Chem Res ; 56(3): 237-247, 2023 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-36700845

RESUMO

ConspectusMetal aerogels assembled from nanoparticles have captured grand attention because they combine the virtues of metals and aerogels and are regarded as ideal materials to address current environmental and energy issues. Among these aerogels, those composed of two metals not only display combinations (superpositions) of the properties of their individual metal components but also feature novel properties distinctly different from those of their monometallic relatives. Therefore, quite some effort has been invested in refining the synthetic methods, compositions, and structures of such bimetallic aerogels as to boost their performance for the envisaged application(s). One such use would be in the field of electrocatalysis, whereby it is also of utmost interest to unravel the element distributions of the (multi)metallic catalysts to achieve a ratio of their bottom-to-up design. Regarding the element distributions in bimetallic aerogels, advanced characterization techniques have identified alloys, core-shells, and structures in which the two metal particles are segregated (i.e., adjacent but without alloy or core-shell structure formation). While an almost infinite number of metal combinations to form bimetallic aerogels can be envisaged, the knowledge of their formation mechanisms and the corresponding element distributions is still in its infancy. The evolution of the observed musters is all but well understood, not to mention the positional changes of the elements observed in operando or in beginning- vs end-of-life comparisons (e.g., in fuel cell applications).With this motivation, in this Account we summarize the endeavors made in element distribution monitoring in bimetallic aerogels in terms of synthetic methods, expected structures, and their evolution during electrocatalysis. After an introductory chapter, we first describe briefly the two most important characterization techniques used for this, namely, scanning transmission electron microscopy (STEM) combined with element mapping (e.g., energy-dispersive X-ray spectroscopy (EDXS)) and X-ray absorption spectroscopy (XAS). We then explain the universal methods used to prepare bimetallic aerogels with different compositions. Those are divided into one-step methods in which gels formed from mixtures of the respective metal salts are coreduced and two-step approaches in which monometallic nanoparticles are mixed and gelated. Subsequently, we summarize the current state-of-knowledge on the element distributions unraveled using diverse characterization methods. This is extended to investigations of the element distributions being altered during electrochemical cycling or other loads. So far, a theoretical understanding of these processes is sparse, not to mention predictions of element distributions. The Account concludes with a series of remarks on current challenges in the field and an outlook on the gains that the field would earn from a solid understanding of the underlying processes and a predictive theoretical backing.

8.
Nanoscale ; 14(28): 10155-10168, 2022 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-35796244

RESUMO

Synthesizing metal nanoparticles with fine control of size, shape and surface properties is of high interest for applications such as catalysis, nanoplasmonics, and fuel cells. In this contribution, we demonstrate that the citrate-coated surfaces of palladium (Pd) and platinum (Pt)@Pd nanocubes with a lateral length <5 nm and low polydispersity in shape achieve superior catalytic properties. The synthesis achieves great control of the nanoparticle's physico-chemical properties by using only biogenic reagents and bromide ions in water while being fast, easy to perform and scalable. The role of the seed morphology is pivotal as Pt single crystal seeds are necessary to achieve low polydispersity in shape and prevent nanorods formation. In addition, electrochemical measurements demonstrate the abundancy of Pd{100} surface facets at a macroscopic level, in line with information inferred from TEM analysis. Quantum density functional theory calculations indicate that the kinetic origin of cubic Pd nanoshapes is facet-selective Pd reduction/deposition on Pd(111). Moreover, we underline both from an experimental and theoretical point of view that bromide alone does not induce nanocube formation without the synergy with formic acid. The superior performance of these highly controlled nanoparticles to perform the catalytic reduction of 4-nitrophenol was proved: polymer-free and surfactant-free Pd nanocubes outperform state-of-the-art materials by a factor >6 and a commercial Pd/C catalyst by more than one order of magnitude.

9.
ACS Mater Au ; 2(3): 278-292, 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35578702

RESUMO

The efficient scale-up of CO2-reduction technologies is a pivotal step to facilitate intermittent energy storage and for closing the carbon cycle. However, there is a need to minimize the occurrence of undesirable side reactions like H2 evolution and achieve selective production of value-added CO2-reduction products (CO and HCOO-) at as-high-as-possible current densities. Employing novel electrocatalysts such as unsupported metal aerogels, which possess a highly porous three-dimensional nanostructure, offers a plausible approach to realize this. In this study, we first quantify the electrochemical surface area of an Au aerogel (≈5 nm in web thickness) using the surface oxide-reduction and copper underpotential deposition methods. Subsequently, the aerogel is tested for its CO2-reduction performance in an in-house developed, two-compartment electrochemical cell. For comparison purposes, similar measurements are also performed on polycrystalline Au and a commercial catalyst consisting of Au nanoparticles supported on carbon black (Au/C). The Au aerogel exhibits a faradaic efficiency of ≈97% for CO production at ≈-0.48 VRHE, with a suppression of H2 production compared to Au/C that we ascribe to its larger Au-particle size. Finally, identical-location transmission electron microscopy of both nanomaterials before and after CO2-reduction reveals that, unlike Au/C, the aerogel network retains its nanoarchitecture at the potential of peak CO production.

10.
Phys Chem Chem Phys ; 23(15): 9147-9157, 2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33885106

RESUMO

Pt-group metal (PGM)-free catalysts of the Me-N-C type based on abundant and inexpensive elements have gained importance in the field of oxygen reduction reaction (ORR) electrocatalysis due to their promising ORR-activities. Their insufficient stability, however, has fueled the interest in obtaining an in-depth understanding of their composition, which requires highly sensitive techniques compatible with their low metal contents (typically <5 wt%). In the particular context of iron-based materials, 57Fe-Mössbauer spectroscopy is often used to provide such compositional information, but requires (partially) 57Fe-enriched precursors. As a consequence, the extrapolation of conclusions drawn from Mössbauer measurements on 57Fe-enriched catalysts to equivalent materials with the standard isotope distribution relies on the assumption that the metal precursor's isotopic profile does not affect the catalysts' composition and ORR-activity. To verify this hypothesis, in this study we prepared two series of Fe-based catalysts using distinctively different synthesis approaches and various relative contents of 57Fe-enriched precursors, and observed that the extent of the latter parameter significantly affected the catalysts' ORR-activity. This effect was successfully correlated with the Fe-speciation of the catalysts inferred from the characterization of these samples with Mössbauer and X-ray absorption spectroscopies. Ultimately, these results highlight the crucial importance of verifying the consistency of the catalysts' activity and composition upon comparing standard and 57Fe-enriched samples.

11.
ACS Appl Mater Interfaces ; 13(13): 15122-15131, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33764754

RESUMO

The electroreduction of carbon dioxide is considered a key reaction for the valorization of CO2 emitted in industrial processes or even present in the environment. Cobalt-nitrogen co-doped carbon materials featuring atomically dispersed Co-N sites have been shown to display superior activities and selectivities for the reduction of carbon dioxide to CO, which, in combination with H2 (i.e., as syngas), is regarded as an added-value CO2-reduction product. Such catalysts can be synthesized using heat treatment steps that imply the carbonization of Co-N-containing precursors, but the detailed effects of the synthesis conditions and corresponding materials' composition on their catalytic activities have not been rigorously studied. To this end, in the present work, we synthesized cobalt-nitrogen co-doped carbon materials with different heat treatment temperatures and studied the relation among their surface- and Co-speciation and their CO2-to-CO electroreduction activity. Our results reveal that atomically dispersed cobalt-nitrogen sites are responsible for CO generation while suggesting that this CO-selectivity improves when these atomic Co-N centers are hosted in the carbon layers that cover the Co nanoparticles featured in the catalysts synthesized at higher heat treatment temperatures.

12.
Angew Chem Int Ed Engl ; 60(21): 11707-11712, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-33605017

RESUMO

The commercial success of the electrochemical energy conversion technologies required for the decarbonization of the energy sector requires the replacement of the noble metal-based electrocatalysts currently used in (co-)electrolyzers and fuel cells with inexpensive, platinum-group metal-free analogs. Among these, Fe/N/C-type catalysts display promising performances for the reduction of O2 or CO2 , but their insufficient activity and stability jeopardize their implementation in such devices. To circumvent these issues, a better understanding of the local geometric and electronic structure of their catalytic active sites under reaction conditions is needed. Herein we shed light on the electronic structure of the molecular sites in two Fe/N/C catalysts by probing their average spin state with X-ray emission spectroscopy (XES). Chiefly, our in situ XES measurements reveal for the first time the existence of reversible, potential-induced spin state changes in these materials.

13.
Therap Adv Gastroenterol ; 13: 1756284819895435, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-35392297

RESUMO

Background: Gastric cancer is one of the most incident types of cancer worldwide and presents high mortality rates and poor prognosis. MYC oncogene overexpression is a key event in gastric carcinogenesis and it is known that its protein positively regulates CDC25B expression which, in turn, plays an essential role in the cell division cycle progression. Menadione is a synthetic form of vitamin K that acts as a specific inhibitor of the CDC25 family of phosphatases. Methods: To better understand the menadione mechanism of action in gastric cancer, we evaluated its molecular and cellular effects in cell lines and in Sapajus apella, nonhuman primates from the new world which had gastric carcinogenesis induced by N-Methyl-N-nitrosourea. We tested CDC25B expression by western blot and RT-qPCR. In-vitro assays include proliferation, migration, invasion and flow cytometry to analyze cell cycle arrest. In in-vivo experiments, in addition to the expression analyses, we followed the preneoplastic lesions and the tumor progression by ultrasonography, endoscopy, biopsies, histopathology and immunohistochemistry. Results: Our tests demonstrated menadione reducing CDC25B expression in vivo and in vitro. It was able to reduce migration, invasion and proliferation rates, and induce cell cycle arrest in gastric cancer cell lines. Moreover, our in-vivo experiments demonstrated menadione inhibiting tumor development and progression. Conclusions: We suggest this compound may be an important ally of chemotherapeutics in the treatment of gastric cancer. In addition, CDC25B has proven to be an effective target for investigation and development of new therapeutic strategies for this malignancy.

14.
Chemphyschem ; 20(22): 3120-3127, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31310028

RESUMO

The encouraging selectivity of copper oxides for the electroreduction of CO2 into ethylene and alcohols has led to a vivid debate on the possible relation between their operando (sub-)surface oxidation state (i. e. fully reduced or partially oxidized) and this distinct reactivity. The high roughness of the Cu oxides used in previous studies on this matter adds complexity to this controversy and motivated us to prepare quasi-planar Cu2 O thin films that displayed a CO2 reduction selectivity similar to that of oxide-derived copper catalysts reported in previous studies. Most importantly, when the post-mortem thin films were transferred for characterization in an air-free environment, X-ray photoelectron spectroscopy measurements confirmed their complete reduction in the course of the CO2 reduction reaction. Thus, our results indicate that the selectivity of the Cu oxides featured in previous studies stems from their enhanced roughness, highlighting the importance of controlled sample transfer upon post-mortem characterization with ex situ techniques.

15.
BMJ Open ; 8(9): e020768, 2018 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-30249627

RESUMO

OBJECTIVE: To estimate the prevalence of depression in patients diagnosed with type 2 diabetes mellitus (T2DM), and to identify sociodemographic, clinical and psychological factors associated with depression in this population. Additionally, we examine the annual incidence rate of depression among patients with T2DM. METHODS: We performed a large prospective cohort study of patients with T2DM from the Madrid Diabetes Study. The first recruitment drive included 3443 patients. The second recruitment drive included 727 new patients. Data have been collected since 2007 (baseline visit) and annually during the follow-up period (since 2008). RESULTS: Depression was prevalent in 20.03% of patients (n=592; 95% CI 18.6% to 21.5%) and was associated with previous personal history of depression (OR 6.482; 95% CI 5.138 to 8.178), mental health status below mean (OR 1.423; 95% CI 1.452 to 2.577), neuropathy (OR 1.951; 95% CI 1.423 to 2.674), fair or poor self-reported health status (OR 1.509; 95% CI 1.209 to 1.882), treatment with oral antidiabetic agents plus insulin (OR 1.802; 95% CI 1.364 to 2.380), female gender (OR 1.333; 95% CI 1.009 to 1.761) and blood cholesterol level (OR 1.005; 95% CI 1.002 to 1.009). The variables inversely associated with depression were: being in employment (OR 0.595; 95% CI 0.397 to 0.894), low physical activity (OR 0.552; 95% CI 0.408 to 0.746), systolic blood pressure (OR 0.982; 95% CI 0.971 to 0.992) and social support (OR 0.978; 95% CI 0.963 to 0.993). In patients without depression at baseline, the incidence of depression after 1 year of follow-up was 1.20% (95% CI 1.11% to 2.81%). CONCLUSIONS: Depression is very prevalent among patients with T2DM and is associated with several key diabetes-related outcomes. Our results suggest that previous mental status, self-reported health status, gender and several diabetes-related complications are associated with differences in the degree of depression. These findings should alert practitioners to the importance of detecting depression in patients with T2DM.


Assuntos
Depressão/epidemiologia , Diabetes Mellitus Tipo 2/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Depressão/psicologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/psicologia , Nefropatias Diabéticas/epidemiologia , Feminino , Nível de Saúde , Humanos , Incidência , Masculino , Transtornos Mentais/epidemiologia , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Fatores de Proteção , Fatores de Risco , Fatores Sexuais , Espanha/epidemiologia
16.
Nat Mater ; 17(9): 827-833, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30013055

RESUMO

Tuning the surface structure at the atomic level is of primary importance to simultaneously meet the electrocatalytic performance and stability criteria required for the development of low-temperature proton-exchange membrane fuel cells (PEMFCs). However, transposing the knowledge acquired on extended, model surfaces to practical nanomaterials remains highly challenging. Here, we propose 'surface distortion' as a novel structural descriptor, which is able to reconciliate and unify seemingly opposing notions and contradictory experimental observations in regards to the electrocatalytic oxygen reduction reaction (ORR) reactivity. Beyond its unifying character, we show that surface distortion is pivotal to rationalize the electrocatalytic properties of state-of-the-art of PtNi/C nanocatalysts with distinct atomic composition, size, shape and degree of surface defectiveness under a simulated PEMFC cathode environment. Our study brings fundamental and practical insights into the role of surface defects in electrocatalysis and highlights strategies to design more durable ORR nanocatalysts.

17.
Angew Chem Int Ed Engl ; 56(36): 10707-10710, 2017 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-28612940

RESUMO

Highly active and durable oxygen reduction catalysts are needed to reduce the costs and enhance the service life of polymer electrolyte fuel cells (PEFCs). This can be accomplished by alloying Pt with a transition metal (for example Ni) and by eliminating the corrodible, carbon-based catalyst support. However, materials combining both approaches have seldom been implemented in PEFC cathodes. In this work, an unsupported Pt-Ni alloy nanochain ensemble (aerogel) demonstrates high current PEFC performance commensurate with that of a carbon-supported benchmark (Pt/C) following optimization of the aerogel's catalyst layer (CL) structure. The latter is accomplished using a soluble filler to shift the CL's pore size distribution towards larger pores which improves reactant and product transport. Chiefly, the optimized PEFC aerogel cathodes display a circa 2.5-fold larger surface-specific ORR activity than Pt/C and maintain 90 % of the initial activity after an accelerated stress test (vs. 40 % for Pt/C).

18.
Chimia (Aarau) ; 71(4): 160-169, 2017 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-28446329

RESUMO

We present recent developments in top-down nanofabrication that have found application in catalysis research. To unravel the complexity of catalytic systems, the design and use of models with control of size, morphology, shape and inter-particle distances is a necessity. The study of well-defined and ordered nanoparticles on a support contributes to the understanding of complex phenomena that govern reactions in heterogeneous and electro-catalysis. We review the strengths and limitations of different nanolithography methods such as electron beam lithography (EBL), photolithography, extreme ultraviolet (EUV) lithography and colloidal lithography for the creation of such highly tunable catalytic model systems and their applications in catalysis. Innovative strategies have enabled particle sizes reaching dimensions below 10 nm. It is now possible to create pairs of particles with distance controlled with an extremely high precision in the order of one nanometer. We discuss our approach to study these model systems at the single-particle level using X-ray absorption spectroscopy and show new ways to fabricate arrays of single nanoparticles or nanoparticles in pairs over a large area using EBL and EUV-achromatic Talbot lithography. These advancements have provided new insights into the active sites in metal catalysts and enhanced the understanding of the role of inter-particle interactions and catalyst supports, such as in the phenomenon of hydrogen spillover. We present a perspective on future directions for employing top-down nanofabrication in heterogeneous and electrocatalysis. The rapid development in nanofabrication and characterization methods will continue to have an impact on understanding of complex catalytic processes.

19.
Vaccine ; 35(1): 101-108, 2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-27890398

RESUMO

OBJECTIVES: We aim to determine influenza vaccination uptake among people with diabetes included in the MADIABETES cohort study in order to identify predictors of uptake and to analyze reasons for adherence and non-adherence with vaccination. METHODS: Using data from the MADIABETES Study we conducted a retrospective case record form based study without controls. We included outpatients with type 2 diabetes mellitus. Information was obtained from computerized clinical records and by telephone survey. The main dependent variables were influenza vaccination uptake in the year 2013 and the reason for receiving or refusing vaccination. RESULTS: Overall, 65.7% had received the influenza vaccine in 2013. The mean number of influenza vaccines received from 2007 to 2013 was 3.24 (SD1.15), although 19.23% had not received any influenza vaccine and 23.3% had been vaccinated against pneumococcus. The variables that increased the probability of being vaccinated were inclusion in the age-based recommendation (⩾60years), having a chronic respiratory disease, previous pneumococcal vaccination, higher number of visits to the general practitioner, higher number of influenza vaccines, and longer time since diabetes diagnosis. A higher mean glycated haemoglobin value in 2013 was associated with a reduced probability of vaccination. Most patients (90%) agreed to be vaccinated following their physician's advice because of their age or their chronic conditions. The most common reason for refusal among men was the belief that they were not at risk (41.6% vs. 29.79% in women); the most common reason for refusal among women was fear of adverse reactions (32.53% vs. 20.23% in men). CONCLUSIONS: The uptake of influenza vaccination among diabetic patients in the present study was below desirable levels. The main barrier to vaccination was lack of knowledge regarding the need for and risks and advantages of influenza vaccination. Healthcare professionals should educate and encourage influenza vaccination among people with diabetes.


Assuntos
Complicações do Diabetes/prevenção & controle , Diabetes Mellitus Tipo 2/complicações , Conhecimentos, Atitudes e Prática em Saúde , Vacinas contra Influenza/administração & dosagem , Influenza Humana/prevenção & controle , Vacinação/psicologia , Vacinação/estatística & dados numéricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde , Estudos Retrospectivos
20.
J Diabetes Complications ; 30(2): 227-36, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26627635

RESUMO

AIMS: To assess the prevalence of stage 3-5 chronic kidney disease (CKD) at baseline and to identify associated risk factors. To determine the effect of CKD and CKD stage according to estimated glomerular filtration rate (eGFR) and albuminuria categories on all-cause and cardiovascular mortality after a 5-year follow-up. METHODS: Prospective cohort study of 3443 outpatients with type 2 diabetes mellitus. RESULTS: The prevalence of CKD was 28.32% (95% CI, 26.84-29.86); and variables most strongly associated were: age >74 years (OR, 19.88; 95% CI, 12.89-30.68) and albuminuria (OR, 2.27; 95% CI, 1.72-3.00). During follow-up, 221 CKD patients (22.90%) died compared with 203 non-CKD patients (8.31%) (p<0.01). The adjusted HR of CKD for cardiovascular and all-cause mortality was 1.82 (95% CI, 1.36-2.44) and 2.11 (95% CI, 1.61-2.76) for those with LDL cholesterol =135 mg/dl, respectively. The adjusted HR of very-high-risk CKD for all-cause mortality was 4.44 (95% CI, 2.31-8.53) in aged <75 years and 1.80 (95% CI, 1.19-2.72) in aged ≥75 years. CONCLUSIONS: CKD at baseline is an independent risk factor for all-cause and cardiovascular mortality in the overall cohort, men and women, or in primary and secondary prevention of coronary heart disease. Albuminuria is an independent risk factor for all-cause and cardiovascular mortality only in primary prevention.


Assuntos
Doenças Cardiovasculares/mortalidade , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/mortalidade , Angiopatias Diabéticas/mortalidade , Nefropatias Diabéticas/mortalidade , Insuficiência Renal Crônica/mortalidade , Idoso , Idoso de 80 Anos ou mais , Doenças Cardiovasculares/complicações , Causas de Morte , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/complicações , Espanha/epidemiologia
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