Introducing Stacking Faults into Three-Dimensional Branched Nickel Nanoparticles for Improved Catalytic Activity.

Creating high surface area nanocatalysts that contain stacking faults is a promising strategy to improve catalytic activity. Stacking faults can tune the reactivity of the active sites, leading to improved catalytic performance. The formation of branched metal nanoparticles with control of the stacking fault density is synthetically challenging. In this work, we demonstrate that varying the branch width by altering the size of the seed that the branch grows off is an effective method to precisely tune the stacking fault density in branched Ni nanoparticles. A high density of stacking faults across the Ni branches was found to lower the energy barrier for Ni2+/Ni3+ oxidation and result in enhanced activity for electrocatalytic oxidation of 5-hydroxylmethylfurfural. These results show the ability to synthetically control the stacking fault density in branched nanoparticles as a basis for enhanced catalytic activity.

Barriers and facilitators of domain-specific physical activity: a systematic review of reviews.

BACKGROUND: Knowing what facilitates and hinders physical activity behaviour across domains (leisure, travel, work or education, and household) is central for the development of actions for more active lifestyles. Thus, the aim of this systematic review of reviews was to summarize the evidence on barriers and facilitators of domain-specific physical activity. METHODS: We included systematic reviews with or without meta-analysis that investigated the association between modifiable barriers and facilitators and levels of domain-specific physical activity. Reviews published until September 2020 were retrieved from PubMed, ISI Web of Science, Scopus, Regional Library of Medicine (BIREME), and PsycNET, and from the reference list of selected articles. Each review was screened by two independent reviewers for eligibility. Data extracted from selected papers included methodological aspects (number of primary studies, study designs, and age groups); physical activity domains and barriers and facilitators investigated; and direction of association. For each pair of barrier/facilitator and domain-specific physical activity, we recorded the number of positive, negative, and null associations reported across reviews. Quality assessment of each systematic review was performed using the AMSTAR-2 tool. RESULTS: Forty-four systematic reviews were selected. The evidence base was largest for leisure-time followed by travel-related physical activity. A very small number of reviews included physical activity in work, educational and domestic settings. Across all physical activity domains, factors related to the built environment were more abundant in the reviews than intra and interpersonal factors. Very consistent positive associations were observed between a range of intrapersonal factors and leisure-time physical activity, as well as moderately consistent evidence of positive association for general social support and support from family members. Evidence of moderate consistency was found for the positive association between transport-related physical activity and positive beliefs about consequences, walkability, and existence of facilities that support active travel. Evidence on barriers and facilitators for physical activity at work, educational, and domestic settings was limited in volume and consistency. CONCLUSIONS: Efforts and resources are required to diversify and strength the evidence base on barriers and facilitators of domain-specific physical activity, as it is still limited and biased towards the leisure domain and built environment factors. TRIAL REGISTRATION: PROSPERO CRD42020209710.

Clustering of Physical Activity and Sedentary Behavior Associated With Body Composition in Brazilian Older Adults.

This study described the clustering patterns of moderate to vigorous physical activity and sedentary time (ST) according to handgrip strength and investigated the association between identified clusters of fat and lean mass in older adults from southern Brazil. Objective measures were used for moderate to vigorous physical activity, ST, and body composition outcomes. Two-step cluster and linear regression analyses were conducted according to handgrip strength. Three clusters were identified: all-day sitters, sitters, and active sitters. The prevalence of clusters in the low-strength group was 58.2%, 22.8%, and 19.0%, respectively, while the prevalence of clusters in the high-strength group was 42.1%, 34.8%, and 23.1%, respectively. All-day sitters had 2.6% more fat mass than active sitters with low strength. High levels of ST characterized all cluster profiles; low strength, lack of moderate to vigorous physical activity, and high ST levels among older adults may indicate a subpopulation at a greater risk of overweight and obesity-related diseases.

The Influence of Nanoconfinement on Electrocatalysis.

The use of nanoparticles and nanostructured electrodes are abundant in electrocatalysis. These nanometric systems contain elements of nanoconfinement in different degrees, depending on the geometry, which can have a much greater effect on the activity and selectivity than often considered. In this Review, we firstly identify the systems containing different degrees of nanoconfinement and how they can affect the activity and selectivity of electrocatalytic reactions. Then we follow with a fundamental understanding of how electrochemistry and electrocatalysis are affected by nanoconfinement, which is beginning to be uncovered, thanks to the development of new, atomically precise manufacturing and fabrication techniques as well as advances in theoretical modeling. The aim of this Review is to help us look beyond using nanostructuring as just a way to increase surface area, but also as a way to break the scaling relations imposed on electrocatalysis by thermodynamics.

Preserving the Exposed Facets of Pt3Sn Intermetallic Nanocubes During an Order to Disorder Transition Allows the Elucidation of the Effect of the Degree of Alloy Ordering on Electrocatalysis.

Controlling which facets are exposed in nanocrystals is crucial to understanding different activity between ordered and disordered alloy electrocatalysts. We modify the degree of ordering of Pt3Sn nanocubes, while maintaining the shape and size, to enable a direct evaluation of the effect of the order on ORR catalytic activity. We demonstrate a 2.3-fold enhancement in specific activity by 60- and 30%-ordered Pt3Sn nanocubes compared to 95%-ordered. This was shown to be likely due to surface vacancies in the less-ordered particles. The greater order, however, results in higher stability of the electrocatalyst, with the more disordered nanoparticles showing the dissolution of tin and platinum species during electrocatalysis.

Controlling the Number of Branches and Surface Facets of Pd-Core Ru-Branched Nanoparticles to Make Highly Active Oxygen Evolution Reaction Electrocatalysts.

Producing stable but active materials is one of the enduring challenges in electrocatalysis and other types of catalysis. Producing branched nanoparticles is one potential solution. Controlling the number of branches and branch size of faceted branched nanoparticles is one of the major synthetic challenges to achieve highly active and stable nanocatalysts. Herein, we use a cubic-core hexagonal-branch mechanism to synthesize branched Ru nanoparticles with control over the size and number of branches. This structural control is the key to achieving high exposure of active {10-11} facets and optimum number of Ru branches that enables improved catalytic activity for oxygen evolution reaction while maintaining high stability.

Faceted Branched Nickel Nanoparticles with Tunable Branch Length for High-Activity Electrocatalytic Oxidation of Biomass.

Controlling the formation of nanosized branched nanoparticles with high uniformity is one of the major challenges in synthesizing nanocatalysts with improved activity and stability. Using a cubic-core hexagonal-branch mechanism to form highly monodisperse branched nanoparticles, we vary the length of the nickel branches. Lengthening the nickel branches, with their high coverage of active facets, is shown to improve activity for electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF), as an example for biomass conversion.

Cascade Reactions in Nanozymes: Spatially Separated Active Sites inside Ag-Core-Porous-Cu-Shell Nanoparticles for Multistep Carbon Dioxide Reduction to Higher Organic Molecules.

Enzymes can perform complex multistep cascade reactions by linking multiple distinct catalytic sites via substrate channeling. We mimic this feature in a generalized approach with an electrocatalytic nanoparticle for the carbon dioxide reduction reaction comprising a Ag core surrounded by a porous Cu shell, providing different active sites in nanoconfined volumes. The architecture of the nanozyme provides the basis for a cascade reaction, which promotes C-C coupling reactions. The first step occurs on the Ag core, and the subsequent steps on the porous copper shell, where a sufficiently high CO concentration due to the nanoconfinement facilitates C-C bond formation. The architecture yields the formation of n-propanol and propionaldehyde at potentials as low as -0.6 V vs RHE.

Direct Growth of Highly Strained Pt Islands on Branched Ni Nanoparticles for Improved Hydrogen Evolution Reaction Activity.

The direct growth of Pt islands on lattice mismatched Ni nanoparticles is a major synthetic challenge and a promising strategy to create highly strained Pt atoms for electrocatalysis. By using very mild reaction conditions, Pt islands with tunable strain were formed directly on Ni branched particles. The highly strained 1.9 nm Pt-island on branched Ni nanoparticles exhibited high specific activity and the highest mass activity for hydrogen evolution (HER) in a pH 13 electrolyte. These results show the ability to synthetically tune the size of the Pt islands to control the strain to give higher HER activity.

Formation of Branched Ruthenium Nanoparticles for Improved Electrocatalysis of Oxygen Evolution Reaction.

Branched nanoparticles are one of the most promising nanoparticle catalysts as their branch sizes and surfaces can be tuned to enable both high activity and stability. Understanding how the crystallinity and surface facets of branched nanoparticles affect their catalytic performance is vital for further catalyst development. In this work, a synthesis is developed to form highly branched ruthenium (Ru) nanoparticles with control of crystallinity. It is shown that faceted Ru branched nanoparticles have improved stability and activity in the oxygen evolution reaction (OER) compared with polycrystalline Ru nanoparticles. This work achieves a low 180 mV overpotential at 10 mA cm-2 for hours, demonstrating that record-high stability for Ru nanocrystals can be achieved while retaining high activity for OER. The superior electrocatalytic performance of faceted Ru branched nanoparticles is ascribed to the lower Ru dissolution rate under OER conditions due to low-index facets on the branch surfaces.

The use of a personal glucose meter for detecting procalcitonin through glucose encapsulated within liposomes.

Herein, a glucose meter-based immunosensing platform is developed that allows the quantification of procalcitonin (PCT) in whole blood samples. PCT is a biomarker for sepsis and its early detection would improve the safety of the patient, as the diagnostic process will be easier and faster. The method employs liposomes with encapsulated glucose as a signal generation tag, which are then used in a sandwich immunoassay by conjugating an antibody to the liposome. The optimal liposomes' size and concentration of encapsulated glucose is determined experimentally to be 200 nm and 27.8 mM, respectively. Upon the addition of a surfactant (Triton X-100), the glucose is released and a signal is detected with a personal glucose meter (PGM). This signal is directly proportional to the concentration of the PCT in the sample. The dynamic range of the assay developed was 0.153-15.38 nM, and could allow the detection of PCT as low as 0.15 nM. The assay showed a high selectivity toward PCT against other proteins such as C-reactive protein and human serum albumin and good reproducibility. This assay was able to quantitatively determine the amount of PCT in whole blood samples at clinically-relevant concentrations.

Clustering of Physical Activity and Sedentary Behavior Associated to Risk for Metabolic Syndrome in Older Adults.

This study aimed to investigate the clustering patterns of physical activity, sedentary time (ST), and breaks in ST, and the association between the identified clusters at risk for metabolic syndrome associated with obesity in older adults. Participants included 212 users of community health centers in Brazil. A questionnaire about sociodemographic characteristics was used to describe the sample, and physical activity, ST, and breaks in ST were evaluated using accelerometers. Waist circumference was measured as an indicator of the risk for metabolic syndrome. A two-step cluster analysis and logistic regression analysis were conducted. The following four clusters were identified: sitters (37.7%), inactive (28.3%), active (25.5%), and all-day sitters/lightly active (8.5%). Participants in the active cluster were 60% less likely to be at risk for metabolic syndrome. This study may contribute to a comprehensive understanding of which older adult groups need more attention in the context of community health centers.

Cubic-Core Hexagonal-Branch Mechanism To Synthesize Bimetallic Branched and Faceted Pd-Ru Nanoparticles for Oxygen Evolution Reaction Electrocatalysis.

A major synthetic challenge is to make metal nanoparticles with nanosized branches and well-defined facets for high-performance catalysts. Herein, we introduce a mechanism that uses the growth of hexagonal crystal structured branches off cubic crystal structured core nanoparticles. We control the growth to form Pd-core Ru-branch nanoparticles that have nanosized branches with low index Ru facets. We demonstrate that the branched and faceted structural features of the Pd-Ru nanoparticles retain high catalytic activity while also achieving high stability for the oxygen evolution reaction.

Electrocatalytic Nanoparticles That Mimic the Three-Dimensional Geometric Architecture of Enzymes: Nanozymes.

Enzymes are characterized by an active site that is typically embedded deeply within the protein shell thus creating a nanoconfined reaction volume in which high turnover rates occur. We propose nanoparticles with etched substrate channels as a simplified enzyme mimic, denominated nanozymes, for electrocatalysis. We demonstrate increased electrocatalytic activity for the oxygen reduction reaction using PtNi nanoparticles with isolated substrate channels. The PtNi nanoparticles comprise an oleylamine capping layer that blocks the external surface of the nanoparticles participating in the catalytic reaction. Oxygen reduction mainly occurs within the etched channels providing a nanoconfined reaction volume different from the bulk electrolyte conditions. The oxygen reduction reaction activity normalized by the electrochemically active surface area is enhanced by a factor of 3.3 for the nanozymes compared to the unetched nanoparticles and a factor of 2.1 compared to mesoporous PtNi nanoparticles that possess interconnecting pores.

Three-Dimensional Branched and Faceted Gold-Ruthenium Nanoparticles: Using Nanostructure to Improve Stability in Oxygen Evolution Electrocatalysis.

Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low-index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close-packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low-index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts.

High Performance Fe Porphyrin/Ionic Liquid Co-catalyst for Electrochemical CO2 Reduction.

The efficient and selective catalytic reduction of CO2 is a highly promising process for both of the storage of renewable energy as well as the production of valuable chemical feedstocks. In this work, we show that the addition of an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, in an aprotic electrolyte containing a proton source and FeTPP, promotes the in situ formation of the [Fe(0) TPP](2-) homogeneous catalyst at a less negative potential, resulting in lower overpotentials for the CO2 reduction (670 mV) and increased kinetics of electron transfer. This co-catalysis exhibits high Faradaic efficiency for CO production (93 %) and turnover number (2 740 000 after 4 hour electrolysis), with a four-fold increase in turnover frequency (TOF) when compared with the standard system without the ionic liquid.

Rheological changes and kinetics of water uptake by poly(ionic liquid)-based thin films.

Water uptake by thin films composed of the poly(ionic liquid) poly[diallyldimethylammonium bis(trifluoromethanesulfonyl)imide] (PDDATf2N) and the ionic liquid N,N-butylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr1.4Tf2N) was studied with a quartz crystal microbalance with dissipation. The data obtained for films with different compositions during the passage of dry and wet N2 flow through the films were simulated with the Kevin-Voigt viscoelastic model for assessment of the mass of uptake water as well as the viscoelastic parameters. Our results show that the ionic liquid acts as a plasticizer, reducing the rigidity of the film and decreasing the capacity of water uptake. Introduction to a Li salt (LiTf2N) increases the water uptake capacity and also affects both elastic and viscous parameters due to aggregation among the ions from the ionic liquid and Li(+). However, due to the preferable interaction of Li(+) ions with water molecules, these aggregates are broken when the film is hydrated. In short, the presence of water in such films affects their mechanical properties, which can reflect in their performances as solid state electrolytes and ion-conducting membranes for electrochemical applications.

Food consumption scale validation in VAMOS Program: a proposal to assess eating behavior changes in Brazil.

This study aimed to validate the frequency consumption scale (FCS) and establish cut-off points to assess changes in the eating behavior of participants in the VAMOS Program. The study was based on a community intervention conducted in 2019 in 70 Brazilian cities, with 458 adults from Primary Care. The questionnaire consisted of 12 questions about food frequency consumption. The questions were inserted into the analytical workflow, divided into the descriptive analysis, exploratory and confirmatory factor analysis (EFA), item response theory (IRT) modeling, and construction and validity of an applied questionnaire score. EFA indicated a two-factor structure, with three "healthy" (raw vegetables, fruits, and cooked vegetables) and three "unhealthy" (sugary drinks, sweets, and the replacement of meals with snacks) eating items. Items responses' probabilities indicate a daily consumption of two healthy and once or nonweekly consumption of unhealthy items. Finally, the four categories proposed for FCS can respond over time. Therefore, the FCS proposal can be used effectively for program nutrition evaluation. Furthermore, it is possible to attribute behavior change in Brazilian primary care users with six items.

Nanoconfinement Allows a Less Active Cascade Catalyst to Produce More C2+ Products in Electrochemical CO2 Reduction.

Enzymes with multiple distinct active sites linked by substrate channels combined with control over the solution environment near the active sites enable the formation of complex products from simple reactants via the confinement of intermediates. We mimic this concept to facilitate the electrochemical carbon dioxide reduction reaction using nanoparticles with a core that produces intermediate CO at different rates and a porous copper shell. CO2 reacts at the core to produce CO which then diffuses through the Cu to give higher order hydrocarbon molecules. By altering the rate of CO2 delivery, the activity of the CO producing site, and the applied potential, we show that the nanoparticle with lower activity for CO formation produces greater amounts of hydrocarbon products. This is attributed to a combination of higher local pH and the lower amount of CO, resulting in more stable nanoparticles. However, when lower amounts of CO2 were delivered to the core, the particles that are more active for CO formation produce more C3 products. The importance of these results is twofold. They show that in cascade reactions, more active intermediate producing catalysts do not necessarily give greater amounts of high-value products. The effect an intermediate producing active site has on the local solution environment around the secondary active site plays an important role. As the less active catalyst for producing CO also possesses greater stability, we show that nanoconfinement can be used to get the best of both worlds with regard to having a stable catalyst with high activity.

Anthropometric profiles of elite older triathletes in the Ironman Brazil compared with those of young Portuguese triathletes and older Brazilians.

The objective of this study was to describe the anthropometric profiles of elite older triathletes participating in the 2009 Ironman Brazil and to compare their somatotype, anthropometric and body composition characteristics with those of elite young triathletes and older non-athletes. The sample consisted of 64 males, divided into three groups: (1) older triathletes (n = 17), (2) young triathletes (n = 24), and (3) older non-athletes (n = 23). Somatotype was analysed according to the Carter and Heath ( 1990 ) method. Body mass index, sum of four skinfolds, percentage body fat, body fat mass, and fat-free mass were also estimated. Older non-athletes had higher endomorphy, sum of four skinfolds, fat percentage, and body fat mass than the athletes. Older athletes who participated in the Ironman and elite young triathletes had higher fat-free mass than older non-athletes. Older triathletes and older non-athletes were considered mainly endomorphic mesomorphs and young triathletes mainly ectomorphic mesomorphs. The findings that characterize the anthropometric profile of athletes in this sports modality could be used as a reference.