Ni–Fe and Ni–Fe–Co mixed-metal oxide (MMO) films were investigated as electrocatalysts for the oxygen evolution reaction (OER) in 0.1 M KOH. In an effort to optimize MMO morphology, aniline was used ...as a capping agent to produce high-surface-area Ni–Fe–Co films on Raney nickel supports. This catalyst exhibits enhanced mass activity in comparison to the Ni–Fe OER electrocatalysts reported to date. Cyclic voltammetry shows changes in the potential of the Ni2+/3+ transitions in Fe- or Co-containing MMO films. In situ X-ray absorption spectroscopy (XAS) analysis confirms that Fe acts to stabilize Ni in the 2+ oxidation state, while Co facilitates oxidation to the 3+ state. The results of this study support the recent claims that Fe (not Ni) is the OER active site. The OER enhancement of the ternary Ni–Fe–Co catalyst results from two effects: (1) the charge-transfer effects of Co result in the formation of the conductive NiIIIOOH phase at lower overpotential, thus activating the Fe sites which are otherwise inaccessible to electron transfer in the nonconductive NiII(OH)2 host lattice, and (2) XAS analysis shows that the presence of Co effectively “shrinks” the Ni and Fe local geometry, likely resulting in an optimized Fe–OH/OOH bond strength. In addition, analysis of heat-treatment effects indicates that calcination at 400 °C improves the OER activity of Ni–Fe–Co but deactivates Ni–Fe. Annealing studies under argon show that MMO surfaces with a hydrated Ni(OH)2 phase and a crystalline NiO phase exhibit nearly identical OER activities. Finally, the morphology of the MMO catalyst film on Raney Ni support provides excellent catalyst dispersion and should result in high active-site utilization for use in technologically relevant gas-diffusion electrodes.
Objective
To assess the relationship between measures of disease assessment in patients with large vessel vasculitis.
Methods
Patients with giant cell arteritis (GCA) or Takayasu arteritis (TAK) were ...recruited into a prospective, observational cohort. Assessments within the following outcomes were independently recorded: 1) patient‐reported outcomes (Multidimensional Fatigue Inventory, patient global assessment of disease activity PtGA, Short Form 36 health survey SF‐36, Brief Illness Perception Questionnaire), 2) physician global assessment of disease activity (PhGA), 3) laboratory outcomes (C‐reactive protein CRP level, erythrocyte sedimentation rate ESR), and 4) imaging outcomes (PETVAS, a qualitative score of vascular 18F‐fluorodeoxyglucose–positron emission tomography activity).
Results
Analyses were performed on 112 patients (GCA = 56, TAK = 56), over 296 visits, with a median follow‐up of 6 months. Correlation network analysis revealed assessment measures clustered independently by type of outcome. PhGA was centrally linked to all other outcome types, but correlations were modest (ρ = 0.12–0.32; P < 0.05). PETVAS, CRP level, and PtGA were independently associated with clinically active disease. All 4 patient‐reported outcomes strongly correlated with each other (ρ = 0.35–0.60; P < 0.0001). Patient‐reported outcomes were not correlated with PETVAS, and only PtGA correlated with CRP level (ρ = 0.16; P < 0.01). Patients whose clinical assessment changed from active disease to remission (n = 29) had a corresponding significant decrease in ESR, CRP level, and PETVAS at the remission visit. Patients whose clinical assessment changed from remission to active disease (n = 11) had a corresponding significant increase in CRP level and PtGA at the active visit.
Conclusion
Measures of disease assessment in large vessel vasculitis consist of independent, yet complementary, outcomes, supporting the need to develop composite outcome measures or a standard set of measures covering multiple types of outcomes.
Objective
To identify and validate, using computer‐driven methods, patterns of arterial disease in Takayasu arteritis (TAK) and giant cell arteritis (GCA).
Methods
Patients with TAK or GCA were ...studied from the Diagnostic and Classification Criteria for Vasculitis (DCVAS) cohort and a combined North American cohort. Case inclusion required evidence of large‐vessel involvement, defined as stenosis, occlusion, or aneurysm by angiography/ultrasonography, or increased 18F‐fluorodeoxyglucose (FDG) uptake by positron emission tomography (PET) in at least 1 of 11 specified arterial territories. K‐means cluster analysis identified groups of patients based on the pattern of arterial involvement. Cluster groups were identified in the DCVAS cohort and independently validated in the North American cohort.
Results
A total of 1,068 patients were included (DCVAS cohort: TAK = 461, GCA = 217; North American cohort: TAK = 225, GCA = 165). Six distinct clusters of patients were identified in DCVAS and validated in the North American cohort. Patients with TAK were more likely to have disease in the abdominal vasculature, bilateral disease of the subclavian and carotid arteries, or focal disease limited to the left subclavian artery than GCA (P < 0.01). Patients with GCA were more likely to have diffuse disease, involvement of bilateral axillary/subclavian arteries, or minimal disease without a definable pattern than TAK (P < 0.01). Patients with TAK were more likely to have damage by angiography, and patients with GCA were more likely to have arterial FDG uptake by PET without associated vascular damage.
Conclusion
Arterial patterns of disease highlight both shared and divergent vascular patterns between TAK and GCA and should be incorporated into classification criteria for large‐vessel vasculitis.
The globalization of trade and human movement has resulted in the accidental dispersal of thousands of alien species worldwide at an unprecedented scale. Some of these species are considered invasive ...because of their extensive spatial spread or negative impacts on native biodiversity. Explaining which alien species become invasive is a major challenge of invasion biology, and it is often assumed that invasiveness is linked to a greater ability to establish in novel climates. To test whether invasive species have expanded more into novel climates than non-invasive alien species, we quantified niche shifts of 82 ant species. Surprisingly, invasive species showed smaller niche shifts than non-invasive alien species. Independent of their invasiveness, the species with the smallest native niches and range sizes, experienced the greatest niche shifts. Overall, our results challenge the assumption that invasive species are particularly good pioneers of novel climates.
Realization of the hydrogen economy relies on effective hydrogen production, storage, and utilization. The slow kinetics of hydrogen evolution and oxidation reaction (HER/HOR) in alkaline media ...limits many practical applications involving hydrogen generation and utilization, and how to overcome this fundamental limitation remains debatable. Here we present a kinetic study of the HOR on representative catalytic systems in alkaline media. Electrochemical measurements show that the HOR rate of Pt‐Ru/C and Ru/C systems is decoupled to their hydrogen binding energy (HBE), challenging the current prevailing HBE mechanism. The alternative bifunctional mechanism is verified by combined electrochemical and in situ spectroscopic data, which provide convincing evidence for the presence of hydroxy groups on surface Ru sites in the HOR potential region and its key role in promoting the rate‐determining Volmer step. The conclusion presents important references for design and selection of HOR catalysts.
Bifunctional mechanism: Experimental evidence for hydroxy groups adsorbed onto Ru surface sites at the hydrogen oxidation reaction (HOR) potential region supports the bifunctional mechanism for the HOR kinetics of Pt‐Ru/C and Ru/C catalysts in alkaline media. The result presents important references for the design and selection of HOR catalysts.
Objective
Diagnostic assessment in giant cell arteritis (GCA) is rapidly changing as vascular imaging becomes more available. This study was undertaken to determine if clinical GCA subsets have ...distinct profiles or reflect differential diagnostic assessments.
Methods
Patients were recruited from an international cohort and divided into 4 subsets based on a temporal artery (TA) abnormality (positive TA biopsy TAB or halo sign on TA ultrasound TA‐US) and/or evidence of large vessel (LV) involvement on imaging: 1) both TA abnormality and LV involvement (TA+/LV+ GCA); 2) TA abnormality without LV involvement (TA+/LV− GCA); 3) LV involvement without TA abnormality (TA−/LV+ GCA); and 4) clinically diagnosed GCA without LV involvement or TA abnormality (TA−/LV− GCA).
Results
Nine hundred forty‐one patients with GCA were recruited from 72 international study sites. Most patients received multiple forms of diagnostic assessment, including TAB (n = 705 75%), TA‐US (n = 328 35%), and LV imaging (n = 534 57%). Assessment using TAB, TA‐US, and LV imaging confirmed the diagnosis of GCA in 66%, 79%, and 40% of cases, respectively. GCA subsets had distinct profiles independent of diagnostic assessment strategies. TA+/LV− were the most common subset (51%), with a high burden of cranial ischemia. Those in the TA−/LV− subset (26%) had a high prevalence of cranial ischemia and musculoskeletal symptoms. Patients in the TA−/LV+ subset (12%) had prevalent upper extremity vascular abnormalities and a low prevalence of vision loss, and those in the TA+/LV+ subset (11%) were older and had a high prevalence of cranial ischemia, constitutional symptoms, and elevated acute‐phase reactant levels.
Conclusion
Vascular imaging is increasingly incorporated into the diagnostic assessment of GCA and identifies clinical subsets of patients based on involvement of temporal and extracranial arteries.
Despite recent progress in developing active and durable oxygen reduction catalysts with reduced Pt content, lack of elegant bottom-up synthesis procedures with knowledge over the control of atomic ...arrangement and morphology of the Pt–alloy catalysts still hinders fuel cell commercialization. To follow a less empirical synthesis path for improved Pt-based catalysts, it is essential to correlate catalytic performance to properties that can be easily controlled and measured experimentally. Herein, using Pt–Co alloy nanoparticles (NPs) with varying atomic composition as an example, we show that the atomic distribution of Pt-based bimetallic NPs under operating conditions is strongly dependent on the initial atomic ratio by employing microscopic and in situ spectroscopic techniques. The Pt x Co/C NPs with high Co content possess a Co concentration gradient such that Co is concentrated in the core and gradually depletes in the near-surface region, whereas the Pt x Co/C NPs with low Co content possess a relatively uniform distribution of Co with low Co population in the near-surface region. Despite their different atomic structure, the oxygen reduction reaction (ORR) activity of Pt x Co/C and Pt/C NPs is linearly related to the bulk average Pt–Pt bond length (R Pt–Pt). The R Pt–Pt is further shown to contract linearly with the increase in Co/Pt composition. These linear correlations together demonstrate that (i) the improved ORR activity of Pt x Co/C NPs over pure Pt NPs originates predominantly from the compressive strain and (ii) the R Pt–Pt is a valid strain descriptor that bridges the activity and atomic composition of Pt-based bimetallic NPs.
Achieving sufficiently high combustion efficiency and stability in supersonic combustion is extremely challenging and highly dependent on the fuel-injection and mixing strategies adopted. A viable ...approach to this is the strut injector, which by inducing flow recirculation, facilitates flame stabilization in the strut-wake. In this investigation we examine in detail the flow, mixing, self-ignition and flame stabilization mechanisms of conventional and alternating-wedge injection struts. In order to analyze these, we consider NAL’s supersonic combustor, equipped with two conventional two-stage injection struts, and an alternating-wedge injection strut, in conjunction with ONERA’s vitiation air heater. Experimental results, including spontaneous flame images, wall-pressure and Planar Laser Induced Fluorescence (PLIF) images of hydroxyl (OH) are here combined with computational results based on finite-rate chemistry Large Eddy Simulation (LES) with skeletal hydrogen-air reaction mechanisms. The spontaneous flame images and the predicted flame structures for both injector-strut types agree well qualitatively, demonstrating that combustion LES captures the overall features of the experiments. Detailed comparisons between experimental data and computational results for the wall pressure and for mean and rms OH-PLIF cross-sections show acceptable agreement, indicating that the LES results can be used to further study the intrinsic features of the flame structure and the stabilization mechanism. These results indicate significant differences in flow and flame structures between both two-stage injection struts and the alternating-wedge injection strut tested. More specifically, the longitudinal vorticity introduced by the alternating-wedge injection strut increases the combustion efficiency but results in an intermittent auto-ignition phenomenon. For the two-stage injection struts combustion consists of auto-ignition pockets surrounded by self-igniting fronts embedded in a background of non-premixed flames or stirred reactors. In contrast, the alternating-wedge injection strut vigorous combustion is observed proceeding through a multi-mode (auto-ignition, non-premixed, premixed) combustion event.
Social interactions are shaped by features of the interactants, including age, emotion, sex, and familiarity. Age-specific responses to social affect are evident when an adult male rat is presented ...with a pair of unfamiliar male conspecifics, one of which is stressed via two foot shocks and the other naive to treatment. Adult test rats prefer to interact with stressed juvenile (postnatal day 30, PN30) conspecifics but avoid stressed adult (PN50) conspecifics. This pattern depends upon the insular cortex (IC), which is anatomically connected to the nucleus accumbens core (NAc). The goal of this work was to test the necessity of IC projections to NAc during social affective behavior. Here, bilateral pharmacological inhibition of the NAc with tetrodotoxin (1 μm; 0.5 μl/side) abolished the preference for stressed PN30, but did not alter interactions with PN50 conspecifics. Using a combination of retrograding tracing and c-Fos immunohistochemistry, we report that social interactions with stressed PN30 conspecifics elicit greater Fos immunoreactivity in IC → NAc neurons than interactions with naive PN30 conspecifics. Chemogenetic stimulation of IC terminals in the NAc increased social exploration with juvenile, but not adult, conspecifics, whereas chemogenetic inhibition of this tract blocked the preference to investigate stressed PN30 conspecifics, which expands upon our previous finding that optogenetic inhibition of IC projection neurons mediated approach and avoidance. These new findings suggest that outputs of IC to the NAc modulate social approach, which provides new insight to the neural circuitry underlying social decision-making.
Social decision-making underlies an animal's behavioral response to others in a range of social contexts. Previous findings indicate the insular cortex (IC) and the nucleus accumbens (NAc) play important roles in social behaviors, and human neuroimaging implicates both IC and NAc in autism and other psychiatric disorders characterized by aberrant social cognition. To test whether IC projections to the NAc are involved in social decision-making, circuit-specific chemogenetic manipulations demonstrated that the IC → NAc pathway mediates social approach toward distressed juvenile, but not adult, conspecifics. This finding is the first to implicate this circuit in rodent socioemotional behaviors and may be a neuroanatomical substrate for integration of emotion with social reward.
Disease activity in large-vessel vasculitis (LVV) is traditionally assessed by clinical and serological variables rather than vascular imaging. This study determined the effect of treatment on ...18F-fluorodeoxyglucose positron emission tomography (FDG-PET) vascular activity in relation to clinical- and serologic-based assessments.
Patients with giant cell arteritis (GCA) or Takayasu arteritis (TA) were prospectively evaluated at 6-month intervals in an observational cohort. Treatment changes were made at least 3 months before the followup visit and categorized as increased, decreased, or unchanged. Imaging (FDG-PET qualitative analysis), clinical, and serologic (erythrocyte sedimentation rate, C-reactive protein) assessments were determined at each visit and compared over interval visits.
Serial assessments were performed in 52 patients with LVV (GCA = 31; TA = 21) over 156 visits. Increased, decreased, or unchanged therapy was recorded for 36-, 23-, and 32-visit intervals, respectively. When treatment was increased, there was significant reduction in disease activity by imaging, clinical, and inflammatory markers (p ≤ 0.01 for each). When treatment was unchanged, all 3 assessments of disease activity remained similarly unchanged over 6-month intervals. When treatment was reduced, PET activity significantly worsened (p = 0.02) but clinical and serologic activity did not significantly change. Treatment of GCA with tocilizumab and of TA with tumor necrosis factor inhibitors resulted in significant improvement in imaging and clinical assessments of disease activity, but only rarely did the assessments both become normal.
In addition to clinical and serologic assessments, vascular imaging has potential to monitor disease activity in LVV and should be tested as an outcome measure in randomized clinical trials.
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