The electrochemical synthesis of chemicals and fuel feedstocks has been demonstrated to be a sustainable and “green” alternative to traditional chemical engineering, where oxygen evolution reaction ...(OER) plays a vital role in coupling with various cathodic reactions. While tremendous attention, involving both research and review topics, has been focused on pushing the limit of OER catalysts’ activity, the long-term stability of OER catalysts, which may play an even more important role in large-scale electrolysis industrialization, has been much less emphasized. Until this point, few systematic strategies for developing OER catalysts with industrially relevant durability have been reported. In this review, critical mechanisms that could influence OER stability are summarized, including surface reconstruction, lattice oxygen evolution, and the dissolution-redeposition process of catalysts. Moreover, to bridge the gap between lab-scale OER tests and large-scale electrocatalysis applications, stability considerations in electrolyzer design for long-term operation are also discussed in detail. This review provides catalyst and reactor design principles for overcoming OER stability challenges and will focus more attention from the field on the great importance of OER stability as well as future large-scale electrocatalysis applications.
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Recently, clean energy conversion through electrocatalysis is evolving rapidly as a promising alternative to fossil-fuel energy systems. However, electrolyzers have always suffered from long-term stability challenges, especially for the anodic oxygen evolution reaction catalysts. So far, other than high-cost noble-metal catalysts such as IrO2, no catalysts with industrially relevant stability for oxygen evolution process in acidic and neutral conditions have been demonstrated. Thus, mechanisms that lead to catalytic instability require further investigation and deep understanding to guide future catalyst design.
In order to explore both the origins of and solutions to the stability challenges, this review provides a comprehensive overview and analysis on mechanistic studies of OER catalytic stability. Surface reconstruction of catalysts under oxidation potential during oxygen evolution is one of the causes of catalyst degradation. In addition, lattice oxygen can sometimes participate in the reaction pathway and induce structural instability of catalysts. In addition, redeposition of dissolved ions onto the catalyst surface is a process that gains less attention but can greatly influence the catalytic stability. Besides the catalyst consideration, critical elements of electrolyzers are also discussed in this review to provide insights in electrolysis operation under more realistic conditions. Based on the studies summarized in this article, we also provide potential strategies to design stable OER catalysts. By appropriately tuning the components, structures, dissolution, and redeposition rates of catalysts, we believe that the development of catalysts with long-term stability for oxygen evolution reaction can be achieved in the near future.
Oxygen evolution reaction (OER) plays a vital role in clean energy conversion through electrochemical synthesis of chemicals and fuel feedstocks. However, OER catalysts have always suffered from long-term stability challenges. This review timely summarizes critical reaction mechanisms that could influence OER stability, discusses stability considerations for reactor designs, and proposes future perspectives and potential strategies for designing stable OER catalysts to overcome these challenges.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Electrochemical oxygen reduction to hydrogen peroxide (H
O
) in acidic media, especially in proton exchange membrane (PEM) electrode assembly reactors, suffers from low selectivity and the lack of ...low-cost catalysts. Here we present a cation-regulated interfacial engineering approach to promote the H
O
selectivity (over 80%) under industrial-relevant generation rates (over 400 mA cm
) in strong acidic media using just carbon black catalyst and a small number of alkali metal cations, representing a 25-fold improvement compared to that without cation additives. Our density functional theory simulation suggests a "shielding effect" of alkali metal cations which squeeze away the catalyst/electrolyte interfacial protons and thus prevent further reduction of generated H
O
to water. A double-PEM solid electrolyte reactor was further developed to realize a continuous, selective (∼90%) and stable (over 500 hours) generation of H
O
via implementing this cation effect for practical applications.
BACKGROUND:Giant cell tumor (GCT) of bone is a rare, benign, aggressive bone tumor with an unusual capacity to metastasize to the lung. It was the goal of this study to identify patient and ...treatment-specific variables associated with the development of pulmonary metastases of GCT of bone.
METHODS:From 1980 to 2009, 291 patients with benign GCT of bone were treated at our institution, and 167 were followed for at least two years. Eleven (6.6%) of these 167 patients developed biopsy-confirmed pulmonary metastasis. All patients were evaluated relative to nine patient, disease, and treatment-specific variables.
RESULTS:We identified four properties of benign GCT of bone associated with an increased risk of metastasis on univariate analysisage at diagnosis, axial location of the primary GCT, primary Enneking stage-3 disease, and local recurrence. Multivariate analysis showed local recurrence to be an independent risk factor for pulmonary metastasis (adjusted odds ratio, 7.42).
CONCLUSIONS:There is an increased risk of pulmonary metastasis of GCT of bone in patients who are younger, present with Enneking stage-3 disease, develop local recurrence, and/or present with axial disease. The mode of treatment was not found to be associated with the development of pulmonary metastasis.
LEVEL OF EVIDENCE:Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
The two-electron oxygen reduction reaction (2e–-ORR) can be exploited for green production of hydrogen peroxide (H2O2), but it still suffers from low selectivity in an acidic electrolyte when using ...non-noble metal catalysts. Here, inspired by biology, we demonstrate a strategy that exploits the micellization of surfactant molecules to promote the H2O2 selectivity of a low-cost carbon black catalyst in strong acid electrolytes. The surfactants near the electrode surface increase the oxygen solubility and transportation, and they provide a shielding effect that displaces protons from the electric double layer (EDL). Compared with the case of a pure acidic electrolyte, we find that, when a small number of surfactant molecules were added to the acid, the H2O2 Faradaic efficiency (FE) was improved from 12% to 95% H2O2 under 200 mA cm–2, suggesting an 8-fold improvement. Our in situ surface enhanced Raman spectroscopy (SERS) and optical microscopy (OM) studies suggest that, while the added surfactant reduces the electrode’s hydrophobicity, its micelle formation could promote the O2 gas transport and its hydrophobic tail could displace local protons under applied negative potentials during catalysis, which are responsible for the improved H2O2 selectivity in strong acids.
Background A recent study found that NuvaRing (a vaginal contraceptive ring containing 15 µg ethinyl estradiol and 120 µg etonogestrel) has 2.5 times increased relative risk of thrombotic stroke ...compared to nonuse. Objective We studied a case series of 19 such patients as well as prior published case reports to clarify clinical, radiological, and prognostic features. Methods Medical records and imaging for 18 cases were initially systematically reviewed for consultation in a class action lawsuit. One case was seen personally outside of litigation. All 19 cases were entered into a database detailing clinical, radiological, and prognostic features as well as other potential risk factors. A literature search identified 8 additional cases. Results Average age at stroke was 31.7 ± 9.8 years; average duration of NuvaRing use prior to stroke was 11.2 months. Arterial stroke occurred in 10 of 19 (52%); 1 of 10 (10%) was hemorrhagic. Venous sinus thrombosis was present in 11 of 19 (58%) on initial imaging; 6 of 11 (54%) were hemorrhagic. The most common presenting symptom was headache (7 of 19 37%) and motor weakness (7 of 19 37%). A hypercoagulable condition was present in 3 of 19 (16%); 3 of 19 (16%) had history of hypercoagulable disease in a first-degree relative. Mortality was .5%; 8 of 19 (42%) fully recovered and 3 of 19 (15%) were discharged to rehabilitation. Conclusions In this largest case series of NuvaRing-associated stroke to date, approximately half of the strokes are venous and half are arterial. Stroke typically occurred within the first year of use, and as soon as 2 weeks after NuvaRing initiation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This study examines the diffusion coefficients of cuprous and cupric ions in aqueous solutions containing 4–6 mol·dm–3 bromide ion. Under these conditions, the majority of the Cu2+ species is the ...complex CuBr4 –2, and the majority of Cu+ species is the complex CuBr3 –2. Diffusion coefficients were obtained for temperatures ranging from 298 to 334 K via a rotating disk electrode and the Levich relationship. Diffusion coefficients for the cuprous bromide complex were found to be between 11.9 and 19.1 × 10–6 cm2·s–1. Diffusion coefficients for the cupric bromide complex ranged between 4.5 and 12.0 × 10–6 cm2·s–1. Confidence intervals were calculated with reasonable uncertainties. The diffusion coefficients were found to be in good agreement with literature values of cuprous and cupric chloride complexes.
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IJS, KILJ, NUK, PNG, UL, UM
The Challenges of a Vertical Evacuation Drill Salway, Richard J. (RJ); Adler, Zachary; Williams, Trenika ...
Prehospital and disaster medicine,
02/2019, Volume:
34, Issue:
1
Journal Article
Peer reviewed
IntroductionRecent natural and infrastructural disasters, such as Hurricanes Sandy (2012) and Katrina (2005) and the Northeastern power outage of 2003, have emphasized the need for hospital staff to ...be trained in disaster management and response. Even an internal hospital disaster may require the safe and efficient evacuation and transfer of patients with varying medical conditions and complications. A notably susceptible population is renal transplant patients, including those with post-transplant complications.HypothesisThis descriptive study evaluated staff performance of a vertical evacuation drill of renal transplant patients at State University of New York (SUNY) Downstate Medical Center - University Hospital Brooklyn (UHB; Brooklyn, New York USA).
Thirteen standardized patients, 12 of whom received a renal transplant, with varying medical histories, ambulatory ability, and mental status were vertically evacuated by the transplant staff from the eighth floor to the ambulance entrance on the ground floor. Non-ambulatory patients were transported on portable evacuation sleds.
All patients were evacuated successfully within 3.5 hours. On a post-drill evaluation form, drill participants self-reported largely positive results concerning their own role in the drill and the evacuation drill itself. Drill evaluators observed very different results, including staff reticence, poor training retention, and lack of leadership.
Despite encouraging post-drill evaluation results from the participants, the evacuation drill highlighted several immediate deficiencies. It also demonstrated a significant discrepancy in performance perception between the drill participants and the drill evaluators.Salway RJ, Adler Z, Williams T, Nwoke F, Roblin P, Arquilla B. The challenges of a vertical evacuation drill.
