Herein, we show that the performance of mesostructured cobalt oxide electrocatalyst for oxygen evolution reaction (OER) can be significantly enhanced by coupling of silver species. Various analysis ...techniques including pair distribution function and Rietveld refinement, X‐ray absorption spectroscopy at synchrotron as well as advanced electron microscopy revealed that silver exists as metallic Ag particles and well‐dispersed Ag2O nanoclusters within the mesostructure. The benefits of this synergy are twofold for OER: highly conductive metallic Ag improves the charge transfer ability of the electrocatalysts while ultra‐small Ag2O clusters provide the centers that can uptake Fe impurities from KOH electrolyte and boost the catalytic efficiency of Co–Ag oxides. The current density of mesostructured Co3O4 at 1.7 VRHE is increased from 102 to 211 mA cm−2 with incorporation of silver spices. This work presents the dual role of silver moieties and demonstrates a simple method to increase the OER activity of Co3O4.
One stone, two birds: The twofold advantages of silver coupling with ordered mesoporous Co3O4 for OER are demonstrated. Metallic silver enhances the conductivity of the structure while Ag2O nanoclusters provide centers for Fe uptake from the KOH electrolyte and boost significantly the efficiency of the electrocatalyst.
The generation of oxidants on illuminated photocatalysts and their participation in subsequent reactions are the main basis of the widely investigated photocatalytic processes for environmental ...remediation and selective oxidation. Here, the generation and the subsequent diffusion of .OH from the illuminated TiO2 surface to the solution bulk were directly observed using a single‐molecule detection method and this molecular phenomenon could explain the different macroscopic behavior of anatase and rutile in photocatalysis. The mobile .OH is generated on anatase but not on rutile. Therefore, the photocatalytic oxidation on rutile is limited to adsorbed substrates whereas that on anatase is more facile and versatile owing to the presence of mobile .OH. The ability of anatase to generate mobile .OH is proposed as a previously unrecognized key factor that explains the common observations that anatase has higher activity than rutile for many photooxidative reactions.
Diffusing free hydroxyl radicals (.OHf) in water are responsible for the higher activity of anatase compared to rutile. A single‐molecule detection system was used to directly observe the diffusion of .OHf from the anatase surface to the bulk solution. In contrast, rutile did not create .OHf at all.
Numerous biopolymer-based functional composites have been developed for medical applications. Poly(glutamic acid) (PGA) is an amino acid biopolymer that has recently attracted attention due to its ...biocompatibility, non-immunogenicity, and biodegradability. PGA and its composites have been studied to improve their function as medical materials. This review briefly introduces chemically and microbiologically synthesized PGA. In addition, this article provides general and advanced preparation methods for various PGA-based composites, including hydrogels, nanofibers, monoliths, and nanoparticles. Furthermore, it covers recent advances in PGA-based functional composites for medical applications, such as active antimicrobial materials as well as the use of PGA composites for vaccine adjuvants, cancer therapy, medical devices, and tissue regeneration. Anticancer agent delivery and cancer immunotherapy are included in the PGA-based cancer therapy system section. Barrier membranes and stent applications are summarized within the medical devices section. Furthermore, various tissue regeneration topics are introduced, including applications in wound healing, as well as the tissue-specific regeneration of bone, cartilage, intervertebral discs, corneas, kidneys, and neurons. In summary, this is an overview of the various challenges of using PGA and the scope of emerging research.
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In situ formation of electroactive cobalt species for the oxygen evolution reaction is simply achieved by applying an anodic bias to a commercially available cobalt precursor and Nafion binder ...mixture coated on a glassy carbon electrode. This preparation does not require energy‐intensive materials preparation steps or noble metals, yet a low overpotential of 322 mV at 10.2 mA cm−2 and a high current density of more than 300 mA cm−2 at 1.7 VNHE were obtained in 1 m KOH. An operando electrochemical Raman spectroscopy study confirmed the formation of cobalt oxyhydroxide species and the iron stimulated the equilibrium state between Co3+ and Co4+. The iron present in the alkali electrolyte or ink solution effectively activated the cobalt species, and most of the first row transition metals could also enhance the catalytic performance. The concept presented here is one of the simplest strategies for preparing highly active electrocatalysts and is very flexible for the replacement of cobalt by other transition metals.
Simplest is best: Electroactive cobalt species for the oxygen evolution reaction can be prepared simply by applying an anodic bias to a mixture of a commercially available cobalt precursor and Nafion binder coated on a glassy carbon electrode. Iron dopants effectively activate the cobalt species, and most of the first row transition metals could also enhance the catalytic performance.
Abstract
Ag(I) is commonly employed as an electron scavenger to promote water oxidation. In addition to its straightforward role as an electron acceptor, Ag(I) can also capture holes to generate the ...high-valent silver species. Herein, we demonstrate photoelectrocatalytic (PEC) water oxidation and concurrent dioxygen evolution by the silver redox cycle where Ag(I) acts as a hole-transfer mediator. Ag(I) enhances the PEC performance of WO
3
electrodes at 1.23 V vs. RHE with increasing O
2
evolution, while forming Ag(II) complexes (Ag
II
NO
3
+
). Upon turning off both light and potential bias, the photocurrent immediately drops to zero, whereas O
2
evolution continues over ~10 h with gradual bleaching of the colored complexes. This phenomenon is observed neither in the Ag(I)-free PEC reactions nor in the photocatalytic (i.e., bias-free) reactions with Ag(I). This study finds that the role of Ag(I) is not limited as an electron scavenger and calls for more thorough studies on the effect of Ag(I).
Ultrahigh-efficiency photoelectrochemical water oxidation using modified hematite (α-Fe2O3) nanorod arrays is reported. The hematite nanorod arrays are synthesized using chemical bath deposition and ...further modified by hydrogen treatment, loading of a ~ 3.5-nm-thick TiO2 overlayer, and deposition of a cobalt phosphate (CoPi) catalyst. Although each modification method is well known, an elaborate optimization of the combined modification methods achieves a stable photocurrent density of ~ 6mAcm−2 at 1.23V vs. RHE over 100h under AM 1.5G irradiation (100mWcm−2) with the stoichiometric O2 and H2 evolutions at ~ 95% of Faradaic efficiency. To the best of our knowledge, this is the highest photocurrent density obtained using a hematite-based photoanode, and such long-term durability coupled with this level of efficiency has been rarely reported. The modified-hematite photoanodes are thoroughly characterized using various spectroscopic and electrochemical techniques. While the hydrogen treatment enhances the electrical conductivity, the ultrathin TiO2 overlayer reduces the surface charge recombination and effectively preserved the integrity of the hydrogen-treated hematite electrode.
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•Hematite nanorod arrays doped with hydrogen and coated with an ultrathin TiO2 layer are synthesized.•An optimized hematite exhibits unprecedented photocurrents of ~ 6mAcm−2 at 1.23V over 100h.•O2 is linearly produced from water with a current efficiency of 100% without deactivation for 100h.•A stoichiometric amount of H2 was simultaneously produced.
The levelized cost of electricity (LCOE) of a commercial scale photovoltaics (PV) system is quantitatively investigated. The impact of the system and financial parameters, the installed system cost, ...solar insolation, system lifetime, system derate losses, module cost, module efficiency, balance of system (BOS) cost, inflation, discount rate, and loan rate, are quantitatively calculated using the System Advisor Model (SAM) from the National Renewable Energy Laboratory (NREL). 3D contour plots are generated to assess the impact of the key system and financial parameters on the LCOE. Calculations show that an installed system cost of 2.8, 2.3, and 2.1$/W can provide an LCOE of ~10¢/kWh (average price of electricity in the US) in Phoenix, Atlanta, and Boston, respectively, for a 30 years system lifetime, 20% system derate losses without investment tax credit (ITC). In addition, contour plots are generated to show what happens to the LCOE if the above parameters change. The study uses reasonable inputs for the current (2015) commercial scale PV system in the US.
•LCOE calculations of commercial scale PV system.•Grid parity near future.•Sensitivity of system parameters on LCOE.•SunShot initiative, 1.3$/W by 2020.
We evaluated the performance of new high‐throughput digital lateral flow immunoassays (LFIAs) detecting influenza antigens and compared them with those of the widely used digital LFIA and the rapid ...nucleic acid amplification test (NAAT). We tested 199 clinical nasopharyngeal (nasal) swab samples using three LFIA tests (BD Veritor Plus, STANDARD F Influenza A/B FIA, and ichroma TRIAS) and the rapid NAAT (ID NOW Influenza A & B2). Agreements and clinical performances (sensitivity and specificity) were evaluated based on the results of reverse transcriptase‐polymerase chain reaction (RT‐PCR) and verification panel. The agreement of each test with RT‐PCR was moderate to almost perfect. The sensitivity of ID NOW was significantly higher than that of LFIAs (P = .0005, .0044, and .0026 for influenza A and P = .0044, .0026, and .0044 for influenza B, respectively). The specificities were not significantly different between the four tests (P > .05). However, the reference panel suggests that ichroma TRIAS test is more sensitive than the other two LFIA tests. All three LFIA assays performed similarly with no false positives against influenza A. For influenza B, ichroma TRIAS had 2 of 166 false positives whereas there were no false positives for the other two LFIA tests. Influenza antigen digital LFIAs have advantages in terms of the workflow when simultaneous tests are required. Rapid NAAT has higher sensitivity, while new antigen LFIAs are efficient and high‐throughput. It is recommended that users select appropriate methods and algorithms according to the number of specimens and laboratory conditions in each clinical laboratory.
Highlights
We evaluated the performance of new high‐throughput digital lateral flow immunoassays (LFIAs) detecting influenza antigens, and compared with those of the widely used digital LFIA and the rapid nucleic acid amplification test (NAAT).
All three LFIA assays performed similarly against influenza A and B.
Rapid NAAT has higher sensitivity, while new antigen LFIAs are efficient and high‐throughput.
Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 ...(LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine binding. The phosphorylated LARS1 showed decreased leucine binding, which may inhibit protein synthesis and help save energy. Leucine that is not used for anabolic processes may be available for catabolic pathway energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival under glucose deprivation. Thus, depending on glucose availability, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.
To identify emergency department triage accuracy using the Korean Triage and Acuity Scale (KTAS) and evaluate the causes of mistriage.
This cross-sectional retrospective study was based on 1267 ...systematically selected records of adult patients admitted to two emergency departments between October 2016 and September 2017. Twenty-four variables were assessed, including chief complaints, vital signs according to the initial nursing records, and clinical outcomes. Three triage experts, a certified emergency nurse, a KTAS provider and instructor, and a nurse recommended based on excellent emergency department experience and competence determined the true KTAS. Triage accuracy was evaluated by inter-rater agreement between the expert and emergency nurse KTAS scores. The comments of the experts were analyzed to evaluate the cause of triage error. An independent sample t-test was conducted to compare the number of patient visits per hour in terms of the accuracy and inaccuracy of triage.
Inter-rater reliability between the emergency nurse and the true KTAS score was weighted kappa = .83 and Pearson's r = .88 (p < .001). Of 1267 records, 186 (14.7%) showed some disagreement (under triage = 131, over triage = 55). Causes of mistriage included: error applying the numerical rating scale (n = 64) and misjudgment of the physical symptoms associated with the chief complaint (n = 47). There was no statistically significant difference in the number of patient visits per hour for accurate and inaccurate triage (t = -0.77, p = .442).
There was highly agreement between the KTAS scores determined by emergency nurses and those determined by experts. The main cause of mistriage was misapplication of the pain scale to the KTAS algorithm.
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