Insight into Defect Engineering of Atomically Dispersed Iron Electrocatalysts for High-Performance Proton Exchange Membrane Fuel Cell

Atomically dispersed and nitrogen coordinated iron catalysts (Fe-NCs) demonstrate potential as alternatives to platinum-group metal (PGM) catalysts in oxygen reduction reaction (ORR). However, in the context of practical proton exchange membrane fuel cell (PEMFC) applications, the membrane electrode assembly (MEA) performances of Fe-NCs remain unsatisfactory. Herein, improved MEA performance is achieved by tuning the local environment of the Fe-NC catalysts through defect engineering. Zeolitic imidazolate framework (ZIF)-derived nitrogen-doped carbon with additional CO2 activation is employed to construct atomically dispersed iron sites with a controlled defect number. The Fe-NC species with the optimal number of defect sites exhibit excellent ORR performance with a high half-wave potential of 0.83 V in 0.5 M H2 SO4 . Variation in the number of defects allows for fine-tuning of the reaction intermediate binding energies by changing the contribution of the Fe d-orbitals, thereby optimizing the ORR activity. The MEA based on a defect-engineered Fe-NC catalyst is found to exhibit a remarkable peak power density of 1.1 W cm-2 in an H2 /O2 fuel cell, and 0.67 W cm-2  in an H2 /air fuel cell, rendering it one of the most active atomically dispersed catalyst materials at the MEA level.

Transition Metal Ion Doping on ZIF-8 Enhances the Electrochemical CO2 Reduction Reaction

The electrochemical reduction of CO2  to diverse value-added chemicals is a unique, environmentally friendly approach for curbing greenhouse gas emissions while addressing sluggish catalytic activity and low Faradaic efficiency (FE) of electrocatalysts. Here, zeolite-imidazolate-frameworks-8 (ZIF-8) containing various transition metal ions-Ni, Fe, and Cu-at varying concentrations upon doping are fabricated for the electrocatalytic CO2 reduction reaction (CO2 RR) to carbon monoxide (CO) without further processing. Atom coordination environments and theoretical electrocatalytic performance are scrutinized via X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations. Upon optimized Cu doping on ZIF-8, Cu0.5 Zn0.5 /ZIF-8 achieves a high partial current density of 11.57 mA cm-2 and maximum FE for CO of 88.5% at -1.0 V (versus RHE) with a stable catalytic activity over 6 h. Furthermore, the electron-rich sp2 C atom facilitates COOH* promotion after Cu doping of ZIF-8, leading to a local effect between the zinc-nitrogen (Zn-N4 ) and copper-nitrogen (Cu-N4 ) moieties. Additionally, the advanced CO2 RR pathway is illustrated from various perspectives, including the pre-H-covered state under the CO2 RR. The findings expand the pool of efficient metal-organic framework (MOF)-based CO2 RR catalysts, deeming them viable alternatives to conventional catalysts.

Development of a COX-2-Selective Fluorescent Probe for the Observation of Early Intervertebral Disc Degeneration

Cyclooxygenase-2 (COX-2) is a biomolecule known to be overexpressed in inflammation. Therefore, it has been considered a diagnostically useful marker in numerous studies. In this study, we attempted to assess the correlation between COX-2 expression and the severity of intervertebral disc (IVD) degeneration using a COX-2-targeting fluorescent molecular compound that had not been extensively studied. This compound, indomethacin-adopted benzothiazole-pyranocarbazole (IBPC1), was synthesized by introducing indomethacin—a compound with known selectivity for COX-2—into a phosphor with a benzothiazole-pyranocarbazole structure. IBPC1 exhibited relatively high fluorescence intensity in cells pretreated with lipopolysaccharide, which induces inflammation. Furthermore, we observed significantly higher fluorescence in tissues with artificially damaged discs (modeling IVD degeneration) compared to normal disc tissues. These findings indicate that IBPC1 can meaningfully contribute to the study of the mechanism of IVD degeneration in living cells and tissues and to the development of therapeutic agents.

Facet-Defined Strain-Free Spinel Oxide for Oxygen Reduction

Exposing facet and surface strain are critical factors affecting catalytic performance but unraveling the composition-dependent activity on specific facets under strain-controlled environment is still challenging due to the synthetic difficulties. Herein, we achieved a (001) facet-defined Co-Mn spinel oxide surface with different surface compositions using epitaxial growth on Co₃O₄ nanocube template. We adopted composition gradient synthesis to relieve the strain layer by layer, minimizing the surface strain effect on catalytic activity. In this system, experimental and calculational analyses of model oxygen reduction reaction (ORR) activity reveals a volcano-like trend with Mn/Co ratios because of an adequate charge transfer from octahedral-Mn to neighboring Co. Co_0.5Mn_0.5 as an optimized Mn/Co ratio exhibits both outstanding ORR activity (0.894 V vs RHE in 1 M KOH) and stability (2% activity loss against chronoamperometry). By controlling facet and strain, this study provides a well-defined platform for investigating composition-structure-activity relationships in electrocatalytic processes.

Structural Insights into Multi-Metal Spinel Oxide Nanoparticles for Boosting Oxygen Reduction Electrocatalysis

Multi-metal oxide (MMO) materials have significant potential to facilitate various demanding reactions by providing additional degrees of freedom in catalyst design. However, a fundamental understanding of the (electro)catalytic activity of MMOs is limited because of the intrinsic complexity of their multi-element nature. Additional complexities arise when MMO catalysts have crystalline structures with two different metal site occupancies, such as the spinel structure, which makes it more challenging to investigate the origin of the (electro)catalytic activity of MMOs. Here, uniform-sized multi-metal spinel oxide nanoparticles composed of Mn, Co, and Fe as model MMO electrocatalysts are synthesized and the contributions of each element to the structural flexibility of the spinel oxides are systematically studied, which boosts the electrocatalytic oxygen reduction reaction (ORR) activity. Detailed crystal and electronic structure characterizations combined with electrochemical and computational studies reveal that the incorporation of Co not only increases the preferential octahedral site occupancy, but also modifies the electronic state of the ORR-active Mn site to enhance the intrinsic ORR activity. As a result, nanoparticles of the optimized catalyst, Co_0.25 Mn_0.75 Fe_2.0 -MMO, exhibit a half-wave potential of 0.904 V (versus RHE) and mass activity of 46.9 A g_oxide ^-1 (at 0.9 V versus RHE) with promising stability.

USING GUESSING GAME TO INCREASE COMPLICATION AWARENESS OF PATIENTS WITH NEWLY DIAGNOSED TYPE 2 DIABETES

Background

Prevention of complications is widely considered as the main aim of diabetes control. And diabetes education is the cornerstone for type 2 diabetes (T2D) management. However, traditional lecture-based diabetes patient education activities have small and short-lasting efficacy. Therefore, technology-based initiatives for diabetes patient education are urgently required.

Objective

To evaluate Guessing, a popular game, as tool in increasing complication awareness of patients with newly diagnosed T2D during diabetes care.

Patients and Methods

In a cohort study, 103 patients were split into Guessing Game group and control group. The opinions of patients and educators in Guessing Game group were surveyed. Patient performance was evaluated by test scores and the attendance to diabetes complication screening clinic.

Results

A majority of patients and all educators believed that Guessing Game enhanced complication awareness. Educatees achieved higher total scores and test scores in "Fill in the Gaps" (one of 2 types of test item), more actively attended complication screening clinic, after using Guessing Game as an education tool.

Conclusion

Guessing Game is an attractive and effective educational intervention to increase complication awareness of T2D patients.

Retroanastomotic hernia after gastrojejunostomy: US and CT findings with an emphasis on the whirl sign

BACKGROUND

We reviewed ultrasound (US) and computed tomographic (CT) findings of retroanastomotic hernia and established whether such findings are characteristic of retroanastomotic hernia in patients who have undergone gastrojejunostomy.

METHODS

During a recent 10-year period, we encountered 13 consecutive cases of retroanastomotic hernia. Of the patients involved, 11 underwent US, 10 underwent CT, and three underwent small bowel followthrough imaging. The US and CT scans were retrospectively reviewed to determine abnormal findings. Surgical proof was available in all cases.

RESULTS

The efferent loop was herniated through the defect created behind the anastomosis in 10 cases, the efferent and afferent loops in two cases, and the afferent loop in one case. Retroanastomotic hernia was prospectively suggested in 12 of these 13 cases. Among the 10 cases of efferent loop herniation, US and CT signs of retroanastomotic hernia included whirling of mesenteric vessels, jejunal loops, and mesentery in the periumbilical abdomen (10 of 10); mural thickening of herniated bowel loops (six of 10); dilatation of herniated bowel loops (four of 10); decreased peristalsis of herniated bowel loops on US (three of nine); and decreased contrast enhancement of herniated bowel loops on CT (one of seven). In one case, US and CT signs of retroanastomotic hernia of the afferent loop included its dilatation and whirling of a short length of afferent loop behind the anastomosis. In two cases, US and CT signs of retroanastomotic hernia of the afferent and efferent loops included findings of afferent and efferent loop herniations. Three of 13 cases had reversible bowel ischemia, and one had bowel necrosis.

CONCLUSION

Retroanastomotic hernia is an important condition, and the US and CT findings we have described might suggest its diagnosis.

Action of Sosiho-Tang on systemic and local anaphylaxis by anal administration

The herbal formulation Soshiho-Tang (SS-Tang) has been used against allergic disease for generations, and still occupies an important place in traditional medicine in Korea. Previously, we reported that SS-Tang potently inhibited mast cell- mediated anaphylaxis when orally administered. In this study, we investigated the effect of SS-Tang by anal administration in anaphylaxis responses. SS-Tang dose-dependently inhibited compound 48/80-induced systemic anaphylaxis with doses of 10(-4) to 1 g/kg 1 h before anally administered. Of special note, SS-Tang inhibited systemic anaphylaxis completely with a dose of 1 g/kg. SS-Tang reduced plasma histamine levels induced by compound 48/80 significantly. However, the mortality was 100% when SS-Tang was administered after compound 48/80 treatment. SS-Tang (10(-1) g/kg) also inhibited passive cutaneous anaphylaxis activated by anti-dinitrophenyl IgE antibody by 30.9%. These results provide evidence that anal therapy of SS-Tang may be beneficial in the treatment of systemic and local anaphylaxis.