Facile Synthesis of N-Doped Metal-Free Catalysts for Oxygen Reduction Reaction via a Self-Sacrificed Template Method Using Zinc Amino-Acid Complex.

Precisely controlled heteroatom-doped metal-free carbon catalysts are highly desirable for use in various renewable energy conversion and storage devices. Herein, we report a nitrogen-doped metal-free carbon catalyst for the oxygen reduction reaction (ORR) using a facile and cost-effective synthetic method. The obtained catalysts (NC-1100) were synthesized in two steps via an amino-acid complex coating and high-temperature carbonization. The various physical characteristics revealed that NC-1100 has a unique morphology, a controlled nitrogen bonding configuration, and a uniform pore distribution. The resulting catalyst shows excellent catalytic performance toward direct 4-electron oxygen reduction reaction (ORR) in an alkaline electrolyte, with a high onset potential of 0.95 V versus RHE and limiting current density (4.5 mA cm-2). Furthermore, the developed catalysts showed superior long-term operating stability and methanol durability compared to those of commercial Pt/C. This study provides a promising guideline for the development of next-generation electrocatalysts for fuel cells and wider applications.

Facile and Cost-effective Synthesis of CoP@N-doped Carbon with High Catalytic Performance for Electrochemical Hydrogen Evolution Reaction.

The manufacture of efficient and low-cost hydrogen evolution reaction (HER) catalysts is regarded as a critical solution to achieve carbon neutrality. Herein, we developed an economical method to synthesize a CoP-anchored N-doped carbon catalyst via one-step pyrolysis using inexpensive starting materials (cobalt ion salt, phytic acid, and glycine). The size of the CoP nanoparticles was controlled by adjusting the Co/P ratio of the catalysts. Nanoscale CoP particles with adequate exposure to active sites were uniformly anchored on the surface of the conductive nitrogen-doped carbon substrate, ensuring the rapid transfer of electrons and species. When Co/P=0.89, the as-made catalyst exhibited outstanding HER activity, with an extraordinarily low overpotential of 202 mV at 10 mA cm-2 and long-term stability.

A zeolite templating method for fabricating edge site-enriched N-doped carbon materials.

N-doped carbon materials have attracted considerable attention as highly functional materials because nitrogen doping distorts the carbon lattice, changes the charge density, and introduces additional defects. Among various positions of N atoms in N-doped carbon compounds, pyridinic-N, pyrrolic-N, and valley-N, which are doped at edge sites, exhibit specific electrocatalytic activities during the oxygen reduction reaction (ORR). However, it is difficult to selectively introduce these N atoms into a carbon matrix because the synthesis procedure typically includes high-temperature heat treatment. In this study, we applied a zeolite templating method to synthesize edge site-rich N-doped carbon materials. The sample fabricated using a zeolite template possessed high concentrations of pyridinic-N and valley-N atoms, demonstrating a significantly higher ORR catalytic activity than the sample synthesized without a zeolite template. Additional experiments conducted using various zeolites confirmed the positive effect of N-doped carbons on the ORR catalytic performance. This work demonstrated that the zeolite templating method not only increased the specific surface area and the number of active sites but also selectively created edge sites and improved the quality of the active sites.

Emphysematous gastritis associated with ileus due to fecal impaction.

Background: Gastric emphysema and emphysematous gastritis (EG) are rare diseases involving air being introduced into the stomach wall. Emphysematous gastritis is an infectious disease with a high fatality rate. Case presentation: An 83-year-old woman had recovered from septic shock, however, an antibiotic-refractory inflammatory response remained. She was diagnosed with pseudogout and administered a non-steroidal anti-inflammatory drug. However, abdominal pain, prominent abdominal distension, and strawberry milk-like gastric juice were recognized. Computed tomography showed ileus due to fecal impaction and GE. The results of culture of the gastric juice were positive (Pseudomonas aeruginosa and Enterococcus faecalis). Disimpaction, fasting management, and antibacterial treatments resulted in the recovery of her symptoms. Conclusion: This is the first case in which ileus associated with fecal impaction caused EG. The present case highlights the importance of promoting regular bowel movements.

Inhibition of ammonium assimilation restores elongation of seminal rice roots repressed by high levels of exogenous ammonium.

Elongation of seminal and lateral roots of rice seedlings was markedly inhibited by high ammonium levels in growth medium. However, high exogenous nitrate concentrations had little inhibitory effect on root growth. The objective of this study was to elucidate the relationship between inhibition of rice root growth induced by high ammonium conditions and ammonium assimilation in the seedlings. Activity of glutamine synthetase (GS) was kept at a low level in the seminal roots of the seedlings grown under high nitrate levels. In contrast, high ammonium levels significantly enhanced the GS activity in the roots, so that Gln abundantly accumulated in the shoots. These results indicate that ammonium assimilation may be activated in the seminal roots under high ammonium conditions. Application of methionine sulfoximine (MSO), an inhibitor of GS, relieved the repression of the seminal root elongation induced by high ammonium concentrations. However, the elongation of lateral roots remained inhibited even under the same condition. Furthermore, MSO drastically increased ammonium level and remarkably decreased Gln level in the shoots grown under high ammonium conditions. These results show that, for rice seedlings, an assimilatory product of ammonium, and not ammonium itself, may serve as an endogenous indicator of the nitrogen status involved in the inhibition of seminal root elongation induced by high levels of exogenous ammonium.

Evaluation of time-course changes of gingival crevicular fluid glucose levels in diabetics.

A minute volume such as a few hundred nano-litres of gingival crevicular fluid (GCF) will evaporate within one minute at room temperature after collection. In order to investigate the feasibility of a method for noninvasive blood glucose measurement using this fluid, a fabricated GCF-collecting device, and the time-course changes of blood and GCF glucose levels in diabetics were evaluated. As a result of improvement in the GCF-collecting device such that the color of a filter paper changed from white to black upon collection of the sample, the completion of the collecting procedure could be visually confirmed. Using this device, we succeeded in collecting 200 nl of GCF within 30 s, despite the fact that GCF is usually secreted at a rate between 2 and 3 microl per tooth per hour. This method could be applicable for collecting small volume of other biological fluids. The time-course changes of blood and GCF glucose levels in ten type 2 diabetic subjects were examined, the correlation coefficient, R, between both glucose levels was 0.878. The result proved to be similar to that for normal healthy subjects in a previous study. A significant time difference between the two glucose levels was not observed. In diabetes period of 4.8 +/- 1.7 years, the influence of the disease on the GCF glucose level was minimal. Furthermore, from the ROC curve analysis, both sensitivity and specificity showed favorable results. It was suggested that the measurement of GCF glucose levels was a promising screening method for diabetics.