Improving Fuel Cell Performance of FeN-Based Catalysts by Introducing Graphitic Microdomains in the Carbon Matrix.

Breaking the known activity-stability trade-off is essential for the broad implementation of Fe-N-C catalysts in fuel cells. Here, we report the development of an atomically dispersed Fe-N-C catalyst with highly active FeN sites on carbon support with dispersed graphitic microdomains (FeN-Gmd), which were generated during the FeC-catalyzed graphitization. The introduction of graphitic microdomain makes the FeN-Gmd exhibit outstanding oxygen reduction reaction activity when used as a cathode catalyst in practical fuel cells, with impressive peak power densities of 1.

Improving the Cold-Start Performance of Proton Exchange Membrane Fuel Cells via Precision Engineering of Key Materials.

Proton exchange membrane fuel cells (PEMFCs) have emerged as important zero-emission power sources due to their efficiency and eco-friendly characteristics. A critical feature required for their widespread adoption is the performance of low-temperature cold start. However, at subzero degrees Celsius, the freezing of the produced water can hinder or even lead to failure of the fuel cell start-up process.

How is a turbidite actually deposited?

The deposition of a classic turbidite by a surge-type turbidity current, as envisaged by conceptual models, is widely considered a discrete event of continuous sediment accumulation at a falling rate by the gradually waning density flow. Here, we demonstrate, on the basis of a high-resolution advanced numerical CFD (computational fluid dynamics) simulation and rock-record examples, that the depositional event in reality involves many brief episodes of nondeposition. The reason is inherent hydraulic fluctuations of turbidity current energy driven by interfacial Kelvin-Helmholtz waves.

High Concentrations of Ketocarotenoids in Hepatic Mitochondria of Haemorhous mexicanus.

Vertebrates cannot synthesize carotenoid pigments de novo, so to produce carotenoid-based coloration they must ingest carotenoids. Most songbirds that deposit red carotenoids in feathers, bills, eyes, or skin ingest only yellow or orange dietary pigments, which they oxidize to red pigments via a ketolation reaction. It has been hypothesized that carotenoid ketolation occurs in the liver of vertebrates, but this hypothesis remains to be confirmed.

Copper-catalyzed C-N bond formation/rearrangement sequence: synthesis of 4H-3,1-benzoxazin-4-ones.

A facile and efficient copper-catalyzed method for the synthesis of 4H-3,1-benzoxazin-4-one derivatives has been developed. This procedure is based on a tandem intramolecular C-N coupling/rearrangement process. This method would provide a new and useful strategy for construction of N-heterocycles.

Palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides via tert-butyl isocyanide insertion.

A simple and efficient palladium-catalyzed carbonylative Sonogashira coupling via tert-butyl isocyanide insertion has been developed, which demonstrates the utility of isocyanides in intermolecular C-C bond construction. This methodology provides a novel pathway for the synthesis of alkynyl imines which can undergo simple silica gel catalyzed hydrolysis to afford alkynones. The approach is tolerant of a wide range of substrates and applicable to library synthesis.

Palladium-catalyzed synthesis of isocoumarins and phthalides via tert-butyl isocyanide insertion.

A novel and highly efficient strategy for the synthesis of isocoumarins and phthalides through a palladium(0)-catalyzed reaction incorporating tert-butyl isocyanide has been developed. This process, providing one of the simplest methods for the synthesis of this class of valuable lactones, involves two steps including cyclization reaction and simple acid hydrolysis. The methodology is tolerant of a wide range of substrates and applicable to library synthesis.

Synthesis of 3-substituted isocoumarins via a cascade intramolecular Ullmann-type coupling-rearrangement process.

A simple and highly efficient strategy for the synthesis of 3-substituted isocoumarins through a copper(I)-catalyzed reaction of 1-(2-halophenyl)-1,3-diones has been developed. The procedure is based on a cascade copper-catalyzed intramolecular Ullmann-type C-arylation and rearrangement process. This methodology is tolerant of a wide range of substrates and applicable to library synthesis.