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Herein, we report a general strategy for the rational design of an efficient organic photocatalyst, and we describe a robust method for the direct C(sp3)–H carbamoylation of saturated aza-heterocyc...

A metal-free C(sp3)-H phosphorylation of saturated aza-heterocycles via the merger of organic photoredox and Bronsted acid catalyses was established under mild conditions. This protocol provided straightforward and economic access to a variety of valuable α-phosphoryl cyclic amines by using commercially available diarylphosphine oxide reagents. In addition, the D-A fluorescent molecule DCQ was used for the first time as a photocatalyst and exhibited an excellent photoredox catalytic efficiency in this transformation. A series of mechanistic experiments and DFT calculations demonstrated that this transformation underwent a sequential visible light photoredox catalytic oxidation/nucleophilic addition process.

A metal-free C(sp

Experiments were carried out with different apparatus to compact electrolytic copper powders at distinct loading speeds. It appears that green densities of compacts prepared by HVC out-number that by conventional compaction by one percent. Compacts by quasi-static compaction are almost as dense as those by HVC under comparable peak pressure. The relationship between green compact density and peak pressure accords with Hang Pei-yun formula well. Spring-backs of HVC compacts are far smaller than those of conventional compaction and quasi-static compaction. HVC compacts are harder than compacts by conventional compaction and quasi-static compaction when they have the same density.

Water atomized pure iron powder was pressed by high velocity compaction technology. The influences of impact velocity on green density, shock wave, compacting and ejection forces, radial springback and strength of compacts were studied. Cross-section images of green compacts were observed by scanning electron microscopy (SEM). A computer controlled universal testing machine was used to measure the green strength of compacts. The results show that impact velocity intensively affects the green density of specimen. As impact velocity increases, the green density and the strength of compacts increase gradually, especially the green strength. In addition, the compacting force and the actuation duration of shock wave increase obviously with the augment of impact velocity, which leads to densification of powder body. No specific relation was found between the ejection force, the radial springback and the impact velocity.

Iron powders with two different particle size distributions were compacted by high velocity compaction. The influences of particle size distribution and impact velocity on green properties, including green density, springback, tensile strength and bending strength etc., were studied with scanning electron microscopy (SEM) and a computer controlled universal testing machine. The results show that the particle size distribution and the impact velocity strongly affect its properties. Wider size distribution results in green compact with higher density and better strength. Furthermore, springback of compacts is lower produced by the powder with wider size distribution, especially for radial springback. As impact velocity increases, its green density and green strength gradually increases, but the increasing rate of density decreases gradually. No special relation is found between springback and impact velocity. In addition, the axial springback and the bending strength are higher than the radial springback and the tensile strength, respectively.