Direct Incorporation of Dinitrogen into an Aliphatic C-H Bond.

The activation of dinitrogen (N2) and direct incorporation of its N atom into C-H bonds to create aliphatic C-N compounds remains unresolved. Incompatible conditions between dinitrogen reduction and C-H functionalization make this process extremely challenging. Herein, we report the first example of dinitrogen insertion into an aliphatic Csp3-H bond on the ligand scaffold of a 1,3-propane-bridged [N2N]2--type dititanium complex. Mechanistic investigations on the behaviors of dinuclear and mononuclear Ti complexes indicated the intramolecular synergistic effect of two Ti centers at a C-N bond-forming step. Computational studies revealed the critical isomerization between the inactive side-on N2 complex and the active nitridyl complex, which is responsible for the Csp3-H amination. This strategy maps an efficient route toward the future synthesis of aliphatic amines directly from N2.

Generation of Leydig-like cells: approaches, characterization, and challenges.

Testosterone production by Leydig cells (LCs) plays a crucial role in male reproduction. The functional degeneration of LCs can cause testosterone deficiency, ultimately resulting in primary male hypogonadism. Transplantation of exogenous LCs with the ability to produce testosterone in response to the regulation of the hypothalamus-pituitary-gonad axis could be a promising alternative option to treat male primary hypogonadism. Recent studies have shown that it is possible to generate Leydig-like cells from stem cells by various approaches. In addition, somatic cells, such as embryonic or adult fibroblasts, have also been successfully reprogrammed into Leydig-like cells. In this review, we summarized the recent advances in the generation of Leydig-like cells, with an emphasis on comparing the effectiveness and safety of different protocols used and the cells generated. By further analyzing the characteristics of Leydig-like cells generated from fibroblasts based on small signaling molecules and regulatory factors, we found that although the cells may produce testosterone, they are significantly different from real LCs. For future in vivo applications, it is important that the steroidogenic cells generated be evaluated not only for their steroidogenic functions but also for their overall cell metabolic state by proteomics or transcriptomic tools.

Localization and oscillation of optical beams in Moiré lattices.

We study the propagation of optical beams in two-dimensional Moiré lattices, and demonstrate position-dependent beam dynamics when a quasi-Bragg condition is satisfied. We show that when the optical beam is incident to a peak of the lattice envelop, an optical Zitterbewegung is obtained. If the optical beam is incident to a node of the envelop, a field localization effect takes place. The localized beam oscillates with a much larger spatial period than that of the optical Zitterbewegung. Variation of the oscillation period versus the split in periods is discussed. The position-dependent beam dynamics are explained by the excitation of proper bandedge eigenmodes of the Moiré lattice, and can be engineered via tuning the periods of the two superimposed Bragg lattices.