Basic Science

Actinide Polyrotaxane Successfully Prepared

Recently, Chemical Communications, an international journal published by the Royal Society of Chemistry, reported the successful preparation of the first case of actinide polyrotaxane, an important breakthrough in the construction of actinide supramolecules, from the Laboratory of Nuclear Energy Chemistry , Institute of High Energy Physics, CAS (Lei Mei, Zhi-fang Chai* and Wei-qun Shi*, et al. Chemical Communications. 2014, 50 (27), 3612-3615.). From 2011, the Laboratory of Nuclear Energy Chemistry of Division of Multidisciplinary Research Center, Institute of High Energy Physics, has endeavored to develop novel actinide functional hybrid materials and study their related features. Herein, a uranyl-based polyrotaxane has been obtained for the first time through a smart choice of ligand. In this compound, a typical pentagonal bipyramidal geometry of seven-coordinated uranyl species was found. Unlike common uranyl complexes, however, carbonate groups coordinated to central uranyl ion by alternating mono (η1) and bidentate (η2) -coordinated modes, leading to a distortion of the pentagonal bipyramid and subsequently forming a novel ‘dragon-like’ twist topology.

Solution to Local Void Problem

The Local Void problem is solved by a research group leaded by PhD. Student Xie Lizhi from the Computational Cosmology Group at National Astronomical Observatories of China. They used a high resolution cosmological N-body simulation (the Millennium-II Simulation) combined with a sophisticated semi-analytic galaxy formation model to statistically explore whether the Local Void is allowed within current knowledge of galaxy formation in standard cosmology model. The result is published on MNRAS (Xie, L., Gao, L., & Guo, Q., 2014, MNRAS 441, 933). They revised size and 'emptiness' of the Local Void using the most updated nearby galaxy catalog. Then they are looking for similar structure in simulation. Among 77 simulated Local Groups, 11 of them are associated with empty regions which have similar size, 'emptiness' and appearance (in projection image) as the observed Local Void. The paucity of faint galaxies in such voids results from a combination of two factors: a lower amplitude of the halo mass function in the voids than in the field, and a lower efficiency of galaxy formation in the void halos due to bias effects in halo assembly. This work suggested that, rather than a crisis, the Local Void is a success of standard cosmology model.

Big Step in Quantum Networks

The entangling of two independent photons of different colors has been realized for the first time by Prof. Pan Jianwei and his colleagues BaoXiaohui, Jiang Xiao, et al, and therefore finally solved the problem concerned with the interconnection between frequency-dissimilar terminals in quantum networks. The research result was recently published on the journal of Physical Review Letters as an Editors’Suggestion, while the Physics：Viewpoint of the American Physical Society also specifically reported the case. In their research, Prof. Pan Jianwei’s group proposed for the first time to apply time-resolved measurement and active feed-forward to realize the interconnection between frequency-dissimilar terminals in quantum networks, and conducted a demonstration of the proposal with the experimental platform of narrow-band entangled photons. The researchers found that the frequency separation between two input single photons will lead to different random phase-shift for the photons detected in different time, which will thus make two single photons no longer entangle each other. Thus, they developed a high-accurate time-resolved detection and fast active phase feed-forward system in this regard. Prof. Pan Jianwei’s group successfully realized the entangling of two independent photons with a frequency separation of 80 MHz, and the frequency difference is more than 16 times of the respective frequency width of each incident photon.

Advancement in Highly Efficient and Rapid Reprogramming System for iPSC

Somatic cell reprogramming towards induced pluripotent stem cells (iPSCs) holds great promise in future regenerative medicine, however, the reprogramming process mediated by the traditional defined factors (OSNK) is slow and extremely inefficient. Researchers from the Chen Dahua / Sun Qinmiao groups at Institute of Zoology, the CAS and the Jin Peng group at Emory University recently established a highly efficient and rapid reprogramming system for iPSC generation by using a combination of modified reprogramming factors (OySyNyK), in which the transactivation domain of the Yes-associated protein is fused to OCT4, SOX2 and NANOG respectively. They showed that the efficiency of OySyNyK-induced iPSCs was up to 100-fold higher than that of induction by traditional OSNK. Moreover they observed that the reprogramming by OySyNyK was very rapid (initiated at around 24 h versus 5 d by OSNK). Compared with OSNK, they found that OySyNyK factors significantly increased the expression of TET1 at the early stage, which interact with SOX2 and NANOG factors, and co-occupy pluripotency loci in the genome for somatic cell reprogramming. These studies not only establish a rapid and highly efficient iPSC reprogramming system, but also uncover a novel mechanism by which OSNK factors coordinate with TET proteins to regulate 5hmC-mediated epigenetic control, thereby promoting somatic cell reprogramming.