The substructure and halo population of the Double Cluster hh and χ\chi Persei

In order to study the stellar population and possible substructures in the outskirts of Double Cluster $h$ and $\chi$ Persei, we investigate using the GAIA DR2 data a sky area of about 7.5 degrees in radius around the Double Cluster cores. We identify member stars using various criteria, including their kinematics (viz, proper motion), individual parallaxes, as well as photometric properties. A total of 2186 member stars in the parameter space were identified as members. Based on the spatial distribution of the member stars, we find an extended halo structure of $h$ and $\chi$ Persei, about 6 - 8 times larger than their core radii. We report the discovery of filamentary substructures extending to about 200 pc away from the Double Cluster. The tangential velocities of these distant substructures suggest that they are more likely to be the remnants of primordial structures, instead of a tidally disrupted stream from the cluster cores. Moreover, the internal kinematic analysis indicates that halo stars seems to be experiencing a dynamic stretching in the RA direction, while the impact of the core components is relatively negligible. This work also suggests that the physical scale and internal motions of young massive star clusters may be more complex than previously thought.Comment: 9 pagges, 9 figures, Accecpted to A&

The Ability of a Tetrel Bond to Transition a Neutral Amino Acid into a Zwitterion

The interaction between glycine and F2CO/F2SiO occurs through the formation of a π-tetrel bond between the C/Si atom and a carboxyl O atom. The interaction energy is some 20 kJ/mol for the C···O tetrel bond, but exceeds 300 kJ/mol for Si···O. As part of the latter complexation process, the proton engaged in the intramolecular OH··N H-bond is transferred across to the N, forming a zwitterion. This Si···O tetrel bond is more effective at inducing this proton transfer than is placement of the glycine in an aqueous medium, complexation with an anionic BH4-, or adding an electron to the glycine

Stability Analysis of Fractional Order Systems with Time Delay

In this paper, we mainly study the stability of linear and interval linear fractional systems with time delay. By applying the characteristic equations, a necessary and sufficient stability condition is obtained firstly, and then some sufficient conditions are deserved. In addition, according to the equivalent relationship of fractional order systems with order $0<\alpha\leq 1$ and with order $1\leq\beta<2$, one may get more relevant theorems. Finally, two examples are provided to demonstrate the effectiveness of our results

Stability Analysis of Fractional Order Systems with Time Delay

In this paper, we mainly study the stability of linear and interval linear fractional systems with time delay. By applying the characteristic equations, a necessary and sufficient stability condition is obtained firstly, and then some sufficient conditions are deserved. In addition, according to the equivalent relationship of fractional order systems with order $0<\alpha\leq 1$ and with order $1\leq\beta<2$, one may get more relevant theorems. Finally, two examples are provided to demonstrate the effectiveness of our results

(1R,3S)-Methyl 3-[(S)-2-(hydroxy­diphenyl­meth­yl)pyrrolidin-1-ylmeth­yl]-2,2-dimethyl­cyclo­propane­carboxyl­ate

The asymmetric unit of the title compound, C25H31NO3, prepared from (−)-1R-cis-caronaldehyde, contains three independent mol­ecules with similar conformations. The hydr­oxy groups are involved in intra­molecular O—H⋯N hydrogen bonds. The crystal packing exhibits weak inter­molecular O—H⋯O and C—H⋯O hydrogen bonds