Complex Organic Molecules Formation in Cold Cores on Stochastically Heated Grains

We investigate the roles of stochastic grain heating in the formation of complex organic molecules (COMs) in cold cores, where COMs have been detected. Two different types of grain-size distributions are used in the chemical models. The first one is the MRN distribution, and the second one considers grain coagulation to study its effects on the chemical evolution in these environments. The macroscopic Monte Carlo method is used to perform the two-phase chemical model simulations. We find that (1) grain coagulation can affect certain gas-phase species, such as CO$_2$ and N$_2$H$^+$, in the cold core environments, which can be attributed to the volatile precursors originating from the small grains with temperature fluctuations; (2) grains with radii around 4.6 $\times$ 10$^{-3}$ $\mu$m contribute most to the production of COMs on dust grains under cold core conditions, while few species can be formed on even smaller grains with radii less than 2 $\times$ 10$^{-3}$ $\mu$m; (3) COMs formed on stochastically heated grains could help explain the observed abundances of gas-phase COMs in cold cores.Comment: 15 pages, 10 figures, 3 tables. Accepted by MNRA

Experimental of pumping gangue into the mined-out area

AbstractIn order to find solutions to the ground emission of gangue and realize the gangue pumping into the mined-out area, the underground experimental research is conducted in Shandong Huafeng Coalmine. Through the orthogonal experiment, the research deals with the effect of crushed particle size, mass concentration, and the amount of cement added on the pumping, filling, and the cost. As suggested by the experiment, the particle size of gangue has a significant effect on the pumpability of gangue-paste, and the amount of cement added obviously affects the compressive strength of the gangue-paste and the filling cost. According to the best experimented combination of particle size, the amount of cement added and mass concentration, this experimental system brings about an effective filling of the conventional mining-out area, and furthermore, provides a new approach for the disposal of gangue