Aims. We seek to understand how the 4.8 GHz formaldehyde absorption line is distributed in the MON R2, S156, DR17/L906, and M17/M18 regions. More specifically, we look for the relationship among the H 2 CO, 12 CO, and 13 CO spectral lines. Methods. The four regions of MON R2 (60 × 90 ), S156 (50 × 70 ), DR17/L906 (40 × 60 ), and M17/M18 (70 × 80 ) were observed for H 2 CO (beam 10 ), H110α recombination (beam 10 ), 6 cm continuum (beam 10 ), 12 CO (beam 1 ), and 13 CO (beam 1 ). We compared the H 2 CO, 12 CO, 13 CO, and continuum distributions, and also the spectra line parameters of H 2 CO, 12 CO, and 13 CO. Column densities of H 2 CO, 13 CO, and H 2 were also estimated. Results. We found out that the H 2 CO distribution is similar to the 12 CO and the 13 CO distributions on a large scale. The correlation between the 13 CO and the H 2 CO distributions is better than between the 12 CO and H 2 CO distributions. The H 2 CO and the 13 CO tracers systematically provide consistent views of the dense regions. Their maps have similar shapes, sizes, peak positions, and molecular spectra and present similar central velocities and line widths. Such good agreement indicates that the H 2 CO and the 13 CO arise from similar regions.

Easy-to-implement methods were realized with glucose-based gelators for the efficient removal of aniline/nitrobenzene, and toxic dyes from contaminated water.

In this work, we present the new catalog of carbon stars from the LAMOST DR2 catalog. In total, 894 carbon stars are identified from multiple line indices measured from the stellar spectra. Combining the CN bands in the red end with C 2 and other lines, we are able to identify the carbon stars. Moreover, we also classify the carbon stars into spectral sub-types of C-H, C-R, and C-N. These sub-types approximately show distinct features in the multi-dimensional line indices, implying that in the future we can use them to identify carbon stars from larger spectroscopic datasets. Meanwhile, from the line indices space, while the C-N stars are clearly separated from the others, we find no clear separation between C-R and C-H sub-types. The C-R and C-H stars seem to smoothly transition from one to another. This may hint that the C-R and C-H 2 Ji et al.stars may not be different in their origins but look different in their spectra because of different metallicity. Due to the relatively low spectral resolution and lower signalto-noise ratio, the ratio of 12 C/ 13 C is not measured and thus the C-J stars are not identified.