A hybrid deep learning model for regional O3 and NO2 concentrations prediction based on spatiotemporal dependencies in air quality monitoring network.

Short-term prediction of urban air quality is critical to pollution management and public health. However, existing studies have failed to make full use of the spatiotemporal correlations or topological relationships among air quality monitoring networks (AQMN), and hence exhibit low precision in regional prediction tasks. With this consideration, we proposed a novel deep learning-based hybrid model of Res-GCN-BiLSTM combining the residual neural network (ResNet), graph convolutional network (GCN), and bidirectional long short-term memory (BiLSTM), for predicting short-term regional NO2 and O3 concentrations. Auto-correlation analysis and cluster analysis were first utilized to reveal the inherent temporal and spatial properties respectively. They demonstrated that there existed temporal daily periodicity and spatial similarity in AQMN. Then the identified spatiotemporal properties were sufficiently leveraged, and monitoring network topological information, as well as auxiliary pollutants and meteorology were also adaptively integrated into the model. The hourly observed data from 51 air quality monitoring stations and meteorological data in Shanghai were employed to evaluate it. Results show that the Res-GCN-BiLSTM model was better adapted to the pollutant characteristics and improved the prediction accuracy, with nearly 11% and 17% improvements in mean absolute error for NO2 and O3, respectively compared to the best performing baseline model. Among the three types of monitoring stations, traffic monitoring stations performed the best for O3, but the worst for NO2, mainly due to the impacts of intensive traffic emissions and the titration reaction. These findings illustrate that the hybrid architecture is more suitable for regional pollutant concentration.

A three-dimensional Cu-Na heteronuclear coordination polymer based on iminodiacetic acid.

A novel Cu-Na heteronuclear three-dimensional coordination polymer, poly[diaquadi-µ5-iminodiacetato-di-µ4-iminodiacetato-tricopper(II)disodium(I)], [Cu3Na2(C4H5NO4)4(H2O)2]n, has been prepared by hydrothermal synthesis. The asymmetric unit contains one and a half copper(II) cations, a sodium cation, two iminodiacetate (ida) ligands and a coordinated water ligand. One of the two independent Cu(II) centres is in a general position and is five-coordinated in a distorted square-pyramidal geometry. A [Cu(ida)] unit is formed via a bis-chelating ida ligand and the coordination sphere of the Cu(II) atom is completed by two O atoms of two different neighbouring [Cu(ida)2] units. These [Cu(ida)2] units are associated with the second Cu(II) cation, which is located on a crystallographic inversion centre and is coordinated in a distorted square-planar geometry by two chelating ida ligands. The carboxylate groups of the ida ligands act as bridges and connect the [Cu(ida)] and [Cu(ida)2] building blocks in a 2:1 ratio, forming two-dimensional arrays. These layers are interconnected into a three-dimensional structure by the sodium ions. Each Na(I) cation is coordinated by six O atoms from five ida ligands and a water molecule. When [Cu(ida)], the Na(I) cations and [Cu(ida)2] are viewed as 5-, 5- and 8-connected nodes, respectively, the three-dimensional network exhibits a (3(2).4(3).5(2).6(3))2(3(2).4(3).5(2).6(3))2(3(4).6(16).7(8)) topology.

Diiodido[methyl 2-(quinolin-8-yl-oxy)-acetate-κN]mercury(II).

In the title mononuclear complex, [HgI(2)(C(12)H(11)NO(3))], the Hg(II) ion has a distorted trigonal-planar coordination sphere defined by two I(-) anions and the N atom of a methyl 2-(quinolin-8-yl-oxy)acetate ligand. In the crystal, face-to-face π-π stacking inter-actions, with a centroid-centroid distance of 3.563 (9) Å, are observed.

Dichlorido[methyl 2-(quinolin-8-yl-oxy-κ(2)N,O)acetate-κO]mercury(II).

In the neutral title complex, [HgCl(2)(C(12)H(11)NO(3))], the Hg(II) ion is penta-coordinated by two Cl atoms, one N atom and two weakly coordinating O atoms from the methyl 2-(quinolin-8-yl-oxy)acetate ligand. The coordination around the Hg(II) ion may be described as highly distorted trigonal-bipyramidal. Centrosymmetric dimers are formed by an additional weak Hg⋯Cl inter-action, leading to a distorted octa-hedral coordination geometry around the Hg(II) ion.

Dibromido[methyl 2-(quinolin-8-yl-oxy-κ(2)N,O)acetic acid-κO]mercury(II).

In the title complex, [HgBr(2)(C(12)H(11)NO(3))], the Hg(II) ion has a distorted core trigonal-planar geometry comprising two Br atoms and one quinoline N atom of the methyl 2-(quinolin-8-yl-oxy)acetic acid ligand. The angles around the Hg atom vary from 100.31 (15) to 152.65 (4)°. Two additional Hg⋯O inter-actions [2.739 (1) and 2.905 (1) Å] complete the coordination sphere about the Hg(II) atom.

[Prevention and control of invaded plant Phytolacca americana in sandy coastal shelter forests].

The invasion of Phytolacca americana has produced serious damage to the coastal shelter forests in China. In order to search for the effective measures for controlling the growth of P. americana, several plots in the Robinia pseudoacacia forest invaded by P. Americana to the relatively same extent were installed, and the measures of physical control (mowing and root cutting) and chemical control (spraying herbicides) were adopted to control the invasion of P. Americana, taking the site with good growth of Amorpha fruticosa in the forest and without any control measures as the comparison. The results showed that mowing could rapidly decrease the growth of P. americana in the same year, but the growth recovered in the next year. 1/3 root cutting only reduced the aboveground growth of P. americana in the same year, and the growth was recovered in the third year; while 2/3 root cutting and whole cutting could effectively cleanup the P. americana plants all the time. Spraying quizalofop-p-ethyl and paraquat only killed the aboveground part of P. americana in the same year, but this part of P. americana recovered to the normal level in the next year; while spraying 45 g x L(-1) of glyphosate could completely kill the whole P. americana plants till the third year. The growth of P. americana at the site with good growth of A. fruticosa and without any control measures maintained at a low level all the time, suggesting that planting A. fruticosa in R. pseudoacacia forest would be an effective approach to prevent and control the P. americana invasion.

catena-Poly[[dibromidomercury(II)]-µ-3,6-bis-(2-pyridyl-sulfan-yl)pyridazine-κN:N].

In the title coordination polymer, [HgBr(2)(C(14)H(10)N(4)S(2))](n), the Hg(II) atom is four-coordinated in a distorted tetra-hedral geometry by the two N atoms of the pyridyl groups of different 3,6-bis-(2-pyridyl-sulfan-yl)pyridazine ligands and two Br atoms. The bridging function of the cis ligands leads to a helical chain structure along [100].

[N-(8-Quinolylmeth-yl)imino-diethanol-κN,N',O,O']bis-(thio-cyanato-κN)nickel(II) monohydrate.

In the neutral title complex, [Ni(NCS)(2)(C(14)H(18)N(2)O(2))]·H(2)O, the Ni(II) ion has a distorted octa-hedral geometry with cis-isothio-cyanate ligands.