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Air pollution has become a critical issue in human’s life. Predicting the changing trends of air pollutants would be of great help for public health and natural environments. Current methods focus on the prediction accuracy and retain the forecasting time span within 12 hours. Shorter time span decreases the practicability of these perditions, even with higher accuracy. This study proposes an attention and autoencoder (A&A) hybrid learning approach to obtain a longer period of air pollution changing trends while holding the same high accuracy. Since pollutant concentration forecast highly relates to time changing, quite different from normal prediction problems like autotranslation, we integrate “time decay factor” into the traditional attention mechanism. The time decay factor can alleviate the impact of the value observed from a longer time before while increasing the impact of the value from a closer time point. We also utilize the hidden states in the decoder to build connection between history values and current ones. Thus, the proposed model can extract the changing trend of a longer history time span while coping with abrupt changes within a shorter time span. A set of experiments demonstrate that the A&A learning approach can obtain the changing trend of air pollutants, like PM2.5, during a longer time span of 12, 24, or even 48 hours. The approach is also tested under different pollutant concentrations and different periods and the results validate its robustness and generality.

catena-Poly[[[4-amino-N-(quinoxalin-2-yl)benzenesulfonamidato]aquacadmium(II)]-μ-4-amino-N-(quinoxalin-2-yl)benzenesulfonamidato], [Cd(C14H11N4O2S)2(H2O)], has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction, elemental analysis, fluorescence, IR and thermal analysis. Single-crystal X-ray analysis reveals that the complex is a one-dimensional zigzag chain structure, and the CdIIcation has a distorted octahedral coordination geometry formed by five N atoms from three different sulfaquinoxaline ligands and one O atom from a water molecule. The fluorescence spectrum reveals that the complex emits strong blue fluorescence and thermal analysis shows that the complex has high thermal stability.

Reaction of 5-aminosalicylic acid with 2-pyridinecarboxaldehyde or sodium chloroacetate gave two new ligands 5-((pyridin-2-yl)methyleneamino)-2-hydroxybenzoic acid (HL1) and 5-(bis(carboxymethyl)amino)-2-hydroxybenzoic acid (H2L2), respectively. Two compounds [Co(L1)2(H2O)2]·2H2O (1) and [Cu2(L2)2(phen)2] (2) (phen = 1,10-phenanthroline) were synthesized and characterized by IR, PXRD, TGA and cyclic voltammetry. Single crystal X-ray diffraction analysis reveals that complex 1 is a mononuclear structure and the metal center is coordinated in an octahedral geometry. Complex 2 is a dinuclear structure, in which the Cu atom is in a square pyramidal geometry. The cobalt ion is chelated by two 5-((pyridine-2-yl)methyleneamino)-2-hydroxybenzoinates to form a mononuclear structure. The compound an electrocatalytic activity of the reduction reaction from H2O2 to H2O.

catena-Poly[[bis{4-[(pyrimidin-2-ylazanidyl)sulfonyl]aniline}cobalt(II)]-bis[μ-1,3-bis(pyridin-4-yl)propane]], [Co(C10H8N4O4S2)2(C13H14N2)]nor [Co(L)2(bpp)]n, crystallizes as a one-dimensional polymeric structure which is further stabilized by intermolecular hydrogen bonding. The refined Flack parameter, −0.001 (10), indicates that the model represents the correct absolute structure. Investigation of the thermal stability shows that the complex is stable up to 543 K. The structure is of interest with respect to its electrochemical properties in the reduction reaction of H2O2to H2O.

Hydrothermal reaction of 4-sulfobenzoic acid monopotassium salt, H2C2O4 · 2H2O and Sm(NO3)3 · 6H2O, gave a new polymeric complex {[Sm2(sb)2(ox)(H2O)6] · 2H2O} n (1), (H2sb = 4-sulfobenzoic acid, ox = oxalate). X-ray diffraction analysis reveals that the complex, belonging to the triclinic system, space group , a = 5.9384(1), b = 7.9136(2), c = 14.7920(5) A, V = 646.92(3) A3, Z = 2, possesses a two-dimensional framework constructed by eight-coordinate Sm(III) centers. Magnetic susceptibility data of 1 are consistent with the existence of weak anti-ferromagnetic interactions. Thermogravimetric analysis shows that the structural framework of the compound is stable; the luminescence for 1 is also discussed.

To establish an HPLC method for determination of galangin in propolis.HPLC method was established. Diamonsil C18 column was used, CH3OH-4% H3PO4 solution (65:35) as mobile phase, at the flow rate of 1.0 ml/min and the UV detection wavelength at 256 nm.The linear of galangin was 0.00412 - 0.02472 mg/ml (r2 = 0. 9998). The content of galangin was the highest in the propolis from Shandong (11.7 mg/g). The content of galangin was higher in the propolis from Neimeng and Henan, respectively 10. 5 mg/g,10. 3 mg/g, the content of galangin was the lowest in the propolis from Gansu (9.8 mg/g).HPLC method is simple and reliable for determination of galangin in propolis.

The 2,7-bis(4-pyridyl)fluorene (BPF) was synthesized via a Suzuki coupling reaction. The optical spectra properties of BPF and BPF-deoxyribonucleic acid (DNA)-cetyltrimethyl ammonium (CTMA) thin films composed of BPF, DNA, and CTMA were characterized by the measurements of UV/Vis absorption spectra and fluorescence spectra. The amplified spontaneous emission (ASE) of the BPF-DNA-CTMA films was researched experimentally by pumping of a pulse laser with a wavelength of 355 nm. The results show that the absorption peak and the fluorescence peak of BPF are located at 327 and 380 nm, respectively. The emission peak of BPF corresponds to the vibronic transitions from an excited state of S 1 level to the ground state of S 0 level. The ASE peak of the BPF-DNA-CTMA film is located at 384 nm, and the threshold of ASE excited energy density is 3.12 mJ⋅cm −2 .

Two new 2D metal–organic frameworks were assembled in different conditions. Single X-ray diffraction analyses reveal that complex 1 possesses packing of large helical channels filled by guest water molecules; and 2 has a 2-fold interpenetration layer-like structure with relatively petite helical channels, with guest water molecules residing in the void spaces between neighboring helical layers. The diverse structures may result from dissimilar crystal growth mechanisms with distinct thermal stable energies confirmed by theoretical calculation. Photoluminescent spectra, thermogravimetric analyses and power X-ray diffraction analyses were performed.