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Six low-lying states ( X 2 Σ g + , A 2 Π u , B 2 Σ u + , 4 Σ g + , 4 Π u and 4 Σ u + ) of C 2 − anion are studied by highly correlated ab initio calculations. The potential energy curves (PECs) are computed in the internuclear separation from 0.8 to 5.0 Å using the complete active space self-consistent field method, and then performing the internally contracted multireference configuration interaction with Davidson correction. Core–valence correlation and scalar relativistic effect are considered through employing the aug-cc-pcV5Z-dk basis set. The spin–orbit coupling of the A 2 Π u state is also calculated using Breit–Pauli Hamiltonian. Based on the PECs derived from the high-level ab initio calculations, the spectroscopic parameters are obtained by fitting the ro-vibrational levels that are acquired by solving the ro-vibrational Schrödinger equation. These spectroscopic parameters, especially for low-lying doublet states, are in good agreement with the previously calculated and experimental results. Finally, the electronic transition dipole moment matrix elements, Franck–Condon factors, radiative lifetimes and oscillator strengths of A 2 Π u – X 2 Σ g + and B 2 Σ u + - X 2 Σ g + are calculated and discussed as well. [ABSTRACT FROM AUTHOR]

• It is the first review to compile FT-ICR-MS results for DOM in water treatments. • EEM-PARAFAC and FT-ICR-MS are two powerful tools for characterizing DOM. • The high diversity of DOM composition is a major challenge for water treatments. • Effects of water treatments on DOM are largely dependent on the DOM composition. • The DOM composition and its removal is key to optimize the treatment processes. Dissolved organic matter (DOM) plays a critical role in determining the quality of wastewater and the safety of drinking water. This is the first review to compare two types of popular DOM monitoring techniques, including absorption spectroscopy and fluorescence excitation-emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC) vs. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), for the applications in wastewater and drinking water treatments. The optical techniques provide a series of indices for tracking the quantity and quality of chromophoric and fluorescent DOM, while FT-ICR-MS is capable of identifying thousands of DOM compounds in wastewater and drinking water at the molecule level. Both types of monitoring techniques are increasingly used in studying DOM in wastewater and drinking water treatments. They provide valuable insights into the variability of DOM composition in wastewater and drinking water. The complexity and diversity of DOM highlight the challenges for effective water treatments. Different effects of various treatment processes on DOM are also assessed, which indicates that the information on DOM composition and its removal is key to optimize the treatment processes. Considering notable progress in advanced treatment processes and novel materials for removing DOM, it is important to continuously utilize these powerful monitoring tools for assessing the responses of different DOM constituents to a series of treatment processes, which can achieve an effective removal of DOM and the quality of treated water. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Previous researches focused on dry sample thermal treatment to enhance rock permeability indicate that thermal treatment can be a novel stimulation technique for geothermal and hydrocarbon reservoirs development. The mechanicm of thermal permeability enhancement depends on the generation of microcracks by thermal cracking. In this study, chemical solutions were introduced on sandstone rock samples and observed that they can be used to control thermal permeability enhancement. Sandstone specimens with the same order of permeability were saturated with different salt solutions and heated to different temperatures. The results quantify permeabilities and porosities of specimens saturated with electrolyts over them without chemical treatment but heated to the same temperature. The KCl solution had the largest effect on permeability enhancement for the tested rock and showed a tenfold increase in permeability, and followed by NaCl and K 2 CO 3 solutions. However, CaCl 2 solution and distilled water had negative effects. Laboratory results also revealed a positive correlation between some chemical concentration with the permeability increment of rock. The effects of electrolyte type and concentration on thermally permeability enhancement of the tested rocks were determined and a statistical model was fitted. The results show that the permeability increment follows an exponential growth with temperature when the rock was heated over the threshold temperature of thermal cracking. Introducing specific chemical species into a low-permeability formation and heating the formation beyond the threshold temperature of rock thermal cracking will be a promising way to further enhance formation permeability. • Reservoir rocks saturated different chemical agents were heated at high temperature. • Saturated rock has larger potential in permeability enhancement than dried one. • Types and concentrations of chemical agents largely affect the degree of rock thermal cracking. • Thermal stimulation with chemical agent is a promising way to enhance reservoir permeability. • An exponential growth model for permeability increment is proposed. [ABSTRACT FROM AUTHOR]