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[Display omitted] • Determine weights between subjective and objective weights based on game theory. • A new evaluation model of groundwater quality based on Game theory-HDT is proposed. • Propose a new dimensionless method to reduce computation and upgrade Game theory-HDT. To upgrade the groundwater quality evaluation model based on the Hasse diagram technique (HDT), this paper established a new evaluation model based on game theory and HDT. This new model, Upgraded-HDT, has been upgraded in three aspects: selection of the weighting method, combination of weights and simplification of the model calculation steps. The groundwater quality data of nine sample sites in Ganjingzi district of Dalian city in 2013 were used as a case to validate the model. The evaluation results of Upgraded-HDT showed that the groundwater quality of all sites was class III or better, apart from site 5, which was deeply affected by seawater intrusion and pollutant seepage. In addition, the evaluation results of the nemerow pollution index (NPI), fuzzy comprehensive evaluation (FCE), AHP-HDT, Entropy-HDT, Game theory-HDT and Upgraded-HDT were compared and analyzed. The results of AHP-HDT, although verifying the importance of expert experience in evaluating the model, were not sufficiently accurate at sites 4 and 6, while the results of Entropy-HDT at sites 7, 8 and 9 were overly optimistic and did not reflect the real situation of groundwater quality. Hence, the use of a single weighting method could not accurately evaluate water quality. The results of Game theory-HDT were the most accurate and the same as Entropy-HDT at site 4 and AHP-HDT at sites 6, 7 and 8. This showed that in game theory regarding the optimal combination of weights, the advantages of the two complement each other because both take into account the subjective initiative of people and avoid the one-sidedness of a single weighting method. Thus, the use of game theory was necessary. The results of Upgraded-HDT and Game theory-HDT agreed perfectly, which not only ensured the accuracy of the evaluation results but also reduced the computation of the HDT model. This proved that the dimensionless method proposed in this paper was feasible. The results of this study can provide a scientific basis for the protection and utilization of local groundwater resources and serve as a reference for water quality evaluation studies in other areas. [ABSTRACT FROM AUTHOR]

Interatomic potentials based on neural-network machine learning method have attracted considerable attention in recent years owing to their outstanding ability to balance the accuracy and efficiency in atomistic simulations. In this work, a neural-network potential (NNP) for carbon is generated to simulate the structural properties of various carbon structures. The potential is trained using a database consisting of crystalline and liquid structures obtained by the first-principles density functional theory (DFT) calculations. The developed potential accurately predicts the energies and forces in crystalline and liquid carbon structures, the energetic stability of defected graphene, and the structures of amorphous carbon as the function of density. The excellent accuracy and transferability of the NNP provide a promising tool for accurate atomistic simulations of various carbon materials with faster speed and much lower cost. [Display omitted] [ABSTRACT FROM AUTHOR]

• Using machine learning and game theory to optimize the combined weights. • Propose new aggregation functions of LQM and SWM. • WQI model is improved using the combined weights and aggregation functions. • Establishing a new water quality assessment system. To optimize the water quality index (WQI) assessment model, this study upgraded the parameter weight values and aggregation functions. We determined the combined weights based on machine learning and game theory to improve the accuracy of the models, and proposed new aggregation functions to reduce the uncertainty of the model. A new water quality assessment system was established, and took the Chaobai River Basin as a case study. To optimize the weight, two combined weights were established based on game theory. The weight CW AE was combined by the Analytic Hierarchy Process (AHP) and Entropy Weight Method (EWM). The weight CW AL was combined by AHP and machine learning (LightGBM). CW AL was judged to be an optimal composite weight by comparing the coefficient of variation (CV) values and the Kaiser-Meyer-Olkin (KMO) extracted values. To reduce the uncertainty of the model, we proposed two aggregation functions, the Sinusoidal Weighted Mean (SWM) and the Log-weighted Quadratic Mean (LQM). The three water quality assessment models (WQI S , WQI L and WQI W) were established based on the optimal weights besides. All three models had good reliability. Both WQI S and WQI W models had low eclipsing problems (25.49% and 18.63%). The accuracy of the models was ranked as WQI S > WQI W > WQI L. The uncertainty of WQIs (0.000) in assessing poor water quality was low, and so was WQI W (0.259) in assessing good water quality. Overall, the WQI S model was recommended for assessing poor water quality and the WQI W model was recommended for assessing good water quality. The assessment results of WQI S showed that the Chaobai River Basin was "slightly polluted", and the water quality upstream was better than that downstream. TN was the main pollutant in the basin, and there was slight pollution with COD Mn , COD Cr , BOD 5 , etc. There was little metal contamination, only a few months exceeded Class I. The model established in this study can provide a reference for the same type work of water quality assessment. The assessment results can provide a scientific basis for the protection of the regional water environment. [Display omitted] [ABSTRACT FROM AUTHOR]

A method to heal defects in reduced graphene oxide (RGO) is reported, accomplished by using methane + hydrogen plasma. The addition of hydrogen notably shifts the equilibrium between etching and growth of graphene, and suppresses the nucleation of carbon nanoparticles. The best recovery of RGO is observed at 800 °C, resulting in largest integrated Raman 2D/G peak area ratio (0.56) and highest Hall mobility (52 cm 2 V −1 s −1 ). A density functional theory calculation reveals that the repair process is dominated by reaction between the dangling bonds and CH 2 and CH radicals. [ABSTRACT FROM AUTHOR]

Abstract: The dependence of the absorbance of few-layer graphene oxide on reduction level is shown to originate from different inter- and intra-band transitions using infrared–visible spectroscopy. In addition, the band-gap of reduced graphene oxide is tunable from 2 to 0.02eV depending on its reduction level. These results indicate that reduced graphene oxide possesses great potential as a candidate for photodetection in the mid-infrared range by controlling its band-gap. This study not only gives further insight into the absorption mechanism of graphene oxide reduced to different levels, but also reveals a way to tune and measure the band-gap of graphene-based materials using a simple, economical, and nondestructive approach. This approach should be readily adapted for use in photodetection applications. [Copyright &y& Elsevier]

Abstract: Ultrafast third-order nonlinear optical responses of the as-deposited and annealed Cu:Bi2O3 nanocomposite films were investigated by using femtosecond Z-scan and time-resolved optical Kerr effect (OKE) techniques at the wavelength of 800nm. The Z-scan measurement showed that both the real and imaginary parts of the third-order nonlinear optical susceptibility were enhanced after thermal annealing treatment. The OKE response of the as-deposited film was instantaneous, and the enhanced OKE signal of the annealed film presented additional slow decay processes which imply the important contribution from photoinduced hot electrons in Cu nanoparticles. [Copyright &y& Elsevier]

Nanocrystalline CoFe2−xScxO4 (x=0–0.4) thin films were prepared on silicon substrates at reduced temperature by a sol–gel process, and the doping effects of scandium on the microstructure, magnetism and polar magneto-optical Kerr effects of the as-deposited films were examined. It was shown that the intensities of both of the Kerr rotation peaks increase with the doping content x of Sc3+. The increase for the peak at 540 nm is due to the decrease of the electrostatic polarization of O2− resulting from the relatively large radius of Sc3+, and that for the peak at 620 nm was a result of the migration of Co2+ from octahedral to tetrahedral sites in the presence of the dopant of Sc3+. [Copyright &y& Elsevier]