Equilibrium bifurcation and extreme risk in the EU carbon futures market.

Considering the long-term memory and volatility clustering of the European Union (EU) Carbon Emission Allowances (EUA) futures returns, based on the economy-energy-environment system perspective and the assumption of investors' heterogeneity, this study proposes a joint modeling approach combining the fractionally integrated generalized autoregressive conditional heteroscedasticity model (FIGARCH) and the stochastic cusp catastrophe model (SCC) to examine the equilibrium bifurcations and extreme risks in the EU carbon futures market. The relevant results are threefold. (1) The SCC model has good fitting effect and interpretability, and is an effective method for investigating catastrophe reactions under time-varying volatility conditions.

Time point and scale measurement of carbon sink trading market risk based on catastrophe entropy and potential function.

According to the principle of total entropy change of dissipative structure, the carbon trading market is defined as a nonlinear complex system that follows the law of entropy increase in this paper. Based on the potential function of sudden change theory, this paper studies the risk point and scale of the carbon trading market. The results show that (1) the theory of dissipative structure and catastrophe theory can be used as the theoretical basis of carbon financial market risk research, and its core technology can be used to measure and predict risks.

Poly[tetra-aqua-(5-hy-droxy-pyridin-1-ium-3-carboxyl-ato-κO (3))tris-(μ-oxalato-κ(4) O (1),O (2):O (1'),O (2'))dieuropium(III)].

In the title compound, [Eu2(C6H5NO3)2(C2O4)3(H2O)4] n , the Eu(III) atom is bonded to one O atom from a monodentate 5-hy-droxy-pyridin-1-ium-3-carboxyl-ate ligand, six O atoms from three oxalate ligands and two water mol-ecules, exhibiting a highly distorted tricapped trigonal geometry. Three independent oxalate ligands, each lying on an inversion center, bridge the Eu(III) atoms, forming a brickwall-like layer parallel to (001), which is stabilized by intra-layer O-H⋯O hydrogen bonds. The layers are further linked through inter-layer O-H⋯O and N-H⋯O hydrogen bonds and π-π inter-actions between the pyridine rings [centroid-centroid distance = 3.

Poly[[diaqua-bis-(μ-oxalato-κ(4)O(1),O(2):O(1'),O(2'))bis-(μ(3)-5-oxidopyridin-1-ium-3-carboxyl-ato-κ(3)O(3):O(3'):O(5))diholmium(III)] dihydrate].

In the title compound, {[Ho(2)(C(6)H(4)NO(3))(2)(C(2)O(4))(2)(H(2)O)(2)]·2H(2)O}(n), the Ho(III) atom is coordinated by three O atoms from three 5-hy-droxy-nicotinate ligands, four O atoms from two oxalate ligands, each lying on an inversion center, and one water mol-ecule in a distorted square-anti-prismatic geometry. The 5-hy-droxy-nicotinate ligand is protonated at the N atom and deprotonated at the hy-droxy group. The Ho(III) atoms are bridged by the carboxyl-ate and phenolate O atoms, forming a three-dimensional framework.