Research on the Dynamic Evolution and Influencing Factors of Energy Resilience in China

Energy security is the guarantee for achieving the goal of carbon peaking and carbon neutrality, and exploring energy resilience is one of the important ways to promote energy security transition and adapt to changes in international and domestic energy markets. This paper applies the combined dynamic evaluation method to measure China's energy resilience level from 2004-2021, analyses the spatio-temporal dynamic evolution of China's energy resilience through the center of gravity-standard deviation ellipse and kernel density estimation, and employs geo-detectors to detect the main influencing factors and interactions of China's energy resilience. The study finds that:(1)China's energy resilience level generally shows a zigzagging forward development trend, and the spatial imbalance characteristic of China's energy resilience is more obvious.(2)The spatial dynamics of China's energy resilience level evolves in a northeast-southwest direction, and the whole moves towards the southwest, with an overall counterclockwise trend of constant offset.(3)When the energy resilience level of neighboring provinces is too low or too high, it has little effect on the improvement of the energy resilience level of the province; when the energy resilience level of neighboring provinces is 1-1.4, it has a positive spatial correlation with the energy resilience level of the province, and the synergistic development of the provinces can improve the energy resilience level together.(4)GDP, the number of employees, the number of employees enrolled in basic pension and medical insurance, and the number of patent applications in high-tech industries have a more significant impact on China's energy resilience, while China's energy resilience is affected by the interaction of multiple factors

Stacking tunable interlayer magnetism in bilayer CrI3

Diverse interlayer tunability of physical properties of two-dimensional layers mostly lies in the covalent-like quasi-bonding that is significant in electronic structures but rather weak for energetics. Such characteristics result in various stacking orders that are energetically comparable but may significantly differ in terms of electronic structures, e.g. magnetism. Inspired by several recent experiments showing interlayer anti-ferromagnetically coupled CrI3 bilayers, we carried out first-principles calculations for CrI3 bilayers. We found that the anti-ferromagnetic coupling results from a new stacking order with the C2/m space group symmetry, rather than the graphene-like one with R3 as previously believed. Moreover, we demonstrated that the intra- and inter-layer couplings in CrI3 bilayer are governed by two different mechanisms, namely ferromagnetic super-exchange and direct-exchange interactions, which are largely decoupled because of their significant difference in strength at the strong- and weak-interaction limits. This allows the much weaker interlayer magnetic coupling to be more feasibly tuned by stacking orders solely. Given the fact that interlayer magnetic properties can be altered by changing crystal structure with different stacking orders, our work opens a new paradigm for tuning interlayer magnetic properties with the freedom of stacking order in two dimensional layered materials

Structure and tanning properties of dialdehyde carboxymethyl cellulose: Effect of degree of substitution

Content: Developing novel tanning agents from renewable biomass is regarded as an effective strategy for sustainable leather industry. In this study, a series of dialdehyde carboxymethyl cellulose (DCMC) were prepared by periodate oxidation of carboxymethyl cellulose (CMC) with varying degrees of substitution (DS: 0.7, 0.9 and 1.2). The structural properties of DCMC were characterized. Size Exclusive Chromatography measurements showed that CMC underwent severe degradation during periodate oxidation, resulting in the decline of weight-average molecular weight from 250,000 g/mol to around 13,000 g/mol. FT-IR analysis illustrated that aldehyde group was successfully introduced into DCMC. The aldehyde group content of DCMC decreased from 8.38 mmol/g to 2.95 mmol/g as the DS rose from 0.7 to 1.2. Interestingly, formaldehyde was found to be produced in DCMC, and its content was 159.4, 151.7 and 38.4 mg/L, respectively when the DS of CMC was 0.7, 0.9 and 1.2, respectively. Further analysis by HPLC found that fructose was formed during oxidative degradation, and was subsequently oxidized to generate formaldehyde. This was in accordance with the fact that higher DS resulted in lower formaldehyde content in DCMC. The whole reaction mechanism is still under investigation at the moment. Tanning trials showed that the shrinkage temperature and thickening rate of DCMC tanned leather decreased as the DS increased. This should be due to the difference in aldehyde content of DCMC. Leather tanned by DCMC-0.7 (DS of CMC was 0.7) had the highest shrinkage temperature of 81°C and thickening rate of 76%. It was noteworthy that the formaldehyde content in DCMC tanned leather was only 0.11-0.40 mg/kg even though DCMC contained a small amount of formaldehyde. In general, we hope the work on dialdehyde tanning agent derived from CMC could provide some essential data for the development of sustainable tanning material and process. Take-Away: 1. Higher degree of substitution (DS) of CMC resulted in lower aldehyde group content of DCMC. 2. The formaldehyde content of DCMC was negatively correlated with DS. 3. The tanning performance of DCMC with lower DS was better