Exploring the role of potassium ferrate and straw fiber in enhancing the strength of cement-based solidified municipal sludge.

The effect of potassium ferrate (PF) and straw fiber (SF) on the strength of cement-based solidified municipal sludge, including the influence of reducing the organic matter in the sludge on the efficiency of the hydration of the cement, was studied. Single-factor tests, orthogonal tests, and linear weighted optimization methods were used to obtain suitable ratios to meet practical requirements, and then SEM and XRD analyses were used to explore the solidification mechanism. The results showed that PF and SF had significant influence on the strength, with SF having the greatest influence and the strength increasing with the amount of both admixtures, and cement had no significant influence on the strength. After linear weighting optimization, the ideal dosage was found to be 20% cement, 20% PF, and 5% SF, which produced a solidified sludge that had an strength of 126.87 kPa, far higher than the 50 kPa required to qualify for disposal in landfills. Analysis of the mineral content and microstructure showed that PF and SF could promote cement hydration and produce more hydration products, and the density of the optimized sample was much higher than that of the raw sludge and a sludge sample mixed with 20% cement alone.

A theoretical study of the electrochemical reduction of CO2 on cerium dioxide supported palladium single atoms and nanoparticles.

Pd/CeO2 catalysts show superior catalytic performance owing to their optimal cycling activity and stability. In this study, single-atom Pd and eight-atom Pd nanoparticle clusters were supported on the surface of CeO2(110) to investigate the effect of loaded-metal size on the catalytic performance of the Pd-CeO2 system for CO2 reduction. We investigated the CO2 reduction reaction (CRR) that produces C1 products (CO, HCOOH, CH3OH, and CH4) on Pd8/CeO2 and Pd/CeO2 by density functional theory. The structures, CO2 adsorption configurations, and CO2 reduction mechanisms of these two electrocatalysts were systematically studied. Subsequently, different reduction pathways on Pd8/CeO2 and Pd/CeO2 were investigated to identify the optimal reaction pathway for further assessment. The results showed that both of these catalysts are more selective towards the production of CH3OH than CH4. Moreover, compared to Pd/CeO2 and Pd4/CeO2 (from a previously reported study) the production of CH3OH via the CRR on Pd8/CeO2 exhibited the lowest limiting potential. These results demonstrate the superiority of Pd8/CeO2 as an electrocatalyst for the electrochemical reduction of CO2 to CH3OH.

Theoretical exploration of the nanoscale host-guest interactions between [n]cycloparaphenylenes (n = 10, 8 and 9) and fullerene C60: from single- to three-potential well.

The nanoscale host-guest interactions between [n]cycloparaphenylene ([n]CPP; n = 10, 8 and 9) nano-ring and fullerene C60 were explored theoretically. It is found that relatively small variations in the sizes of the [n]CPP host lead to very significant changes in encapsulation property toward the fullerene C60 guest. Expectedly, one stable inclusion-configuration of [10]CPP⊃C60 and one floating-configuration of [8]CPP⊃C60 are located on the potential surfaces of the two complexes, respectively. Unexpectedly, besides a floating-configuration (F-[9]CPP⊃C60), another stable inclusion-configuration (I-[9]CPP⊃C60) is also located on the potential surface of [9]CPP⊃C60 host-guest complex. Interaction energies and natural steric analysis show that these complexes are stabilized by balancing concave-convex π-π attractive and steric repulsive host-guest interactions. In contrast, the steric repulsive energy (Es) between host and guest of I-[9]CPP⊃C60 is as high as 233.12 kJ mol(-1), which is much larger than those in other complexes. The movements of C60 guest through the cavities of [n]CPP host (n = 10, 8 and 9) are simulated by calculating the energy profile, and the results interestingly reveal that the encapsulation of C60 by [10]CPP is in the manner of a single-potential well, by [8]CPP in the manner of a double-potential well, and by [9]CPP in the special manner of a three-potential well. We predict that the movement of C60 guest through the cavity of [9]CPP host should be experimentally observable owing to the relatively low energy barrier (<50 kJ mol(-1), M06-2X/6-31G(d)). Charge population analysis shows that an obvious charge transfer between host and guest takes place during the formation of I-[9]CPP⊃C60, which is different from those during the formation of [8]CPP⊃C60, [10]CPP⊃C60 and F-[9]CPP⊃C60. Additionally, the host-guest interaction regions were detected and visualized in real space based on the electron density and reduced density gradient.

Structure-property relationship of amplified spontaneous emission in organic semiconductor materials: TPD, DPABP, and NPB.

N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) was demonstrated to be suitable for stimulated emission in doping and nondoping planar waveguide structure, but the mechanism for its lasing is of ambiguity. With the aim of providing a microsscopic picture for its lasing, we performed a combined experimental and theortical investigation of the absorption, photoluminescence (PL), and stimulated emission of TPD and other two similar molecules: 1,4-bis (diphenylamino)biphenyl (DPABP) and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4″-diamine (NPB). It was found that DPABP shows the same amplified spontaneous emission (ASE) characteristics as TPD, but NPB did not. In theory, density functional theory (DFT) and Franck-Condon Principle were used to analyze the molecular geometry in the electronic ground state as well as the optically excited state and the vibrational levels in electronic ground state, respectively. The calculation results show that for TPD and DPABP, several strongly elongated high-frequency modes (1199-1664 cm(-1)) in the carbon rings contribute to the distinct first vibronic sideband in the PL spectra, which form an effective four-level system for lasing. For NPB, when the peripheral toluene or benzene is replaced with naphthyl, a number of strongly elongated low-frequency modes (11-689 cm(-1)) deriving from naphthyl leads to a series of energy sublevels, which destroys the four-level system. Our results provided a new insight and better understanding into the lasing of organic molecules.

Spatiotemporal change in ecological quality and its influencing factors in the Dongjiangyuan region, China.

It is of great significance for regional ecological protection and sustainable development to quickly and effectively assess and monitor regional ecological quality and identify the factors that affect ecological quality. This paper constructs the Remote Sensing Ecological Index (RSEI) based on the Google Earth Engine (GEE) platform to analyze the spatial and temporal evolution of ecological quality in the Dongjiangyuan region from 2000 to 2020. An ecological quality trend analysis was conducted through the Theil-Sen median and Mann-Kendall tests, and the influencing factors were analyzed by using a geographically weighted regression (GWR) model. The results show that (1) the RSEI distribution can be divided into the spatiotemporal characteristics of "three highs and two lows," and the proportion of good and excellent RSEIs reached 70.78% in 2020. (2) The area with improved ecological quality covered 17.26% of the study area, while the area of degradation spanned 6.81%. The area with improved ecological quality was larger than that with degraded ecological quality because of the implementation of ecological restoration measures. (3) The global Moran's I index gradually decreased from 0.638 in 2000 to 0.478 in 2020, showing that the spatial aggregation of the RSEI became fragmented in the central and northern regions. (4) Both slope and distance from roads had positive effects on the RSEI, while population density and night-time light had negative effects on the RSEI. Precipitation and temperature had negative effects in most areas, especially in the southeastern study area. The long-term spatiotemporal assessment of ecological quality can not only help the construction and sustainable development of the region but also have reference significance for regional ecological management in China.

Chemically modified fullerene derivatives as photosensitizers in photodynamic therapy: a first-principles study.

The first-principles density functional theory (DFT) and its time-dependent approach (TD-DFT) are used to characterize the electronic structures and optical spectra properties of five chemically modified fullerenes. It is revealed that the metal fullerene derivatives possess not only stronger absorption bands in visible light regions than organically modified fullerene but also the large energy gaps (ΔE(S-T) > 0.98 eV) between the singlet ground state and the triplet state, which imply their significant aspect of potential candidates as a photosensitizer. We have found that a new metal-containing bisfullerene complexes (Pt(C(60) )(2) ), with the extended conjugated π-electrons, much degenerate orbitals and a uniform electrostatic potential surface, behave more pre-eminent photosensitizing properties than other examined fullerene derivatives.

The impact of avoidant attachment on marital satisfaction of Chinese married people: Multiple mediating effect of spousal support and coping tendency.

In this study, the relationship between attachment avoidance and marital satisfaction of Chinese married people as well as the multiple mediating role of spousal support and coping tendency were explored. A model was developed using data of a sample of 510 Chinese married people. Four scales (the Experience of Close Relationships Scale, the Support Scale in Intimate Relationships, the Simple Coping Style Scale, and the Olson Marital Quality Questionnaire) were used to assess attachment avoidance, spousal support, coping tendency, and marital satisfaction, respectively. The results of correlation analysis showed that attachment avoidance was significantly negatively correlated with spousal support, coping tendency, and marital satisfaction. Spousal support was significantly positively correlated with both coping tendency and marital satisfaction. Coping tendency was significantly positively correlated with marital satisfaction. The mediation model indicated significant mediating effects of spousal support and coping tendency between attachment avoidance and marital satisfaction, respectively, where the mediating path of spousal support exerted the largest effect. The multiple mediating effect of attachment avoidance → spousal support → coping tendency → marital satisfaction was also significant. Chinese married people with high levels of attachment avoidance might perceive lower levels of spousal support and are therefore more inclined to employ negative coping when handling conflicts, which lowers marital satisfaction.

Measuring the Efficiency of Fiscal Policies for Environmental Pollution Control and the Spatial Effect of Fiscal Decentralization in China.

This paper uses both fiscal expenditure policy and fiscal revenue policy as input indicators and selects environmental pollution control results reflecting different forms and sources of pollution as output indicators. The efficiency of fiscal policies for environmental pollution control (EFPE) of 30 provincial-level administrative divisions in China from 2007 to 2017 is measured by adopting the data envelopment analysis (DEA) method. Then, the spatial effect of fiscal decentralization on EFPE is empirically analyzed by using the spatial lag model (SLM). The results show that EFPE values in China have been greatly improved overall since 2014. The change in technical efficiency (TE) is caused mainly by the change in pure technical efficiency (PTE). EFPE values have regional heterogeneity and convergence. The eastern region has clearly higher EFPE values than other regions. The growth rate of the low efficient region is greater than that of the high efficient region. Fiscal expenditure decentralization has a direct negative effect and spatial spillover effect on EFPE values, while fiscal revenue decentralization has a non-significant effect. Based on these results, this paper proposes the following policy implications: increasing the level of fiscal expenditure of environmental pollution control and improving the central transfer payment system for environmental protection; reforming the government performance assessment system and innovating the conditions of government expenditure on environmental pollution control; and promoting horizontal fiscal cooperation in cross-regional environmental governance.

Methylene blue functionalized graphene as binder-free electrode for high-performance solid state supercapacitors.

Electrochemical active small organic molecules are potential electrode materials for supercapacitors due to their sustainable and good redox reversibility. However, the poor electrical conductivity restricts their application in supercapacitors. Herein, a water soluble organic dye of methylene blue (MB) has been supported on graphene (GR) through a facile ultrasonic method to form a methylene blue/graphene (MB/GR) composite. A small amount of MB (13%) in MB/GR composite improves the wettability of GR and supplies pseudocapacitance. The MB/GR composite can be used as a binder-free electrode for supercapacitors, and gives a high specific capacitance of 517 F g-1 at 0.5 A g-1 in 0.5 mol L-1 H2SO4 aqueous electrolyte with a satisfactory capacitive retention of 91% after 2000 consecutive cyclic voltammetry tests at 10 mV s-1. Benefiting from the high specific capacitance of MB/GR composite, the as-assembled symmetrical solid-state supercapacitor (MB/GR//MB/GR) delivers a high energy density of 30.36 Wh kg-1 at 0.7 kW kg-1, and excellent cycle stability (nearly 27% drop after 10,000 consecutive constant current charge-discharge at 5 A g-1). This work offers some enlightenment to design and preparation of high-performance electrode materials for supercapacitors.

Assessing Changes in Ecosystem Service Values in Response to Land Cover Dynamics in Jiangxi Province, China.

This paper examines the ecosystem service values of Jiangxi province, China using the benefit transfer approach. The land cover dynamics results show that cropland and forest are the main land cover types in Jiangxi province. Urban land drastically increased after 2000, expanding from 846.54 km2 in 2000 to 2317.48 km2 in 2015. Forest and water obviously decreased across the study periods. Consequently, the total ecosystem service values decreased from 37.91 × 1010 Yuan in 1995 to 35.27 × 1010 Yuan in 2015. The values showed a declining trend, especially during the 1995-2000 period. The largest declines in ecosystem service values were caused by decreases in forest and water cover. Regulating services experienced the largest declines in ecosystem services value. Moreover, water supply showed the largest decline in ecosystem service value between 1995 and 2015. Not surprisingly, food production increased in the whole period, especially in the 1995-2000 period. Forest and cropland played the most important roles in the total ecosystem service values of Jiangxi province. We then discussed the relationship among ecosystem services based on the ecosystem service trade-off degree. The results show that the dominant relationship among ecosystem services in Jiangxi province was synergy; thus synergy mostly occurred in all ecosystem services except for food production from 1995 to 2015. However, during the 1995-2000 period, trade-offs mainly existed in both food production and waste treatment. The proportion of synergy greatly increased in the 2000-2015 period, and the synergistic relationship between waste treatment and other ecosystem services increased. However, the trade-off relationship between food production and other ecosystem services still has not improved, which should be concerned in the future. Changes in the percentage share of cropland showed a declining trend; thus, the potential risk of cropland loss should be monitored.

An effective strategy for boosting photoinduced charge separation of Ag3PO4 by BiVO4 with enhanced visible light photodegradation efficiency for levofloxacin and methylene blue.

In this paper, a Z-scheme Ag3PO4/BiVO4 photocatalyst was successfully prepared by precipitation-deposition method. The Ag3PO4/BiVO4 composite exhibited enhanced photocatalytic activity and recyclability for levofloxacin and methylene blue degradation under visible light irradiation. In the Ag3PO4/BiVO4-0.4 system, up to 92.44% of the levofloxacin molecules can be decomposed within 180 min and the photocatalytic degradation efficiency can maintain at 92.02% for methylene blue after recycled for 5 times. The enhanced photocatalytic activity of Ag3PO4/BiVO4 heterojunctions could be mainly attributed to the fabrication of hetero-structure between BiVO4 and Ag3PO4. The photogenerated electron-hole pair separation was effectively enhanced based on the photocurrent, electro-chemical impedance spectra and photoluminescence data. Furthermore, the electrons transfer from photoinduced BiVO4 to Ag3PO4 and the visible light harvesting efficiencies were significantly increased due to the BiVO4 hybridization. The ·OH was the main oxidative species in the Ag3PO4/BiVO4 system for the methylene blue decomposition. Finally, a purposed photocatalytic mechanism for methylene blue degradation was discussed in detail on the basis of experimental results.

The complete chloroplast genome sequence of Thymus mongolicus (Labiatae), a special spice plant.

Thymus mongolicus is well-known spice plant and resource of traditional Chinese herbal medicine, belonging to the Thymus of the Labiatae family. In this study, the whole chloroplast genome of the T. mongolicus was sequenced, assembled and annotated, which contains 134 unique genes, including 89 protein-coding genes, 37 tRNA genes and 8 rRNA genes. A maximum likelihood phylogenetic tree based on 21 complete chloroplast genomes revealed that T. mongolicus is closely related to Mentha genus. The chloroplast genome could be used for species, varieties and medicinal materials identification, genetic engineering and Labiatae germplasm resources protection.

Engineering the mechanical properties of CNT/PEEK nanocomposites.

Poly-ether-ether-ketone (PEEK) was deeply investigated as a composite matrix because of its outstanding mechanical properties and thermostability. However, the performance improvement of fiber-reinforced PEEK composites was moderate according to a great number of experimental investigations. An insightful understanding of the deformation and interfacial failure in the PEEK composite is needed to guide the future fabrication of high-performance PEEK plastics. In this paper, Molecular Dynamics (MD) simulation was employed to evaluate the mechanical properties of carbon nanotube (CNT) reinforced PEEK nanocomposites. It was found that the weak interface between CNTs and the PEEK matrix leads to the flaws in the CNT/PEEK nanocomposite. A CNT-functionalization strategy was used to introduce H-bonds between CNTs and the PEEK matrix, improving the overall mechanical performance of the CNT/PEEK nanocomposite. Numerical examples validate that the addition of amino groups on CNTs can significantly improve the interfacial failure shear stress and elastic modulus of the CNT/PEEK nanocomposites. This mechanism study provides evidence and a theoretical basis to improve the mechanical performance of fiber-reinforced PEEK for lightweight structures in advanced equipment.