An effective finite difference scheme is considered for solving the time fractional sub-diffusion equation with Neumann boundary conditions. A difference scheme combining the compact difference ...approach the spatial discretization and L1 approximation for the Caputo fractional derivative is proposed and analyzed. Although the spatial approximation order at the Neumann boundary is one order lower than that for interior mesh points, the unconditional stability and the global convergence order O(τ2-α+h4) in discrete L2 norm of the compact difference scheme are proved rigorously, where τ is the temporal grid size and h is the spatial grid size. Numerical experiments are included to support the theoretical results, and comparison with the related works are presented to show the effectiveness of our method.
Double-arrowed auxetic (DAA) structures with a negative Poisson's ratio have recently drawn increasing attention. This paper deduces the empirical formula of critical impact velocity to characterize ...the deformation modes of the DAA structures in two in-plane directions. A method is proposed to construct a theoretical model for predicting the dynamic crushing strength of DAA structure. The theoretical model is validated by numerical results to be sufficiently accurate to predict the dynamic crushing strength. It is also found that the dynamic crushing strength is only related to the relative density and impact velocity.
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•An empirical formula of critical impact velocity is deduced.•A theoretical model is proposed to predict the dynamic crushing strength.•Theoretical predictions are validated by numerical results.
A new kind of chiral zirconium based metal-organic framework, l-Cys-PCN-222, was synthesized using l-cysteine (l-Cys) as a chiral modifier by a solvent-assisted ligand incorporation approach and ...utilized as the chiral stationary phase in the capillary electrochromatography system. l-Cys-PCN-222 was characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption, circular dichroism spectrum, zeta-potential and so on. The results revealed that l-Cys-PCN-222 had the advantages of good crystallinity, high specific surface area (1818 m
g
), thermal stability and chiral recognition performance. Meanwhile, the l-Cys-PCN-222-bonded open-tubular column was prepared using l-Cys-PCN-222 particles as the solid phase by 'thiol-ene' click chemistry reaction and characterized by scanning electron microscopy, which proved the successful bonding of l-Cys-PCN-222 to the column inner wall. Finally, the stability, reproducibility and chiral separation performance of the l-Cys-PCN-222-bonded OT column were measured. Relative standard deviations (RSD) of the column efficiencies for run-to-run, day-to-day, column-to-column and runs were 1.39-6.62%, and did not obviously change after 200 runs. The enantiomeric separation of 17 kinds of chiral compounds including acidic, neutral and basic amino acids, imidazolinone and aryloxyphenoxypropionic pesticides, and fluoroquinolones were achieved in the l-Cys-PCN-222-bonded OT column. These results demonstrated that the chiral separation system of the chiral metal-organic frameworks (CMOFs) coupled with capillary electrochromatography has good application prospects.
In coastal waters, particulate metals constitute a substantial fraction of the total metals; however, the prevalent water quality criteria are primarily based on dissolved metals, seemingly ...neglecting the contribution of particulate metals. Here we developed a method to quantify the toxicity risk of particulate metals, and proposed a way to calculate modifying factors (MFs) for setting site-specific criteria in turbid waters. Specifically, we used a side-by-side experimental design to study copper (Cu) bioaccumulation and toxicity in an estuarine clam, Potamocorbula laevis, under the exposure to “dissolved only” and “dissolved + particulate” 65Cu. A toxicokinetic-toxicodynamic model (TK-TD) was used to quantify the processes of Cu uptake, ingestion, assimilation, egestion, and elimination, and to relate mortality risk to tissue Cu. We find that particulate Cu contributes 40–67% of the Cu bioaccumulation when the suspended particulate matter (SPM) ranges from 12 to 229 mg L–1. The Cu-bearing SPM also increases the sensitivity of organisms to internalized Cu by decreasing the internal threshold concentration (C IT) from 141 to 76.8 μg g–1. MFs were derived based on the TK-TD model to consider the contribution of particulate Cu (in the studied SPM range) for increasing Cu bioaccumulation (MF = 1.3–2.2) and toxicity (MF = 2.3–3.9). Water quality criteria derived from dissolved metal exposure need to be lowered by dividing by an MF to provide adequate protection. Overall, the method we developed provides a scientifically sound framework to manage the risks of metals in turbid waters.
The primary objective of this paper is to address the inherent biases in the calculation of carbon emissions trading (CET) and foster the development of green innovation. By employing panel data from ...carbon emission trading pilots, the spatial Durbin model (SDID) is applied to assess the impact of CET on corporate environmental responsibility. By integrating CET and corporate environmental responsibility within a unified framework, this paper presents a novel analysis of the influence of environmental regulations on corporate environmental responsibility at the micro-level. Additionally, this study examines the spatial spillover effect of CET, thereby rectifying estimation biases. The model validation results indicate statistical significance below the 1 % level. The findings of this research reveal that it analyses the specific channels through which CET influences corporate environmental responsibility, providing insights that address the limitations of previous studies in mechanism analysis.
Paper-based substrates have been increasingly attractive in flexible electronics technology as flexible support substrates due to their advantages of availability, environmental friendliness (as ...disposable, degradable, and renewable materials), and foldability. Hereby, a facile method for installation of p-type and n-type semiconductor legs in the thickness direction of a paper substrate was established. A transparent paper-based thermoelectric generator prototype by impregnating the paper with resin was then fabricated. The resulting transparent paper-based thermoelectric generator with 10 thermocouples showed excellent mechanical flexibility. The generator maintained a maximum voltage and an output power of ∼8.3 mV and ∼10 nW, respectively, at a temperature difference of 35 K after 1000 bending cycles. This work offers a promising strategy for the development of paper-based thermoelectric generators that are adaptable to a wide variety of complex curved surface heat source. Therefore, the heat recovery efficiency in both human and natural environments can be greatly improved.
Harvesting solar energy for catalytic conversion of CO2 into valuable chemical fuels/feedstocks is an attractive yet challenging strategy to realize a sustainable carbon-cycle utilization. ...Homogeneous catalysts typically exhibit higher activity and selectivity as compared with heterogeneous counterparts, benefiting from their atomically dispersed catalytic sites and versatile coordination structures. However, it is still a “black box” how the coordination and electronic structures of catalysts dynamically evolve during the reaction, forming the bottleneck for understanding their reaction pathways. Herein, we demonstrate to track the mechanistic pathway of photocatalytic CO2 reduction using a terpyridine nickel(II) complex as a catalyst model. Integrated with a typical homogeneous photosensitizer, the catalytic system offers a high selectivity of 99% for CO2-to-CO conversion with turnover number and turnover frequency as high as 2.36 × 107 and 385.6 s–1, respectively. We employ operando and time-resolved X-ray absorption spectroscopy, in combination with other in situ spectroscopic techniques and theoretical computations, to track the intermediate species of Ni catalyst in the photocatalytic CO2 reduction reaction for the first time. Taken together with the charge dynamics resolved by optical transient absorption spectroscopy, the investigation elucidates the full mechanistic reaction pathway including some key factors that have been often overlooked. This work opens the “black box” for CO2 reduction in the system of homogeneous catalysts and provides key information for developing efficient catalysts toward artificial photosynthesis.
•Raman scattering coefficient of PO4-tetrahedron is achieved by calibration of NMR.•Quantification of Raman analysis of phosphorus structure is initially realized.•Structural behavior of phosphorus ...in glass is clarified by quantification analysis.
The phosphorus structures in CaO–SiO2–P2O5 glasses were analyzed by Raman spectroscopy and integral Raman intensities of PO4-tetrahedrons were calibrated by 31P MAS-NMR spectroscopy. Spectral results showed the presence of Q0(P) and Q1(P), and calculated values of Raman scattering coefficients of Q0(P), Q1(P) units were 1 and 0.576, respectively. Good agreement between experimental and theoretical values of non-bridging oxygen number per coordinated atom indicated the reliability of evaluating Raman scattering coefficients of Qn(P). Quantitative Raman analysis indicated that CaO exerted stronger ability to depolymerize PO4-tetrahedrons rather than SiO4-tetrahedrons with increasing basicity under the condition of higher degree of polymerization. P2O5 added to silicate melt could cause an increase in amount of Q2(Si), Q3(Si) and Q4(Si) units due to stronger stability of P–O–Ca linkages than that of Si–O–Ca linkages. Moreover, P5+ ions could be partly replaced with Si4+, forming Q1(Si+P) and Q2(Si+P) units.
This study aimed to evaluate the roles of pathological disorders in Internet addiction disorder and identify the pathological problems in IAD, as well as explore the mental status of Internet addicts ...prior to addiction, including the pathological traits that may trigger Internet addiction disorder.
59 students were measured by Symptom CheckList-90 before and after they became addicted to the Internet. A comparison of collected data from Symptom Checklist-90 before Internet addiction and the data collected after Internet addiction illustrated the roles of pathological disorders among people with Internet addiction disorder. The obsessive-compulsive dimension was found abnormal before they became addicted to the Internet. After their addiction, significantly higher scores were observed for dimensions on depression, anxiety, hostility, interpersonal sensitivity, and psychoticism, suggesting that these were outcomes of Internet addiction disorder. Dimensions on somatisation, paranoid ideation, and phobic anxiety did not change during the study period, signifying that these dimensions are not related to Internet addiction disorder.
We can not find a solid pathological predictor for Internet addiction disorder. Internet addiction disorder may bring some pathological problems to the addicts in some ways.
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