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•Cubic-tetragonal interface in Ce-Zr solid solution was successfully synthesized.•The catalyst interface promoted the interaction between surface Mn and Ce species.•The catalyst ...interface improved catalytic performance for toluene oxidation.•Higher surface lattice oxygen concentration was obtained on the interfaces.
In this study, the CeO2-ZrO2 solid solutions with cubic-tetragonal interfaces were prepared by an urea hydrolysis method and a solvothermal method. Then they were used as the supports and Mn/Ce-Zr catalysts were prepared by impregnation method. The catalytic performance of the catalysts for toluene oxidation were evaluated by a steady-state measurement and compared with that of Mn/Ce-Zr-ss without the interfaces, in which the support was prepared by co-precipitation. The result was found that the catalyst interfaces apparently enhanced catalytic activity for toluene oxidation. The coexistence of cubic and tetragonal phases and their interfaces were confirmed by XRD and HRTEM. H2-TPR and XPS results indicated that the cubic-tetragonal interfaces led to stronger interaction between surface Mn and Ce species and higher concentration of lattice oxygen produced from the catalyst surface. DRIFT spectra revealed that the catalyst interface promoted the adsorption of toluene and the formation of key intermediates at low temperatures. These would be important factors that caused a higher activity of the catalyst with cubic-tetragonal interfaces. Moreover, the promoting role of the interfaces might be related to the morphology, surface area and interface components of Ce-Zr supports.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
It is widely understood that fiber-reinforced composite structures made with 'thinner plies' can exhibit better mechanical properties. To avoid the friction to fibers in the traditional mechanical ...method, a new two-stage pneumatic fiber spreading system was established. To better understand the lateral-spreading mechanism of the system and optimize the relevant control parameters, CFD models of hot-air jet and turbine spreader are built with the help of multi-block technology and Euler multiphase flow method. By characterizing the distribution of air velocities in the flow fields, the influences of the boundary conditions were evaluated and optimized. The simulation results match well with the experiments, and show the feasibility and effectiveness of the multi-block technology and Euler multiphase flow method. Under the guidance of the optimization results, carbon fiber bundles have been evenly and continuously spread from 8 to 48 mm.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Commercial development of natural gas hydrate, over 90% of which is found in fine-grained sediments worldwide, is of significance to energy structure, energy security, and global climate. One of the ...most critical physical parameters for hydrate exploitation is reservoir permeability, which directly affects the efficiency and economic feasibility of gas production. In this paper, hydrate morphologies and pore habits are identified in both natural cores and synthesized fine-grained specimens. Laboratory and field tests of permeability are summarized, and the dependence of permeability on various influencing factors is comprehensively discussed. Results show that the hydrate morphologies and pore habits are predominantly influenced by particle size, stress state, and geological conditions. They exist in the form of lenses, nodules, chunks, veins, and others within fine-grained sediments. The effective permeability is typically measured as larger than 1 millidarcy (mD) in laboratory tests, however, field tests have shown that it can range from 0.01 to 1 mD. There is a lack of effective permeability models that can be used in numerical simulations to predict gas production capacity. Furtherly, challenges to current research are analyzed and future research prospects are proposed. Developing new measurement techniques, bridging the gaps of different methods and scales, as well as establishing appropriate permeability models are needed for reservoir simulators to accurately predict gas production. Collaborative and comparative studies are needed to develop agreeable measurement methods and testing protocols to address the challenges of better understanding the permeability in hydrate-bearing fine-grained sediments.
•A comprehensive review of permeability in hydrate-bearing fine-grained sediments is conducted.•Hydrate morphologies and pore habits as well as other factors influencing the permeability are analyzed.•Research challenges and prospects of permeability in hydrate-bearing fine-grained sediments are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In order to study the damage mechanism of carbon fiber composite laminates, an experimental and numerical investigation has been carried out to study the dynamic perforation behaviors of composite ...plates subjected to low velocity impact. The numerical simulations of the progressive damage process for different plates under different impact energies are based on the Multi-Continuum Theory (MCT). 3D FE models with cohesive ply element was established, and the failure processes of the matrix component and the fiber component in the laminates were individually simulated based on MCT failure criterion. By introducing two parameters, the penetration limit and the perforation limit, the damage process of each plate was showed in the form of Energy profile diagram (EPD) which was used to compare the impact resistance abilities of three kinds of composite plates The simulation results were in good agreement with the experimental results. The results revealed that there is a greatest impact resistance in mixed lay-up plate. Compared to the 0-degree plates and the orthotropic plates, the damage strength of the mixed lay-up plate has increased by 252 % and 120 % respectively.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Phenol, an important bioactive substance in jujube fruit, is one of the most important indexes of fruit quality. In order to clarify the phenolic substance composition, content and ...distribution characteristics of different varieties of jujube fruits, this study measured and compared the content of total phenols, total flavonoids and phenolic substance composition in different parts of fruits of six jujube varieties, and combined with the principal component analysis, the results showed that: Fourteen phenolic substances were identified in the fruits of different jujube varieties, and proanthocyanidins, epicatechin, catechin and rutin were the main components, accounting for 58.60%, 16.08%, 13.56% and 5.57% of the total phenolic substances, respectively. The total phenolic and total flavonoid contents of jujube fruits of each variety were between 18.11 and 21.45 mg GAE/g DW and 10.56–20.25 mg RE/g DW, respectively, and the differences in the contents between the varieties were significant, and the contents of ‘Junzao’ and ‘Jinlingyuanzao’ were higher than those of other varieties.The phenolic content of different parts of jujube fruits showed spatial distribution differences, manifested as the total phenols, total flavonoids and their fractions of the peel were significantly higher than that of the pulp, while the content of the pulp near the kernel was significantly higher than that of other parts of the pulp, This study provides a theoretical basis for analysing the differences in phenolic substances in jujube fruits.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Nuclear magnetic resonance (NMR) is an effective method used for measuring and predicting the properties of methane hydrate (MH)-bearing sediments. In this work we present the results of MH-related ...interface evolution during the MH dissociation process obtained by X-ray computed tomography (CT) imaging technique. Some implications of interface evolution for the NMR-based property predictions are analysed based on the experimental measurements. The results show that the areas of MH surface and MH-brine interface decrease slowly in the early stage of dissociation, but turns to decrease rapidly in the later stage. A conceptual model for determining the NMR transverse surface relaxivity (ρ2) in the hydrate-bearing sediment is proposed by considering these changes of MH-related interface. Predictions based on this model show that the NMR transverse surface relaxivity and effective permeability are both influenced by the influencing weight and surface area proportions of the MH-brine surface and sand-brine surface.
•The changes in the hydrate-related interface with hydrate saturation was experimentally measured and analyzed.•An analytical model for determining the NMR transverse surface relaxivity in the hydrate-bearing media was proposed.•The implications of hydrate interface evolution to the NMR-based permeability predictions are illustrated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To overcome the limitations of the present grey models in spatial data analysis, a spatial weight matrix is incorporated into the grey discrete model to create the SDGM(1,1,m) model, and the ...L1-SDGM(1,1,m) model is proposed, considering the time lag effect to realize the simultaneous forecasting of spatial data. The validation of the SDGM(1,1,m) and L1-SDGM(1,1,m) models is achieved, and finally, the per capita energy consumption levels (PCECs) of 30 provinces in China from 2020 to 2025 is predicted using SDGM(1,1,m) with a metabolic mechanism. We draw the following conclusions. First, the SDGM(1,1,m) and L1-SDGM(1,1,m) models established in this paper are reasonable and improve forecasting accuracy while supporting interactive regional forecasting. Second, although SDGM(1,1,m) resembles the DGM(1,n) model, their modeling conditions and targets are different. Third, the SDGM(1,1,m) and L1-SDGM(1,1,m) models can be used to effectively analyze the spatial spillover effects within the selected modeling interval while achieving accurate predictions; notably, from 2010 to 2017, the PCECs of Inner Mongolia and Qinghai were most affected by spatial factors, while the PCECs of Jilin, Jiangxi, and other provinces were influenced little by spatial factors. Fourth, predictions indicate that the PCECs of most Chinese provinces will increase under the current grey conditions, while the PCECs of provinces such as Beijing are expected to decrease.
Permeability is critical to understand gas production behavior from hydrate reservoirs. The effects of particle size distribution and initial brine saturation on effective permeability of ...hydrate-bearing sediment during hydrate dissociation are poorly understood. In this study, X-ray CT imaging and Lattice Boltzmann simulations are combined to obtain a better understanding of sediment permeability changes during hydrate dissociation and the effects of particle size distribution and initial brine saturation. The results reveal that the dissociation of hydrate induced by depressurization starts from the part in contact with gas, causing a gradual increase in sediment effective permeability with decreasing hydrate saturation. When a critical hydrate saturation below 0.1 is reached, a sharper increase in permeability is found in sediments initially saturated with 50% brine than with 100% brine. To investigate the underlying relationship between hydrate morphology and sediment permeability, two topological parameters of an isolated hydrate cluster, equalivalent diameter and shape factor, are introduced. Phase topology analysis of hydrate clusters confirms that the partial water saturation method causes a more heterogeneous spatial distribution of hydrate at pore-scale. It also suggests that sediment with a narrower particle size distribution shows a faster increase in permeability and a more uniform hydrate morphology evolution with dissociation, no matter whether it is initially 50% or 100% brine saturated. A slower effective permeability increase and hydrate morphology evolution are achieved in initially 100% brine-saturated sediments, implying a more uniform dissociation of hydrate in pore space.
•The effects of particle size and initial brine saturation on permeability change during hydrate dissociation are explored.•Topology analysis confirms that the partial water saturation method causes heterogeneous distribution of methane hydrate.•Sediment permeability slowly increases with hydrate dissociation, followed by a sharp rise as hydrate saturation is below 0.1.•Sediment with a narrower particle size range shows a faster permeability rise and a slower morphology evolution of hydrate.•A more uniform dissociation of methane hydrate in pore space of initially 100% brine-saturated sediments is observed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cu/SSZ‐13 catalysts with different Cu loadings (1–5 wt.%) were prepared by conventional impregnation via a slow step‐dry process for the direct conversion of methane to methanol. Catalytic ...performance of the catalysts is found to depend on the Cu loading in both stepwise and continuous processes and 2 wt.% Cu presents the best performance. CuO nanoparticles, CuxOy clusters and monomeric CuOH+ species are found on Cu/SSZ‐13 based on HRTEM, HAADF‐STEM, DR UV‐vis and FTIR spectroscopies. The high coverage of CuO nanoparticles on 5 wt.% Cu/SSZ‐13 results in the loss of catalytic reactivity in spite of the existence of active CuxOy and CuOH+ sites. Besides, it is proposed that the formation of Cu2O22+ and Cu2O2+ active sites involves CuOH+ intermediates. We further found that improved catalytic performance in cyclic stepwise process involves the re‐dispersion of CuO nanoparticles and/or large clusters as well as the re‐oxidation of Cu(I) cations from self‐reduction of CuOH+ species.
Structure‐activity relationship: Formation of active sites over impregnated Cu/SSZ‐13 catalyst involves the re‐dispersion of CuO and re‐oxidation of Cu(I) species in methane‐to‐methanol reaction with water as oxidant.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Thyroid carcinoma (THCA) is a tumor commonly occurring in the endocrine system, and its incidence rate is increasing yearly. Anoikis is a type of cell death involved in the carcinogenesis process. ...This study aimed to investigate the prognosis and immune correlations of anoikis in THCA. Our study used several bioinformatics algorithms (co-expression analysis, univariate and multivariate Cox analysis) to screen anoikis-related genes (ARGs) to construct risk models. Through receiver operating characteristic (ROC) curve, nomogram, and independent prognostic analysis found that the constructed model had ideal predictive value for THCA. The consensus clustering method was used to divide ARG patterns into three subgroups, and there were significant differences in survival among the three subgroups. The CIBERSORT algorithm demonstrated strong correlations among immune infiltrating cells, prognostic genes, and risk scores. Univariate and multivariate Cox analysis showed that CDKN2A is an independent prognostic gene. Basic experiments (immunohistochemistry, qRT-PCR, etc.) showed that the expression levels of CDKN2A mRNA and protein were highly expressed in THCA, which was consistent with the results of bioinformatics analysis. In vitro, the knockdown of CDKN2A significantly inhibited the proliferation and migration of THCA cells. In summary, our study utilized eight ARGs to construct an accurate risk model. ARGs, especially CDKN2A, play a crucial role in the occurrence and development of THCA and can become potential targets for treating THCA patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
