Brain age has become an important analysis object in the diagnosis and mechanism research of neurodegenerative diseases. There is no consistent conclusion on whether major depression increases the ...brain age of patients, and few studies in this direction have been conducted in the Chinese population. In this paper, a REST-meta-MDD (resting-state functional magnetic resonance imaging dataset of major depressive disorder) dataset collected from 25 hospitals in China was used to construct a convolutional neural network model based on high-resolution T1-weighted three-dimensional magnetic resonance images of brain structures to predict the brain age of patients and calculate the difference from the actual age. The mean absolute error and correlation coefficients of the final results were 3.16 and 0.93, and the mean brain age of the patients with major depression increased by 3.94 years compared with the healthy group, further confirming that major depression accelerates brain aging, and the severity of the disease
The current problems of the low digital upgrading of rural e-commerce, single marketing method and high homogeneous competition will seriously hinder the development of rural e-commerce and rural ...revitalization. Therefore, finding how to guide the digital upgrading of rural e-commerce will be a key step in achieving rural revitalization and common prosperity. Based on 1387 Zhejiang rural e-commerce digital upgrading questionnaires, this paper analyzes willingness regarding rural e-commerce digital upgrading and its influencing factors using planned behavior theory and structural equation modeling. The findings show that (1) behavioral attitudes are the main influencing factors of upgrading willingness, and subjective norms are secondary influencing factors; (2) in terms of the behavioral attitudes of rural e-merchants, the greater the proportion of their online sales or the higher the proportion of online income, the better behavioral attitudes formed on this basis can promote the willingness to digitally upgrade rural e-merchants; (3) in terms of subjective norms, when rural e-merchant subjects perceive that the increased local participation in e-merchant association is too large or online income tends to saturate the total income, the more subjective norms can influence their willingness to digitally upgrade.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hydration plays a crucial role in cement composites, but the traditional methods for measuring hydration heat face several limitations. In this study, we propose a machine learning-based approach to ...predict hydration heat at specific time points for three types of cement composites: ordinary Portland cement pastes, fly ash cement pastes, and fly ash-metakaolin cement composites. By adjusting the model architecture and analyzing the datasets, we demonstrate that the optimized artificial neural network model not only performs well during the learning process but also accurately predicts hydration heat for various cement composites from an extra dataset. This approach offers a more efficient way to measure hydration heat for cement composites, reducing the need for labor- and time-intensive sample preparation and testing. Furthermore, it opens up possibilities for applying similar machine learning approaches to predict other properties of cement composites, contributing to efficient cement research and production.
Crack-induced damage significantly affects the chloride transport mechanism in cementitious materials. To quantitatively evaluate the crack effects, a coupled model was proposed in this paper for ...saturated cement paste with various uniaxial tensile damage. First, the 3D microstructure of hydrating cement paste was simulated based on a voxel-based hydration model, and its damaged spatiotemporal distribution under uniaxial tensile stress was simulated using a finite-element model. Based on the damaged cement paste, an electrical Modelling framework was presented to simulate the chloride transport. The results show that the damage spatiotemporal distribution in saturated cementitious materials with uniaxial tensile and its chloride transport evolution can be successfully modelled using the self-created model and coupled method. the damage of cementitious material is an accumulation process of cracks spread over the main crack. During the process, the crack connectivity and crack width affect chloride transport and its fracture-volume threshold value is 1.40%. Compared to studies published, the coupled model could well simulate chloride transport in saturated cementitious materials with uniaxial tensile damage.
Diffusion and convection are the main factors affecting chloride ion transport in unsaturated cementitious materials. In this study, capillary salt absorption experiment and steady-state migration ...experiment were used to investigate the chloride ion migration in unsaturated concrete, and a modified chloride ion diffusion-convection model was established for concrete considering curing age, initial water saturation and the combined effect of chloride ion. The results show that the chloride ion migration in unsaturated concrete can be divided into six stages: safety stage, initial stage, convection stage, deceleration stage, diffusion stage and stablilization stage, the chloride ion binding coefficient is approximately linear with the initial saturation, and the concrete with fly ash content of 40% or sand content of 60% has the best blocking effect on chloride ion migration.
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•It is found that concrete containing 40% fly ash or 60% sand has the best effect on preventing chloride transport.•A convection-diffusion model for chloride transport is in good aggreement with the experimental results.•The relation between the chloride binding coefficient and the initial saturation degree is figured out.
Particulate emissions from the combustion of diesel have always been the main concern, especially in recent years, with continuously stringent particulate emission regulation for diesel engines. To ...alleviate the problem, biodiesel has been received great attention because of its being environment-friendly, widely available and renewable. The application of biodiesel in diesel engines changes the combustion process, thus varies physicochemical property of the particulate matter (PM) formed, which in turn influences the oxidative reactivity of soot particles. In view of this, it is particularly important to analyze soot particles from the diesel engine fueled with biodiesels. This review focus on the effects of biodiesels on the physicochemical properties of soot particles, such as surface morphology, nanostructure, active surface area, element composition, elemental and organic carbon contents, surface functional groups, sp2 and sp3 hybridizations, etc. The impact of engine operating conditions (i.e. engine load, engine speed, fuel injection timing, fuel injection pressure, exhaust gas recirculation, etc.) on characteristics of soot particles from diesel engines powered by biodiesel is also discussed. Whereafter, the relationships between soot physicochemical characteristics and soot oxidative reactivity are reviewed. Finally, the main conclusions are outlined as well as the proposed research work in the future.
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•Biodiesel production and fuel properties are introduced.•Effect of biodiesel on diesel soot physicochemical properties is thoroughly detailed.•Correlation of soot properties with its oxidative reactivity is completely analyzed.•Biodiesel blending elevates diesel soot reactivity to favor DPF regeneration.
Severe fever with thrombocytopenia syndrome virus (SFTSV), which can cause hemorrhagic fever-like illness, is a newly discovered bunyavirus in China. The pathogenesis of SFTSV infection is poorly ...understood. However, it has been suggested that immune mechanisms, including cytokines and chemokines, play an important role in disease pathogenesis. In the present study, we investigated host cytokine and chemokine profiles in serum samples of patients with SFTSV infection from Northeast China and explored a possible correlation between cytokine levels and disease severity.
Acute phase serum samples from 40 patients, diagnosed with SFTSV infection were included. Patients were divided into two groups--severe or non-severe--based on disease severity. Levels of tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, interleukin-6, interferon (IFN)-γ, IFN- γ-induced protein (IP)-10 and RANTES were measured in the serum samples with commercial ELISAs. Statistical analysis showed that increases in TNF-α, IP-10 and IFN-γ were associated with disease severity.
We suggest that a cytokine-mediated inflammatory response, characterized by cytokine and chemokine production imbalance, might be in part responsible for the disease progression of patients with SFTSV infection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Microcracking induced by mechanical damage and moisture conditions both significantly modify the transport paths of aggressive species in cementitious materials. This study proposes a microscopic ...model to evaluate the coupling effects of microcracks and moisture conditions on gas permeability in cementitious materials accounting for its heterogeneous microstructure. The 3D microstructure of hydrating cement paste was simulated using a voxel-based hydration model, based on which the fracture process of cement paste under the uniaxial tensile loading was simulated using a finite element model. Subsequently, treating the damaged cement paste with various damage degrees as input, a lattice Boltzmann modelling framework was present to mimic the gas permeability of partially saturated cement paste considering the moisture distribution in its pore structure. Results indicate that gas permeability of cement paste with a lower water-to-cement ratio is more sensitive to the damage and the relative gas permeability is increased with the increase of damage degree. With the increasing water saturation level, the permeation paths for gas in cement paste are declined, while the air-filled microcracks as permeation paths are not significantly influenced. At a given damage degree, the increasing water saturation level leads to an increase in the relative gas permeability.
Interface bonding between calcium silicate hydrate (C–S–H) and epoxy is of critical importance for C–S–H/epoxy composites that are extensively utilized in the civil engineering, and yet it is ...susceptible to saline solution or elevated temperature. Herein, molecular dynamics is applied to explore the debonding mechanisms of epoxy from C–S–H surface under the coupling effect of water, ions, and temperature. Aqueous environment is the prerequisite for temperature and ions to influence interface bonding. At dry state, temperature elevation promotes the structure relaxation of C–S–H/epoxy interface, which optimizes the coordination structure at interface and increases interface energy. At wet state, on the contrary, temperature elevation aggravates the weakened effect of water molecules on interface bonding. The dynamics of epoxy molecules changes from the feature of solid state into fluid state. Water molecules and Na+ act in the same way at the interface. Both compete for active sites of epoxy molecules and C–S–H surface, which interferes the formation and stability of the bonds between C–S–H and epoxy molecules. As compared with water molecules, ions play larger roles in weakening interface bonding.
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