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Nanomaterials has been widely adopted in asphalt binder modification in pavement engineering. Considering the advantage of nano-Al2O3 in high-temperature resistance and chemical stability, this study investigated the feasibility of the nano-Al2O3 used in asphalt modification in terms of performances and mechanisms. The impact of the nano-Al2O3 content on modified asphalt binder's pavement performance was analyzed via aging resistance, low temperature performance, high temperature performance, and bonding performance using various tests (e.g. DSR test, BBR test, RTFOT test, and BBS test). Results showed that the nano-Al2O3 is capable of improving base asphalt's aging resistance, high temperature performance and bonding performance, while bringing an insignificant adverse impact on performance at low temperatures simultaneously. Moreover, modification mechanisms of the asphalt binder under the modification of nano-Al2O3 were revealed from a view of functional groups and molecular characteristics via Gel permeation chromatography (GPC) tests and Fourier transform infrared spectroscopy (FTIR) tests. According to the result, modification of base asphalt binder by nano-Al2O3 belongs to physical blended and inhibits the growth of sulfoxide groups during the aging process. Meanwhile, the nano-Al2O3 increases the base asphalt binder's molecular weight based on LMS percentage, number-average and weight-average. [ABSTRACT FROM AUTHOR]

To evaluate the tunneling effect of the earth pressure balance(EPB) shield in typical strata in Nanchang, China, a case study is conducted on a shield tunnel from Shengjinta station to Liuyanjing station. The evolution patterns of the main tunneling parameters of the EPB shield in full-section gravel sandstone stratum, full-section argillaceous siltstone, and composite sand-rock strata are investigated. Then, some characteristic parameters of the stratigraphic boreability including penetration degree, field penetration index, and tunneling specific energy are introduced to establish the relationships between the investigated key tunneling parameters. On this basis, the stratigraphic boreability of these three types of strata is evaluated. The research results indicate the following: (1) The main tunneling parameters are stable relatively when tunneling in gravel sandstone and argillaceous siltstone strata. The total thrust and the rotation speed of the cutterhead increase considerably in the composite sand-rock strata. (2) The cutterhead torque decreases gradually when shield tunnels from composite sand-rock strata to argillaceous siltstone strata. There is a satisfied positive linear relationship between the cutterhead torque and the total thrust in the argillaceous siltstone strata. (3) The value and oscillation of the penetration degree decline obviously when the shield tunnels from gravel sandstone to argillaceous siltstone strata. There are similar distributed characteristics of the field penetration index in the composite sand-rock strata and argillaceous siltstone strata but exhibit an opposite variation trend. Nevertheless, the tunneling specific energies of shield in these three strata are close to each other. (4) Significant correlations between the field penetration index and the penetration degree are observed in both gravel sandstone and composite sand-rock strata, but the correlation is weak in argillaceous siltstone strata. (5) The shield has a highest penetration degree and lowest field penetration index and tunneling specific energy in gravel sandstone strata, indicating the best tunneling effect of EPB shield in such strata. (6) On the whole, the gravel sandstone strata and the intermediately-weathered argillaceous siltstone strata show a better boreability than composite sand-rock strata. [ABSTRACT FROM AUTHOR]

High silicon dioxide content enables as a cement substitute. This study explored recycling RHA and RAP in cement stabilised macadam (CSM) to produce a pavement base material. Laboratory experiments covering strength, flexibility, shrinkage, and resistance to temperature variation were conducted on CSM with RAP (40% by weight of natural aggregates) and RHA at 0%, 20%, 40%, 60%, and 80% weight of cement. The results indicated that the compressive strength, resilient modulus, and tensile strength of CSM increased with curing time while the increasing rate and strength after curing decreased with the addition of RHA. The resistance to thermal changes, moisture loss, and the freeze-thaw cycle could be maintained by replacing 20 wt.% (or lower content) cement with RHA. These findings suggest that replacing 20 wt.% of cement with RHA and 40 wt.% of natural aggregates with RAP can generate qualified and environmental pavement base material. [ABSTRACT FROM AUTHOR]

Thermal and photothermal catalytic selective oxidation of isobutane to methacrylic acid (MAA) are comparatively studied over a keggin-type Cs2.9Cu0.34V0.49PMo12O40 heteropolyacid acid. An introduction of light was observed to enhance both the i-C4H10 conversion and the MAA selectivity, and consequently the MAA formate rate, particularly at low temperatures. Characterization results show that oxidation of methacrolein (MAL) to MAA is the rate-limiting step while UV light illumination promotes the oxidation of σ-bonded MAL with OH groups to σ-bonded MAA on the catalyst surface. These results demonstrate a synergistic effect of thermal catalysis and photocatalysis in selective oxidation of isobutane to MAA, which suggests photothermal catalysis as a promising strategy to catalyze the selective oxidation of higher hydrocarbons at relative mild reaction conditions. [ABSTRACT FROM AUTHOR]

Due to COVID-19, online education has become an important tool for teachers to teach students. Also, teachers depend on a multimedia teaching system (platform) to finish online education. However, interacted images from a multimedia teaching system may suffer from noise. To address this issue, we propose a lightweight image denoising network (LIDNet) for multimedia teaching systems. A parallel network can be used to mine complementary information. To achieve an adaptive CNN, an omni-dimensional dynamic convolution fused into an upper network can automatically adjust parameters to achieve a robust CNN, according to different input noisy images. That also enlarges the difference in network architecture, which can improve the denoising effect. To refine obtained structural information, a serial network is set behind a parallel network. To extract more salient information, an adaptively parametric rectifier linear unit composed of an attention mechanism and a ReLU is used into LIDNet. Experiments show that our proposed method is effective in image denoising, which can also provide assistance for multimedia teaching systems. [ABSTRACT FROM AUTHOR]

Background: Microvascular invasion (MVI) is an independent detrimental risk factor for tumor recurrence and poor survival in hepatocellular carcinoma (HCC). Competitive endogenous RNA (ceRNA) networks play a pivotal role in the modulation of carcinogenesis and progression among diverse tumor types. However, whether the ceRNA mechanisms are engaged in promoting the MVI process in patients with HCC remains unknown. Methods: A ceRNA regulatory network was constructed based on RNA‐seq data of patients with HCC from The Cancer Genome Atlas (TCGA) database. In total, 10 hub genes of the ceRNA network were identified using four algorithms: "MCC," "Degree," "Betweenness," and "Stress." Transcriptional expressions were verified by in situ hybridization using clinical samples. Interactions between ceRNA modules were validated by luciferase reporting assay. Logistic regression analysis, correlation analysis, enrichment analysis, promoter region analysis, methylation analysis, and immune infiltration analysis were performed to further investigate the molecular mechanisms and clinical transformation value. Results: The ceRNA regulatory network featuring a tumor invasion phenotype consisting of 3 long noncoding RNAs, 3 microRNAs, and 93 mRNAs was constructed using transcriptional data from the TCGA database. Systemic analysis and experimentally validation identified a ceRNA network (PVT1/miR‐1258/DUSP13 axis) characterized by lipid regulatory potential, immune properties, and abnormal methylation states in patients with HCC and MVI. Meanwhile, 28 transcriptional factors were identified as potential promotors of PVT1 with 3 transcriptional factors MXD3, ZNF580, and KDM1A promising as therapeutic targets in patients with HCC and MVI. Furthermore, miR‐1258 was an independent predictor for MVI in patients with HCC. Conclusion: The PVT1/DUSP13 axis is significantly associated with MVI progression in HCC patients. This study provides new insight into mechanisms related to lipids, immune phenotypes, and abnormal epigenetics in oncology research. [ABSTRACT FROM AUTHOR]