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The drilling-hammer method is adopted for the breaking over submerged reefs in waterway regulation engineering. However, rocks with pre-drilled holes are highly susceptible to the repetitive impacts from drop hammers or drilling equipment. Exploring the dynamic responses and failure behaviors of drilled-hole rocks under repetitive impacting is important for promoting implementation of this technique. In this study, the repetitive impacting tests were conducted on the drilled rocks by the split Hopkinson pressure bar to investigate the rock bearing capacity, deformation property, failure behavior, and energy evolution. The results indicate that the presence of pre-drilled holes and the decreasing loading rates attenuate the bearing capacity of rocks subjected to repetitive impacting. In contrast, the rock deformation capacity is impacted subtly by the impact loading rate and increases with the number of impacts and borehole size. The drilled rock failure occurred with the prevalence of intergranular fractures; subsequently, the proportion of transgranular fractures increased, contributing to the loading rate-dependent bearing capacity. The inverted S-shaped damage evolution curve was assessed using the inverted logistic growth model. The specimen absorbed few incident energies for fracture generation and propagation, and the rock with a larger drill size displays higher energy utilization and larger fragments. • Illustrated the influences of repetitive impacting on the bearing capacity and deformability of pre-cracked hole rocks. • Revealed the failure behavior and fracture mechanism of pre-cracked hole rocks under repetitive impacting. • Depicted the damage evolution of pre-cracked hole rocks under repetitive impacting by the inverted logistic growth model. • Investigated the dynamic energy dissipation of pre-cracked hole rocks under repetitive impacting. [ABSTRACT FROM AUTHOR]

• Proposed a key bone extraction network based on YOLOv5. • The GRU and Unet networks are integrated to achieve high-quality segmentation of key bones. • The proposed two-stage key bone segmentation was verified by experiments. • Evaluate the accuracy of partial baseline target detection network, semantic segmentation network and the proposed method. Automatic segmentation of hand bone X-ray images is an important process in skeletal bone age assessment (BAA). The segmentation process is extremely difficult and complicated due to the complex structure and tiny size of hand bone features, which may lead to inaccurate feature localization and incomplete segmentation. A two-stage segmentation method is proposed in this paper. In the first stage, the OSA-YOLOv5 network is used to extract hand bones, and in the second stage, GRU-UNet is used to separate extracted hand bones. The hand bone X-ray dataset consists of a mixed dataset of 1000 left-hand bone X-ray images of adolescents from licenced local hospitals and 1000 left-hand bone X-ray images from the RSNA public dataset. The training efficiency of the OSA-YOLOv5 network is 28 % higher than that of the traditional network, and the proposed network exhibits with a higher extraction accuracy. The segmentation accuracy of the GRU-Unet segmentation model 14.70 % higher than that if Unet. The spatial sequence features with spatial rules are found to have a positive correlation in GRU-Unet. Experimental results show that the proposed segmentation method has good generalization and robustness, which provides a good foundation for subsequent BAA. [ABSTRACT FROM AUTHOR]

The cracked chevron notched semi-circular bend (CCNSCB) method has been utilized in split Hopkinson pressure bar (SHPB) tests to measure the rock dynamic mode I fracture toughness. However, the measuring principle has never been thoroughly evaluated. In this study, a three-dimensional discrete element method has been employed to numerically investigate the dynamic fracture mechanism of CCNSCB specimens in SHPB testing considering different loading rates and supporting spans. Our results show that, even if the dynamic force balance can be efficiently satisfied, the conventional quasi-static analysis can still be questionable. For specimens with smaller supporting spans, the developing crack fronts are rather curved during the loading process, and the critical crack length is highly dependent on the loading rates. While for specimens with a large supporting span, the crack profiles are less affected and the critical crack fronts are finely confined within the chevron ligament with few undesirable damages. Thus, the CCNSCB method with a larger supporting span appear to be sound in the SHPB tests for measuring dynamic mode I fracture toughness of rocks. [ABSTRACT FROM AUTHOR]

Abstract: We performed systematic first principles calculations based on density functional theory to probe the energetics of dissociation of water molecules on small (TiO2) n (n =3, 4, 6, 8, and 10) clusters. We found that the (TiO2) n clusters have a strong ability to adsorb water molecules and the dissociative adsorption of water molecules on the surface of (TiO2) n clusters with a three step process is irreversible, size-dependent and energetically more favorable than the same on the surfaces of titanium oxide. Charged (TiO2) n cluster also have strong ability in H2O molecule splitting similar as neutral ones. The efficiency of water molecules dissociating on (TiO2) n cluster surface varies inversely with the cluster size due to the steric effect. Our results indicate a higher efficiency of small clusters of titanium oxide in dissociating water molecules than its low index surfaces of bulk terminated. [Copyright &y& Elsevier]

Abstract: Quantum mechanical calculations were carried out to determine the mechanisms for the superiority of the imidazolium acetate-based ionic liquids to the corresponding chloride-based ionic liquids. Our results indicate that the imidazolium cation can react with the acetate anion to generate a carbene, a highly reactive intermediate. The carbene produced then reacts with cellulose to facilitate its dissolution in the ionic liquid solvents in addition to the stronger hydrogen bonds formed between the acetate anion and the hydroxyl groups on cellulose. The mechanisms for the imidazolium cation and acetate anion reactions involve the initial ion pairing of the cation and anion via hydrogen bonding and electrostatic interactions. The hydrogen bond formed between the C2–H on the imidazolium cation and COO− of the anion facilitates the transfer of the H+ to the anion to form a carbene intermediate. [Copyright &y& Elsevier]

Abstract: Experience of light rail, metro and other urban rail transit schemes shows they can play a significant role in improving the attractiveness and quality of urban public transport. In terms of the high cost of rail transit systems, land value capture has drawn increasing attention as a result of its potential for funding public transport infrastructure. To evaluate its potential success, it is crucial to examine critically the impact of public transport on land value before approaching the question of land value capture. This paper considers how the introduction of a rail transit system can lead to land value changes using the extension to Sunderland of the Tyne and Wear Metro (UK) as a case study. Changes in land values, specifically residential land prices, have been investigated using residential property prices data from local newspapers. This paper presents a statistical analysis of residential property price change in the vicinity of Sunderland Metro stations together with the results on the significance of land value uplift associated with the Metro in Sunderland. The results are discussed in the context of previous studies of the Tyne and Wear Metro before the Sunderland extension was planned. The paper concludes with a discussion of the reasons for the results. [Copyright &y& Elsevier]

• Monitoring during the rare exposure period of the dike due to climatic conditions. • Spur dike greater impact on plankton diversity and physicochemical factors. • Planktonic community similarity in upstream–downstream of dike greater than dike type. • Co-occurrence network complexity for eukaryote is in longitudinal dike, prokaryote is in spur dike. • Flow velocity effect on planktonic community in aquatic environment around dike. To investigate the effects of the waterway regulation structures on the hydraulic characteristics, water physicochemical factors, and the planktonic community in the upper Yangtze River, this study was conducted in August and September of 2022 on two ecological dikes in the Chongqing section of the upper Yangtze River: the longitudinal dike and the spur dike. High-throughput sequencing technology was used to explore the differences in planktonic community structures upstream and downstream of the waterway regulation structures during the dry season, as well as their main influencing factors. The results showed that the dissolved oxygen increased significantly, and the turbidity and flow rate decreased significantly in downstream of dikes. The spur dike exhibited more pronounced changes in water quality and hydrodynamic factors compared to the longitudinal dike. The diversity index of phytoplankton, zooplankton, and fungi in the downstream of dikes were higher than those in the upstream, and the bacterial diversity index was higher than those of eukaryotes at each sampling site. The impact of the spur dike on the planktonic biodiversity index was greater than that of the longitudinal dike, as it alters flow velocity, turbidity, and dissolved oxygen. The major phyla of phytoplankton, zooplankton, and bacteria, including Cryptophyta (70.37–80.57 %), Mollusca (7.56–37.50 %), and Proteobacteria (48.53–55.92 %), had a higher relative abundance in upstream of dike, and their relative abundance in spur dike was higher than that in longitudinal dike. In contrast, the relative abundance of the major phylum of fungi, Ascomycota (37.15–56.85 %), showed an opposite trend in both dike-to-dike comparison and dike upstream-to-downstream comparison to the above three plankton. The analysis of the neutral community model indicated that the predominance of stochastic assembly processes in the planktonic community was higher in the longitudinal dike compared to the spur dike, and longitudinal dike demonstrated higher rates of planktonic migration and speciation compared to the spur dike. Flow rate, dissolved oxygen, and turbidity were the significance influencing factors on the planktonic community structure in the aquatic environment around dike. Differences in dike-related environmental factors result in greater interactions among prokaryotes in the spur dike, while eukaryotes exhibited a more complex network of relationships in the longitudinal dike. These findings can provide a theoretical basis for the protection of biodiversity and the construction of ecological waterways in the waterway regulation engineering area. [ABSTRACT FROM AUTHOR]

The current two-dimensional (2D) material based NH 3 sensors generally suffer from low response values and sluggish recovery dynamics, which is resulted from their inferior conductivity. Herein, high conductivity (0.045 S/m) of 2D hydrogen substituted graphyne (HsGY) nanosheets are successfully synthesized employing aqueous/organic interface method and using them for the first time for the detection of NH 3 at room temperature. The resultant gas sensing performance shows that the 2D HsGY nanosheets exhibit a high gas response value (4.9) to 100 ppm NH 3 and fast recovery time (108 s) at the room temperature. The NH 3 gas sensing mechanism is discussed by utilizing density functional theory (DFT) calculations. The present study provides novel gas sensing material for the development of high-performance room temperature NH 3 sensors. This study successfully synthesized two-dimensional hydrogen substituted graphyne (HsGY) nanosheets using an aqueous/organic interface method and applied them for the detection of NH 3 at room temperature for the first time. HsGY nanosheets exhibit excellent sensing performance towards NH 3 , due to their high conductivity and continuous thin gauze like morphology, which facilitates gas transport. [Display omitted] [ABSTRACT FROM AUTHOR]

• An oblique impact method using inclined cylinder specimens is employed in a split Hopkinson pressure bar (SHPB) apparatus modified with an axial pressure chamber to achieve the compression-shear loading in a combined static-dynamic mode. • Numerical simulations using both the finite element method and the discrete element method are conducted to assess the validity of this compression-shear specimen and to establish a new data processing method. • Experimental results highlight the combined effects of the loading rate and the axial confinement on the failure strength, fracturing mode and deformation characteristics of sandstone. The compression-shear behavior and failure mechanism of rocks under combined static-dynamic loading are of essential importance for mechanical characterization and construction safety in deep underground engineering applications. An inclined cylinder specimen is designed using a split Hopkinson pressure bar (SHPB) apparatus modified with an axial pressure chamber for laboratory studies. Specific issues on the validity of this compression-shear specimen that were not addressed previously have been numerically assessed involving the dynamic equilibrium of force and moment, stress uniformity, and interfacial friction effects. Experiments are conducted at different loading rates ranging from 500 to 4000 GPa/s and under axial pressures of 7, 21, 35, 49, and 63 MPa. Experimental results verify the dynamic equilibrium of inclined specimens in the axially constrained SHPB tests using pulse shaping techniques, which validates the data processing method newly proposed. Both the dynamic strength and total strength linearly increase with the loading rate. With the increasing pre-load ratio (ratio of the axial confining load to the unconfined compression strength of the tested material), the dynamic strength decreases, while the total strength increases and then keeps constant, where the turning point of the pre-load ratio approximates 0.7. High-speed photographs at a high loading rate illustrate that the increasing confinement can result in less shear but more tensile cracks. Particularly at a high confining condition, the inclined specimen fails by a feather-like shear fracture band where tensile secondary cracks extensively develop. The equivalent stress-strain relationships indicate the reinforcing effect of the confinement on the deformation and energy dissipation. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• In the early stage of cirrhosis, there seems to be a possibility of cirrhosis reversal. • The development of cirrhosis is related to the intestinal microbiota and activation of toll-like receptors (TLRs) pathways, which could regulate cell proliferation, apoptosis, expression of the hepatomitogen epiregulin, and liver inflammation. • In this paper, we first reviewed the dynamic change of intestinal microbiota and TLRs during cirrhosis progression. And further discussed the interaction between them and potential therapeutic targets to reverse early staged cirrhosis. • The interference of toll-like receptors (TLRs) and its intracellular signaling pathway can regulate the liver inflammatory response and cirrhosis process. • Drug treatment of intestinal dysbiosis and TLRs activation may slow cirrhosis progression. • With the further study of intestinal microbiota and TLRs on the progression of cirrhosis, it offers a new way of preventing and treating inflammatory response and fibrosis diseases. Cirrhosis is a progressive chronic liver disease caused by one or more causes and characterized by diffuse fibrosis, pseudolobules, and regenerated nodules. Once progression to hepatic decompensation, the function of the liver and other organs is impaired and almost impossible to reverse and recover, which often results in hospitalization, impaired quality of life, and high mortality. However, in the early stage of cirrhosis, there seems to be a possibility of cirrhosis reversal. The development of cirrhosis is related to the intestinal microbiota and activation of toll-like receptors (TLRs) pathways, which could regulate cell proliferation, apoptosis, expression of the hepatomitogen epiregulin, and liver inflammation. Targeting regulation of intestinal microbiota and TLRs pathways could affect the occurrence and development of cirrhosis and its complications. In this paper, we first reviewed the dynamic change of intestinal microbiota and TLRs during cirrhosis progression. And further discussed the interaction between them and potential therapeutic targets to reverse early staged cirrhosis. [ABSTRACT FROM AUTHOR]

• Stability criterion for underground cavern sidewall subject to flexural toppling is deduced. • A dynamic approach for analyzing the flexural-toppling of cavern sidewall is proposed. • Secondary stress field and failure process are considered in the evaluation. • Stresses of bedding planes are obtained via a new comprehensive approach. Flexural toppling is a crucial engineering issue for high sidewalls of underground powerhouse caverns in low stress regions, when a small angle between cavern axis and bedding planes is formed. In this study, a novel dynamic method is proposed for stability evaluation of a high sidewall subjected to flexural-toppling, by integrating our derived criterion, continuum modelling and microseismic (MS) data. First, by virtue of cantilever slab theory, a geo-mechanical model is defined for analysing the toppling rock strata exposed on the high sidewalls of underground caverns. The Rayleigh-Ritz method is then adopted to deduce the equation for potential energies of toppling rock strata. A criterion for assessing the stability of high sidewalls considering a secondary stress field can thus be derived from catastrophe theory. Subsequently, stresses acting on the bedding planes are numerically obtained by continuum modelling coupled with MS data. Finally, a quantitative stability evaluation methodology is presented for flexural-toppling in view of progressive failure, considering the influence of fractures along bedding planes. A practical case of flexural toppling failure is analysed to verify our proposed approach. Good agreements indicate that our proposed approach is reliable for quantitatively evaluating the stability of larger underground powerhouse caverns against flexural toppling. [ABSTRACT FROM AUTHOR]

• Rate-dependent cracking behaviors of single-flawed rock specimen under dynamic loading are numerically observed via DEM simulation. • Tensile wing cracks dominate specimen failure under low strain rate, while anti-wing cracks and shear cracks are prevalent under high strain rate. • Different initiation locations of tensile wing cracks are explained by stress filed visualization and theoretical analysis. • The initiation angles of tensile wing cracks are predicted via GMTS criteria, and the length of FPZ increases with increasing strain rate. This paper numerically investigated the rate-dependent progressive cracking behaviours of single-flawed rock specimens in split Hopkinson pressure bar (SHPB) tests. First, a 3D numerical SHPB system is established based on the discrete element method (DEM). By comparing with our laboratory experiments, micro-parameters of the DEM model are calibrated, which guarantees the reliability of the numerical simulations results. Via slice-cutting view, the inner and surface progressive cracking processes are explicitly revealed and compared, which compensates some defects in laboratory tests. Our numerical simulation results show that the progressive cracking behaviours of the single-flawed rock specimens exhibit evident rate dependence. Under low strain rates, tensile wing cracks dominate the entire cracking process, and only a few shear cracks appear during the post-peak stage. In contrast, under high strain rates, tensile wing racks are significantly suppressed, while anti-wing cracks and shear cracks are fully developed, leading to the final X-shaped failure modes. In addition, progressive cracking behaviours of the single-flawed rock specimens with different flaw inclination angles are assessed. Via stress field visualization and theoretical analysis, the different initiation locations of tensile wing cracks are explained. Furthermore, based on the generalized maximal tangential stress (GMTS) criteria, the fracture initiation angles of tensile wing cracks are predicted. The results show that the fracture initiation angles and the fracture process zone (FPZ) are significantly affected by the strain rate. The length of FPZ under dynamic loads is evidently longer than that under static loads, and the length of FPZ generally increases with an increasing strain rate, exhibiting evident rate dependence. [ABSTRACT FROM AUTHOR]

• Numerical modeling was performed to study dynamic mixed mode I/II fracture behavior of rocks. • Different mixed mode loading conditions and various loading rates were considered. • Dynamic mixed mode fracture of the specimens was mainly induced by tensile damages at the micro scale. • Mixed mode fracture resistance of rocks showed loading rate dependence. • A semi-analytical criterion could predict well the dynamic mixed mode fracture of rocks. Research on rock fracture behavior is usually limited to static mixed mode I/II fracture and static or dynamic mode I fracture. In this study, the notched semi-circular bend (NSCB) specimens with different notch inclination angles were introduced into the split Hopkinson pressure bar (SHPB) system to numerically investigate dynamic mixed mode I/II fracture behavior of cracked rocks. First, the feasibility and reliability of our discrete-element-method-based numerical system to model dynamic fracture behavior of rock were validated; then, the effects of different mixed mode loading conditions and various loading rates on the mixed mode fracture of NSCB specimens were studied. The dynamic mixed mode fracture of the specimens was found to be mainly induced by tensile damages at the micro scale. The results also showed the loading rate dependence of the mixed mode fracture resistance. Moreover, for the same increment of the loading rate, the dynamic mode I fracture toughness increases more than the dynamic mode II fracture toughness. Subsequently, the fracture resistance and fracture initiation angles observed in the modeling were compared with the theoretical predictions based on some brittle fracture criteria. It was demonstrated that a semi-analytical criterion could reproduce well the dynamic mixed mode fracture behavior of rocks. [ABSTRACT FROM AUTHOR]