•AASF pastes display a higher resistance to phosphoric acid than OPC regardless of pH.•AASF pastes exhibited an induction period during the phosphoric acid attack.•The degradation of OPC exposed to ...phosphoric acid can be described using Power law.•After 50 years (phosphoric acid, pH = 2.0), AASF pastes have a reduced DD by 70–80%.
High costs are currently involved in the repair and replacement of sewage concrete pipes due to the severe damage caused by the acid-rich aggressive environments of sewage and drainage wastewater. Although it is known that, a high concentration of phosphoric acid exists in some sewer pipes, very few studies have been focused on its impact on various cementitious materials. The purpose of this study is to experimentally investigate the resistance of alkali-activated slag/fly ash-based pastes and compare them to ordinary Portland cement-based pastes exposed to phosphoric acid with different pH values (pH = 2, 3 and 4) for a period of 150 days. The experimental results revealed that alkali-activated slag/fly ash-based pastes are more resistant to phosphoric acid attacks compared to ordinary Portland cement-based peers. Furthermore, it is also observed that the kinetics of degradation of the pastes are vastly different, depending on their binders: the degradation process of ordinary Portland cement-based pastes can be described by using Power law, while the degradation process of alkali-activated slag/fly ash-based pastes is divided into an early stage and a later stage which can be described by using the Hill function and the Power law, respectively. The theoretical model developed in this study predicts that, under strong phosphoric acid condition for a period of 50 years, alkali-activated slag/fly ash-based pastes could potentially reduce the degradation depth by around 70%–80% in comparison to ordinary Portland cement-based pastes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Osteoclasts are the exclusive cells of bone resorption. Abnormally activating osteoclasts can lead to low bone mineral density, which will cause osteopenia, osteoporosis, and other bone disorders. To ...date, the mechanism of how osteoclast precursors differentiate into mature osteoclasts remains elusive. MicroRNAs (miRNAs) are novel regulatory factors that play an important role in numerous cellular processes, including cell differentiation and apoptosis, by post-transcriptional regulation of genes. Recently, a number of studies have revealed that miRNAs participate in bone homeostasis, including osteoclastic bone resorption, which sheds light on the mechanisms underlying osteoclast differentiation. In this review, we highlight the miRNAs involved in regulating osteoclast differentiation and bone resorption, and their roles in osteoporosis.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
•An ordinary Portland cement repairing mortar enhanced by aqueous epoxy resin was prepared.•Flexural strength and flexural toughness were increased irrespective of epoxy resin dosages.•An optimal ...dosage of epoxy resin exists for improving different interface bonding strengths.•Both compressive strength and flexural toughness influence interface bonding performance.
An aqueous epoxy resin with four different dosages was employed to enhance ordinary Portland cement (OPC) mortar for the first time used as a polymer-cement repairing material. Experimental results showed that the flexural toughness of the epoxy resin modified OPC mortar was obviously improved without losing too much compressive strength. In addition, three different interface bonding strengths used for evaluation of the interface bonding properties were all enhanced with certain dosages of epoxy resin. For instance, the interfacial flexural bonding strength, direct interface shear strength and interface tensile strength of the OPC mortar with epoxy resin dosage at 5% was increased by approximately 16.7%, 29.8% and 6.9% respectively compared to the control mortar without epoxy resin. It is assumed that the epoxy resin formed as polymer films which could improve the microstructure of OPC mortars as evidenced by scanning electron microscopy analysis via integrating different components in binder matrix and crack bridging effect is the main reason for the related improvements. Thus, this newly developed OPC mortar reinforced by suitable contents of aqueous epoxy resin is a promising repairing material for mitigating deteriorations of concrete which awaits further applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
After fracture, mesenchymal stem cells (MSCs) and growth factors migrate into the fracture callus to exert their biological actions. Previous studies have indicated that dynamic loading induced ...tissue deformation and interstitial fluid flow could produce a biomechanical environment which significantly affects the healing outcomes. However, the fundamental relationship between the various loading regimes and different healing outcomes has not still been fully understood. In this study, we present an integrated computational model to investigate the effect of dynamic loading on early stage of bone fracture healing. The model takes into account cell and growth factor transport under dynamic loading, and mechanical stimuli mediated MSC differentiation and tissue production. The developed model was firstly validated by the available experimental data, and then implemented to identify the loading regimes that produce the optimal healing outcomes. Our results demonstrated that dynamic loading enhances MSC and growth factor transport in a spatially dependent manner. For example, compared to free diffusion, dynamic loading could significantly increase MSCs concentration in endosteal zone; and chondrogenic growth factors in both cortical and periosteal zones in callus. Furthermore, there could be an optimal dynamic loading regime (e.g. 10% strain at 1 Hz) which could potentially significant enhance endochondral ossification.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•The constraint conditions of the spatial position and orientation (SPO) of the bone needle are established in numerical analysis, and the machine learning algorithm is combined to obtain the SPO ...vector of the bone needles.•A batching modeling method for damaged pelvic and needles inserted with different SPO is used to create a total of 150 finite element models.•The multiple index evaluation model of the spatial pose of the bone needle is established.
For robot-assisted pelvic fracture reduction, at least two bone needles need to be inserted into the ilium of the affected pelvis, and the robot clamping device is connected with the bone needles. The biomechanical properties of the pelvic musculoskeletal tissues are different with the different Spatial Position and Orientation (SPO) of the bone needles. In order to determine the optimal SPO of bone needle pairs, the constraints between the bone needles and the pelvis are analyzed, and the SPO vectors of 150 groups bone needles are obtained by the KNN-hierarchical clustering method; a batch modeling method of bone needles with different SPO is proposed. 150 finite element models of damaged pelvic musculoskeletal tissue with different SPO of bone needles are established and simulated. The stress and strain distribution homogenization of musculoskeletal tissue with bone needles as evaluation index, the simulation results of 150 models are evaluated. Results show that, the anterior superior iliac spine and the anterior inferior iliac spine are suitable regions to place bone needles in the pelvis, and the optimal distribution of the needle combination is found in this region. The overall stress and strain distribution of the damaged pelvic musculoskeletal tissue under the large reduction force is the best.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A two-stage framework to estimate the overall system reliability and failure modes.•Find out the priority of the routes in the system and the most likely failure mode.•Estimate system reliability ...using first order reliability method and Ditlevsen bounds.
The condition of road networks which connect disaster affected areas and final disposal sites has a critical role in the management of disaster waste. In this paper, we present a two-stage framework to estimate the overall reliability and failure modes of a disaster waste management system considering the reliability of each route involved in the road network. In the first stage, first order reliability method and Ditlevsen bounds are applied to estimate system reliability. In the second stage, an event tree approach is implemented to analyse the failure modes of the system. The methodology is demonstrated with an artificial case study considering three different scales of disasters. The results obtained from the case study can provide information to decision makers regarding the priority of the routes in the system and the most likely failure mode.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Maintaining post-operative mechanical stability is crucial for successfully healing intertrochanteric fractures treated with the Proximal Femoral Nail Antirotation (PFNA) system. This stability is ...primarily dependent on the bone mineral density (BMD) and strain on the fracture. Current PFNA failure analyses often overlook the uncertainties related to BMD and body weight (BW). Therefore, this study aimed to develop a probabilistic model using finite element modeling and engineering reliability analysis to assess the post-operative performance of PFNA under various physiological loading conditions. The model predictions were validated through a series of experimental test. The results revealed a negative nonlinear relationship between the BMD and compressive strain. Conversely, the BW was positively and linearly correlated with the compressive strain. Importantly, the compressive strain was more sensitive to BW than to BMD when the BMD exceeded 0.6 g/cm3. Potential trabecular bone compression failure is also indicated if BMD is equal to or below 0.15 g/cm3 and BW increases to approximately 2.5 times the normal or higher. This study emphasizes that variations in the BMD significantly affect the probability of failure of a PFNA system. Thus, careful planning of post-operative physical therapy is essential. For patients aged > 50 years restrictions on high-intensity activities are advised, while limiting strenuous movements is recommended for those aged > 65 years.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Although similarity simulation experiments have been widely used in geotechnical engineering, their application in soft rock mechanics is still limited due to the complex water–rock interaction of ...such rocks. The purpose of this study was to synthesise red mudstone–like materials by the method of mineral composition and proportion are completely similar to that of natural rock samples, using sodium silicate content, compression time and vertical stress to investigate the mechanical properties and composition of soft rocks. The physical and mechanical properties of the synthetic red mudstone–like materials were compared with those of natural red mudstone by the density, acoustic characteristics, and microstructure investigation as well as uniaxial and triaxial compression tests. The results show that the synthetic red mudstone–like materials can reproduce the physical and mechanical properties of natural red mudstone. They show that sodium silicate content is one of the most important factors governing mechanical properties, such as internal friction angle, of the synthetic red mudstone–like materials. Importantly, the synthesis method developed in this study could potentially be widely implemented in rock mechanics and engineering.
•Combination of cementation and compaction is considered in the synthesis method.•Red mudstone soft rock which is sensitive to mechanics and water is synthesised.•Red mudstone–like materials are similar to natural rock in minerals and properties.•The synthetic method can be used to obtain soft rocks with certain properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The corrosion of offshore reinforced concrete structures under combined chloride and sulfate ions attack is a complex corrosion phenomenon. The purpose of this study is to develop numerical models in ...conjunction with experimental studies for long-term durability assessment of offshore concrete structures. A numerical model was developed to describe the simultaneously transport of chloride and sulfate ions considering the competitive binding by hardened cement pastes effect. The model was validated by a series of experimental studies. The validated model was implemented to predict the service life of the offshore RC structures under various chloride and sulfate solutions. The results show that chloride ions induced corrosion of steel bars in offshore RC structures is highly influenced by the concentration of sulfate ions. The sulfate ions induced concrete expansion and cracking from ettringite formation could potentially accelerate chloride ions induced corrosion of steel bars in concrete, ultimately the premature failure of the offshore RC structures.
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•Reactive transport model of coupled sulfate and chloride ions was proposed.•The theoretical model was calibrated by a series of experimental work successfully.•The filling effect induced by reaction product was described by using reverse Hill Function.•The competitive binding of chloride and sulfate ions on chloride-induced corrosion was confirmed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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