On effects of freezing and thawing cycles of concrete containing nano-[Formula: see text]: experimental study of material properties and crack simulation.

Construction during cold weather can lead to freezing accidents in concrete, causing significant hidden threats to the project's performance and safety by affecting the mechanical properties and durability reduction. This study aims to deduce the compressive strength and durability of the concrete containing nano-[Formula: see text] under freezing-thawing cycles with the Caspian seawater curing condition. The specimens were subjected to freezing-thawing cycles according to ASTM C666. Furthermore, crack propagation in the concrete after freezing-thawing cycles is simulated. The results reveal that adding until nano-[Formula: see text] until 6% improved compressive strength before and after freezing-thaw cycles. The water permeability experiences a substantial reduction as the amount of nano-[Formula: see text] increases. Furthermore, the water permeability exhibits a positive correlation with the number of cycles, resulting in significantly higher values after 150 cycles compared to the initial sample. Moreover, adding 8% nano-[Formula: see text] reduced the depth of water permeability and chloride ion penetration after 150 cycles by 57% and 86%, respectively. The crack simulation results indicate that concrete containing 6% nano-[Formula: see text] shows an optimal resistance against crack formation. Concrete with 6% nano-[Formula: see text] requires 13.88% less force for crack initialization after 150 freezing and thawing cycles. Among different nano-[Formula: see text] percentages, 6% shows the best crack resistance and 8% the minimum water permeability and chloride ion penetration.

Magnetic Resonance Imaging-based biomechanical simulation of cartilage: A systematic review.

MRI-based mathematical and computational modeling studies can contribute to a better understanding of the mechanisms governing cartilage's mechanical performance and cartilage disease. In addition, distinct modeling of cartilage is needed to optimize artificial cartilage production. These studies have opened up the prospect of further deepening our understanding of cartilage function. Furthermore, these studies reveal the initiation of an engineering-level approach to how cartilage disease affects material properties and cartilage function. Aimed at researchers in the field of MRI-based cartilage simulation, research articles pertinent to MRI-based cartilage modeling were identified, reviewed, and summarized systematically. Various MRI applications for cartilage modeling are highlighted, and the limitations of different constitutive models used are addressed. In addition, the clinical application of simulations and studied diseases are discussed. The paper's quality, based on the developed questionnaire, was assessed, and out of 79 reviewed papers, 34 papers were determined as high-quality. Due to the lack of the best constitutive models for various clinical conditions, researchers may consider the effect of constitutive material models on the cartilage disease simulation. In the future, research groups may incorporate various aspects of machine learning into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification, such as gait analysis.

Contaminant transport in soil: A comparison of the Theory of Porous Media approach with the microfluidic visualisation.

Visualisation of the groundwater flow and contaminant transport can play a significant role for a better understanding of contaminant fate, which helps decision-makers and contaminated site planners to choose and implement the best remediation strategies. In this paper, a microfluidic chip coated with nanoclay was developed to mimic soil behaviour. Scanning electron microscopy (SEM) images and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed that all the features and surfaces are coated with nanoclay. The change of contact angle for the native polydimethylsiloxane (PDMS) from 151°â€¯±â€¯4° to 73°â€¯±â€¯6° for modified ones is indicative of a considerable shift to hydrophilic behaviour. Moreover, the transport process in the developed chip was simulated utilising the Theory of Porous Media (TPM) and computational fluid dynamic (CFD) approaches. Although the results of both numerical approaches are in good agreement with experiments, the Root Mean Square Error (RMSE) of the predicted contaminant concentration by TPM at two observation points is less than that of CFD.

Optimal remediation design and simulation of groundwater flow coupled to contaminant transport using genetic algorithm and radial point collocation method (RPCM).

The simulation-optimisation models of groundwater and contaminant transport can be a powerful tool in the management of groundwater resources and remediation design. In this study, using Multiquadratic Radial Basis Function (MRBF) a coupled groundwater flow and reactive transport of contaminant and oxidant was developed in the framework of the Meshfree method. The parameter analysis has determined the optimum shape parameter (0.97), and the results of the model were compared with a physical sandbox model which were in good agreement. The genetic algorithm approach was used to find the optimum design of the remediation using permanganate as an oxidant. To find the optimum design we considered two objectives and two constraints. The results revealed that the breakthrough of contaminant to the downstream area of interest and the concentration of the contaminant in this area is reduced significantly with optimisation.

Impact of Simulated Microgravity on Cytoskeleton and Viscoelastic Properties of Endothelial Cell.

This study focused on the effects of simulated microgravity (s-µg) on mechanical properties, major cytoskeleton biopolymers, and morphology of endothelial cells (ECs). The structural and functional integrity of ECs are vital to regulate vascular homeostasis and prevent atherosclerosis. Furthermore, these highly gravity sensitive cells play a key role in pathogenesis of many diseases. In this research, impacts of s-µg on mechanical behavior of human umbilical vein endothelial cells were investigated by utilizing a three-dimensional random positioning machine (3D-RPM). Results revealed a considerable drop in cell stiffness and viscosity after 24 hrs of being subjected to weightlessness. Cortical rigidity experienced relatively immediate and significant decline comparing to the stiffness of whole cell body. The cells became rounded in morphology while western blot analysis showed reduction of the main cytoskeletal components. Moreover, fluorescence staining confirmed disorganization of both actin filaments and microtubules (MTs). The results were compared statistically among test and control groups and it was concluded that s-µg led to a significant alteration in mechanical behavior of ECs due to remodeling of cell cytoskeleton.

Effects of an antimitotic drug on mechanical behaviours of the cytoskeleton in distinct grades of colon cancer cells.

Biomechanical behaviours of cells change during cancer progression due to alterations in the main cytoskeletal proteins. Microtubules play a vital role in mitosis and in supporting the integrity of the cell due to their ability to withstand high compressive loads. Accordingly, microtubule-targeting agents (MTAs) have become one of the most promising classes of drugs in cancer therapy. This study evaluated changes in visco-elastic parameters induced by an appropriate concentration of an antimitotic drug in two different grades of colon cancer cells. Actin microfilaments and microtubules contents in the cells were evaluated by Western blot analysis and fluorescence intensity calculation. Micropipette aspiration experiments showed that the MTA had distinct mechanical effects on different cell lines. The more aggressive the cells, the greater the reduction in elasticity and viscosity. Invasive cells had a higher initial instantaneous Young's modulus than primary cells, but this reduced to approximately one half of the values for primary cells after 48 h of drug treatment. A considerable association was seen between the changes in mechanical properties and the microtubule to F-actin microfilament content ratio, which decreased with MTA treatment.

Mechanical properties of cancer cytoskeleton depend on actin filaments to microtubules content: investigating different grades of colon cancer cell lines.

Biomechanical properties of cancer cells have been proposed as promising biomarkers to investigate cancer progression. Cytoskeletal reorganization alters these characteristics in different grades of cancer cells. In the present study based on the micropipette aspiration method, whole body evaluation for two different colon cancer cells was performed to determine viscoelastic parameters of the cells. A finite element model was developed for verification of experiments and predicting some behaviors of cells. Western blot analysis and fluorescence intensity for actin microfilaments and microtubules were performed to measure cell content of the proteins. It was illustrated that the proportion of microtubules and actin microfilaments is different in grade I and grade IV colon cancer cells in a manner that microtubules attain an effectual role in progressive reorganization of cytoskeleton in transition from nonaggressive to malignant phenotypes in cancer cells. Furthermore, it was concluded that larger instantaneous Young's modulus value for high grade cells is related to the existence of extensively build-up actin networks at the cell cortex. Based on the cell mechanics results, a simple parameter is suggested for sorting different grades of colon cancer cells.