Length Of Zone Research Articles

A theoretical model for the prediction of fracture process zone in concrete under fatigue loading: Energy based approach

Characterizing the fracture behaviour of concrete and accurately predicting its service life under fatigue loading poses a significant challenge due to its heterogeneous nature and complex fracture mechanisms. The proposed study focuses on developing an energy based theoretical formulation for predicting the evolution of the fracture process zone throughout repetitive loading cycles. A stiffness degradation approach has been adopted for developing the formulations for the critical energy dissipation and fully developed fracture process zone. Subsequently, the proposed analytical expressions have been calibrated and validated by performing experiments under centre point bending and using available experimental results in the literature. Experiments have been conducted on a centre-point bend beam with varying aggregate size in conjunction with the digital image correlation (DIC) technique to estimate the fracture characteristics. The influence of specimen size and heterogeneity has been discussed in the context of predicting the fracture behaviour, critical dissipated energy, and process zone length of plain concrete beam specimens under fatigue loading. The results indicate that the process zone length and critical energy release rate increase with an increase in specimen size, while the same decreases with an increase in aggregate size.

Experimental study on crack propagation pattern and fracture process zone evolution based on far-field displacement by using DIC

This study utilizes digital image correlation (DIC) technology to measure the far-field displacements and strains of rock specimens during the entire loading and unloading. Through analyzing the distributions of strain, displacement and their variations per unit length at different stages, the variations of both length and migration velocity of the fracture process zone (FPZ) were studied, and the crack propagation was also investigated. In addition, the entire path of crack propagation was observed by scanning electron microscope (SEM). The results reveal that (1) the fractured ligament can be divided into three zones based on the displacement variation per unit length: intact zone, crack propagation zone, and FPZ. (2) The FPZ length reaches its maximum at the peak load and then decreases, and the minimum length even is only 1/3–1/2 of the maximum length. The FPZ migration velocity is − 48 to 1460 m/s. FPZ’s microscale features are intergranular microcracks, transgranular microcracks, cleavage, and debris on fracture surface and around main crack propagation path. (3) The crack propagation length during peak load to peak-post 90% accounts for more than 1/3–1/4 of the entire post-peak length. Crack propagation is alternating fast and slow, i.e., the velocity of crack propagation varies regularly in the range of 24–700 m/s. The region of crack initial propagation is more severely damaged compared to other propagation regions.

Removal of protein wastes by amidoximated polyacrylonitrile nanofiber membrane decorated with dye wastes in batch and flow modes

Amidoximated polyacrylonitrile nanofiber membranes (P-Oxime) were functionalized with a reactive green 19 (RG19, as a model dye waste), to remove lysozyme as a soluble microbial protein model. The P-Oxime-RG19 nanofiber membranes were applied to remove lysozyme in batch and flow modes. The most effective removal capacity of P-Oxime-RG19 nanofiber membranes for lysozyme in batch mode was 1126.37 mg/g. The performance of P-Oxime-RG19 nanofiber membranes for removal of lysozyme in flow mode was further investigated under different pH values, loading flow rates, and loading concentrations of lysozyme. The influences of process parameters on the shape of the breakthrough curve were analyzed, and the experimental results were fitted with various dynamic models to understand the removal behavior of P-Oxime-RG19 nanofiber membranes. The results illuminated the substantial variations in the dynamic binding characteristics of P-Oxime-RG19 nanofiber membranes, including breakthrough time, dynamic binding capacity, mass transfer zone length, and membrane bed utilization. The adsorbed lysozyme could be completely washed out from the dyed membrane using 1.5 M NaCl.

Influence of specimen geometry on the energy release rate in concrete

The energy release rate during the crack propagation in concrete was studied using three-point bending (TPB) beams with different geometries. Expressions for determining the energy release rate were established. A total of 44 beams, i.e., TPB specimens with the height of 150 mm and various spans and the same span of 800 m but different heights, named as Series-T and Series-TH, respectively, were tested. The obtained results reveal that (1) with the crack propagation, the energy release rate curves (GR-curves) monotonically increased and convergence to the fracture energy of each specimen, and the average values were 161.136 N/m and 112.343 N/m for Series-T and Series-TH. (2) For Series-T, with increasing the specimen span from 300 mm to 900 mm, the maximum fracture process zone (FPZ) length kept constant of 68.317 mm, and for Series-TH, the result increased by 187.6 % with increasing the specimen height from 100 mm to 300 mm. Moreover, the relative FPZ length was not affected by the spans and depths of the specimens. (3) The evolution of crack tip opening displacement was only affected by the specimen ligament length, i.e. for the same crack extension length, a larger value was noticed for longer ligament length. (4) The stability during crack propagation can be analyzed using GR-curves.

Forming characteristics of thin-walled tubes manufactured by free bending process-based nontangential rotation bending die

The free-bending process of a metal tube involves a geometric relationship between the eccentricity, the rotation angle of the bending die, the deformation zone length, and the bending radius. Ideally, during the forming process, the contact position between the bending die, and the outer bend of the tube remains tangent. However, due to factors such as the clearance of the bending die and material properties, the rotation angle can be adjusted within a specific range while still ensuring smooth tube formation. The tangential state is disrupted when the rotation angle changes, resulting in overbending or underbending. Thus, in this study, a new theoretical analysis of the free bending process, accounting for clearance, was developed to analyze the material flow and changes in the bending radius during the nontangential contact between the bending die and the tube. In addition, the reasons for achieving smooth tube bending even after adjusting the rotation angle were explained, and the deformation mechanism of the tube under the combined effects of additional tangential force from the bending die and axial propulsive force was analysed. Furthermore, the impact of the rotation angle on the bending radius and the displacement of the strain neutral layer (strain NL) was determined. Afterwards, finite element (FE) modeling and forming experiments were conducted to verify the proposed theoretical analysis under different deformation zone lengths and eccentricities conditions. Besides, the distribution of the inner and outer wall thicknesses of the tube under the nontangential rotation of the bending die was further analysed. The simulation and experimental results fit well with that obtained from theoretical analysis.

Foveal Thickness Fluctuations in Anti-VEGF Treatment for Central Retinal Vein Occlusion

The aim of this study was to examine the effects of foveal thickness (FT) fluctuation (FTF) on 2-year visual and morphological outcomes of eyes with central retinal vein occlusion (CRVO) undergoing anti-VEGF treatment for recurrent macular edema (ME) based on a pro re nata regimen. Retrospective, observational case series. We analyzed 141 treatment-naive patients (141 eyes) with CRVO-ME at a multicenter retinal practice. We assessed FT using OCT at each study visit. Patients were divided into groups 0, 1, 2, and 3 according to increasing FTF. We evaluated the logarithm of the minimal angle of resolution (logMAR) best-corrected visual acuity (BCVA), the length of the foveal ellipsoid zone (EZ) band defect measured using OCT, and the association of FTF with VA and EZ band defect length. The mean baseline logMAR BCVA and FT were 0.65±0.52 (Snellen equivalent range: 20/20-20/2000) and 661.1±257.4 μm, respectively. The mean number of anti-VEGF injections administered was 5.6±3.6. At the final examination, the mean logMAR BCVA and FT values were significantly improved relative to the baseline values (both P<0.01). During the observation, BCVA longitudinally improved in Groups 0 and 1, remained unchanged in Group 2, and worsened in Group 3. Likewise, the length of the foveal EZ band defect did not increase in Group 0; however, it gradually increased in Groups 1, 2, and 3. Foveal thickness fluctuation was significantly and positively associated with the logMAR BCVA and length of the foveal EZ band defect at the final examination (P<0.01). The final logMAR BCVA of patients developing neovascular complications was 1.27±0.72 (Snellen equivalent range: 20/50-counting fingers), which was significantly poorer than that of patients without complications (P<0.001). There was no significant difference in the neovascular complication rate among the FTF groups (P=0.106, Fisher exact test). In eyes receiving anti-VEGF treatment for CRVO-ME, FTF can longitudinally impair the visual acuity and foveal photoreceptor status during the observation period, thus influencing the final outcomes. However, neovascular complications, which would also lead to a poor visual prognosis, may not be associated with FTF. The authors have no proprietary or commercial interest in any materials discussed in this article.

Numerical Modeling of the Dispersion Characteristics of Pollutants in the Confluence Area of an Asymmetrical River

It is challenging to investigate the transport and dispersion of contaminants in river confluence areas due to the complex flow dynamics. In recent studies on the flow dynamics in river confluence areas, it has been revealed that changes in inflow conditions (discharge ratio, width-depth ratio and concentration difference) can greatly influence pollutant diffusion. In this study, an asymmetric confluence-type river is modeled by a three-dimensional hydrodynamic water quality model, and three hydrodynamic scenarios are numerically simulated. The results show that a higher discharge ratio and width-depth ratio led to an increase in the lateral diffusion area of pollutants, deviation in the trajectory line of the mixing interface towards the opposite bank of the interchange, and an increase in the mixing rate of pollutants. For R = 0.267 and b/h = 3.75, the pollutants at the bottom are completely mixed in the exit end section. However, the difference in the pollutant concentration slightly affects the area, length and shape of the pollutant dispersion zone and notably affects only the concentration in each section.

Possibilities and limits of modeling cavitation in high-pressure homogenizers – a validation study

High-pressure homogenizers are widely used in industrial processes to produce emulsions with small droplet sizes. During the process, cavitation occurs under industrial process conditions. In order to investigate the flow conditions inside a homogenizer geometry, CFD simulations are commonly used, since it is not possible to evaluate local flow conditions experimentally. However, these studies have, so far, investigated flow under non-cavitating conditions, which do not adequately reflect industrial process conditions. This study investigates the extent to which the two cavitation models, the Schnerr-Sauer model and the Zwart-Gerber-Belamri model, can represent cavitation in the gap of the homogenizing geometry using RANS simulation. Simulations are validated with experimental cavitation visualization data. Results show that the Schnerr-Sauer model (with appropriately set modeling constants) is able to accurately predict the operating conditions responsible for cavitation inception in the valve, as well as the length and width of the cavitation zone.

Simulations of Compression Ramp Shock Wave/Turbulent Boundary Layer Interaction Controlled via Steady Jets at High Reynolds Number

Shock wave/turbulent boundary layer interaction (SBLI) is one of the most common physical phenomena in transonic wing and supersonic aircraft. In this study, the compression ramp SBLI (CR-SBLI) was simulated at a 24° corner at Mach 2.84 using the open-source OpenFOAM improved delayed detached eddy simulation (IDDES) turbulence model and the “Rescaling and Recycling” method at high Reynolds number 1.57×106. The results of the control effect of the jet vortex generator on CR-SBLI showed that the jet array can effectively reduce the length of the separation zone. The simulation results of different jet parameters are obtained. With the increasing jet angle, the reduction in the length of the separation zone first increased and then decreased. In this work, when the jet angle was 60°, the location of the separation point was x/δ=−1.48, which was smaller than other jet angles. The different distances of the jet array also had a great influence. When the distance between the jet and the corner djet=70 mm, the location of the separation point x/δ=−1.48 was smaller than that when djet=65/60 mm. A closer distance between the jet hole and the corner caused the vortex structures to squeeze each other, preventing the formation of a complete vortex structure. On the other hand, when the jet was farther away, the vortex structures could separate effectively before reaching the shock wave, resulting in a better inhibition of SBLI. The simulation primarily focused on exploring the effects of the jet angle and distance, and we obtained the jet parameters that provided the best control effect, effectively reducing the length of the CR-SBLI separation zone.

Experimental analysis of pulsatile flow effects on flow structure in transitional-type cavity

Studies combining flow separation and pulsatile flow phenomena are inherent in the field of biomedicine and have many engineering and biomedical applications. In this study, the pulsatile flow structure is investigated experimentally based on a transitional-type cavity with a length-to-depth ratio of 8 using a microparticle image velocimetry system. A pulsatile flow is generated by pulsating the inlet pressure in sinusoidal pulses using a pressure control unit. Stationary flow and four sets of pulsatile parameters are investigated: two pulsation amplitudes (A = 0.15 and 0.60) and two pulsation frequencies (f = 0.5 and 1 Hz) in the Reynolds range of 50–2000. The recirculation flow dynamics in a cavity are analyzed by investigating the effect of pulsations on the flow structure and statistical flow parameters such as vorticity, shear rate, and turbulence intensity. The analysis shows that the effect of the pulsation amplitude on the recirculation zone dynamics is more prominent than that of the pulsation frequency. The magnitude of the recirculation zone reduction achieved by the pulsatile flow is inversely proportional to the pulsation amplitude. A reduction in the recirculation zone length decreases the shear rate distribution along the cavity. Additionally, an analysis into the turbulence intensity shows that effect of pulsations is negligible when the flow approaches the turbulent flow regime.

Effect of different loading rates on the fracture behavior of FRP‐reinforced concrete

AbstractIn order to study the effect of different loading rates on the fracture behavior of fiber‐reinforced polymer (FRP) reinforced concrete, the fracture experiments of FRP‐reinforced concrete beams under different loading rates were carried out. The calculation method of fracture toughness was given by analytic deduction, and the effects of different loading rates on the fracture parameters were analyzed. The experimental results show that there are three critical points in the fracture process of FRP‐reinforced concrete beam, which are the crack initiation load, crack resistance load, and ultimate load points. The effective crack length at the crack resistance load point increases with the increase of loading rate, and the effective crack length at the ultimate load point does not vary as the loading rate. With the increase of loading rate, the elastic modulus and fracture toughness increase gradually, and there is a logarithmic relationship with the loading rate, which has obvious rate correlation. The fracture process zone (FPZ) length of FRP‐reinforced concrete beams gradually decreases with the increase of loading rate.

Fracture process zone in crystalline rock: effect of specimen size and shape

Ability to predict fracture properties of granular materials based on their size and loading conditions needs rigorous experimental evidence. Charcoal granite specimens of various sizes and geometries are tested under three- and four-point bending to investigate the effect on the fracture toughness of rock and size of the fracture process zone calculated using Digital Image Correlation (DIC), with validation provided by Acoustic Emission (AE). Two different methods to evaluate the length of the fracture process zone using DIC are adopted: the first one assumes that a traction free crack does not propagate in the pre-peak regime, while the second one hypothesizes that a cohesionless crack may exist at peak load before unstable crack growth. The effects of specimen size, geometry, and loading conditions are found to be more prominent for the specimen sizes used in the laboratory but are predicted to become less significant and eventually negligible as the specimen size increases. DIC results are in general agreement with localization of AE events, but the former technique is suggested due to greater resolution and ability of continuous measurements of the fracture process zone dimensions.

Fracture behavior of high-temperature granite subjected to liquid nitrogen cooling: Semi-circular bending test and crack evolution analysis

Liquid nitrogen fracturing is an effective technique for stimulating reservoirs in hot dry rock exploitation. The application of low-temperature liquid nitrogen to high-temperature granite generates thermal stress, thereby altering its mechanical properties and fracture behavior. This study focused on type I fracture characteristics by conducting semi-circular bending tests on high-temperature granite treated with liquid nitrogen. The fracture behavior was analyzed using acoustic emission (AE) and digital image correlation methods. The fractured surface morphology was examined using laser scanning, and fractal theory and tortuosity analysis were employed to assess the fracture surface roughness. Scanning electron microscopy (SEM) provided insight into the impact of liquid nitrogen cooling on fracture characteristics. The findings indicated that treated granite specimens below 150℃ exhibited an increased peak load, fracture toughness, and fracture energy compared to untreated specimens. SEM images revealed isolated microcracks in specimens at 25℃ and 150℃, which effectively passivated pre-existing notches and increased fracture toughness. For granites above 200℃ following liquid nitrogen treatment, P-wave velocity, peak load, fracture toughness, and fracture energy decreased significantly as temperature increased. AE signals were observed earlier for granites at higher temperatures. The length of the fracture process zone increased with temperature, and the crack tip opening displacement exhibited a step-like increase at 600℃ under loading. The fractal dimension of the fracture surface varied with temperature, whereas the tortuosity exhibited a substantial increase with increasing temperature. As the temperature difference increased, an increasing number of microcracks appeared, forming interconnected networks that compromised the rock integrity, ultimately leading to reduced fracture toughness and the development of a rougher failure surface.

Improvement of actin dynamics and cognitive impairment in diabetes through troxerutin-mediated downregulation of TRPM7/CaN/cofilin

Diabetic cognitive impairment is a central nervous complication of diabetes mellitus. Its specific pathogenesis is unknown, and no effective treatment strategy is currently available. An imbalance in actin dynamics is an important mechanism underlying cognitive impairment. Transient receptor potential channel 7 (TRPM7) mediates actin dynamics imbalance through calcineurin (CaN) and cofilin cascades involved in various neurodegenerative diseases. We previously demonstrated that TRPM7 expression is increased in diabetic cognitive impairment, and troxerutin has been shown to ameliorate diabetic cognitive impairment. However, the relationship between troxerutin and TRPM7 remains unclear. In this study, we hypothesize that troxerutin may improve diabetic cognitive impairment by enhancing actin dynamics through downregulation of the TRPM7/CaN/cofilin pathway. To test this hypothesis, we divided db/m and db/db mice into the following groups: normal control group (NC), normal + troxerutin group (NT), diabetic group (DM), diabetic + troxerutin group (DT) and diabetic + troxerutin + bradykinin group (DTB). The results showed that diabetic mice exhibited cognitive impairment at 17 weeks of age, TRPM7, CaN, cofilin and G-actin were highly expressed in the CA1 region of hippocampus, while p-cofilin and F-actin expression decreased. Furthermore, hippocampal neuronal cellsshowed varying degrees of damage. The length of synaptic active zone, the width of synaptic cleft, and the number of synapses per high-power field were decreased. Troxerutin intervention alleviated these manifestations in the DT group; however, the effect of troxerutin was weakened in the DTB group. In conclusion, our findings suggest that diabetes leads to cognitive impairment, activation of the TRPM7/CaN/cofilin pathway, actin dynamics imbalance, and destruction of hippocampal neuronal cells and synapses. Troxerutin can downregulate TRPM7/CaN/cofilin, improve actin dynamics imbalance, and ameliorate cognitive impairment in diabetic mice. This study provides a new avenue for exploring and treating cognitive impairment in diabetes.

A Novel Analytical Solution for Ponded Infiltration With Consideration of a Developing Saturated Zone

AbstractPonding at the soil surface exerts profound impacts on infiltration. However, the effects of ponding depth on infiltration, especially the development of a saturated zone below the soil surface, have yet to be considered in present infiltration models. A new general Green‐Ampt model solution (GAMS) was derived for a one‐dimensional vertical infiltration problem under a uniform initial moisture distribution with ponding on its surface. An expression was included in the new solution for simulating the saturated layer developed below the soil surface as long as the pressure head at the surface is sufficiently high to saturate the soil. The GAMS simulates the infiltration processes closer to the numerical solution by HYDRUS‐1D than the traditional and the recently improved Green‐Ampt model. Moreover, an inversion method to improve the estimates of soil hydraulic parameters from one‐dimensional vertical infiltration experiments that is based on the GAMS was suggested. The effect of ponding depth (hp), initial soil moisture content, soil texture, and hydraulic soil properties (saturated hydraulic conductivity Ks, water‐entry suction hd and shape coefficient n of soil water retention curve) in the saturated zone was also evaluated. The results indicate that the saturated zone length increased at a comparable rate with the unsaturated wetted zone length during infiltration. Generally, a larger saturated zone was found for soils with higher initial soil moisture contents, coarser texture, higher Ks values, greater n, and lower −hd. Our findings reveal that including the saturated zone in the infiltration model yields a better estimate of the soil hydraulic parameters. The proposed GAMS model can improve irrigation design and rainfall‐runoff simulations.

Influence of specimen size on granite fracture characteristics and acoustic emission phenomena under mode I loading conditions

The rock mode I fracture characteristics and the size effect are of great significance in understanding the crack initiation, nucleation, propagation, and characterizing the fracture toughness of rocks which is essential for predicting the behavior of rock masses and designing underground structures. In this paper, three-point bending fracture experiments were carried out using single-edge notched beam specimens of different sizes. The fracture characteristics of the entire loading stage, including the post peak stage, were analyzed using digital image correlation (DIC) technology and acoustic emission (AE) technology. Specifically, the calculation of the b value uses the Fisher optimal split and global search algorithm (FGS) method. The results show that both the Fracture process zone (FPZ) length and fracture toughness of granite are size-dependent parameters, and the FPZ length growth rate increases with increasing load level. The failure mode of the source during fracture is mainly tensile failure, and the proportion of tensile failure tends to increase with the increase of specimen size. The temporal b value, average AF value and RA value show corresponding stage changes with time, and the minimum b value, minimum AF value and maximum RA value can characterize the maximum of macroscopic growth rate.

Experimental study on the effect of initial accumulation pattern on gas explosion and explosion suppression in a real roadway

In real roadways, gas is prone to accumulate, which in turn can lead to explosive hazards. The state of gas accumulation has a significant impact on the degree of disaster caused by gas explosive hazards. In this study, gas explosion propagation in complex situations was investigated in the actual roadway. The mechanism of explosion suppression was explored from the perspective of kinetic analysis of chemical reactions. It is found that the peaks of explosion pressure occur in the gas accumulation zone. The length of explosion flame is 3–5 times larger than that of the initial gas accumulation zone. As the initial accumulation volume increases, the flame propagation velocity (FPV), maximum explosion pressure (MEP) and flame zone length all increase. ABC Powder can effectively suppress explosion flames of gas with different gas accumulation patterns. A prediction model of gas explosion wave energy in the roadway is proposed. The explosion wave energy increases with increasing overpressure ratio. The explosion wave energy decays significantly after 80 m because of explosion suppression. The explosion suppression of ABC powder is a synergistic effect of surface cooling, dilution, physical isolation and chemical mechanisms. The free radical ions generated by the pyrolysis of ABC powder destroy the structure of the flame and make the reaction more difficult, which corresponds to an increase in the critical flame temperature and makes the gas phase dilution effect easier to achieve.

Lack of improvement in anorectal manometry parameters after implementation of a pelvic floor/anal sphincter biofeedback in persons with motor-incomplete spinal cord injury.

Effect of biofeedback on improving anorectal manometric parameters in incomplete spinal cord injury is unknown. A short-term biofeedback program investigated any effect on anorectal manometric parameters without correlation to bowel symptoms. This prospective uncontrolled interventional study comprised three study subject groups, Group 1: sensory/motor-complete American Spinal Injury Association Impairment Scale (AIS) A SCI (n = 13); Group 2 (biofeedback group): sensory incomplete AIS B SCI (n = 17) (n = 3), and motor-incomplete AIS C SCI (n = 8), and AIS D SCI (n = 6); and Group 3: able-bodied (AB) controls (n = 12). High-resolution anorectal manometry (HR-ARM) was applied to establish baseline characteristics in all subjects for anorectal pressure, volume, length of pressure zones, and duration of sphincter squeeze pressure. SCI participants with motor-incomplete SCI were enrolled in pelvic floor/anal sphincter bowel biofeedback training (2 × 6-week training periods comprised of two training sessions per week for 30-45 min per session). HR-ARM was also performed after each of the 6-week periods of biofeedback training. Compared to motor-complete or motor-incomplete SCI participants, AB subjects had higher mean intra-rectal pressure, maximal sphincteric pressure, residual anal pressure, recto-anal pressure gradient, and duration of squeeze (p < 0.05 for each of the endpoints). No significant difference was evident at baseline between the motor-complete and motor-incomplete SCI groups. In motor-incomplete SCI subjects, the pelvic floor/anal sphincter biofeedback protocol failed to improve HR-ARM parameters. Biofeedback training program did not improve anal manometric parameters in subjects with motor-incomplete or sensory-incomplete SCI. Biofeedback did not change physiology, and its effects on symptoms are unknown. Utility of biofeedback is limited in patients with incomplete spinal cord injury in terms of improving HR-ARM parameters.

Activation of p38 MAPK hinders the reactivation of visual cortical plasticity in adult amblyopic mice

ObjectiveTo investigate the impact of p38 mitogen-activated protein kinase (MAPK) signaling on reactivating visual cortical plasticity in adult amblyopic mice. Materials and methodsReverse suture (RS), environment enrichment (EE), and combined with left intracerebroventricular injection of p38 MAPK inhibitor (SB203580, SB) or p38 MAPK agonist (dehydrocorydaline hydrochloride, DHC) were utilized to treat adult amblyopic mice with monocular deprivation (MD). The visual water task, visual cliff test, and Flash visual-evoked potential were used to measure the visual function. Then, Golgi staining and transmission electron microscopy were used to assess the reactivation of structural plasticity in adult amblyopic mice. Western blot and immunohistochemistry detected the expression of ATF2, PSD-95, p38 MAPK, and phospho-p38 MAPK in the left visual cortex. ResultsNo statistically significant difference was observed in the visual function in each pre-intervention group. Compared to pre-intervention, the visual acuity of deprived eyes was improved significantly, the impairment of visual depth perception was alleviated, and the P wave amplitude and C/I ratio were increased in the EE + RS, the EE + RS + SB, and the EE + RS + DMSO groups, but no significant difference was detected in the EE + RS + DHC group. Compared to EE + RS + DHC group, the density of dendritic spines was significantly higher, the synaptic density of the left visual cortex increased significantly, the length of the active synaptic zone increased, and the thickness of post-synaptic density (PSD) thickened in the left visual cortex of EE + RS, EE + RS + SB, and EE + RS + DMSO groups. And that, the protein expression of p-p38 MAPK increased while that of PSD-95 and ATF2 decreased significantly in the left visual cortex of the EE + RS + DHC group mice. ConclusionRS and EE intervention improved the visual function and synaptic plasticity of the visual cortex in adult amblyopic mice. However, activating p38 MAPK hinders the recovery of visual function by upregulating the phosphorylation of p38 MAPK and decreasing the ATF2 protein expression.

Mechanical properties and microstructure of red mud-coal metakaolin geopolymer concrete based on orthogonal tests

Red mud, an industrial solid waste, can be used as a raw material for geopolymer concrete to reduce its environmental damage and achieve resource utilization. Nonetheless, the performance of red mud-based geopolymer concrete is influenced by various factors, and its overall sustainability remains to be comprehensively evaluated, limiting its widespread application. For this reason, this study systematically investigated the effects of water-binder ratio, aggregate-binder ratio, curing conditions, and Na2O/H2O on the water absorption, mechanical properties, and efflorescence degree of geopolymer concrete using Taguchi's orthogonal method. The optimal mixture for maximization of mechanical properties was determined using Design-Expert software. Subsequently, the microscopic properties of the samples were evaluated. In addition, an AHP-CRITIC-TOPSIS model was used to construct a sustainable assessment framework for geopolymer concrete including environmental, social, and economic indicators. The results indicated that the water-binder ratio is the main influencing factor. Excessive water increases the length of interfacial transition zone, coarsens the pore structure, and hinders the condensation process, leading to a degradation of material properties. In terms of sustainability, both M30 and M40 grade geopolymer concretes obtained significantly higher scores than cement concrete, and therefore it is considered a greener alternative.