Segmental Wall Research Articles

Seismic Behavior of Cluster-Connected Prefabricated Shear Walls under Different Axial Compression Ratios

This study analyzes the nonlinear seismic behavior of cluster-connected prefabricated shear walls under varying axial compression ratios. The investigation focuses on the connectivity of shear wall segments assembled using cluster connections rather than separate walls connected by beams. Using the finite element software ABAQUS, this study simulates monotonic horizontal displacement loading to evaluate the yield strength, peak strength, and deformation capacity of the shear walls. The results demonstrate that the horizontal load-bearing capacity of the shear wall significantly improves with an increase in axial compression ratio, while the axial compression ratio also influences ductility. The numerical simulations are validated against experimental data, confirming the accuracy of the model. These findings provide essential insights for optimizing the seismic design of precast shear walls.

Revealing the unrevealed: echocardiography for non-ischemic scar tissue detection.

The detection of myocardial scar tissue profoundly influences athletes care and prognostic categorization. Athletes appear to be at risk of developing fatal arrhythmias when harboring a quiescent cardiac disorder. Early identification of disease in asymptomatic individuals through preparticipation screening is means to prevent these events. We presented a male marathon runner master athlete who came at our Department of Sports Medicine for a preparticipation screening. Baseline 12-lead standard electrocardiogram was normal. A maximal cycle ergometer exercise test revealed exercise-induced premature ventricular contractions (PVCs) with uncommon morphology. Echocardiography revealed an hyperechogenic zone at mid-basal posterior segments of the left ventricle. Twenty-four-hours ECG Holter monitoring, with training session, showed some isolated polymorphic PVCs even during training session. Cardiac magnetic resonance (CMR) confirmed the presence of a non-ischemic left ventricular scar (subepicardial) into the mid-basal segment of the posterior wall. Echocardiography is a first-line, economic, and accessible diagnostic test for athletes and it can be useful, when abnormalities are detected, to indicate further investigations, such as CMR. Although non-ischemic left ventricular scarring is difficult to detect on echocardiography, this event is sometimes possible and require further investigation when observed.

An explicit multilevel power turbulent wall function based on the de-thresholding Douglas–Peucker algorithm

Wall functions are extensively applied in engineering simulations with turbulence. They facilitate a significant increase in the scale of the grids next to the wall, which in turn reduces the total number of grids needed. This optimization enhances computational efficiency, making the simulation process more effective and streamlined. However, the current commonly used wall functions, such as the Spalding wall function, are an implicit expression that needs to be solved iteratively, which affects the computational efficiency, and the multilayer segmented wall function is not smoothly articulated, which affects the fidelity. In this study, based on flat plate direct numerical simulation (DNS) data, combined with structural ensemble dynamics theory, the de-thresholding Douglas–Peucker algorithm is introduced to construct an explicit wall function expression in the form of multilevel power exponential concatenated multiplication. The comparison of the new wall function against DNS data reveals that it demonstrates superior fitting accuracy in contrast to the traditional ones, and eliminates the need for manual calibration, reduces subjective influence, and enhances reliability. The numerical simulation outcomes for the flat plate boundary layer and a series of airfoils showcase the new wall function's exceptional accuracy, which not only meets but also surpasses the demanding standards of engineering practice.

Conventional and 2-Dimensional Speckle Tracking Echocardiography in Fabry Disease

Abstract OBJECTIVE To analyze the myocardial involvement and explore the strain characteristics of the left atrium and the left ventricle in patients with Fabry disease (FD) using conventional echocardiography and 2-dimensional speckle tracking echocardiography (2D-STE). METHODS A retrospective study was conducted. Sixty-nine patients with FD who were treated in the Department of Cardiology, Neurology and Nephrology of Peking University First Hospital from August 2014 to February 2023 and underwent echocardiography examination in the Cardiology Department were collected (FD group). During the same time, 69 age- and sex-matched individuals who had no cardiovascular, cerebrovascular, renal, metabolic, and autoimmune diseases, and had no obvious abnormalities on echocardiography were included in the control group. The clinical data and laboratory tests were collected, and routine echocardiography and 2D-STE were performed to analyze left atrial strain and left ventricular longitudinal strain. The differences in relevant parameters between groups were compared. RESULTS Compared with the control group, the patients in the FD group had smaller body mass index and body surface area, slower heart rate, poorer estimated glomerular filtration rate, and significantly increased brain natriuretic peptide and cardiac troponin I (all P < 0.05). E’med in the FD group was reduced (8.4 ± 3.4 vs. 9.9 ± 2.8, P = 0.006) and E peak, E peak deceleration time, pulmonary artery systolic pressure increased, interventricular septum and left ventricular posterior wall thickened, left ventricular mass index, and early diastolic transmitral inflow velocity/septal mitral annular velocity (E/Eʹ) increased (all P < 0.05). Compared with the control group, left atrial strains [including left atrial strain during reservoir phase (LASr), left atrial strain during contraction phase (LASct), left atrial strain during conduit phase (LAScd)] and left ventricular average global longitudinal strain (GLSavg) were reduced in the FD group. In the segmental longitudinal strain of the left ventricular, the strain was significantly reduced except for the strain of the basal and middle segment of the inferior wall (P < 0.05). CONCLUSIONS Patients with FD usually have multisystem involvement such as kidney and heart. Echocardiography usually shows varying degrees of myocardial hypertrophy and diastolic dysfunction, while left ventricular ejection fraction is normal. Left atrial strain, left ventricular global, and segmental longitudinal strain are all decreased to varying degrees.

Development of A New Model on PC Segmental Retaining Wall Using Solid Bar Anchors and Fin Fish

The development of transportation infrastructure is very important for economic growth. In the context of the construction of precast concrete (PC) segmental retaining walls, the use of innovative technologies such as solid bar anchors and fish fins is the main focus of improving the efficiency and reliability of the structure. This research aims to develop a new model that optimizes the use of solid bar anchors and fin fish in PC segmental retaining walls, with the hope of improving structural performance and extending the service life of the wall. The research methodology includes literature studies, development of mathematical models based on soil mechanics and finite element theory, and numerical simulations using PLAXIS software. The results show that the MSE Wall system with solid bar anchors and fin fish meets the SNI Geotechnical No. 8460 standard of 2017, with safety factors of high bolling, shear, and ground carrying stability. The use of a crossbar necklace configuration with a center to center (ctc) distance of 30 cm provides greater tensile strength than a ctc of 50 cm. This research is expected to make a significant contribution to the development of construction technology that is more efficient, economical, and sustainable.

Reproducibility for carotid wall segmentation using T1-weighted DANTE-SPACE sequence on high-resolution 3-T carotid MRI.

T1-weighted (T1W) magnetic resonance imaging (MRI) using the delay alternating with nutation for excitation-sampling perfection with application-optimized contrasts using different flip angle evolution (DANTE-SPACE) is the preferred imaging technique for evaluation of the vessel wall. To evaluate the intra- and inter-rater reproducibility of carotid wall segmentation on T1W DANTE-SPACE in patients with symptomatic (acute stroke or transient ischemic attack) internal carotid artery (ICA) stenosis. This prospective study included 25 patients with acute (≤3 months) stroke or transient ischemic attack and 50%-99% stenosis of the ICA. All patients underwent 3.0-T high-resolution carotid MRI. Two radiologists independently performed the manual segmentation of the vessel wall and inner lumen of the bilateral carotid artery on DANTE-SPACE. The intraclass correlation coefficient (ICC), Dice similarity coefficient (DSC), and Hausdorff distance (HD) were calculated. The ICCs for intra-rater reproducibility of carotid wall volume, inner lumen volume, and normalized wall index were 0.965, 0.990, and 0.962, respectively. The ICCs for inter-rater reproducibility of carotid wall volume, inner lumen, and normalized wall index were 0.856, 0.981, and 0.904. DSC and HD for intra- and inter-rater reproducibility of carotid wall segmentation were as follows: 0.873 and 0.809 (DSC); and 0.079 and 0.118 (HD), respectively. For evaluation of reproducibility only in the carotid artery with symptomatic stenosis, the ICCs for intra- and inter-rater reproducibility indicated all perfect agreement. T1W DANTE-SPACE is a reproducible sequence for evaluation of the carotid wall using carotid MRI in patients with symptomatic ICA stenosis.

MH2AFormer: An Efficient Multiscale Hierarchical Hybrid Attention With a Transformer for Bladder Wall and Tumor Segmentation.

Achieving accurate bladder wall and tumor segmentation from MRI is critical for diagnosing and treating bladder cancer. However, automated segmentation remains challenging due to factors such as comparable density distributions, intricate tumor morphologies, and unclear boundaries. Considering the attributes of bladder MRI images, we propose an efficient multiscale hierarchical hybrid attention with a transformer (MH2AFormer) for bladder cancer and wall segmentation. Specifically, a multiscale hybrid attention and transformer (MHAT) module in the encoder is designed to adaptively extract and aggregate multiscale hybrid feature representations from the input image. In the decoder stage, we devise a multiscale hybrid attention (MHA) module to generate high-quality segmentation results from multiscale hybrid features. Combining these modules enhances the feature representation and guides the model to focus on tumor and wall regions, which helps to solve bladder image segmentation challenges. Moreover, MHAT utilizes the Fast Fourier Transformer with a large kernel (e.g., 224 × 224) to model global feature relationships while reducing computational complexity in the encoding stage. The model performance was evaluated on two datasets. As a result, the model achieves relatively best results regarding the intersection over union (IoU) and dice similarity coefficient (DSC) on both datasets (Dataset A: IoU = 80.26%, DSC = 88.20%; Dataset B: IoU = 89.74%, DSC = 94.48%). These advantageous outcomes substantiate the practical utility of our approach, highlighting its potential to alleviate the workload of radiologists when applied in clinical settings.

Cyclic behavior and pushover analysis of large scale two-bay, two-story reinforced concrete frames infilled with walls with openings

This study presents experimental results on the seismic behavior of a large-scale two-bay, two-story RC frame with RC infill walls, including openings typical of low-rise RC row buildings in Taiwan. The test findings indicated that the specimen failed due to the failure of the vertical members of the first story. Specifically, the critical wall segments located between openings and between an opening and a boundary column and short columns resulting from the presence of these openings were shown to be the main contributors to the failure. Based on the observed phenomenon during the test, an analytical model was verified and proposed for the tested specimen’s pushover analysis. The selection of plastic hinges in the analytical model was determined according to the Taiwan Earthquake Assessment for Structures by Pushover Analysis (TEASPA). Pushover analysis performed by commercially available software indicated that the analytical model could well capture the specimen's behavior regarding peak base shear, initial stiffness, displacement of each story, and development of plastic hinges.

Interventricular septum involvement is related to right ventricular dysfunction in anterior STEMI patients without right ventricular infarction: a cardiovascular magnetic resonance study.

The value of cardiovascular magnetic resonance (CMR) in assessing and predicting acute right ventricular (RV) dysfunction in patients with anterior ST-segment elevation myocardial infarction (STEMI) remains ascertained. Eightyeight patients with anterior STEMI were prospectively recruited and underwent CMR examinations within one week following the coronary intervention. Patients with RV ejection fraction (RVEF) less than 2 standard deviations below the average at the center (RVEF ≤ 45.0%) were defined as having RV dysfunction. The size of infarction, segmental wall motion, and T1 and T2 mapping values of global myocardium and the interventricular septum (IVS) were measured. Predictive performance was calculated using receiver-operating characteristic curve analysis and logistic regression test. Twentytwo patients presented with RV dysfunction. The RV dysfunction group had a larger IVS infarct extent (54.28 ± 10.35 vs 33.95 ± 15.09%, P < 0.001) and lower left ventricle stroke volume index (33.93 ± 7.96 vs 42.46 ± 8.14ml/m2, P < 0.001) compared to the non-RV dysfunction group. IVS infarct extent at 48.8% best predicted the presence of RV dysfunction with an area under the curve of 0.864. Left ventricular stroke volume index (LVSVI) and IVS infarct extent were selected by stepwise multivariable logistic regression analysis. LowerLVSVI (odds ratio [OR] 0.90; 95% confidence interval [CI], 0.79 to 0.99; P = 0.044) andhigher IVS infarct extent (OR 1.16; 95% CI 1.05 to 1.33; P = 0.01) were found to be independent predictors for RV dysfunction. In patients with anterior STEMI, those with larger IVS infarct extent and worse LV function are more likely to be associated with RV dysfunction.

Research on the new passive optimization strategies for improving the performance of combined solar chimney

Focusing on the Combined Solar Chimney (CSC), this study introduces two innovative passive optimization measures: deflectors and segmented heat-absorbing walls. Using numerical simulations, the impact of five control parameters—the angle and length of the straight deflector, the central angle of the curved deflector, the number of heat-absorbing wall segments, and the Rayleigh number (Ra)—on CSC performance is analyzed. Results indicate that air changes per hour (ACH) can be significantly improved with the implementation of deflectors and segmented walls. Optimal deflector configurations are identified as a 25° angle, a 0.375 length-to-width ratio (l/W), and a 60° central angle. The study recommends using two heat-absorbing wall segments for practical applications. When both measures are applied, ventilation performance can be enhanced by up to 25.71%. Additionally, this research establishes quantitative relationships between the control parameters, ACH, and heat exchange efficiencies, providing a theoretical foundation for practical engineering designs.

A novel approach for the optimum cross-section design of thin-walled box section beams subject to oblique bending based on both adequate-strength and local stability conditions

This study presents a new analytical procedure developed for the optimum cross-section design of the thin-walled box sections subject to oblique bending. The box sections designed in this study have been assumed to be achieved by hollowing out the rectangular solid sections at different subtraction ratios including arbitrary, optimum, and maximum. The optimum subtraction ratio has been determined based on the adequate-strength condition while the maximum subtraction ratio has been determined taking into account both adequate-strength and local buckling conditions. The optimal design of the box sections for the arbitrary subtraction ratio has been attained by minimizing the maximum normal stress, taking into account the adequate-strength condition. Conversely, the cross-sections of the box profiles for the optimum and maximum subtraction ratios have been optimized by minimizing their cross-section area, accounting for the defined combined strength condition involving adequate- strength and local stability requirements. An equivalent box section design model that allows checking the local stability of the box sections possessing dissimilar wall segment thicknesses has been developed to perform the local buckling control on the designed optimum box sections with unequal wall thicknesses. The new local stability conditions have been defined relying on this developed equivalent box section design model. The analytical results, validated through numerical predictions obtained from linear elastic local buckling and post-buckling analyses performed using Abaqus software, have shown that the optimally designed box section achieves substantial material savings per unit length compared to its corresponding equivalent box section.

On determining structural wall layout during the adaptive reuse process of historic masonry buildings

Defining modifications to a building’s layout during the adaptive reuse of historic masonry buildings can be challenging since the existing structural grid constrains the transformations to be performed. This paper proposes a novel methodology for exploring modifications to a structural wall layout during the adaptive reuse process of historic buildings. The primary objective is to redefine structural wall arrangements to accommodate new openings and/or cuts in existing structural elements, offering designers flexibility in spatial arrangement modifications. Considering that existing buildings are subjected to damage, an evolutionary approach is used to define which wall segments can be removed from the existing layout, according to a multi-objective function that targets minimizing the presence of damaged elements and maximizing the presence of undamaged elements in the design, in addition to minimizing the building’s eccentricity. The problem considers structural constraints based on the compressive capacity and minimum length of shear components. A computational strategy based on Genetic Algorithm is conceptualized as a tool for deriving potential layout solutions that adhere to structural requirements while facilitating the incorporation of new openings. By systematically evolving potential solutions over multiple generations, the algorithm navigates the design space to pinpoint areas within the original shear layout where material can be removed while respecting the given structural constraints. The methodology’s validity is demonstrated through a case study situated in a UNESCO World Heritage Site, providing evidence of the practical application and success of the genetic algorithm approach in real-world scenarios. The findings presented in this paper contribute to the convergence of structural engineering and architectural preservation, offering a systematic and efficient means of determining structural wall layouts for the adaptive reuse of historic masonry buildings. Integrating computational techniques into the adaptive reuse process holds transformative potential, establishing a robust framework for sustainable urban development that honors and enhances the historical fabric of our built environment.

Review: Flow Diversion for the Treatment of Middle Cerebral Artery Aneurysms.

The invention of flow diverting stents (FDS) is a novel milestone in the field of endovascular aneurysm therapy, promoting physiological healing of the vessel segment contrary to prior deconstructive treatment strategies, such as coiling. The effects of FDS are based on changes in flow patterns, segmental wall stabilization, and the growth of a neointima. Although flow diversion is already well established for cerebral aneurysms in proximal segments, peripheral locations remain challenging. Especially the middle cerebral artery (MCA) with its predominance of non-collateralized perforators and functional end arteries that supply the eloquent areas of the brain is of major concern.The literature was reviewed for flow diversion of the MCA and antiplatelet therapy.Resulting from the special anatomical characteristics of the MCA, FDS implantation in this territory is completely different from the proximal vessel segments. Still, flow diversion represents an effective endovascular strategy, especially in otherwise non-accessible or sufficiently treatable lesions. However, the risk of ischemic adverse events might be increased. Special attention to the individual decision regarding device selection, antiplatelet regimen, and exact definition of the proximal and distal landing zone considering the jailed side branches is essential for a good angiographic and clinical outcome. · MCA aneurysms can be sufficiently treated by FDS.. · The anatomic and hemodynamic characteristics of the MCA result in an increased risk of thromboembolism.. · Individual device selection and antiplatelet regimen are essential for treatment success.. · Schüngel M, Wohlgemuth WA, Elolf E et al. Review: Flow Diversion for the Treatment of Middle Cerebral Artery Aneurysms. Fortschr Röntgenstr 2024; DOI 10.1055/a-2343-0046.

Advanced Myocardial MRI Tissue Characterization Combining Contrast Agent‐Free T1‐Rho Mapping With Fully Automated Analysis

BackgroundMyocardial T1‐rho (T1ρ) mapping is a promising method for identifying and quantifying myocardial injuries without contrast agents, but its clinical use is hindered by the lack of dedicated analysis tools.PurposeTo explore the feasibility of clinically integrated artificial intelligence‐driven analysis for efficient and automated myocardial T1ρ mapping.Study TypeRetrospective.PopulationFive hundred seventy‐three patients divided into a training (N = 500) and a test set (N = 73) including ischemic and nonischemic cases.Field Strength/SequenceSingle‐shot bSSFP T1ρ mapping sequence at 1.5 T.AssessmentThe automated process included: left ventricular (LV) wall segmentation, right ventricular insertion point detection and creation of a 16‐segment model for segmental T1ρ value analysis. Two radiologists (20 and 7 years of MRI experience) provided ground truth annotations. Interobserver variability and segmentation quality were assessed using the Dice coefficient with manual segmentation as reference standard. Global and segmental T1ρ values were compared. Processing times were measured.Statistical TestsIntraclass correlation coefficients (ICCs) and Bland–Altman analysis (bias ±2SD); Paired Student's t‐tests and one‐way ANOVA. A P value &lt;0.05 was considered significant.ResultsThe automated approach significantly reduced processing time (3 seconds vs. 1 minute 51 seconds ± 22 seconds). In the test set, automated LV wall segmentation closely matched manual results (Dice 81.9% ± 9.0) and closely aligned with interobserver segmentation (Dice 82.2% ± 6.5). Excellent ICCs were achieved on a patient basis (0.94 [95% CI: 0.91 to 0.96]) with bias of −0.93 cm2 ± 6.60. There was no significant difference in global T1ρ values between manual (54.9 msec ± 4.6; 95% CI: 53.8 to 56.0 msec, range: 46.6–70.9 msec) and automated processing (55.4 msec ± 5.1; 95% CI: 54.2 to 56.6 msec; range: 46.4–75.1 msec; P = 0.099). The pipeline demonstrated a high level of agreement with manual‐derived T1ρ values at the patient level (ICC = 0.85; bias +0.52 msec ± 5.18). No significant differences in myocardial T1ρ values were found between methods across the 16 segments (P = 0.75).Data ConclusionAutomated myocardial T1ρ mapping shows promise for the rapid and noninvasive assessment of heart disease.Evidence Level3Technical EfficacyStage 1

Learning carotid vessel wall segmentation in black-blood MRI using sparsely sampled cross-sections from 3D data.

Atherosclerosis of the carotid artery is a major risk factor for stroke. Quantitative assessment of the carotid vessel wall can be based on cross-sections of three-dimensional (3D) black-blood magnetic resonance imaging (MRI). To increase reproducibility, a reliable automatic segmentation in these cross-sections is essential. We propose an automatic segmentation of the carotid artery in cross-sections perpendicular to the centerline to make the segmentation invariant to the image plane orientation and allow a correct assessment of the vessel wall thickness (VWT). We trained a residual U-Net on eight sparsely sampled cross-sections per carotid artery and evaluated if the model can segment areas that are not represented in the training data. We used 218 MRI datasets of 121 subjects that show hypertension and plaque in the ICA or CCA measuring in ultrasound. The model achieves a high mean Dice coefficient of 0.948/0.859 for the vessel's lumen/wall, a low mean Hausdorff distance of , and a low mean average contour distance of on the test set. The model reaches similar results for regions of the carotid artery that are not incorporated in the training set and on MRI of young, healthy subjects. The model also achieves a low median Hausdorff distance of on the 2021 Carotid Artery Vessel Wall Segmentation Challenge test set. The proposed method can reduce the effort for carotid artery vessel wall assessment. Together with human supervision, it can be used for clinical applications, as it allows a reliable measurement of the VWT for different patient demographics and MRI acquisition settings.

Analysis of the significance of echocardiographic signs of right ventricular dysfunction for predicting the outcome of heart failure with reduced left ventricular ejection fraction

Objective: to determine the ultrasound signs of right heart dysfunction, which increase the prognostic value of the recommended parameters of left ventricular (LV) dysfunction in patients with heart failure with reduced ejection fraction (HFrEF).Materials and methods. The prospective study included 79 patients with HFrEF LV with clinical manifestations of chronic heart failure functional class III according to the New York Heart Association (HF NYHA Class III) in 52 patients (65.8%) and HF NYHA Class IV in 27 (34.1%). The primary end point was death during a follow-up period of up to 3 years while waiting for heart transplantation.Results. Overall mortality was 33 patients (41.7%), 17 (21.5%) during the 1st year of follow-up. Regression analysis revealed the following independent ultrasound predictors of poor prognosis: LV ejection fraction on 3D-echocardiography (3DE LVEF), p = 0.014; global longitudinal strain of the LV (GLS LV), p = 0.010, and of the interventricular septum basal segment (IVSLS BS), p = 0.012; mean longitudinal strain of the basal segment of the right ventricle free wall (FWLS BS RV), p = 0.003. Changes in the configuration and dilatation of the LV cavity, an increase in LV end-diastolic pressure, impaired contractility, and strain of the LV myocardium can affect the function of the right ventricle (RV) through the common interventricular septum (IVS). Dilatation of the RV due to an increase in the end diastolic area (RV EDA) of more than 30 cm2 (p = 0.012) and end systolic area (RV ESA) of more than 25 cm2 (p = 0.001), an increase in the volume of the right atrium (3DE AKI) of more than 100 ml (p = 0.036), and a decrease in the % inspiratory collapse of the inferior vena cava (% IVC) less than 30% (p = 0.005) demonstrated a prognostic significance in the observed patients. A decrease in the deformation properties of the pancreas due to the longitudinal component and impaired strain of the basal segment makes a greater contribution to RV dysfunction (FWLS BS, % &lt; -15% (p &lt; 0.001)).Conclusions. RV dysfunction in patients with HFrEF is an unfavorable prognostic factor, independently associated with existing LV dysfunction. The most significant ultrasound sign for surveillance prediction of patients with LV HFrEF and RV dysfunction are indicators of ventricular myocardial deformation. Remodeling of the right chambers and dysfunction of the RV is a trigger for the separation of the RV and pulmonary artery, which ultimately leads to adverse outcomes.

Myocardial viability under various ischemic burdens in chronic total occlusions: A stress-cardiac magnetic resonance study

ObjectivesThis study aimed to analyze each myocardial segment's ischemic burden, scarring, function, and viability by late gadolinium enhancement (LGE) imaging and stress-MRI using adenosine. Materials and methodsSemi-quantitative and qualitative parameters of myocardial segments were obtained by stress-MRI. Moreover, segments without perfusion defect were defined as the no ischemic group, segments with a perfusion defect of ≤50% were defined as a low ischemic burden group, and segments with a perfusion defect of >50% were defined as a high ischemic burden group. “Segmental wall thickening (SWT)” was defined as the absolute difference between the end-diastolic and end-systolic wall thickness. Finally, viability was defined by dysfunctional myocardium (<3 ​mm segmental wall thickening [SWT]) and ≤50% late gadolinium enhancement (LGE). ResultsA total of 445 segments in the CTO territory were analyzed, scar tissue was found in the CTO territory, with LGE evident in 18.2% of CTO segments totaling >50%. Among the different ischemic burden groups, there were significant differences in LGE volume (p ​< ​0.01), and the trend of SWT was consistent with the degree of myocardial ischemia. The incidence of ≤50% LGE and viable myocardium was higher in segments of the no ischemia and low ischemic burden groups. However, there was no significant difference in the incidence of dysfunctional myocardial segments among the three groups (P ​> ​0.05). ConclusionsStress MRI parameters can accurately and detailly assess myocardial viability and function, so multi-parameter joint assessment of CTO patients by stress MRI may help in treatment decisions.

Downregulation of RIP3 ameliorates the left ventricular mechanics and function after myocardial infarction via modulating NF-κB/NLRP3 pathway.

Adverse cardiac mechanical remodeling is critical for the progression of heart failure following myocardial infarction (MI). We previously demonstrated the involvement of RIP3-mediated necroptosis in the loss of functional cardiomyocytes and cardiac dysfunction post-MI. Herein, we investigated the role of RIP3 in NOD-like receptor protein 3 (NLRP3)-mediated inflammation and evaluated the effects of RIP3 knockdown on myocardial mechanics and functional changes after MI. Our findings revealed that mice with MI for 4 weeks exhibited impaired left ventricular (LV) myocardial mechanics, as evidenced by a significant decrease in strain and strain rate in each segment of the LV wall during both systole and diastole. However, RIP3 knockdown ameliorated cardiac dysfunction by improving LV myocardial mechanics not only in the anterior wall but also in other remote nonischemic segments of the LV wall. Mechanistically, knockdown of RIP3 effectively inhibited the activation of the nuclear factor kappa-B (NF-κB)/NLRP3 pathway, reduced the levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18) in the heart tissues, and mitigated adverse cardiac remodeling following MI. These results suggest that downregulation of RIP3 holds promise for preventing myocardial inflammation and cardiac mechanical remodeling following MI by regulating the NF-κB/NLRP3 pathway.

Theory and experimental discussion of synchronous backfilling self-compacting concrete technology behind the segment wall of double-shield TBM

The conventional method of urban subway tunnel excavation using a double-shield tunnel boring machine (DS-TBM) typically involves a two-stage backfilling process behind the segment wall using pea gravel and grouting. However, this method has inherent drawbacks such as uneven backfilling of pea gravel and delayed grouting, which can lead to structural issues such as segment dislocation, damage, and groundwater leakage during tunnel excavation. To address these problems, this study proposes a technical theory of synchronous backfilling self-compacting concrete backfilling material (SCCBM), considering the limitations of the conventional DS-TBM backfill method. This theory uses a specially designed wear-resistant seal plate suitable for a DS-TBM shield tail. The optimal proportion of SCCBM for backfilling the segment wall was determined based on Okamura's empirical method using anti-dispersion powder, fine stones (1–5 mm particle size), and coarse stones (5–10 mm particle size) as the basic materials. The SCCBM was designed and evaluated using various test methods, including the mini-slump, standard slump flow, standard L-box, and improved L-box tests. The engineering characteristics of the backfill material, such as initial setting time, blocking ability ratio, stone rate, and axial compressive strength, were considered during the evaluation. The results demonstrate that all indicators meet the standards for backfilling behind subway tunnel segment walls. Furthermore, an on-site synchronous backfilling SCCBM experiment was conducted to validate the feasibility and advantages of the new synchronous backfilling technology. The experiment involved observing the complete backfill process and monitoring the vertical displacement of the segment. Through these observations, the practicality and benefits of the proposed synchronous backfilling technology were confirmed.

Effect of flexible membrane in triaxial test on the mechanical behaviour of rockfill material using Discrete Element Method

The investigation of rockfill materials poses challenges due to their large particle size, associated high cost, and long laboratory testing duration. As a result, empirical correlations based on historical experimental studies are commonly used to design and analyse rockfill structures. However, the extensive use of rockfill in a wide range of applications and limited understanding of its mechanical behaviour emphasize the need for further research. These make it necessary to develop a robust technique capable of capturing key parameters such as particle shape and breakage, allowing for the simulation and study of large-scale assemblies with realistic boundary conditions. Given that the behaviour of rockfill is highly scale-dependent, primarily due to particle breakage, the simplified laboratory tests on the scaled-down assemblies can be misleading. Particle breakage is a fundamental phenomenon in the mechanical behaviour of rockfill and significantly affects shear strength, deformability, and porosity under different stress levels. The particle breakage is influenced by factors such as the rockfill’s maximum particle size, mineralogy, particle shape, gradation, and confining stresses. This study adopts a computationally efficient breakage method called the Modified Particle Replacement Method (MPRM) based on the Discrete Element Method. A Tile-Based Flexible Membrane (TBFM) for triaxial test modelling has been developed by employing segmental rectangular walls to create a deformable membrane. The effects of critical parameters, including particle shape, confining stress, membrane resolution, degree of flexibility, and the characteristic strength of the particles, are examined. The findings of the combined MPRM-TBFM approach demonstrate the significant influence of membrane flexibility on volumetric-related behaviour.Graphical