Stages Of Damage Research Articles

Quantitative investigation on localized deformation process of rocks by uniaxial test and digital image correlation

Determining the localized deformation mechanism is of vital importance to understand the failure processes of geomaterials in practical engineering. In this study, uniaxial monotonic and cyclic loading tests of slate samples were conducted and the failure processes were recorded by using the AE system and digital image correlation (DIC). The results show that the deformation field variance increases significantly in the initiation of the macro-scale failure stage. Under cyclic loading, the shape of the stress-variance hysteresis curve varies with increasing upper limit stress, and four types of stress-variance hysteresis curves were revealed. Increasing lag time of variance indicates gradual accumulation of damage to the sample. The comprehensive analysis of the evolution process of damage variables defined by cumulative AE counts and variance reveals that the rock failure process can be divided into crack closure stage, initial damage stage, stable development stage, accelerated development stage and failure stage. By proposing the differentiation rate, it is found that there are apparent failure precursor points under monotonic and cyclic loading.

Insights into mechanical property and damage evaluation of a novel waste-based coal gangue-filled backfill

The cemented backfill is a multi-phase cementitious composite material, which is widely used in the backfilling industry of mined-out areas. To investigate the mechanical properties and damage mechanism of a novel waste-based coal gangue-filled backfill (CGFB) under the action of overburdened rock, in this study, the uniaxial compressive test and microscopic analysis were conducted, the damage process of CGFB samples under loading was monitored by the acoustic emission (AE) technique. The results show that the compressive strength of CGFB samples mainly depends on the mechanical behavior of the cement-tailings grout (CTG) and the microscopic features of the interfacial transition zone (ITZ) between the coal gangue (CG) aggregate and CTG matrix. The response of ringing counts and AE energy to the development of stress shows a clear time-varying response law. The b-value results reveal the macro and micro-crack development of the CGFB samples during different damage stages. The tensile failure predominates in the failure process according to the analyses of average frequency (AF) and RA (Risetime/ Amplitude) values. The damage variable increases slowly first and then develops rapidly with the increasing stress. The failure modes of CGFB samples with low water-to-cement (w/c) ratios were CG aggregates and ITZ damage, while ITZ damage was dominant for those with high w/c ratios. The results of the study can provide a theoretical basis for the reinforcement and modification of the novel CGFB material.

Analysis of Electrical Resistivity Characteristics and Damage Evolution of Soil-Rock Mixture under Triaxial Shear.

Construction of engineering structures in geomaterials with soil-rock mixture (S-RM) is often a challenging task for engineers. When analyzing the stability of the engineering structures, the mechanical properties of S-RM often receive the most attention. To study the mechanical damage evolution characteristics of S-RM under triaxial loading conditions, a modified triaxial apparatus was used to conduct shear test on S-RM, and the change of electrical resistivity was measured simultaneously. The stress-strain-electrical resistivity curve and stress-strain characteristics under different confining pressures were obtained and analyzed. Based on the electrical resistivity, a mechanical damage model was established and verified to analyze the damage evolution regularities of S-RM during shearing. The results show that the electrical resistivity of S-RM decreases with increasing axial strain and that the differences in decrease rates correspond to the different deformation stages of the samples. With the increase in loading confining pressure, the stress-strain curve characteristics change from a slight strain softening to a strong strain hardening. Additionally, an increase in rock content and confining pressure can enhance the bearing capacity of S-RM. Moreover, the derived damage evolution model based on electrical resistivity can accurately characterize the mechanical behavior of S-RM under triaxial shear. Based on the damage variable D, it is found that the damage evolution process of S-RM can be divided into a non-damage stage, a rapid damage stage and a stable damage stage. Furthermore, the structure enhancement factor, which is a model modification parameter for the effect of rock content difference, can accurately predict the stress-strain curves of S-RMs with different rock contents. This study sets the stage for an electrical-resistivity-based monitoring method for studying the evolution of internal damage in S-RM.

Association between trajectories in cardiac damage and clinical outcomes after transcatheter aortic valve replacement

BackgroundThere is little evidence of evolution in cardiac damage after transcatheter aortic valve replacement (TAVR) in aortic stenosis (AS) patients. Less is known about the prognostic value and potential utility of different cardiac damage trajectories following TAVR. ObjectivesThis study aims to investigate the cardiac damage trajectories following TAVR and explore their association with subsequent clinical outcomes. MethodsAS patients undergoing TAVR were enrolled and classified into five cardiac damage stages (0–4) based on the echocardiographic staging classification retrospectively. They were further grouped into early stage (stage 0–2) and advanced stage (stage 3–4). The cardiac damage trajectories in TAVR recipients were evaluated according to their trend between baseline and 30 days after TAVR. ResultsA total of 644 TAVR recipients were enrolled, with four distinct trajectories identified. Compared to patients with early-early trajectory, patients with early-advanced trajectory were at 30-fold risk of all-cause death (HR 30.99, 95% CI 13.80–69.56; p < 0.001). In multivariable analyses, early-advanced trajectory was associated with higher 2-year all-cause death (HR 24.08, 95% CI 9.07–63.90; p < 0.001), cardiac death (HR 19.34, 95% CI 3.06–122.34; p < 0.05), and cardiac rehospitalization (HR 4.19, 95% CI 1.49–11.76; p < 0.05) after TAVR. ConclusionsThis investigation provided insight into four cardiac damage trajectories in TAVR recipients and confirmed the prognostic value of distinct trajectories. Early-advanced trajectory was associated with poor clinical prognosis following TAVR.

Meso-damage analysis of concrete based on X-ray CT in-situ compression and using deep learning method

Traditional concrete failure research mostly based on surface cracks to analyze its macro mechanical properties, which cannot obtain the internal structure and failure process on a mesoscopic level. The internal topography of concrete can be acquired by using X-ray CT to scan the entire concrete specimen, and the internal structure change caused by stress can be captured when combined with an in-situ CT loading device. Thus, in-situ X-ray computed tomography (X-ray CT) scanning was performed on concrete under uniaxial compression, and the real-time CT images of the meso-damage evolution process inside concrete were obtained. Deep Learning method was applied to extract two-dimensional (2D) and three-dimensional (3D) cracks for visual analysis and quantitative characterization. The damage evolution process, damage variables and Poisson's ratio of concrete were analyzed based on CT values. The results revealed that crack formation and propagation did not necessarily occur at the interface, the low-density area was prone to cause concrete damage. The crack morphology obtained by deep learning was highly consistent with the distribution of cracks in concrete. The law of crack extension, distribution and expansion could be represented through crack thickness, crack voxel number and crack area. The initial meso-damage distribution of concrete had an important impact on the occurrence of localized damage. The results of CT value showed that the meso-damage of concrete develops from inside-out. The damage evolution process was divided into compression stage Ⅰ, damage stage Ⅱ and destruction stage Ⅲ. The damage variable and Poisson's ratio were evaluated by CT value could further characterize the deterioration degree of concrete.

Experimental visualization of the wear and scuffing evolution of a flake graphite cast iron cylinder liner

Scuffing is a wear mechanism that can lead to catastrophic failure of various technical applications. Even though the mechanism has been researched in countless publications for decades, it is not fully understood yet. An experimental approach was used in this paper to investigate the origin and evolution of scuffing in a ring-on-liner contact. For this purpose, test runs in an application-oriented test rig were stopped at different points in time. A linear tribometer was used to transfer a reciprocating motion of a real piston ring segment to a specimen made from a real cylinder liner. Based on a comprehensive analysis, a four-stage scuffing hypothesis for a ring-on-liner contact was developed. In the first stage, smearing of the honing structure and the formation of surface cracks lead to the development of a scaly structure on the liner surface. Crack growth induced by adhesive shear forces leads to the formation of breakouts in the liner surface in the second stage. Both stages are stable and only the specific load increase of the used test strategy causes the transition to stage three. Here, large crack growth induced breakouts result in the local destruction of tribofilms and, subsequently in local metallic contact between the specimens. When this local destruction becomes rampant and expands to a macro scale, adhesive bonds lead to macroscopic scuffing. It can be deduced that the first occurring damage stage is a result of a surface fatigue process.

Failure process and tensile stiffness of shield tunnel with reinforced concrete inner lining under internal water pressure

Shield method have been commonly used in water conveyance tunnels. To improve the bearing capacity of a shield tunnel under internal water pressure, a reinforced concrete lining is constructed inside the segmental linings to form a composite lining structure. However, cracks typically occur in reinforced concrete inner linings. In this study, a prototype test was performed to investigate the failure process of a composite lining. Based on the test observations, the progressive failure process of the composite lining experienced four stages. In the elastic stage, the stress and deformation of the composite lining increased linearly with the internal pressure, and no cracks appeared. In the cracking stage, cracks first occurred in the inner lining near the joints and were subsequently uniformly distributed along the circumferential direction. In the joint damage stage, the cracking of the inner lining caused more internal pressure to transmit to the segmental lining. As the internal pressure increased, compressive damage occurred in the handholes of the segmental joints. Finally, in the failure stage, the damage to the joints deteriorated and more internal pressure was borne by the rebar of the inner lining. Shear failure typically occurred at the welding point of the inner-lining rebar, followed by joint fracture near the welding point. Finally, the composite lining lost its ability. The test results showed that cracking of reinforced concrete inner lining remarkably decreased the tensile stiffness of composite lining. Consequently, the joint opening and convergence of the tunnel developed at a higher rate, posing a threat to the operational safety of the tunnel. The tensile stiffness is a key factor related to the deformation and bearing capacity of a shield tunnel. Therefore, an analytical solution was established to calculate the tensile stiffness of the composite lining after cracking. The analytical solution matched the test results well. In addition, the effects of the thickness and reinforcement ratio of the inner lining were analysed. The results suggested that increasing the reinforcement was more beneficial in improving the tensile stiffness of the composite lining.

Seismic Vulnerability Analysis of Multi-main-span High Pier Continuous Rigid-frame Bridge in Terms of Cloud Method

Due to the complex canyon topography in southwestern regions of China, several multi-main-span high pier continuous rigid-frame bridges (MHPCRFBs) are built to meet the special terrain. Owing to the great effect of high-order modes, the seismic responses of MHPCRFBs are more complicated than the conventional signal main span continuous rigid-frame bridges. However, there has been very limited researches focus on the seismic vulnerability of MHPCRFBs. This study selects a practical five-span (three main span) high pier continuous rigid-frame bridge as a study object to investigate the seismic vulnerability of MHPCRFBs under near-field pulse-like seismic wave excitation. And a finite element model of the example bridge is built by OpenSees incorporating the influence of abutment, and simultaneously 100 near-field pulse-like seismic waves are chosen to research their effect on the seismic vulnerability of the MHPCRFB. The dynamic nonlinear time-history analyses are carried out to record the peak demand values of the example bridge under three seismic excitation calculation cases (longitudinal earthquake, biaxial earthquake, and triaxial earthquake). Thirty-three intensity measures are compared with respect to two statistical parameters including correlation efficient and root mean square error, the peak ground velocity (PGV) turns out to be the optimal intensity measure for seismic vulnerability analysis of MHPCRFB. Subsequently, by using the analysis procedures of the cloud method, the seismic vulnerability curves of MHPCRFB are developed and compared. The results of this study show that the bottom and top areas of the high piers are more fragile at the slight and moderate damage stages along longitudinal direction, and only the bottom areas are prone to damage along transverse direction. And the seismic wave excitation directions have an obvious influence on the seismic damage probability of the MHPCRFB. In addition, the zone with larger failure probabilities of the lower pier is significantly longer than the higher pier. The obtained results provide helpful reference for the seismic-resistant design and consolidation of MHPCRFBs, shed light on the lower pier of MHPCRFBs should be paid high concern to the anti-seismic design.

Morphological prediction of lethal outcomes in the evaluation of lung tissue structural changes in patients on respiratory support with СOVID-19: Ukrainian experience.

The impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on lung tissue in patients on respiratory support is of significant scientific interest in predicting mortality. This study aimed to analyze post-mortem histological changes in the lung tissue of COVID-19 patients on respiratory support using vital radiology semiotics. A total of 41 autopsies were performed on patients who died of SARS-CoV-2 and had confirmed COVID-19 by polymerase chain reaction (PCR) and radiological evidence of lung tissue consolidation and ground glass opacity. The results showed that the duration of COVID-19 in patients on respiratory support was significantly associated with the development of all stages of diffuse alveolar damage, acute fibrous organizing pneumonia, pulmonary capillary congestion, fibrin thrombi, perivascular inflammation, alveolar hemorrhage, proliferating interstitial fibroblasts, and pulmonary embolism. The prediction model for lethal outcomes based on the duration of total respiratory support had a sensitivity of 68.3% and a specificity of 87.5%. In conclusion, for COVID-19 patients on long-term respiratory support with radiological signs of ground glass opacity and lung consolidation, post-mortem morphological features included various stages of diffuse alveolar lung damage, pulmonary capillary congestion, fibrin clots, and perivascular inflammation.

Transcriptional Characterization of Bronchoalveolar Lavage Fluid Reveals Immune Microenvironment Alterations in Chemically Induced Acute Lung Injury.

Chemically induced acute lung injury (CALI) has become a serious health concern in our industrialized world, and abnormal functional alterations of immune cells crucially contribute to severe clinical symptoms. However, the cell heterogeneity and functional phenotypes of respiratory immune characteristics related to CALI remain unclear. We performed scRNA sequencing on bronchoalveolar lavage fluid (BALF) samples obtained from phosgene-induced CALI rat models and healthy controls. Transcriptional data and TotalSeq technology were used to confirm cell surface markers identifying immune cells in BALF. The landscape of immune cells could elucidate the metabolic remodeling mechanism involved in the progression of acute respiratory distress syndrome and cytokine storms. We used pseudotime inference to build macrophage trajectories and the corresponding model gene expression changes, and identified and characterized alveolar cells and immune subsets that may contribute to CALI pathophysiology based on gene expression profiles at single-cell resolution. The immune environment of cells, including dendritic cells and specific macrophage subclusters, exhibited increased function during the early stage of pulmonary tissue damage. Nine different subpopulations were identified that perform multiple functional roles, including immune responses, pulmonary tissue repair, cellular metabolic cycle, and cholesterol metabolism. Additionally, we found that individual macrophage subpopulations dominate the cell-cell communication landscape. Moreover, pseudo-time trajectory analysis suggested that proliferating macrophage clusters exerted multiple functional roles. Our findings demonstrate that the bronchoalveolar immune microenvironment is a fundamental aspect of the immune response dynamics involved in the pathogenesis and recovery of CALI.

MiR-21 alleviates renal tubular epithelial cells injury induced by ischemia by targeting TLR4

Renal ischemia is the initial stage of kidney damage, leading to mitochondrial metabolism disorders and cell necrosis. In this study, we aimed to investigate the biological functions and potential mechanisms of miR-21 in protecting renal tubular epithelial cells from oxidative stress and apoptosis following oxygen glucose deprivation (OGD). Following an OGD injury, miR-21 levels increased in HK-2 renal tubular epithelial cells. Overexpression of miR-21 decreased the protein expressions of cleaved caspase-3, BAX, P53, cell apoptosis and increased Bcl-2 expression in HK-2 cells with OGD injury. In vivo studies found that miR-21 agomir reduced renal tissue apoptosis, while miR-21 antagomir increased it. In addition, overexpression of miR-21 reduced levels of reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) in HK-2 cells with OGD injury. However, miR-21 inhibition exhibited the opposite effect. A dual-luciferase reporter assay demonstrated that miR-21 directly regulates Toll-like receptor 4 (TLR4) by targeting the 3′-UTR of TLR4 mRNA. Overexpression of miR-21 led to decreased TLR4 protein expression, and TLR4 knockdown was shown to greatly increase AKT activity in HK-2 cells by in vitro kinase assay. Additionally, TLR4 knockdown promoted AKT phosphorylation and hypoxia-inducible factor-1α (HIF-1α) expression, while TLR4 overexpression inhibited these processes. Furthermore, AKT activation abolished the effect of TLR4 on HIF-1α, while AKT inhibition decreased the expression of TLR4 on HIF-1α in TLR4 knockdown HK-2 cells. Further study revealed that HIF-1α inhibition abolished the protective effect of miR-21 overexpression on ROS, LDH levels and cell apoptosis in HK-2 cells after OGD injury, which is indicated by increased levels of ROS and LDH, as well as increased cell apoptosis after HIF-1α inhibition in miR-21-treated HK-2 cells. In conclusion, miR-21 defends OGD-induced HK-2 cell injury via the TLR4/AKT/HIF-1α axis.

Developing assessment flow for damage estimation of mud housing typology through a case study against coastal floods

Rising instances of prolonged inundation due to climate-aggravated high tide flooding are economically burdensome for resource-crunched developing nations that bear enormous damage due to loss of built infrastructure (housing in this case). Regardless of the loss, coastal flood impact on buildings is rarely given precedence. The mud building typology in India captures 34% of existing housing demand primarily within ruralIndia; for instance, 75% of the housing in Sagar Island uses mud as the dominant construction material, making it an ideal case for the proposed research. The multivariate nature of damage and empirical data constraint associated with mud buildings propels the development of two unconventional damage assessment approaches using multivariate-probabilistic technique. The proposed literature-based approach uses logical reasoning based on the available scientific evidence whereas the lab-based approach uses the insights from structural analysis of scaled model. The damage matrix created from both the approaches are used to analyse a common flood data (depth & duration) generated using 1000 Montecarlo simulations. The resultant Damage Stage values confirm the versatility of either approach over spatial (local to regional)—temporal (flood character and intensity) dimensions. The lab-based approach proved to be a better alternative considering the availability of continuous records on damage behaviour and precise information on the flood threshold of dominant building material, a crucial component of the multivariate damage assessment process.

At room temperature, the impact of strain rates on the damage of CVPC compound

The demand of polymers has been increasing over the past decade, due to their specific properties. This large use leads mechanical engineers to study material damage problems. Partial or total ruptures resulting from these problems frequently cause accidents. Unfortunately, such incidents occur frequently due to insufficient understanding of the operating conditions or the types of damage. This paper presents the impact of strain rate on the damage of chlorinated polyvinyl chloride compounds. Tensile tests were conducted on the samples at room temperature with three strain rates (5, 50, and 500 mm/min). The results of the tests are used to develop two damage models for this polymer: the first one generated through static damage and the second one acquired via the use of unified theory. Both models are constructed on the concept of stress. The results clearly obtained from these two models enable us to describe the mechanical comportment of chlorinated polyvinyl chloride and to forecast how the damage will develop. Moreover, three stages of damage are identified to assist predictive maintenance in defining the material CPVC's safety and maintenance intervals.

A graph‐based method for quantifying crack patterns on reinforced concrete shear walls

AbstractThis paper presents an innovative method to quantify damage based on surface cracks of reinforced concrete shear walls (RCSWs). The key idea is to use artificial intelligence and convert crack patterns to graphs. In this method, the mathematics of graph theory is used to extract information (graph‐based features) from crack patterns and use them for crack quantification. The proposed graph features are used in linear regression and leave‐one‐out cross‐validation to predict the mechanical features calculated for each RCSW: Park and Ang damage index and the dissipated energy. Among the three general stages of damage, which are safe, questionable, and not safe, this paper focuses on quantifying the second stage. To validate the approach, crack images of three RCSWs are used. The walls had different aspect ratios (0.54, 0.94, and 2.00) and were subject to quasi‐static cyclic loading. Regression results demonstrate low root mean squared errors and high coefficients of determination (R2 scores above 0.845). This proves the ability of the proposed graph‐based method in quantifying damage based on surface crack patterns.

Bending-damaged fracture criterion and numerical implementation of limestone beam under three-point bending test

To study the characteristics of tensile cracking by rock-bending damage, the bending stress–strain curves and the cumulative ringing counts were obtained by a three-point bending test and acoustic emission (AE) monitoring of limestone beams. Based on the Lemaitre strain equivalent principle and the continuous damage theory, the bending damage variable D was defined by the AE cumulative ringing counts, and the bending crack damage evolution equation was established according to the Weibull distribution of the rock element strength. To realize the numerical test of the bending deformation, the damage variable D was used as the intermediate variable, and the specific process of damage bending stress transformation and the realization of the tensile crack criterion were secondary developed by FISH language in FLAC3D. According to the results, the central part of rock beam deforms downward under the action of bending stress, and both ends tilt up. Therefore, the bending failure begins with the tensile crack at the bottom of the rock beam and gradually extends to the compression zone. The maximum damage value is about 0.402 before the peak stress. The compressive stress in the x direction increases from the neutral layer to the top of the rock beam, and the tensile stress in the x direction increases from the neutral layer to the bottom of the rock beam. The maximum tensile stress is distributed in the center of the bottom of the specimen, where the bending effect is obvious. The stress–time curve was divided into the (Ⅰ) compaction stage, (Ⅱ) expansion stage, and (Ⅲ) penetration stage, accordingly, and the evolution of damage equation was divided into three stages: initial damage stage, slow damage stage, and accelerated damage stage. The curves of the experimental result, theoretical model prediction result, and numerical simulation result were in good agreement with each other, which indicates that the numerical simulation based on the criterion of rock damaged fracture can better reflect the bending process of rock beams under three-point bending stress.

Stress-induced AE varying characteristics in distinct lithologies subjected to uniaxial compression

This study conducted uniaxial compression acoustic emission (AE) tests on four typical rocks with different lithologies, including coal, limestone, gypsum, and shale. In addition to measuring their stress-induced deformation process and associated AE time-varying response, this work emphatically discussed the differences in mechanical properties, fracture modes, spatial-temporal evolution, frequency band energy distribution, and nonlinear characteristics of stress-induced AE signals. According to the results, the AE energy released during the loading process and the total energy at the peak stress are closely related to the rock strength. The main microcracking fractures of coal and limestone are mixed mode with both shear and tensile components, while those of gypsum and shale are mainly tensile axial-splitting failures. The AE locations of those four tested rocks correspond to their macroscopic rupturing morphology respecitively, but with different occurrence times and spatial distributions. Additionally, the stress-induced AE events of coal, gypsum, and shale are relatively less during the pre-peak loading stages, while that of limestone begins to become frequent and reach its maximum in the crack extension damage stage. The AE frequency band energy distribution, calculated by wavelet packet decomposition, of limestone is smaller than coal, gypsum, and shale, suggesting that limestone has a larger microfracture scale than the other three rocks. However, it should be noted that approximately 90% of the energy band distribution of these four lithologies is less than 150 kHz. Besides, the nonlinear Hurst index of AE signals is greater than 0.5 when the specimens are loaded around 99% pre-peak stress. This suggests a long-term correlation between acoustic response and the loading process, with a more pronounced increase in the AE signal during the stage close to the catastrophic failure stage. The above findings provide valuable insights into the failure mechanisms of different rocks, contributing to the theoretical framework for preventing and controlling rock engineering disasters.

20-year Results of a 3D Titanium Mesh Coating Stability of 31 Artificial Cups.

The aim of this work was to demonstrate the bony bond strength and resilience of a three-dimensional titanium mesh coating of an artificial acetabulum produced using the diffusion bonding technique. Under the extreme conditions ranging from abrasion-related osteolysis to acetabular perforation, the degree of residual bone and the integrity of the coating were determined. The remaining zones of the (still) stable bone connection are inevitably exposed to a greater load of the layer adhesion between the titanium mesh and the core shell. The investigation was intended to provide information about the stages of damage according to Paprosky in which it was still justifiable to leave the implant in place and simply change the inlay from the purely material-technical point of view of a stable coating. The bond between bone and implant was examined with regard to a possible retention of the implant for its adaptive remodeling up to 27 years. In a retrospective study, 31 explanted human acetabular cups of the Harris-Galante II type, with an average lifetime of 19.7 years (11-27 years), were examined by means of digital area measurement to determine both the bone areas remaining on the coating and the damaged areas of the titanium mesh. Periacetabular bone loss was recorded in a modified Paprosky (PAP) damage classification. Full hemispherical sections of 4 acetabular cups with a life time of 16, 20, 22 and 27 years were examined histopathologically using the diamond cut technique. The periacetabular bone loss resulted in damage class PAP I in 8 cases, PAP IIa in 7 cases, PAP IIb in 2 cases, PAP IIc in 9 cases, PAP IIIa in 3 cases and PAP IIIa in 2 cases PAP IIIb. The average amount of bone that was still firmly attached to the coating after explantation was 17% (0-70%) of the total cup surface. Paprosky I accounted for 44.1%, and PAP IIa and IIb stadiums together a total of 17.1%. The average bone fraction of the implants no longer anchored in the host bed at stages IIc, IIIa and IIIb was 2%. The average coating damage was 11% (0-100%) and was exclusively attributable to the unstable implants of stages IIc, IIIa and IIIb. The histopathological findings showed adaptive bone remodeling, that was detectable for up to 27 years through the titanium mesh down to the interface with the solid acetabular core. The titanium wire mesh was mostly surrounded by lamellar, mature bone. The results show that the connection between the Tivanium cup and the previously oldest and unchanged sintered coating - in the form of a three-dimensional titanium mesh applied in point and line contact - is very load-resistant even under the extreme loads of periacetabular osteolysis and cup perforations. Since there was no damage to the coating in periacetabular damage stages Paprosky I, IIa and IIb, it is justifiable in these damage stages to leave the implant in situ and to continue to use it with sole replacement of the inlay, but leaving the socket shell. The third-generation acetabular cup (Trilogy) with unchanged three-dimensional titanium mesh coating has been implanted in over 1.2 million cases for 26 years. After a long service life, an increasing number of wear and tear conditions can be expected in today's mostly elderly and vulnerable patient clientele. In view of the results presented here, the early detection of damage would make it possible to avoid costly and stressful explantation of the entire acetabular cup in favor of replacing the sole inlay in Paprosky stages I, IIa and IIb.

Determination of Relative Weightings for Sacroiliac Joint Pathologies in the OMERACT Juvenile Arthritis Magnetic Resonance Imaging Sacroiliac Joint Score

This study aims to determine the relative weights (point value) of items of the juvenile idiopathic arthritis magnetic resonance imaging-sacroiliac joint scoring system (JAMRIS-SIJ). An adaptive multicriteria decision analysis was performed using the 1000Minds web application to determine the relative weights of the items in the JAMRIS-SIJ inflammation and damage domains. Experts in imaging and rheumatology independently completed a conjoint analysis survey (CAS) to determine the point value of the measurement items of the JAMRIS-SIJ. Each CAS survey question asked the expert to compare two hypothetical patient profiles, which were otherwise similar but different at two items at a time, and to select which item showed a more severe stage of inflammation or osteochondral damage. In addition, experts ranked 14 JAMRIS-SIJ grade only or image + grade patient vignettes while blinded to the CAS-derived weights. The validity of the weighted JAMRIS-SIJ was tested by comparing the expert CAS-weighted score and the image + grade ranking method. Seventeen experts completed the CAS (11 radiologists and 6 rheumatologists). Considering the point value for inflammation domain items, osteitis (24.7%) and bone marrow edema (24.3%) had higher group-averaged percentage weights compared to inflammation in erosion cavity (16.9%), joint space enhancement (13.1%), joint space fluid (9.1%), capsulitis (7.3%), and enthesitis (4.6%). Similarly, concerning the damage domain, ankylosis (41.3%) and erosion (25.1%) showed higher group-averaged weights compared to backfill (13.9%), sclerosis (10.7%), and fat metaplasia lesion (9.1%). The Spearman correlation coefficients of the CAS-weighted vignette order and unweighted JAMRIS-SIJ grade only order vignettes for all experts were 0.79 for inflammation and 0.80 for damage. The correlations of image vignettes among imaging experts to CAS were 0.75 for inflammation and 0.90 for damage. The multicriteria decision analysis identified differences in relative weights among the JAMRIS-SIJ measurement items. The determination of the relative weights provided expert-driven score scaling and face validity for the JAMRIS-SIJ, enabling the future evaluation of its longitudinal construct validity.

Mechanical properties evaluation of sustainable engineered cementitious composites containing recycled fine powders

Recycled fine powder (RFP) can be used as supplementary cementitious material or fine aggregate in concrete to reduce environmental pollution. This work investigated the mechanical properties of sustainable engineering cementitious (RFP-ECCs) with concrete and brick mixed powder (RMP) and recycled glass powder (RGP). The fresh flowability, hydrate heat, mechanical properties and the microstructure of RFP-ECC were investigated. It was found that the introduction of RGP improved the flowability of the fresh paste without PE fibre, while tiny effect on that of the fresh paste with PE fibre. A higher RGP substitution ratio resulted in a decrease in the hydration rate and the accumulated heat release of RFP-ECC. However, hydration rate and accumulated heat release of binders are not affected by the particle size of RGP. The compressive strength and flexural strength decreased with the increase of RGP substitution ratio. All specimens presented excellent deformation ability and multi-cracking behaviour under flexural loading. The mid-span deflection at peak load of RFP-ECC increased with RGP% but decreased with increasing RGP particle size (0–300 μm). SEM results show that the use of RGP will lead to loosen microstructures of RFP-ECC samples and deteriorate the bonding properties between the fibre and the matrix, resulting in an increased probability of fibre pull-out. The flexural toughness of RFP-ECC during the deformation-hardening stage and damaging stage were evaluated by introducing equivalent flexural toughness ratio and residual flexural toughness ratio. Finally, the cost assessments and environmental impact facts of RFP-ECC indicate that the utilization of RMP and RGP in ECC mixtures is sustainable and economical.

Ischemia Reperfusion Injury Induced Blood Brain Barrier Dysfunction and the Involved Molecular Mechanism.

Stroke is characterized by the abrupt failure of blood flow to a specific brain region, resulting in insufficient supply of oxygen and glucose to the ischemic tissues. Timely reperfusion of blood flow can rescue dying tissue but can also lead to secondary damage to both the infarcted tissues and the blood-brain barrier, known as ischemia/reperfusion injury. Both primary and secondary damage result in biphasic opening of the blood-brain barrier, leading to blood-brain barrier dysfunction and vasogenic edema. Importantly, blood-brain barrier dysfunction, inflammation, and microglial activation are critical factors that worsen stroke outcomes. Activated microglia secrete numerous cytokines, chemokines, and inflammatory factors during neuroinflammation, contributing to the second opening of the blood-brain barrier and worsening the outcome of ischemic stroke. TNF-α, IL-1β, IL-6, and other microglia-derived molecules have been shown to be involved in the breakdown of blood-brain barrier. Additionally, other non-microglia-derived molecules such as RNA, HSPs, and transporter proteins also participate in the blood-brain barrier breakdown process after ischemic stroke, either in the primary damage stage directly influencing tight junction proteins and endothelial cells, or in the secondary damage stage participating in the following neuroinflammation. This review summarizes the cellular and molecular components of the blood-brain barrier and concludes the association of microglia-derived and non-microglia-derived molecules with blood-brain barrier dysfunction and its underlying mechanisms.