Structural Damage Research Articles

UV light-triggered fluorescence corrosion sensing coatings for AA2024-T3 based on 8-hydroxyquinline loaded vanadium oxide nanorods

Fluorescent corrosion indicators potentially locate the underlying corrosion on metallic substrates based on sensing metal ions caused by corrosion reactions. Nanoparticles loaded with indicators are significant components of the fluorescence corrosion detection system. These fluorescent coatings face challenges (including fluorescence quenching, sluggish response rate, and expensive instrumentation). To tackle such issues, we have developed 8-hydroxyquinoline (8-HQ) loaded oxygen-deficient vanadium oxide (VOx) nanorods (∼220 nm in length and ∼50 nm in width) via solvothermal technique yielding enhanced fluorescence efficiency. 8-HQ/VOx/Ac2403 was utilized to develop a fluorescent corrosion sensing coating for AA2024-T3. The system is designed to detect corrosion within the first few days to weeks after exposure to corrosive conditions by making a complex by reacting with metal ions (Al3+), resulting in a reduction and bright blueish fluorescence effect in the exposure of UV light and can be seen with the naked eye. As a result, fluorescent corrosion-sensing coatings provide a practical substitute for typical coatings to satisfy rising industrial demands by providing corrosion sensing before significant structural damage occurs.

Revenue assessment of damage aware wind farm control for secondary frequency regulation provision

Abstract In this paper, a case study of a wind power plant participating in the balancing market is presented and any potential revenue benefits are estimated. To make a representative performance assessment, an existing case for the frequency regulation market is selected, based on the pay-for-performance scheme of the US regional transmission operator Pennsylvania-New Jersey-Maryland (PJM). In this implementation, the wind power plant is being rewarded or penalized based on its signal-tracking capabilities, which are quantified by proper performance metrics. The fast response characteristics of the wind turbines allow for tracking even the faster automatic regulation signal (RegD from PJM). However, one of the significant challenges associated with providing such type of active power reference tracking on the wind farm scale is that different turbines have different responses and structural damage accumulation due to the local environmental conditions and the coupling due to wakes. The in-house developed, numerically efficient, wind farm simulation model “regfarm” is employed, allowing for a thorough analysis and revenue assessment under various operating regimes and weather conditions. Numerous time-domain simulations and historical pricing time series are used to quantify the expected revenue from market participation. Under the regulation market pay-for-performance compensation scheme, the simulated wind farm earned a lower revenue when compared to maximizing energy production. Depending on the configuration, the wind farm experiences between a 2.14% and a 2.38% decrease in revenue when providing 10% of the estimated available power to the regulation market. The wind farm is operated as both damage-ignorant and damage-aware, with no significant comparative loss in revenue when the damage distribution is considered.

Bifunctional electrolyte additive enabling long cycle life of vanadium-based cathode aqueous zinc ion batteries

Aqueous zinc ion batteries have received extensive attention due to their many advantages, but they still face problems such as dendrite growth and interface reaction of Zn anode and collapse of vanadium-based cathode structure. Here, a bifunctional electrolyte additive Methionine (MET) is proposed, which exhibits a unique role in inducing uniform deposition of zinc anode and inhibiting the failure of vanadium-based cathode materials. MET affects the solvated structure of the electrolyte to inhibit water activity and reduce HER and other related parasitic reactions. At the same time, it regulates the flux of Zn2+, improves the deposition kinetics of Zn2+ on the zinc anode side, and induces the preferential growth of the Zn (1 0 1) crystal plane to promote ordered Zn deposition. In particular, MET can in-situ generate a CEI containing such as ZnF2 on the surface of the vanadium-based cathode to inhibit the failure of the vanadium-based cathode, while adjusting the surface electronic state and Zn2+ diffusion behavior, and reducing the structural damage of the vanadium-based cathode caused by the Zn2+ intercalation process by inducing a strengthened surface pseudocapacitive reaction. Compared with the bare electrolyte, the capacity retention rate of the K2V8O21||Zn full-cell with OTF-M50 electrolyte increased from 10.2 % to 99.8 % after 800 cycles at a low current density of 1 A/g. Therefore, MET exhibits considerable application prospects as a bifunctional additive that can improve the stability of vanadium-based cathode and promote the stable deposition of zinc anode.

Tempol mitigates inflammation, oxidative stress, and histopathological alterations of cadmium-induced parotid gland injury in rats

Cadmium (Cd) is a potent environmental pollutant that causes functional and structural damage to the salivary glands. Tempol (TEM) has powerful antioxidant activity that can potentially preserve organ function. Aims: This study was designed to investigate the protective effects of TEM on Cd-induced toxicity in rat parotid salivary glands. Materials and methods: Twenty-four adult Wistar male rats were randomly assigned to four equal groups: control, TEM (27.5 g/100 ml), Cd (0.6 g/100 ml), and TEM plus Cd (at the same doses). All treatments were dissolved in distilled water and administered subcutaneously four times a week for four weeks. Parotid gland tissues were isolated and subjected to molecular and histo-biochemical assessments. Key findings: TEM exerted a prophylactic effect against Cd-induced toxicity in the parotid glands by controlling inflammation through the downregulation of toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor kappa B/ interleukin-1 beta mRNA expression, upregulation of aquaporin-5 mRNA expression, improvement of the oxidant/antioxidant status in the parotid gland, mitigation of endoplasmic reticulum stress, and repair of the associated histological and ultrastructural abnormalities. Significance: TEM protects against Cd-induced toxicity in the parotid glands of rats, attributable at least in part to its anti-inflammatory and antioxidant properties, as well as its ability to inhibit ER stress and facilitate glandular repair. However, the protective effects of TEM did not reach the levels observed in the control group. TEM could be a promising clinical candidate for protecting the salivary glands, particularly in high-risk groups such as workers exposed to Cd and cigarette smokers.

Machine Learning for Predicting Prehurricane Structural Damage

Machine Learning for Predicting Prehurricane Structural Damage

A refined nonlinear theoretical model for mechanical analysis of tunnels subjected to strike-slip faulting with multiple fault planes

During strike-slip fault dislocation, multiple fault planes are commonly observed. The resulting permanent ground deformation can lead to profound structural damage to tunnels. However, existing analytical models do not consider multiple fault planes. Instead, they concentrate the entire fault displacement onto a single fault plane for analysis, thereby giving rise to notable errors in the calculated results. To address this issue, a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations. The analytical model considers the number of fault planes, nonlinear soil‒tunnel interactions, geometric nonlinearity, and fault zone width, leading to a significant improvement in its range of applicability and calculation accuracy. The results of the analytical model are in agreement, both qualitatively and quantitatively, with the model test and numerical results. Then, based on the proposed theoretical model, a sensitivity analysis of parameters was conducted, focusing on the variables such as the number of fault planes, fault plane distance (d), fault displacement ratio (η), burial depth (C), crossing angle (β), tunnel diameter (D), fault zone width (Wf), and strike-slip fault displacement (Δfs). The results show that the peak shear force (Vmax), bending moment (Mmax), and axial force (Nmax) decrease with increasing d. The Vmax of the tunnel is found at the fault plane with the largest fault displacement. C, D, and Δfs contribute to the increases in Vmax, Mmax, and Nmax. Additionally, increasing the number of fault planes reduces Vmax and Mmax, whereas the variation in Nmax remains minimal.

Damage features and mechanism of prestressed hollow square piles subjected to non-contact underwater explosion

Critical hydraulic structures are increasingly vulnerable to underwater explosion attacks, with the supporting piles being prime targets for terrorist activities. This study investigates the damage effects and mechanisms of prestressed concrete hollow square (PCHS) piles under non-contact underwater explosions. A series of underwater explosion experiments was conducted on four PCHS piles. The dynamic response of PCHS piles throughout the underwater explosion process was simulated using a coupled fluid-solid numerical model. The mechanisms of dynamic damage to the PCHS piles were elucidated through an integrated analysis of both experimental and numerical results. The research indicates that the damage characteristics of PCHS piles include longitudinal and oblique cracks on the lateral surfaces, transverse cracks on the rear side, and localized fragmentation of concrete. Three primary damage modes have been identified: bending failure(L¯c= 0.59 m/kg1/3), combined bending-shear failure(L¯c= 0.36 m/kg1/3), and punching failure(L¯c= 0.24 m/kg1/3). The local and global responses induced by shock waves are the primary causes of structural damage. Furthermore, as the stand-off distance decreases, the impact of explosive bubbles increases the magnitude of the overall response. A comparative analysis also examined the impact of prestress and axial load on the damage behavior of hollow square piles.

A prospective randomized-controlled non-blinded comparative study of the JAK inhibitor (baricitinib) with TNF-α inhibitors and conventional DMARDs in a sample of Egyptian rheumatoid arthritis patients.

To evaluate the efficacy of baricitinib compared to TNF-α Inhibitors and conventional DMARDs (cDMARDs) in patients with RA. Our study included 334 RA patients classified into 3 groups: the first receiving baricitinib, the second receiving TNF-α Inhibitors, and the third receiving cDMARDs. Patients were evaluated at baseline, week 12, and week 24 using TJC, SJC, VAS, DAS28, CDAI, and HAQ-DI. Larsen score was measured at baseline and 24weeks. The response to therapy was assessed at weeks 12 and 24 using ACR 20, ACR 50, and ACR 70 response criteria. Emerging treatment side effects were monitored. Patients receiving baricitinib showed significant improvement regarding all outcome measures at weeks 12 and 24. In addition, baricitinib was comparable to TNF Inhibitors in all outcome measures except the ACR 70 at week 12, which was higher in the baricitinib group. Furthermore, baricitinib group showed significantly better outcome measures and response to therapy in comparison to cDMARDs group. The most common side effects in the baricitinib group were infection, GIT, and CVS complications. The most common side effects in the TNF inhibitors group were infection and skin complications. The cDMARDs had the least side effects, mostly GIT complications. Baricitinib is an effective drug for treating RA refractory to cDMARDs, improving disease activity measures and functional status and reducing the progression of structural joint damage. It has a comparable efficacy and safety profile to TNF Inhibitors. Multicenter studies are recommended to support our results. Key Points • Baricitinib is an effective therapeutic choice for rheumatoid arthritis refractory to cDMARDs. • Patients treated with baricitinib showed improvement in all outcome measures and functional status. • Bricitinib delayed the progression of radiographic joint damage more effectively than cDMARDs. • The efficacy and safety of baricitinib for treating rheumatoid arthritis is comparable to that of TNF inhibitors.

Quantitative characterisation of debris cloud-induced pitting damage in AL-Whipple shields of spacecraft using infrared thermography

ABSTRACT Quantitatively evaluating the debris cloud-induced pitting damage in the AL-Whipple structure of spacecraft, is still a challenge, let alone microstructural plastic deformation usually accompanied by geometric cratering defects, which may decrease material stress-carrying capacity and structural life. With this motivation, a dedicated modelling technique is proposed to gain an insight into various modalities (i.e., geometric and plastic defects) of pitting damage-induced thermal modulation for infrared inspection. Then, a sequence of infrared images is obtained and analysed using the gap smoothing algorithm and naive Bayes classification methods. On this basis, a quantitative characterization framework is proposed to characterize the damage modalities and their morphologies. This method is validated using a 3D numerical model which contains pitting damage acquired from the real-world structure. Modality classification and morphology evaluation results are well consistent with the artificial defects, in terms of the modality, diameter, and depth. Then they‘re experimentally corroborated, in which the severity and distribution of pitting damage are precisely characterized, in terms of the crater number and morphologies, as well as the size of plastic regions around these craters, which are consistent with the actual observations. This work proposes a non-destructive strategy for pitting damage evaluation, which is engineering-friendly.

Assessment of dynamic responses and impact resistance of corrugated plate-reinforced concrete tunnels under irregular rockfall scenarios.

This article presents a composite tunnel rockfall protection structure (CPRC) employing galvanized corrugated steel plates as the inner formwork for reinforced concrete structures. It addresses the threats posed by frequent rockfall disasters in mountainous regions with complex geology. The research investigates impact damage from various rockfall shapes through numerical simulations and experiments on five representative forms, comparing traditional reinforced concrete structures RC with CPRC. The study highlights both structures' dynamic responses and damage characteristics across different impact scenarios, introducing the Residual Resistance Index RRI as a measure of post-impact safety performance. Results show that the numerical simulations align with laboratory tests, with discrepancies within 10%, validating the simulation method's accuracy in predicting impact resistance. Following impacts, both structures primarily displayed brittle concrete damage; however, the CPRC structure demonstrated a 79.46% reduction in concrete damage and an 86.31% decrease in reinforcement damage. The energy-dissipating properties of the corrugated plates significantly lowered rockfall penetration depth and impact energy transfer ratio, with an RRI exceeding 0.88 post-event. Additionally, the study reveals varying damage effects from different rockfall shapes, further supporting the CPRC structure's superior impact resistance and its effectiveness in preventing secondary disasters in tunnel engineering within mountainous terrains.

Performance Evaluation of RC Structures using Next- Generation Performance-Based Seismic Assessment Procedures

Seismic forces have wreaked havoc on buildings around the world, resulting in both property damage and human deaths. Reinforced concrete structures under cyclic loading cannot be predicted using current methods, according to relevant design codes. Code-based seismic design procedures have been replaced by performance-based design procedures (PBSD). PBSD describes a building's overall performance by taking into account its structural and non-structural performance categories. Immediate occupancy, life safety, and collapse prevention are the three types of damage that can be encountered in a construction site. They are ranked based on the amount of damage, downtime, and casualties they inflict. Although these procedures can detect damage, they are unable to assign a numerical value to the seriousness of the damage. The use of damage indices, which are based on structural and response-based parameters, has been proposed by many researchers in the past. The objective of current research is an attempt to summarise all of these efforts and identify grey areas for further investigation. Numerical approaches to integrate structural damages with various PBSD performance levels have been proposed.

The 1912 Seismic Swarm in Guadalajara, Mexico: An Example of Intense and Unusual Seismicity in the Trans-Mexican Volcanic Belt

Abstract The residents of the Guadalajara, Mexico metropolitan area awakened on 8 May 1912 to a strong earthquake. In the next two months, ∼1500 shocks followed this first event. Two additional clusters of microearthquakes occurred in July and September. Although no significant structural damage was reported, several churches, public buildings, and private dwellings in the cities of Guadalajara and Zapopan suffered damage. Based on the macroseismic data, the intensity of the larger earthquakes was modified Mercalli intensity (MMI) VI–VII. The area that strongly felt the earthquakes and where the damage was concentrated is contained within a radius of ∼5 km. We assume that the swarm took place within this circle. Based on the relations of MMI versus peak ground acceleration (PGA), it is estimated that the PGA during the swarm was ∼190 gals. The magnitude of the largest earthquakes in the swarm was initially estimated as Mw 5.7, using a published PGA-to-Mw relation. However, this relation was based on earthquakes located 20 km away from downtown Guadalajara. Considering that the distance of the swarm from the city was ∼5 km, the magnitude of the largest events in the swarm was recalibrated as Mw 4.7. A second estimate of the magnitude was based on ground-motion models to calculate the PGA resulting from an earthquake located 5 km away, at a depth of 1 km. The resulting magnitude is Mw 5.3 ± 0.5. Thus, we suggest that the largest earthquakes of the swarm had an approximate magnitude of Mw 5.0. The location of the swarm suggests the presence of active faults underlying the metropolitan area of Guadalajara, where no seismicity has been recorded. This should be carefully considered to assess the seismic hazard of this important city of over 5 million people.

N-Acetyl Cysteine and Zinc Sulfate Attenuates Acute Crude Oil-Induced Oxidative Stress and Testicular Structural Damage in Male Wistar Rats

Introduction: Crude oil toxicity is caused by the production of reactive oxygen species (ROS), leading to oxidative stress and tissue damage. Both natural and synthetic antioxidants have shown potential in reducing the impact of this stress. This study evaluated the protective effects of N-Acetyl Cysteine (NAC) and Zinc Sulfate (ZnSO4) in alleviating testicular cytoarchitectural damage and oxidative stress in male Wistar rats after short-term exposure to Bonny light crude oil (BLCO) Materials and Methods: Fifty male Wistar rats (180–200g) were divided into ten groups of five. Group I (control) received distilled water, and Group II (negative control) was given BLCO (600mg/kg). Groups III and IV were administered NAC at doses of 100mg/kg and 200mg/kg, respectively. Groups V and VI received BLCO (600mg/kg) along with 100mg/kg and 200mg/kg NAC. Groups VII and VIII were treated with ZnSO4 at doses of 0.5mg/kg and 1mg/kg, respectively, while Groups IX and X were given BLCO (600mg/kg) combined with 0.5mg/kg and 1mg/kg ZnSO4. All treatments were administered orally via an orogastric cannula for three weeks. Testicular tissue was assessed by using histopathological examinations. Also, tissue malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) and total antioxidant capacity (TAC) were evaluated by using the ELISA technique. Results: Exposure to BLCO resulted in a significant increase in MDA and GSH levels and a significant decrease in SOD, CAT and TAC levels in BLO-exposed animals compared to control (P<0.05) which were mitigated by co-treatment with NAC and ZnSO₄. Histological analysis of the testes from rats exposed to BLCO revealed notable alterations in testicular morphology, including interstitial exudate, and atrophic and deteriorated seminiferous tubules which indicate testicular degeneration. However, this was improved on supplementation with NAC and ZnSO₄. Conclusion: This study demonstrates that BLCO-exposed rats experienced toxicity affecting both testicular antioxidants and testicular structure. Our findings suggest that NAC and ZnSO4 protected and improved testicular function in BLCO-exposed rats by enhancing testicular antioxidant levels and cytoarchitecture.

A constitutive model based on energy density for power-law variable thickness plates and its application

Variable thickness plates are relatively common structure in large-scale transportation equipment such as aerospace and ships. Due to their high running speed and large structural dimensions, such structures are usually induced high-frequency severe vibrations, which likely lead to structural damage. Therefore, it is crucial to accurately predict the high-frequency dynamic response characteristics during the structural design phase. The energy finite element method (EFEM) is a powerful tool for predicting high-frequency dynamic response. But, in recent EFEM for variable thickness plates, an approximate method (AEFEM) using a large number of constant thickness plate elements to approximate variable thickness plates is used. Due to that AEFEM is based on the constitutive equation for constant thickness plate, it will be imprecise and time-consuming. Aiming at power-law variable thickness plates, the constitutive equation based on energy density is derived and the finite element discrete scheme of the constitutive equation was studied. In this way, the precise new EFEM (NEFEM) for variable thickness plates was established. In addition, the dynamic response of a variable thickness plate was predicted by NEFEM presented and finite element method (FEM) respectively. The results are consistent. It is shown that the constitutive model presented is reliable and time-saving. Comparison of the results from AEFEM, the NEFEM can get more accurate results with fewer elements. The NEFEM based on the constitutive model presented can be used to predict precisely the high-frequency dynamic response for power-law variable thickness plates.

Monitoring a mass timber—BRB braced mass timber frame under cyclic loading via acoustic emission

This article focuses on the acoustic emission (AE) monitoring of a new type of mass timber buckling restrained brace (T-BRB), consisting of a wood casing made of mass plywood panel and a steel core embedded in the casing, for improving seismic resilience of mass timber structures. The casing secures the steel core through a series of bolts. To investigate the failure mechanisms of T-BRBs, two cyclic loading tests are conducted on a mass timber frame braced by T-BRBs with and without carbon fiber-reinforced polymer wraps, and an AE system is deployed for structural health monitoring (SHM). Multiple AE signatures are analyzed to infer the yielding point and failure modes of the T-BRB. AE features, including AE hit rate and cumulative energy, can successfully identify the ultimate structural failures. Results from AE hits and measured area of rectified signal envelope (MARSE) per quarter cycle suggest that the first significant feature values correspond to the cycle when the embedded steel core yielded. The b-value analysis demonstrates a general decreasing trend through the loading process and can characterize the evolution of structural damages. By evaluating both the strain energy and AE energy to reflect damage severity, the sentry function can identify the load cycle of steel core yielding and ultimate structural failure. As the first work applying AE monitoring on structural experiments of T-BRB, this research provides general guidances for SHM of T-BRB braced mass timber structures.

Test and simulation of high temperature resistant polyamide composite with single lap single bolt connection

The advancement of next-generation aerospace vehicles has presented new requirements and challenges for ensuring the structural integrity of aircraft components in extreme environments. Consequently, the utilization of high temperature resistant polyamide composite materials has become pivotal in the manufacturing of aerospace vehicle parts that operate under high temperatures (250 °C). As a critical connection technology for these materials, the mechanical behavior of bolted connection structures under high temperatures requires further investigation. In this paper, a combination of experimental and numerical simulation is used to investigate the load carrying capacity and failure mechanism of T700/BMP316 composite bolted joints at room temperature and 250 °C. The experimental results show that the ultimate load carrying capacity of the structure at 250 °C is only 13.1 % lower than that of the room temperature environment, indicating that the temperature softening effect of such composites is not significant. Scanning electron microscope (SEM) and computed tomography (CT) results indicate that the structural damage modes were the crushing of the hole edge fibers and matrix due to the extrusion by the bolts, as well as the interlaminar delamination damage. Temperature effects were taken into account for the composite principal structure and finite element modeling was performed using a combination of Pinho criterion and Cohesive model. Numerical simulations allow accurate prediction of the load-displacement response and damage pattern throughout the damage evolution phase. The high temperature test results and the developed finite element model involved in this study can support the design of new-generation aerospace vehicles.

Similarity analysis to enhance Transfer Learning for Damage Detection

Abstract One significant challenge in machine learning for Structural Health Monitoring (SHM) is reusing previously trained classifiers. A classifier might be suitable for one situation but not for another. Transfer learning techniques try to overcome this difficulty. In SHM, it is common to use the modal parameters as features; however, they are highly influenced by boundary conditions, geometry, and the level of structural damage. This work proposes an approach that performs a similarity analysis to select features before applying transfer learning, aiming at improving classification and damage detection. The reasoning is that a higher similarity leads to a more efficient transfer of learning and, consequently, a better classification. Transfer learning is conducted via the domain adaptation technique known as Transfer Component Analysis (TCA), and cases with low similarity are compared to those with high similarity. Two datasets are analyzed. The first consists of a beam under different boundary conditions, and data is generated through numerical simulations. The second derives from an experimental setup of bolted joints with loosening damage. The proposed strategy, which uses a cosine-type similarity, is shown to improve the transfer learning classification.

The Impact of Chemokine-Like Receptor 1 Gene Knockout on Lipopolysaccharide-Induced Epididymo-Orchitis in Mice.

This comprehensive study delved into the pivotal function of chemokine-like receptor 1 (CMKLR1) in lipopolysaccharide (LPS)-triggered epididymo-orchitis in mice. Upon LPS exposure, wild-type (WT) mice exhibited marked elevations in serum pro-inflammatory markers, including G-CSF, IL-6, and RANTES, along with heightened levels of TNF-α and IL-6 in testicular and epididymal tissues, which accompanied by pronounced structural damage within the testicular tissue and a concurrent decline in serum testosterone, estradiol (E2) levels, and testicular steroid synthetase expression. Remarkably, Cmklr1 gene ablation intensified the pro-inflammatory response in the serum (especially IFN-γ), testes, and epididymis of epididymo-orchitis models. Furthermore, Cmklr1 deficiency uniquely induced structural alterations within the epididymis, which is absent in the WT model. This genetic manipulation also exacerbated the decline in serum testosterone and E2 levels and testicular steroid synthase activity. While chemerin levels were significantly diminished in WT epididymo-orchitis models, Cmklr1 knockout had no discernible effect on chemerin expression in the model. In addition, a noteworthy observation was the elevation of the serum low density lipoprotein/high density lipoprotein (LDL/HDL) ratio in Cmklr1-deficient mice. Collectively, these findings underscore that the lack of chemerin/CMKLR1 signaling axis could potentially worsen the symptoms during LPS-induced epididymo-orchitis, highlighting its potential as a therapeutic target in related pathologies.

Seismic Performance of the Bridge Piers Reinforced with PP-ECC in the Plastic Hinge Region

Ductility deficiency in reinforced concrete (RC) piers is a substantial factor contributing to earthquake damage in bridge structures. In this study, the conventional concrete in the potential plastic hinge area was substituted with polypropylene fiber-reinforced engineered cementitious composite (PP-ECC), thereby leveraging its high ductility characteristics to explore the seismic performance of RC piers strengthened by PP-ECC. A finite element model was established to discuss the reinforced height, axial compression ratio, longitudinal reinforcement ratio and stirrup ratio on the hysteresis performance by referring to a published paper with a 1/5 scale test specimen. Based on the results of the parameter analysis, an ideal set of configuration parameters was proposed. Subsequently, a full-size simplified mechanical model was established with ideal reinforcement parameters. Time-history and pushover analysis were utilized to test the seismic response. The study indicates that the two analytical methods were largely consistent. The improvement in the displacement and shear force of the strengthened pier gradually decreased with the increase in acceleration amplitude. Time-history analysis reveals a decrease in the enhancement of displacement from 82.26% to 17.98% and a reduction at the bottom reaction from 12.2% to 1.5%. Under the pushover analysis method, the retrofitting level of the top displacement decreased from 77.22% to 11.53%, whereas the improvement level of the bottom shear decreased from 9.62% to 3.69%. These results provide a theoretical basis and reference standard for the application of PP-ECC.

Colchicine as a therapeutic option for the treatment of pulmonary arterial hypertension (PAH) in a rat model

Abstract Introduction Pulmonary arterial hypertension (PAH) is a cardiovascular disease that is characterized by severe structural and functional damages, resulting from the obstructive remodeling of the pulmonary vasculature and consequent right ventricular pressure overload. The current therapy mainly focuses on the pulmonary vascular system, with uncertain efficacy. Therefore, it is crucial to explore new therapeutic approaches. The mechanism of colchicine is complex and not-fully understood, but it has been proven to exert cardiopulmonary protective effects. Methods PAH induction was carried out in 8-week-old male WKY rats with a single subcutaneous injection of 60 mg/kg monocrotaline. Monocrotaline, a pyrrolizidine alkaloid, is metabolized in liver and induces inflammatory processes, which can cause PAH in rats. Starting from day 14 after MCT injection, the animals received three times a week intraperitoneal colchicine treatment at a dose of 0.5 mg/kg for two weeks. Echocardiographic examinations were performed during the study. At the end of the study, besides histological examination of the right ventricles and lungs [arterial wall thickness (WT%) and area (WA%)], the expression and phosphorylation levels of the proteins involved in cardiac remodeling were evaluated using Western blot. We assessed the pyruvate dehydrogenase (PDH) enzyme activity in the heart, which plays an important role in energy metabolism. We also examined the production of cytokines and chemokines in the right ventricle. Results The VW/BW ratio in the colchicine-treated group was significantly reduced compared to the MCT group (p<0.01). Echocardiographic parameters, EF% and E/e' ratio – characterizing the left ventricular function – did not differ considerably between the groups during the treatment. The TAPSE and PAT values characterizing right ventricular function improved in the MCT+C group (p<0.05). Collagen deposition and TGFβ level were significantly reduced by colchicine (p<0.05) in PAH animals. In the MCT+C group, the vascular remodeling (WT% and WA%) significantly decreased compared to the MCT group (p<0.01). The expression of α-SMA in vessel walls was most pronounced in the MCT group (p<0.01), which was significantly reduced by colchicine treatment. The phosphorylation of prosurvival signaling factors (ERK1/2, Akt1, GSK3β) was significantly increased in the MCT+C group (p<0.01) compared to the MCT group. In the right ventricle, PDH enzyme activity increased in the MCT+C group compared to the MCT group (p<0.01). According to cytokine array, cytokines involved in mediating fibrosis and inflammatory processes (TIMP-1, VEGF, L-selectin, CXCL7) showed increased secretion in the MCT group, which was moderately attenuated by colchicine treatment. Conclusion Colchicine treatment reduced the extent of fibrosis and inflammation, improved the structure of the pulmonary vasculature, and enhanced right ventricular function and energy supply.