Local Damage Research Articles

Abstract PR011: Efferocytic macrophage promotes pancreatic cancer liver metastasis

Abstract Pancreatic ductal adenocarcinoma (PDAC) presents a major therapeutic challenge due to its aggressive metastatic behavior. In the liver metastasis microenvironment of PDAC, macrophages are key drivers of tumor progression. Targeting these pro-tumorigenic macrophages requires a deep understanding of the various macrophage populations and the factors influencing their phenotypes. Our study has revealed a distinct subset of macrophages with a pro-tumorigenic phenotype that emerges early in PDAC liver metastasis. We found that the establishment of hepatic metastases triggers local tissue damage, which, through efferocytosis, reprograms macrophages into an immunosuppressive state, thereby facilitating metastasis. Inhibiting efferocytosis pharmacologically prevented the conversion of macrophages, enhanced CD8+ T cell responses, and reduced liver metastasis. These results highlight the role of macrophages in tissue repair processes that promote liver metastasis in PDAC and suggest potential therapeutic targets to hinder its progression. Citation Format: Yuliana Astuti, Meirion Raymant, Valeria Quaranta, Kim Clarke, Maidinaimu Abudula, Olivia Smith, Gaia Bellomo, Vatshala Chandran-Gorner, Craig Nourse, Christopher Halloran, Paula Ghaneh, Daniel Palmer, Robert Jones, Fiona Campbell, Jeffrey Pollard, Jennifer Morton, Ainhoa Mielgo, Michael Schmid. Efferocytic macrophage promotes pancreatic cancer liver metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr PR011.

Earliest location of glaucomatous retinal nerve fibre layer damage is determined by intact baseline RNFL thickness profile

Background/aimsTo identify whether an intact retinal nerve fibre layer (RNFL) thickness profile could determine the location of the earliest RNFL defect in glaucoma.MethodsRetrospective longitudinal cohort study of patients with initial...

An Alternative Finite Element Formulation to Predict Ductile Fracture in Highly Deformable Materials

Abstract An alternative finite element formulation to predict ductile damage and fracture in highly deformable materials is presented. For this purpose, a finite-strain elastoplastic model based on the Gurson–Tvergaard–Needleman (GTN) formulation is employed, in which the level of damage is described by the void volume fraction (or porosity). The model accounts for large strains, associative plasticity, and isotropic hardening, as well as void nucleation, coalescence, and material failure. To avoid severe damage localization, a nonlocal enrichment is adopted, resulting in a mixed finite element whose degrees-of-freedom are the current positions and nonlocal porosity at the nodes. In this work, 2D triangular elements of linear-order and plane-stress conditions are used. Two systems of equations have to be solved: the global variables system, involving the degrees-of-freedom; and the internal variables system, including the damage and plastic variables. To this end, a new numerical strategy has been developed, in which the change in material stiffness due to the evolution of internal variables is embedded in the consistent tangent operator regarding the global system. The performance of the proposed formulation is assessed by three numerical examples involving large elastoplastic strains and ductile fracture. Results confirm that the present formulation is capable of reproducing fracture initiation and evolution, as well as necking instability. Convergence analysis is also performed to evaluate the effect of mesh refinement on the mechanical response. In addition, it is demonstrated that the nonlocal parameter alleviates damage localization, providing smoother porosity fields.

Research and Evaluation of a New Structural Damage Identification Method Based on a Refined Genetic Algorithm

In order to solve the problem of structural damage location and degree identification, the weighted mean of vectors algorithm (INFO), a high-performance optimization algorithm, was first introduced to identify structural damage. By comparison with the refined genetic algorithm (RGA), the accuracy and advantages of INFO are analyzed and evaluated. An objective function is constructed by combining the dynamic response transfer ratio without modal analysis. The INFO and RGA algorithms are used to optimize the objective function for damage identification. The simulation results verify the effectiveness of the three damage identification methods. The results show that the identification effect of the INFO algorithm can reach nearly 100% without noise influence, and the anti-noise ability is the strongest. Among the three algorithms, the damage identification accuracy of the INFO algorithm is the highest, followed by the RGA algorithm and the GA algorithm.

Cannula Implantation Reduces the Severity of the Beta Amyloid Effect on Peroxidized Lipids and Glutathione Levels in the Brain of BALB/c Mice

Sporadic Alzheimer’s disease (sAD) is the most common of neurodegenerative disorders. The lack of effective therapy indicates that the mechanisms of sAD development remain poorly understood. To investigate this pathology in animals, intracerebroventricular injection of β-amyloid peptide (Aβ) using a Hamilton syringe, either during stereotactic surgery or through a pre-implanted cannula, is used. In this study, we analyzed the effect of chronic cannula implantation on the severity of Aβ effects at the behavioral, histological, and biochemical levels. The results showed that the local damage to neural tissue caused by cannulation has no bearing on the effect of Aβ on animal behavior and the microglial parameters of the unilateral hippocampus two weeks after the Aβ administration. However, cannula implantation fundamentally modifies some biochemical markers of the oxidative stress that occurs in the brain tissue in response to Aβ administration. Thus, the presence of a cannula reduces the severity of the Aβ impact on the levels of peroxidized lipids and glutathione two- and 10-fold, respectively. It is important to note that the detected changes are chronic and systemic. This is known because the homogenate of the entire contralateral (in relation to the cannula implantation site) hemisphere was analyzed, and the analysis was performed two weeks after implantation. At the same time, cannulation does not affect the rate of reactive oxygen species production. The obtained data indicate that chronic implantation of a cannula into the brain of experimental animals fundamentally distorts some parameters of oxidative stress in the neural tissue, which are widely used to assess the severity of experimental Alzheimer’s-type diseases.

Three-Dimensional Reconstruction and Damage Localization of Bridge Undersides Based on Close-Range Photography Using UAV

Abstract Damage inspection on the undersides of bridges is an important and challenging part of routine bridge inspections. A method for 3D reconstruction and damage localization of bridge undersides based on close-range photography by UAV and stereo vision combined with deep learning algorithms is proposed, the specific contributions include: (1) proposing a close-range photography method for acquiring high-resolution images from multiple perspectives of the bridge underside by UAVs, serving as the data source for damage analysis; (2) applying a deep learning-assisted segmentation method to optimize the multi-view geometry-based 3D reconstruction method, improving the efficiency of three-dimensional reconstruction, and defining the projection direction from the 3D reconstruction results to obtain ultra-high-resolution panoramic images of the bridge underside; (3) addressing the issue of detecting minor damages in large panoramic images by using a slice-assisted reasoning module and a lightweight convolutional YOLO v8 network to identify exposed steel bars corroded due to concrete damage in the panoramic images, and defining a coordinate system to localize the damages on the bridge underside. The proposed method was applied to damage detection and localization on the underside of a 160m span main span of an in-service concrete bridge. The results demonstrate that the proposed method can quickly and accurately identify exposed steel bar corrosion on the bridge underside and output reports, proving the practicality of the proposed method.

An in-situ investigation of microstructure neighborhood effects on hydrogen-induced dislocation activity

The interactions between hydrogen and crystallographic defects are the key to understanding hydrogen induced localized plasticity or damage mechanisms. However, unraveling such interactions based on the resulting mechanical effects alone can be challenging, due to the spectrum of various effects hydrogen can create in a given microstructure. Pre-deformation or post-mortem characterization of hydrogen segregation has similar limitations, as they can only provide snapshots of these complex processes with challenging spatial and temporal scales. To tackle this, we design in situ experiments that combine electron channeling contrast imaging (ECCI), electron backscattered diffraction (EBSD), and desorption spectroscopy, to investigate hydrogen defect interactions, under no external loading. We show that the inhomogeneous hydrogen distribution within microstructures can cause long-range (>200 nm) dislocation rearrangements. Interpretation of these results as manifestations of boundary-segregation induced stress suggests that microstructural characteristics on either side of the boundary should also play an important role. We provide quantitative assessments of these microstructure neighborhood effects and discuss additional contributions from hydrogen-induced changes in stacking fault energy and elastic modulus.

Detection of Cut-Out in Aluminum Plate Using Ultrasonic Guided Waves: A Finite Element Analysis

<div>Aluminum alloys serve a critical role in the aerospace industry, accounting for a significant amount of commercial aircraft weight. Despite the growing use of composite materials, aluminum remains important in airframe construction due to its lightweight, cost-effectiveness, and high strength potential. Structural integrity is critical in modern engineering, necessitating early diagnosis and localization of damage. To detect the flaws, cracks, and cut-out in the structures, structural health monitoring (SHM) systems are essential, with non-destructive testing (NDT) methodologies playing critical roles. Among these technologies, ultrasonic guided wave testing (UGWT) has gained popularity because of its capacity to propagate over long distances and detect subsurface faults. This article investigates the use of UGWs to identify cut-outs in aluminum plates. The numerical investigation has been carried out using commercially available finite element software Abaqus. The ultrasonic lamb waves are generated through the load. The results obtained in pristine and defected 2D aluminum plate has been compared with proper selection of actuation and sensing points. Further by changing the location of actuation and sensing points the shift of damage scattering components has been observed. After identification of reflected wave mode, the location of the cut-out can be predicted accurately.</div>

Navigating the Complexities of Radiation Injuries: Therapeutic Principles and Reconstructive Strategies

Radiation injuries, particularly those resulting from therapeutic or accidental exposure, present complex challenges for medical management. These injuries can manifest localized skin damage or extend to deeper tissues, presenting as various clinical entities that require treatment strategies, ranging from conservative management to complex surgical interventions. Radiation treatment constitutes a fundamental component of neoplastic management, with nearly two out of three oncological instances undergoing it as an element of their therapeutic strategy. The therapeutic approach to radiation injury consists of expanding prophylactic measures while maintaining the efficacy of treatment, such as conservative treatment or local debridement followed by reconstruction. The armamentarium of reconstructive methods available for plastic surgeons, from secondary healing to free tissue transfer, can be successfully applied to radiation injuries. However, the unique pathophysiological changes induced by radiation necessitate a careful and specialized approach for their application, considering the altered tissue characteristics and healing dynamics. The therapeutic strategy is guided by both the severity and progression of the injury, with the primary aim of restoring functionality and aesthetic aspects while simultaneously minimizing the risk of complications. This paper explores the various conditions encompassed by the term “radiation injury,” reviews both non-surgical and surgical therapeutic strategies for managing these injuries, and highlights the unique challenges associated with treating irradiated tissues within specific oncological contexts.

EFFECTIVE DOSAGE OF CORROSION INHIBITORS FOR OILFIELD EQUIPMENT PROTECTION FROM LOCALIZED CARBON DIOXIDE CORROSION

The article presents the results of laboratory tests of the industrial corrosion inhibitor VITERASOYUZ-2000 of the BP-2 brand (class of imidazolines) used in the oil and gas industry. In 2021, one of the vertically integrated companies purchased 20 thousand tons of this reagent, which is 10 % of the total purchased volume. The volume of corrosion inhibitors purchased by the company annually (~ 200 thousand t) is 97 % a product of domestic manufacturers. The main line of inhibitors purchased in 2021 is represented by the following brands: Sonkor (> 40 thousand t), Azol (~ 40 thousand t), Kormaster (> 30 thousand t), UnoKem (~ 30 thousand t), VITERASOYUZ (~ 20 thousand t), Scimol (> 10 thousand t), ETK (~ 10 thousand t), others (~ 20 thousand t). These reagents were used to inhibit carbon dioxide, hydrogen sulfide and mixed corrosion of oilfield equipment.In order to evaluate the effectiveness of inhibitors in suppressing local carbon dioxide corrosion and determine their effective dosage laboratory studies were performed using a specially developed authors’ technique. A distinctive feature of the technique is the modeling of an essential feature of corrosion processes occurring in real oilfield systems in the presence of carbon dioxide – a high rate of local corrosion exceeding the corrosion rate by 2–9 times. The standard environment and conditions of laboratory experiments used in laboratory tests make it possible to reproduce local corrosion damage visible and measured using a needle micrometer (> 0.01 mm) on corrosion control samples by the weight method. It is shown that the protective effect of the corrosion inhibitor VITERASOYUZ-2000 of the BP-2 brand in relation to local corrosion is achieved at a dosage of 100–150 mg/dm3.The practical significance of the research is shown by a retrospective analysis of data from weight (gravimetric) corrosion monitoring during industrial testing of corrosion inhibitors, which confirm that the use of «traditional» dosages of 15–40 mg/dm3 (based on the total volume of liquid = oil + water) with a high protective effect against corrosion consumption («general corrosion») do not provide a protective effect against local corrosion. It is noted that in some cases, corrosion inhibitors, due to reducing corrosion consumption, can not help only reduce the rate of local corrosion, but, on the contrary, stimulate its development. The target of the tests is to increase the reliability of pipeline operation and environmental safety while reducing the increase in accidents and the number of failures.

Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests

Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.

Baseline-free assisted lamb wave-based damage detection in CFRP composites using graph convolutional networks and Transformer models

Carbon fiber-reinforced polymer (CFRP) composites are widely used in aerospace but are susceptible to damage, threatening structural safety. Thus, developing an effective structural health monitoring system is essential. This study presents CFRP-former, a novel deep learning framework that detects damage in CFRP composites by constructing spatio-temporal representation graphs of Lamb waves (LWs). The CFRP-former comprises three key modules: graph convolutional neural network (GCNN), a multi-layer perceptron (MLP), and a Transformer Encoder. The GCNN models the topological relationships between LW nodes and sensors. The MLP reduces data dimensionality while preserving key information for subsequent analysis. Meanwhile, the Transformer Encoder, employing multi-head attention mechanisms, captures global time-series patterns in the LW signals. Additionally, the CFRP-former framework includes a parallel module that separately predicts both the size and location of damage. Experiments using only four sensors show that CFRP-former achieves high accuracy in detecting and quantifying damage, with robustness confirmed through ablation tests.

Efficacy of modal curvature damage detection in various pre-damage data assumptions and modal identification techniques

The efficacy of modal curvature approach for damage localization is discussed in the paper in the context of input data. Three modal identification methods, i.e., Eigensystem Realization Algorithm (ERA), Natural Excitation Technique with ERA (NExT-ERA) and Covariance Driven Stochastic Subspace Identification (SSI-Cov), and four methods of determining baseline data, i.e., real measurement of the undamaged state, analytical function, Finite Element (FE) model and approximation of current experimental mode shape, are considered. Practical conclusions are formulated based on analysis of two cases. The first is a laboratory beam with a notch and the second is a stonemasonry historic lighthouse with modern restoration in its upper part. The analysis shows that NExT-ERA and SSI-Cov in combination with approximation of current mode shape provide high efficacy in damage localization alongside relatively straightforward determination of baseline data. It proves that the construction of advanced FE models of a structure can be replaced with a much simpler method of baseline data acquisition. Furthermore, the research shows the structural mode shapes identified with ERA may not always indicate the presence of damage.

Research on combined damage characteristics of underwater armor-piercing and explosion based on supercavitating projectile

Recent studies of supercavitating projectiles primarily focus on the formation and evolution of the cavity, as well as its underwater ballistic characteristics, while neglecting the terminal damage effects. Little attention has been given to exploring the combined damage effects of armor-piercing-explosion supercavitating projectiles (APESP). Therefore, this study comparatively analyzes the response processes and failure modes of an underwater aluminum alloy cylindrical shell target under the action of three different types of loads: armor piercing, explosion, and combined armor-piercing and explosion. This study investigates the underwater combined damage mechanisms of the APESP, clarifies each damage phase under the combined effect, discusses the advantages of damage resulting from the combined armor-piercing and explosion effect based on the target responses and damage modes, and explores the reasons for dissipation of explosion energy. The results show that: the APESP combines localized point damage characteristics of armor piercing with overall surface damage features of underwater explosion. Depending on load stages and target responses, the target response process under the action of the APESP can be divided into the hydrodynamic ram phase, penetration phase, shock wave phase, stable vibration phase, and bubble pulsation phase. The entire physical system can be abstracted as a low-frequency series spring system (equivalent to bubble pulsation frequency) with high-frequency external energy input, based on the energy relationship of the medium and the structure. The concept of the 'blower effect' is proposed based on target behavior during the stable vibration phase. Following the application of different loads, the plastic deformation of the target in a stable state is ranked as: underwater explosion > combined armor-piercing and explosion > underwater armor piercing. Supercavity, shell casing and penetration hole will cause the dissipation of explosion energy.

Bridge Damage Localization Through Response Reconstruction with Multiple BP-ANNs Under Vehicular Loading

Bridge Damage Localization Through Response Reconstruction with Multiple BP-ANNs Under Vehicular Loading

Research on Damage Detection of Dual-Rotor Synchronous Excitation Mine Screen Beams Based on Strain Mode Difference Vibration Mode Analysis

The frame beam structure of the mine screen, subjected to various excitations, is a critical component of mining machinery. Its stress is intricate, the operational environment is severe, and damage can lead to catastrophic failures resulting in machinery destruction and fatalities. Based on the characterization of the vibration response of mine screen frame beams with varying degrees of damage at the same location and with the same degree of damage but at different locations, this paper develops a method of strain modal difference vibration pattern analysis and damage feature extraction for the detection of structural damage in beams. This method is based on the sensitivity of the sudden change in vibration strain modal difference to small deformations. This method solves the problem of using the conventional structural finite element analysis or experimental modal analysis methods to obtain the displacement mode, intrinsic frequency, and other characteristics, which make it difficult to effectively identify the actual engineering, with the damage conditions of the damage state and damage location of the mine screen frame beam problems. The feasibility and validity of the engineering application of the concept are demonstrated through instances.

A novel damage localization method of Circular Phased Array using Minimum Variance Distortionless Response Beamforming with Autocorrelation Matrix Diagonal Loading

Damage localization methods based on Acoustic Emission (AE) can be classified into time-based and waveform-based. However, the former requires a large number of sensors while the latter is limited to 2D plane localization. In order to address the challenge of achieving more accurate 3D localization using a reduced number of sensors, this paper proposes a Circular Phased Array using Minimum Variance Distortionless Response (MVDR) Beamforming with Autocorrelation Matrix Diagonal Loading (AMDL) method. Firstly, a sparse circular array is utilized to form multiple beamforming for coherent shear wave signals, decomposing the original 3D localization problem into Direction Of Arrival (DOA) estimation. Secondly, azimuth angle, elevation angle and autocorrelation matrix diagonal loading methods are introduced, working in conjunction with the MVDR beamforming algorithm. Finally, spatial integration is performed through matrix decomposition to solve geometric overdetermined equations. The effectiveness of the proposed method is validated through numerical simulations and experimental verifications under various damage conditions. Results indicate that estimation errors for azimuth and elevation angles are both less than 2 %, while 3D damage source localization errors remain within a range of less than 3 %. This proposed method extends beamforming technology from 2D plane localization to 3D localization, significantly reducing the complexity of sensor arrangement and lowering the cost of structural health monitoring systems by utilizing a small number of sensors.

Thermal ablation of soft tissue by a single shock wave sonication of discrete foci within the given volume

New protocols have been developed for shockwave irradiation of soft tissue volumes using trajectories uniformly filled within the given shape by discrete foci, while pulsed millisecond sonication immediately formed a single ablation. The influence of the initial peak power with the same time-average power, the interfocus distance and the geometry of the external contour of the trajectory on the shape, volume and ablation rate was analyzed. The most advantageous is the saturation mode using a trajectory with an interfocus step 1.5 times greater than the transverse size of a single lesion. To obtain volumes of thermal ablation on the order of cubic centimeters, layer-by-layer sonication protocols are proposed, which allow to 2.5 times greater thermal ablation rate compared with protocols used in clinical practice. The advantage of the proposed shockwave protocols is the possibility of obtaining localized and predictable thermal damage without accompanying MRI monitoring.

Computer vision-based substructure isolation method for localized damage identification

In recent years, vision-based structural damage identification techniques have garnered significant attention due to their simplicity and cost-effectiveness. Nevertheless, dynamic response-based vision methods face challenges related to the limitations of the field of view (FOV), i.e., the extent of the FOV is often sacrificed in order to ensure sufficient monitoring accuracy, which reduces the amount of data available for structural health monitoring (SHM). This study presents a solution to this problem by employing the substructure isolation method (SIM), which focuses on local vibrations of the structure and enables local damage identification by isolating the area of interest. Additionally, a method combining kernelized correlation filter (KCF) with sub-pixel template matching is used to extract vibration information recorded by visual sensor. This strategy balances both the efficiency and accuracy of displacement extraction. In numerical simulations, the performance of the SIM based on acceleration response and displacement response is compared, demonstrating the potential compatibility of visual sensors with the SIM. Finally, the effectiveness of the proposed vision-based local damage identification method is validated through vibration testing of a shear frame model.

Fragmentation behavior and velocity formula for secondary fragments from RC slabs during contact explosions

The failure process of reinforced concrete (RC) slabs under contact explosion is dominated by localized damages, accompanied by numerous flying fragments. These concrete fragments pose a significant threat to personnel and equipment, as well as causing dynamic deformation and failure of the retrofitting materials used to restrain the fragments. The behavior of concrete fragmentation during explosions has been seldom studied experimentally, and few fragment velocity formulas exist that incorporate multiple factors. In this paper, the fragmentation process is recorded using two high-speed cameras, revealing that concrete fragmentation during explosions exhibits notable zoning characteristics, with the maximum velocity observed at the center of the fragment cloud’s front. To predict this maximum velocity, a model is derived from dimensional analysis. Utilizing this model, velocity prediction formulas are proposed and validated by 29 contact explosion tests. The formulas consider the explosive-rebar position, slab thickness, explosive mass and explosive shape, and are further improved by considering the concrete cover. The results indicate that, when the slab is not breached, the deceleration of rebar on fragments is weak. However, once the slab is breached, this deceleration becomes increasingly significant as the defined scaled thickness (TS) decreases. In the limiting case, the fragment velocity when the charge is located above the rebar is 0.636 times that of when the charge avoids the rebar. Fragments when the charge avoids the rebar, should be regarded as the most unfavorable case in secondary fragment hazards assessment and structural design.