Stages Of Damage Research Articles

Changes in Global Longitudinal Strain after TAVI: Additional Prognostic Value over Cardiac Damage in Patients with Severe Aortic Stenosis.

Background: Previous studies demonstrated the prognostic value of baseline cardiac damage staging as well as left ventricular global longitudinal strain (LVGLS) in patients undergoing transcatheter aortic valve implantation (TAVI). The aim of the present study was to evaluate the changes in cardiac damage stage and LVGLS after TAVI and to investigate their prognostic values when integrated into the follow-up assessment. Methods: Patients with severe aortic stenosis undergoing TAVI were hierarchically classified into cardiac damage stages based on echocardiographic criteria before TAVI and at a 6-month follow-up. At the same time, LVGLS was measured. The staging system included stage 0 = no signs of cardiac damage; stage 1 = LV damage; stage 2 = mitral or left atrial damage; stage 3 = pulmonary vasculature or tricuspid damage; and stage 4 = right ventricular damage. The primary endpoint was all-cause mortality. Results: A total of 620 patients were included. At follow-up, LVGLS significantly improved, and the improvement was similar among each baseline cardiac damage stage. Follow-up LVGLS values were divided into quintiles, and each quintile was integrated into the cardiac damage staging, leading to a reclassification of 308 (50%) patients. At the time of a median follow-up at 48 (IQR 31-71) months starting from the 6-month follow-up after TAVI, 262 (38%) patients had died. A multivariable Cox regression model showed that LVGLS-integrated cardiac damage staging at follow-up had an incremental prognostic value over the baseline assessment (HR per 1-stage increase 1.384; 95% CI 1.152-1.663; p < 0.001). Conclusions: The integration of LVGLS with conventional echocardiographic parameters of cardiac damage at a 6-month follow-up after TAVI can improve patient risk-stratification.

Renin-Angiotensin System Inhibition and Cardiac Damage in Patients Undergoing Transcatheter Aortic Valve Replacement

BackgroundThe optimal medical treatment strategy after transcatheter aortic valve replacement (TAVR) has not been established, and might be affected by the extent of extravalvular cardiac damage. We aimed to investigate the prognostic association of renin-angiotensin system (RAS) inhibitors in TAVR patients stratified according to the extent of extravalvular cardiac damage. MethodsIn a prospective TAVR registry, patients were retrospectively evaluated for baseline cardiac damage and classified into 5 stages of cardiac damage (0-4) according to established criteria. Clinical outcomes at 1 year were compared according to RAS inhibitor prescription at discharge. ResultsAmong 2247 eligible patients who underwent TAVR between August 2007 and June 2021, 1634 (72.7%) were prescribed RAS inhibitors at discharge. Eighty-three patients (3.7%) were classified as stage 0, 276 (12.3%) as stage 1, 889 (39.6%) as stage 2, 489 (21.8%) as stage 3, and 510 (22.7%) as stage 4. RAS inhibitor prescription after TAVR was associated with a reduced risk of 1-year mortality (adjusted hazard ratio [HRadjusted], 0.59; 95% confidence interval [CI], 0.45-0.77). The protective association was accentuated among patients with cardiac stages 3 and 4 (HRadjusted, 0.54 [95% CI, 0.32-0.92]; and HRadjusted, 0.58 [95% CI, 0.36-0.92], respectively), but not statistically significant in for those with stage 2 (HRadjusted, 0.70; 95% CI, 0.43-1.14). ConclusionsIn patients who underwent TAVR, we found a strong association of RAS inhibitor prescription and improved clinical outcome in the overall population, and there were no signs of heterogeneity across stages of cardiac damage. Clinical Trial RegistrationNCT01368250.

Implementation and validation of robot-enabled embedded sensors for structural health monitoring

In the past decades, structural health monitoring (SHM) has matured into a viable supplement to regular inspections, allowing to execute repair and maintenance work at early stages of structural damage, thus resulting in relatively low rehabilitation costs. With the advent of wireless technologies and advancements in information and communication technologies, civil infrastructure has been increasingly instrumented with wireless sensor nodes to record, analyze, and communicate structural data relevant to SHM. However, in harsh environments, wireless sensor nodes may be damaged and fail to operate. A promising alternative to wireless sensor nodes is to embed sensors directly into concrete. In this paper, a sensor system for embedment into concrete is proposed, able to self-assess the structural data recorded from the concrete. Moreover, the data and information provided by the sensors are collected by robotic systems via RFID data transfer in an attempt to reduce the amount of human interaction and to overcome the limitations with respect to communication range and power supply. In laboratory experiments, the sensor systems are embedded into a concrete structural element, validating the capabilities of the sensors to record and to analyze the structural data. Furthermore, as will be shown in the paper, power will be supplied on-demand by legged robots that are deployed to collect the data and information, which is provided by the sensors for persistent storage. In summary, this study corroborates that the embedded sensors represent a crucial step towards intelligent, self-assessing concrete.

Finite element analysis and simplified envelope curve model for RC shear key under earthquake-tsunami actions

Coastal bridges are vulnerable to the compounded effects of earthquakes and subsequent tsunamis. Their limited lateral restraints can result in critical risks such as the deck unseating or overturning. To this end, reinforced concrete (RC) shear keys are often integrated to enhance the superstructure resilience. While previous studies have investigated their seismic performance, their effects under seismic-tsunami actions remains relatively unexplored yet. This study employed finite element (FE) analysis to examine shear key properties under such conditions, with emphasis on hysteretic curves, concrete damage, and strain evolution. The FE model was developed in accordance with precedent tests, and the modeling results were also compared with tests. A simplified envelope curve model was developed using both geometry and rebar configuration, with various damage states included to reckon their seismic damages after initial earthquakes. The proposed model was validated and aligned well with test results. Further, a framework was proposed to determine the envelope curve for bridges at different damage stages. This study aims to provide insights into the seismic-tsunami analysis on coastal bridges by considering their varying properties under seismic and tsunami actions.

Mechanical Properties and Energy Damage Evolution Mechanism of Basalt Fiber-Modified Tailing Sand Cementation and Filling Body Mechanics

In order to investigate the mechanical properties of basalt fiber-doped tailing sand cemented filler and the evolution of energy damage, a uniaxial compression test was carried out on the basalt fiber-doped tailing sand cemented filler specimens to analyze the energy dissipation characteristics, and the damage constitutive equations with different basalt fiber contents were established based on damage mechanics. The results show that with the increase of fiber doping and fiber length, the uniaxial compressive strength and ductility of the filling body show a trend of increasing and then decreasing; the optimal value of fiber doping is 0.6%, and the optimal value of fiber length is 9 mm; the total strain energy, elastic strain energy and dissipation energy of basalt fiber-modified tailing sand cemented filling body at peak stress show a trend of increasing and then decreasing, and the energy dissipation energy of the filling body shows a trend of increasing and then decreasing. The energy dissipation energy shows a trend of increasing and then decreasing, and the energy dissipation energy shows a trend of increasing and then decreasing. The total strain energy, elastic strain energy, and dissipation energy at the peak stress show a trend of decreasing after increasing with the fiber doping and fiber length, and the energy damage evolution process can be divided into four stages: no damage stage, stable damage development stage, accelerated damage growth stage, and damage destruction; in addition, the existing damage constitutive model of the fiber-filled body was optimized, and the damage correction factor was introduced to obtain the damage constitutive model of the filled body with different fiber contents, and finally, after the verification of experimental and theoretical models, it was found that the two stress–strain curves coincided well. Finally, after the test and theoretical model verification, it is found that the stress–strain curves of the two are in good agreement, which indicates that the established theoretical model has a certain reference value for engineering practice, and at the same time, it has certain limitations.

Aortic Stenosis and the Evolution of Cardiac Damage after Transcatheter Aortic Valve Replacement.

Background/Objectives: Severe aortic stenosis (AS) is the most frequent valvular heart disease. Models for stratifying cardiac damage associated with aortic stenosis have been developed to predict outcomes following valve replacement. However, evidence regarding morphological and functional evolution, as well as potential changes in the degree of cardiac damage, is limited. We aim to provide information on the evolution of cardiac morphology and the function of patients undergoing transcatheter aortic valve replacement (TAVR) who have been classified using a cardiac damage staging system. Methods: In total, 496 patients were included in the analysis, and were classified into four stages based on the extent of cardiac damage as follows: Stage 0, no cardiac damage: left ventricle global longitudinal strain (LV-GLS) < -17%; right ventricular-arterial coupling (RVAc) ≥ 0.35), and absence of significant mitral regurgitation (MR). Stage 1, left-sided subclinical damage: LV-GLS ≥ -17%. Stage 2, left-sided damage: significant MR. Stage 3, right-sided damage: RVAc < 0.35. Results: The mean age was 82.1 ± 5.9 years, and 53.0% were female. In total, 24.5% of patients met the criteria for Stage 0, and Stage 1 included 42.8% of patients, Stage 2 included 16.5%, and Stage 3 comprised 16.2% of patients. Mortality was 8.4% for stage 0, 17.4% for stage 1, 25.6% for stage 2, and 28.6% for stage 3 patients (p = 0.004). Diabetes mellitus (DM) (p = 0.047) and chronic kidney disease (CKD) (p = 0.024) were the only clinical predictors of no change or worsening in the stage of cardiac damage. Regarding echocardiographic variables, concomitant tricuspid, and mitral regurgitation, ≥ 2 were both significantly associated with no change or worsening, also (p < 0.001). Conclusions: Cardiac damage that is secondary to severe aortic stenosis has morphological and functional repercussions that, even after valve replacement, persist and might worsen the prognosis.

Residual strength and failure mechanism of CF/PPS composites with delamination damage

AbstractDelamination is one form of damage in composite laminates. The effects of delamination damage locations (thickness direction of laminates) on the residual compressive strength and failure mechanism of carbon fiber/polyphenylene sulfide (CF/PPS) composites are studied by damage morphology, full‐field strain and finite element simulation. The closer the delamination is to the center of the composite, the lower the residual compressive strength. The failure mode of composites is dominated by 0° fiber fracture, which is divided into bulging, delamination propagation, and fracture. The delamination locations significantly affect the first two stages.Highlights Constructing delamination damage in composites by interlayer preset defects. Simulation and damage analysis to reveal the mechanism of compression failure. The relationship between delamination depth and damage stage is revealed.

Laminated Steel Fiber-Reinforced Concrete Hingeless Arch: Research on Damage Evolution Laws

In the context of reinforced concrete (RC) arch bridges, while the incorporation of full sections of steel fibers can enhance the bridge’s toughness, cracking resilience, and bearing capacity, achieving an optimal balance between structural performance and economic viability in this manner remains challenging. This article introduces a novel computational approach—the distributed steel fiber concrete (LSFRC) arch—which considers the spatial distribution of damage in RC arches. The static performance of SFRC elements and LSFRC beams was compared and analyzed using the concrete plastic damage model (CDP) in ABAQUS software. This study validated the rationality of the model and investigated the impact of varying steel fiber volume ratios and steel fiber layer heights on the damage evolution of LSFRC arches. The results of this study demonstrate that the cracking load and bearing capacity of an RC arch can be effectively enhanced through the addition of steel fibers to a local area under static loading. Furthermore, the deflection and damage to the arch waist and arch roof can be significantly reduced. Furthermore, the incorporation of steel fibers at an increased volume rate and at a greater height within the doped section can effectively slow the rate of damage evolution within the section. This results in the inhibition of crack extensions and in an improvement in the ductility and reliability of the damage stage. The LSFRC arches offer superior economic and practical advantages over their full cross-section doped steel fiber (FRC) counterparts. This study offers novel insights and methodological guidance for the design and implementation of concrete arch bridges.

Implementation of a predictive strategy in the diagnosis of inflammatory periodontal diseases

Relevance. The diagnosis of periodontal diseases, considering their severity, prevalence, progression, and staging, can be achieved by determining the levels of biomarkers or molecular imaging biomarkers in biofluids such as crevicular or sulcular fluid (GCF or GSF), saliva, and oral fluid. GCF is currently regarded as one of the diagnostically significant biological fluids for assessing the condition of periodontal tissues, not only in clinical diagnostic laboratories but also in dental offices. The implementation of sensitive, highly accurate, non-invasive, and specific methods for rapid GCF diagnosis, based on the qualitative analysis of biomarkers of cytokine imbalance, immunological disorders, changes in non-specific defence factors, and biophysical indicators, will allow for an objective assessment of the condition of periodontal tissues.Purpose. To improve the efficiency of periodontitis prevention using a developed mathematical model for personalized prediction of the course of inflammatory periodontal diseases based on the investigated biomarkers in GCF.Material and methods. The study included 101 patients: Group I consisted of 22 patients diagnosed with K05.10 (gingivitis), Group II included 31 patients diagnosed with K05.31 (mild periodontitis), and Group III comprised 18 patients diagnosed with K05.31 (moderate periodontitis). The comparison group consisted of 30 individuals with clinically healthy periodontium. All subjects underwent clinical and instrumental examination, determination of periodontal indices, GCF collection, and quantitative analysis of immune regulatory mediators (IL-1β, IL-6, TNF-α, IL-8, MCP-1, IL-17, VEGF, IL-1RA).Results. The study of immune regulatory mediators confirmed the significance of increased levels of pro- and anti-inflammatory cytokines/chemokines, as well as the reduction of the anti-inflammatory biomarker IL-1RA in GCF at the early stages of inflammatory changes in periodontal tissues. This is accompanied by the appearance of signs indicating the destruction of the dentogingival junction. Using logistic regression and training a multiclass classifier based on the support vector machine method, a model was developed to predict the risk of dentogingival junction loss in patients, potentially leading to periodontitis.Conclusion. The results of logistic regression modelling and training a multiclass classifier based on the support vector machine method demonstrate that in diagnosing the initial stages of periodontal tissue damage with the loss of the dentogingival junction (DGJ), the most effective approach is the comprehensive use of inflammatory process biomarkers and the development of multi-marker algorithms based on a computer program.

Shear Performance and Damage Characterization of Prefabricated Basalt Fiber Reactive Powder Concrete Capping Beam Formwork Structure

Basalt Fiber Reactive Powder Concrete (BFRPC) semi-prefabricated composite capping beam structures can effectively improve the shortcomings of ordinary concrete capping beams' construction difficulties and insufficient bearing capacity. In this study, with the objective of analyzing the shear damage and damage characteristics of a prefabricated BFRPC capping beam formwork, structural damage tests under different levels of loading were carried out to obtain the mechanical parameters of key nodes. Acoustic emission (AE) and Digital Image Correlation (DIC) techniques were used to acoustically and visually characterize the formwork damage. The research results showed that the damage stage of the capping beam formwork was divided, and an early damage warning method was proposed based on the acoustic parameters. Using the DIC technique to identify the crack width evolution pattern during the shear process, it was found that the cracks expanded steadily as the load increased. Combining the experimental and simulation results as well as the Subdivision Superposition Theory, a half-open stirrup strength discount factor β was introduced and suggested to take a value of 0.79. The formula for calculating the shear capacity of BFRPC capping beam formwork is proposed to provide a theoretical basis for its application in prefabricated assembled structures.

Cardiac Damage in Degenerative Mitral Regurgitation Treated With Transcatheter Mitral Edge-to-Edge Repair.

The extent of cardiac damage and its association with clinical outcomes in patients undergoing transcatheter edge-to-edge repair (TEER) for degenerative mitral regurgitation remains unclear. This study was aimed to investigate cardiac damage in patients with degenerative mitral regurgitation treated with TEER and its association with outcomes. We analyzed patients with degenerative mitral regurgitation treated with TEER in the Optimized Catheter Valvular Intervention-Mitral registry, which is a prospective, multicenter observational data collection in Japan. The study subjects were classified according to the extent of cardiac damage at baseline: no extravalvular cardiac damage (stage 0), mild left ventricular or left atrial damage (stage 1), moderate left ventricular or left atrial damage (stage 2), or right heart damage (stage 3). Two-year mortality after TEER was compared using Kaplan-Meier analysis. Out of 579 study participants, 8 (1.4%) were classified as stage 0, 76 (13.1%) as stage 1, 319 (55.1%) as stage 2, and 176 (30.4%) as stage 3. Two-year survival was 100% in stage 0, 89.5% in stage 1, 78.9% in stage 2, and 75.3% in stage 3 (P=0.013). Compared with stage 0 to 1, stage 2 (hazard ratio, 3.34 [95% CI, 1.03-10.81]; P=0.044) and stage 3 (hazard ratio, 4.51 [95% CI, 1.37-14.85]; P=0.013) were associated with increased risk of 2-year mortality after TEER. Significant reductions in heart failure rehospitalization rate and New York Heart Association functional scale were observed following TEER (both, P<0.001), irrespective of the stage of cardiac damage. Advanced cardiac damage is associated with an increased risk of mortality in patients undergoing TEER for degenerative mitral regurgitation. URL: https://www.clinicaltrials.gov; Unique identifier: UMIN000023653.

Study on Numerical Simulation of Large-Diameter Borehole Pressure Relief in Deep High-Gas Soft Coal Seams.

The deep highly gassy soft coal seam has the characteristics of high ground stress, high gas pressure, and low permeability. In the process of coal roadway excavation, there are problems such as frequent gas concentration exceeding the limit and easy induction of gas dynamic disasters. To investigate the pressure relief and disaster reduction efficiency of large-diameter boreholes in a deep high-gas soft coal seam, the 8002 high-gas working face of the Wuyang coal mine was taken as the engineering background to study the deformation law of large-diameter boreholes in deep high-gas soft coal seams. A coupled damage-stress-seepage model for pressure relief of large-diameter boreholes in gas-bearing coal seams was constructed based on the Hoek-Brown criterion, the correlation between the damage area and the gas pressure distribution in the gas-bearing coal seam after the pressure relief of boreholes of different apertures was analyzed, and the pressure relief efficiency of different technical parameters "three flower holes" in the roadway head was determined. The law of stress transfer, gas migration, and energy release in the coal seam after pressure relief of a large-diameter borehole under different initial gas pressures was revealed, and the power function equations of the damage range and borehole diameter, maximum stress at the roadway head, and driving distance after pressure relief of a gas-bearing coal seam were determined. Results showed that under the confining pressure of the 8002 working face roadway in the Wuyang coal mine, the pressure relief effect of 250 mm aperture is better, the drilling plastic zone is "butterfly" or "X″-type distribution, and the plastic zone range is positively correlated with the aperture size. Under the arrangement of "three flower holes", the plastic zone is larger and the pressure relief effect is better when the hole spacing is 1.4 m. With the increase of initial gas pressure, the vertical stress above the borehole increases and the pressure relief efficiency decreases. According to the vertical stress distribution within 200 h of borehole pressure relief, the pressure relief process is divided into a coal damage and failure stage, stress balance stage, and hole collapse stability stage. The research results provide a theoretical basis for the prevention and control of coal rock gas dynamic disasters by large-diameter drilling in a deep high-gas soft coal seam.

Optimizing the Utilization of Steel Slag in Cement-Stabilized Base Layers: Insights from Freeze-Thaw and Fatigue Testing.

This paper presents a study on the mechanical properties of cement-stabilized steel-slag-based materials under freeze-thaw cycles for a highway project in Xinjiang. Using 3D scanning technology the specimen model conforming to the real steel slag shape was established. The objectives of the study are as follows: to explore the sensitivity between the macro- and micro-parameters of the specimen and to establish a non-linear regression equation; and to study the changes in mechanical properties of materials under freeze-thaw cycles, fatigue loading, and coupled freeze-thaw cycle-fatigue loading. The results show that there are three stages of compression damage of the specimen, namely, linear elasticity, peak plasticity, and post-peak decline. Maximum contact forces between cracks and particles occur mainly in the shear zone region within the specimen. The compression damage of the specimen is a mixed tensile-shear damage dominated by shear damage. When freeze-thaw cycles or fatigue loads are applied alone, the flexural strength and fatigue life of the specimens show a linear relationship of decline. The decrease in flexural modulus at low stress is divided into the following: a period of rapid decline, a relatively smooth period, and a period of fracture, with a tendency to change towards linear decay with increasing stress. In the case of freeze-thaw-fatigue coupling, the flexural modulus of the specimen decreases drastically by about 50% in the first 2 years, and then enters a period of steady decrease in flexural modulus in the 3rd-5th years.

Evolution of the damage precursor based on the felicity effect in shale

Damage precursors during hydraulic fracturing in shale gas reservoirs may be better understood if the deformation, failure, and acoustic emission (AE) characteristics under cyclic loading are known. Therefore, the purpose of this paper is to investigate the quantitative damage based on the Felicity effect under constant stress lower limit uniaxial cyclic loading-unloading rates (0.5, 1.0, 1.5, 2.0, and 2.5 kN/s). Variations in the b-value and the spatiotemporal evolution of cumulative AE were also used to observe how shale fractures formed. The findings reveal that during the unloading stage, there are many cumulative AE events when the stress level is low (≤1.50 kN/s) but that this number drops significantly when the stress level increases above (&gt;2.0 kN/s). The AE amplitude, AE counts, and cumulative AE energy of each cycle in a loading-unloading test show an increasing trend, but the rate increases in the last cycle. During the whole process of loading and unloading, the Kaiser effects were present in the 3rd cycle at stress levels (≤1.5 kN/s). Still, the Felicity effect appeared in the 2nd and 1st cycles during 2.0 and 2.5 kN/s cyclic loading. The Kaiser effect occurs in the linear elastic stage, while the Felicity effect occurs in the crack initiation and crack damage stage. Furthermore, the Felicity ratio (FR) variations during shale deformation and failure can be divided into four phases: (Phase I = 1.01 ≥ FR &gt; 0.89), (Phase II = 0.89 ≥ FR &gt; 0.48), (Phase III = 0.48 ≥ FR &gt; 0.23), and (Phase IV = FR ≤ 0.23). The b-value is relatively higher under the loading rate below (≤1.50 kN/s), indicating an increase in the number of small AE events. In contrast, the fact that the b-value is relatively smaller under the loading rate above (&gt;2.0 kN/s) indicates that, the number of large AE events increases the number of cracks and fractures. These findings provide important design references for damaged precursors during hydraulic fracturing in shale gas reservoirs.

Durability and Mechanical Properties of Nano-SiO2 and Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites Subjected to Saline Freeze-Thaw Cycles.

To investigate the effects of nano-SiO2 (NS) and polyvinyl alcohol (PVA) fibers on the durability and mechanical properties of cementitious composites subjected to saline freeze-thaw cycling, a series of PVA fiber-reinforced cementitious composite (PFRCC) specimens were prepared using various fiber contents, and a series of NS and PVA fiber-reinforced cementitious composite (NPFRCC) specimens were prepared using various combinations of NS and fiber contents. Durability and fracture toughness tests were subsequently conducted on the specimens after different numbers of saline freeze-thaw cycles. The results indicate that the degradation of material properties can be divided into slow and accelerated damage stages before/after 50 freeze-thaw cycles. The durability and fracture toughness of the specimen series tended to increase, then decrease with increasing NS and PVA contents, suggesting optimum levels. When the PVA fiber content was 0.5%, PFRCC specimens had the best durability after saline freeze-thaw cycles; when the NS and PVA fiber contents were 1.0% and 0.5%, respectively, NPFRCC specimens had the best durability and fracture properties, and the initiation toughness, destabilization toughness, and fracture energy after 100 saline freeze-thaw cycles were 120.69%, 160.02%, and 451.31%, respectively. The results of this study may guide future exploration of the durability and mechanical properties of concrete subjected to freeze-thaw action.

#2534 Classification of patients with acute kidney damage on the base of blood pressure value as a risk factor using a neural network

Abstract Background and Aims In acute kidney damage, the monitoring of hemodynamic status is best achieved by determining the blood pressure value. It is considered that the values of diastolic blood pressure in young and healthy people are constant from the aorta to the periphery, and the values of systolic and pulse pressure increase from the periphery to the aorta. The frequency of hypertension correlates with the presence of a cardiovascular precipitating risk factor in acute kidney injury, hypertension is also a modifying risk factor in the second and third stages of acute kidney injury, while the presence of hypotension on admission can be a clinical indicator of its cause. In patients with acute kidney damage and in patients with sepsis, the mechanism of autoregulation of mean arterial pressure, which is affected by stroke volume and heart rate, is not effective. The aim of the paper is to examine the classification of hospitalized patients with acute kidney injury based on blood pressure as a risk factor. Method The study included 86 patients over 18 years of age of both sexes (39 men 45.3% and 47 women 54.7%) with an average age of 66.85 ± 15.30 years who were diagnosed with acute kidney injury on admission to hospital treatment. Patients were divided into groups according to the stages of renal insufficiency. The study was designed as a cross-sectional comparative study. The assessment of the existence of acute kidney damage, as well as the determination of the stage of the disease, was based on the diagnostic criteria proposed by the K/DIGO expert group for acute kidney damage. The study did not include patients who had disease progression after acute kidney failure and were treated with dialysis for more than three months. Basic clinical, biochemical and hemodynamic parameters were determined in all subjects at the beginning of treatment, except for the analysis of nitrogen status, which was determined both before and at the end of treatment. During the formation of the neural network (pattern recognition Mat Lab), the parameters of systolic arterial pressure, diastolic arterial pressure normalized by min-max normalization to values from 0 to 1 were included. The data were randomly distributed into three categories: 80% for training, 10% for test, 10% for validation, which means that the parameters of 68 patients were used for training, 9 patients for validation and another 9 patients for the test. The number of input parameters is 33 to 39, while the number of output parameters is 2 in relation to treatment. Formed neural networks with different included blood pressure parameters, structures of 25 neurons in the hidden layer, with 55 and 15 epochs and with accuracy of 97.7% and 90.7% of patient classification. Results Our results show that 40.3% of patients in the third stage of acute kidney injury have hypertension. The lowest average values of systolic (108.44 ± 22.81 mmHg) and diastolic (65.56 ± 15.29 mmHg) blood pressure were experienced by patients in the first stage of acute kidney damage, and the lowest values of mean arterial pressure existed in the second stage of acute kidney damage (68.20 ± 44.96 mmHg) .Statistically significant risk factors for the development of the third stage of acute kidney damage in the multivariate analysis were patients older than 65 years, and mean arterial pressure values less than 65 mmHg. The confusion matrices showed that the classifiers adapted to the minimum and maximum values of systolic, diastolic and mean arterial blood pressure are well adapted and achieve satisfactory accuracy with 97.7% and 90.7%. Conclusion By comparing blood pressure parameters in hospitalized patients in relation to the stage of acute kidney damage, no statistically significant deviations were found. Univariate logistic regression analysis showed that age over 65 was a significant independent risk factor for stage three acute kidney injury, while the multivariate model showed that risk factors for the development of stage three acute kidney injury were patients same age and middle arterial blood pressure less than 65 mmHg. Satisfactory accuracy of formed neural networks when classifying patients during validation training and test was also demonstrated.

Uncovering the progressive failure process of primary coal-rock mass specimens: Insights from energy evolution, acoustic emission crack patterns, and visual characterization

The failure and instability of deep coal-rock mass structures, which are influenced by mining disturbances, are major contributors to disasters like rock bursts. This study involved conducting indoor experiments using uniaxial loading test and acoustic emission (AE) experiments on indigenous primary coal-rock mass (PCRM). We utilize chaotic bifurcation based on strain energy to characterize the progressive damage stages of PCRM, demonstrating the chaotic characteristics of energy evolution during the gradual destruction process. The degree of damage resulting from PCRM failure was evaluated by jointly applying P-wave velocity tomography and AE event localization. Additionally, the classification of crack patterns in PCRM was conducted using the RA-AF correlation analysis method. The segmentation boundaries of crack classification patterns were then redefined using the Gaussian mixture model (GMM) algorithm. The research findings indicate that the chaotic bifurcation model of strain energy classifies stress into four stages: the stable region (Ⅰ), the metastable region (Ⅱ), the bifurcation region (Ⅲ), and the chaotic region (Ⅳ). The presence of a low-velocity zone in P-waves may indicate crack accumulation and damage within the system. Additionally, areas with abnormal P-wave velocities exhibit numerous AE events. The crack classification patterns of the four stages undergo an evolution from predominantly tensile cracks to a mixture of tensile and shear cracks, and the GMM algorithm successfully identifies the optimal separation path for crack classification boundaries. We propose an adaptive kernel density estimation (AKDE) algorithm to quantify the spatial distribution of AE events, thus offering a visual representation of the damage patterns at various stages.

Comparative study of linear and nonlinear ultrasound applied to the detection of hydrogen damage in 7N01 aluminum alloy

7N01 aluminum alloy samples with different hydrogen damage degrees were prepared by electrochemical hydrogen charging technology. 7N01 aluminum alloy samples with different degrees of hydrogen damage were characterized by metallographic observation, hardness test and XRD test. The results show that the hydrogen content increases with the increase of hydrogen charging time. The surface of aluminum alloy is exfoliated and pits appear. The more severe the hydrogen damage, the greater the depth of pits. The microhardness of the 7N01 aluminum alloy decreases after hydrogen damage, which only occurs near the surface. After electrochemical hydrogen charging, AlH3 appears in the structure of 7N01 aluminum alloy, which is the result of increased hydrogen concentration. The ultrasonic echo signals of hydrogen damaged samples were obtained by a high frequency longitudinal probe ultrasonic detection device, and the results of linear and nonlinear ultrasonic detection were compared. Traditional linear ultrasonic detection parameters such as sound velocity and attenuation coefficient do not change significantly in the early stage of hydrogen damage, but increase significantly in the late stage of hydrogen damage. Due to the change of microstructure, the nonlinear coefficient increases approximately linearly in the early stage of hydrogen damage and decreases in the late stage of hydrogen damage. This study demonstrates the potential for combining linear and nonlinear ultrasonic measurements in hydrogen environment to more comprehensively study hydrogen damage.

Crack detection and damage evaluation of asymmetrical steel-reinforced concrete frame nodes using acoustic emission technology

ABSTRACT Detecting cracks in steel-reinforced concrete (SRC) frame nodes is crucial for ensuring structural safety. This study employs acoustic emission (AE) technology to monitor the growth of concrete structural defects in real time. The aim is to establish a sensitive assessment method based on AE parameters to accurately assess the damage stages of SRC frame nodes by considering the complex crack extension mechanism in SRC structures. An experimental study of the AE characteristics of SRC frame nodes under low-cycle loading was performed. The crack evolution process of SRC frame nodes was monitored and analysed using the AE parameters. The results showed that ringing count is the AE parameter more sensitive to the damage of the SRC frame node. The damage evaluation method was established based on the variation coefficient analysis of the AE parameters. Considering the sudden change in the growth rate of the damage index, the damage evolution process of the SRC frame nodes can be accurately divided into three stages: initial crack compaction, rapid crack expansion, and crack penetration. These stages are consistent with the mechanical properties of SRC frame nodes.

Prevalence and Associated Factors of Cataract, Cataract Surgery and Postoperative Outcome in an Old Population in Russia: The Ural Very Old Study

PurposeTo assess prevalence of cataract and cataract surgery in a very old population in Russia. DesignPopulation-based study. ParticipantsThe Ural Very Old Study included 1526 (81.1%) participants out of 1882 eligible individuals aged 85+ years. MethodsBased on anterior and posterior segment imaging, we assessed the prevalence of cataract, cataract surgery and other ocular disorders affecting best corrected visual acuity (BCVA). Main outcome measuresPrevalence of cataract and cataract surgery. ResultsThe study included 1163 (76.3%) individuals with lens information. Cataract surgery had been performed in 469 right eyes (41.0%;95%CI:38.1,43.9) (92.1% with posterior chamber IOL; 4.7% with multifocal IOL) and 479 left eyes (41.6%;95%CI:38.7,44.4) (92.7% with posterior chamber IOL; 4.2% with multifocal IOL). Among the 1163 study participants, 610 (52.5%) individuals had undergone cataract surgery in at least one eye. Higher prevalence of previous cataract surgery correlated (multivariable analysis) with lower IOP (OR:0.92;95%CI:0.88,0.95;P<0.001), glaucomatous optic nerve damage stage (OR:1.20;95%CI:1.05,1.36;P=0.006), and better visual acuity (OR:0.67;95%CI:0.51,0.89;P=0.005). Postoperative BCVA (mean:0.83±1.43logMAR) was reduced to moderate-to-severe vision impairment (MSVI) in 202 eyes (44.6%;95%CI:40.0,49.2) and to blindness in 53 eyes (11.7%;95%CI:8.7,14.7). Causes of postoperative MSVI were age-related macular degeneration (AMD) (34.2%), glaucoma (13.9%), and secondary cataract (5.4%). Causes for blindness were AMD (24.5%), glaucoma (18.9%), corneal opacifications (15.8%) and myopic macular degeneration (11.3%). YAG-laser capsulotomy had been performed in 6 (1.3%) out 469 right eyes after cataract surgery and in 12 (2.5%) out of 479 left eyes after cataract surgery. Prevalence of nuclear cataract and cortical cataract was 604/671 (90.0% in phakic eyes 51.9% in the whole study population) and 97.9% eyes (48.4% in total study population). Cataract caused bilateral MSVI and blindness in 28.2% (95%CI:25.6,30) and 2.9% (95%CI:1.9,3.9), respectively, of all study participants. ConclusionsDespite a relatively high prevalence of cataract surgery, this multiethnic cohort aged 85+ years from Russia showed a high prevalence of cataract-related MSVI and blindness, due to the old age of the participants. After cataract surgery, main causes for MSVI (prevalence:44.6%) and blindness (prevalence:11.7%) were AMD, glaucoma, corneal opacifications, and myopic macular degeneration. Almost all individuals aged 85+ years need cataract surgery, despite limited chance of postoperative good vision.