Rupture Time Research Articles

The long-term creep behavior and damage mechanism of RAFM steel for fusion reactors

The reduced-activation ferritic-martensitic (RAFM) steel serves as the structural material for the blanket of the International Thermonuclear Experimental Reactor (ITER) and future fusion reactors. In order to achieve a design lifetime of 2–3 years for the blanket in the fusion reactor, it is imperative to thoroughly understand the long-term (>20,000 h) creep behavior of RAFM steel. In this regard, the present study investigated the long-term creep damage mechanism of RAFM steel under creep periods greater than 20 000 h. The results indicated that the creep exponent decreases as the creep rupture time increases from several thousand hours to more than 20,000 h. The microstructure analysis revealed that dislocation slip was effectively pinned by the precipitates in the long-term creep process. Additionally, the M23C6 and Laves phase played a critical role in inhibiting interfacial slip and preventing lath coarsening. However, a few micron-scale M23C6 and Laves phases led to the formation of cavities in the boundary. These cavities subsequently polymerized and aggravated into cracks, ultimately becoming the primary mechanism for the long-term creep fracture.

Efektivitas Air Rebusan Daun Binahong Dengan Air Rebusan Daun Sirih Terhadap Penyembuhan Ruptur Perineum Pada Ibu Bersalin Di Puskesmas

Introduction: Perineal rupture is a birth canal tear that often occurs in the normal delivery process and is a health problem that must be treated immediately because it can cause infection so treatment needs to be carried out. The data from the Banjarsari Health Center report in 2021 showed that there were 35 cases of perineal rupture (72,91%) from 48 postpartum mothers. The purpose of the research is to find out the effectiveness of boiled water from binahong leaves with boiled water from betel leaves for healing perineal rupture in women giving birth at the Banjarsari Health Center Lebak Regency in 2022. Methods: The research method uses quasi-experiments with a posttest-only design with non-equivalent groups. The sample of this study was a spontaneous postpartum mother who experienced a perineal rupture of 30 people with a sampling technique using simple random sampling. Instruments use questionnaires. The Bivariate analysis uses the paired t-test and independent t-test. Results: The average healing time of perineal rupture given boiled water of binahong leaves is 5,87 (5 to 6 days) while that given boiled water of betel leaves is 7,93 (7 to 9 days). The results of statistical tests show that there is the effectiveness of binahong leaf boiled water with betel leaf boiled water against healing perineal rupture in maternity mothers at the Banjarsari Health Center Lebak Regency in 2022 (p = 0,006). Discussion: Giving boiled water to binahong leaves is faster and more effective in curing perineal rupture compared to giving betel leaf boiled water. It is hoped that postpartum mothers can use non-pharmacological methods using herbal complementary therapy for the treatment of perineal rupture namely by using binahong leaf boiled water or using betel leaf boiled water.

Prevention and Treatment of Epitheliopathy as a Result of Acute Inflammatory Diseases of the Ocular Surface

Acute inflammatory diseases of the ocular surface occur in case of epitheliopathy. As a result, most patients complain of discomfort and persistence of residual inflammation after the infection has been stopped.The purpose: to assess the degree of damage to the ocular surface as a result of bacterial conjunctivitis and keratitis, as well as the regenerative effect of dexpanthenol 5 % eye gel on the healing and restoration of the functional activity of the ocular surface epithelium.Methods. A non-randomized case-control study was performed in patients with a bacterial infection of the conjunctiva and cornea. Under supervision there were 23 patients (46 eyes) diagnosed with bacterial conjunctivitis and 31 patients (31 eyes) with bacterial keratitis. According to the study design, patients were divided into two groups. After stopping the acute process, dexpanthenol 5 % eye gel was prescribed. To control the effectiveness, the tear film rupture time, the degree of damage to the mucin coating and surface epithelial cells were evaluated. Diagnostic tests with vital dyes (fluorescein (FA) and lyssamine green (LG)) were performed before the appointment of the gel, then seven and thirty days after the appointment of the drug.Results. After the relief of bacterial inflammation, 86.9 % patients with conjunctivitis and in all cases of keratitis had complaints (unpleasant sensations and redness of the eyes, blurred vision). There was a decrease in tear break-up time (TBUT) test, a significant accumulation of dye in the conjunctiva in both study groups and a partial accumulation of FA in the cornea, more intense in keratitis. After 7 days Corneregel use, there was an increase in TBUT compared to the baseline level, with a further increase in this indicator after a 1 month, a decrease in the manifestation of conjunctival epitheliopathy and the degree of corneal staining.Conclusions. The appointment of dexpanthenol 5 % eye gel after stopping a bacterial infection helps to relieve discomfort, accelerates the restoration of regeneration of the epithelial cells of the ocular surface, and increases the strength of the tear film.

Poster 337: Impact of an ACL rupture on a professional soccer player’s career

Objectives: While advances in surgical technique have led to high levels of return to play in professional soccer players, little is known about their medium- and long-term career trajectory and performance. Methods: A retrospective review was performed of a consecutive series of primary ACL reconstructions in professional soccer players from the senior author’s practice, with a minimum of two-year follow-up. Clinical and performance measures were evaluated at 2- and 5-years post ACLR to determine pre- operative, operative and post-operative factors that affected player performance- measured by the level of league and number of minutes played. Results: 200 male, soccer players were identified who were playing professionally at the time of their primary ACLR. The average age at the time of their primary ACL reconstruction was 24.1±4.2 years. Additional injuries at the time of ACL rupture included 63 (32%) medial meniscus tears with 42 (67%) repaired, 134 (67%) lateral meniscus tears with 82 (62%) repaired, and 31 (16%) chondral lesions of grade 3 or higher. 194 (97%) athletes returned to play (RTP) at 10.7±3.9 months. Return to play was strictly defined as returning to a professional level. Eighteen (9%) athletes sustained a re-rupture at a median of 11.1 months (IQR 8.6-16.6 months) with 6 occurring pre-RTP and 12 post-RTP, while 52 (26%) sustained a contralateral ACL rupture during their soccer career. At 2 years, performance metrics showed that 59% of athletes were playing in the same or higher-level league, while 15% were in a lower-level league but had more game appearances and minutes played than pre-injury. By 5 years 34% of athletes were playing in the same or higher-level league and 26% were in a lower-level league but had more game appearances and minutes played. At 2 years, there were no significant predictors of performance when evaluating factors such as concomitant injuries, undergoing surgery after ACLR, or mechanism of injury. However, the presence of a grade 3 or 4 chondral lesion at the time of surgery significantly impacted both career length and performance with only 15% of athletes playing at the same or higher league at 5 years and these athletes were 3.5 times more likely to be playing at a lower league level or retired (p=.029). Meniscus repair lengthened the RTP timeline (11.6 months versus 9.8 months, p=.001), but no impact was seen at 5 years with league level or performance (all p>.05). No other injury characteristic predicted performance at 5 years post ACLR. Conclusions: While a high level of return to play, 97%, was achieved in professional soccer players following primary ACLR, their performance decreased with time. Performance metrics show 59% of athletes are at the same league level at 2 years and this decreases to 34% at 5 years post ACLR. Presence of a Grade 3 or 4 chondral lesion significantly decreased performance metrics, while a meniscus repair delayed RTP but did not impact performance metrics at 5 years post ACLR. [Table: see text]

Poster 297: Deep medial collateral ligament reconstruction of the knee restores rotational stability throughout full range of motion while contemporary MCL reconstruction only does in extension

Objectives: The past decade has taught the importance of identifying and treating the concomitant injuries that frequently occur at the time of ACL rupture. Failure to do so can result in increased stresses on the ACL graft and subsequently increased risk of failure. While the focus has largely been on the menisci and the anterolateral soft tissues, recent studies have highlighted high frequency at which injuries to the medial structures occur in previously presumed isolated ACL tears and the increased risk of poor outcomes when they are not addressed. Injuries to the medial ligament complex result in valgus and anteromedial rotatory instability (AMRI). Historic MCL reconstruction techniques have focused on the superficial MCL in an effort to restore valgus stability while frequently ignoring the importance of the deep MCL in controlling tibial external rotation. The recent recognition of the importance of the medial ligament complex has led to multiple studies revisiting medial sided anatomy and questioning contemporary MCL reconstruction techniques. The objective of this study is to assess and compare the ability of a contemporary medial collateral ligament (MCL) reconstruction and a deep MCL (dMCL) reconstruction to restore rotational and valgus stability to the knee. Methods: Six pairs fresh-frozen cadaveric knee specimens were included and with intact soft tissue, the distal femur and tibia were potted in PVC pipes to facilitate biomechanical testing using a customized multi-axial knee activity simulator. Four states were tested: 1) intact 2) after sectioning of the sMCL and dMCL, 3) contemporary MCL reconstruction as described by LaPrade et al, and 4) dMCL reconstruction. In each state, the knees were tested under four loading conditions at varying flexion angles (0°, 20°, 40°, 60° and 90°): 8 Nm valgus torque, 5 Nm tibial external rotation torque, 90N anterior drawer, and combined 90 N anterior drawer plus 5 Nm tibial external rotation torque. Results: Transection of the sMCL and dMCL resulted in increased laxity with the application of the valgus torque, external rotation torque, and combined anterior drawer plus external rotation at all flexion angles. dMCL reconstruction restored external rotation stability to intact levels (all p<0.05) throughout all degrees of flexion (Figure 1), yet dMCL reconstruction did not restore valgus stability at any flexion angle (Figure 2). Contemporary MCL reconstruction restored valgus and external rotation stability at 0° and 20° and valgus stability at 40° (p<0.01). In response to a combined anterior drawer plus tibial external rotation, the dMCL restored stability back to the intact level at 20° and improved stability between 40° and 90° flexion (Figures 3 and 4). In contrast, the contemporary MCL reconstruction did not restore stability at any degree of flexion (p>0.05). Conclusions: Deep MCL reconstruction restored rotational stability to the knee throughout range of motion but did not restore valgus stability. The contemporary MCL reconstruction restore stability only near full extension.

Simple Estimation of Creep Properties of Negative Electrode for Lithium-Ion Battery

The macroscopic creep properties of negative electrodes in lithium-ion batteries and their estimation methods have been investigated based on the microscopic structure of the electrode. Tensile and creep tests were conducted on a negative electrode consisting of carbon powder and polyvinylidene fluoride (PVDF) binder. The stress-strain curve, the time history of the tensile strain, and the creep rupture time were measured in these tests and estimated using the simple model proposed in this study. The proposed model approximates the alignment of carbon particles as body-centered cubic (bcc) or face-centered cubic (fcc). The external load on the model was supported by a PVDF binder located between carbon particles. The test results showed that PVDF binder mechanical properties affect the macroscopic mechanical properties of the negative electrode, including the creep properties. The stress-strain curve and time history of the tensile strain were located between the upper and lower limits of the proposed model. The tensile strength and creep rupture time agree with the lower limit of the proposed model.

Dependence of Mechanical Properties of Platinum-Rhodium Binary Alloys on Valence Electron Parameters

Dependence of mechanical properties of binary platinum-rhodium alloys on valence electron ratio (VER), number of valence electrons (ev) and average atomic number of the alloys (Z) are investigated. The alloys have a high number of valence electrons (9 ≤ ev ≤ 10) and a wide range of average atomic numbers (Z = 45–78). Clear correlations between VER of the alloys and their mechanical properties are found. By increasing the VER of the alloy from 0.13 to 0.20 following the increase of rhodium content in the composition, the hardness, elastic modulus and ultimate tensile strength (UTS) of the alloy increases. Creep rates of the selected alloys clearly decrease with increasing VER at high temperatures (1500–1700°C), while stress rupture time at different temperatures consistently increases because of higher rhodium content in the alloy solid solution chemistry. Dependence of mechanical properties on valence electron parameters is discussed with reference to the atomic bonding.

"Gloppiness" Phenomena and a Computer Vision Method to Quantify It.

In this study, we present a rapid, cost-effective Python-driven computer vision approach to quantify the prevalent "gloppiness" phenomenon observed in complex fluids and gels. We discovered that rheology measurements obtained from commercial shear rheometers do show some hints, but do not exhibit a strong correlation with the extent of "gloppiness". To measure the "gloppiness" level of laboratory-produced shower gel samples, we employed the rupture time of jetting flow and found a significant correlation with data gathered from the technical insight panelist team. While fully comprehending the "gloppiness" phenomenon remains a complex challenge, the Python-based computer vision technique utilizing jetting flow offers a promising, efficient, and affordable solution for assessing the degree of "gloppiness" for commercial liquid and gel products in the industry.

Latency Antibiotics in Preterm Prelabor Rupture of Membranes: A Comparison of Azithromycin Regimens.

Treatment with antibiotics at the time of preterm prelabor rupture of membranes (PPROM) has been shown to prolong pregnancy. Due to the recurrent shortage of erythromycin, azithromycin has been substituted in the traditional regimen; however, there are little data on optimal dosing. The objective of this study was to determine whether there is a difference in latency from onset of PPROM to delivery in patients who received a single dose of azithromycin compared with a 5-day course. This was a single-center, multisite, retrospective, IRB approved analysis of patients admitted with a diagnosis of PPROM. Patients were included if rupture occurred between 22 0/7 and 33 6/7 weeks of gestation and received either a single dose or a 5-day course of azithromycin along with a beta lactam. A total of 376 patients were reviewed with 296 patients included in the final analysis. There was no statistical difference in the primary outcome of latency days in patients who received the 5-day versus the single-dose course (4 vs 5 days, P = 0.641). There was a significantly higher rate of histologic chorioamnionitis in the single-dose course of azithromycin (46.4% vs 62.6%, P = 0.006). There was no difference in latency for patients who received a 5-day course of azithromycin versus a single dose for the treatment of PPROM. A higher rate of histologic chorioamnionitis was observed in those who received the single-day course. Prospective follow-up studies are needed to confirm these findings.

The effects of adherence to recommended antenatal services on adverse pregnancy outcomes in Northwest Ethiopia: multilevel and propensity score matching (PSM) modeling.

Adverse pregnancy outcomes are a personal and social crisis caused by easily preventable pregnancy-related problems. Despite that, studies on the effectiveness of adherence to the continuity of antenatal care (ANC) services are scarce. Therefore, this study aims to determine the effectiveness of the continuity of ANC services and the determinants of adverse pregnancy outcomes. A prospective follow-up study design was conducted from March 2020 to January 2021 in Northwest Ethiopia among randomly selected study subjects. Data were collected by trained data collectors using pre-tested structured questionnaires and analyzed using STATA Software version 14. A multilevel regression model was used to identify determinant factors, whereas the propensity score matching (PSM) model was used to look at the effectiveness of adherence to ANC services on adverse pregnancy outcomes. Among 2,198 study participants, 26.8% had adverse pregnancy outcomes, with 95% CI: 24.9-28.7 [abortion (6.1%; 95% CI: 5.1-7.1), low birth weight (11.5%; 95% CI: 10.2-12.9), and preterm birth (10.9; 95% CI: 9.6-12.3)]. Determinant factors were iron-folic acid supplementation (AOR = 0.52; 95% CI: 0.41, 0.68), delayed initiation of ANC visits at 4-6 months (AOR = 0.5; 95% CI: 0.32, 0.8), initiation of ANC visits after 6 months (AOR = 0.2; 95% CI: 0.06, 0.66), received four ANC visits (AOR = 0.36; 95% CI: 0.24, 0.49), an average time of rupture of the amniotic membrane of between 1 and 12 h (AOR = 0.66; 95% CI: 0.45, 0.97), and pregnancy-related problems (AOR = 1.89; 95% CI: 1.24, 2.9). As a treatment effect, completion of a continuum of visit-based ANC (ATET; β = -0.1, 95% CI: -0.15, -0.05), and continuum of care via space dimension (ATET; β = -0.11, 95% CI: -0.15, -0.07) were statistically significant on the reduction of adverse pregnancy outcomes. In the study area, the rate of adverse pregnancy outcomes was high. Even though adherence to the continuity of ANC services via time and space dimensions is effective in the prevention of adverse pregnancy outcomes, programmatically important factors were also detected. Therefore, key strategies for promoting the uptake of antenatal services and strengthening iron-folic acid supplementation are strongly recommended.

Active thrust tectonics along the western slope of the Central Andes southernmost Pampean flat-slab segment (∼33°S, Chile): The Cariño Botado fault system

Along the western slope of the Central Andes in the southernmost part of the Pampean flat-slab subduction zone segment (∼33°S), crustal Quaternary west-vergent reverse faults are found, but little is known about them. To better understand and characterize these faults, grouped as the Cariño Botado thrust fault system (CBF), we undertook a multidisciplinary study focused on remote sensing and field geomorphic and geologic mapping, sedimentary relationships, and fault characterization. Optically Stimulated Luminescence (OSL) and UPb dating samples were obtained from faulted deposits to constrain the timing of fault motion. We combined the mapping, fault relationship descriptions, and age control to understand this system better and quantify tectonic rates here for the first time. The main CBF is best expressed with Late-Cenozoic hanging wall fault rocks over thrusting Quaternary coarse-grained alluvial fan deposits, and the fault zone is found over a large area and with an altered fault zone (∼0.5–2 km wide). The principal reverse fault segment of the CBF is well exposed in creeks, with an average dip of 40°E and an associated vertical throw (up to the east) of the hanging wall from ∼3.2 m up to ∼30 m. Five OSL samples, taken from tilted and untilted alluvial fan deposits adjacent to the CBF's main fault, yielded ages between 2.5 ± 0.2 ka and 9.0 ± 0.7 ka, supporting Holocene activity and ∼4.9 m of fault slip in the last ∼8.7 ka. Ninety-nine detrital zircons from fluvial terrace deposits in the study area were dated using UPb ICPMS, giving mainly Oligo-Miocene ages. The youngest ages of detrital zircons are Quaternary (n = 3; ∼0.9–4.4 Ma), which indicates that CBF activity could have started as early as ∼0.9 Ma producing an accumulated hanging wall uplift of ∼130 m. The alignment of the fault profiles, creek and river knickpoints, and alluvial and fluvial deposits allows the most recent activity of the main CBF to be traced between 5 km and up to 15 km along the fault trace. Based on fault length, slip characteristics, and earthquake scaling relationships, earthquakes up to Mw 7.5 could be associated with the fault. Because of the clear relationship between the river incision, distribution of fluvial terraces, variation in sinuosity and stream power, and the location of the faults, we suggest that the tectonic uplift controls the hanging wall fluvial incision from ∼0.9 Ma to the present. The Quaternary (at least 0.9 Ma to present) active CBF shares geometric, structural, and rupture timing similarities with the nearby better-characterized San Ramón Fault system. The latter is located ∼50 km to the south along the eastern border of Santiago, the capital city of Chile. Both fault systems share a comparable morpho-structural setting with a consistent average N-S trend. Significant seismic hazard is associated with both the CBF and the San Ramon System, which may be linked structurally and temporally regarding previous surface ruptures and major earthquakes, and therefore remain important research targets.

Selecting a dependence for the approximation of experimental data on secondary creep and creep rupture strength

As a rule, for the evaluation of the mechanical characteristics of a metallic material by secondary creep and creep rupture strength, tests are carried out for uniaxial tension of cylindrical specimens under the influence of a stationary axial force. These mechanical characteristics include the experimental dependence of constant strain rate on nominal stress and the experimental dependence of rupture time on nominal stress. In order not to conduct a large number of experiments, so that these mechanical characteristics can be determined at any nominal stress, one of the two empirical dependencies is used, allowing the corresponding experimental dependences to be approximated with the smallest total error. As such empirical dependences, a power dependence with two material parameters and a fractional power dependence with four material parameters are considered, two of which acquire the definite physical meaning of starting creep stress (the maximum stress at which the strain rate is zero) and break creep stress (the minimum stress at which instantaneous rupture occurs). When choosing an empirical dependence, the author used experimental data obtained by him from mechanical tests for uniaxial tension of cylindrical VT5 and VT6 titanium alloy specimens at 650 °C. The calculated total errors testify that both empirical dependences satisfactorily approximate the considered experimental data.

Intraoperative challenges and complications of cataract surgery between cataract surgery alone and phacovitrectomy in eyes with diabetic retinopathy: efficacy of illuminated chopper-assisted cataract surgery

BackgroundTo compare the intraoperative challenges, complications, and operation time of illuminated chopper-assisted cataract surgery between cataract surgery only and phacovitrectomy in eyes with diabetic retinopathy.MethodsOne university hospital, retrospective case series. Two hundred ninety-five eyes of 295 consecutive patients with diabetic retinopathy who underwent cataract surgery only or phacovitrectomy were retrospectively reviewed. Intraoperative challenges and complications of cataract surgery were thoroughly analyzed by 3D viewing of digitally recorded videos. The pupil diameter, operation time, and improved efficacy (100/operation time × pupil diameter) were compared between the cataract surgery only and phacovitrectomy groups.ResultsOf the 295 eyes, 211 underwent cataract surgery only, and 84 underwent phacovitrectomy. Intraoperative challenges such as small pupil, miosis, or poor red reflex occurred more frequently (46 [21.8%] vs. 28 [33.3%], p = 0.029); pupil diameter was smaller (7.34 ± 0.94 vs. 6.89 ± 0.88 mm, p < 0.001) in the phacovitrectomy group than in the cataract surgery only group; however, rates of posterior capsule rupture and operation time were not different between the two groups (0 [0%] vs. 1 [1.2%], p = 0.285; 16.54 ± 2.65 vs. 16.31 ± 4.30 min, p = 0.434). Improved efficacy was higher in the phacovitrectomy group (0.85 ± 0.18 vs. 0.97 ± 0.28, p = 0.002).ConclusionsThe use of an illuminated chopper is a potential solution for diabetic cataract surgery, particularly in phacovitrectomy, by decreasing the use of supplemental devices, operation time, and posterior capsule rupture.Trial registrationRetrospectively registered.

Impact of noise on spinodal dewetting of liquid-liquid films

Spinodal dewetting provides fundamental insights into the physics at interfaces, such as van der Waals forces driving dewetting, dissipation processes or thermal fluctuations. The dewetting process of liquid bilayer systems still raises open problems involving two coupled moving interfaces. Comparison of experimental results of spinodally dewetting liquid polystyrene films from liquid polymethylmethacrylate substrates, with predictions from linear stability analysis, we demonstrate that both the spinodal wavelength and the rupture times show significant differences. Key for this discrepancy is the altered mode selection process due to the initial surface roughness of the liquid-air and liquid-liquid interfaces, which is perturbed by partially correlated colored noise in the linearly unstable region. The strong effect of noise on mode selection and rupture time is confirmed by comparing experimental results with numerical solutions of the full dynamic nonlinear model and suggest new strategies to include thermal fluctuations into modeling these processes.

Anatomy of the fetal membranes: insights from spinning disk confocal microscopy

PurposeThe fetal membranes are essential for the maintenance of pregnancy, and their integrity until parturition is critical for both fetal and maternal health. Preterm premature rupture of the membranes (pPROM) is known to be an indicator of preterm birth, but the underlying architectural and mechanical changes that lead to fetal membrane failure are not yet fully understood. The aim of this study was to gain new insights into the anatomy of the fetal membrane and to establish a tissue processing and staining protocol suitable for future prospective cohort studies.MethodsIn this proof of principle study, we collected fetal membranes from women undergoing vaginal delivery or cesarean section. Small membrane sections were then fixed, stained for nucleic acids, actin, and collagen using fluorescent probes, and subsequently imaged in three dimensions using a spinning disk confocal microscope.ResultsFour fetal membranes of different types were successfully processed and imaged after establishing a suitable protocol. Cellular and nuclear outlines are clearly visible in all cases, especially in the uppermost membrane layer. Focal membrane (micro) fractures could be identified in several samples.ConclusionThe presented method proves to be well suited to determine whether and how the occurrence of membrane (micro) fractures and cellular jamming correlate with the timing of membrane rupture and the mode of delivery. In future measurements, this method could be combined with mechanical probing techniques to compare optical and mechanical sample information.

Effect of Post-Welding Aging Treatment on the Microstructure and High-Temperature Properties of Inertia Friction Welded GH4065A Joint.

In this study, post-welding aging treatments were applied to a novel Ni-based superalloy GH4065A inertia friction welding (IFW) joint to improve its high-temperature properties. The effect of aging treatment on the microstructure and creep resistance of the IFW joint was systematically investigated. The results indicated that the original γ' precipitates in the weld zone almost completely dissolved during the welding process, and fine tertiary γ' precipitated during the subsequent cooling process. Aging treatment did not significantly change the characteristics of grain structures and primary γ' in the IFW joint. After aging, the size of tertiary γ' in the weld zone and secondary γ' in the base material increased, but their morphology and volume fraction did not change evidently. After 760 °C, 5 h aging treatment, the tertiary γ' in the weld zone of the joint grew from 12.4 nm to 17.6 nm. Correspondingly, the creep rupture time of the joint at 650 °C and 950 MPa increased from 7.51 h to 147.28 h, which is about 19.61 times higher than that of the as-welded joint. The creep rupture was more likely to occur in the base material instead of the weld zone for the IFW joint. This revealed that the creep resistance of the weld zone was significantly improved after aging due to the growth of tertiary γ'. However, increasing the aging temperature or extending the aging time promoted the growth of secondary γ' in the base material, and meanwhile, M23C6 carbides tended to continuously precipitate at the grain boundaries of the base material. It might decrease the creep resistance of the base material.

Machine learning assisted prediction of creep data of India specific reduced activation ferritic martensitic steel

The present study demonstrates the application of machine learning approach for predicting the creep deformation, rupture strain and rupture life of India specific reduced activation ferritic martensitic (INRAFM) steel. In this direction, various regression models were employed and found that the tree-based ensemble method (Extra trees regression (ETR)) offers better prediction of creep behaviour with the root mean square error (RMSE), average cross-validation score and coefficient of determination (R2) values of 0.00203, 0.979 and 0.996 respectively as compared to other models and which was used for further analysis of creep data. Initially, the creep data of INRAFM steel obtained from creep experiments for different stresses (σ) (200, 220, 240 and 260 MPa) at a test temperature (T) of 823 K was used to train the model for predicting strain values (ε) as output, namely ε = f (σ, T, t) approach, where t is time in hours (h). Subsequently, to assess the predictive capabilities of the model, the predicted data for the test condition of 250 MPa and 823 K was compared with experimental data. A good match was found between the predicted and experimental results with a correlation coefficient (Rcc) of 0.994. Later, the model was applied for predicting the creep curves at intermediate stress levels for the same temperature. Additionally, an effort has been made to predict the rupture time of the steel by providing strain as input variable, namely t = f (σ, T, ε) approach. The predicted rupture time values corresponding to different rupture strains are close to the experimental data. A comparison between both the predictive approaches (based on ε = f (σ, T, t) and t = f (σ, T, ε)) was carried out and presented. The results obtained in the present work reveal the potential of ETR approach for prediction of creep data.

Vessel Rupture Thresholds for Vessel-Bubble Interactions Using an Earthworm Vasculature Model.

Intravenous microbubble oscillation in the presence of ultrasound has the potential to yield a wide range of therapeutic benefits. However, the likelihood of vessel damage caused by mechanical effects has not been quantified as a function of the numerous important parameters in therapeutic ultrasound procedures. In this study, we examined the effects of microbubbles injected into the vasculature of the earthworm. It was found that the elastic properties of earthworm blood vessels are similar to those of arteries in older humans, and that earthworms are well suited to the large number of experiments necessary to investigate safety of procedures involving microbubble oscillation in sonicated vessels. Microbubbles were infused into earthworm vessels, and the rupture time during sonication was recorded as a function of ultrasound frequency, pulse repetition frequency and acoustic pressure. A modified mechanical index (MMI) was defined that successfully captured the trends in rupture probability and rupture time for the different parameter values, creating a database of vessel rupture thresholds. In the absence of bubbles, the product of MMI squared and rupture time was approximately constant, indicating a possible radiation-force effect. The MMI was an effective correlating parameter in the presence of bubbles, though the mathematical dependence is not yet apparent. The results of the study are expected to be valuable in designing more refined studies in vertebrate models, as well as informing computational models.

Heat Treatment of High-Performance Ferritic (HiperFer) Steels.

High-performance Ferritic (HiperFer) steels are a novel class of heat-resistant, fully ferritic, Laves phase precipitation hardened materials. In comparison to conventional creep strength-enhanced 9-12 wt.% Cr ferritic-martensitic steels, HiperFer features increased mechanical strength, based on a thermodynamically stable distribution of small (Fe,Cr,Si)2(Nb,W) Laves phase precipitates, and-owing to its increased chromium content of 17 wt.%-improved resistance to steam oxidation, resulting in superior temperature capability up to 650 °C. Previous publications focused on alloying, thermomechanical processing, and basic mechanical property evaluation. The current paper concentrates on the effect of heat treatment on microstructural features, especially Laves phase population, and the resulting creep performance. At 650 °C and a creep stress of 100 MPa, an increase in rupture time of about 100% was achieved in comparison to the solely thermomechanically processed state.

Endocardial Fibroelastosis as an Independent Predictor of Atrioventricular Valve Rupture in Maternal Autoimmune Antibody Exposed Fetus: A Systematic Review with Clinicopathologic Analysis

Neonatal lupus (NL) is a clinical syndrome that develops in the fetus as a result of maternal autoimmune antibodies. Congenital complete heart block (CHB) is the most common manifestation, while extranodal cardiac manifestations of NL, such as endocardial fibroelastosis (EFE) and myocarditis, are rare but more serious. Less is known about this atrioventricular valve rupture due to valvulitis as a consequence of maternal autoantibodies. We have described a case of cardiac neonatal lupus with an antenatally detected CHB patient who developed mitral and tricuspid valve chordal rupture at 45 days of age. We compared the cardiac histopathology and the fetal cardiac echocardiographic findings of this case with another fetus that was aborted after being antenatally diagnosed with CHB but without valvar rupture. A narrative analysis after a systematic review of the literature regarding atrioventricular valve apparatus rupture due to autoimmune etiology along with maternal characteristics, presentation, treatment, and outcome have been discussed in this article. To describe published data on atrioventricular valve rupture in neonatal lupus, including clinical presentation, diagnostic evaluation, management, and outcomes. We conducted a PRISMA-compliant descriptive systematic examination of case reports that included accounts of lupus during pregnancy or in the newborn period that resulted in an atrioventricular valve rupture. We gathered information on the patient's demographics, the details of the valve rupture and other comorbidities, the maternal therapy, the clinical course, and the results. We also used a standardized method to evaluate the cases' quality. A total of 12 cases were investigated, with 11 cases drawn from 10 case reports or case series and 1 from our own experience. Tricuspid valve rupture (50%) is more common than mitral valve rupture (17%). Unlike mitral valve rupture, which occurs postnatally, the timing of tricuspid valve rupture is perinatal. A total of 33% of the patients had concomitant complete heart block, while 75% of the patients had endocardial fibroelastosis on an antenatal ultrasound. Antenatal changes pertaining to endocardial fibroelastosis can be seen as early as 19 weeks of gestation. Patients with both valve ruptures generally have a poor prognosis, especially if they occur at close intervals. Atrioventricular valve rupture in neonatal lupus is rare. A majority of patients with valve rupture had antenatally detected endocardial fibroelastosis in the valvar apparatus. Appropriate and expedited surgical repair of ruptured atrioventricular valves is feasible and has a low mortality risk. Rupture of both atrioventricular valves occurring at close intervals carries a high mortality risk.