Internal Failure Research Articles

Study on the Application of Internal Control in the Management of Urban Commercial Banks

In February 2021, Baoshang Bank, whose total asset size had exceeded 500 billion, exited the stage of history with more than 200 billion in unpayable debts. Now look back on its life, from the clouds fell to the bottom. However, there are traces of its causes. Weak supervision of funds, the organizational structure of the organization is a sham, excessive concentration of equity internal governance failure eventually became the key to its demise. Therefore, this paper will take the current situation of rising non‐ performing loan rate of urban commercial banks as the entry point to discuss the importance of internal governance and make suggestions for the establishment of a sound internal control system in urban commercial banks.

A novel approach for anterior cruciate ligament tibial avulsion fracture: arthroscopic modified suture bridge fixation technique.

Anterior cruciate ligament (ACL) tibial avulsion fracture is a rare injury, which usually happens in adults with traffic accidents or sports injuries. Surgery interventions are common treatment methods, they can restore knee function and help to return to normal life. In this study, we described an arthroscopic modified suture bridge fixation technique for ACL tibial avulsion fractures and explored the feasibility and therapeutic effects. This retrospective study reviewed data from January 2020 to May 2022. Data were collected on 18 patients (10 males and 8 females) with ACL tibial avulsion fractures and underwent arthroscopic modified suture bridge fixation technique. The study analyzed surgical data about intraoperative blood loss, operation time, hospital stay, fracture healing time, and visual analog scale (VAS). Functional evaluation of the knee joint was performed using the anterior drawer test, Lysholm knee scoring scale, International Knee Documentation Committee (IKDC), and knee range of motion (ROM). All 18 patients were followed up between 12 and 20 months, with an average of 15.22 ± 1.96 months. The intraoperative blood loss was approximately 15-40 mL, averaging 25.78 ± 6.19 mL. The operation time was 65-85min, with a mean of 74.89 ± 4.86min. The hospital stay of patients was 3-5 days, with a mean of 3.89 ± 0.76 days. The mean fracture healing time was 8-12 weeks after surgery, with a mean of 9.22 ± 1.7 weeks. All incisions healed grade I without infection. There were no internal fixation failures, neurovascular injuries, and lower extremity deep venous thrombosis. The anterior drawer test was negative in all patients. At the final follow-up, the mean VAS score was 0-3, averaging 1.56 ± 0.71. The Lysholm score of the injured knee was 89-96, with an average of 92.50 ± 2.50; the IKDC score was 88-93, with an average of 90.44 ± 1.89; the knee ROM was 110-126°, with an average of 120.67° ± 4.31°. Results demonstrated that the modified suture bridge fixation technique under arthroscope could provide reliable fixation and favorable clinical effects for ACL tibial avulsion fractures. This is a simple, minimally invasive, effective, and clinically applicable surgical method for ACL tibial avulsion fracture.

Research on internal leakage detection of the ball valves based on stacking ensemble learning

Abstract Natural gas is an important clean energy source that is mainly transported through pipelines. The ball valve is a crucial piece of control equipment for the pipeline transportation system for natural gas, and the failure of internal leakage of the ball valve will seriously affect the natural gas transmission and increase the risk of sudden safety accidents. In response to the problems of the limitations of a single machine learning model in the traditional ball valve internal leakage rate prediction methods and failure to qualitatively analyze unilateral and bilateral internal leakage recognition of ball valve, a study of ball valve internal leakage detection based on Stacking ensemble learning is proposed. A total of 15 time and frequency domain feature parameters were obtained by feature extraction of 125 and 96 sets of raw acoustic emission signals from the ball valve; the parameters of a single machine learning model were adjusted by Bayesian optimization grid search. An internal leakage rate prediction model and an internal leakage recognition model are constructed, and the proposed model is compared and analyzed with a single model through a field ball valve internal leakage test. The results indicate that the Stacking ensemble learning model outperforms each single machine learning model in terms of SMAPE (17.2583), RMSE (1.1009), and MAE (0.9375) for internal leakage rate prediction. The Stacking ensemble learning model outperformed the single machine learning model in terms of accuracy (1), recall (1), precision (1), FAR(0), and F1-score (1) for internal leakage recognition. Stacking ensemble learning significantly enhances the model's ability to detect internal ball valve leaks.

Economic consequences of inland waterway disruptions in the Upper Mississippi River region in a changing climate

Inland waterway locks have become significant bottlenecks in waterway networks worldwide due to the disruptions caused by aging infrastructure and climate change. While these locks have traditionally received attention for traffic issues, the disruptive impact on the regional economy remains unclear. This study addresses this knowledge gap by assessing the economic impacts of inland water transportation system failures, specifically focusing on disruptions in agricultural commodities within the Upper Mississippi River–Illinois River (UMR–IR) region. These disruptions encompass both unscheduled climate-induced extreme weather events and scheduled maintenance and repair work due to internal system failure. To capture the spatial interdependence between the regional economy and shipping rate changes caused by disruptions, we developed an integrated modeling approach. This approach combines spatial econometric modeling and multi-regional computable general equilibrium modeling techniques. Detailed weekly data from 2013 to 2021, including variations in inland barge rates and environmental conditions, were utilized. The assessment reveals that lock closure events in the UMR-IR region have severe economic consequences, impacting both the region itself and beyond. Conversely, transportation resilience achieved through modal substitution from barge to rail services during disruptive events can substantially reduce GDP losses. Specifically, such resilience measures can reduce GDP losses in the UMR-IR region by 6.6–24.2% and in the rest of the USA by 5.2–19.5%. Overall, these research findings carry significant implications for future planning and investment in inland waterway systems.

Low energy impact damage characteristics of epoxy coating on the surface of sandwich composites

AbstractWhen composite honeycomb sandwich structures are subjected to low energy impacts, the upper panel or the honeycomb core often suffers large damages, which are invisible, but affects the structural safety. To achieve non‐destructive detection of these damages, an epoxy resin film (ERF) was designed as a functional coating to display the internal failure features on structure surface. The effect of low energy impacts on the damage modes of the ERF was first investigated, and then the correspondence between the ERF damage characteristics and the structural internal failure was established. Simulation and experimental results showed that with the increase of impact energy, cracks on the ERF expanded from the radial radiation with a small extension range to the circumferential pattern with an increased damage area. Meanwhile, localized delamination appeared inside the upper panel, while the degree of flexure and crushing damage to the core continued to increase. Based on the analysis of the crack extension pattern of the ERF and the damage state of the upper panel and honeycomb core, a specific link between the ERF crack characteristics and the internal damages to the sandwich structure was obtained, which might offer a novel non‐destructive testing method for composite impact damages.Highlights Low energy impact damage in honeycomb sandwich structures was a concern. Impact damage response of epoxy resin film on sandwich composites was studied. Crack extension of the film showed a particular change from radial to annular. Specific link between film crack and sandwich structure damage was established. The results would be helpful for damage detection in sandwich composites.

Splitting Tensile Mechanical Performance and Mesoscopic Failure Mechanisms of High-Performance Concrete under 10-Year Corrosion from Salt Lake Brine

In regions characterized by the challenging combination of brine corrosion in the salt lakes and river sand with alkali silica reaction (ASR) activity in areas of the Northwest, high-performance concrete (HPC) formulated with high-volume composite mineral admixtures as ASR suppression measures has been preferred for civil engineering structures in the region. This study investigates the splitting tensile strength, corrosion products, microscopic structure characteristics, and mesoscopic mechanical mechanisms of splitting failure of such HPC under 10-year corrosion from salt lake brine. The relationship between mechanical properties and corrosion damage, as well as the characteristics of internal crack propagation paths and failure mechanisms of HPC under splitting load, are explored. The findings reveal that as the alkali content within HPC rises, corrosion damage intensifies, resulting in a reduction in splitting tensile strength. Moreover, a linear association between mechanical properties and corrosion damage is observed. Microscopic structural analysis and numerical simulation of the splitting failure process of HPC elucidate that while the substantial presence of mineral admixtures effectively suppresses the ASR risk associated with alkali-reactive aggregates in concrete, uneven ASR gel products persist. These discontinuous micro-fine interface cracks induced by the gel products and the cracks induced by the gel products around the selective alkali-active aggregate particles distributed in the local area are the initiation sources of mortar cracks in HPC splitting failure. In terms of the overall failure state observed during the concrete splitting process, mortar cracks manifest two distinct extension paths: along the coarse aggregate interface and directly through the aggregates themselves. Notably, a greater proportion of coarse aggregates are directly penetrated by mortar cracks, as opposed to the number of interface failures bypassing coarse aggregates. More importantly, the above work establishes a theoretical reference in three dimensions: macroscopic, mesoscopic, and microscopic, for studying concrete corrosion damage in complex environments such as salt lake brine corrosion and ASR inhibition.

Stopping Hamburglars: Applying Effective Internal Control

ABSTRACT Understanding effective internal control is vital for accounting and business students. Examples of fraud and loss through poor internal control are widespread in practice. The learning objectives of this teaching case focus on improving students’ ability to comprehensively evaluate internal control practices and suggest and justify new practices where applicable. The McDonald’s Monopoly fraud is a real-life example of a situation where multiple internal control failures had substantial financial and reputational consequences for McDonald’s, particularly its outsourcing partners involved in operationalizing the monopoly game. We use this factual case to illustrate control system shortcomings, allowing students to evaluate internal control and suggest internal control techniques with reference to all five components of the Committee of Sponsoring Organizations of the Treadway Commission (COSO) Internal Control—Integrated Framework. JEL Classifications: A22.

Potential effects of internal dam-break in Stare Miasto Reservoir in Poland

Study regionThe research object is located in Wielkopolska province (Poland), which is well-known for its rural character and scarcity of water. To prevent droughts, small reservoirs are installed in local watersheds. It enables control of water conditions for agriculture and improvement of local climate. The main challenge is prevention from the deposition of sediments in a reservoir. To minimize this threat, the specific constructions of the reservoir are applied, e.g. internal dams. Study focusThe Stare Miasto reservoir consists of an internal dam with the upper zone separated. The highway bridge split the main part. In 2014 a flood wave propagated through the reservoir. The crest of the internal dam was shifted generating a potential risk of internal dam failure. The consequences of such an event were analyzed using a two-dimensional hydrodynamic numerical tool that solves the shallow water equations with finite volume method on unstructured mesh. New hydrological insight for the regionThe results obtained prove that the dam break increases the risk of bridge instability. The shear stresses generated during break of internal dam may exceed 50 N/m2, what cause danger of deep scour generation under and below the construction. Unexpectedly, the existence of the bridge decreased the threat of the main dam overtopping. The study may be a valuable inspiration for the design of new reservoirs inevitable in controlling water resource conditions in the region.

Study on the therapeutic effect of Kirschner wire tension band combined with anchor cross-stitch technique in the treatment of comminuted patellar inferopolar fractures.

Fractures of the inferior patellar pole, unlike other patellar fractures, present challenges for traditional surgical fixation methods. This article introduces the clinical technique and outcomes of using Kirschner wire tension band combined with anchor screw cross-stitch fixation for comminuted inferior patellar pole fractures. This retrospective case series study included 14 patients with comminuted inferior patellar pole fractures treated at our institution from September 1, 2020, to April 30, 2022. All patients underwent surgery using the Kirschner wire tension band with anchor screw cross-stitch technique. Follow-up assessments involved postoperative X-rays to evaluate fracture healing, as well as clinical parameters such as healing time, Visual Analog Scale (VAS) scores, range of motion (ROM), and Bostman scores. All patients were followed for an average of over 12 months, with no cases of internal fixation failure. Knee joint stability and function were excellent. X-rays revealed an average healing time of approximately 10.79 ± 1.53 weeks, hospitalization lasted 5.64 ± 1.15 days, surgery took approximately 37.86 ± 5.32 minutes, and intraoperative blood loss was 33.29 ± 8.15 ml. One patient experienced irritation from the internal fixation material. At the final follow-up, the Bostman score averaged 28.29 ± 0.83, knee joint flexion reached 131.07° ± 4.88°, all patients achieved full knee extension, and the VAS score was 0.36 ± 0.63. Kirschner wire tension band with anchor screw cross-stitch fixation for comminuted inferior patellar pole fractures delivered satisfactory clinical outcomes. This surgical method, characterized by its simplicity and reliability, is a valuable addition to clinical practice.

Research on comprehensive analysis of patient comfort and complication rate using haemodialysis indwelling needles in AVF puncture in haemodialysis treatment.

Traditional needles for haemodialysis access can cause complications and discomfort. Indwelling needles may have advantages, but their efficacy needs to be investigated. Our study sought to compare the safety and efficacy of indwelling needles to traditional needles for haemodialysis access. A single-center retrospective study at the Pingyang County Hospital of Traditional Chinese Medicine included 70 haemodialysis patients. The intervention group used indwelling needles, whereas the control group used traditional needles. The rate of complications, limb mobility, blood chemistry, puncture success rates, operation times, haemostasis times, pain and comfort scores, and internal fistula failure rates were all compared. Overall, complication rates were slightly higher in the control group, but not statistically significant. Both groups improved their limb mobility and blood chemistry, but there were no significant differences. The intervention group had significantly higher puncture success rates (88.4% vs. 80.0%), shorter operation times (65.4 vs. 72.3 seconds), and faster haemostasis times (23.7 vs. 28.2 seconds) than the control group. Patients in the intervention group experienced less pain (3.7 vs. 4.2) and more comfort (8.1 vs. 7.5). The intervention group had slightly lower internal fistula failure rates (2.9% vs. 5.7%), but the difference was not statistically significant. Indwelling needles appear to improve puncture efficiency and patient comfort during hemodialysis.

Topological perturbations on resilience of the world trade competition network

Network resilience refers to a system’s capability to adapt its functions to ensure continuity of essential operations amidst external environmental shifts or internal failures. The resilience of the world trade network faces structural disturbances, such as dynamic changes in the internal and external environments, increasing trade barriers and changes in competition between countries, which is an issue worth exploring. In this study, we introduce a world trade competition network that reflects export competition between two countries. We employ a network dynamics model to assess the resilience of this global trade competition network, focusing on the influence of topological disturbances. The eight distinct types of topological perturbations analyzed include nodes representing countries, links symbolizing inter-country competition, and weights indicative of the intensity of this competition. Our findings reveal that the intensity of export competition between countries significantly influences the resilience of the global trade competition network. Specifically, experimental outcomes indicate that network resilience declines more rapidly when nodes are removed sequentially based on higher weighted degrees than when based on lower ones. Similarly, in link perturbation scenarios, removing links associated with higher competition intensity first leads to a more precipitous decrease in network resilience when the network is otherwise stable. Furthermore, in weight alteration scenarios, networks maintaining a higher ratio of high-intensity competition links demonstrate greater stability compared to those with a reduced proportion of such links. Consequently, sustaining a robust level of export competition between countries is crucial for preserving the stability of the network.

Experimental study on the internal short circuit and failure mechanism of lithium-ion batteries under mechanical abuse conditions

The safety issues of lithium-ion batteries under mechanical abuse conditions have attracted widespread attention due to their high uncertainty and risk. This research takes cylindrical lithium-ion batteries as the research object and conducts three-point bending tests on cylindrical lithium-ion batteries with different states of charge (SOC), electrode thicknesses and electrode materials. The mechanical response, voltage changes, temperature changes during the loading process of the battery, and the microstructural changes of the battery's electrodes and separator after the bending test were examined. The results show that the maximum load-bearing capacity of the battery and the displacement corresponding to the short circuit decreases with the SOC of battery; the higher the battery SOC means a faster average temperature rise rate of the battery. When the SOC is higher than 60 %, the battery will experience violent thermal runaway phenomena such as explosions and spouting fire after bending tests. The mass loss rate of the battery is also greatly affected by the battery SOC and the electrode thickness, however, electrode material have almost no effect on the mass loss rate of the battery. According to the SEM images of the electrodes, it is found that short circuits cause graphite particles to break, separators to close and electrolytes oxidize on the surface of positive electrode particles. After triggering the internal short circuit, more broken particles are observed in the positive electrode material of the battery with thicker electrodes and the surface roughness of the broken particles is higher. By comparing the electrode changes of LFP and NCM, it is found that the intensity of the internal electrochemical reactions in NCM is far greater than that in LFP. The research results provide theoretical insights for understanding the electrothermal characteristics and mechanical integrity of lithium-ion batteries under mechanical abuse, which can shed light on the design and optimization of high-performance and safe lithium-ion batteries.

Selecting conduits for coronary artery bypass grafting: caution regarding the right internal mammary artery

This narrative review summarizes the angiographic and clinical outcome results of the most common coronary artery bypass grafting (CABG) conduits. The left internal mammary artery is the preferred first conduit to bypass the left anterior descending artery due to superior long-term survival and graft patency. Recent studies suggest the radial artery may be the preferred second conduit for the circumflex or right coronary artery territories, challenging the belief that the right internal mammary artery is the best choice. Despite their historical high failure rates, saphenous vein grafts continue to be widely used as secondary conduits. Several recent studies report suboptimal rates of right internal mammary artery graft failure, with clinical outcomes comparable to or worse than saphenous veins. The suboptimal rates of RIMA graft failure may be attributed to several factors such as improvements in vein graft failure rates, the use of in situ and non-left anterior descending artery grafting configurations, and skeletonized harvesting techniques. While observational studies favor multiple over single arterial grafting, randomized studies are needed for confirmation. The ongoing Randomized comparison of the clinical Outcome of single vs. Multiple Arterial grafts (ROMA) trial aims to determine if multiple arterial grafting reduces major adverse cardiovascular events and mortality and how secondary conduit selection influences these outcomes. Greater adoption of arterial grafting strategies is likely to come from high-quality evidence of benefit and safety from ongoing and future large pragmatic trials.

Correlation between combined deflection angle classification adduction typing and complications after internal fixation of adduction femoral neck fracture

To analyze the correlation between postoperative complications and combined deflection angle classification adduction type (CDAC-ADT) of femoral neck fractures after cannulated screw internal fixation. The clinical data of 121 patients with CDAC-ADT femoral neck fracture admitted between January 2018 and December 2021 and met the selected criteria were retrospectively analyzed. There were 69 males and 52 females, the age ranged from 19 to 79 years (mean, 48.1 years). The causes of injury included 52 cases of traffic accident, 24 cases of falling from height, and 45 cases of fall. The time from injury to operation ranged from 2 to 12 days, with an average of 6.0 days. Among them, there were 18 cases of CDAC-ADT type Ⅰ, 46 cases of type Ⅱ, and 57 cases of type Ⅲ; 6 cases of Garden type Ⅱ, 103 cases of type Ⅲ, and 12 cases of type Ⅳ; and according to the location of the fracture line, there were 26 cases of subcapitate type, 88 cases of transcervical type, and 7 cases of basal type. All patients were treated with cannulated screw internal fixation. The occurrence of complications (including internal fixation failure, fracture nonunion, and osteonecrosis of the femoral head) was recorded, and the correlation between complications and CDAC-ADT typing, Garden typing, and fracture line location were analyzed. The patients were followed up 8-44 months, with a mean of 24.9 months. There were 10 cases of internal fixation failure, 7 cases of fracture nonunion, and 30 cases of osteonecrosis of the femoral head after operation. Correlation analysis showed that patients' CDAC-ADT typing was significantly correlated with the overall incidence of complication and the incidence of internal fixation failure, fracture nonunion, and osteonecrosis of the femoral head ( P<0.05), and the Pearson coefficient of contingency were 0.435, 0.251, 0.254, and 0.241, respectively. Garden typing did not correlate with the overall incidence of complication and the incidence of internal fixation failure and fracture nonunion ( P>0.05), but correlated with the incidence of osteonecrosis of the femoral head ( P<0.05), and the Pearson coefficient of contingency was 0.251. Fracture line position typing had no correlation with the overall incidence of complication and the incidence of internal fixation failure, fracture nonunion, and osteonecrosis of the femoral head ( P>0.05). CDAC-ADT typing has obvious correlation with postoperative complications of femoral neck fracture and can be used to predict complications of femoral neck fracture.

Comparison of effectiveness of three surgical methods in treatment of Pauwels type Ⅲ femoral neck fracture in young and middle-aged patients

To compare the effectiveness of three surgical methods in the treatment of Pauwels type Ⅲ femoral neck fracture in young and middle-aged patients, in order to provide reference for clinical selection of appropriate surgical methods. The clinical data of 103 patients with Pauwels type Ⅲ femoral neck fracture who met the selection criteria between June 2018 and December 2021 were retrospectively analyzed. The fractures were fixed with hollow screws in an inverted triangular shape (37 cases, hollow screw group), hollow screws in an inverted triangular shape combined with eccentric shaft screw (34 cases, eccentric shaft screw group), and hollow screws in an inverted triangular shape combined with medial support plate (32 cases, support plate group). There was no significant difference in age, gender, cause of injury, body mass index, time from injury to operation, side of the fracture, and Garden classification, whether they were in traction preoperatively, and other baseline data between groups ( P>0.05). The operation time, intraoperative blood loss, the number of fluoroscopy, the length of hospital stay, early postoperative complication and postoperative weight-bearing time of the three groups were recorded. Harris score was used to evaluate joint function at 6 and 12 months after operation, and the difference between the two time points (change value) was calculated for comparison between groups. X-ray films were reviewed to evaluate the quality of fracture reduction (Garden index) and healing, as well as the occurrence of internal fixation failure and femoral head necrosis. The patients of the three groups were successfully completed. Compared with the hollow screw group and the eccentric shaft screw group, the operation time and intraoperative blood loss of the support plate group significantly increased, the number of fluoroscopy reduced, and the quality of fracture reduction was better, the differences were significant ( P<0.05). The operation time, intraoperative blood loss, and the number of fluoroscopy of the hollow screw group were less than those of the eccentric shaft screw group, the differences were significant ( P<0.05). There was no significant difference in the length of hospital stay between groups ( P>0.05). All patients in the three groups were followed up 21-52 months, with an average follow-up time of 36.0 months, and there was no significant difference between groups ( P>0.05). The incisions of all patients healed by first intention. Imaging reexamination showed that there was no significant difference in the incidence of fracture nonunion between groups ( P>0.05). The fracture healing, partial weight-bearing, and full weight-bearing were significantly earlier in the eccentric shaft screw group and the support plate group than in the hollow screw group ( P<0.05). There was no significant difference in change value of Harris score, the incidence of postoperative deep venous thrombosis and femoral head necrosis between groups ( P>0.05); however, the incidence of internal fixation failure in the support plate group and the eccentric shaft screw group was significantly lower than that in the hollow screw group ( P<0.05). The incidence of postoperative lateral thigh irritation in the support plate group was significantly lower than that in the hollow screw group ( P<0.05); there was no significant difference between the eccentric shaft screw group and the other two groups ( P>0.05). The overall incidences of postoperative complications in the eccentric shaft screw group and the support plate group were significantly lower than that in the hollow screw group ( P<0.05). For young and middle-aged patients with Pauwels type Ⅲ femoral neck fracture, compared with simple hollow screw fixation in an inverted triangular shape, combined with medial support plate or eccentric shaft screw internal fixation can shorten the fracture healing time, reduce the incidences of postoperative complication, more conducive to early functional exercise of the affected limb; at the same time, the operation time and blood loss of combined eccentric shaft screw internal fixation are less than those of combined medial support plate internal fixation, so the hollow screw in an inverted triangular shape combined with eccentric shaft screw fixation may be a better choice.

Treatment of irreducible intertrochanteric femoral fracture in elderly by folding top technique combined with right-angle pliers prying and pulling under G-arm X-ray fluoroscopy

To explore the effectiveness of irreducible intertrochanteric femoral fracture in the elderly by treating with folding top technique and right-angle pliers prying and pulling under G-arm X-ray fluoroscopy. The clinical data of 74 elderly patients with irreducible intertrochanteric femoral fracture admitted between February 2016 and December 2022 and met the selection criteria were retrospectively analyzed. Among them, 38 cases were treated with folding top technique combined with right-angle pliers prying and pulling under G-arm X-ray fluoroscopy and intramedullary nailing fixation (study group), and 36 cases were treated with limited open reduction combined with other reduction methods and intramedullary nailing fixation (control group). There was no significant difference in baseline data between the two groups, such as age, gender, cause of injury, affected side and classification of fractures, complicated medical diseases, and time from injury to operation ( P>0.05). The operation time, intraoperative blood loss, hospital stay, fracture reduction time, fracture healing time, and complications of the two groups were recorded and compared. The quality of fracture reduction was evaluated by Baumgaertner et al. and Chang et al. fracture reduction standards. Patients in both groups were followed up 10-14 months, with an average of 12 months. The operation time and intraoperative blood loss in the study group were significantly less than those in the control group ( P<0.05), there was no significant difference in hospital stay between the two groups ( P>0.05). At 2 days after operation, according to the fracture reduction standards of Baumgaertner et al. and CHANG Shimin et al., the quality of fracture reduction in the study group was better than that in the control group, and the fracture reduction time in the study group was shorter than that in the control group, with significant differences ( P<0.05). After operation, the fractures of the two groups all healed, and there was no significant difference in healing time between the two groups ( P>0.05). During the follow-up, there was no complication such as incision infection, internal fixation failure, deep venous thrombosis of lower limbs, intramedullary nail breakage, spiral blade cutting, or hip varus in the two groups, except for 2 cases of coxa vara in the control group. For the irreducible intertrochanteric femoral fracture, using folding top technique combined with right-angle pliers prying and pulling under G-arm X-ray fluoroscopy can obviously shorten the operation time, reduce the intraoperative blood loss, and improve the quality of fracture reduction.

Effectiveness of injured vertebra fixation with inclined-long pedicle screws combined with interbody fusion for thoracolumbar fracture dislocation with disc injury

To investigate the effectiveness of injured vertebra fixation with inclined-long pedicle screws combined with interbody fusion for thoracolumbar fracture dislocation with disc injury. Between January 2017 and June 2022, 28 patients with thoracolumbar fracture dislocation with disc injury were underwent posterior depression, the injured vertebra fixation with inclined-long pedicle screws, and interbody fusion. There were 22 males and 6 females, with a mean age of 41.4 years (range, 22-58 years). The causes of injury included falling from height in 18 cases, traffic accident in 5 cases, and bruise in 5 cases. Fracture segment included 1 case of T 11, 7 cases of T 12, 9 cases of L 1, and 11 cases of L 2. According to the American Spinal Injury Association (ASIA) scale, the spinal injuries were graded as grade A in 4 cases, grade B in 2 cases, grade C in 11 cases, and grade D in 11 cases. Preoperative spinal canal encroachment ratio was 17.7%-75.3% (mean, 44.0%); the thoracolumbar injury classification and severity score (TLICS) ranged from 9 to 10 (mean, 9.9). Seventeen patients were associated with other injuries. The time from injury to operation ranged from 1 to 4 days (mean, 2.3 days). The perioperative indicators (operation time, intraoperative blood loss, and the occurrence of complications), clinical evaluation indicators [visual analogue scale (VAS) score and Oswestry Disability Index (ODI)], radiologic evaluation indicators [anterior vertebral height ratio (AVHR), kyphosis Cobb angle (KCA), intervertebral space height (ISH), vertebral wedge angle (VWA), displacement angle (DA), and percent fracture dislocation displacement (PFDD)], neurological function, and interbody fusion were recorded. The operation time was 110-159 minutes (mean, 130.2 minutes). The intraoperative blood loss was 200-510 mL (mean, 354.3 mL). All incisions healed by first intention, and no surgical complications such as wound infection or hematoma occurred. All patients were followed up 12-15 months (mean, 12.7 months). The chest and lumbar pain significantly relieved, VAS scores and ODI after operation were significantly lower than those before operation, and further decreased with the extension of postoperative time, with significant differences ( P<0.05). At last follow-up, the ASIA classification of neurological function of the patients was grade A in 3 cases, grade B in 1 case, grade C in 1 case, grade D in 10 cases, and grade E in 13 cases, which was significantly different from preoperative one ( Z=-4.772, P<0.001). Imaging review showed that AVHR, KCA, ISH, VWA, DA, and PFDD significantly improved at 1 week, 3 months and last follow-up ( P<0.05). There was no significant difference between different time points after operation ( P>0.05). At last follow-up, according to the modified Brantigan score, all patients achieved good intervertebral bone fusion, including 22 complete fusion and 6 good intervertebral fusion with a few clear lines. No complications such as internal fixation failure or kyphosis occurred during follow-up. The injured vertebra fixation with inclined-long pedicle screws combined with interbody fusion is an effective treatment for thoracolumbar fracture dislocation with disc injury, which can correct the fracture dislocation, release the nerve compression, restore the injured vertebral height, and reconstruct spinal stabilization.

Influence of surface condition, cycling frequency and ferritic zones on the high and very high cycle fatigue properties of a pearlitic steel

In the present work, the high and very high cycle fatigue (HCF/VHCF) properties of pearlitic steel R350HT are investigated. Servo-hydraulic (cycling frequency between 15 Hz and 60 Hz) and ultrasonic (19 kHz) fatigue tests were performed with different surface conditions (fine turned, mechanically polished and electropolished). At a load ratio of R = −1, solely failures in the HCF regime were found for all surface conditions, although runout specimens were loaded with more than 1010 cycles, and crack initiation was exclusively at the surface. At R = 0.1, in contrast, mechanically polished specimens showed internal failures for lifetimes between 106 and 109 cycles. The origin of fracture in the interior was identified as distributed ferritic phases embedded in the harder pearlitic microstructure. Crack initiation from ferritic zones could be explained by their larger size relative to inherent defects such as nonmetallic inclusions and precipitates. The absence of turning grooves in combination with compressive residual stresses near the surface of mechanically polished specimens led to an increase in HCF strength compared with fine-turned and electropolished specimens and facilitated VHCF failure from the interior. No frequency effect was observed when crack initiation originated from turning grooves or artificial surface defects, but slightly higher fatigue strengths were determined for electropolished specimens at 19 kHz than at conventional cycling frequency. This can be explained by the strain-rate sensitivity of ferrite where fatigue cracks preferentially initiate. Additional tests with specimens containing artificially introduced micro-holes were performed to systematically study material's defect tolerance and to quantify the mean-stress sensitivity.

Couple effects of multi-impact damage and CAI capability on NCF composites

Abstract In this study, the mechanical properties of non-crimp fabric (NCF) composite laminates under low-velocity impact and compression after impact (CAI) tests were studied by Scanning electron microscopy (SEM) and Digital image correlation (DIC) techniques. The impact response under different impact times, impact angles, and impact distance is studied. Similarly, in CAI test, DIC technique is used to reveal the whole process of NCF composite compression failure, and SEM is used to reveal the microscopic failure form. The experimental results show that the impact damage process of NCF composites has strong directivity. The concrete manifestation is that the internal failure will extend along the paving direction at the failure layer. The peak load generated under 20 J impact energy is about 1/2 of that under 40 J impact energy. The impact distance is one of the important factors affecting the coupling effect of multiple impacts, and the impact angle has little effect on the internal damage extension. The proportion of internal damage area also supports the relevant view, that is, the average difference in the proportion of internal damage area under different impact distance is about 5%, while the average difference in the proportion of internal damage area under different impact angles is about 3%. During the compression process, the main failure mode is shear failure and the failure mode is brittle fracture. The oblique fracture occurs only when the oblique is 45° and the impact distance is large (50 mm). The impact angle has little effect on the residual compression performance of NCF.

Numerical evaluation of the internal fracture mechanism of the single PBL shear connector considering the effects of position and strength of the transverse rebar

AbstractThe perfobond (PBL) shear connector reinforced with transverse rebar effectively contributes to sufficient ductility, bearing capacity, and anti‐fatigue behavior to hybrid structures. The construction practice involves the placement of the transverse rebar at the bottom position within the concrete dowel, whereas past studies employed transverse rebar in the center of the dowel; hence, there exists a gap between literature and design practices. Furthermore, there is no specific information in the design guidelines for hybrid structures on the influence of the position of the transverse rebar. Therefore, the current research deals with the analytical investigations employing the coupled Rigid Body Spring Model (RBSM) and the nonlinear solid Finite Element Method (FEM) that encompass the internal fracture behavior of concrete with the various parameters of transverse rebar, particularly the position and strength, to recognize the failure mechanism. It was determined that the numerical model accurately captured the test shear capacity and failure modes. The internal failure process of a specimen with transverse rebar at the bottom position, identical to actual field practice, revealed that as the height of the concrete region above the rebar rises, more compressive stresses in a trapezoidal manner are being generated, leading to an enhancement of the deformation capacity. Furthermore, it was confirmed that the specimen with the transverse rebar inserted at the bottom generates the greatest axial force, which is followed by the greatest shear capacity.