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Carbon fiber-reinforced polymers (CFRPs) are widely used in high-performance applications, but their inherent brittleness and susceptibility to impact damage remain critical challenges. This study investigated the effect of core–shell rubber (CSR) particles as impact modifiers on the mechanical properties of CFRPs and evaluated patch repair techniques for damaged CFRP panels. Mechanical tests, including flexural, tensile, short-beam, fracture toughness, and impact tests, were conducted on reference and CSR-modified specimens to assess their structural performance. The CSR-modified samples demonstrated significant improvements in energy absorption and fracture toughness, with a 50% increase in impact strength and up to 181% improvement in absorbed energy during Mode I fracture testing. However, slight reductions in flexural and tensile strengths were observed due to the softening effect of CSR particles. Fracture surface analysis revealed distinct failure mechanisms, with Scanning Electron Microscopy imaging showing consistent fiber pull-out behavior in tensile and flexural tests, but more stable delamination propagation in CSR-modified specimens during short-beam shear tests. Patch repair effectiveness was assessed through drop-weight impact tests on damaged panels repaired with patches containing CSRs of two thicknesses. Patches of equal thickness to the damaged panel successfully restored structural integrity and enhanced energy absorption by 37% compared with the reference samples, while thinner patches (as a suggestion to reduce production costs) failed to withstand impact loads effectively. Non-destructive testing (NDT) via ultrasonic C-scans confirmed reduced delamination and damage depth in CSR-modified repaired panels, validating the toughening effect of CSR particles. These findings demonstrate the potential of CSR-modified resins to improve CFRPs' performance and provide effective repair solutions for extending the service life of damaged composite structures, rendering them especially suitable for applications demanding high damage tolerance and durability, including aerospace structures, automotive body panels, and energy-absorbing crash components. [ABSTRACT FROM AUTHOR]

Purpose: Congenital diaphragmatic herniae (CDH) may require patch closure in 50% of the cases. We assessed a biologic and composite mesh in a porcine CDH model. Methods: Left sided thoracotomy was performed in 20 pigs. Approximately, 30% of the diaphragm was excised and the patch (Surgisis® or Parietex®) inserted to close this defect. The pigs were killed at 6 months and the diaphragm was harvested for biomechanical and histological assessment. Results: The mean weight of the pigs at surgery and killing were 6.1 kg (4.2–8.4 kg) and 94.1 kg (80–131 kg), respectively. There were two recurrences and three eventrations, all with Surgisis®. There were less dense lung and abdominal adhesions in the Parietex group (P < 0.0001 and 0.025, respectively). The tensile strength of the Surgisis®, the Parietex® groups and controls were similar. There was significantly more muscle in-growth in the Parietex® patch over Surgisis® (p = 0.016). Conclusion: Parietex® and Surgisis® patches at 6 months have a similar tensile strength to normal tissue. All recurrences and eventrations were in the Surgisis® group. Parietex® patches demonstrated more muscle in-growth into the patch compared to Surgisis®. This is the first study utilising Parietex® composite patch in the repair of large diaphragmatic defects in a porcine model. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

IntroductionCongenital diaphragmatic hernia (CDH) repair is an area of active research. Large defects requiring patches have a hernia recurrence rate of up to 50%. We designed a biodegradable polyurethane (PU)-based elastic patch that matches the mechanical properties of native diaphragm muscle. We compared the PU patch to a non-biodegradable Gore-Tex™ (polytetrafluoroethylene) patch.MethodsThe biodegradable polyurethane was synthesized from polycaprolactone, hexadiisocyanate and putrescine, and then processed into fibrous PU patches by electrospinning. Rats underwent 4 mm diaphragmatic hernia (DH) creation via laparotomy followed by immediate repair with Gore-Tex™ (n = 6) or PU (n = 6) patches. Six rats underwent sham laparotomy without DH creation/repair. Diaphragm function was evaluated by fluoroscopy at 1 and 4 weeks. At 4 weeks, animals underwent gross inspection for recurrence and histologic evaluation for inflammatory reaction to the patch materials.ResultsThere were no hernia recurrences in either cohort. Gore-Tex™ had limited diaphragm rise compared to sham at 4 weeks (1.3 mm vs 2.9 mm, p = 0.003), but no difference was found between PU and sham (1.7 mm vs 2.9 mm, p = 0.09). There were no differences between PU and Gore-Tex™ at any time point. Both patches formed an inflammatory capsule, with similar thicknesses between cohorts on the abdominal (Gore-Tex™ 0.07 mm vs. PU 0.13 mm, p = 0.39) and thoracic (Gore-Tex™ 0.3 mm vs. PU 0.6 mm, p = 0.09) sides.ConclusionThe biodegradable PU patch allowed for similar diaphragmatic excursion compared to control animals. There were similar inflammatory responses to both patches. Further work is needed to evaluate long-term functional outcomes and further optimize the properties of the novel PU patch in vitro and in vivo.Level of evidenceLevel II, Prospective Comparative Study.

Objective: This systematic review aims to evaluate current choices in practice and outcomes of biomaterials used in patch repair of congenital diaphragmatic hernia (CDH). Background: Multiple biomaterials, both novel and combinations of preexisting materials are employed in patch repair of large size CDHs. Methods: A literature search was performed across Embase, Medline, Scopus, and Web of Science. Publications that explicitly reported patch repair, material used, and recurrences following CDH repair were selected. Results: Sixty-three papers were included, presenting data on 4595 patients, of which 1803 (39.2%) were managed using 19 types of patches. Goretex® (GTX) (n=1106) was the most frequently employed patch followed by Dualmesh® (n=267), Surgisis® (n=156), Marlex®/GTX® (n=56), Tutoplast dura® (n=40), Dacron® (n=34), Dacron®/GTX® (n=32), Permacol® (n=24), Teflon® (n=24), Surgisis®/GTX® (n=15), Sauvage® Filamentous Fabric (n=13), Marlex® (n=9), Alloderm® (n=8), Silastic® (n=4), Collagen coated Vicryl® mesh (CCVM) (n=1), Mersilene® (n=1), and MatriStem® (n=1) Biomaterials were further subgrouped as: synthetic nonresorbable (SNOR) (n=1458), natural resorbable (NR) (n=241), combined natural and synthetic nonresorbable (NSNOR) (n=103), and combined natural and synthetic resorbable (NSR) (n=1). The overall recurrence rate for patch repair was 16.6% (n=299). For patch types with n>20, recurrence rate was lowest in GTX/Marlex (3.6%), followed by Teflon (4.2%), Dacron (5.6%), Dualmesh (12.4%), GTX (14.8%), Permacol (16.0%), Tutoplast Dura (17.5%), SIS/GTX (26.7%), SIS (34.6%), and Dacron/GTX (37.5%). When analyzed by biomaterial groups, recurrence was highest in NSR (100%), followed by NR (31.5%), NSNOR (17.5%), and SNOR the least (14.0%). Conclusion: In this cohort, over one-third of CDH were closed using patches. To date, 19 patch types/variations have been employed for CDH closure. GTX is the most popular, employed in over 60% of patients; however, excluding smaller cohorts (n<20), GTX/Marlex is associated with the lowest recurrence rate (3.6%). SNOR was the material type least associated with recurrence, while NSR experienced recurrence in every instance. [ABSTRACT FROM AUTHOR]

AbstractThe patch repair is a widely used method for repairing the damaged composite structure, optimizing the repair structure in considering static strength and fatigue life can greatly improve the reliability and safety. However, only static strength and fatigue life are considered during the design or optimization. In this article, the multi-objective optimization of composite laminate repaired by patches in considering static strength and fatigue life was carried out. The models used for predicating static strength and fatigue life were established through finite element method (FEM). Then, the established models were adopted to investigate the effect of repair parameters on static strength and fatigue life, results show that patch radius has the strongest impact on static strength and fatigue life, while the repair thickness and stacking sequence of patch show a greater impact on fatigue life. Based on the above conclusions, Non-dominated Sorting Genetic Algorithm (NSGA-II) was employed to optimize the repair structure. The optimization results show that strength and fatigue life was greatly improved, the repair thickness, and patch volume was greatly reduced, patches that radius is larger than 14 mm can ensure that the repair structure has both higher strength and better fatigue resistance. The proposed optimization method has a good optimization effect for composite laminate repaired by patches. [ABSTRACT FROM AUTHOR]

• Transatrial re-endocardialization (TAR) technique involves suture closure of trabeculation surrounding ventricular septal defects (VSD). • When used in conjunction with traditional patch repair, TAR minimizes the amount of patch material requiring, thereby reducing septal dysfunction. • TAR also allows for superficial suturing which also decreases rate of postoperative conduction block. • TAR is especially beneficial in reducing postoperative complications in "Swiss-cheese" VSD repair. Transatrial re-endocardialization (TAR) is a technique used to complement conventional patch repair of multiple ventricular septal defects (mVSD). To inform operative strategy, pre-operative imaging is supplemented by pre-cardiopulmonary bypass (CPB) intraoperative epicardial echocardiography to understand the size and location of all VSDs. After standard cannulation and arrest, L-shaped right atriotomy is performed and the superior margin of VSDs are marked. Perimembraneous and moderate-large VSDs with insufficient surrounding trabeculae are closed with patch repair. Remaining small muscular VSDs are addressed by TAR, whereby the defect is closed in 2-layers with fine polypropylene suture for superficial re-approximation of adjacent right ventricular trabeculation. Success of repair is evaluated with high-pressure left ventricular injection and pulmonary-systemic flow ratio after CPB is weaned. Adding TAR to the armamentarium of mVSD repair strategies allows for reduction of patch size, thereby decreasing the risk of ventricular septal dyskinesis and heart block. [ABSTRACT FROM AUTHOR]

Thoracoscopic CDH repair is increasingly performed for Type A and small Type B defects that are amenable to primary repair. However, the thoracoscopic approach is controversial for larger defects necessitating a patch due to technical complexity, intraoperative acidosis, and recurrence risk. We aim to compare clinical outcomes between thoracoscopic and open patch repair of Type B/C defects, using a standardized technique. This is a single-center retrospective review of thoracoscopic and open CDH patch repairs January 2017–December 2021. We excluded primary repairs, Type D hernias, repairs on ECMO, recurrent repairs. Various preoperative, intraoperative, and postoperative variables were compared. Primary outcome was recurrence rate. Secondary outcomes included intraoperative pH and pCO 2 , operative time, and complication rates. Twenty-nine patients met inclusion criteria (open = 13, thoracoscopic = 16). The open cohort had lower o/e total fetal lung volume (29 vs 41.2%, p = 0.042), higher preoperative peak inspiratory pressures (24 vs 20 cm H 2 O, p = 0.007), were more frequently Type C defects (92.3 vs 31%, p = 0.002) and had liver "up" in left-sided hernias (46 vs 0%, p < 0.0001). Intraoperatively, median lowest pH and highest pCO 2 did not differ; neither did overall median pH or pCO 2. Operative times were similar (153 vs 194 min, p = 0.113). No difference in recurrence rates was identified, however postoperative complications were higher in the open group. There were no mortalities. Although we demonstrate higher disease severity of patients undergoing open repair, thoracoscopic patch repair for Type B/C defects is safe and effective in patients with favorable physiologic status, alleviating concerns for intraoperative acidosis, operative length, and risk of recurrence. II. [ABSTRACT FROM AUTHOR]

This research showcased the use of leftover trash as a substitute for aggregate in mortar combined with saltwater. The raw waste materials underwent analysis using X-ray fluorescence (XRF) in order to determine the component materials and crystalline phases present. The choice of Portland composite cement (PCC) was made because of its durability in a hostile environment. Seawater is used to combat the water crisis and prevent corrosion, thanks to its exceptional resistance to corrosion. The attributes of mortar were assessed in terms of its fresh characteristics (slump and flow table) as well as its mechanical properties (compressive strength, split tensile strength, flexural strength, density, and shrinkage). The findings indicate that the dried mortar waste is suitable as a patch repair material for a substrate with a strength of 20 MPa, but only when utilized in a maximum quantity of 20% and with a water-to-cement ratio of 0.3. The repaired concrete with a strength of 25 MPa did not need any waste containment and had a maximum water-to-cement ratio (W/C) of 0.3, whether combined with saltwater or tap water. The possible role of the mortar containing the dried waste was to be the species for brick and other non-structural. Additionally, the use of an alternative cementitious substance is suggested to enhance the effectiveness of the patch repair material, particularly when paired with cathodic corrosion protection in damaged concrete

In this study, a high-strength carbon fiber reinforced composite laminate for rail vehicles was machined as a perforated sample and repaired by bonding a patch of the same material. The mechanical response of the repaired laminate to a low-velocity impact with energies of 25J and 30J was investigated through experiments and simulations with variations in patch thickness, size radius, and off-axis angle. The finite element simulation model was established in Abaqus/Explicit. The model integrated the progressive damage model based on the 3D-Hashin failure criterion, which can simulate the intralaminar damage of the fiber and the matrix. The cohesive zone model was used to simulate the delamination damage. According to the finite element analysis results, the mechanism and process of impact damage of the repaired laminates were analyzed. Based on the validated finite element model, the effect of patch size, thickness and off-axis angle on impact response was investigated. Patch radius reduced to 15 mm or thickness reduced to 2.1 mm can still resist low-velocity impacts with an energy of 30 J. Although the off-axis angle of the patch had little effect on the impact response of the repaired laminate, an off-axis angle of 90° was effective in suppressing delamination damage within the patch.

Background: Ventricular septal defect is a hole or multiple holes in the interventricular septum. Hearts with these primary defects may have minor coexisting morphologic abnormalities, or may be part of another major cardiovascular anomaly. Peri membranous ventricular septal defects are among the most common cardiac malformations and constitute 80% of these defects. Ventricular septal defects may be small, moderate or large size. Material and Methods: The study was conducted in the Department of Cardiovascular and Thoracic Surgery on patients operated for ventricular septal defects. Results: A total of 9 patients, mostly in second decade, irrespective of age, sex, clinical presentation and surgical outcome were included in the study. Male patients were more. Tachypnoea was the presenting symptom, and pansystolic murmur common clinical observation. Two-dimensional echocardiography was the investigation of choice, and around 80% had peri membranous type of defect. All the patients were operated under cardiopulmonary bypass, patch repair was common surgical procedure. There was no mortality. Conclusion: Early and precise diagnosis, followed by definitive management (Device closure / Open Surgical repair) gives excellent results. [ABSTRACT FROM AUTHOR]

Adhesively bonded steel patches present a novel approach to strengthen fatigue cracked steel bridges or similar structures. After the repair, the new weld is covered with an adhesively bonded steel patch, redistributing parts of the load and reducing the overall stress in the repaired structure. Unfortunately, this covers the weld permanently and therefore any form of direct, visual inspection is no longer possible. Hence arises the demand for a technical solution to reliably determine the condition of the repaired weld and its reinforcement. Fibre optic sensors using Rayleigh backscatter offer a spatial distributed strain measurement from which a deformation profile can be generated. This deformation profile allows to determine the load distribution between patch and structure and can be used to identify possible changes in the load distribution which can represent a change in the mechanical properties and therefore a possible defect. Having not only the information about the absolute value of the strain but also its distribution, the expected damage can be located and measured. The deformation profile also allows to separate different forms of failure for example a broken weld, adhesive failure within the patched area or sub surface migrating corrosion. [ABSTRACT FROM AUTHOR]

The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate. This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates. The specimens of [0°/45°/45°/0°] laminates were repaired with adhesively bonded two-ply [45°]2 external patches. Three different cases of drilled specimens were produced with different hole arrangements viz. specimens with single central hole (SH), with two holes aligned along the longitudinal axis (LH) and with two holes along transverse axis (TH). The two-hole specimens were repaired with two different types, i.e. single large patches (SP) and with the two smaller patches (DP) of combined bonding area equal to the single large patches. Digital image correlation (DIC) was employed to capture strain contours. The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes. The TH repaired specimen exhibit significant load recovery (SP-32.75%, DP-34.62%) while the LH specimens result in very marginal (SP- 6.11%, DP-4.10%) recovery compared to their drilled case. The TH specimen failed by crack growing through both the holes beneath the patch, while the LH specimens failed by the failure through only one hole. The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery.

An unsaturated polyester resin (UPR) mortar was applied to repair the damage to the tension zone's one-way reinforced concrete (RC) slabs. The load carrying capacity of the patched RC slab is of interest to justify the effectiveness of the repair. The Yield Line Theory (YLT) may be used to estimate the load carrying capacity of patched RC slabs under concentrated load. The results of the YLT are compared with the experimental results to evaluate the validity of the YLT method. The results confirm that patching alters the yield line formation, mainly when the concentrated load is applied close to the patching zone. Subsequently, the YLT method provides a higher load carrying capacity estimation deviation for slabs with a loading point near the patching zone. On the other hand, the YLT method estimates load carrying capacity accurately when the loading point is away from the patching zone.

Patch‐repaired plain woven composite structures were exposed to internal damage caused by impact during service, which reduced mechanical properties. A multi‐scale modeling strategy was proposed to study the impact resistance characteristics of patch‐repaired plain woven carbon‐fiber‐reinforced‐polymer (CFRP) laminates. The micro representative volume element (RVE) was extracted from the yarn; a local homogenization method was used to obtain the equivalent cross‐ply laminate (ECPL) cells corresponding to the mesoscale RVE. The finite element model (FEM) of patch‐repaired plain woven laminate was established by extending the ECPL cells. The FEM was checked by the low‐velocity impact (LVI) tests, and the impact parameter errors were within 10%. Furthermore, impact resistance of repaired specimens under different impact conditions (e.g., the impact energy was 3 ~ 20 J) was studied. Finally, patch parameters (patch thickness, patch size, off‐axis angle) of the repaired specimen were optimized by multi‐objective optimization based on the surrogate model and response surface method (RSM). After multi‐objective function optimization, the optimal patch parameter configuration (the thickness of the patch was 0.87 mm, the diameter was 66 mm, and the off‐axis angle was 44.2°) reduced the absorbed energy value of the repaired specimen from 4.9089 to 4.1640 J, and the delamination area of the repaired specimen from 605 to 280 mm2. All the results provide a reference for patch repair of plain woven composites. [ABSTRACT FROM AUTHOR]

Thin panels of aluminium alloy 6061-T6 with a centre pre-crack were repaired with a one-sided asymmetrical CFRP patch through co-curing of epoxy at the room temperature to have minimal residual stresses. The specimens were tested with a tension-tension fatigue load. The numerical simulation as well as the experiments showed that the fatigue life was improved considerably with the increasing patch length when tested at room temperature. In the asymmetrical repair with a single patch, a bending moment was induced whose magnitude decreased with the increasing patch length, resulting into longer fatigue life. The specimens failed through the growth of the pre-crack in the skin. However, the crack in the skin did not grow in case of the specimen with the longest patch length and the failure occurred at substantially higher number of fatigue cycles through a different mechanism in the bare portion of the aluminium alloy skin. Experiments were also conducted at the elevated temperature of 80°C. Thermal compressive stresses were developed in the aluminium alloy panel due to the vast difference in the coefficient of thermal expansion of the aluminium alloy and the CFRP patch. Consequently, the stress intensity factor of the crack in the aluminium panel was reduced considerably, resulting into the increase of the fatigue failure life significantly. [ABSTRACT FROM AUTHOR]

In this study, a finite element model was developed to analyze the mechanical behavior of repairing aluminum 2024-T3 structures subjected to complex shear-shear loads using composite patch repair techniques. The study aimed to investigate the effect of different patch sequences on the mechanical behavior of the repaired structure, including the orientation of the fiber patch, to improve durability under complex shear-shear loading conditions. The study demonstrated that the FEM approach is a robust and precise method for optimizing patch repair and studying the effect of mechanical loads on patch repair effectiveness for aluminum 2024-T3 structures. [ABSTRACT FROM AUTHOR]

Objective Our systematic review aims to compare recurrence rates and complications of biological versus synthetic patches for the repair of congenital diaphragmatic herniae. Methods Studies from January 1, 1980 to April 25, 2020, with patients under the age of 16 years and with a minimum 6-month follow-up, were included from MEDLINE, Embase, and Cochrane databases. Funnel plots for recurrence rates were constructed for biological and synthetic patches. Subgroup analysis was performed for recurrence rate at the 1-year time-point and data were gathered on individual adverse events from relevant studies. Results A total of 47 studies with 986 patients (226 biological, 760 synthetic) were included. Funnel plot analysis determined overall recurrence rates of 16.7% for synthetic and 30.3% for biological patches. Subgroup analysis of 493 and 146 patients with synthetic and biological patches, respectively, showed recurrence rates of 9.9 and 26%, respectively. The most commonly used patch types—PTFE (polytetrafluoroethylene) and SIS (small intestinal submucosa)—had 11.5 and 33.3% recurrence, respectively. Adhesive bowel obstruction rates ranged from 4 to 29% in studies that systematically reported it for synthetic, and 7 to 35% for biological patches. Gastroesophageal reflux rates ranged from 25 to 48% in studies that systematically reported it for synthetic, and 21 to 42% for biological patches. Pectus deformity rates were reported as high as 80% for synthetic patches. Conclusion Biological patches appear to have higher recurrence rates than synthetic patches, while skeletal deformities are associated more commonly with synthetic patches. Results of biological patches are mainly using SIS and this may overestimate complications of current superior biological patches. [ABSTRACT FROM AUTHOR]

Renal artery aneurysms are rare. Indications for management include size > 3 cm, female gender within childbearing age, pain, hematuria, medically refractory hypertension, thromboembolism, dissection, and rupture. Management options include endovascular, open repair, and ex vivo approaches. A 43-year-old female with a history of polycystic kidney disease, solitary kidney, and uncontrolled hypertension was found to have a proximal large renal aneurysm on imaging. The patient underwent an in situ open aneurysm resection, temporary shunt insertion, and patch repair with good postoperative outcomes. Whereas previous studies showed the success of ex vivo repair and autotransplantation in large aneurysms with solitary kidneys, our case demonstrated that in situ open repair and patch with the use of a temporary shunt is a feasible and effective option. In a patient with a solitary kidney and large proximal renal artery aneurysm, an in situ open approach and patch repair with shunt insertion should be considered. [ABSTRACT FROM AUTHOR]

The presence of a geometric discontinuity such as a crack or a notch can cause the failure of a structure during its use. Under various mechanical or thermal stresses, a high concentration of stresses can take place at the level of these discontinuities, which in most cases will lead to the total failure of the structure. The service life of these structures can be improved with the use of the repair technique by bonding a composite patch. This technique is of significant interest in several fields, especially with the use of composite materials. This technique is widely used in aeronautics and ensures a long life of damaged structures. Current research aims to optimize the shape size and fiber's nature of this composite patch in order to ensure good load transfer by reducing the stresses in the damaged area. In this work, a finite element method is used to analysis the effect of the shape of the patch on the global response of a 2024-T3 aluminum structure in the presence of a central circular notch. The composite patch is of the carbon/epoxy type bonded through an A-140 Adekit type adhesive on the damaged part of the plate. The analysis consists in determining the force-displacement curves of the repaired structure by using the combination of the two techniques, XFEM for the damage of the aluminum plate 2024-T3 by the automatic creation of the crack and CZM for the analysis of the adhesive debonding. The analysis takes into account the damage in the plate and in the adhesive. However, for the composite patch, and since there will be no damage, we have just analyzed the effect of its shape and essentially the shape of its edges on the load transfer and consequently on the resistance of the structure under loading in tension. Two main patch shapes have been highlighted, namely the square and circular shape. The results show clearly that the shape of the patch�s edges has an impact on the stresses reduction in the plate and subsequently ensures good resistance in terms of force-displacement curve and consequently delays the peeling of the adhesive

Aerolysin family pore-forming toxins damage the membrane, but membrane repair responses used to resist them, if any, remain controversial. Four proposed membrane repair mechanisms include toxin removal by caveolar endocytosis, clogging by annexins, microvesicle shedding catalyzed by MEK, and patch repair. Which repair mechanism aerolysin triggers is unknown. Membrane repair requires Ca2+, but it is controversial ifCa2+ flux is triggered by aerolysin. Here, we determined Ca2+ influx and repair mechanisms activated by aerolysin. In contrast to what is seen with cholesterol-dependent cytolysins (CDCs), removal of extracellular Ca2+ protected cells from aerolysin. Aerolysin triggered sustained Ca2+ influx. Intracellular Ca2+ chelation increased cell death, indicating that Ca2+-dependent repair pathways were triggered. Caveolar endocytosis failed to protect cells from aerolysin or CDCs. MEK-dependent repair did not protect against aerolysin. Aerolysin triggered slower annexin A6 membrane recruitment compared to CDCs. In contrast to what is seen with CDCs, expression of the patch repair protein dysferlin protected cells from aerolysin. We propose aerolysin triggers a Ca2+-dependent death mechanism that obscures repair, and the primary repair mechanism used to resist aerolysin is patch repair. We conclude that different classes of bacterial toxins trigger distinct repair mechanisms. [ABSTRACT FROM AUTHOR]

The impact responses of a patch-repaired carbon-fiber-reinforced polymer (CFRP) specimen under double impacts were compared to study the damage interference mechanism through the combination of experiment and numerical analysis. A three-dimensional finite element model (FEM) with iterative loading based on continuous damage mechanics (CDM) and a cohesive zone model (CZM) was employed to simulate the double-impacts testing with an improved movable fixture at an impact distance of 0 mm–50 mm. The influence of impact distance and impact energy on the damage interference was explored by mechanical curves and delamination damage diagrams of the repaired laminates. When impactors fell within the range of the patch with an impact distance of 0 mm–25 mm at a low level of impact energy, delamination damage of the parent plate caused by the two impacts overlapped, resulting in damage interference. With the continuing increase in impact distance, the damage interference gradually disappeared. When impactors fell on the edge of the patch, the damage area caused by the first impact on the left half of the adhesive film gradually enlarged, and as the impact energy increased from 5 J to 12.5 J, the damage interference caused by the first impact on the second impact was gradually enhanced. [ABSTRACT FROM AUTHOR]

Damage occurring on a reinforced concrete beam (e.g. spalling) can reduce beam’s capacity to withstand external loads. The damage becomes more critical if it is occurred in the shear span since it may lead to shear failure. Patching to the damage zone by suitable patch repair material could be the best option in restoring the shear capacity of the beam. This research investigates the shear recovery of patched reinforced concrete beams with web reinforcement. The patching material used is unsaturated polyester resin mortar. The shear recovery is assessed on the basis of the patched beam’s behavior under flexure-shear load in comparison with those of normal beams. The behavior observed include cracking failure mode, strains of the reinforcements, and load-deflection behavior. The results indicate that the UPR mortar is capable to restore the strength of the damage reinforced concrete beam. The characteristic of UPR mortar (low elastic modulus and high strength) can be the origin of the overall behavior of the patched reinforced concrete beams.

Objectives Treatment of destructive endocarditis with abscess formation is a surgical challenge and associated with significant morbidity and mortality. A root replacement is often performed in case of an annular abscess. This retrospective study was designed to assess the long-term outcome of extensive debridement and patch reconstruction as an alternative approach. Methods Between November 2007 and November 2016, a selected group of 79 patients (29.6% of all surgical endocarditis cases) with native valve endocarditis (NVE, 53.2%) or prosthetic valve endocarditis (PVE, 46.8%) valve endocarditis underwent surgical therapy with extensive annular debridement and patch reconstruction. Their postoperative course, freedom from recurrent endocarditis, and survival at 1, 5, and 7 years were evaluated. Results About two-thirds of patients were in a stable condition, one-third of patients were in a critical state. The median logistic EuroSCORE I was 17%. Infected tissue was removed, and defect closure was performed, either with autologous pericardium for small defects, or with bovine pericardium for larger defects. Overall, in-hospital mortality was 11.3% (NVE: 9.7%, PVE: 13.2%; p = 0.412). In single valve endocarditis survival at 1, 5, and 7 years was 81, 72, 72%, respectively for NVE, and 80, 57, 57%, respectively for PVE (p = 0.589), whereas in multiple valve endocarditis survival at 1, 5, and 7 years was 82, 82, 82% for NVE, and 61, 61, and 31%, respectively for PVE (p = 0.132). Confirmed late reinfection was very low. Conclusion Surgical treatment of destructive endocarditis with abscess formation using patch repair techniques offers acceptable early and long-term results. The relapse rate was low. PVE and involvement of multiple valves were associated with worse outcomes. [ABSTRACT FROM AUTHOR]

An unsaturated polyester resin (UPR) mortar was applied to repair the damage to the tension zone's one-way reinforced concrete (RC) slabs. The load carrying capacity of the patched RC slab is of interest to justify the effectiveness of the repair. The Yield Line Theory (YLT) may be used to estimate the load carrying capacity of patched RC slabs under concentrated load. The results of the YLT are compared with the experimental results to evaluate the validity of the YLT method. The results confirm that patching alters the yield line formation, mainly when the concentrated load is applied close to the patching zone. Subsequently, the YLT method provides a higher load carrying capacity estimation deviation for slabs with a loading point near the patching zone. On the other hand, the YLT method estimates load carrying capacity accurately when the loading point is away from the patching zone. [ABSTRACT FROM AUTHOR]

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Isolated tricuspid valve endocarditis accounts for only 5 to 10 percent of infective endocarditis cases globally. Numerous surgical procedures ranging from simple vegetectomy, creation of neoleaflets or complete replacement by a prosthetic valve have been described. We aimed to evaluate our experience in surgical management of this entity and to formulate an approach for timing, appropriateness and extent of surgery. Patients operated on semi elective/emergency basis had adverse outcome with residual regurgitation and had longer ICU stay. Also, patients who required excision of leaflet and creation of neoleaflets had a higher incidence of regurgitation. This suggests that maximal preservation of native valve lessens the incidence of residual regurgitation. Simple vegetectomy and patch repair of the residual defect offers the best outcome.

This study investigates assessment of the barely visible impact damage (BVID) caused by low‐velocity impact (LVI) in single‐sided patch‐repaired orthotropic carbon fiber‐reinforced polymer (CFRP) laminates using experimental and numerical nonlinear Lamb wave‐mixing techniques. An accurate finite element method (FEM) approach consisting of three analysis steps of LVI, vibration damping, and nonlinear ultrasonic mixing detection is proposed to predict the relationship between LVI damage and nonlinear Lamb wave‐mixing propagation. The LVI step in the FEM simulation is verified by drop‐weight impact tests, and the nonlinear Lamb wave‐mixing detection step in FEM is verified by comparing with the RITEC RAM‐5000 SNAP nonlinear mixing detection system. The BVID of patch‐repaired specimens is assessed with mixing relative acoustic nonlinearity parameters (MRANPs). CFRP laminates repaired with various external patch parameters of different sizes, numbers of layers and stacking sequences are evaluated by the FEM approach. Finally, an optimized patch design in which the MRANPs are the smallest is determined. Therefore, the CFRP laminate containing a hole is recommended to be repaired with a circular three‐layer patch with a radius of 2.5 r and a stacking sequence of [90/90/90]. [ABSTRACT FROM AUTHOR]

The presence of a geometric discontinuity such as a crack or a notch can cause the failure of a structure during its use. Under various mechanical or thermal stresses, a high concentration of stresses can take place at the level of these discontinuities, which in most cases will lead to the total failure of the structure. The service life of these structures can be improved with the use of the repair technique by bonding a composite patch. This technique is of significant interest in several fields, especially with the use of composite materials. This technique is widely used in aeronautics and ensures a long life of damaged structures. Current research aims to optimize the shape size and fiber's nature of this composite patch in order to ensure good load transfer by reducing the stresses in the damaged area. In this work, a finite element method is used to analysis the effect of the shape of the patch on the global response of a 2024-T3 aluminum structure in the presence of a central circular notch. The composite patch is of the carbon/epoxy type bonded through an A-140 Adekit type adhesive on the damaged part of the plate. The analysis consists in determining the force-displacement curves of the repaired structure by using the combination of the two techniques, XFEM for the damage of the aluminum plate 2024-T3 by the automatic creation of the crack and CZM for the analysis of the adhesive debonding. The analysis takes into account the damage in the plate and in the adhesive. However, for the composite patch, and since there will be no damage, we have just analyzed the effect of its shape and essentially the shape of its edges on the load transfer and consequently on the resistance of the structure under loading in tension. Two main patch shapes have been highlighted, namely the square and circular shape. The results show clearly that the shape of the patch's edges has an impact on the stresses reduction in the plate and subsequently ensures good resistance in terms of force-displacement curve and consequently delays the peeling of the adhesive. [ABSTRACT FROM AUTHOR]

The presence of a geometric discontinuity such as a crack or a notch can cause the failure of a structure during its use. Under various mechanical or thermal stresses, a high concentration of stresses can take place at the level of these discontinuities, which in most cases will lead to the total failure of the structure. The service life of these structures can be improved with the use of the repair technique by bonding a composite patch. This technique is of significant interest in several fields, especially with the use of composite materials. This technique is widely used in aeronautics and ensures a long life of damaged structures. Current research aims to optimize the shape size and fiber's nature of this composite patch in order to ensure good load transfer by reducing the stresses in the damaged area. In this work, a finite element method is used to analysis the effect of the shape of the patch on the global response of a 2024-T3 aluminum structure in the presence of a central circular notch. The composite patch is of the carbon/epoxy type bonded through an A-140 Adekit type adhesive on the damaged part of the plate. The analysis consists in determining the force-displacement curves of the repaired structure by using the combination of the two techniques, XFEM for the damage of the aluminum plate 2024-T3 by the automatic creation of the crack and CZM for the analysis of the adhesive debonding. The analysis takes into account the damage in the plate and in the adhesive. However, for the composite patch, and since there will be no damage, we have just analyzed the effect of its shape and essentially the shape of its edges on the load transfer and consequently on the resistance of the structure under loading in tension. Two main patch shapes have been highlighted, namely the square and circular shape. The results show clearly that the shape of the patch’s edges has an impact on the stresses reduction in the plate and subsequently ensures good resistance in terms of force-displacement curve and consequently delays the peeling of the adhesive.

A common form of damage encountered in marine structures is the accumulation of corrosion in susceptible areas, which leads to material wastage. As a result, the structural strength of the members affected is compromised, endangering their safe operation in design loads. Consequently, structural instabilities may occur, such as buckling due to compressive or/and shear loads. An alternative repair practice for preventing such phenomena, approved for secondary load-carrying members, is the application of composite patches to the damaged area. In this preliminary study, this technique is examined in the scope of developing a framework that can be used to find the optimal solution for restoring the buckling strength of a corroded plate. The methods used to achieve this are based on finite element analysis (FEA) and design of experiments (DoE) to statistically analyze the aforementioned numerical calculations. By introducing the composite patch’s percentage coverage of its metal substrate and number of plies as design parameters, a response surface is generated with respect to the obtained factor of safety (regarding its reference uncorroded buckling strength). This list of data points is then evaluated, and an acceptable surface/list of design parameters’ combinations is generated.

Chest wall tumor resection can result in a large defect that can pose a challenge in reconstruction in restoring chest wall contour, maintaining respiratory mechanics, and improving cosmesis. Titanium plates were first introduced for treating a traumatic flail chest, which yielded promising results in restoring chest wall stability. Subsequently, the applications of titanium plates in chest wall reconstruction surgery were demonstrated in case reports and series. Our center has adopted this technique for a decade, and patients are actively followed up after operation. Here, we retrospectively analyze our 10-year experience of using titanium plates and other reconstruction approaches for chest wall reconstruction, in terms of clinical outcomes, complications, and reasons for reoperation to determine long-term safety and efficacy. Thirty-eight patients who underwent chest wall resection and reconstruction surgery were identified. Of these, 11 had titanium plate insertion, 11 had patch repair or flap reconstruction, and the remaining 16 had primary closure of defects. Chest wall reconstruction using titanium plate(s) and patch repair (with or without flap reconstruction) was associated with larger chest wall defects and more sternal resections than primary closure. Subgroup analysis also showed that reconstruction by the titanium plate technique was associated with larger chest wall defects than patch repair or flap reconstruction [286.80 cm2 vs. 140.91 cm2 (p = 0.083)]. There was no 30-day hospital mortality. Post-operative arrhythmia was more commonly seen following chest wall reconstruction compared with primary closure (p = 0.041). Furthermore, more wound infections were detected following the use of titanium plate reconstruction compared with the patch repair (with or without flap reconstruction) approach (p = 0.027). In conclusion, the titanium plate system is a safe, effective, and robust approach for chest wall reconstruction surgery, especially in tackling larger defect sizes.

Abstract Background Symptomatic Bochdalek hernias are found mainly in infants in respiratory distress and occur rarely in adults. Case presentation We report a rare case of Bochdalek hernia associated with developmental abnormalities in an adult who exhibited acute chest pain and dyspnea on exertion. Conclusions This case highlights the importance of the differential diagnosis of acute left-sided chest pain and antenatal examination.

This work involves an experimental investigation of the external patch repaired woven carbon fiber‐reinforced polymer laminates under load controlled constant amplitude compressive fatigue loading. The specimens of parent laminates with stacking sequence [0/45]s and [45/0]s were both repaired with two types of precured patches viz. [0]2 and [45]2 representing high stiff and low‐stiff cases. Digital image correlation and acoustic emission were employed to obtain the insight to the development of distinctive failure modes. The observations during the tests reveal a slow increase in the displacement for most part of the life followed by a rapid increase in the displacement signifying the failure due to fatigue. The examination of failed specimens reveal failure through hole for drilled (with hole) specimens compared to failure away from repaired zone indicating the significant reinforcement provided by external patch repair under cyclic loading. From life aspect, the drilled specimens possess a significantly lesser life (zero to few hundred cycles) compared to the patch repaired and pristine specimens (of order of few thousand cycles) highlighting the suitability of the external patch repair to restore the fatigue performance under compressive loading. [ABSTRACT FROM AUTHOR]

The aim of this study is to compare outcome between small intestinal submucosal (SIS) and polytetrafluoroethylene (PTFE) patches in patients with congenital diaphragmatic hernia (CDH) with large muscular defects. We performed a retrospective review of prospectively collected data of patients who underwent CDH repair from January 2011 to June 2019, with a minimum follow-up of 1 year. Data were collected regarding length of stay (LOS), mortality and recurrence. Kaplan-Meier analyses was used. In the study period, 195 patients with CDH were admitted, 176 underwent surgical repair and 19 died before surgery. Sixty-two (35%) required a patch. Over the last 5 years, our institution transitioned from the use of all SIS to all PTFE. SIS was used in 18 cases and PTFE in 25. Overall survival rate was 89% (174/195). There was no significant difference regarding LOS and mortality. Nine patients (50%) of SIS and 1 (4%) of PTFE repairs recurred (P < 0.01; log-rank test P < 0.01), with a time course of recurrence of 18 (SD = 13) and 8 months, respectively. Median follow-up was 60 months (SD: 23) for the SIS group and 26 (SD: 10) for the PTFE group. A significant lower recurrence was found using PTFE patches instead of SIS for the repair of large CDH. Level 3. Retrospective comparative study. [ABSTRACT FROM AUTHOR]

Through this study, a numerical simulation based on 3D in order to investigate the effect of crack-front shape on the stress intensity factor and fatigue crack growth behavior of center cracked aluminum plate repaired asymmetrically with bonded composite patch. Consequently, skew degree it is a significant effect on stress intensity factor (SIF) distribution along the crack front in thick panels more than in thin panels. Moreover, fatigue life was calculated using different averaged stress intensity factor of patched panel determined from uniform crack front model and skew crack front model obtained from FEM and when comparing fatigue life values obtained from the finite element model with experimental values were shown a good agreement.

Aortobronchial fistula is a rare cause of repeated hemoptysis and a potentially fatal condition if left untreated. We present the case of a 40-year-old man with repeated hemoptysis, excessive cough, and epistaxis ongoing for several days after SARS-CoV-2 pneumonia diagnosis. The patient had a history of patch aortoplasty for aortic coarctation and aortic valve replacement with a mechanical valve for aortic insufficiency due to bicuspid aortic valve at the age of 24. Computed tomography scan performed at presentation revealed a severely dilated ascending aorta, a thoracic aorta pseudoaneurysm at the site of the former coarctation, an aortobronchial fistula suggested by the thickened left lower lobe apical segmental bronchus in contact with the pseudoaneurysm and signs of alveolar hemorrhage in the respective segment. The patient was treated with thoracic endovascular aneurysm repair (TEVAR) after prior hemi-aortic arch debranching and transposition of the left common carotid artery and subclavian artery through a closed-chest surgical approach. Our case report together with a systematic review of the literature highlight the importance of both considering an aortobronchial fistula in the differential diagnosis of hemoptysis in patients with prior history of thoracic aorta surgical intervention, regardless of associated pathology, and of taking into account endovascular and hybrid techniques as an alternative to open surgical repair, which carries a high risk of morbidity and mortality.

In this study, the impact response, damage accumulation, interlaminar and intralaminar energy dissipation distributions of patch-repaired carbon fiber reinforced polymer (CFRP) laminates under repeated impacts were studied by combining experimental and numerical methods. A three-dimensional finite element model (FEM) based on continuum damage mechanics (CDM) and cohesive zone model (CZM) was performed using ABAQUS/Explicit to simulate the impact experiments (at impact energy of 10 J ~ 20 J). The influence of impact energy (5 J ~ 15 J) on damage accumulation, interlaminar and intralaminar energy dissipation was explored by numerical calculations. It was found that the sudden drop of the force-time curve was an important signal of serious internal damage of the patch; at impact energy of 5 J ~ 12.5 J, the impact parameters such as impact time, peak force and maximum deflection increased with the increase of impact times; at impact energy of 5 J ~ 12.5 J, the delamination damage after the first impact and the corresponding interlaminar energy dissipation increased slightly with the increase of impact times; the delamination damage can be used as an important factor to reflect the damage accumulation degree of patch-repaired laminates under repeated impacts.