Volume Defects Research Articles

Mitigating aging infrastructure risks: An optimized epoxy resin system for water supply pipeline rehabilitation

Urban water supply networks are crucial for ensuring the delivery of safe drinking water to urban populations; however, the aging infrastructure in these systems has led to a rising incidence of leaks and frequent pipeline failures, posing serious risks. Traditional repair approaches encounter limitations in terms of efficiency, durability, and environmental safety, particularly when employed in potable water pipelines. To address these challenges, we developed a novel multi-component amine-cured epoxy resin system specifically optimized for in-situ curing under ambient conditions. This study comprehensively examines the mechanical properties, water absorption behavior, and curing kinetics of this resin system, formulated to reduce volatile organic compound emissions while enhancing durability under prolonged water exposure. Experimental findings demonstrate that the E2 formulation exhibited superior tensile strength, flexural properties, and fracture toughness relative to other formulations, with a two-stage water absorption model accurately predicting resin behavior in moisture-laden environments. Moreover, finite element modeling and laboratory testing confirmed the influence of bubble defects on mechanical performance, and a negative pressure defoaming technique effectively reduced defect volume, resulting in a 17.6% improvement in tensile strength. Collectively, this research advances the practical application of rapid-curing resins, offering a resilient, safe, and sustainable solution for the rehabilitation of aging water pipeline networks.

Minimally invasive balloon-reduction of acute Hill-Sachs-lesions and impression fractures after shoulder dislocation – an experimental approach

The shoulder is the joint most often affected by dislocations. It is known that bony defects of the glenoid and/or humerus can lead to recurrent dislocations even after arthroscopic shoulder stabilization. To prevent recurrent instability, it appears reasonable to reduce fresh and larger Hill-Sachs lesions (off-track lesions). In spine surgery, balloon kyphoplasty is widely used for fracture reduction. The aim of this study was to determine whether the balloon dilatation procedure is transferable to the humeral head and under which conditions it can be successful. In this biomechanical proof-of-concept study, a preformed "impression stamp" was used to create standardized Hill-Sachs impressions (Calandra grade III lesion) on 13 human humeral specimens. A kyphoplasty balloon was then placed intraosseously and close to the defect using a special monolateral trocar and the defect was reduced by balloon dilatation. CT imaging was performed on the native specimens, after defect placement and after reduction. Both the defect size and the extent of reduction were measured radiologically, as well as the bone density. Also, the pressure and volume necessary for reduction were measured. 13 proximal humerus specimens were examined. The mean age of the 7 body donors (3 female) was 85 years (SD ±8.1). The average bone density was 49.0 mg/ml (SD ±26.9) and therefore defined as osteoporotic. The average defect depth (difference to native, measured from a best-fit circle) was 4.1 mm (SD ±1.4), corresponding to an average defect volume of 1203 mm³ (SD ±949). After balloon dilatation, the average achieved reduction (difference to the defect) was 4.3 mm (SD ±1.9) or 1223 mm³ (SD ±1059). This results in an average difference from native to reduced of -0,2 mm (SD ±0.5) or 20 mm³ (SD ±212) and represents no significant difference compared to baseline values (p = 0.90 or p = 0,75, respective), but a slight overreduction in the volumetric measurements. In all humeral specimens, a reduction of at least 2.6 mm or 221 mm³ compared to the defect situation was achieved. An average volume of 3.4 ml (SD ±1,1) and pressure of 271 psi (SD ±81) were required for reduction. The present results demonstrate, that minimally invasive balloon reposition of large acute Hill-Sachs lesions appears methodologically feasible. The required pressure for reduction seems to be higher compared to previous studies. Further studies are necessary for the development of this technique and its reproducible translation into clinical practice.

Computational simulation of alternating current (AC) impedance of hardened cement mortar

The present study proposes a novel methodology for simulating the AC impedance of hardened cement mortar, through the technology of micro computed tomography based finite element analysis (μCT-based FEA). Three-dimensional (3D) physical meso-scale structure of hardened cement mortar is first segmented into multicomponent phases of air void, cement paste, sand aggregate, and interfacial transition zone (ITZ) considered with different thicknesses. Then, the real structure of mortar after discretization is subjected to current harmonic perturbations to acquire its AC impedance spectra. Compared to traditional impedance measurement, the proposed simulation approach avoids the influence of external electrode and hence improves the characterization of cementitious electrochemical system in its true state. The simulated complex impedance presents a depressed high-frequency loop and varies with the increasing ITZ thickness in the range of 26.6 to 106.4 μm. The numerical impedance plots are fitted to a theoretical equivalent circuit model of Rs(RctQ) consisting of bulk ionic resistance (Rs), charge transfer resistance (Rct) at the solid/liquid interface, and non-Debye capacitance (Q). The changes in mesostructure of cement mortar with the thickened ITZs can be captured by a linear reduction of Rs, a non-linear decrease of Q, and a limited increase of Rct. Based on the electrochemical impedance modelling, the study establishes the mathematical relationship between the defect's volume (air voids plus ITZ) and the model's parameters (Rs or Rct) for prediction of material deterioration.

Research on Typical Decay-like Fracture Defects of Composite Insulators Based on Electro-Thermal Coupling

In response to the typical decay and fracture defects of composite insulators, a three-dimensional electrically and thermally coupled simulation physical model was constructed based on the finite element method, and the local electric field distortion and temperature rise were analyzed. The study confirms that the insulator interface’s axial electric and thermal fields show a U-shaped curve; the interface field strength is the largest. There is an electric field gradient difference between the mandrel and the sheath, and the thermal field is concentrated at the mandrel and the interface. The field strength at the edge of the defect is the largest, the aberrant electric field at the defect shows a sawtooth shape, and the temperature rise is concentrated in the defect area. The degradation is fast in the air gap, the etching hole diameter direction, and the carbonation channel axial direction. The larger the defect volume, the larger the aberration in the electric field and temperature rise. Water vapor air gaps, breakdown holes, and carbonized channels have the most pronounced electric field and temperature changes. The functional relationship between electric field aberration, temperature rise, and defect volume is established. The results provide a basis for the protection of insulator decay-like fracture.

The accuracy and efficiency of design and development of 3D printed integral anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip

Objective: To compare the accuracy and efficiency between the model development method and the software development method, which design and develop 3D printed integral anatomical acetabular prosthesis to be used in total hip arthroplasty(THA) for patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip(DDH). Methods: Fifteen patients with end-stage hip osteoarthritis due to Crowe type Ⅱ and Ⅲ DDH who underwent THA in the Orthopedics Department of the First Affiliated Hospital of Bengbu Medical College between January 2015 and June 2023 were selected in this study retrospectively. There were 1 male (1 hip) and 14 females (17 hips) with a mean age of (55.1±9.1) years. There were 12 hips with Crowe type Ⅱ, 6 hips with Crowe type Ⅲ. The preoperative pelvis three-dimensional CT data in those patients were used to design integral anatomical acetabular prosthesis. The model development group used 3D printing technology to print life-size pelvis models. The acetabulum was reamed and the acetabulum cup was inserted into the socket according to conventional THA procedures. The bone defect above the acetabulum cup was filled with bone wax. The Mimics and 3-matic software were used to simulate the THA procedures, design and install the integrated anatomical acetabular prosthesis in the software development group. The operation time, the size of the acetabular cup, the volume and surface area of the acetabulum bone defect, the acetabular cup's inclination and anteversion, the horizontal distance and the vertical distance of hip rotation center were compared between the two methods. Results: The study in the two groups were all based on the data of 18 hips in the 15 patients. The horizontal and vertical distances of rotation center in the model development group and software development group was (32.08±1.80) mm, (32.17±2.40) mm and (14.36±1.53) mm, (15.11±1.45) mm, respectively (both P>0.05). The cup size in model development group was (48.56±1.15)mm, and it was (48.77±1.22) mm in the software group (P=0.160). The anteversion and inclination of the acetabular cup in the model and software groups were 23.79°±6.31°, 30.49°±11.03° and 15.17°±0.52°, 40.24°±0.58°, respectively (both P<0.01). The volume and surface area of the acetabulum bone defect in the model development group was (5.06±2.86) mm3 and (8.31±2.21) mm2, respectively, while it was (4.01±2.56)mm3 and (6.83±2.71) mm2, respectively, in the software development group (both P<0.05). The work time in the model development group was (24.43±0.68) h and (0.47±0.12) h in the software development group, respectively (P<0.001). Conclusion: Compared with the 3D printing model development method, the application of Mimics and 3-matic software to design and develop integrated anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ DDH show advantages of convenience, high efficiency and more accuracy.

A comparison of wire-feed additive manufacturing and hybrid additive/subtractive manufacturing of high nitrogen steel

High nitrogen austenitic stainless steel, referred to as high nitrogen steel (HNS), has been widely studied and applied because of its excellent properties such as high strength, good plasticity and toughness. However, its high nitrogen content makes the deposition metal face problems such as nitrogen porosity, nitrogen escape and loss when it is processed by additive manufacturing (AM), which has a negative impact on the mechanical properties. Two thin-walled specimens without obvious defects were obtained by wire-feed AM and hybrid additive/subtractive manufacturing (HASM) using the self-made HNS wire with 0.7 wt.% N, respectively. The porosity, microstructures and tensile properties of thin-walled specimens were compared. The porosity of the two specimens was tested by an industrial computed tomography (CT) system. The defect volume ratio and the diameter of the largest pore of HASM specimen were reduced about 54% and by 46.6% than those of wire-feed AM, respectively. The morphology of ferrite at different height of both specimens was different including skeletal, lathy and granular. The tensile strength of HASM specimen was better than that of wire-feed AM, which is mainly attributed to the decrease of porosity and grain size.

Analysis of 179 posterior communicating artery infundibular dilations demonstrating low risk for transformation to aneurysm or rupture and the usefulness of the “round defect”

ObjectiveOutpouchings, particularly those originating from the posterior communicating artery off the internal carotid artery (Pcom-Ops), are often unable to be categorized definitively as aneurysms or infundibula resulting in frequent clinical imaging and follow-up. We aimed to investigate potential correlations between growth and rupture rates and easily definable imaging characteristics in Pcom-Ops. MethodsWe analyzed CT and MR imaging of Pcom-Ops identified in a case series of patients seen between 2007 and 2022. For each outpouching, the length of the base, hypotenuse, and round defect, defined as the deviation from triangular shape, were calculated. These measurements were used to estimate the conical volume and eccentricity of the Pcom-Op. Results179 Pcom-Ops were identified from 152 patients who were followed for an average of for 3.2 ± 3.2 years. Bilateral Pcom-Ops were present in 17.8 % patients and 7.2 % had an underlying connective tissue disease. Only one Pcom-Op in a patient with polycystic kidney disease subsequently became a clear aneurysm after 6.3 years. The average approximated volume and round defect at presentation were 2.3 ± 2.2 mm3 and 0.29 ± 0.16 mm, respectively. Volume and round defect changed minimally over time followed. Outlier analysis of round defect, determined by Z-score more than 3 standard deviations above the mean, was not associated with evolution into clear aneurysms. ConclusionPcom-Ops rarely enlarge or rupture. Pcom-Op eccentricity does not predict high risk Pcom-Ops. Thus Pcom-Ops in general may not require close follow-up over time. However, Pcom-Ops in patients with connective tissue diseases should be monitored more closely.

Addressing Model Uncertainties in Finite Element Simulation of Electrically Stimulated Implants for Critical-Size Mandibular Defects.

Electrical stimulation is known to enhance bone healing. Novel electrostimulating devices are currently being developed for the treatment of critical-size bone defects in the mandible. Previous numerical models of these devices did not account for possible uncertainties in the input data. We present the numerical model of an electrically stimulated minipig mandible, including optimization and uncertainty quantification (UQ) methods that allow us to determine the most influential parameters. Uncertainties in the optimized finite element model are quantified using the polynomial chaos method that is implemented in the open-source Python toolbox Uncertainpy. The volumes of understimulated, beneficially stimulated, and overstimulated tissue are considered quantities of interest because they may significantly impact the expected healing success. Further, the current is a substantial quantity, limiting the lifetime of a battery-driven stimulation unit. With sensitivity analyses, the most critical parameters in the numerical model can be identified. Thus, we can learn which parameters are particularly relevant, for example, when conceptualizing the stimulation unit or planning the manufacturing process. The results of this study show that the parameters of the electrode-tissue interface (ETI), as well as the conductivity within the defect volume, have the most significant impact on the model results. The UQ results suggest that careful characterization of the ETI and the dielectric tissue properties is crucial to reduce these uncertainties. The numerical model regarding uncertainties yields important implications for reliable implant design and clinical translation.

Precise identification of delamination defect based on optimized deep learning method to understand mechanical property reduction

Ceramic matrix composites are advanced thermal structural materials used in aerospace and other fields due to their excellent performance. However, the common delamination defects in the interior can easily lead to material failure, posing significant threats to component reliability. Addressing this issue requires the development of precise and intelligent methodologies for the rapid identification of delamination defects and the evaluation of their impact on mechanical properties. In this study, delamination defects were intentionally introduced into SiCf/SiC composites to facilitate intelligent identification and quantitative analysis. We propose a novel network combining Mamba and Convolutional Neural Network, which surpasses existing models in defect segmentation by precisely capturing both global and local information, while optimizing computational efficiency and memory usage. Mechanical tests reveal that variations in delamination defects lead to an initial reduction followed by an increase in both tensile and compressive strengths. The minimum tensile and compressive strengths are 69.30 % and 74.30 % of those in non-defective control samples, respectively. Tensile strength is more sensitive to defect volume, as the reduced crack propagation path facilitates premature tensile fracture of the fibers, whereas compressive strength is more affected by defect depth due to compressive instability and stress concentration. This strategy provides a novel avenue for the intelligent identification and risk assessment of delamination defects in ceramic matrix composites.

Preparation of Zirconium-Based MOF-Derived Phosphide on GO/MXene Double Substrates for High-Performance Asymmetric Supercapacitors.

At present, it is very necessary to select and prepare suitable positive and negative electrode materials to fabricate high-performance asymmetric supercapacitors. Metal-organic frameworks (MOFs) have garnered significant attention in the energy storage field due to their high conductivity. As a branch, the zirconium organic framework (UIO-66) is a promising porous material due to its large specific surface area and abundant Zr centers. Graphene oxide (GO) and MXene are very suitable as substrate materials for conducting an MOF due to their abundant active sites and adjustable interlayer distance. The GO/MXene@NiZrP prepared through an in situ composite of GO and Mxene with the hydrothermal method and calcining method showed excellent electrochemical performance. Compared with the precursor UIO-66, the specific capacitance of the final product GO/MXene@NiZrP increases more than ten times, mainly because of its special layered porous structure, and GO/MXene@NiZrP has a larger specific surface area, pore volume, and surface defects caused by unstable Zr4+ than those of UIO-66. Using GO/MXene@NiZrP as the positive electrode and biochar (BC) as the negative electrode, an asymmetric supercapacitor, BC//GO/MXene@NiZrP, is assembled. After 10,000 cycles at a current density of 10 A g-1, the capacitance retention remains at 83.3%, showing excellent cycle stability.

The Local Rhombus-Shaped Flap-An Easy and Reliable Technique for Oncoplastic Breast Cancer Surgery and Defect Closure in Breast and Axilla.

Primarily, breast-conserving therapy is an oncological intervention, but eventually it is judged by its cosmetic result. Remaining cavities from tumor resection can promote seromas, delay healing and cause lasting discomfort. Additionally, volume loss, dislocation of nipple/areola and fat necrosis lead to (cosmetically) unfavorable results, aggravated by radiotherapy. Oncoplastic surgery can reduce these sequelae. A local flap that has rarely been used in breast cancer surgery is the Limberg rhombic flap. The tumor defect is planned as a rhombus. The sides of the rhombus are of equal length and ideally have an angle of 60° and 120°. The flap that closes the defect is planned as an extension of equal length of the short diagonal. The second incision of the flap is placed according to the defect angle of 60°, running parallel to the defect at the same length. This creates a second rhombus. The flap is transposed into the defect, and the donor area is primarily closed. It is axially perfused and safe with a 1:1 length-to-width ratio. Compared to local perforator flaps, defect closure is easily managed without microsurgical skills. In the breast, the flap can be used in volume replacement and volume displacement techniques as an all-layer flap to cover defects, or it can be deepithelialized and buried. In the axilla, it can cover full-thickness defects when skin is involved. The advantages of the rhombic flap are its safety and simplicity to add volume and close defects, thus reducing the complexity of oncoplastic surgery.

Effect of Sclerosis Bands in Femoral Head Necrosis on Non-Vascularized Fibular Grafting-A Finite Element Study.

Femoral head necrosis is a challenging condition in orthopaedics, and the occurrence of collapse is an important factor affecting the prognosis of femoral head necrosis. Sclerosis bands are known to influence the collapse of the femoral head, yet there is a lack of research on the biomechanical role of sclerosis bands in non-vascularized fibular grafting surgery. This study aims to evaluate the biomechanical impact of sclerosis bands in femoral head necrosis and their role in non-vascularized fibular grafting surgery (NVFG) using finite element analysis. We constructed 11 finite element models based on CT scan data of a normal hip joint, simulating different sclerosis band thicknesses and defect scenarios. The models were analyzed for changes in femoral head displacement and von Mises stress. We constructed a hip joint model based on CT data from a normal hip joint, and after reconstruction, assembly, and optimization using 3-matic. We created five groups consisting of 11 finite element analysis models of the hip joint. Mesh partitioning and mechanical parameter settings were performed in ANSYS. The changes and differences in femoral head displacement and von Mises stress of these models were analyzed. Increasing sclerosis band thickness led to reduced peak displacement of the femoral head by 28.6%, 42.9%, and 47.6%, and increased surface von Mises stress by 28.3%, 13.8%, and 13.0%, respectively. Post-surgery, peak displacement decreased in all groups compared to pre-surgery levels. Increasing sclerosis band thickness post-surgery resulted in decreased maximum von Mises stress of the femoral head by 13.9%, 3.0%, and 8.1%. Defect volume in the defect groups correlated with increased peak displacement of the femoral head by 10.0%, 30.0%, and 100.0%, and increased surface maximum von Mises stress of the femoral head by 9.3%, 14.0%, and 15.1%. Sclerosis band formation exacerbates von Mises stress concentration on the femoral head surface. However, thicker sclerosis bands improve post-NVFG stability and mechanical performance. Larger anterior lateral sclerosis band defects significantly compromise postoperative stability, increasing the risk of collapse. Protecting the anterior lateral sclerosis band during NVFG surgery is crucial.

Effect of “platelet rich” fibrin with bone marrow aspirate on the regenerative capacity of alveolar bone grafting with iliac bone graft: A randomized controlled trial

Objectives of the Study: (1) To evaluate the effect of platelet-rich fibrin (PRF) with bone marrow aspirate on regenerative capacity in patients undergoing iliac bone grafting for secondary alveolar bone grafting. (2) and to compare it with group 2 where only bone marrow aspirate was used along with iliac bone graft in secondary alveolar bone grafting. Materials and Methods: A prospective study on patients with cleft alveolus, requiring bone grafting and reporting to our unit from October 2018 to October 2020 was included in this study. Group 1 (bone marrow aspirate with PRF along with cancellous iliac bone graft) and Group 2 (bone marrow aspirate concentrate and cancellous Iliac bone graft without PRF). Computerized tomography (CT) scan was done to assess the volume of defect at the following intervals: Pre-op, immediate post-op, and 12 months. The outcome is assessed using a CT scan by statistical analysis. Results: Mean cleft alveolus volume measured preoperatively in group 1 was 2.5cc, post-operatively measured immediately was 3.2cc, and 12 months post-operative was 2.2cc. Mean volume defect in group 2 is 2.3cc, post-operatively measured immediately was 2.6 cc, and 12 months post-operative was 1.9cc. The average resorption rate at immediate post-op to 12 months interval in group 1 was 25% and in group 2 was 30%. The overall percentage of regenerated bone in group 1 was 75% whereas in group 2 it was 70%. Conclusion: Platelet-rich fibrin in combination with bone marrow aspirate and autogenous bone was beneficial in improving the volume of newly formed bone in the reconstruction of the cleft defect and also results in greater osteogenic effect which increases new bone regeneration and better wound healing.

Tetramerization of PKM2 Alleviates Traumatic Brain Injury by Ameliorating Mitochondrial Damage in Microglia.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Microglial activation and neuroinflammation are key cellular events that determine the outcome of TBI, especially neuronal and cognitive function. Studies have suggested that the metabolic characteristics of microglia dictate their inflammatory response. The pyruvate kinase isoform M2 (PKM2), a key glycolytic enzyme, is involved in the regulation of various cellular metabolic processes, including mitochondrial metabolism. This suggests that PKM2 may also participate in the regulation of microglial activation during TBI. Therefore, the present study aimed to evaluate the role of PKM2 in regulating microglial activation and neuroinflammation and its effects on cognitive function following TBI. A controlled cortical impact (CCI) mouse model and inflammation-induced primary mouse microglial cells in vitro were used to investigate the potential effects of PKM2 inhibition and regulation. PKM2 was significantly increased during the acute and subacute phases of TBI and was predominantly detected in microglia rather than in neurons. Our results demonstrate that shikonin and TEPP-46 can inhibit microglial inflammation, improving mitochondria, improving mouse behavior, reducing brain defect volume, and alleviating pathological changes after TBI. There is a difference in the intervention of shikonin and TEPP-46 on PKM2. Shikonin directly inhibits General PKM2; TEPP-46 can promote the expression of PKM2 tetramer. In vitro experiments, TEPP-46 can promote the expression of PKM2 tetramer, enhance the interaction between PKM2 and MFN2, improve mitochondria, alleviate neuroinflammation. General inhibition and tetramerization activation of PKM2 attenuated cognitive function caused by TBI, whereas PKM2 tetramerization exhibited a better treatment effect. Our experiments demonstrated the non-metabolic role of PKM2 in the regulation of microglial activation following TBI. Both shikonin and TEPP-46 can inhibit pro-inflammatory factors, but only TEPP-46 can promote PKM2 tetramerization and upregulate the release of anti-inflammatory factors from microglia.

Impact of Annealing Chemistry on the Properties and Performance of Microporous Annealed Particle Hydrogels.

Microporous annealed particle (MAP) hydrogels are a promising class of in situ-forming scaffolds for tissue repair and regeneration. While an expansive toolkit of annealing chemistries has been described, the effects of different annealing chemistries on MAP hydrogel properties and performance have not been studied. In this study, we address this gap through a controlled head-to-head comparison of poly(ethylene glycol) (PEG)-based MAP hydrogels that were annealed using tetrazine-norbornene and thiol-norbornene click chemistry. Characterization of material properties revealed that tetrazine click annealing significantly increases MAP hydrogel shear storage modulus and results in slower in vitro degradation kinetics when microgels with a higher cross-link density are used. However, these effects are muted when the MAP hydrogels are fabricated from microgels with a lower cross-link density. In contrast, in vivo testing in murine critical-sized calvarial defects revealed that these differences in physicochemical properties do not translate to differences in bone volume or calvarial defect healing when growth-factor-loaded MAP hydrogel scaffolds are implanted into mouse calvarial defects. Nonetheless, the impact of tetrazine click annealing could be important in other applications and should be investigated further.

Response mechanisms for the photopolymerization profiles, microstructures, and properties in ceramics prepared by stereolithography

Insight into the response mechanisms among the photopolymerization process, profile curves, microstructure, and physicomechanical properties is essential for microstructural and performance control during ceramic stereolithographic manufacturing. This work establishes and validates the photopolymerization profile equation and investigates the response mechanisms of photopolymerization profiles on microstructures and lamellar defects and the response mechanisms of cured powder concentration gradient on dimensional shrinkage, porosity, and physicomechanical properties. The results illustrate that the profile control equations perfectly predict the photopolymerization experiment profile and the lamellar profile shape to control the volume of lamellar defects, and the surface microstructures are mainly affected by the z-direction lamellar profile. The optimal surface roughness values of the green bodies before and after sintering are 3.95 μm and 3.32 μm, respectively. Besides, the attenuation of the Gaussian-distributed laser intensity in the slurry results in a gradient change in double-bond conversion to create a gradient in the cured powder concentration. The z-direction shrinkage strongly correlated with the cured powder concentration is much greater than the x- and y-direction shrinkages. The variation range of the anisotropic shrinkage is from 1.54 % to 3.77 %. Furthermore, the cured powder concentration on the top area of the cured layer near the laser irradiation is greater than that on the bottom area away from the irradiation, influencing the physicomechanical properties. Finally, the best process parameters for multiobjective optimization are achieved by combining response surface experiments and principal components analysis. The response mechanisms of the lamellar profile and cured powder concentration are expected to provide new ideas for controlling the performance of vat photopolymerization.

Significance of microstructural defect-tolerant in the battle for survival: Mantis shrimp VS. Nacre

Mantis shrimps use their robust claws to repeatedly strike and break the shells of bivalves during predation without sustaining damage themselves. It appears to be a confrontation between the bouligand microstructure and the brick-and-mortar microstructure of the nacre layer. In the daily struggle for survival, defects are inevitably introduced. To elucidate the mechanical mechanisms exhibited by the two microstructures in the struggle for survival, thus a bold conjecture was proposed: the bouligand structure exhibits less sensitivity to random defects compared to the brick-and-mortar structure, enabling mantis shrimps to survive in the battle for existence. To verify this hypothesis, numerical models of bouligand and brick-and-mortar microstructures were established considering interfacial random defects. The results indicated that for various defect volume fraction, the bouligand structure demonstrates superior mechanical performance compared to the brick-and-mortar structure. In terms of peak load and damage dissipation energy, the bouligand structure exhibits higher tolerance to interfacial random defects than the brick-and-mortar structure, delaying the occurrence of damage in the Bouligand structure while prematurely inducing damage in the brick-and-mortar structure. This study not only reveals the mechanical mechanisms behind the advantages of biological microstructures in the struggle for survival but also provides technical references for future biomimetic microstructure designs.

Microstructural, microhardness and electrical conductivity analysis of AD31T alloy processed by friction stir processing

PurposeThis research aims to examine the impact of friction stir processing (FSP) treatment on an aluminum alloy, especially the AD31T alloy derived from the Al-Fe-Mg-Si system. The aim is to assess the influence of different processing techniques on the microstructure and physical and mechanical characteristics of the material, with a specific focus on structural and bulk imperfections inside the stir zone (SZ).Design/methodology/approachThe study demonstrates that augmenting the linear velocity of the tool within the 25–100 mm/min range results in significant enhancements. The enhancements include a decrease in the heat-affected zone (HAZ), a reduction in the extent of volume defects inside the SZ and a more uniform deformation. The microstructural analysis results are corroborated by data acquired from microhardness and electrical conductivity studies, confirming the beneficial influence of modifying the tool’s linear velocity on the material parameters.FindingsThis study provides significant observations on the changes in microstructure and the generation of flaws throughout the process of FSP of AD31T alloy. These results have practical implications for improving the characteristics of the alloy and optimizing the production conditions.Originality/valueAll samples exhibit a distinct reduction in electrical conductivity within the initial third of the sample, aligning with the transitional region between the base metal (BM) and the HAZ. This underscores the importance of understanding the transitional zones during FSP.

Study on the effect of multi-factor compound action on long-term tensile performance of GFRP composite pipe and life prediction analysis

In this work, the glass fiber reinforced plastic (GFRP) composite pipes used as sewerage pipes in oil and gas field environments were studied. The accelerated aging experiments were carried out under the simulated environments of three typical oil field media which including circulating air, simulated produced water and standard simulated oil. Scanning electron microscopy (SEM) was adopted to observe the microscopic morphology of the aged GFRP tubes under the three conditions. The microstructural characteristics of the aged tubes and the evolution process of internal defects were also analyzed and evaluated in combination with micro-CT technology. The attenuation pattern of the hoop tensile strength of the aged pipes was measured via the separation disk method, and the service life prediction was carried out based on the Arrhenius theory with the hoop strength as the life index. The results show that the accumulation of aging time and continuous heat input will aggravate the expansion of internal pores and cause the aggregation of small-volume defects into large-volume defects. Especially in the simulated oil environment, which has the highest sensitivity to defects. The maximum porosity reaching 1.5 % and the maximum volume of individual defects exceeding 106 μm3 after aging for 4000 h at 95 °C. The thermal aging process under the three environmental conditions had similar aging characteristics, and interfacial damage of the glass fibers was observed in all of them. The variability of hydrothermal aging is related to the hydrolytic behavior of the glass fibers, which is associated with the progressive dissolution damage of the SiO2 network in the glass fibers, as well as the breaking of silane bonds. Thus, the hydrothermal environment had the most significant effect on the hoop tensile strength decay. Ultimately, 75 % strength retention was taken as the end-of-life indicator. The predicted service life based on the Arrhenius model for the three environments of thermo-oxygen, hydrothermal and simulated oil were 23.5, 23.1 and 28.5 years at 20 °C, and 12.2, 4.9 and 10.3 years at 40 °C, respectively.

Applications of Extracellular Matrix Biomaterial in Tongue Reconstruction.

Tongue neoplasms are common in the head and neck region and are primarily treated through surgical interventions. Various reconstruction techniques, such as primary closure, skin grafts, skin substitute biomaterials, and free tissue transfer, are used to address the resulting defects. This study provides an overview of our experience utilizing extracellular matrix-based biomaterials (ECM) for the reconstruction of tongue defects and evaluates the mean volumetric size of postsurgical tongue. This retrospective case series evaluated subjects with tongue defects secondary to benign or malignant resections who underwent reconstruction with ECM-based biomaterials at Ascension Hospital from July 2022 to May 2023. Descriptive variables were collected, and descriptive statistical analyses were conducted. The primary outcome was the volume of postsurgical defect reconstructed. Twenty-five subjects were included: 10 had benign pathology and 15 had malignancy. The mean reconstructed defect volume was 12.65cm 3 , ranging between 2 and 35cm 3 . Postoperative bleeding, mainly linked to anticoagulation medication, occurred in 20% (n=5) of the cases, and the rate of need for additional procedures was 8%. In conclusion, ECM-based biomaterials are suitable for reconstructing varying sizes of postsurgical tongue defects with no donor-site morbidity. Carefully considering patient factors, including anticoagulation medication use and defect volume, is essential in optimizing outcomes.