Adjacent Defects Research Articles

Quantitative Evaluation Of Weld Defects Based On Overall Shape Three-Dimensional Reconstruction

The evaluation of the size of weld defects is crucial in assessing the quality of weld structures. In this study, a novel quantitative evaluation method for weld defects was proposed based on 3D reconstruction using slices. The method includes two significant contributions. First, the supervised defect segmentation method was introduced, which uses the results of the previous slice to supervise the segmentation of the current slice based on slight changes in adjacent defect slices. This ensures accurate segmentation of all defects. Second, the subpixel edge extraction method combining the Canny operator and cubic spline interpolation was proposed to improve the accuracy of edge detection. The proposed method was evaluated using 15 defects. The experimental results showed that the average errors of inclusion defects, incomplete-penetration defects, and incomplete-fusion defects were 13.6%, 8.18%, and 13.9%, respectively. Compared with the other methods, the proposed method not only had higher accuracy but also provided the volume value of defects.

Angulated Edge Intrinsic Defect in Carbon as Bridge‐Adsorption Site of CO for Highly Efficient CO2 Electroreduction

AbstractPervasive intrinsic defects have a significant impact on the electrocatalytic activity of carbon materials, but previous research has focused on the effects of topological structures exclusively. Herein, a compelling demonstration of the pivotal role played by the positions and spatial arrangement of intrinsic defects in determining their efficacy for electrochemical CO2 reduction (ECR) is presented. Theoretical calculations reveal a substantial reduction in energy barriers for *COOH formation at intrinsic defects positioned along the edges while hindering the transformation of *COOH to *CO in the ECR process. To address this issue, a sea urchin‐like nanocarbon (F1100) is designed, which provides adjacent intrinsic defects located in V‐type arranged carbon nanorods. The angulated edge intrinsic defects facilitate the bridge adsorption of carbon monoxide (CO), as confirmed by in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy, thereby enhancing the specific activity of ECR on intrinsic carbon defects. In a 0.1 m potassium bicarbonate (KHCO3) solution, F1100 achieves a FECO of 95.0%, while in an ionic liquids‐based electrolyte, a current density of 90.0 mA cm−2 is obtained with nearly complete conversion of CO2 to CO in an H‐type cell.

Oxygen vacancy induction strategy to regulate the evolution of valence- and free-electrons for boosting visible photodegradation of tetracycline hydrochloride

The generation, migration and reaction paths of electrons are the key steps for photodegradation of pollutants. However, efficient operation of the above pathways is still challenging. Herein, by strong coordination and slow pyrolysis, we constructed a narrow band Zn-Mn bimetallic photoactive core-shell material (Mn@Zn-N-C, Eg = 3.38 eV) with abundant oxygen vacancies for enhancing the above electronic paths. The photodegradation experiments of tetracycline hydrochloride (TCH) showed that the formation and transfer of vacancy-induced free electrons in the synthesized Mn@Zn-N-C was the key to improve the photocatalytic activity. The DFT calculation results revealed that the photogenerated electrons can transfer along the Mn-O-Zn bridge in Mn@Zn-N-C, and promote the formation of MnIV, which directly capture the free electrons and reset itself to MnII site. In this case, the introduction of Mn would enhance the separation of h+ and e-. The adjacent vacancies and defects then also trapped the above free electrons and hinder the recombination of photogenerated carriers. Simultaneously, the localized valence electron transfer between the above redox pairs (Mn4+/Mn2+ and Zn2+/Zn0) also promoted the long-term stability of the photocatalytic process. In summary, using vacancy induction strategy to regulate the evolution of valence- and free-electrons is a promising method to improve the production-transfer-utilization efficiency of photogenerated carriers.

Dual defect regulation of BiOCl halogen layer enables photocatalytic O2 activation into singlet oxygen for refractory aromatic pollutant removal

The generation of singlet oxygen (1O2) based on photocatalytic activation O2 is considered to have important application prospects in purifying refractory organic pollutants in water. However, the uncertain dual pathway transformation of activated O2 severely limits the generation of 1O2. In this work, we show a robust BiOCl with dual defects (adjacent I-substitution defect and Cl vacancy) in halogen layer for the selective activation of O2 to generate 1O2. Combining experiments and theoretical calculations, we confirm that dual defects are beneficial in optimizing band structures, improving carrier separation efficiency, and promoting O2 adsorption and activation. More importantly, it is confirmed that dual defects can directionally convert O2 into 1O2 by increasing the thermodynamic conversion energy barrier of non-1O2 conversion pathways and serving as a necessary site for 1O2 generation with dual functions of oxidation and reduction. Applying dual defect modified BiOCl to the removal of refractory aromatic pollutants in water, it is found that it has efficient and stable photocatalytic degradation efficiency and broad environmental adaptability. This work not only provides in-depth insights into the mechanism of photocatalytic activation of O2 to selective produce 1O2, but also lays the foundation for further development of highly active photocatalysts for environmental remediation and energy conversion.

In situ X-ray tomography of fracture behaviour in low-porosity L-PBF AlSi10Mg alloy with laser shock peening

ABSTRACT In this study, we employed a novel hybrid AM process, in which periodic laser shock peening (LSP) treatments were added to the standard laser powder bed fusion (L-PBF) process, for fabricating the AlSi10Mg alloy. As a result, the porosity of the alloy was reduced by approximately 90%. To monitor damage evolution, we conducted in situ tensile tests using high-resolution synchrotron radiation X-ray micro-computed tomography. The results indicate that in the LSP-treated L-PBF AlSi10Mg alloy, with a porosity of around 0.05%, the plasticity of vertical tensile samples significantly increases, and the fracture strain closely resembles that of the horizontal sample. The reduction in porosity results in increased spacing between adjacent defects, which decreases the interaction between defects. Consequently, the rapid fracture caused by the merge of large defects is prevented. Notably, micro-cracks observed in the vertical samples before tensile fracture primarily originates at the molten pool boundaries rather than from defects.

Fibular Allograft Osteoplasty and Silicone Arthroplasty following Gunshot Injury of the Metacarpal

Summary: The complexity of a gunshot wound to the hand with segmental bone loss and adjacent joint disruption presents a unique challenge for the reconstructive surgeon. There are several options for posttraumatic reconstruction of hand joint defects, ranging from arthrodesis, implants, and autologous arthroplasty. Despite the abundance of literature regarding guidelines for isolated osteoplasty and arthroplasty, there are only case reports describing management of bone and joint defects, all within the setting of cancer resection. This case report presents a 24-year-old, right-hand dominant man with a gunshot wound to his left hand involving the fifth metacarpal and metacarpal phalangeal joint. The metacarpal was reconstructed with a fibular bone allograft with simultaneous placement of a silicone arthroplasty implant, allowing preservation of motion at the metacarpal phalangeal joint with satisfactory functional outcomes. This illustrates the feasibility of successfully reconstructing segmental bone loss and adjacent joint defects simultaneously in the traumatic setting of firearm injuries.

Facile synthesis of platinum-loaded carbon nanosheets with high specific surface area for efficient CWAO of ammonia nitrogen: A low-cost alternative route for treating ammonia containing wastewater

Deep treatment is an important tool to solve the environmental pollution of ammonia-containing wastewater. Considering the stability and economy of industrial application, we propose a simple and economical synthesis strategy. The procedure is based on the carbonization of citrate at elevated temperatures to synthesize high specific surface area and pore-rich carbon nanoflowers, and carbon nanoflower-loaded Pt catalysts were constructed for the catalytic wet air oxidation (CWAO) of ammonia-containing wastewater. The results showed that the synergistic effect of Pt, edge carbon and carboxyl groups led to the increase of CWAO activity. During the reaction, Pt activated NH3 to put it in a high-energy state, and there was a positive synergistic effect between the oxygen-containing functional groups (carboxyl groups) on the surface of the porous carbon nanoflowers and the edge carbon exposed at the adjacent defect sites, which promoted the activation of O2 and the generation of reactive oxygen species. At 200 °C, the Pt1/PC catalysts showed high activity and hydrothermal stability for CWAO of NH3. The conversion of NH3 was 98.24 % within 4 h, and the selectivity of N2 was 100 %. The total nitrogen (TN) was reduced to below 15 mg‧L−1, which meets the Chinese emission standard for TN in petrochemical industry. Therefore, the novel catalyst proposed in this study effectively solved the problems of complicated catalyst synthesis steps and poor hydrothermal stability in ammonia CWAO studies. The catalyst has potential industrial applications for CWAO of ammonia-containing wastewater.

High-frequency vortex dynamics and losses in the mixed state of nanostructured superconductors with columnar defects

We suggest a theoretical model for the microwave response of Abrikosov vortices in nanostructured superconductors with columnar defects, which serve as effective pinning sites for vortices that are considered elastic strings. For this case, we suppose that microwave losses related to the vortex oscillations in a microwave field arise caused by viscous oscillations of vortex kinks, which connect different parts of the vortex line pinned on adjacent columnar defects and vortex segments pinned on these defects. We consider the case of inclined magnetic field H, which creates vortex staircases consisting of pinned vortex segments and vortex kinks inside the superconductor. In this case, rf losses due to viscous kinks oscillations under the microwave current action arise even at T = 0 if the inclination angle of the magnetic field θΗ, concerning the columnar pinning site axis (z axis), exceeds some locking angle value θL.

In-situ construction of N-doped hollow carbon polyhedral cage anchored Co-Ni dual binding sites as nanoreactor for efficient real lignin oil hydrodeoxygenation

Rational design multifunctional nanoreactor with high activity under H2-free/low-H2 conditions for lignin hydrodeoxygenation reaction (HDO) is attractive for sustainable energy conversion. Here, strategy for in-situ assembly-etching was proposed to prepare N-doped hollow carbon polyhedral cage anchored Co-Ni dual binding sites as nanoreactors (CoxNiy/NC). Its unique and controllable hollow structure exhibits high content of pyridine-N as Lewis-base site for adsorption of substrate, and in adjacent nitrogen defect sites as active metal anchors enabled the Co2Ni1/NC to perform perfect the hydrodeoxygenation of real lignin oil. The conversion of lignin pyrolytic oil to cycloalkane products was achieved under 0.2 MPa H2 and 3 h, the yield of total liquid product and the cyclohexane were 87.8 wt% and 53.4 wt%, respectively. This research provides a novel way for upgrading raw bio-oil to high-value products under low energy consuming conditions.

Study on Evaluation Method of Failure Pressure for Pipeline with Axially Adjacent Defects

Study on Evaluation Method of Failure Pressure for Pipeline with Axially Adjacent Defects

Comparative evaluation of pinhole surgical technique with and without A-PRF in the treatment of multiple adjacent recession defects: A clinico radiographic study.

To evaluate and compare efficacy of pinhole surgical technique (PST) alone and with advanced platelet rich fibrin (A-PRF) in the management of bilateral multiple adjacent gingival recession defects (MAGRD). One hundred and sixty five MAGRD were randomly assigned to control group (treated with PST) and test group (PST with A-PRF). Clinical parameters of gingival recession depth (GRD), gingival recession width (GRW), width of keratinised gingiva (WKG), complete root coverage (CRC) and gingival thickness (GT) on ST-CBCT was measured at 2, 4 and 6 mm apically from the gingival margin. Also, root coverage aesthetic score and patient satisfaction ratings were recorded at baseline, 6 and 12 months postoperatively. Substantial reduction in GRD (Test: 1.29 ± 0.69 mm and Control 0.98 ± 0.30 mm) (p < 0.001) and GRW (Test: 2.03 ± 0.90 mm and control 1.73 ± 0.99 mm) (p < 0.05) with associated gain in WKG and GT was observed (p < 0.001). Mean GT values were increased in both the groups at 2, 4 and 6 mm from the crest. Comparison of Test and Control groups yielded significant reductions in GRD (-0.17 ± 0.56 mm) and WKG (0.73 ± 1.07 mm) favoring the Test group (p < 0.05). Similar increase in GT was observed with better results in Test than control group. (p < 0.001). Both groups exhibited sound clinical outcomes with test group offering better resolution of MAGRD in comparison to control group. Also, it enhances clinical and therapeutic end results in terms of attaining reduction in GRD and GRW along with greater gain in KTW and GT. PST as a minimally invasive approach has numerous benefits, some of which include the absence of scarring and improved aesthetics linked to faster wound healing. The addition of A-PRF enhances the intended therapy outcomes, which is beneficial for both patients and professionals in the field of periodontics.

A novel assessment method to identifying the interaction between adjacent corrosion defects and its effect on the burst capacity of pipelines

This work provides a new systematic evaluation method to assess the interaction between adjacent corrosion defects and its effect on the integrity of pipelines. First, a finite element (FE) model of a pipeline containing adjacent defects (defects in longitudinal, circumferential and diagonal alignments) was developed. Then, the detailed relationships between defect spacing, and geometry, as well as the burst pressure of the pipe were investigated. At last, an interaction identification criterion applicable to asymmetrical defects was proposed, whose accuracy and reliability of the criterion were validated by FE simulations. The results show that the arrangement of corrosion affects the effect of interaction between adjacent defects. Regarding defects in longitudinal and circumferential alignments and with different depths, the increase of defect spacing strengthens the interaction between defects. For diagonally and circumferentially aligned defects with an identical depth, interaction strength tends to decrease first and then increase with the rise of defect spacing. An increase in defect depth exacerbates the interaction between adjacent corrosions. Similarly, an increase in the length of the shorter defect enhances the interplay between defects, which thus reduces the burst capacity of the pipe. When the length of the longer defect in adjacent defects increases, the interaction between the defects will be weakened, and the burst pressure of the pipeline is mainly dominated by the longer defect. Diagonally aligned defects show the strongest interaction effect when their overlapped distance in axial projection equals the sum of depths of adjacent defects, followed by defects in a longitudinal alignment. Besides, defects in a circumferential alignment have little effect on the failure pressure of the pipe. It is expected that the proposed interaction assessment criterion for adjacent defects with different arrangement types can provide a reference for assessing the integrity of pipelines with cluster corrosion defects.

Murine models of orthopedic infection featuring Staphylococcus aureus biofilm.

Introduction: Osteomyelitis remains a major clinical challenge. Many published rodent fracture infection models are costly compared with murine models for rapid screening and proof-of-concept studies. We aimed to develop a dependable and cost-effective murine bone infection model that mimics bacterial bone infections associated with biofilm and metal implants. Methods: Tibial drilled hole (TDH) and needle insertion surgery (NIS) infection models were compared in C57BL/6 mice (female, ). Metal pins were inserted selectively into the medullary canal adjacent to the defect sites on the metaphysis. FreeStaphylococcus aureus(ATCC12600) or biofilm suspension (ATCC25923) was locally inoculated. Animals were monitored for physiological or radiographic evidence of infection without prophylactic antibiotics for up to 14 d. At the end point, bone swabs, soft-tissue biopsies, and metal pins were taken for cultures. X-ray and micro-CT scans were performed along with histology analysis. Results: TDH and NIS both achieved a 100 % infection rate in tibiae when a metal implant was present with injection of free bacteria. In the absence of an implant, inoculation with a bacterial biofilm still induced a 40 %-50 % infection rate. In contrast, freely suspended bacteria and no implant consistently showed lower or negligible infection rates. Micro-CT analysis confirmed that biofilm infection caused local bone loss even without a metal implant as a nidus. Although a metal surface permissive for biofilm formation is impermeable to create progressive bone infections in animal models, the metal implant can be dismissed if a bacterial biofilm is used. Conclusion: These models have a high potential utility for modeling surgery-related osteomyelitis, with NIS being simpler to perform than TDH.

Mechanical synergistic interaction between adjacent corrosion defects and its effect on pipeline failure

This work provides a new comprehensive assessment method to determine the complex mechanical interaction of adjacent corrosion defects. Firstly, a three-dimensional (3D) finite element model of pipelines containing adjacent defects (involving longitudinally aligned, circumferentially aligned, and diagonally aligned defects) was developed and validated by full-scale burst tests. Then, the synergistic stress interaction between adjacent defects was analyzed, and the relationship between the burst position of the pipeline and defect spacing was determined. At last, the applicability of several commonly used critical spacing rules for identifying the interaction between adjacent defects was compared and discussed in detail. The results show that the failure position of the pipeline containing adjacent defects is related to the relative position of defects. For longitudinally aligned corrosion defects, the stronger the interaction between defects (i.e., the shorter the distance between two defects), the closer the failure position of the pipeline to the center of the defect spacing. For circumferentially aligned corrosion defects, the failure position of the pipe tends to move from the defect edge to the geometric center of the defect with increasing defect spacing. For diagonally aligned defects, the failure position is generally located on the path connecting the defect and the spacing. The currently available evaluation criteria for identifying circumferentially interacting defects display the most accuracy, and the identification effect of diagonally aligned defects is the poorest. In addition, the critical spacing rule proposed by Li presents the highest precision in identifying the interacting defects. The results are expected to provide a stress synergistic failure assessment method for pipelines containing cluster corrosion defects in engineering.

Experimental study on strain and failure location of interacting defects in pipeline

The interaction between adjacent defects significantly influences the internal pressure loading capacity of corroded pipelines, and the failure pressure of the interacting defects is lower than that the defects would attain when they were isolated. Therefore, it is necessary to study the interaction mechanism between different defects. The experimental program described in the paper involves seamless steel tubes with D/t = 31 and different sizes of interacting defects. The fluid is passed inside the sealed pipeline and the failure pressure of such locally corroded pipeline was obtained experimentally. The strains within and between the defects were measured using strain gauges and the measured data were analyzed. The results of full-scale corroded pipeline tests showed that the strain of failure defect will rise first and then decrease, and the interaction between this defect and adjacent defects is the most obvious. Through the analysis of the failure location of interacting defects with internal pressure, it can be seen that the failure location was the defect with the lowest internal pressure bearing capacity for adjacent defects with significantly different failure pressures. In contrast, the failure location was the defect in the middle of the corrosion region for adjacent defects with no significant difference in failure pressure.

Radiographic angle width as predictor of clinical outcomes following regenerative periodontal therapy with enamel matrix derivative. A retrospective cohort study with a mean follow-up of at least 10 years.

To assess the association between the baseline radiographic defect angle and the long-term clinical outcomes following periodontal regenerative therapy with enamel matrix derivative (EMD). Baseline periapical radiographs obtained from a cohort of patients treated with periodontal regenerative therapy were digitized and the radiographic angle width between the root surface and the bony wall of the adjacent intraosseous defect was calculated and reported (in degrees). Changes in pocket probing depth (PD) and clinical attachment level (CAL) were assessed and reported (in mm). Clinical outcomes were evaluated at baseline (T0), 6 months following therapy (T1), and at the latest follow-up (T2). Thirty-eight defects in 26 patients enrolled in supportive periodontal care for a mean period of 10.4 years (range 8.0 to 15.5 years) were available for analysis. The mean PD change between T0 and T2 was 2.33 ± 1.66 mm at teeth with a defect angle width < 20 degrees and 0.86 ± 1.66 mm at teeth with a defect angle width > 30 degrees (P = .021). When the baseline radiographic angle width was < 20 degrees the probability of obtaining a CAL gain > 3 mm was 1.5-times higher (95% CI 0.19 to 13.8) at T1 and 2.5-times higher (95% CI 0.40 to 15.6) at T2 compared with defects with a radiographic angle width > 30 degrees. Within their limitations, these results indicate that pretherapeutic measurement of the radiographic defect angle width might provide relevant information on the short-/long-term clinical outcomes following regenerative periodontal therapy with EMD.

A Novel Assessment Method to Identify the Interaction between Adjacent Corrosion Defects and its Effect on the Burst Capacity of Pipelines

A Novel Assessment Method to Identify the Interaction between Adjacent Corrosion Defects and its Effect on the Burst Capacity of Pipelines

Mechanical and cracking behavior of porous rock models containing random circular defects under uniaxial compression

Circular defects are widely distributed in porous rock materials, and the defects greatly affect the mechanical behavior and crack evolution of rock masses. In this paper, numerical models containing random circular defects are constructed based on discrete element method. Then, the uniaxial compressions are numerically performed to reveal the influence of the porosity or size homogeneity of the defects on the mechanical behavior, crack evolution, and acoustic emission (AE) events of the models. The results suggest that a univariant increase in porosity leads to a nonlinear decrease in the peak strength and a linear decrease in the elastic modulus. The number of cracks and AE events decrease with increasing porosity. As the size homogeneity coefficient increases, the peak strengths show a slight linear rise, while the elastic modulus values show a minimal linear downward trend, and the number of cracks and AE events show wave-like increases. The cracks first appear at the location with dense defects, and the cracks initiate from the top and bottom of the circular holes. The crack propagation and intersection modes between two adjacent defects are affected by their positions. These findings provide a reference for the fracture mechanism of rock with random circular defects.

Investigating the Combined Effect of Multiple Dent and Bump Faults on the Vibrational Behavior of Ball Bearings

The rolling element bearing is a fundamental component of any rotating machinery. During operation, wear debris and lubricant impurities create dents and bumps on the bearing raceway surfaces. Such localized defects produce transient vibration impulses at one of the bearing characteristic frequencies. Having a combination of multiple types of point defects on the raceway results in superimposed vibration patterns, which reduce the ability to recognize these defects’ effects. In this paper, a 6-DOF dynamic model is developed to accurately investigate the vibration characteristic of a ball bearing with a multipoint defect comprising a dent and bump on its raceway surface. The model considers the effects of time-varying contact force produced due to defects, lubricant film damping, bearing preload, and the inertia effect of rolling elements. The simulation results reveal the vibration behavior of multipoint defect bearings. In addition, bearing vibration response is affected by the number of defects, the angle between them, and the type and size of each defect. Furthermore, it is challenging to predict bearing defects parameters such as the numbers, types, sizes, and angles between adjacent defects from acceleration signal analysis without jerk signal analysis. The validation of the model is proved using signals from the Case Western University test setup.

V-016 PARAHIATAL HERNIA: A RARE CASE OF DIAPHRAGMATIC HERNIA ROBOTICALLY REPAIRED

Abstract Aim Parahiatal hernia is a rare type of diaphragmatic hernia, consisting in a adjacent but separated defect, lateral to the oesophageal hiatus and crus. It's not so familiar for surgeons, preoperative diagnosis is unlikely to be confirmed, and it is mostly found incidentally during intervention, leading to a complex and difficult repair. We present a case of parahiatal hernia robotically treated with the aim of emphasizing how robotic system can successfully help surgeons in performing even unexpected confusing and challenging anatomic dissections and procedures. Material and Methods A 65-year-old woman underwent robotic parahiatal hernia repair at our Institution. Four robotic trocars were positioned along the transverse umbilical line with the additional Air-seal port at the periumbilical left side for assistant's use. Dissection and isolation of both parahiatal defect and crural musculature were performed; the defect was closed with not absorbable barbed suture, conventional iatoplasty was also performed and a biosynthetic mesh was placed and fixed as a reinforcement. Results The duration of the intervention was of 100 minutes. No. intr- or post-operative complications occurred. Blood loss were inferior than 100 millilitres. The patient started oral intake at the second post-operative day and after discharged. At six months no recurrences were detected. Conclusions Parahiatal hernia are rare entities of which surgeons should be aware. Robotic treatment is safe and feasible and it represents a good tool for a successful management.