Secondary Defects Research Articles

HADHA Regulates Respiratory Complex Assembly and Couples FAO and OXPHOS.

Oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) are key bioenergetics pathways. The machineries for both processes are localized in mitochondria. Secondary OXPHOS defects have been documented in patients with primary FAO deficiencies, and vice versa. However, the underlying mechanisms remain unclear. Intrigued by the observations that regulation of supercomplexes (SCs) assembly in a mouse OXPHOS deficient cell line and its derivatives is associated with the changes in lipid metabolism, a proteomics analysis is carried out and identified mitochondrial trifunctional protein (MTP) subunit alpha (hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit alpha, HADHA) as a potential regulatory factor for SCs assembly. HADHA-Knockdown cells and mouse embryonic fibroblasts (MEFs) derived from HADHA-Knockout mice displayed both reduced SCs assembly and defective OXPHOS. Stimulation of OXPHOS induced in cell culture by replacing glucose with galactose and of lipid metabolism in mice with a high-fat diet (HFD) both exhibited increased HADHA expression. HADHA Heterozygous mice fed with HFD showed enhanced steatosis associated with a reduction of SCs assembly and OXPHOS function. The results indicate that HADHA participates in SCs assembly and couples FAO and OXPHOS.

Sink strength of grain boundaries for point defects in irradiated ferritic/martensitic steel

Dislocation-free ferritic/martensitic steel: F82H was prepared by heat-treatment in the appropriate condition in order to investigate the sink strength of grain boundaries for point defects. The size and the areal density of irradiation-induced secondary defects, such as dislocation loops and voids, were investigated in electron-irradiated F82H. The in-situ irradiation experiment resulted in the formation of a defect free zone and the gradient distribution of loop and cavity as a function of distance from boundaries, especially around prior austenite grain boundaries. The atomic density ratio of grain boundary planes is a key parameter in determining the width of defect free zone; a grain boundary with a higher atomic density ratio typically exhibits a wider defect free zone compared to one with a lower ratio. These results clearly indicate that the distribution of irradiation-induced secondary defects in ferritic/martensitic steels is not uniform and is likely controlled by the sink strength, as characterized by the atomic density ratio of grain boundary planes.

Combined biomaterial scaffold and neuromodulation strategy to promote tissue repair and corticospinal connectivity after spinal cord injury in a rodent model

Spinal cord injury (SCI) damages the trauma site, leading to progressive and secondary structural defects rostral and caudal to the injury. Interruption of ascending and descending pathways produce motor, sensory, and autonomic impairments, driving the need for effective therapies. In this study, we address lesion site repair and promoting descending projections using a combined biomaterial-neuromodulation strategy in a rat model of cervical contusion SCI. To promote tissue repair, we used Chitosan fragmented physical hydrogel suspension (Cfphs), a biomaterial formulation optimized to mitigate inflammation and support tissue remodeling. To promote descending projections, we targeted the corticospinal motor system with dual motor cortex–trans-spinal direct current neuromodulation to promote spared corticospinal tract (CST) axon sprouting rostral and caudal to SCI. Cfphs, injected into the lesion site acutely, was followed by 10 days of daily neuromodulation. Analysis was made at the chronic phase, 8-weeks post-SCI. Compared with SCI only, Cfphs alone or in combination with neuromodulation prevented cavity formation, by promoting tissue remodeling at the injury site, abrogated astrogliosis surrounding the newly formed tissue, and enabled limited CST axon growth into the remodeled injury site. Cfphs alone significantly reduced CST axon dieback and was accompanied by preserving more CST axon gray matter projections rostral to SCI. Cfphs + neuromodulation produced sprouting rostral and caudal to injury. Our findings show that our novel biomaterial-neuromodulation combinatorial strategy achieves significant injury site tissue remodeling and promoted CST projections rostral and caudal to SCI.

303. VACUUM-STENT TREATMENT FOR TRANSMURAL DEFECTS IN THE UPPER GASTRO-INTESTINAL TRACT: CASE SERIES AND NEW INSIGHTS IN A TERTIARY REFERRAL CENTER

Abstract Background Transmural defects in the upper gastro-intestinal (GI) tract are associated with severe morbidity and mortality. Endoscopic vacuum therapy (EVT) has recently been established as promising endoscopic treatment option for such defects and is most often applied using endoscopically placed vacuum-sponges. The vacuum-stent is a novel device to apply EVT, combining the advantages of negative pressure wound therapy and an intraluminal stent, allowing for oral intake. Methods The aim of this prospective cohort study is to describe the experiences of, and lessons learned by a tertiary referral center with EVT experience since 2018, regarding the vacuum-stent for transmural defects in the upper GI tract. All patients treated with a vacuum-stent between November 2022 and October 2023 were included. Outcome measures included successful defect closure, reasons of treatment failure, adverse events and strictures. Results 31 patients were included. Baseline characteristics and outcomes are displayed in Table 1. Success rates of combined vacuum-stent and –sponge treatment and vacuum-stent treatment alone were respectively 83% and 78%. In this cohort, some notable reasons of failure were observed: a defect too close to the upper esophageal sphincter (UES), inadequate vacuum on the esophago-jejunal anastomosis, a carcinoma at a persisting perforated ulcer, and adverse events. Two adverse events occurred (6%): two patients developed a secondary defect at the site of the proximal vacuum-stent flange, of whom one had a cervical anastomosis with a narrow proximal esophagus and one Boerhaave syndrome. Three out of four patients with a severe structure had underwent a McKeown esophagectomy. Conclusion The vacuum-stent is a valuable treatment option for AL after Ivor Lewis esophagectomy, Boerhaave syndrome and iatrogenic defects with success rates of 78-83%. Treating cervical anastomotic leaks is not recommended by us, due to the narrow lumen of the proximal esophagus, the proximity of the UES and high risk of severe strictures. Furthermore, caution is recommended in case of a narrow esophagus. In our experience, vacuum-stent and –sponge treatment complement each other and might be indicated in different situations. Sharing experiences on the topic is important to assess the best techniques and indications, to be able to reach the full potential of the vacuum-stent and further increase the success rate.

(Dielectric Science and Technology Poster Award, 2nd Place) Activation of Amine Chemistries for the Enhanced Particle Removal Efficiency of CeO2 Nanoparticles Via Megasonic Processing Conditions

With the persistent advancement of semiconductor technology, the demand for high-efficiency device manufacturing processes has surged. Chemical Mechanical Planarization (CMP) is a cornerstone for achieving angstrom-scale surface uniformity crucial for integrated circuits (IC) and logic devices. Shallow Trench Isolation (STI) CMP involves the selective removal of bulk oxide to electrically isolate active components on wafer surfaces. The modulation of the Ce3+ to Ce4+ surface state is essential for improved performance in both CMP and post-CMP (p-CMP) applications. Ce3+ is ideal for oxide material polishing due to its strong adherence to oxide surfaces, while Ce4+ is optimal for p-CMP cleaning, given its weak bond to oxide surfaces. Current p-CMP industry-standard methods utilize mechanical approaches, such as polyvinyl alcohol (PVA) brush scrubbing. However, this process induces high levels of shear force (SF), leading to secondary defects on the wafer surface (i.e. scratches, corrosion, increased surface roughness). To address these limitations, non-contact cleaning methods utilizing megasonic energy have emerged, which rely on generating reactive oxygen species (ROS) to induce particle removal. Thus, this study focuses on enhancing ceria particle removal during post-CMP cleaning by employing amine-based chemistries coupled with megasonic energy. While preliminary results imply that the mechanical cavitations induced by megasonic waves improve cleaning efficiency, this method will be optimized via the introduction of amine-based chemistries. Specifically, this work aims to leverage the unique properties of amines coupled with megasonic energy to facilitate enhanced ceria removal through electron donation, inducing a reduction in the oxidation state of ceria from Ce³⁺ to Ce⁴⁺. This approach improves particle removal while limiting secondary defects, enhancing redox activity induced by megasonic waves and chemical interactions. The mechanisms behind this method will be validated with CeO2 oxidation state kinetics, interfacial frictional changes, wafer surface roughness analysis, and SEM validation of particle removal efficiency.

(Invited) Design of Reduced Shear Force Cu Cleaning Processes Via α-β-Unsaturated Chemistries for Enhanced BTA Residue Removal

As integrated circuit and logic devices continue to decrease, limiting induced defectivity during Chemical Mechanical Planarization (CMP) processes (polishing and substrate cleaning) is imperative. Defects resulting from the CMP process can be classified as mechanical (i.e., scratching), chemical (i.e., corrosion), or physiochemical (i.e., adsorbed contaminants) according to the mechanism of formation. Traditionally, a contact cleaning method implements a polyvinyl alcohol (PVA) brush to transfer cleaning chemistry to the substrate of interest and provides the necessary mechanical energy for defect removal. While this process effectively removes contaminants, its reliance on shear forces can induce secondary defect modes, such as scratching. One major challenge for the post-CMP cleaning of Cu substrates is the polymeric residue film comprised of BTA-Cu+ complexes that propagate during the CMP polishing process. The current and most effective mode to mitigate this “residue defect” is coupling brush-induced shear force with additives that promote interfacial redox reactions to remove residues through an undercutting mechanism. This work focuses on developing a “softer” and additive structure-based approach that drives less aggressive interfacial shear between the brush and wafer substrate. More specifically, α-β-unsaturated additives with diverse functionality (i.e., -unsaturated carboxylic acids, carboxylic acids, and unsaturated benzaldehydes) will be tested to evaluate their efficacy to “overcut” the organic residue via a proposed aza-Michael addition reaction pathway. This “overcutting” mechanism relies on additional modes of interaction (i.e., p-stacking, H-bonding, conformational relationships, etc.) with the BTA- Cu+ polymeric residue film. A suite of dynamic techniques (i.e., Tafel analysis, OCP vs. time, contact angle, additive diffusion analysis, and shear force) will attempt to correlate the additive structure and reaction mechanism to organic residue removal efficiency and measured interfacial shear forces. Initial results have shown that implementing an “overcutting” mechanism will decrease the overall shear force and significantly reduce the generation of secondary defects without sacrificing overall defect removal efficiency.

Amine-Based Chemistries for the Megasonic Removal of Alumina Nanoparticles from Oxidized Silicon Carbide

Increasing demand for improved Integrated Circuit (IC) technology has propelled the advancement from silicon as a semiconductor material to Wide Band Gap (WBG) materials (i.e., Silicon carbide (SiC), Gallium nitride (GaN)) due to their intrinsic properties (i.e., increased thermal stability, wear resistance, etc.). While these traits make WBGs ideal semiconductor materials, the Chemical Mechanical Planarization (CMP) process becomes difficult as these surfaces are more chemically inactive. To overcome this, the CMP process has shifted to incorporate more aggressive chemical and mechanical conditions (i.e., highly oxidative chemistries, increased shear force, etc.) to reach desired material removal rates (MRR). Traditional post-CMP (pCMP) cleaning processes combine high shear forces via a Polyvinyl Alcohol (PVA) brush with oxidative cleaning chemistries to remove CMP residue. This, however, results in secondary defect generation (i.e., scratches, pitting, brush debris) on the substrate surface. A low-shear force, non-contact cleaning process via megasonic energy is one way to combat secondary defect generation. The megasonic energy serves a dual function of reducing the substrate’s surface boundary layer, which allows for enhanced surface interaction with various cleaning solutions while also generating reactive oxygen species (ROS) that activate the chemistry. This work focuses on amine-based cleaning chemistries for oxidized SiC substrates. The introduction of the amine leads to a reduction of the oxidized surface, allowing for a weakened residue-substrate bond for an improved particle removal efficiency (PRE). Initial results have shown that amine-based standard clean 1 (SC-1) produced comparable results to previously utilized cleaning chemistries (i.e., Supramolecular chemistries), with a PRE of 11.4%. The PRE of SC-1 increases significantly in proportion to sonication power, with the highest PREs ranging between 90% to 96%. This work will provide insight into oxidized SiC surface behavior by incorporating other amine-based cleaning chemistries.

Improvement of Laser Damage Resistance of Fused Silica Using Oxygen-Aided Reactive Ion Etching

Reactive ion etching (RIE) with fluorocarbon plasma is a facile method to tracelessly remove the subsurface damage layer of fused silica but has the drawback of unsatisfactory improvement in laser damage resistance due to the induction of secondary defects. This work proposes to incorporate O2 into the CHF3/Ar feedstock of RIE to suppress the formation of secondary defects during the etching process. Experimental results confirm that both the chemical structural defects, such as oxygen-deficient center (ODC) and non-bridging oxygen hole center (NBOHC) defects, and the impurity element defects, such as fluorine, are significantly reduced with this method. Laser-induced damage resistance is consequently greatly improved, with the 0% probability damage threshold increasing by 121% compared to the originally polished sample and by 41% compared to the sample treated with conventional RIE.

Secondary defect coverage and functional reconstruction

Secondary reconstruction in trauma surgery is crucial for restoring both functional and esthetic results in patients with complex defects. Established reconstructive techniques in plastic surgery offer awide range of options for an effective treatment. This applies not only to covering large defects with free flaps but especially also for the functional reconstruction of bony, neural and musculotendinous impairments. Advances in the fields of microsurgery and 3D printing show innovative approaches to further improve the therapeutic options. Amultidisciplinary approach, requiring close collaboration between trauma and plastic surgeons, is necessary to optimize treatment plans and outcomes. The effective management of complications and qualified postoperative care are essential for the success of reconstructive measures.

Upregulation of cholesterol synthesis by lysosomal defects requires a functional mitochondrial respiratory chain

Mitochondria and lysosomes are two organelles that carry out both signaling and metabolic roles in cells. Recent evidence has shown that mitochondria and lysosomes are dependent on one another, as primary defects in one cause secondary defects in the other. Although there are functional impairments in both cases, the signaling consequences of primary mitochondrial dysfunction and lysosomal defects are dissimilar. Here, we used RNA sequencing to obtain transcriptomes from cells with primary mitochondrial or lysosomal defects to identify the global cellular consequences associated with mitochondrial or lysosomal dysfunction. We used these data to determine the pathways affected by defects in both organelles, which revealed a prominent role for the cholesterol synthesis pathway. We observed a transcriptional upregulation of this pathway in cellular and murine models of lysosomal defects, while it is transcriptionally downregulated in cellular and murine models of mitochondrial defects. We identified a role for the posttranscriptional regulation of transcription factor SREBF1, a master regulator of cholesterol and lipid biosynthesis, in models of mitochondrial respiratory chain deficiency. Furthermore, we found that retention of Ca2+ in lysosomes of cells with mitochondrial respiratory chain defects contributes to the differential regulation of the cholesterol synthesis pathway in the mitochondrial and lysosomal defects tested. Finally, we verified invivo, using a model of mitochondria-associated disease in Caenorhabditis elegans that normalization of lysosomal Ca2+ levels results in partial rescue of the developmental delay induced by the respiratory chain deficiency.

RENDIMIENTO Y CALIDAD FÍSICA DEL GRANO DE CAFÉ (Coffea arabica L.) VARIEDAD COSTA RICA 95

<p><strong>Background: </strong>Coffee is the second most consumed drink in the world, only after water. Quality characteristics are the most recurrent demands of consumers, which are of multifactorial origin and among which is agronomic management where soil nutrition or foliar nutrition of the plant is considered. <strong>Objective:</strong> To evaluate the yield and physical quality of the bean and cup of coffee (Coffea arabica L.) variety Costa Rica 95 by applying foliar fertilizer. <strong>Methodology: </strong>The evaluation was carried out in the La Laja community, municipality of Tlaltetela, Veracruz between 2018 and 2019. The age of the plantation used was four years and established with chalahuite shade (<em>Inga spuria</em> Humb. & Bonpl. ex Willd). The design used was a complete randomized block with two treatments (commercial control and treatment with foliar fertilization), with three repetitions each; the experimental unit consisted of a 300 m<sup>2</sup> plot and five coffee harvests were carried out, which were according to the number of flowerings during the 2018-2019 cycle. The physical evaluation was carried out according to the Official Mexican Standard NMX-F-162-SCFI-2008 and the NOM SCAA (2013). <strong>Results: </strong>The highest cherry yield and brix degrees were observed in the fertilized treatment with 12,897.8 kg ha<sup>-1</sup> and 20.06, respectively; in floats (waste) and snail (malformation), the highest weights were observed in the control treatment with 1,696.11 kg ha<sup>-1</sup> and 21.4 grams, respectively. The total sum of the sensory analysis was 81.3 and 85.2 for the treatments: control and fertilized, respectively. Higher numbers of grains were observed in sieves 19, 18 and 17 that are classified for the international scale. <strong>Implications: </strong>There is a positive effect of foliar fertilizer on the yield of cherry coffee and cup quality of Costa Rica coffee 95 and opens a range of possibilities to carry out a greater number of fertilization tests in the field, being able to compare an additional factor such as, for example, the climate (rain, drought, cold, heat, etc.). These studies should be carried out in the same area in which this experiment was carried out to compare whether the response shown is due solely to foliar fertilizer or there is an influence of climate, as well as management. It must be considered that the quality of coffee is multifactorial; in addition to environmental and genetic factors, there is management (nutrition, phytosanitary protection, pruning), harvest, among others. <strong>Conclusion: </strong>Foliar fertilization considerably improved the variables of interest evaluated in Costa Rica 95 coffee through the application of foliar fertilization, in addition to the fact that no primary or secondary defects were significantly present.</p>

A flexible, reusable and adjustable high-performance energy absorption system inspired by interlocking suture structures

Energy absorption systems play a very important role in impact protection under complex load conditions. However, traditional protective structures cannot adjust the mechanical properties on demand to accommodate variable load characteristics once manufactured. Therefore, inspired by the superior compression resistance of the diabolical ironclad beetle, a modular energy absorption system is developed by combining the efficient mechanical properties of thin-walled tubes and the robust connectivity of interlocking suture structures, which can be easily assembled from only bio-inspired tubes without external constraints. FEM simulations were performed to systematically investigate the static and dynamic mechanical properties of the developed system, and its crushing performance was demonstrated experimentally. Additionally, the influence of geometric parameters on the mechanical properties of the system has been investigated, and the insensitivity of secondary geometrical parameters and assembly defects has been verified, which shows that the system has a certain safety margin to avoid catastrophic accidents caused by fabrication defects. Moreover, the system exhibits excellent reusability under multi-impact load environments and its energy absorption capacity does not degrade after the primary impact. Furthermore, the system exhibits good designability thanks to the discrete modular structures, its mechanical properties can be tuned by stiffness design without affecting the energy absorption capacity, and its specific energy absorption can be effectively improved by lightweight design. This study provides a novel design strategy for the protection system applied in multiple complex environments.

Transcatheter Closure of Atrial Septal Defects with Absent Aortic Rim and the Predictors of Right Atrial Reverse Remodeling: 5 Years Experience in China

Plain Language SummaryAtrial septal defect (ASD) is a common congenital heart disease. The transcatheter approach is not recommended for absent aortic rim ASD. However, almost 30–40% of ASD patients in China are found to have an absent aortic rim with right atrial (RA) remodeling. We evaluated the safety and efficiency of transcatheter ASD closure in patients with an absent aortic rim and the predictors of RA reverse remodeling. No major operative complications occurred in all patients with the absence of an aortic rim and a normal edge. Without coronary heart disease, a lower plasma creatinine level, and less tricuspid regurgitation before the operation were the predictive factors for the reverse of RA remodeling after treatment.

Qualitative Model of Electrical Conductivity of Irradiated Semiconductor

There is constructed a qualitative model of the electrical conductivity of semiconductors irradiated with sufficiently high-energy particles. At certain conditions (irradiation temperature and dose, and subsequent thermal treatment), high-energy particles fluence, in addition to primary and secondary point radiation defects, forms a number of nano-sized disordered regions, highly conductive (“metallic”) compared to the semiconductor matrix. Their high total volume fraction can lead to the charge major carriers’ effective Hall mobility significantly exceeding that of the matrix. Due to elastic stresses created by these disordered inclusions, a high concentration of point radiation defects tends to form defective shells. In certain temperature ranges, such nanosized core-shell structures act as capacitors storing the electric charge sufficient for the Coulomb blockade of the major current carriers. Transformation of high-conductive inclusions into low-conductive (“dielectric”) ones manifests in a noticeable decrease in effective Hall mobility. The proposed model qualitatively explains all the experimental data available on single-crystalline n- and p-type silicon irradiated with high-energy electrons and protons and isochronously annealed.

Propeller Flap: A Feasible Flap for Distal Third of Leg Defects – Two Cases Done at the Plastic Surgery Unit of the Greater Accra Regional Hospital

Introduction: The traditional way of reconstructing soft tissue defects of the lower limb utilized muscle flaps as the ‘gold standard’ for Gustillo Anderson Grade III B fractures of the upper and middle thirds of the leg. Defects of the lower third of the leg are usually reconstructed with free flaps because of paucity and decreased reach of muscles. In resource constrained environments where free flaps are not routine with high failure rates, fasciocuataneous flaps are the only option left. We present our experience with the novel pedicled propeller perforator flaps for reconstruction of soft tissue defects in the lower limb. Case Presentation: Between June and October 2020, 2 consecutive patients - a 34-year-old male and a 51-year-old female, were referred for cover for their distal leg defects from the Orthopedics and trauma Unit. All patients were operated on under spinal anaesthesia. Perforators from posterior tibial and peroneal arteries respectively, were identified pre-operatively with hand-held doppler and the propeller-pattern skin paddle was designed around the perforator closest to defect. After elevation of flaps and skeletonization of perforators, they were then rotated (180 degrees) and inset into defects. Case 1 had whole flap (104 cm2) surviving with only minor marginal epidemiolysis at tip whilst the second flap (58.5cm2) had necrosis of only the business end of the flap but subsequently healed by secondary intention after serial dressings. Both had secondary defects proximally after the rotation, which were skin grafted with 100% take. Conclusion: Propeller flap in our experience, is a feasible versatile option for reconstruction of soft tissue defects in the distal third of the leg.

Suppressing Element Inhomogeneity Enables 14.9% Efficiency CZTSSe Solar Cells.

Kesterites, Cu2ZnSn(SxSe1- x)4 (CZTSSe), solar cells suffer from severe open-circuit voltage (VOC) loss due to the numerous secondary phases and defects. The prevailing notion attributes this issue to Sn-loss during the selenization. However, this work unveils that, instead of Sn-loss, elemental inhomogeneity caused by Cu-directional diffusion toward Mo(S,Se)2 layer is the critical factor in the formation of secondary phases and defects. This diffusion decreases the Cu/(Zn+Sn) ratio to 53% at the bottom fine-grain layer, increasing the Sn-/Zn-related bulk defects. By suppressing the Cu-directional diffusion with a blocking layer, the crystal quality is effectively improved and the defect density is reduced, leading to a remarkable photovoltaic coversion efficiency (PCE) of 14.9% with a VOC of 576mV and a certified efficiency of 14.6%. The findings provide insights into element inhomogeneity, holding significant potential to advance the development of CZTSSe solar cells.

Patterns of primary and secondary defects associated with non-syndromic cleft lip and palate: An epidemiological analysis in a Kenyan population.

Cleft lip and palate deformities substantially burden individuals and families, particularly in low-income communities. However, a comprehensive understanding of the patterns and distribution of these deformities in Kenya remains limited. This retrospective cross-sectional study analyzed 647 clinical records from the BelaRisu Foundation registry in Kenya, spanning 2018-2022. After meticulous record verification and data extraction, cleft pattern modeling was used to analyze each case. Data were imported to SPSS version 29.0 and descriptive statistics were calculated, which included means, ranges, frequencies, percentages, and standard deviations. Additionally, a comparative analysis between genders was conducted. The findings revealed a higher average age of presentation compared with previous studies in Kenya, along with a greater susceptibility of males to cleft lip and palate defects overall. Noteworthy disparities in case distribution across provinces were observed. Cleft lip emerged as the most observed primary defect, while palatal fistulae constituted the most frequent secondary defect. Interestingly, while some results aligned with global trends, others diverged significantly from the existing literature, warranting further exploration and investigation. These findings shed light on the unique patterns and distribution of cleft lip and palate deformities in Kenya, highlighting the need for targeted interventions and support systems.

NovoSorb® biodegradable temporising matrix (BTM) in the reconstruction of cutaneous malignancies in a major cancer centre: a case series.

Non-graftable or composite defect reconstruction represents a major challenge to the reconstructive surgeon, with many wounds requiring local flap or free microvascular tissue transfer approaches. The recent advent of synthetic skin substitutes such as Biodegradable Temporizing Matrix (BTM) have revolutionized the management of complex defects including those caused by burns, trauma and infection, with low-morbidity and low-complexity surgery. However, limited data exist supporting their use in cancer reconstruction in Australia. We performed a prospective cohort study of patients undergoing cancer resection and reconstruction with BTM between February 2021 and February 2023 in our institution. Reported outcomes included matrix integration, infection, and return to theatre. Twelve patients underwent reconstruction of primary or secondary defects following cancer resection during this period. Eight patients were male, four female, mean age at surgery was 70 years. Pathology resected included squamous cell carcinoma (SCC) and melanoma of the head and neck, sarcoma resection of the lower limb, and osteoradionecrosis (ORN) of the scalp. T-stage of primary tumours ranged from T2 to T4 and one in-transit metastasis of melanoma. Four patients were treated with radiotherapy, two of whom received postoperative radiotherapy (PORT) and two who received neoadjuvant radiotherapy, three additional patients had an intervention to a previously irradiated wound bed for recurrence or ORN. Overall matrix integration was 83% (10/12), with a 50% integration rate (2/4) observed in the post-radiotherapy group, requiring return to theatre for alternative reconstructive approaches. We report our experience with a synthetic dermal matrix (BTM) in cancer reconstruction, the largest cohort of this type in the Australian literature. BTM represents an exciting reconstructive tool for the cancer reconstructive surgeon, with a high rate of success and low morbidity.

Vacancy‐Type Defects and Their Trapping/Detrapping of Charge Carriers in Ion‐Implanted GaN Studied by Positron Annihilation

Annealing behaviors of vacancy‐type defects in ion‐implanted GaN are studied by positron annihilation. Mg+ and N+ ions are implanted to obtain 700 nm deep box profiles with Mg and N concentrations of 1 × 1018 cm−3, and the samples are annealed using an ultrahigh‐pressure annealing system. For as‐implanted samples, the major defect species is identified as Ga‐vacancy (VGa)‐type defects. For N‐implanted GaN, the size of the vacancies increases as the annealing temperature increases up to 1100 °C and then shrank above 1200 °C. This behavior is attributed to recombinations between N‐vacancy (VN)‐type defects and excess N. For Mg‐implanted GaN, the major defect species after annealing above 1000 °C is vacancy clusters such as (VGaVN)3. Some of them act as nonradiative recombination centers for blue and ultraviolet luminescence. Their energy levels corresponding to the transition from positive to neutral are located between 2.6 eV above the valence band maximum and the conduction band minimum. The thermal activation process of electron detrapping from the vacancy clusters is also studied. For Mg‐implanted GaN, one of the major secondary defects is collapsed vacancy disks forming dislocation loops. They are eliminated by additional N implantation, which is associated with vacancy agglomerations under the annealing in VGa‐rich condition.

Failure analysis of welded joint with multiple defects by extended Finite Element Method and Engineering Critical Analysis

Failure analysis of welded joint with multiple defects was performed taking into account the effect of all defects, not just a dominant one. Four cases of multiple defects in welded joint under the uniaxial tensile loading were investigated using extended Finite Element Method. Two-dimensional Finite Element Models were made according to the tensile specimens with initial crack located in a critical area of welded joint. For each multiple defects case, numerical simulation was performed with three initial crack depth. Engineering Critical Analysis was made using Failure Assessment Diagrams for each defect that was determined as critical for its welded joint case. Numerical simulation showed that the geometry of the most prominent one from a point of view of structural integrity. It was concluded that the vertical misalignment in combination with a secondary defect, had the most adverse effect which can lead to failure of welded structure.