Mechanical Defects Research Articles

A novel dynamic structural adaptive multivariable grey model and its application in China's solar energy generation forecasting

Accurately predicting China's solar energy generation is crucial for energy planning and environmental protection. However, the nonlinearity and complexity of the data pose challenges to prediction. This article proposes a dynamic structural adaptive multivariate grey model to overcome these challenges. The model constructs a dynamic nonlinear correction function with an uncertain structure that can adaptively adjust to the data characteristics. Additionally, the Gaussian function is utilized to derive the time response function, overcoming the mechanism defects present in traditional multivariate grey models. The whale optimization algorithm is applied to optimize the background value of the model, improving accuracy. The model is compatible with 14 classical models via parameter changes and has strong compatibility. The results show that the fitting error and test error of the model are 0.23 % and 1.95 % respectively, which is significantly better than the other 11 methods, indicative of strong robustness and accuracy. The forecast indicates that China's solar energy generation will experience a consistent upward trajectory from 2023 to 2030, with an average annual growth rate of 12.11 %. This study significantly contributes to the advancement of the theory of multivariate grey dynamic prediction and provides essential data support for strategic planning within China's solar power industry.

An understanding of the segregation and migration mechanism of point defects in tungsten grain boundaries: An atomic scale simulation

In this study, molecular dynamics (MD) simulations are employed to investigate the interactions between point defects and grain boundaries (GBs) in tungsten. Firstly, the segregation energy of vacancies (Vs) and self-interstitial atoms (SIAs) to GBs is examined. The results indicate that both Vs and SIAs tend to segregate towards GBs. Notably, the different types of GBs exhibit varying attraction to Vs and SIAs. The interaction radius is applied to investigate the degree of segregation, which is a significant index of GBs’ attraction to Vs and SIAs. The segregation radius of SIAs is typically larger than that of Vs. High-angle grain boundaries (HAGBs) show strong segregation for SIAs, facilitating the aggregation at GBs. Additionally, elastic theory is applied to qualitatively discuss the factors influencing the segregation energy distribution. The differences in atomic free volume caused by hydrostatic stress and the lattice distortion induced by point defects lead to Vs and SIAs occupying different sites. Finally, the nudged elastic band (NEB) method is employed to study the migration of Vs and SIAs near GBs, revealing that migration energy barriers for Vs and SIAs in GBs are much lower than in bulk. GBs facilitate the migration of point defects. Low-angle grain boundaries (LAGBs) present a higher energy barrier for V migration. Vs tend to occupy the compressive region, while SIAs tend to occupy the tensile region. Particularly, in comparison to Vs, SIAs are more likely to segregate to GBs due to higher binding energy, wider interaction radius, and extremely lower diffusion energy barrier. This provides some insights into the segregation and migration of point defects in GBs.

Formation Mechanism and Prevention of Cu Undercut Defects in the Photoresist Stripping Process of MoNb/Cu Stacked Electrodes

The Cu undercut is a recently discovered new defect generated in the wet stripping process of MoNb/Cu gate stacked electrodes for thin-film transistors (TFTs). The formation mechanism and preventive strategy of this defect were identified and investigated in this paper. The impact of stripper concentration and stripping times on the morphology and the corrosion potential (Ecorr) of Cu and MoNb were studied. It is observed that the undercut is Cu tip-deficient, not the theoretical MoNb indentation, and the undercut becomes severer with the increase in stripping times. The in-depth mechanism analysis revealed that the abnormal Cu undercut was not ascribed to the galvanic corrosion between MoNb and Cu but to the local crevice corrosion caused by the corrosive medium intruding along the MoNb/Cu interface. Based on this newly found knowledge, three possible prevention schemes (MoNiTi (abbreviated as Mo technology development (MTD) layer/Cu), MoNb/Cu/MTD, and MoNb/Cu/MoNb) were proposed. The experimental validation shows that the Cu undercut can only be completely eliminated in the MoNb/Cu/MTD triple-stacked structure with the top MTD layer as a sacrificial anode. This work provides an effective and economical method to avoid the Cu undercut defect. The obtained results can help ensure TFT yield and improve the performance of TFT devices.

Mechanisms of Controllable Growth and Ohmic Contact of Two-Dimensional Molybdenum Disulfide: Insight from Atomistic Simulations.

ConspectusTwo-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), in particular molybdenum disulfide (MoS2), have recently attracted huge interest due to their proper bandgap, high mobility at 2D limit, and easy-to-integrate planar structure, which are very promising for extending Moore's law in postsilicon electronics technology. Great effort has been devoted toward such a goal since the demonstration of protype MoS2 devices with high room-temperature on/off current ratios, ultralow standby power consumption, and atomic level scaling capacity down to sub-1-nm technology node. However, there are still several key challenges that need to be addressed prior to the real application of MoS2-based electronics technology. The controllable growth of wafer-scale single-crystal MoS2 on industry-compatible insulating substrates is the prerequisite of application while the currently synthesized MoS2 films mostly are polycrystalline with limited sizes of single-crystal domains and may involve metal substrates. The precise layer-control is also very important for MoS2 growth since its electronic properties are layer-dependent, whereas the layer-by-layer growth of multilayer MoS2 dominated by the van der Waals (vdW) epitaxy leads to poor thickness uniformity and noncontinuously distributed domains. High density up to 1013 cm-2 of sulfur vacancies (SVs) in grown MoS2 can cause unfavorable carrier scatting and electronic properties variations and will inevitably disturb the device performance. The dangling-bond-free surface of MoS2 gives rise to an inherent vdW gap at metal-semiconductor (M-S) contact, which leads to high electrical resistance and poor current-delivery capability at the contact interface and thereby substantially limits the performances of MoS2 devices.In this Account, we briefly review recent experimental and theoretical attempts for addressing the aforementioned challenges and present our own insights from atomistic simulations. We theoretically revealed the vital role of substrate steps for guiding unidirectional nucleation of monolayer MoS2 and uniform nucleation and edge-aligned growth of bilayer MoS2 by advanced simulations. The established thermodynamic mechanisms have successfully directed the experimental works on the controllable growth of 2 in. single-crystal monolayer and centimeter-scale uniform bilayer MoS2. The postgrowth repair mechanism of SV defect in MoS2 via thiol chemistry treatment has been theoretically explored with the consideration of side reaction of surface functionalization to help experimentally reduce SV defect density by 75%. Beyond the atomic level understanding, theoretical simulations proposed the electronic states hybridization mechanism across the semimetal-MoS2 vdW interface, thereby guiding experimental effort for realizing Ohmic contact at the MoS2-Sb(0112) vdW interface with record-low contact resistance.These advances provide a sound basis with an atomic-level understanding for addressing the related issues. However, there are still notable gaps in terms of system size and time scale of dynamics between atomistic simulations and experimental observations for the studies of MoS2 growth and interfaces. The combination of multiscale simulations and artificial intelligence technology is expected to narrow these gaps and provide a more insightful understanding of the controllable growth and interfacial properties modulation of MoS2. We conclude the Account with the standing challenges and outlook on future research directions from the theoretical perspective.

Effect of Eu Ions Concentration in Y2O3-Based Transparent Ceramics on the Electron Irradiation Induced Luminescence and Damage

Eu3+-doped Y2O3-based luminescent materials can be used as a scintillator for electron or high energy β-ray irradiation, which are essential for applications such as electron microscopy and nuclear batteries. Therefore, it is essential to understand their defect mechanisms and to develop materials with excellent properties. In this paper, Y2O3-based transparent ceramics with different Eu3+ doping concentrations were prepared by solid-state reactive vacuum sintering. This series of transparent ceramic samples exhibits strong red emission under electron beam excitation at the keV level. However, color change appears after the high-energy electron irradiation due to the capture of electrons by the traps in the Y2O3 lattice. Optical transmittance, laser-excited luminescence, X-ray photoelectron spectroscopy (XPS), and other analyses indicated that the traps, or the color change, mainly originate from the residual oxygen vacancies, which can be suppressed by high Eu doping. Seen from the cathodoluminescence (CL) spectra, higher doping concentrations of Eu3+ showed stronger resistance to electron irradiation damage, but also resulted in lower emissions due to concentration quenching. Therefore, 10% doping of Eu was selected in this work to keep the high emission intensity and strong radiation resistance both. This work helps to enhance the understanding of defect formation mechanisms in the Y2O3 matrix and will be of benefit for the modification of scintillation properties for functional materials systems.

Functional germline variants in DNA damage repair pathways are associated with altered survival in adults with glioma treated with temozolomide.

Temozolomide (TMZ) treatment has demonstrated, but variable, impact on glioma prognosis. This study examines associations of survival with DNA repair gene germline polymorphisms among glioma patients who did and did not have TMZ treatment. Identifying genetic markers which sensitize tumor cells to TMZ could personalize therapy and improve outcomes. We evaluated TMZ-related survival associations of pathogenic germline SNPs and genetically predicted transcript levels within 34 DNA repair genes among 1504 glioma patients from the UCSF Adult Glioma Study and Mayo Clinic whose diagnoses spanned pre- and post-TMZ eras within the major known glioma prognostic molecular subtypes. Among those who received TMZ, 5 SNPs were associated with overall survival, but not in those who did not receive TMZ. Only rs2308321-G, in MGMT, was associated with decreased survival (HR=1.21, p=0.019) for all glioma subtypes. Rs73191162-T (near UNG), rs13076508-C (near PARP3), rs7840433-A (near NEIL2), and rs3130618-A (near MSH5) were only associated with survival and TMZ treatment for certain subtypes, suggesting subtype-specific germline chemo-sensitization.Genetically predicted elevated compared to normal brain expression of PNKP was associated with dramatically worse survival for TMZ-treated patients with IDH-mutant and 1p/19q non-codeleted gliomas (p=0.015). Similarly, NEIL2 and TDG expressions were associated with altered TMZ-related survival only among certain subtypes. Functional germline alterations within DNA repair genes were associated with TMZ sensitivity, measured by overall survival, among adults with glioma, these variants should be evaluated in prospective analyses and functional studies.

Evaluation of tribological parameters for boron carbide and graphite infused aluminium hybrid composite fabricated by stir casting technique

The present work focuses on suggesting Gr as a valuable self-lubricating reinforcement for hybrid composite samples and offering a minimum wear rate for sliding pairs with fewer mechanical surface defects at the same time. A series of samples were fabricated using the route by stir casting method considering B4C and Gr as the two reinforcements. The morphology of the sample has been studied using the X-ray diffraction graphs, Energy dispersive X-ray analysis and Scanning electron imaging stating the homogeneity of reinforcement in various composite cast. The theoretical and experimental density of the series of samples has been studied and compared stating the low porosity of the samples fabricated. A maximum wear rate (Wr) of 0.351 × 10−4 mm3/m. was found for pure aluminium sample against EN31 steel disc with 0.053 as friction coefficient (µ). Wr was somehow seen to reduce up to 0.286 × 10−4 mm3/m for Al-B4C composite with µ of 0.48. For hybrid samples, the wear rate was further seen to improve to 0.187 × 10−4 mm3/m for Al-B4C and Gr 2.0% weight with µ of 0.38. Least Wr was found for composite having Gr 3.5% weight, of 0.149 × 10−4 mm3/m. with µ of 0.36. SEM images of the worn surface give evident results for delamination and crack formation on the pin face for the pure-Al sample. Taguchi-ANOVA analysis has been carried out showing the valid contribution of pin type, load and sliding speed on Wr and friction coefficient as the P-value lies below 0.05 for input parameters considering the 95% confidence level of the model developed. An F-value of 44.57 with R2 of 0.895 is developed for Wr model and an F-value of 54.2 with R2 of 0.934 for the µ model.

Formation mechanism of pore defects and surface ripples under different process parameters via laser powder bed fusion by numerical simulation and experimental verification

Formation mechanism of pore defects and surface ripples under different process parameters via laser powder bed fusion by numerical simulation and experimental verification

Assessment of Serum CXCL10 in the Sera of Patients with Active Vitiligo before and after Treatment with Oral Mini-Pulse Steroid Therapy versus Parenteral Corticosteroids Therapy: An Interventional Prospective Clinical Study

Abstract Background Vitiligo is the most common depigmenting skin disorder. The complexity of its pathogenesis, influenced by genetic factors, oxidative stress and abnormal cell adhesion that collectively impact melanocyte survival and trigger immune system attacks, resulting in melanocyte death. Melanocytes in vitiligo are believed to exhibit genetic susceptibility and defects in cellular mechanisms, such as defects in autophagy, that reduce their ability to resist oxidative stress. leading to increased expression of the pro-inflammatory protein HSP70. The low expression of adhesion molecules, such as DDR1 and E-cadherin, accelerates melanocyte damage and antigen exposure. Consequently, autoimmune attacks centered on IFN-γ-CXCR9/10-CXCR3-CD8+ T cells are initiated, causing vitiligo Objective To study the difference between weekend oral mini-pulse steroids or depot triamcinolone acetonide injection given every 3 weeks in stabilization of active vitiligo by measuring serum level of CXCL10 Methods This study was an interventional prospective clinical trial study that included 46 cases with active vitiligo divided as 23 cases in group A received low dose oral minipulse dexamethasone 2.5 mg on two consecutive days per week and 23 cases in group B received IM triamcinolone acetonide injection every 3 weeks. Both groups were evaluated at baseline, 4,8 and 12 weeks using activity scores as VIDA, VASI, VES, Score/7and at laboratory level by measuring serum CXCL10 Results When comparing both regimens as regarding halting vitiligo activity, both treatments could stop disease activity as assessed by activity scores and serum level of CXCL10 this effect was as early as week 4 in both groups with no statistically significant difference Conclusion We concluded that the level of CXCL10 was elevated in active vitiligo patients and decreased after the treatment with systemic steroids both low dose oral minipulse dexamethasone and Triamcinolone acetonide intramuscular injection. These findings may point to the role of CXCL10 in the activity of vitiligo which should be furtherly investigated

Type-Specific Impacts of Protein Defects in Pathogenic NFKB2 Variants: Novel Clinical Findings From 138 Patients

BackgroundThe non-canonical NF-κB2 pathway is integral in regulating immunological responses, supervising immune function, development and homeostasis. NFKB2 encodes the cytoplasmic precursor p100, which undergoes processing of its inhibitory C-terminal half to generate p52. Impeding C-terminal defects are well established to cause PID. In contrast, the mechanism of truncating N-terminal defects remains obscure. ObjectiveWe characterized clinical phenotypes associated with three distinct protein-defect types: (I) early truncations: typically occurring N-terminal relative to the NLS and affecting the RHD, predicting p100 expression to be halved and subsequent p52 generation by processing to be diminished (II) Central truncations: mainly affecting the ARD and predicting immediate expression of p52-like proteins and a 50% reduction of p100; and (III) C-terminal phosphorylation-/ubiquitination domain defects: causing expression of non-processable p100 with retained IκB-like activity and subsequently reducing generation of p52. MethodsWe performed literature research on PubMed, Clinvar and HGMD collecting clinical and immunological data on NFKB2 patients, focusing on comparing protein-defect-specific impacts. ResultsThe highest prevalence of early-onset PID and antibody deficiency occurred in the CTD-defect group. Additionally, endocrinological abnormalities and T-cell-mediated autoimmunity were common and frequently required immunosuppression. An extensive immunological workup revealed patients with C-terminal defects to have pan-hypogammaglobulinemia and reduced specific antibody responses and markedly impaired B cell differentiation, but normal to elevated T cell counts. In contrast, pathogenic NFKB2 variants causing central or early truncating protein defects were only partially penetrant, with ameliorated symptoms and diminished T-cell-mediated autoimmunity. ConclusionOur work defines a clear genotype-phenotype correlation for NFKB2 mutations.

Study on the formation and corrosion mechanism of black spot defects on the surface of industrial continuously hot-dip galvanized Zn-2Al-1.5Mg coating

Study on the formation and corrosion mechanism of black spot defects on the surface of industrial continuously hot-dip galvanized Zn-2Al-1.5Mg coating

Application of mechanical crack defect detection based on thermal energy parameter simulation and sensing images in product process design

Mechanical equipment in the process of operation, often due to material fatigue, environmental changes and other factors crack, if not timely detection, may lead to serious safety accidents. Therefore, this paper constructs a new crack defect detection method through thermal parameter simulation technology and image data obtained by sensors to improve the accuracy and efficiency of detection. The thermal parameters were simulated, the surface temperature of the material was monitored by thermal imaging technology, and the potential cracks were identified by analyzing the heat flow distribution. Image processing algorithm is used to extract the key features of the sensor image and further analyze the cracks. In the experiment, the crack defects under different materials and process conditions were verified to evaluate the effectiveness of the method. The experimental results show that the detection method based on thermal parameter simulation combined with sensor image processing can effectively identify cracks of different sizes and shapes, and has high accuracy and stability. Compared with traditional detection methods, this method shows significant advantages in detecting small cracks. The detection technology of thermal energy parameter simulation combined with sensor image provides a new idea for the identification of mechanical crack defects and has a good application prospect.

Computer Simulation and Simulation of Mechanical and Electrical Equipment based on Artificial Intelligence Algorithms

The computer in mechanical and electrical equipment can now detect equipment faults through simulation thanks to the advancement of artificial intelligence (AI) technology, which makes it convenient to monitor mechanical and electrical equipment. This paper begins with a quick introduction to Agent and the Agent system, explains how Agent is applied in the current context, then analyzes the hierarchical fault diagnostic model, identifies its flaws, and suggests improvement techniques. To increase the model’s accuracy and speed of operation, the contract net model and D-S (Dempster-Shafer) evidence theory are then incorporated. Finally, simulation experiments are used to confirm the accuracy and consistency of this model. According to the experimental findings, this optimization model runs at a pace that is noticeably faster than that of other models when subjected to the same workload, demonstrating the model’s efficacy. Models 1, 2, and 3 are put side by side to demonstrate how clearly multi-task processing may cut down on the model’s running time. In the second experiment, samples of mechanical and electrical equipment defect data are taken from two groups. The results of the comparative experiments demonstrate that the optimized model in this work can be reliable up to a maximum of 0.91 and a minimum of 0.63. It is demonstrated that the model in this work is rational by the fact that among the four types of fault prediction, the optimized model’s reliability is significantly greater than the traditional model’s. The research described in this publication therefore has some reference value for computer simulation of electromechanical equipment.

Effect of the N-doping concentration on the formation of the wide carrot defect in 4H-SiC homoepitaxial layer grown by trichlorosilane (TCS) as silicon precursor

The effect of epilayer growth system, growth rate and N-doping concentration on the formation of the wide carrot defects in 4H-SiC homoepitaxial layer was investigated in this work. We found that the wide carrot defect formed on 4H-SiC epilayer only with low N-doping concentration of 5 × 1014 cm−3 grown by the SiHCl3+C2H4+H2 (TCS) system, which is different with the previous reports on the SiH4+C3H8+H2 growth system that can form such defect regardless of N-doping concentration. Besides, such wide carrot defect was never found on high speed growth of epilayer surface grown by TCS growth system. The morphology and structure of wide carrot defects were characterized by optical microscope (OM), micro-photoluminescence (PL) spectroscopy, atomic force microscope (AFM) and molten KOH etching. We speculate that the amount of wide carrot defects is related with the basal plane dislocations (BPDs) density which depends on the epitaxial growth system, growth rate of epilayer and the N-doping concentration. The formation mechanism and elimination methods of these wide carrot defects were proposed.

Exploring structural and mechanical properties of SiNx thin films on SiO2 substrate via molecular dynamics simulations

Silicon nitride (SiNx) and silicon dioxide (SiO2) are crucial in microelectronic and photonic devices, where their interface affects performance and reliability. This study explores the effects of growth conditions on the mechanical properties of amorphous SiNx films on SiO2 substrates using molecular dynamics simulations. We address key integration challenges, focusing on mechanical residual stresses and surface defects. We assess the impact of substrate temperature, atom bombardment energy, and SiNx composition on intrinsic stress, Young’s modulus, and film toughness, focusing on the film’s susceptibility to failure and cracking. Our analysis includes deposition simulations at room temperature and 1100 K, with kinetic energies from 0.01 eV to 1 eV per atom. We investigate SiNx compositions from Si-rich to N-rich compositions to evaluate their effect on mechanical properties. The Tersoff potential for multi-body interactions facilitates a comprehensive examination of factors influencing mechanical stress and cracking. We numerically reproduced SiNx films with intrinsic stress values from 1 GPa tensile to −0.6 GPa compressive by varying deposition energy. For tensile films, we calculated critical thicknesses at which cracking occurs, from 200 nm to 4 µm. These insights refine deposition techniques, enhance mechanical durability, and support the development of reliable SiN optical platforms for photonic integrated circuits.

Smart Window with Reversible and Instantaneous Photoluminescence based on Microsphere Structure.

A smart window that dynamically regulates light transmittance is crucial for modern life end-users and promising for on-demand optical devices. The advent of three-dimensional (3D) photonic crystal microspheres has enriched the functions of a smart window. However, the smart window formed by polymer microspheres encounters poor mechanical strength and microstructural defects. Herein, to solve this limitation, we report the microsphere-based smart window composed of tightly packed cross-linked polymer microspheres (as a precursor) containing organic photochromic dyes, followed by compression under a high elastic state. When excited under an ultraviolet supply, our smart window showed a rapid and reversible fluorescent photoluminescence without fatigue (50 cycles). Moreover, the bulk devices with a microsphere cross-linked network structure enable excellent mechanical strength (hardness reached 0.158 GPa) and visible-light transparency. Interestingly, a QR code can be recognized under visible light exposure but not under ultraviolet light exposure because of photoluminescence of the smart window. Our method generally provided a paradigm for various amorphous polymers, which can be regarded as a simple and effective approach to build a versatile strategy to introduce an ideal marketplace with economic and community benefits.

Characterization Study of Deep-Level Defect Spatial Distribution, Emission Mechanisms, and Structural Identification

Abstract The characterization of defects in semiconductor materials and devices is crucial for enhancing the performance and reliability of semiconductor products. This tutorial review focuses on Deep Level Transient Spectroscopy (DLTS) as the primary analytical tool, thoroughly discussing its distinct advantages in deep-level defect characterization. However, it is unable to reveal the concentration-depth distribution of deep-level defects, neglects the dependency of carrier emission rates on the electric field, and fails to accurately identify defect structures.
To overcome these limitations, two enhanced DLTS techniques have been developed to extend the capabilities of DLTS. These enhancements include the utilization of graded fill pulse technology to accurately map defect distributions at various depths within devices, facilitating individual defect characterization across different layers of multilayered structures; the application of varying electric field strengths to samples to delve into the intricate physical mechanisms of defects during carrier emission processes; and the adjustment of the duration of electric pulse injection to monitor signal growth trends, deducing the microstructure of defects. The paper integrates research findings from a wide array of field experts, meticulously outlines a description of how to obtain the depth distribution of defect concentration in devices, furnishes quantitative criteria for both the Poole-Frenkel effect and phonon-assisted tunneling mechanisms of carrier emission, and provides specific examples for distinguishing between interface states/bulk defects and point defects/extended defects. This enhances both the theoretical and practical knowledge in this field. The advanced DLTS techniques outlined provide crucial guidance for defect characterization and performance optimization in semiconductor devices with new structures and materials.

Effect of Deep Cryogenic Treatment on the Mechanical Properties and Defect Tolerance of Selective-Laser-Melted 316L Stainless Steel

Effect of Deep Cryogenic Treatment on the Mechanical Properties and Defect Tolerance of Selective-Laser-Melted 316L Stainless Steel

Molecular mechanisms for DNA methylation defects induced by ICF syndrome-linked mutations in DNMT3B.

DNA methyltransferase 3B (DNMT3B) plays a crucial role in DNA methylation during mammalian development. Mutations in DNMT3B are associated with human genetic diseases, particularly immunodeficiency, centromere instability, facial anomalies (ICF) syndrome. Although ICF syndrome-related missense mutations in the DNMT3B have been identified, their precise impact on protein structure and function remains inadequately explored. Here, we delve into the impact of four ICF syndrome-linked mutations situated in the DNMT3B dimeric interface (H814R, D817G, V818M, and R823G), revealing that each of these mutations compromises DNA-binding and methyltransferase activities to varying degrees. We further show that H814R, D817G, and V818M mutations severely disrupt the proper assembly of DNMT3B homodimer, whereas R823G does not. We also determined the first crystal structure of the methyltransferase domain of DNMT3B-DNMT3L tetrameric complex hosting the R823G mutation showing that the R823G mutant displays diminished hydrogen bonding interactions around T775, K777, G823, and Q827 in the protein-DNA interface, resulting in reduced DNA-binding affinity and a shift in sequence preference of +1 to +3 flanking positions. Altogether, our study uncovers a wide array of fundamental defects triggered by DNMT3B mutations, including the disassembly of DNMT3B dimers, reduced DNA-binding capacity, and alterations in flanking sequence preferences, leading to aberrant DNA hypomethylation and ICF syndrome.

The role of erythropoietin-loaded hydrogel versus adipose derived stem cell secretome in the regeneration of tongue defects

BackgroundTongue defects have several etiologies and significantly affect the quality of life. This study was conducted to compare the regenerative potential of erythropoietin (EPO)-loaded hydrogel and adipose derived stem cell (ADSC) secretome on tongue dorsum defects focusing on the role of anti-inflammatory M2 macrophage phenotype.MethodsRats were subjected to induction of mechanical circular defects on the dorsal surface of the tongue, then divided into three groups; Group I (control): received 0.1 ml phosphate buffered saline, Group II (EPO): received 5000 U/kg EPO-hydrogel, and Group III (ADSC-Secretome): received 0.1 ml ADSC-Secretome. Treatments were injected circumferentially around wound margins after induction. Seven and fourteen days after treatment, specimens were obtained and processed for histological and immunohistochemical staining followed by the relevant histomorphometric and statistical analyses.ResultsSeven days after treatment, groups II and III presented defects with some epithelial regeneration at the lateral margins, while the center of the defect showed granulation tissue with much inflammatory cells. The base of the defects showed some muscle fibers and new blood vessels, however group III showed more enhanced neovascularization. Fourteen days after therapeutic intervention, group II defects were completely covered with epithelium showing a thin keratin layer with regular rete pegs interdigitating with the underlying connective tissue papillae, but tongue papillae were not restored. Group III expressed much better healing with developing filiform papillae. The connective tissue showed more vascularity and well-arranged muscle bundles. Both treated groups showed a significant decrease in defect depth and significant increase in anti-inflammatory macrophages compared to the control group at both time intervals, however there was no significant difference between the two treated groups.ConclusionBoth treatments showed promising and comparable results in the treatment of tongue defects reducing inflammation and restoring tongue histological architecture with significant upregulation of M2 macrophage.