Complex Defects Research Articles

Influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr

We report the influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr through superexchange involving Mn–O–Mn, Fe–O–Fe, and Cr–N–Cr atomic configurations. Density Functional Theory (DFT) calculations demonstrated that these configurations originate within VGa-ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}-{O}_{\ ext{N}}$$\\end{document} complex defects by incorporating Mn2+, Fe2+, and Cr3+ ions into gallium vacancies (VGa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}$$\\end{document}) sites promoted by the presence of oxygen as a substitutional impurity (ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${O}_{\ ext{N}}$$\\end{document}). These co-doped GaN microstructures were synthesized using the thermal evaporation method. Cathodoluminescence (CL) and photoluminescence (PL) measurements confirmed the presence of VGa-ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}-{O}_{\ ext{N}}$$\\end{document} complex defects in all GaN-grown samples. X-ray photoelectron spectroscopy (XPS) measurements confirmed the successful incorporation of Mn2+, Fe2+, and Cr3+ ions in GaN samples. SQUID measurements demonstrated room-temperature ferromagnetism with respective saturation magnetization (Ms) and coercive field (Hc) values of ± 1.5 × 10−5 emu and 4 mT for GaN:O,Mn, ± 4.4 × 10−5 emu and 2.6 mT for GaN:O,Fe, and ± 1.7 × 10−5 emu and 2.6 mT for GaN:O,Cr.

Cortical Alterations Associated with Executive Function Deficits in Youth with a Congenital Heart Defect

Abstract Adolescents and young adults born with a complex congenital heart defect (CHD) are at risk for executive function (ExF) impairments, which contribute to the psychological and everyday burden of CHD. Cortical dysmaturation has been well described in fetuses and neonates with CHD and early evidence suggests that cortical alterations in thickness, surface area, and gyrification index are non-transient and can be observed in adolescents with CHD. However, cortical alterations have yet to be correlated with ExF deficits in youth with CHD. This study aims to use a data-driven approach to identify the most important cortical features associated with ExF deficits in adolescents and young adults with CHD. To do so, we combined two comparable datasets acquired at the Research Institute of the McGill University Health Centre and the University Children’s Hospital Zurich each including both youth with CHD and healthy controls. For each participant, a high-resolution T1-weighted magnetic resonance image, a self-reported ExF assessment (the Behaviour Rating Inventory of Executive Function— Adult Scale), and their clinical and demographic characteristics were available. Corticometric Iterative Vertex-Based Estimation of Thickness (CIVET) was used to extract cortical thickness, cortical surface area, and local gyrification index measures. Using orthogonal projective non-negative matrix factorization (OPNMF), we identified non-overlapping spatial components that integrate cortical thickness, cortical surface area, and local gyrification index and capture structural covariance across these features. Behavioural partial least squares correlation (bPLS) analysis was then used to compute correlations between the individual variability in the OPNMF covariance patterns and ExF outcomes for each subject. A total of 56 youth with CHD who underwent cardiopulmonary bypass surgery before three years of age and 56 age- and sex-matched healthy controls were included in our analyses. Cortical grey matter volume, cortical thickness, and cortical surface area were found to be significantly reduced in CHD patients compared to controls. OPNMF identified 12 stable cortex-wide components summarizing the inter-subject variability in cortical thickness, cortical surface area, and local gyrification index. bPLS revealed two significant latent variables (LV) accounting for a total of 82.8% of the variance in the sample, each describing distinct patterns between the brain and cognitive data. LV1 summarized a pattern of belonging to the CHD group, worse scores on most BRIEF-A scales, younger age at MRI, and female sex. This pattern was associated with increased cortical thickness, local gyrification index, and decreased cortical surface area in several OPNMF components. Finally, we identified a positive relationship between the LV1 brain-behaviour pattern and total aortic cross-clamp time in the CHD group, indicating that longer aortic cross-clamp time was associated with worse neurodevelopmental outcomes. In this study, we uncover novel multivariate relationships between ExF and alterations in cortical thickness, surface area, and local gyrification index in adolescents and young adults with CHD using a data-driven approach. Although our findings highlight the important role played by the cortex in higher order cognitive processes, future studies are needed to elucidate the individual contribution of individual and clinical attributes into the deficits observed in this population.

Efficient Defect-Driven Cation Exchange beyond the Nanoscale Semiconductors toward Antibacterial Functionalization.

Defect engineering is an exciting tool for customizing semiconductors' structural and optoelectronic properties. Elaborating programmable methodologies to circumvent energy constraints in multievent inversions expands our understanding of the mechanisms governing the functionalization of nanomaterials. Herein, we introduce a novel strategy based on defect incorporation and solution rationalization, which triggers energetically unfavorable cation exchange reactions in extended solids. Using Sb2X3 + Ag (I) → Ag: Sb2X3 (X= S, Se) as a system to model, we demonstrate that incorporating chalcogen vacancies and AgSbVX complex defects into initial thin films (TFs) is crucial for activating long-range solid-state ion diffusion. Additional regulation of the Lewis acidity of auxiliary chemicals provides an exceptional conversion yield of the Ag precursor into a solid-state product up to 90%, simultaneously transforming upper matrix layers into AgSbX2. The proposed strategy enables tailoring radiative recombination processes, offers efficiency to invert TFs at moderate temperatures quickly, and yields structures of large areas with substantial antibacterial activity in visible light for a particular inversion system. Similar customization can be applied to most sulfides/selenides with controlled reaction yields.

Organic changes of anal sphincter in complicated rectal fistulas

Aim. To evaluate the diagnostic significance of structural changes in the anal sphincter (AS) in patients with complex rectal fistulas (CRF).Materials and Methods. This study analyzed the results of examination and surgical treatment of 87 patients with rectal fistulas. Following a comprehensive assessment, the structural changes in the anal sphincter (SCAS) among patients with complex rectal fistulas were classified into several categories. The first subgroup included 16 patients (18.4%) with complex rectal fistulas accompanied by inflammatory infiltration of the anal sphincter (reactive sphincteritis, RS). The second subgroup consisted of 24 patients (27.6%) who exhibited fibrotic changes in the anal sphincter (anal sphincter pectenosis, ASP). The third subgroup comprised 17 patients (19.5%) with complex rectal fistulas and defects (diastasis of AS muscles) in the anal sphincter fibers. The fourth subgroup served as the comparison group, consisting of 30 patients (34.5%) with complex rectal fistulas but without organic changes in the AS.Results and Discussion. The primary complaint among all patients with complex rectal fistulas was the presence of a fistula opening with purulent discharge, although additional symptoms varied depending on the type of structural changes in the AS. The study demonstrated that ultrasound showed a sensitivity of 87%, specificity of 69%, and overall accuracy of 92% in diagnosing rectal fistulas, consistent with data reported by other researchers. On ultrasound, reactive sphincteritis presented as a homogeneous or heterogeneous structure of anal sphincter fibers with varying shapes and sizes, characterized by hyperechogenicity intimately adjacent to fluid accumulations (or intersphincteric localization), filled with contents of varying degrees of echogenicity depending on the stage of inflammation. The ultrasound characteristics of anal sphincter pectenosis (ASP) differed from RS, showing a decrease in sphincter fiber volume and deformation of the AS with retraction of the muscular ring. Defects in the internal sphincter were characterized by varying degrees of hypoechogenicity, with lengths ranging from 0.3 to 1.2 cm, and were more frequently observed along the posterior rectal wall.Conclusions. Complex rectal fistulas are often associated with organic changes in the structure of the anal sphincter, manifesting as reactive sphincteritis, anal sphincter pectenosis, and defects in the muscle fibers of the external anal sphincter. The clinical course of the disease in patients with ASP is influenced by both the type of rectal fistula and the nature and severity of SCAS.

Variability in patient-reported outcomes among different congenital heart defects: a comparative analysis of 7,498 patients from 32 countries

Abstract Background Patient-reported outcomes (PROs) may not always correlate with the complexity of congenital heart defects (CHDs), as significant variation has been observed between CHDs within complexity levels. Accurate comparisons across various types of CHDs necessitate large sample sizes. Purpose The objective of this study was to compare PROs across different CHDs in a large international sample. Methods ‘Assessment of Patterns of Patient-Reported Outcomes in Adults with Congenital Heart disease – International Study II’ (APPROACH-IS II) was an international cross-sectional investigation, in which 8,415 patients from 32 countries in 6 continents were enrolled (20 high; 7 upper-middle; 4 lower-middle; and 1 low income). For the comparison across different CHDs, conditions with at least 50 patients were included in the analysis. Hence, the sample consisted of 7,498 patients (median age=33y; 53.1% women). Patients completed questionnaires to measure perceived health status (RAND-12 Health Survey; EuroQOL-5D Visual Analog Scale); depressive symptoms (Patient Health Questionnaire-8); anxiety (General Anxiety Disorder-7) and quality of life (Linear Analog Scale). Generalized linear mixed models (GLMMs) were performed with center as random effect. Results Cyanotic heart defects were associated with the lowest scores for physical functioning, mental health, self-rated health, and quality of life (see Figure). Other CHDs found to be associated with poor PRO scores encompassed unrepaired secundum atrial septal defect, Ebstein anomaly, single ventricle, and truncus arteriosus. Conversely, the most favorable scores for all PROs, except for anxiety, were observed with isolated pulmonic stenosis. Other CHDs with favorable PRO scores comprised coarctation of the aorta, isolated small ventricular septal defect, congenital aortic valve disease, and repaired ventricular septal defect. Adjusted for sociodemographic and physiological factors, GLMMs revealed significant differences across defects, using the best score for each PRO as the reference (see Figure). Conclusion Substantial variation in PROs was observed among different types of CHDs. Interestingly, some complex heart defects demonstrated relatively good PRO scores, comparable to some simple defects. On the other hand, unrepaired simple defects or those with residual lesions, were associated with worse PROs.

Computationally Driven Discovery of T Center-like Quantum Defects in Silicon.

Quantum technologies would benefit from the development of high-performance quantum defects acting as single-photon emitters or spin-photon interfaces. Finding such a quantum defect in silicon is especially appealing in view of its favorable spin bath and high processability. While some color centers in silicon have been emerging in quantum applications, there remains a need to search for and develop new high-performance quantum emitters. By searching a high-throughput computational database of more than 22,000 charged complex defects in silicon, we identify a series of defects formed by a group III element combined with carbon ((A-C)Si with A = B, Al, Ga, In, Tl) and substituting on a silicon site. These defects are analogous structurally, electronically, and chemically to the well-known T center in silicon ((C-C-H)Si), and their optical properties are mainly driven by an unpaired electron on the carbon p orbital. They all emit in the telecom, and some of these color centers show improved properties compared to the T center in terms of computed radiative lifetime, emission efficiency, or smaller optical linewidth. The kinetic barrier computations and previous experimental evidence show that these T center-like defects can be formed through the capture of a diffusing carbon by a substitutional group III atom. We also show that the synthesis of hydrogenated T center-like defects followed by a dehydrogenation annealing step could facilitate the formation of these defects. Our work motivates further studies on the synthesis and control of this new family of quantum defects and demonstrates the use of high-throughput computational screening to discover new color center candidates.

Giant permittivity and humidity sensitivity of SrTiO3 based ceramics induced by K, Nb donor-acceptor co-doping

This research utilizes a solid-state sintering process to fabricate a series of Sr1-xKxTi1-xNbxO3 (x =0.01, 0.02, 0.025, 0.03) ceramics. The sample with a doping concentration of x=0.025 achieved a dielectric constant of 10409 and a dielectric loss of 0.026 at 1 kHz. With increased dopant concentrations of K and Nb, the thermal stability of the ceramics is significantly enhanced, as evidenced by a dielectric constant variation of less than 15 % for x=0.025 sample over a temperature range from room temperature to 240 °C. Employing activation energy analysis, impedance spectroscopy, humidity response assessments, and X-ray photoelectron spectroscopy, it is indicated that the excellent electrical performance is attributed to the combined effects of the Internal Barrier Layer Capacitance and the formation of complex defect dipoles. Moreover, the insights into the moisture characteristics of SrTiO3 presented in this paper imply that the giant dielectric Sr1-xKxTi1-xNbxO3 ceramics have potential in the application of humidity sensing devices.

Optical and electrical degradation behavior of GaN-based UV-A laser diodes

The degradation mechanism of GaN-based ultraviolet (UV-A) laser diodes (LDs) is analyzed by studying the changes of their electrical and optical properties after aging process with the operation current below the threshold current (Ith). After aging treatment, Ith increases, the slope efficiency decreases, and the leakage current increases. In particular, the emission spectra of aged LD show significant broadening, with additional peaks on the shorter wavelength side. Both cathodoluminescence and deep level transient spectrum results indicate defects can develop around the active region of the LD, even when the operation current is below Ith. This leads to an increase in trap-assisted tunneling current and non-radiative recombination. The observed defects may result from the diffusion of water molecule in the environment from the cavity facet into the active region and formation of ON–CN and VGaON complex defects. These defects not only reduce the effective carrier concentration injected into the quantum well but also increase non-radiative recombination. These results will contribute to our understanding of the degradation mechanism of UV LDs and the preparation of long lifetime UV LDs.

An Improved YOLOv9 and Its Applications for Detecting Flexible Circuit Boards Connectors

Flexible circuit boards are a cornerstone of the modern electronics industry. In automatic defect detection, FPC connectors present challenges such as minimal differences between oxidation defects and the background, easy degradation of Intersection over Union (IoU) scores, and significant variations in the shapes of black defect boundaries. Consequently, existing algorithms perform poorly in this task. We improve model YOLOv9 by introducing Multi-scale Dilated Attention (MSDA) on the output side to enhance the ability to capture features, and Deformable Large Kernel Attention (DLKA) on the other side of the output header to improve the ability to adapt to complex defect boundaries. Our use of IoU loss completely eliminates the risk of IoU degradation or gradient vanishing. Furthermore, we reduce computational overhead with the implementation of Faster Block. Following these improvements, the mean Average Precision (mAP) at 75% IoU (mAP75) for oxidized defects increased by 7.5% relative to the base model. Similarly, the mAP at 50% IoU (mAP50) for black defects increased by 5.7%, validating the relevance and efficacy of our proposed improvements. Overall, the average mAP50, mAP75, and mAP50:95 for all defects improved by 3.8%, 2.0%, and 2.3%, respectively. The performance gain achieved by our enhanced model significantly exceeds the improvement of YOLOv9 relative to YOLOv8.

Research on tire appearance defect detection algorithm based on efficient multi-scale convolution

Abstract Due to the large randomness of tire appearance defect size and the complex and diverse defect shapes, the existing target detection algorithm is prone to missing and misidentifying targets, the accuracy is limited, and the detection model is large, which is not conducive to deployment on embedded devices. In this paper, the efficient multi-scale convolution (EMC) mode is proposed, and the C2f-EMC module is designed on this basis, which improves the network structure of YOLOv8, improves the accuracy of tire appearance defect detection, and reduces the number of parameters in the model. EMC convolution first divides the input feature images into four parts on average and carries out multi-scale convolution with convolution cores of 1×1, 3×3, 5×5 and 7×7 sizes respectively. Then, the obtained results are stacked, and cross-channel feature fusion is realized by point-by-point convolution. After determining the network structure of C2f-EMC, the best improvement position of C2f-EMC module is determined through comparative experiments. Experiments show that after the above improvements, the parameter number of the model is reduced by 4.85%, the calculation amount by 2.82%, the model size by 4.44%, the recall rate by 2.8%, the mAP50 by 1.0%, the mAP50-95 by 1.3%, and the F1 by 2%. The defect detection task can be completed more accurately and the model size requirements of embedded devices can be better met.

A Radial Distribution Function Based Recognition Algorithm of Point Defects in Large-Scale β-Ga2O3 Systems.

The atomic configurations and concentrations of intrinsic defects profoundly influence the electrical and optical properties of the semiconductor materials. This influence is particularly significant in the case of β-Ga2O3, which is a highly promising ultrawide bandgap semiconductor characterized by highly complex intrinsic defect configurations. Despite its importance, there is a notable absence of an accurate method to recognize these defects in large-scale atomistic computational modeling. We design an effective algorithm for the explicit identification of various intrinsic point defects in the β-Ga2O3 lattice, which constitutes the integration of the particle swarm optimization (PSO) and K-means clustering (K-MC) methods. Our algorithm attains the recognition accuracy exceeding 95%. Finally, the algorithm is applied to dynamic simulations, where the feasibility of dynamic real-time detection is explored.

Microsurgical Reconstruction with and without Microvascular Anastomosis of Oncological Defects of the Upper Limb.

The choice of the most adequate surgical technique for upper limb defects remains challenging. The aim of this article is to discuss the main microsurgical (pedicled or free) reconstructive options for the post-oncological reconstruction of different anatomical areas of the upper extremity. We reviewed different reconstructive methods reported in the literature needing microsurgical expertise and compared them to our clinical experience, in order to provide further guidance in the choice of different flaps for upper limb soft tissue reconstruction. Six clinical cases, one for each anatomical district, are presented as examples of possible solutions. We report the options available in the literature for post-oncologic upper limb reconstruction, dividing them by anatomical area and type of flap: local flaps, regional flaps, free flaps, and distant pedicled flaps. Our examples of the reconstruction of each anatomical area of the upper limb include one reverse ulnar pedicled perforator flap, one free Antero-Lateral Thigh (ALT) flow-through flap, one perforator-based lateral arm flap, two myocutaneous latissimus dorsi pedicled flaps, and one parascapular perforator-plus flap. In oncological cases, it is important to consider reconstructive options that provide stable tissue and allow for the early healing of the donor and recipient site if the patient needs to undergo adjuvant radiotherapy or chemotherapy. A wider range of flap options is essential when choosing the proper technique according to the patient's needs, surgeon's preference, and logistical possibilities. Perforator flaps combine the advantages of other flaps, but they require microsurgical expertise. Free flap reconstruction remains the gold standard to obtain a better overall and cosmetic outcome in complex and wide defects, where no suitable local pedicled flap option exists. The pedicled latissimus dorsi flap should still be included among the reconstructive options for its strong vascularization, size, and arc of transposition.

Sensitive fluorescent biosensor reveals differential subcellular regulation of PKC.

The protein kinase C (PKC) family of serine and threonine kinases, consisting of three distinctly regulated subfamilies, has been established as critical for various cellular functions. However, how PKC enzymes are regulated at different subcellular locations, particularly at emerging signaling hubs, is unclear. Here we present a sensitive excitation ratiometric C kinase activity reporter (ExRai-CKAR2) that enables the detection of minute changes (equivalent to 0.2% of maximum stimulation) in subcellular PKC activity. Using ExRai-CKAR2 with an enhanced diacylglycerol (DAG) biosensor, we uncover that G-protein-coupled receptor stimulation triggers sustained PKC activity at the endoplasmic reticulum and lysosomes, differentially mediated by Ca2+-sensitive conventional PKC and DAG-sensitive novel PKC, respectively. The high sensitivity of ExRai-CKAR2, targeted to either the cytosol or partitioning defective complexes, further enabled us to detect previously inaccessible endogenous atypical PKC activity in three-dimensional organoids. Taken together, ExRai-CKAR2 is a powerful tool for interrogating PKC regulation in response to physiological stimuli.

Liquid chromatography-mass spectrometric method for the simultaneous analysis of branched-chain amino acids and their ketoacids from dried blood spot as secondary analytes for the detection of maple syrup urine disease

BackgroundMaple syrup urine disease (MSUD) is an aminoacidopathy caused by a defective branched-chain alpha-ketoacid dehydrogenase complex, leading to the accumulation of branched-chain amino acids (BCAAs) and their respective keto acids (BCKAs). A comprehensive test was developed to measure BCAAs and BCKAs using LC-MS from dried blood spot (DBS) samples for the diagnosis and prevention of MSUD in newborns and infants. MethodsAnalytes were extracted from DBS using a methanol:0.1 % v/v formic acid solution (75:25) containing internal standards and analyzed on a Luna PFP column (150 mm × 4.6 mm, 3 µm) at a flow rate of 0.3 mL/min. The method was validated for linearity, accuracy, precision, recovery, carry-over, matrix effect, hematocrit, blood volume, and punch position effects. Biomarker stability in the matrix and stock solution was assessed. Correlation with the plasma method was determined using Pearson’s correlation coefficient and Bland-Altman analysis. The method established reference ranges for the Udupi district population in South India. ResultsThe method demonstrated linearity (r2 > 0.99), with a lower limit of detection at 2 µM (BCAA) and 1 µM (BCKA), and acceptable recovery of QC samples. Hematocrit, blood volume, punch position, and storage condition effects were within acceptable limits. Correlation and Bland-Altman analysis showed strong interconvertibility between plasma and DBS assays. Reference ranges for leucine, isoleucine, valine, KIC, KIV, and KMV were established. ConclusionThe developed DBS method, requiring no derivatization and involving simple sample preparation with short run times, is a cost-effective and reliable approach for the confirmatory diagnosis of MSUD.

AIDM-CT: software for cone-beam X-ray tomography and deep-learning-based analysis

ABSTRACT Non-destructive testing (NDT) with high-resolution cone-beam X-ray computed tomography (XCT) plays a crucial role in revealing the 3D distribution and morphology of defects within an object. It’s necessary to generalise an intelligent and customised XCT-based NDT protocol, providing solutions for reconstruction quality improvement and complex defect quantitative analysis for users. We analysed the key techniques of XCT and developed the systematic software for data acquisition, reconstruction, intelligent super-resolution and segmentation in our advanced imaging and data mining laboratory (AIDM-CT). The experimental results demonstrated the software efficiently achieves the control of XCT scanning, artefact correction algorithms related to cone-beam geometrics, beam hardening, ring and radial artefacts, deep-learning based slice super-resolution and feature segmentation, and quantitative analysis. The software is programmed by Python language to provide the friendly multi-function graphical user interface (GUI), in which the programming of reconstruction and corrections combined with Computer Unified Device Architecture (CUDA) acceleration to guarantee the high efficiency of XCT task. Particularly, the multi-functional super resolution module (MF-GAN) is proposed to optimise the quality of CT image and the improved U-Net segmentation module (CBAM U-Net) is also developed to fulfill the high-precision quantitative non-destructive testing of homogeneous and variform microdefects in our AIDM-CT software.

Mechanisms of enhanced performance in Zr4+/Ta5+ codoped rutile-TiO2 ceramics via broadband dielectric spectroscopy.

Aliovalent dopant codoped rutile-TiO2 materials have garnered attention due to their excellent performance properties, characterized by low loss tangent (tanδ), high dielectric permittivity (ε'), and stable ε' over a broad temperature range. This performance is primarily due to the electron-pinned defect-dipoles (EPDDs) of the complex defects [Formula: see text]Ti3+-[Formula: see text]Ti3+BTi. Notably, the excellent dielectric properties in ZrxTa2.5%Ti0.975-xO2 (Zr-TTO) ceramics can be achieved using the traditional mixed oxide method without the EPDDs, due to the absence of A3+ (acceptor doping ions). Instead, the existence of localized free electrons and oxygen vacancies ([Formula: see text]) in Zr-TTO structures, due to doping ions and the sintering process, was confirmed by X-ray photoelectron and Raman spectroscopies. These ceramics exhibited ε'~ 2 × 104 and tanδ < 0.03 at 1kHz and 25°C in the 2.5-10%Zr-TTO samples. Moreover, all ceramics demonstrated a maximum ε' change (∆ε') of less than ±15% over the temperature range suitable for X7R and X8R type ceramic capacitors. Significantly, the change in ε' related to relative humility was calculated to be less than ±0.5% over the range of 50-95% RH, indicating the environmental stability of the dielectric properties, which is essential for capacitor applications. Investigations suggested that at least four mechanisms contributed to this system: the intrinsic effect of ionic polarization, Ti4+ · e- -[Formula: see text]- Ti4+ · e- and Ti4+ · e- - [Formula: see text] defects, interfacial polarization at insulating grain boundaries, and non-Ohmic contact between the surface sample and the metal electrode.

MIR164B ensures robust Arabidopsis leaf development by compensating for compromised POLYCOMB REPRESSIVE COMPLEX2 function.

Robustness is pervasive throughout biological systems, enabling them to maintain persistent outputs despite perturbations in their components. Here, we reveal a mechanism contributing to leaf morphology robustness in the face of genetic perturbations. In Arabidopsis (Arabidopsis thaliana), leaf shape is established during early development through the quantitative action of the CUP-SHAPED COTYLEDON2 (CUC2) protein, whose encoding gene is negatively regulated by the co-expressed MICRORNA164A (MIR164A) gene. Compromised epigenetic regulation due to defective Polycomb Repressive Complex 2 (PRC2) function results in the transcriptional derepression of CUC2 but has no impact on CUC2 protein dynamics or early morphogenesis. We solve this apparent paradox by showing that compromised PRC2 function simultaneously derepresses the expression of another member of the MIR164 gene family, MIR164B. This mechanism dampens CUC2 protein levels, thereby compensating for compromised PRC2 function and canalizing early leaf morphogenesis. Furthermore, we show that this compensation mechanism is active under different environmental conditions. Our findings shed light on how the interplay between different steps of gene expression regulation can contribute to developmental robustness.

Shape Memory Polymer Bioglass Composite Scaffolds Designed to Heal Complex Bone Defects.

An off-the-shelf scaffold with requisite properties could enable the viable treatment of irregular craniomaxillofacial bone defects. Notably, the scaffold should be conformally fitting, innately bioactive, and bioresorbable. In prior work, we developed a series of shape memory polymer (SMP) scaffolds based on cross-linked poly(ε-caprolactone) (PCL). These were capable of "self-fitting" into complex bone defects when exposed to temperatures above the melt transition of the constituent PCL, either linear-PCL-diacrylate (linear-PCL-DA, Tm ∼55 °C) or star-PCL-tetraacrylate (star-PCL-TA, Tm ∼45 °C) for the potential to improve tissue safety. To achieve favorably increased degradation rates versus PCL-only scaffolds, semi-interpenetrating networks (semi-IPNs) were formed by including linear- or star-poly(l-lactic acid) (PLLA). A potential limitation of these self-fitting scaffolds is the lack of bioactivity, which is essential to osteoinductivity and osseointegration. Herein, analogous composite scaffolds were formed with 45S5 bioglass (BG) to impart bioactivity. The solvent-cast particulate leaching fabrication method was adapted to introduce BG to the fused salt template, resulting in composites with BG concentrated on the pore wall surfaces rather than within pore struts. Composite scaffolds with good pore wall integrity were produced with 2.5, 5, and 10 wt % BG. All composite scaffolds exhibited non-brittle behavior and did not fracture with 85% strain. For semi-IPN composite scaffolds, PLLA crystallinity was lost, and mechanical properties were not appreciably altered versus the non-BG controls. Sufficient retention of PCL crystallinity led to excellent shape memory behavior. The inclusion of 5 and 10 wt % BG led to hydroxyapatite mineralization after 1 day of exposure to simulated body fluid, as well as increased rates of in vitro degradation.

Integrating Clay Modeling in Implant Fabrication for Craniofacial Defect.

Manufacturing craniofacial implants using 3-dimensional (3D) methods and computed tomography data has become popular. The image object for the defect is produced as the first step, followed by several methods to create the implant. The authors have used a novel method that combines clay modeling with 3D scanning to create implants for craniofacial contour reconstruction. This approach does not require complicated resources. The method allows for high customization and immediate modifications, resulting in implants that achieve an accurate fit and high patient satisfaction. It is particularly beneficial for addressing complex defects and achieving aesthetic improvements. In addition, it reduces the need for cumbersome digital processing and expensive materials, making it a practical and feasible solution for a wide range of craniofacial deformities.

Internal damage evolution of C/SiC composites in air at 1650 °C studied by in-situ synchrotron X-ray imaging

Carbon fibre reinforced silicon carbide (C/SiC) ceramic matrix composites have attracted considerable attention due to their exceptional properties and extensive potential applications as high-temperature structural materials. However, due to their complex structure and manufacturing defects, C/SiC composites exhibit intricate mechanical behaviour under thermal-mechanical-oxidative coupling environments. To date, systematic studies on the internal damage evolution and failure mechanisms of C/SiC composites under high-temperature oxidative environments are lacking. In this study, a combination of synchrotron X-ray micro-computed tomography (SR-μCT) and in-situ experiments under thermal-mechanical-oxidative coupling environments at room temperature and 1650 °C in air was used to characterize the internal microstructures and damage evolution processes of C/SiC composites at different loading levels. Additionally, the 3D strain fields during in-situ loading were quantitatively analysed using the Digital Volume Correlation (DVC) method. The findings underscore the substantial impact of oxidative damage on the mechanical response of C/SiC composites, particularly concerning tensile properties and fracture modes. At room temperature, severe delamination, fibre bundle pull-out and interfacial debonding occurred internally. Whereas, under high-temperature atmospheric conditions, severe fibre oxidation reactions occurred at the specimen edges, resulting in rapid porosity escalation. Crack initiation from surface defects followed by rapid inward propagation is observed. Moreover, while the strain distribution remains relatively uniform until fracture, a pronounced concentration of strain is evident near the fracture zones at room temperature, with an even greater concentration observed at 1650 °C. Notably, the region of concentrated strain within the 3D deformation field corresponds closely to the final fracture location, as revealed by quantitative DVC analysis.