Investigation of Fatigue Crack Initiation and Growth in Cast MAR-M247 Subjected to Low Cycle Fatigue at Room Temperature

MC carbide particles (with Hafnium and/or Tantalum as constituent metallic element, M) were observed to crack extensively in a cast polycrystalline nickel-base superalloy, MAR-M247, when subjected to low-cycle fatigue loading at room temperature. High resolution secondary electron images taken on the surface of a double edge notch test specimen revealed that approximately half the carbide particles cracked in the highly-strained notch section of the specimen. These images further illustrated that the average surface area of cracked particles was approximately three times that of the uncracked particles. Additional analysis illustrated that the cracks within a large number of particles aligned nearly perpendicular to the loading direction. However, high aspect ratio particles (with aspect ratio >3) were prone to incubate cracks aligned along its major axis, independent of the loading direction. Additionally, forward-scattered imaging often showed a high density of slip bands interaction with most of the particles which cracked. The life limiting crack growth in MAR-M247 was observed to be crystallographic in nature, as the crack grew along slip bands as measured by high-resolution electron backscatter diffraction, even after spanning many grains. Statistically representative microstructure models of MAR-M247 were generated and used in the crystal plasticity finite element simulations. As expected, there was a significant variation in the computed stress state among constituent carbide particles. The stress state of the carbide particles was found to be heavily influenced by the stress in surrounding grains and the orientation of the major axis of the particles with respect to applied load direction. For particles that intersect the free-surface, stress was found to be highly concentrated at the free surface and a positive correlation between the magnitude of free-surface area and the maximum principal stress was found. Additionally, high stress concentrations were observed in regions where carbide particles intersect grain boundaries

GaAs on Si epitaxy by aspect ratio trapping: analysis and reduction of defects propagating along the trench direction

The Aspect Ratio Trapping technique has been extensively evaluated for improving the quality of III-V heteroepitaxial films grown on Si, due to the potential for terminating defects at the sidewalls of SiO2 patterned trenches that enclose the growth region. However, defects propagating along the trench direction cannot be effectively confined with this technique. We studied the effect of the trench bottom geometry on the density of defects of GaAs fins, grown by metal-organic chemical vapor deposition on 300 mm Si (001) wafers inside narrow (<90 nm wide) trenches. Plan view and cross sectional Scanning Electron Microscopy and Transmission Electron Microscopy, together with High Resolution X-Ray Diffraction, were used to evaluate the crystal quality of GaAs. The prevalent defects that reach the top surface of GaAs fins are {111} twin planes propagating along the trench direction. The lowest density of twin planes, 8 108 cm 2, was achieved on “V” shaped bottom trenches, where GaAs nucleation occurs only on {111} Si planes, minimizing the interfacial energy and preventing the formation of antiphase boundaries

Characterization of Titanium Alloys Produced by Electron Beam Directed Energy Deposition

Functionally graded materials offer the potential to improve structural efficiency by allowing the material composition and/or microstructural features to spatially vary within a component. Additive manufacturing techniques enable the fabrication of such graded materials and structures. While examining several titanium alloys, this paper focuses on Ti-8Al-1Er as it has a unique microstructure that is only feasible when produced by rapid solidification methods like electron beam directed energy deposition, an additive manufacturing process. The results show that, when mixed, Ti-8Al-1Er and commercially-pure titanium uniformly mix at various ratios and the resultant static tensile properties of the mixed alloys behave according to rule-of-mixtures. At discontinuous interfaces between Ti-8Al-1Er and commercially-pure titanium, the crack growth behavior progresses smoothly across the discontinuity as the crack transitions from one crack growth regime into another. Studies on monolithic samples shows the mechanisms of damage in the Ti-8Al-1Er; specifically, that strain localization occurs near grain boundaries of high mis-orientation on the microscale and that twinning and dislocation density is concentrated near erbia-strengthening particles (Er2O3) on the nanoscale

Pseudo Trained YOLO R_CNN Model for Weapon Detection with a Real-Time Kaggle Dataset

The Recurrent Convolutional Neural Networks (RCNN) based deep learning models has been classified image patterns and deep features through layer architecture. In this world every country doesn’t encouraging violence, so that indirectly nations prohibiting usages of weapons to common people. This study proposes a novel YoLo Faster R-CNN based weapon detection algorithm for unusual weapon object detection. The proposed YoLo V3 R-CNN computer vision application can rapidly find weapons carried by people and highlighted through bounding-box-intimation. The work plan of this research is divided into two stages, at 1st stage pre-processing has been called to Faster R-CNN segmentation. The 2nd stage has been training the dataset as well as extracting 8-features (image_id, detection score, pixels-intensity, resolution, Aspect-ratio, PSNR, CC, SSIM) into .csv file. The labeling can be performed to RCNN-YoLo method such that getting real-time objects detection (Unusual things). The Confusion matrix has been generating performance measures in terms of accuracy 97.12%, SSIM 0.99, sensitivity 97.23%, and throughput 94.23% had been attained which are outperformance methodology

Pseudo Trained YOLO R_CNN Model for Weapon Detection with a Real-Time Kaggle Dataset

The Recurrent Convolutional Neural Networks (RCNN) based deep learning models has been classified image patterns and deep features through layer architecture. In this world every country doesn’t encouraging violence, so that indirectly nations prohibiting usages of weapons to common people. This study proposes a novel YoLo Faster R-CNN based weapon detection algorithm for unusual weapon object detection. The proposed YoLo V3 R-CNN computer vision application can rapidly find weapons carried by people and highlighted through bounding-box-intimation. The work plan of this research is divided into two stages, at 1st stage pre-processing has been called to Faster R-CNN segmentation. The 2nd stage has been training the dataset as well as extracting 8-features (image_id, detection score, pixels-intensity, resolution, Aspect-ratio, PSNR, CC, SSIM) into .csv file. The labeling can be performed to RCNN-YoLo method such that getting real-time objects detection (Unusual things). The Confusion matrix has been generating performance measures in terms of accuracy 97.12%, SSIM 0.99, sensitivity 97.23%, and throughput 94.23% had been attained which are outperformance methodology

Essential versus accessory aspects of cell death: recommendations of the NCCD 2015

Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as ‘accidental cell death’ (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. ‘Regulated cell death’ (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death

Mechanistic framework to link root growth models with weather and soil physical properties, including example applications to soybean growth in Brazil

Background and aimsRoot elongation is generally limited by a combination of mechanical impedance and water stress in most arable soils. However, dynamic changes of soil penetration resistance with soil water content are rarely included in models for predicting root growth. Better modelling frameworks are needed to understand root growth interactions between plant genotype, soil management, and climate. Aim of paper is to describe a new model of root elongation in relation to soil physical characteristics like penetration resistance, matric potential, and hypoxia.MethodsA new diagrammatic framework is proposed to illustrate the interaction between root elongation, soil management, and climatic conditions. The new model was written in Matlab®, using the root architecture model RootBox and a model that solves the 1D Richards equations for water flux in soil. Inputs: root architectural parameters for Soybean; soil hydraulic properties; root water uptake function in relation to matric flux potential; root elongation rate as a function of soil physical characteristics. Simulation scenarios: (a) compact soil layer at 16 to 20 cm; (b) test against a field experiment in Brazil during contrasting drought and normal rainfall seasons.Results(a) Soil compaction substantially slowed root growth into and below the compact layer. (b) Simulated root length density was very similar to field measurements, which was influenced greatly by drought. The main factor slowing root elongation in the simulations was evaluated using a stress reduction function.ConclusionThe proposed framework offers a way to explore the interaction between soil physical properties, weather and root growth. It may be applied to most root elongation models, and offers the potential to evaluate likely factors limiting root growth in different soils and tillage regimes

Angiotensin II stimulates superoxide production by nitric oxide synthase in thick ascending limbs

Angiotensin II (Ang II) causes nitric oxide synthase (NOS) to become a source of superoxide (O2 (-)) via a protein kinase C (PKC)-dependent process in endothelial cells. Ang II stimulates both NO and O2 (-) production in thick ascending limbs. We hypothesized that Ang II causes O2 (-) production by NOS in thick ascending limbs via a PKC-dependent mechanism. NO production was measured in isolated rat thick ascending limbs using DAF-FM, whereas O2 (-) was measured in thick ascending limb suspensions using the lucigenin assay. Consistent stimulation of NO was observed with 1 nmol/L Ang II (P \u3c 0.001; n = 9). This concentration of Ang II-stimulated O2 (-) production by 50% (1.77 ± 0.26 vs. 2.62 ± 0.36 relative lights units (RLU)/s/μg protein; P \u3c 0.04; n = 5). In the presence of the NOS inhibitor L-NAME, Ang II-stimulated O2 (-) decreased from 2.02 ± 0.29 to 1.10 ± 0.11 RLU/s/μg protein (P \u3c 0.01; n = 8). L-arginine alone did not change Ang II-stimulated O2 (-) (2.34 ± 0.22 vs. 2.29 ± 0.29 RLU/s/μg protein; n = 5). In the presence of Ang II plus the PKC α/β1 inhibitor Gö 6976, L-NAME had no effect on O2 (-) production (0.78 ± 0.23 vs. 0.62 ± 0.11 RLU/s/μg protein; n = 7). In the presence of Ang II plus apocynin, a NADPH oxidase inhibitor, L-NAME did not change O2 (-) (0.59 ± 0.04 vs. 0.61 ± ×0.08 RLU/s/μg protein; n = 5). We conclude that: (1) Ang II causes NOS to produce O2 (-) in thick ascending limbs via a PKC- and NADPH oxidase-dependent process; and (2) the effect of Ang II is not due to limited substrate

Interplay between IL-10, IFN-γ, IL-17A and PD-1 Expressing EBNA1-Specific CD4+ and CD8+ T Cell Responses in the Etiologic Pathway to Endemic Burkitt Lymphoma

Children diagnosed with endemic Burkitt lymphoma (eBL) are deficient in interferon-γ (IFN-γ) responses to Epstein–Barr Nuclear Antigen1 (EBNA1), the viral protein that defines the latency I pattern in this B cell tumor. However, the contributions of immune-regulatory cytokines and phenotypes of the EBNA1-specific T cells have not been characterized for eBL. Using a bespoke flow cytometry assay we measured intracellular IFN-γ, IL-10, IL-17A expression and phenotyped CD4+ and CD8+ T cell effector memory subsets specific to EBNA1 for eBL patients compared to two groups of healthy children with divergent malaria exposures. In response to EBNA1 and a malaria antigen (PfSEA-1A), the three study groups exhibited strikingly different cytokine expression and T cell memory profiles. EBNA1-specific IFN-γ-producing CD4+ T cell response rates were lowest in eBL (40%) compared to children with high malaria (84%) and low malaria (66%) exposures (p < 0.0001 and p = 0.0004, respectively). However, eBL patients did not differ in CD8+ T cell response rates or the magnitude of IFN-γ expression. In contrast, eBL children were more likely to have EBNA1-specific CD4+ T cells expressing IL-10, and less likely to have polyfunctional IFN-γ+IL-10+ CD4+ T cells (p = 0.02). They were also more likely to have IFN-γ+IL-17A+, IFN-γ+ and IL-17A+ CD8+ T cell subsets compared to healthy children. Cytokine-producing T cell subsets were predominantly CD45RA+CCR7+ TNAIVE-LIKE cells, yet PD-1, a marker of persistent activation/exhaustion, was more highly expressed by the central memory (TCM) and effector memory (TEM) T cell subsets. In summary, our study suggests that IL-10 mediated immune regulation and depletion of IFN-γ+ EBNA1-specific CD4+ T cells are complementary mechanisms that contribute to impaired T cell cytotoxicity in eBL pathogenesis