The Effect of Geometric Configurations on the Elastic Behavior of an Edge-Cracked Bonded Strip

Interface cracks often initiate around the bonding free-edge corner due to the high-stress concentration. In this research, the elastic behavior of an edge-cracked dissimilar bonded strip subjected to remote tensile load is investigated using the proportional crack tip opening displacement method based on FE analysis for arbitrary material combinations. The stress intensity factor, energy release rate, and mode mixity are computed and compared systematically with varying geometrical configurations and material combinations. Then, the combined effects of the relative height of the bonded component and material combination are discussed for the typical engineering materials

Stress intensity factor solutions for several crack problems using the proportional crack opening displacements

A general finite element procedure based on the proportional crack opening displacements for obtaining the stress intensity factors is presented. The procedure is applied to the nonsingular 3-node linear, 4-node linear, 8-node parabolic, 8-node axisymmetric elements and 8-node hexahedral solid elements for a test. It is found that the current method exhibits good element type adaptability and significantly less mesh dependency, and accurate results can be obtained effectively using rather coarse meshes. The accuracy of the current procedure is evaluated by applying it to two-dimensional interface cracks, three-dimensional penny-shaped cracks as well as circumferential surface cracks. Comparison with the published data from the literature shows that the current procedure gives accurate stress intensity factors. Furthermore, the current method is fairly efficient and less computational resource consuming and can be used as an effective tool in the reliability analysis of the bonded multi-layers

Electromagnetic interaction of arbitrary radial-dependent anisotropic spheres and improved invisibility for nonlinear-transformation-based cloaks

An analytical method of electromagnetic wave interactions with a general radially anisotropic cloak is established. It is able to deal with arbitrary parameters ($\epsilon_r(r)$, $\mu_r(r)$, $\epsilon_t(r)$ and $\mu_t(r)$) of a radially anisotropic inhomogeneous shell. The general cloaking condition is proposed from the wave relations for the first time. We derive the parameters of a novel class of spherical nonlinear cloaks and examine its invisibility performance by the proposed method at various nonlinear situations. Spherical metamaterial cloaks with improved invisibility performance is achieved with optimal nonlinearity in transformation and core-shell ratio.Comment: 19 pages, 9 figure

Activating KRAS Mutations in Arteriovenous Malformations of the Brain: Frequency and Clinicopathologic Correlation

Arteriovenous malformations (AVM) of the brain are considered congenital. Most AVMs are presumably sporadic, however rare familial cases occur and they may be observed in certain genetic disorders. We sought to determine the frequency of KRAS mutations and their association with clinicopathologic characteristics. We searched our neuropathology database from 2014–2017 for resected AVMs of the brain or dura mater. Twenty-one AVMs were tested (12 females, 9 males; average age: 32 years). KRAS mutations were found in 6/21 cases (28.5%). Five mutations were p.G12 V, and one p.G12C. The KRAS-mutant group contained 4 females and 2 males, with an average age of 28 years, compared to 34 years in the non-mutant group (P = .54). The average AVM size in the KRAS-mutant group was 3.9 cm, compared to 3.1 cm in the non-mutant group (P = .52). There were no histologic differences between KRAS-mutant and non-mutant cases. In summary, KRAS mutations occur in almost one third of brain AVMs. KRAS p.G12 V was the most common mutation identified. We also demonstrate the first reported instance of a KRAS p.G12C mutation in a brain AVM. The mean age of patients with KRAS-mutant AVMs was lower than the non-mutant group, and the mean size larger. Histologic characteristics were equally distributed between KRAS-mutant and non-mutant groups

Inherited Forms of Bladder Cancer: A review of Lynch Syndrome and Other Inherited Conditions

Environmental factors that play a role in the urothelial carcinogenesis have been well characterized. Current research is continuously exploring potential heritable forms of bladder cancer. Lynch syndrome is a well-known inheritable disease that increases the risk for a variety of cancers, including urothelial carcinomas. Screening of patients with known Lynch syndrome is important to evaluate for development of new primary tumors. Further study may provide more information on what level of follow-up each patient needs. Recent data suggest that mismatch repair mutations confer a greater risk for urothelial cancer. Additional large patient series as well as advancement of molecular testing may provide triage for Lynch syndrome patients in regards to the frequency and type of screening best suited for individual patient

Müllerian Adenosarcoma of the Urinary Bladder: Clinicopathologic and Immunohistochemical Features with Novel Genetic Aberrations

Müllerian adenosarcoma is a biphasic neoplasm most commonly of the uterus and less frequently of the ovary. It has been rarely described to occur in other sites such as peritoneum and liver. In this study, we report the clinicopathologic, immunohistochemical and molecular features of a primary müllerian adenosarcoma of the urinary bladder in a 62-year-old woman. To our knowledge, this is the first report of müllerian adenosarcoma primary to the urinary bladder in the literature. Light microscopy showed a biphasic epithelial and stromal tumor with benign-appearing glands surrounded by endometrial-type stroma that is densely cellular with increased mitotic figures. The stroma surrounding the glands is more cellular than the intervening areas, which are more loose and edematous. Immunohistochemistry profile included positive staining for Pax2/8 within the glands, for CD10 and WT-1 within the spindled stroma, and for estrogen and progesterone receptors in both. Staining for desmin, GATA3, p63, and human papilloma virus (HPV) is negative. Molecular analyses identified mutations in AKT1 E17K, FLT3 D835N, KRAS G12D and HRAS G12S. These novel molecular aberrations have yet to be reported in the medical literature. X chromosome inactivation analysis revealed a clonal pattern in the stromal component and a non-clonal pattern in the epithelial component. Currently, the patient is disease/recurrence-free after regular follow-up of approximately 84 months. This case represents the first reported diagnosis of müllerian adenosarcoma arising in the urinary bladder with extensive clinicopathologic, immunohistochemical, and molecular analyses

FGFR3 and TP53 mutation analysis in inverted urothelial papilloma: incidence and etiological considerations

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Next-Generation Sequencing to Detect Deletion of RB1 and ERBB4 Genes in Chromophobe Renal Cell Carcinoma: A Potential Role in Distinguishing Chromophobe Renal Cell Carcinoma from Renal Oncocytoma

Overlapping morphologic, immunohistochemical, and ultrastructural features make it difficult to diagnose chromophobe renal cell carcinoma (ChRCC) and renal oncocytoma (RO). Because ChRCC is a malignant tumor, whereas RO is a tumor with benign behavior, it is important to distinguish these two entities. We aimed to identify genetic markers that distinguish ChRCC from RO by using next-generation sequencing (NGS). NGS for hotspot mutations or gene copy number changes was performed on 12 renal neoplasms, including seven ChRCC and five RO cases. Matched normal tissues from the same patients were used to exclude germline variants. Rare hotspot mutations were found in cancer-critical genes (TP53 and PIK3CA) in ChRCC but not RO. The NGS gene copy number analysis revealed multiple abnormalities. The two most common deletions were tumor-suppressor genes RB1 and ERBB4 in ChRCC but not RO. Fluorescence in situ hybridization was performed on 65 cases (ChRCC, n = 33; RO, n = 32) to verify hemizygous deletion of RB1 (17/33, 52%) or ERBB4 (11/33, 33%) in ChRCC, but not in RO (0/32, 0%). In total, ChRCCs (23/33, 70%) carry either a hemizygous deletion of RB1 or ERBB4. The combined use of RB1 and ERBB4 fluorescence in situ hybridization to detect deletion of these genes may offer a highly sensitive and specific assay to distinguish ChRCC from RO

Unusual Electrical Conductivity Driven by Localized Stoichiometry Modification at Vertical Epitaxial Interfaces

Precise control of lattice mismatch accommodation and cation interdiffusion across the interface is critical to modulate correlated functionalities in epitaxial heterostructures, particularly when the interface composition is positioned near a compositional phase transition boundary. Here we select La1-xSrxMnO3 (LSMO) as a prototypical phase transition material and establish vertical epitaxial interfaces with NiO to explore the strong interplay between strain accommodation, stoichiometry modification, and localized electron transport across the interface. It is found that localized stoichiometry modification overcomes the plaguing dead layer problem in LSMO and leads to strongly directional conductivity, as manifested by more than three orders of magnitude difference between out-of-plane to in-plane conductivity. Comprehensive structural characterization and transport measurements reveal that this emerging behavior is related to a compositional change produced by directional cation diffusion that pushes the LSMO phase transition from insulating into metallic within an ultrathin interface region. This study explores the nature of unusual electric conductivity at vertical epitaxial interfaces and establishes an effective route for engineering nanoscale electron transport for oxide electronics