Search results for "Crack"

Connexin 43, Bcl-2, Bax, Ki67, and E-cadherin patterns in oral squamous cell carcinoma and its relationship with GJA1 rs12197797 C/G

2022

To our knowledge, there is no useful and accurate prognostic biomarker or biomarkers for patients with oral squamous cell carcinoma (OSCC), a tumor with uncertain biological behavior, and unpredicTable clinical progress. The purposes of this study were: a) to determine the expresión profile of Connexin 43, Bcl-2, Bax, E-cadherin, and Ki67 in patients with OSCC; b) identify the GJCA1 rs12197797 genotypic composition. A cross-sectional study using genomic DNA and biopsy samples extracted from the oral mucosa with/without OSCC, older than 18 years, both genders, attended at Facultad de Odontología, Universidad Nacional Córdoba. Immunostaining for Cx43, Bcl-2, Bax, E-cadherin, and Ki67 and geno…

Nutcracker syndrome due to left renal vein compression by an aberrant right renal artery

2007

Classic nutcracker syndrome is caused by left renal vein compression between the superior mesenteric artery and aorta, leading to retrograde venous hypertension associated with such urinary abnormalities as hematuria or proteinuria. We describe a case of symptomatic nutcracker syndrome treated by means of stent placement in which hypertension in the left renal vein was caused by stenosis of this vein compressed by an aberrant right renal artery at a point closer to the inferior vena cava.

Theta-1 zeolite catalyst for increasing the yield of propene when cracking olefins and its potential integration with an olefin metathesis unit

2017

[EN] There is a need for on-purpose propene production technologies beyond energy-intensive steam cracking. Hexene is a compound with limited value that can be found in several streams in the refinery and can readily crack on zeolites at lower temperatures and shorter contact times than those used for cracking alkanes. Cracking over ZSM-5 zeolite yields high selectivity to light olefins. These results are improved by Theta-1 zeolite, which can yield a remarkable propene molar selectivity of 180% (90 wt%) at 90% conversion, close to the maximum thermodynamic yield. Moreover, crystal engineering allowed its TOF to increase by more than 50%. Based on these results we also identified some prosp…

Elucidating the Effect of Bimodal Grain Size Distribution on Plasticity and Fracture Behavior of Polycrystalline Materials

2020

The refinement of grains in a polycrystalline material leads to an increase in strength but as a counterpart to a decrease in elongation to fracture. Different routes are proposed in the literature to try to overpass this strength-ductility dilemma, based on the combination of grains with highly contrasted sizes. In the simplest concept, coarse grains are used to provide relaxation locations for the highly stressed fine grains. In this work, a model bimodal polycrystalline system with a single coarse grain embedded in a matrix of fine grains is considered. Numerical full-field micro-mechanical analyses are performed to characterize the impact of this coarse grain on the stress-strain const…

2019

Abstract The fatigue life of thermally sprayed Al2O3- and Cr2O3-based coatings has been studied under low-energy (0.7–5 mJ) impact conditions. A threshold impact energy and amount of repetitions the coatings can endure with said energy before catastrophic failure was obtained. The catastrophic failure was determined to occur when the fracture mode of the coating switched from brittle cone cracking to quasi-plastic radial cracking. The results are examined relative to the microstructural features along with other properties of the coatings - hardness and cavitation resistance. The experiment provided a new approach for a straightforward comparison of the micro-scale impact fatigue life of th…

The effects of laboratory ageing on rheological and fracture characteristics of different rubberised bitumens

2018

Ageing of bituminous materials can result in loss of the durability of a flexible pavement. Using rubberised bitumens can enhance pavement performance while at the same time it solves a serious waste disposal problem. Combining Warm Mix Asphalt (WMA) additives with rubberised bitumens reduces the difficulties associated with the production of asphalt mixtures using this modified binder. This work was conducted to study the effect of ageing using fundamental parameters based on performance, i.e., CTOD and Glover-Rowe parameters have been related to pavement cracking. Different unmodified bitumens and rubberised bitumens were short-term aged using the Thin Film Oven Test (TFOT) and long- term…

A simple model for the calculation of the axial load-carrying capacity of corroded RC columns

2015

In the present paper, a simplified model is used to determine the axial load-carrying capacity of compressed short reinforced concrete columns subjected to corrosion processes. The model considers members with circular and square cross-sections and accounts for—cover spalling, —concrete core confinement induced by transverse steel reinforcement, —buckling of longitudinal reinforcing bars. Strength reduction in concrete cover and core due to cracking induced by rust formation, reduction of steel area in longitudinal bars and transverse stirrups due to general and pitting corrosion and loss of confinement pressure are considered. The load-carrying capacity and load-axial strain curves here ge…

Thermo-rheological analysis of WMA-additive modified binders

2020

AbstractThermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R…

Fracture toughness of synthesised high-performance epoxies subject to accelerated water aging

2018

Abstract The effects of water uptake on the fracture toughness of epoxy systems with high glass-transition temperatures (Tg above 170 °C) are investigated. Aging conditioning has been conducted in hot water, followed by a desorption conditioning in a room temperature dry-airborne. Water aging determines plasticisation effects and crosslink-density modifications, revealed by reductions of the Tg. It is less known how such modifications influence the material fracture toughness. In this study, Single Edge Notched Bending samples have been tested according to standards, to evaluate the KIC fracture toughness at different stages of water absorption-desorption. The characterisation has been supp…

Laser ultrasonics for defect evaluation on coated railway axles

2020

Abstract This scientific paper focuses on the application of an advanced non-destructive technique for an effective inspection of railway axles. The method pertains to ultrasonic techniques, which are widely used in the railway field. The experimental investigation was carried out on simulated defects tooled near the cross section reduction of the axle, in order to simulate fatigue cracks which, due to notch effect, can trigger crack propagation and axle failure. The aim of this research activity is to evaluate how efficiently the proposed technique detects defects and to verify its applicability to axles with a black coating for protection. In view of the experimental setup, comprising a p…