On the Effects of Residual Stresses Induced by Coated and Uncoated Cutting Tools with Finite Edge Radii in Turning Operations

This paper presents an analysis of residual stresses in turning of AISI 316L and AISI 1045 steels with coated and uncoated tools having finite edge radii. An analytical predictive model, and experimental techniques involving X-ray diffraction and IR thermal imaging were used. Machining with coated tools produce higher superficial residual stresses, larger tensile layer thickness and higher residual stresses below the machined surface when using large cutting edge radii at low feed rates. This effect is correlated with the increase in the amount of heat conducted into the workpiece, and the associated generation of high tensile residual stresses and severe work-hardening.http://www.sciencedirect.com/science/article/B8CXH-4P37B21-X/1/ade5f4d85d7cb77cb37cbb62ae400bb

Smuggled. Film Screening

https://scholarworks.sjsu.edu/chc_flyers/1031/thumbnail.jp

Thermo-mechanical effects in drilling using metal working fluids and cryogenic cooling and their impact in tool performance

Cryogenic machining opens up new industrial perspectives in difficult-to-cut materials like nickel-based alloys. In particular, drilling is an operation that generates high thermal and mechanical loading to the drill. There- fore, tool performance, hole geometry and surface integrity can be highly affected. The objective of this study is to analyse tool performance during drilling of IN718 using conventional metal working fluids (MWF) and cryogenic cooling conditions, and correlate it with the thermo-me- chanical phenomena. This study is conducted with standard coated cemented carbide twist drills, designed to work with MWF. The results show that drill performance under cryogenic cooling is strongly affected by its geometry. The axial force, drilling torque and tool wear/failure are higher under cryogenic cooling when compared to conventional MWF. Therefore, in order to take advantage of the cryo- genic machining, new drill design is required, which cur- rently is not available on the market.Mecachrom

Surface integrity in dry and cryogenic machining of AZ31B Mg alloy with varying cutting edge radius tools

Surface integrity of machined products has a critical impact on their functional performance. Magnesium alloys are lightweight materials for transportation industry and are also emerging as a potential material for temporary biomedical implants. However, their unsatisfactory corrosion resistance limits their application to a great extent. Surface integrity factors, such as grain size, crystallographic orientation and residual stresses, were reported to have significant influence on corrosion resistance of AZ31 Mg alloys. In this study, AZ31B Mg discs were orthogonally turned using cutting tools with two edge radii under both dry and cryogenic conditions. The influence of cutting edge radius and cooling method on surface integrity was investigated. Cryogenic machining using a large edge radius tool led to a thicker grain refinement layer, larger compressive residual stresses and stronger intensity of basal texture, which may remarkably enhance the corrosion performance of magnesium alloys.info:eu-repo/semantics/publishedVersio

Extracellular alpha-synuclein: Sensors, receptors, and responses

Synucleinopathies are a group of progressive neurodegenerative diseases known for the accumulation of insoluble aggregates containing the protein alpha-synuclein (aSyn). Recently, it has been assumed that pathology spreads in the brain during disease progression, implying that, at some point in the process, aSyn may exist outside of cells. In this context, extracellular-aSyn (e-aSyn) might transduce signals to the inside of the cells it interacts with, and/or be internalized by different types of cells through the extracellular matrix. Both negatively charged lipids and membrane receptors have been hypothesized as modulators of the loss of cellular homeostasis and cytotoxicity, and of the internalization of e-aSyn. Internalized e-aSyn causes the disruption of multiple cellular processes such as the autophagy lysosomal pathway (ALP), mitochondrial function, endoplasmic reticulum (ER)-stress, UPR activation, or vesicular transport. These processes happen not only in neurons but also in glial cells, activating inflammatory or anti-inflammatory pathways that can affect both neuronal function and survival, thereby affecting disease progression. In this review, we explore possible effects e-aSyn, all the way from the extracellular matrix to the nucleus. In particular, we highlight the glial-neuronal relationship as this is particularly relevant in the context of the spreading of aSyn pathology in synucleinopathies

Restauração de um dente anterior fracturado e encerramento de diastemas: caso clínico

info:eu-repo/semantics/publishedVersio

Chemical synthesis of site-selective advanced glycation end products in α-synuclein and its fragments

\ua9 2024 The Royal Society of Chemistry.Advanced glycation end products (AGEs) arise from the Maillard reaction between dicarbonyls and proteins, nucleic acids, or specific lipids. Notably, AGEs are linked to aging and implicated in various disorders, spanning from cancer to neurodegenerative diseases. While dicarbonyls like methylglyoxal preferentially target arginine residues, lysine-derived AGEs, such as N(6)-(1-carboxymethyl)lysine (CML) and N(6)-(1-carboxyethyl)lysine (CEL), are also abundant. Predicting protein glycation in vivo proves challenging due to the intricate nature of glycation reactions. In vitro, glycation is difficult to control, especially in proteins that harbor multiple glycation-prone amino acids. α-Synuclein (aSyn), pivotal in Parkinson\u27s disease and synucleinopathies, has 15 lysine residues and is known to become glycated at multiple lysine sites. To understand the influence of glycation in specific regions of aSyn on its behavior, a strategy for site-specific glycated protein production is imperative. To fulfill this demand, we devised a synthetic route integrating solid-phase peptide synthesis, orthogonal protection of amino acid side-chain functionalities, and reductive amination strategies. This methodology yielded two disease-related N-terminal peptide fragments, each featuring five and six CML and CEL modifications, alongside a full-length aSyn protein containing a site-selective E46CEL modification. Our synthetic approach facilitates the broad introduction of glycation motifs at specific sites, providing a foundation for generating glycated forms of synucleinopathy-related and other disease-relevant proteins