Towards understanding the cutting and fracture mechanism in ceramic matrix composites

Ceramic Matrix Composites (CMCs) are increasingly used for the manufacture of high-value parts for several industries such as the aerospace, nuclear and automotive. Nevertheless, their heterogenic, anisotropic and brittle nature make difficult to characterise the machining process and therefore, an in-depth understanding of the cutting mechanics is needed. In this regard, this paper aims to understand the different behaviours of CMCs while employing orthogonal cutting. The first part of this article proposes a novel theoretical approach to explain the different types of cutting behaviours (fracture and shear cutting) based on the inelastic and orthotropic properties of the CMC's by using a high imaging system and measuring the cutting forces. The second part aims to understand the cutting and fracture mechanism by developing for the first time a specific analytical model for each of the three main orthotropic orientations, defined by the three main relative fibre orientations respect to the feed direction, which are found in cutting of CMCs. This is approached by the calculation of the specific cutting energy needed to fracture the CMC's during cutting (energy release rate, Gc) using fracture mechanics and cutting theories. This analytical model has been successfully validated for a Carbon/Carbon composite with the experimental data obtained for the brittle cutting and by introducing the concept of a rising R-curve in cutting models. Moreover, comparing the results obtained for the energy release rate for the brittle and semi-ductile mode, it is observed that the material experiences an important change in the energy release rate according to the brittle-to-semi-ductile transition occurring while reducing the depth of cut. Finally, a novel monitoring method based on the vibrations of the sample has been found successful to understand the type of crack formation appearing while cutting CMCs

The PENELOPE physics models and transport mechanics. Implementation into Geant4

A translation of the penelope physics subroutines to C++, designed as an extension of the Geant4 toolkit, is presented. The Fortran code system penelope performs Monte Carlo simulation of coupled electron-photon transport in arbitrary materials for a wide energy range, nominally from 50 eV up to 1 GeV. Penelope implements the most reliable interaction models that are currently available, limited only by the required generality of the code. In addition, the transport of electrons and positrons is simulated by means of an elaborate class II scheme in which hard interactions (involving deflection angles or energy transfers larger than pre-defined cutoffs) are simulated from the associated restricted differential cross sections. After a brief description of the interaction models adopted for photons and electrons/positrons, we describe the details of the class-II algorithm used for tracking electrons and positrons. The C++ classes are adapted to the specific code structure of Geant4. They provide a complete description of the interactions and transport mechanics of electrons/positrons and photons in arbitrary materials, which can be activated from the G4ProcessManager to produce simulation results equivalent to those from the original penelope programs. The combined code, named PenG4, benefits from the multi-threading capabilities and advanced geometry and statistical tools of Geant4

The human area postrema and other nuclei related to the emetic reflex express cAMP phosphodiesterases 4B and 4D

Phosphodiesterase 4 (PDE4) inhibitors, i.e. rolipram, are being extensively investigated as therapeutic agents in several diseases. Emesis is one of the most common side effects of PDE4 inhibitors. Given the fact that the area postrema is considered the chemoreceptor trigger zone for vomiting, the present study investigates the regional distribution and cellular localization of the four gene transcripts of the PDE4 subfamily (PDE4A, PDE4B, PDE4C and PDE4D) in human brainstem. In situ hybridization histochemistry was used to locate the mRNA distribution of the four PDE4 subfamilies in the area postrema and related nuclei of human postmortem brainstem. We have found that in the brainstem PDE4B and PDE4D mRNA expression is abundant and distributed not only in neuronal cells, but also in glial cells, and on blood vessels. The hybridization signals for PDE4B and PDE4D mRNAs in the area postrema were stronger than those in any other nuclei in the brainstem. They were also found in vomiting-related nuclei such as the nucleus of the solitary tract and the dorsal vagal motor nucleus. These findings suggest that cAMP signaling modification in the area postrema could mediate the emetic effects of PDE4 inhibitors in human brainstem.This work was supported by grants from Ministerio de Educación y Ciencia and Fondo Europeo de Desarrollo Regional (SAF2006-10243). F.M. was on sabbatical leave from Hirosaki University School of Medicine. S.P.-T. was recipient of a predoctoral fellowship from CIRIT (Generalitat de Catalunya).Peer Reviewe

African mountain thistles: generic delimitation problems analyzed with NGS

Póster presentado en el III Simposio Anual de Botánica Española celebrado en el Institut Botànic de Barcelona, 25-26 de noviembre de 202

Enquesta preliminar de càries dentària en la població escolar del Priorat, la Ribera d'Ebre i la Terra Alta: objectius i metodologia (I.ª part)

Podeu consultar la segona part de l'article a: http://hdl.handle.net/2445/112051Hi ha una notable escassetat de dades i d'estudis epidemiològics sobre la magnitud del problema de la càries dentària a Catalunya i a la resta d'Espanya. L'únic treball realitzat a Espanya prou important per poder extreure'n resultats significatius és el que va realitzar la Direcció General de Sanitat, durant els anys 1968-1969, entre la població escolar..

Resultats de l'enquesta preliminar de càries dentària en la població escolar del Priorat, Ribera d'Ebre i Terra Alta (2.ª part)

Podeu consultar la primera part de l'article a: http://hdl.handle.net/2445/106530Hi ha una elevada prevalença de càries dentària en la població d'edat escolar d'aquestes tres comarques. Així, la prevalença de càries en dents permanents és del 71,7%. Les xifres són encara més preocupants si considerem la càries en dents temporals. En aquest cas, el 91% dels nens de 6 a 14 anys té algun tipus de càries

Age-dependent maintenance of motor control and corticostriatal innervation by death receptor 3

Death receptor 3 is a proinflammatory member of the immunomodulatory tumor necrosis factor receptor superfamily, which has been implicated in several inflammatory diseases such as arthritis and inflammatory bowel disease. Intriguingly however, constitutive DR3 expression has been detected in the brains of mice, rats, and humans, although its neurological function remains unknown. By mapping the normal brain expression pattern of DR3, we found that DR3 is expressed specifically by cells of the neuron lineage in a developmentally regulated and region-specific pattern. Behavioral studies on DR3-deficient (DR3(ko)) mice showed that constitutive neuronal DR3 expression was required for stable motor control function in the aging adult. DR3(ko) mice progressively developed behavioral defects characterized by altered gait, dyskinesia, and hyperactivity, which were associated with elevated dopamine and lower serotonin levels in the striatum. Importantly, retrograde tracing showed that absence of DR3 expression led to the loss of corticostriatal innervation without significant neuronal loss in aged DR3(ko) mice. These studies indicate that DR3 plays a key nonredundant role in the retention of normal motor control function during aging in mice and implicate DR3 in progressive neurological disease

A role for Oncostatin M in the impairment of glucose homeostasis in obesity

CONTEXT: Oncostatin M (OSM) plays a key role in inflammation, but its regulation and function during obesity is not fully understood. OBJECTIVE: The aim of this study was to evaluate the relationship of OSM with the inflammatory state that leads to impaired glucose homeostasis in obesity. We also assessed whether OSM immunoneutralization could revert metabolic disturbances caused by a high-fat diet (HFD) in mice. DESIGN: 28 patients with severe obesity were included and stratified into two groups: (1) glucose levels 100 mg/dL. White adipose tissue was obtained to examine OSM gene expression. Human adipocytes were used to evaluate the effect of OSM in the inflammatory response, and HFD-fed C57BL/6J mice were injected with anti-OSM antibody to evaluate its effects. RESULTS: OSM expression was elevated in subcutaneous and visceral fat from patients with obesity and hyperglycemia, and correlated with Glut4 mRNA levels, serum insulin, homeostatic model assessment of insulin resistance, and inflammatory markers. OSM inhibited adipogenesis and induced inflammation in human adipocytes. Finally, OSM receptor knockout mice had increased Glut4 mRNA levels in adipose tissue, and OSM immunoneutralization resulted in a reduction of glucose levels and Ccl2 expression in adipose tissue from HFD-fed mice. CONCLUSIONS: OSM contributes to the inflammatory state during obesity and may be involved in the development of insulin resistance

Increasing breast milk betaine modulates Akkermansia abundance in mammalian neonates and improves long-term metabolic health

Accelerated postnatal growth is a potentially modifiable risk factor for future obesity. To study how specific breast milk components contribute to early growth and obesity risk, we quantified one-carbon metabolism-related metabolites in human breast milk and found an inverse association between milk betaine content and infant growth. This association was replicated in an independent and geographically distinct cohort. To determine the potential role of milk betaine in modulating offspring obesity risk, we performed maternal betaine supplementation experiments in mice. Higher betaine intake during lactation increased milk betaine content in dams and led to lower adiposity and improved glucose homeostasis throughout adulthood in mouse offspring. These effects were accompanied by a transient increase in Akkermansia spp. abundance in the gut during early life and a long-lasting increase in intestinal goblet cell number. The link between breast milk betaine and Akkermansia abundance in the gut was also observed in humans, as infants exposed to higher milk betaine content during breastfeeding showed higher fecal Akkermansia muciniphila abundance. Furthermore, administration of A. muciniphila to mouse pups during the lactation period partially replicated the effects of maternal breast milk betaine, including increased intestinal goblet cell number, lower adiposity, and improved glucose homeostasis during adulthood. These data demonstrate a link between breast milk betaine content and long-term metabolic health of offspring.info:eu-repo/semantics/acceptedVersio