Numerical prediction of delamination in CFRP drilling

Delamination is one of the undesired effects of machining using non appropriate cutting parameters or worn drill. Finite element modeling of drilling of Carbon Fiber Reinforced Polymer (CFRP) composites is an interesting tool for damage prediction. Recently, complete modeling of the process including the rotatory movement of the drill, penetration in the composite plate and element erosion has been developed in the scientific literature. Computational cost of these complex models is a great disadvantage when comparing them with simplified models that consider the drill acting like a punch that pierces the laminate. In this paper both complete and simplified models were developed and compared in terms of delamination prediction. The simplified model, presenting reduced computational cost, slightly overestimates the delamination factor when compared with the complex model. The influence on delamination of thrust force, clamping area at the bottom surface of the laminate and the stacking sequence is studied using the simplified model.This work was supported by the Ministry of Economy and Competitiveness of Spain under the Project DPI2011-25999.Publicad

Experimental and numerical analysis of step drill bit performance when drilling woven CFRPs

This paper focuses on the influence of the step drill bit geometry on the damage induced during drilling Carbon Fiber Reinforced Polymer materials (CFRPs). Step geometry designed with the aim of avoiding composite damage in CFRPs drilling, is compared to conventional twist configuration. Despite the reduction of thrust force and torque observed when using the step drill, the delamination was only reduced at low feed rates. A numerical model developed for the step geometry was validated with experimental data demonstrating its ability to predict thrust force and delamination for different values of feed rate and cutting speed. Numerical model allowed the development of a parametrical study. Finally, using a response surface methodology a mechanistic model and surface diagrams have been presented in order to help in the selection of optimum variables minimizing drilling induced damage.The authors acknowledge the financial support for this work from the Ministry of Economy and Competitiveness of Spain under the project DPI2011-25999, FEDER program, and the FPI subprogram associated to the project previously mentioned with the reference BES-2012-055162

PILATES TRAINING INDUCES CHANGES IN THE TRUNK MUSCULATURE OF ADOLESCENTS

Introduction The Pilates Method may be an appropriate form of exercise for improving trunk muscle strength, which can be a predictor of pain and musculoskeletal problems. Objective The objective of this study was to assess the effects of the Pilates Method on muscle strength and endurance of the extensor and flexor muscles of the trunk in a group of adolescents. Methods The sample consisted of 101 high-school students divided into two groups: an experimental group (EG=81) and a control group (CG=20). The intervention was carried out twice a week for six weeks. Each session lasted 55 minutes, and was divided into three parts: warm-up, main part, and cool down. Muscle strength was assessed by the Sörensen Test and the Bench Trunk-curl Test. The paired sample T-test, the T- test for independent samples, and Pearson’s correlation coefficient were applied. The size of the effect (d) was determined. Results The EG showed significant improvements in both tests (+34.77 points; +18.55 points, respectively). No changes were observed in the CG. The effect size was high (d\u3e1.15) for both tests, which means that the results were improved in a large proportion of the participants. The control group showed a decline in strength of the trunk musculature. In the experimental group, both boys and girls showed significant improvements in both tests. This strength increase was enhanced for a large proportion of boys and girls (d\u3e1.15). The effect size was high (d\u3e1.15) for both tests and for both sexes. Conclusion Six-weeks after implementing the Pilates Method in Physical Education lessons, the muscle strength of the flexor and extensor muscles of the trunk in adolescents was improved. Level of Evidence II; Therapeutic studies-Investigation of treatment results

Numerical analysis of the influence of tool wear and special cutting geometry when drilling woven CFRPs

CFRPs drilling is a common process in the aerospace industry carried out prior to components assembly. Machining induced damage leads to significant percentage of component rejection. Damage extension strongly depends on drilling geometry and cutting parameters. Fresh drill geometry changes with cutting time due to the wear progression and the risk for hole quality is enhanced as cutting progresses. The influence of wear on hole quality has been analyzed in the literature using mainly an experimental approach. Simulation of drilling process is an effective method that can be used to optimize drill geometry and process parameters in order to control hole quality and analyze the drill wear evolution. In this paper a finite element model for drilling woven CFRPs, reproducing both fresh and worn tools, is presented. Two different point angles considering fresh and honned edge were modeled. A progressive intra-laminar failure model based on the Chang and Chang model is considered. Cohesive elements allowed the analysis of inter-laminar damage (delamination). The model demonstrated its ability to predict thrust force and delamination for different values of feed rate and cutting speed. Model predictions show the influence of tool geometry (including variations induced due to wear) on delamination.This study has been developed under the financial support of the Ministry of Economy and Competitiveness of Spain under the projects DPI2011-25999 and DPI2013-41094-R, and the FPI subprogram associated to the project DPI2011-25999 with the reference BES-2012-055162

The Glial Cell of Human Cutaneous Sensory Corpuscles: Origin, Characterization, and Putative Roles

Sensory corpuscles of human skin are structures located at the peripheral end of the mechanoreceptive neurons and function as low-threshold mechanoreceptors (LTMRs). In its structure, in addition to the axon, there are glial cells, not myelinating, that are organized in different ways according to the morphotype of sensitive corpuscle, forming the so-called laminar cells of Meissner’s corpuscles, the laminar cells of the inner core of Pacinian corpuscles, or cells of the inner core in Ruffini’s corpuscles. Classically the glial cells of sensory corpuscles have been considered support cells and passive in the process of mechanotransduction. However, the presence of ion channels and synapses-like systems between them and the axon suggests that corpuscular glial cells are actively involved in the transformation of mechanical into electrical impulses. This chapter is an update on the origin, development, cytoarchitecture, and protein profile of glial cells of sensitive corpuscles especially those of human glabrous skin

The Cutaneous Biopsy for the Diagnosis of Peripheral Neuropathies: Meissner’s Corpuscles and Merkel’s Cells

Cutaneous biopsy is a complementary method, alternative to peripheral nerve biopsy, for the analysis of nerve involvement in peripheral neuropathies, systemic diseases, and several pathologies of the central nervous system. Most of these neuropathological studies were focused on the intraepithelial nerve fibers (thin-myelinated Aδ fibers and unmyelinated C fibers), and few studies investigated the variations in dermal innervation, that is, large myelinated fibers, Merkel’s cell-neurite complexes, and Meissner’s corpuscles. Here, we updated and summarized the current data about the quantitative and qualitative changes that undergo MCs and MkCs in peripheral neuropathies. Moreover, we provide a comprehensive rationale to include MCs in the study of cutaneous biopsies when analyzing the peripheral neuropathies and aim to provide a protocol to study them

A Tangible Educative 3D Printed Atlas of the Rat Brain

[EN] In biology and neuroscience courses, brain anatomy is usually explained using Magnetic Resonance (MR) images or histological sections of different orientations. These can show the most important macroscopic areas in an animals¿ brain. However, this method is neither dynamic nor intuitive. In this work, an anatomical 3D printed rat brain with educative purposes is presented. Hand manipulation of the structure, facilitated by the scale up of its dimensions, and the ability to dismantle the ¿brain¿ into some of its constituent parts, facilitates the understanding of the 3D organization of the nervous system. This is an alternative method for teaching students in general and biologists in particular the rat brain anatomy. The 3D printed rat brain has been developed with eight parts, which correspond to the most important divisions of the brain. Each part has been fitted with interconnections, facilitating assembling and disassembling as required. These solid parts were smoothed out, modified and manufactured through 3D printing techniques with poly(lactic acid) (PLA). This work presents a methodology that could be expanded to almost any field of clinical and pre-clinical research, and moreover it avoids the need for dissecting animals to teach brain anatomy.This work was supported in part by the Spanish Ministerio de Economia y Competitividad (MINECO) and FEDER funds under grants BFU2015-64380-C2-2-R (D.M.) and BFU2015-64380-C2-1-R and EU Horizon 2020 Program 668863-SyBil-AA grant (S.C.). S.C. acknowledges financial support from the Spanish State Research Agency, through the "Severo Ochoa" Programme for Centres of Excellence in R&D (ref. SEV-2013-0317). D.R.Q. was supported by grant "Ayudas para la formacion de personal investigador (FPI)" from the Vicerrectorado de Investigacion, Innovacion y Transferencia of the Universitat Politecnica de Valencia.Quiñones, DR.; Ferragud-Agulló, J.; Pérez Feito, R.; García Manrique, JA.; Canals-Gamoneda, S.; Moratal, D. (2018). A Tangible Educative 3D Printed Atlas of the Rat Brain. Materials. 11(9):1531-1542. https://doi.org/10.3390/ma11091531S15311542119Perrin, R. J., Fagan, A. M., & Holtzman, D. M. (2009). Multimodal techniques for diagnosis and prognosis of Alzheimer’s disease. Nature, 461(7266), 916-922. doi:10.1038/nature08538Linden, D. E. J. (2012). The Challenges and Promise of Neuroimaging in Psychiatry. Neuron, 73(1), 8-22. doi:10.1016/j.neuron.2011.12.014Teipel, S., Drzezga, A., Grothe, M. J., Barthel, H., Chételat, G., Schuff, N., … Fellgiebel, A. (2015). Multimodal imaging in Alzheimer’s disease: validity and usefulness for early detection. 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Plasmolipin regulates basolateral-to-apical transcytosis of ICAM-1 and leukocyte adhesion in polarized hepatic epithelial cells

Apical localization of Intercellular Adhesion Receptor (ICAM)-1 regulates the adhesion and guidance of leukocytes across polarized epithelial barriers. Here, we investigate the molecular mechanisms that determine ICAM-1 localization into apical membrane domains of polarized hepatic epithelial cells, and their effect on lymphocyte-hepatic epithelial cell interaction. We had previously shown that segregation of ICAM-1 into apical membrane domains, which form bile canaliculi and bile ducts in hepatic epithelial cells, requires basolateral-to-apical transcytosis. Searching for protein machinery potentially involved in ICAM-1 polarization we found that the SNARE-associated protein plasmolipin (PLLP) is expressed in the subapical compartment of hepatic epithelial cells in vitro and in vivo. BioID analysis of ICAM-1 revealed proximal interaction between this adhesion receptor and PLLP. ICAM-1 colocalized and interacted with PLLP during the transcytosis of the receptor. PLLP gene editing and silencing increased the basolateral localization and reduced the apical confinement of ICAM-1 without affecting apicobasal polarity of hepatic epithelial cells, indicating that ICAM-1 transcytosis is specifically impaired in the absence of PLLP. Importantly, PLLP depletion was sufficient to increase T-cell adhesion to hepatic epithelial cells. Such an increase depended on the epithelial cell polarity and ICAM-1 expression, showing that the epithelial transcytotic machinery regulates the adhesion of lymphocytes to polarized epithelial cells. Our findings strongly suggest that the polarized intracellular transport of adhesion receptors constitutes a new regulatory layer of the epithelial inflammatory respons