Modelling the Surface Roughness of Steel after Laser hardening by using 2D Visibility Network, Convolutional neural Networks and Genetic Programming

The surface characterization of materials after Robot Laser Hardening (RLH) is a technically demanding procedure. RLH is commonly used to harden parts, especially when subject to wear. By changing their surface properties, this treatment can offer several benefits such as lower costs for additional machining, no use of cooling agents or chemicals, high flexibility, local hardening, minimal deformation, high accuracy, and automated and integrated process in the production process. However, the surface roughness strongly depends on the heat treatment and parameters used in the process. This article used a network theory approach (i.e., the visibility network in 2D space) to analyze the surface roughness of tool steel EN100083-1 upon RLH. Specifically, two intelligent methods were merged in this investigation. Firstly, a genetic algorithm was applied to derive a relationship between the parameters of the robot laser cell and topological surface properties. Furthermore, convolutional neural networks allowed the assessment of surface roughness based on 2D photographic image

Carbide Type Influence on Tribological Properties of Hard Faced Steel Layer Part II- Experimental Results

In this paper is presented a preceding procedure that should be conducted in order to successfully regenerate damaged forging dies by the hard facing process. After the tool damage types identification, as well as their causes, we have chosen the procedure and the parameters of hard facing that we further corrected by conducting the test hard facings on models. Thus, we were able to relate the experimental results outputs with the repair technology, taking as a criterion the quality of the surface layers wear resistance such as friction coefficient and width of hard faced zone, hardness and its distribution in cross section, then microstructure of characteristic of hard faced zones, etc. This research points out significancy of tribological properties of certain types of carbides and their effects on metal matrix, in which carbides are embedded. Our tribological investigations have shown that the working life of the hard faced tool can be longer than that of the new tool

Carbide Type Influence on Tribological Properties of Hard Faced Steel Layer - Part I - Theoretical Considerations

This paper gives a theoretical review of influence of the most important alloying elements on steel, and review of the most important carbide-forming elements and states the conditions which elements should fulfill in order to be considered as carbide-forming. It primarily involves alloying elements which in the iron-carbon system can form simple, complex or special carbides, i.e. phases of interstitial and substitutive type. It also gives a review of carbide types that are formed during either production or reparatory hard facing of steel parts with different types of filler materials

Joint theoretical and experimental study on elastic electron scattering from bismuth

We report on experimental elastic differential and integral cross sections for electron scattering from bismuth. The energy range of those measurements is 10-100 eV, while the scattered electron angular range in the differential cross section data is 10 degrees-150 degrees. We also supplement our experimental results with theoretical data from our optical potential approach, in this case applying two different sets of scattering potentials to the problem. Good overall qualitative accord is typically observed between our measured and calculated results, particularly when allowance is made for the dimer contribution in the experimental atomic beam

Kinematic magnetic resonance imaging study of the brain stem and cervical cord by dynamic neck motion

Background: The aim was to examine the position of the brain stem and cervical cord following the neck flexion and extension. Materials and methods: The serial sagittal T2-weighted magnetic resonance imaging (MRI) sections of the cervical cord and brain stem were made in 6 volunteers. The images were mainly used to measure certain distances and angles of the brain stem and cervical cord in the neutral position, and then following the head and neck flexion and extension. Results: The measurements showed that the pons is slightly closer to the clivus following the neck flexion; the medulla oblongata is somewhat distant to the basion but closer to the odontoid process. At the same time, the spino-medullary angle diminishes in size. On the other hand, the upper cervical cord slightly approaches the posterior wall of the spinal canal, the lower cervical cord is closer to the anterior wall, while the angle between them is significantly larger in size. After the cervical cord extension, the rostral pons is somewhat distant to the clivus, whereas the caudal pons and the medulla are slightly closer to the clivus and the basion. At the same time, the spino-medullary angle diminishes in size. The cervical cord is mainly closer to the posterior wall of the spinal canal, whilst its angle is significantly smaller. Conclusions: The obtained results regarding the brain stem and cervical cord motion can be useful in the kinetic MRI examination of certain congenital disorders, degenerative diseases, and traumatic injuries of the craniovertebral junction and the cervical spine

Anatomy of the feeding arteries of the cerebral arteriovenous malformations

Background: Identification and anatomic features of the feeding arteries of the arteriovenous malformations (AVMs) is very important due to neurologic, radiologic, and surgical reasons.   Materials and methods: Seventy-seven patients with AVMs were examined by using a digital subtraction angiographic (DSA) and computerised tomographic (CT) examination, including three-dimensional reconstruction of the brain vessels. In addition, the arteries of 4 human brain stems and 8 cerebral hemispheres were microdissected.   Results: The anatomic examination showed a sporadic hypoplasia, hyperplasia, early bifurcation and duplication of certain cerebral arteries. The perforating arteries varied from 1 to 8 in number. The features of the leptomeningeal and choroidal vessels were presented. The radiologic examination revealed singular (22.08%), double (32.48%) or multiple primary feeding arteries (45.45%), which were dilated and elongated in 58.44% of the patients. The feeders most often originated from the middle cerebral artery (MCA; (23.38%), less frequently from the anterior cerebral artery (ACA; 12.99%), and the posterior cerebral artery (PCA; 10.39%). Multiple feeders commonly originated from the ACA and MCA (11.69%), the MCA and PCA (10.39%), the ACA and PCA (7.79%), and the ACA, MCA and PCA (5.19%). The infratentorial feeders were found in 9.1% of the AVMs. Contribution from the middle meningeal and occipital arteries was seen in 3.9% angiograms. Two cerebral arteries had a saccular aneurysm. The AVM haemorrhage appeared in 63.6% of patients.   Conclusions: The knowledge of the origin and anatomic features of the AVMs feeders is important in the explanation of neurologic signs, and in a decision regarding the endovascular embolisation, neurosurgical and radiosurgical treatments

Mechanocatalytic Depolymerization of Cellulose With Perfluorinated Sulfonic Acid Ionomers

Here, we investigated that the mechanocatalytic depolymerization of cellulose in the presence of Aquivion, a sulfonated perfluorinated ionomer. Under optimized conditions, yields of water soluble sugars of 90-97% were obtained using Aquivion PW98 and PW66, respectively, as a solid acid catalyst. The detailed characterization of the water soluble fraction revealed (i) the selective formation of oligosaccharides with a DP up to 11 and (ii) that depolymerization and reversion reactions concomitantly occurred during the mechanocatalytic process, although the first largely predominated. More importantly, we discussed on the critical role of water contained in Aquivion and cellulose on the efficiency of the mechanocatalytic process.CNRS Centre National de la Recherche ScientifiqueUniversity of PoitiersSpanish Ministerio de Economía y Competitividad (MINECO, CTQ2015-64425-C2-1-R)Junta de Andalucía ( FQM2012-1467

Psychotropic medication use among patients with a traumatic brain injury treated in the intensive care unit : a multi-centre observational study

Background Psychiatric sequelae after traumatic brain injury (TBI) are common and may impede recovery. We aimed to assess the occurrence and risk factors of post-injury psychotropic medication use in intensive care unit (ICU)-treated patients with TBI and its association with late mortality. Methods We conducted a retrospective multi-centre observational study using the Finnish Intensive Care Consortium database. We included adult TBI patients admitted in four university hospital ICUs during 2003-2013 that were alive at 1 year after injury. Patients were followed-up until end of 2016. We obtained data regarding psychotropic medication use through the national drug reimbursement database. We used multivariable logistic regression models to assess the association between TBI severity, treatment-related variables and the odds of psychotropic medication use and its association with late all-cause mortality (more than 1 year after TBI). Results Of 3061 patients, 2305 (75%) were alive at 1 year. Of these, 400 (17%) became new psychotropic medication users. The most common medication types were antidepressants (61%), antipsychotics (35%) and anxiolytics (26%). A higher Glasgow Coma Scale (GCS) score was associated with lower odds (OR 0.93, 95% CI 0.90-0.96) and a diffuse injury with midline shift was associated with higher odds (OR 3.4, 95% CI 1.3-9.0) of new psychotropic medication use. After adjusting for injury severity, new psychotropic medication use was associated with increased odds of late mortality (OR 1.19, 95% CI 1.19-2.17, median follow-up time 6.4 years). Conclusions Psychotropic medication use is common in TBI survivors. Higher TBI severity is associated with increased odds of psychotropic medication use. New use of psychotropic medications after TBI was associated with increased odds of late mortality. Our results highlight the need for early identification of potential psychiatric sequelae and psychiatric evaluation in TBI survivors.Peer reviewe

Supplementary data for the article: Mancic, L.; Djukic-Vukovic, A.; Dinic, I.; Nikolic, M. G.; Rabasovic, M. D.; Krmpot, A. J.; Costa, A. M. L. M.; Marinkovic, B. A.; Mojovic, L.; Milosevic, O. One-Step Synthesis of Amino-Functionalized up-Converting NaYF 4 :Yb,Er Nanoparticles for: In Vitro Cell Imaging. RSC Advances 2018, 8 (48), 27429–27437. https://doi.org/10.1039/c8ra04178d

Supplementary material for: [https://doi.org/10.1039/c8ra04178d]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2225

Desenvolvimento de um nanocompósito de matriz de polietileno (PEAD) com adição de nanocargas com expansão térmica negativa da família A2M3O12

Com a revolução nanotecnológica surgiu a possibilidade de manipulação dos materiais em níveis submicroscópicos. Três áreas da engenharia de materiais foram correlacionadas no presente trabalho: materiais poliméricos, nanomateriais e materiais cerâmicos com expansão térmica negativa, da reunião dessas áreas estão sendo desenvolvidos os nanocompósitos poliméricos para aplicações especiais, tais como na redução da expansão térmica positiva dos polímeros termoplásticos. Neste trabalho foi desenvolvido um novo nanocompósito com matriz de PEAD e nanocargas da família A2M3O12, especificamente o Al2Mo3O12 sintetizado pelo método de co-preciptação, uma rota de baixas energias térmicas. O processamento do nanocompósito foi realizado em uma micro-extrusora de 2 roscas e o material foi injetado em um molde de corpos de prova de ensaios de tração, com percentuais em peso de nanocargas predefinidos em 0,5%, 1%, 2%, 3%, 4% e 5%. Foram realizadas caracterizações térmicas, com microscópio eletrônico e mecânicas dos corpos de prova, obtendo-se detalhamentos micro-nanoestruturais. Sob o aspecto mecânico o principal objetivo foi estudar e evidenciar uma não redução de propriedades mecânicas e investigar possíveis melhorias, que foram obtidas em seus módulos de elasticidade e limite de resistência mecânica. Comparando o módulo de Young e o limite de resistência do PEAD puro de 1,2 GPa e 26 MPa respectivamente, ficou evidente o aumento destas propriedades mecânicas em 27% e 7%, visto que foram alcançados valores de 1,65 GPa e 28 MPa, para a amostra com 2% em peso. Com isso o nanocompósito mostrou-se promissor com possibilidades de aplicações mecânicas substitucionais em relação aos materiais clássicos de componentes e peças atualmente usados