T.08 - Engrenagens de parafuso sem-fim

Neste documento aborda-se o tema das engrenagens de parafuso sem-fim, o qual é lecionado no âmbito da unidade curricular Órgãos de Máquinas II, do curso de Mestrado Integrado em Engenharia Mecânica da Universidade do Minho. Com efeito, inicia-se este assunto com uma breve introdução, após a qual se apresenta o estudo relativo à geração do dente. Seguidamente faz-se uma breve referência aos perfis dos filetes deste tipo de engrenagens. De seguida apresenta-se a principal nomenclatura utilizada em engrenagens de parafuso sem-fim, apresentando-se o estudo da relação de transmissão. Seguidamente, estudam-se as principais relações geométricas a ter em consideração neste tipo de engrenagens. Depois dá-se particular relevo aos parâmetros de desempenho de engrenagens de parafuso sem-fim, nomeadamente a relação de condução e o rendimento. Finalmente, termina-se este documento com uma breve lista de questões de revisão de conhecimentos, assim como uma lista de referências bibliográficas

A influência de um campo magnético estático no escoamento sanguíneo com nanopartículas magnéticas

De forma a realizar estudos de escoamentos em microcanais e avaliar a influência das nanopartículas, sob a ação de um campo magnético estático, na espessura da camada de plasma, foram produzidas nanoparticulas de óxido de ferro por síntese solvotérmica, sendo posteriormente colocadas em suspensão num fluido fisiológico constituído por eritrócitos. Verificou-se que as nanopartículas com características magnéticas proporcionam a diminuição da espessura da camada de plasma, um comportamento contrário ao observado com nanopartículas sem características magnéticas.Os autores agradecem à FCT, COMPETE, QREN e União Europeia (FEDER) pelo financiamento através dos seguintes projetos: PTDC/SAU-BEB/105650/2008, PTDC/SAU-BEB/108728/2008, PTDC/EMEMFE/ 099109/2008, PEst-C/EQB/LA0020/2011 e PTDC/SAU-ENB/116929/2010

Analysis of a vegetable oil performance in a milling process by MQL lubrication

In this work, we carried out a comparison between the dry machining of an aluminum block with conventional cutting oil and a block with vegetable oil. The two oils had different flow rates. Using the Taguchi method, it was possible to determine the matrices for optimizing the best parameters for each group of tests. Then, we studied the utility of using vegetable oil as a cutting lubricant. We found that the vegetable oil studied in this work had good properties in terms of reducing cutting temperatures but was less effective than conventional cutting oil in reducing the surface roughness of the machined part. Tribological tests were carried out to understand the influence of the selected lubricants in reducing friction and wear. After the sliding experiments, which were performed without lubrication in the presence of the same lubricants that were used in the machining tests and in the presence of distilled water, we concluded that vegetable oil has satisfactory lubricating properties that are similar to those of the conventional cutting fluid, indicating a potential for consideration as an effective alternative to the conventional cutting fluid, with economic, environmental, and health advantages.Financial support was provided by Portugal’s national funding FCT/MCTES (PIDDAC) to Centro de Investigação de Montanha (CIMO) (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020). Additionally, this work was partially supported by Portuguese FCT, under the reference projects UIDB/04077/2020, UIDB/00532/2020 and UIDB/04436/2020. This research was also partially funded by EXPL2021CIMO_01. Inês Afonso acknowledges the financial support of CIMO through EXPL2021CIMO_01.info:eu-repo/semantics/publishedVersio

45S5 BAG-Ti6Al4V structures: The influence of the design on some of the physical and chemical interactions that drive cellular response

This work was supported by FCT (Fundação para a Ciência e Tecnologia) through the grants SFRH/BPD/112111/2015, SFRH/BD/128657/2017, PD/BDE/127836/2016, SFRH/BPD/97701/2013, SFRH/ BD/141056/2018, SFRH/BD/140191/2018 and the projects PTDC/EMSTEC/5422/2014 and NORTE-01-0145-FEDER-000018-HAMaBICo. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.Multi-material Ti6Al4V cellular structures impregnated with 45S5 bioactive glass were designed and produced using Selective LaserMelting (SLM), an additive manufacturing technique, combinedwith Press and Sintering focusing on load bearing components like hip implants. These structures were designed to combine Ti6Al4V mechanical properties and promote bone ingrowth into the structure as the bioactive material (45S5) is being absorbed and replaced by newly formed bone. The influence of these structures design on some of the physical and chemical aspects that drive cellular response was assessed. Roughness, wettability, bioactive glass quantity and quality on the structures after processing and the pH measured during cell culture (as a consequence of bioactive glass dissolution) were evaluated and correlated with cellular viability, cellular distribution, morphology and proliferation on the surface and inside the structures.info:eu-repo/semantics/publishedVersio

Analysis of a vegetable oil performance in a milling process by MQL Lubrication

In this work, we carried out a comparison between the dry machining of an aluminum block with conventional cutting oil and a block with vegetable oil. The two oils had different flow rates. Using the Taguchi method, it was possible to determine the matrices for optimizing the best parameters for each group of tests. Then, we studied the utility of using vegetable oil as a cutting lubricant. We found that the vegetable oil studied in this work had good properties in terms of reducing cutting temperatures but was less effective than conventional cutting oil in reducing the surface roughness of the machined part. Tribological tests were carried out to understand the influence of the selected lubricants in reducing friction and wear. After the sliding experiments, which were performed without lubrication in the presence of the same lubricants that were used in the machining tests and in the presence of distilled water, we concluded that vegetable oil has satisfactory lubricating properties that are similar to those of the conventional cutting fluid, indicating a potential for consideration as an effective alternative to the conventional cutting fluid, with economic, environmental, and health advantages.Financial support was provided by Portugal’s national funding FCT/MCTES (PIDDAC) to Centro de Investigação de Montanha (CIMO) (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020). Additionally, this work was partially supported by Portuguese FCT, under the reference projects UIDB/04077/2020, UIDB/00532/2020 and UIDB/04436/2020. This research was also partially funded by EXPL2021CIMO_01. Inês Afonso acknowledges the financial support of CIMO through EXPL2021CIMO_01

Mortars from the palace of Knossos in Crete, Greece: A multi-analytical approach

The study of building materials constituting cultural heritage is fundamental to understand their characteristics and predict their behavior. When considering materials from archaeological sites, their characterization can provide not only relevant information for a broader understanding of the site and its importance and significance but can also increase knowledge about ancient materials and their performance. The Palace of Knossos is a very important archaeological site in the European history context, and its preservation benefits from the characterization of the constituent materials. Samples of mortars from this monument were collected under the scope of the H2020 HERACLES project, where a multi-analytical approach was chosen using established protocols for the different sample typologies. Instrumental techniques such as optical microscopy (OM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and simultaneous thermogravimetry and differential thermal analysis (TG–DTA) were used for the chemical, mineralogical, and morphological characterization of these mortar samples. The results indicate that the majority are lime mortars, both aerial and hydraulic, but gypsum-based mortars were also identified. Differences in the chemical composition of the samples in distinct areas of the monument allowed us to reflect on the variety of materials used in the construction of the Palace of Knossos.publishersversionpublishe

A new model of laryngitis: neuropeptide, cyclooxygenase, and cytokine profile

Objectives/Hypothesis: To develop and characterize a new model of laryngeal inflammation by analyzing the presence of neurogenic peptides and expression of cyclooxygenases (COX) and cytokines in the mucosa.Study Design: Laryngitis induced by nasogastric intubation (NGI) was evaluated by histopathologic changes of the mucosa, alterations in calcitonin gene related peptide (CGRP) and substance P (SP) neuropeptides in sensory fibers, and COX-1,2, and cytokine (interleukin [IL]-1, IL-6, IL-10, tumor necrosis factor [TNF]-alpha) expression in the laryngeal mucosa.Methods: Rats submitted to NGI for 1 to 5 weeks were compared with controls. Laryngeal sections were immunostained for stereologic analysis of SP and CGRP fiber density and number of mucosal cells expressing COX-2. Alterations in inflammatory mediators were evaluated by quantitative reverse-transcriptase polymerase chain reaction.Results: NGI induced metaplasia of the epithelium and narrowing of the laryngeal lumen because of hypertrophy of laryngeal glandules and edema. An initial decrease in CGRP- and SP-immunoreactive fibers in the laryngeal mucosa (1-3 wk) was reverted with time (5 wk). COX-2 expression in mucosal cells increased progressively, reaching a maximum level at 5 weeks, and was observed in mononuclear immune cells, which is indicative of a chronic inflammatory process. In regard to mRNA expression levels of inflammatory mediators, TNF-alpha was increased during the 5 week NGI, and IL-10 decreased during the 5 weeks,whereas IL-beta, IL-6, and COX-2 increased in the first 1 to 2 weeks and returned to baseline at 5 weeks.Conclusions: This NGI model results in laryngeal chronic inflammation without direct mechanical aggression of the mucosa and may contribute to the study of future therapeutic approaches to this pathology.FEDERFundação para a Ciência e Tecnologia (FCT) - POCTI/NSE/46399/2002Fundação Calouste Gulbenkian - projecto nº 7455

The selective COX-2 inhibitor etoricoxib reduces acute inflammatory markers in a model of neurogenic laryngitis but loses its efficacy with prolonged treatment

The selective COX-2 inhibitor Etoricoxib reduces acute inflammatory markers in a model of neurogenic laryngitis but loses its efficacy with prolonged treatment.OBJECTIVE: A randomised experimental study was used to evaluate the therapeutic effect of a selective cyclooxygenase-2 (COX-2) inhibitor in neurogenic laryngitis. MATERIALS AND METHODS: Male Wistar Han rats were subjected to the nasogastric intubation model (NGI) of laryngitis for 1 and 2 weeks. The NGI animals were divided into three groups: (1) treated with COX-2 inhibitor Etoricoxib, (2) vehicle and (3) non-intubated animals. A fourth group of animals was submitted to NGI only. Laryngeal sections were immunostained for substance P (SP) and calcitonin gene-related peptide (CGRP) fibre-immunoreactivity (IR) and quantification of COX-2 positive cells through stereological analysis. The expression of COX-2, interleukins IL-1beta, IL-6, IL-10 and tumour necrosis factor-alpha (TNF-alpha) was determined by quantitative real time QRT-PCR. TREATMENT: Etoricoxib (6 mg/kg/day) was prepared in 0.9% sterile saline with 5% glucose (vehicle) and administered daily during 1 or 2 weeks. RESULTS: Treatment for 1 week with Etoricoxib attenuated the CGRP-IR fibre depletion, the COX-2-IR increased cell number and the TNF-alpha and COX-2 mRNA increased levels induced by NGI. Two weeks of treatment had no beneficial effect. CONCLUSIONS: Etoricoxib is effective in neurogenic laryngitis for limited periods of administration, indicating that selective COX-2 inhibitors should be evaluated in the future.This study was supported by Fundacao Calouste Gulbenkian Project No 74551 and Fundacao Grunenthal (Portugal)

Pre-clinical assessment of Roflumilast therapy in a thoracic model of spinal cord injury

The failure of axons to regenerate after a spinal cord injury (SCI) remains one of the greatest challenges in neuroscience. The initial mechanical trauma is followed by a secondary injury cascade, creating a hostile microenvironment, which not only is not permissive to regeneration but also leads to further damage. One of the most promising approaches for promoting axonal regeneration is to maintain the levels of cyclic adenosine monophosphate (cAMP), specifically by a phosphodiesterase-4 (PDE4) inhibitor expressed in neural tissues. Therefore, in our study, we evaluated the therapeutic effect of an FDA-approved PDE4 inhibitor, Roflumilast (Rof), in a thoracic contusion rat model. Results indicate that the treatment was effective in promoting functional recovery. Rof-treated animals showed improvements in both gross and fine motor function. Eight weeks post-injury, the animals significantly recovered by achieving occasional weight-supported plantar steps. Histological assessment revealed a significant decrease in cavity size, less reactive microglia, as well as higher axonal regeneration in treated animals. Molecular analysis revealed that IL-10 and IL-13 levels, as well as VEGF, were increased in the serum of Rof-treated animals. Overall, Roflumilast promotes functional recovery and supports neuroregeneration in a severe thoracic contusion injury model and may be important in SCI treatment.This research was supported by Prémios Santa Casa Neurociências—Prize Melo e Castro for Spinal Cord Injury Research (MC-18-2021) and by national funds, through the Foundation for Science and Technology (FCT)—project PTDC/MED-FAR/29751/2017, project UIDB/50026/2020 and UIDP/50026/2020.We would like to acknowledge the financial support by the Foundation for Science and Technology to the following authors: RL (PD/BDE/127836/2016), JRC (SFRH/BD/145860/2019) and NAS (CEECIND/04794/2007). We would like to acknowledge the support of the ICVS Scien tific Microscopy Platform, members of the national infrastructure PPBI—Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122)

Targeting p53 for melanoma treatment: counteracting tumour proliferation, dissemination and therapeutic resistance

Melanoma is the deadliest form of skin cancer, primarily due to its high metastatic propensity and therapeutic resistance in advanced stages. The frequent inactivation of the p53 tumour suppressor protein in melanomagenesis may predict promising outcomes for p53 activators in melanoma therapy. Herein, we aimed to investigate the antitumor potential of the p53-activating agent SLMP53-2 against melanoma. Two- and three-dimensional cell cultures and xenograft mouse models were used to unveil the antitumor activity and the underlying molecular mechanism of SLMP53-2 in melanoma. SLMP53-2 inhibited the growth of human melanoma cells in a p53-dependent manner through induction of cell cycle arrest and apoptosis. Notably, SLMP53-2 induced p53 stabilization by disrupting the p53–MDM2 interaction, enhancing p53 transcriptional activity. It also promoted the expression of p53-regulated microRNAs (miRNAs), including miR-145 and miR-23a. Moreover, it displayed anti-invasive and antimigratory properties in melanoma cells by inhibiting the epithelial-to-mesenchymal transition (EMT), angiogenesis and extracellular lactate production. Importantly, SLMP53-2 did not induce resistance in melanoma cells. Additionally, it synergized with vemurafenib, dacarbazine and cisplatin, and resensitized vemurafenib-resistant cells. SLMP53-2 also exhibited antitumor activity in human melanoma xenograft mouse models by repressing cell proliferation and EMT while stimulating apoptosis. This work discloses the p53-activating agent SLMP53-2 which has promising therapeutic potential in advanced melanoma, either as a single agent or in combination therapy. By targeting p53, SLMP53-2 may counteract major features of melanoma aggressiveness.This work received financial support from PT national funds (FCT/MCTES, Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through LAQV/REQUIMTE (UID/QUI/50006/2020), iMed.ULisboa (UIDB/04138/2020), and PTDC/QUIQOR/29664/2017, PTDC/MEC-ONC/32018/2017. We thank FCT for the fellowships SFRH/BD/ 128673/2017 (J. Loureiro), 2020.04613.BD (J. Calheiros), PD/BD/143126/2019 (V. Barcherini)