1,533 research outputs found
Wood-fiber reinforced bio-polymer composites as alternative materials for industrial applications
Wood-fiber reinforced bio-polymer composite (WFRBC) emerges as a promising material for many industrial applications due to its attractive properties. This work aims to evaluate the thermomechanical performance of WFRBCs, their benefits as alternative materials towards oil-based composites, current challenges, and potential applications within the automotive and construction industry.
This thesis is divided into four sections. The first covers the state-of-the-art of composites from raw material, fiber surface modification and processing technologiesâ point of view. In sequence, the second section discusses the importance and potential of switching traditional composites for bio-based composites within the automotive and construction industry, as well as their relevance related to WFRBCs. The third section includes the state-of-the-art of thermomechanical properties analysis by standardized testing methods. Lastly, bio-composites application cases found in the literature were selected, for performance evaluation mainly based on thermomechanical properties. The main benefits of bio-composites for replacement of traditional composites mainly made of synthetic reinforcements and polypropylene (PP) matrix were investigated. The composite performance analysis was performed focusing on its mechanical properties (tensile strength, tensile stiffness, flexural strength and impact strength) as well as the composite thermal stability.
From the performance evaluation of the WFRBCs considered in this work and their potential to replace traditional composites, promising results that confirm the possibility of switching traditional oil-based composites to this class of bio-composites were found. In this context, WFRBCs have shown competitive and, in some cases, even better mechanical properties in comparison with glass fiber PP composites that are extensively used in the automotive and construction industry
PercepçÔes de estudantes de Medicina sobre o estresse acadĂȘmico e a mentoria no seu enfrentamento: um estudo qualitativo
A formação mĂ©dica Ă© considerada estressante devido a fatores como: extensa carga horĂĄria, atividades prĂĄticas complexas, muito conteĂșdo e alta exigĂȘncia de dedicação. Programas de mentoria podem amenizar esse estresse acadĂȘmico. Com o objetivo de investigar a percepção dos estudantes de um programa de mentoria sobre o estresse da formação mĂ©dica e a mentoria como recurso de enfrentamento, desenhou-se um estudo do tipo transversal com metodologia qualitativa. Selecionaram-se 12 alunos e realizaram-se sessĂ”es de grupo focal. Os dados produzidos foram submetidos Ă anĂĄlise temĂĄtica, resultando em duas categorias de estressores â 1. ser estudante e 2. ambiente acadĂȘmico â e em duas categorias de elementos protetores â 1. autocuidado e 2. mentoria. A mentoria foi considerada recurso de enfrentamento por ser um espaço de reflexĂŁo e desenvolvimento de habilidades e comportamentos que aumentam competĂȘncias relacionais, alĂ©m de propiciar acolhimento, alĂvio psicolĂłgico, pertencimento e efeito tranquilizador
Estimated Age of the Universe in Fractional Cosmology
Our proposed cosmological framework, which is based on fractional quantum
cosmology, aims to address the issue of synchronicity in the age of the
universe. % Please check intended meaning is retained. To achieve this, we have
developed a new fractional CDM cosmological model. We obtained the
necessary formalism by obtaining the fractional Hamiltonian constraint in a
general minisuperspace. This formalism has allowed us to derive the fractional
Friedmann and Raychaudhuri equations for a homogeneous and isotropic cosmology.
Unlike the traditional de Sitter phase, our model exhibits a power-law
accelerated expansion in the late-time universe, when vacuum energy becomes
dominant. % Please check intended meaning is retained. By fitting the model's
parameters to cosmological observations, we determined that the fractional
parameter of L\'{e}vy equals . Additionally, we have calculated
the age of the universe to be 13.8196 Gyr. Furthermore, we have found that the
ratio of the age to Hubble time from the present epoch to the distant future is
finite and confined within the interval .Comment: 24 pages, 9 figure
Systematic Review and Correlations with HPV Status and Patient Survival
Funding: This study was financially supported by the Virology Laboratory from the Pathology Department of the Portuguese Oncology Institute of Lisboa IUIC/1168, with contributions by the Research Center of the Portuguese Oncology Institute of Porto (project no. PI86-CI-IPOP-66-2017), by Base Funding-UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology, and EnergyâLEPABEâfunded by national funds through the FCT/MCTES (PIDDAC), and Project 2SMART-engineered Smart materials for Smart citizens, with reference NORTE-01- 0145-FEDER-000054, supported by Norte Portugal Regional Operational Programme (NORTE 2020) under the PORTUGAL 2020 Partnership Agreement through the European Regional Development Fund (ERDF).PIK3CA mutations are believed to contribute to the pathogenesis of human papillomavirus (HPV)-associated head and neck squamous cell carcinomas (HNSCC). This study aims to establish the frequency of PIK3CA mutations in a Portuguese HNSCC cohort and to determine their association with the HPV status and patient survival. A meta-analysis of scientific literature also revealed widely different mutation rates in cohorts from different world regions and a trend towards improved prognosis among patients with PIK3CA mutations. DNA samples were available from 95 patients diagnosed with HNSCC at the Portuguese Institute of Oncology in Lisbon between 2010 and 2019. HPV status was established based on viral DNA detected using real-time PCR. The evaluation of PIK3CA gene mutations was performed by real-time PCR for four mutations (H1047L; E542K, E545K, and E545D). Thirty-seven cases were found to harbour PIK3CA mutations (39%), with the E545D mutation (73%) more frequently detected. There were no significant associations between the mutational status and HPV status (74% WT and 68% MUT were HPV (+); p = 0.489) or overall survival (OS) (3-year OS: WT 54% and MUT 65%; p = 0.090). HPV status was the only factor significantly associated with both OS and disease-free survival (DFS), with HPV (+) patients having consistently better outcomes (3-year OS: HPV (+) 65% and HPV (-) 36%; p = 0.007; DFS HPV (+) 83% and HPV (-) 43%; p = 0.001). There was a statistically significant interaction effect between HPV status and PIK3CA mutation regarding DFS (Interaction test: p = 0.026). In HPV (+) patients, PIK3CA wild-type is associated with a significant 4.64 times increase in the hazard of recurrence or death (HR = 4.64; 95% CI 1.02-20.99; p = 0.047). Overall, PIK3CA gene mutations are present in a large number of patients and may help define patient subsets who can benefit from therapies targeting the PI3K pathway. The systematic assessment of PIK3CA gene mutations in HNSCC patients will require further methodological standardisation.publishersversionpublishe
Arteriolar C4d in IgA Nephropathy:A Cohort Study
Rationale & Objective: Glomerular C4d (C4dG) as an indicator of the lectin pathway of complement activation in immunoglobulin A nephropathy (IgAN) has been associated with more severe kidney damage. Recent studies have suggested that vascular lesions in IgAN biopsy specimens with complement deposition are also associated with disease progression. We aimed to study the clinical significance of arteriolar C4d (C4dA) in IgAN kidney biopsy tissue. Study Design: Retrospective cohort study. Setting & Participants: Kidney biopsy specimens from 126 adults with IgAN diagnosed by Oxford classification criteria were stained using immunohistochemistry and classified according to C4dG and C4dA deposition. Additionally, vascular lesions including acute and chronic microangiopathy, arteriolar hyalinosis, and arterial intima fibrosis were characterized. Predictor: C4dA. Outcome: Progressive kidney disease, defined as a decline in estimated glomerular filtration rate by >= 50% or occurrence of kidney failure. Analytical Approach: The association of C4dA and C4dG with baseline clinical and histologic characteristics, as well as progressive kidney disease, were assessed with survival analysis using multivariable Cox regression analysis. Results: C4dA was identified in 21 (17%) patients and was associated with mean arterial pressure, arterial intima fibrosis, and chronic microangiopathy. C4dA was also significantly associated with C4dG and both were associated with progressive kidney disease. In regression analysis, C4dA remained significantly associated with progressive kidney disease after adjusting for other significant predictors, including baseline estimated glomerular filtration rate, mean arterial pressure, and the presence of crescents. Limitations: Findings based on the retrospective evaluation of a single center's experience, limited number of events, a small number of patients with a broad range of kidney disease stages, and use of immunohistochemistry rather than immunofluorescence to detect C4d. Conclusions: C4dA is a potential biomarker for disease progression in IgAN. It should be further investigated in larger cohorts to determine the value of C4dA in improving prediction of IgAN disease progression
Individual patient-data meta-analysis comparing clinical outcome in patients with ST-elevation myocardial infarction treated with percutaneous coronary intervention with or without prior thrombectomy. ATTEMPT study: A pooled Analysis of Trials on ThrombEctomy in acute Myocardial infarction based on individual PatienT data
Background: Available data from randomized trials on thrombectomy in patients with ST-elevation myocardial infarction (STEMI) have shown favorable trends in myocardial reper-fusion. However, few data are available on the effect of thrombectomy on clinical outcome. Thus we have designed a collaborative individual patient-data meta-analysis which aimed to assess the long-term clinical outcome in STEMI patients randomized to percutaneous coronary intervention (PCI) with or without thrombectomy. Method: After a thorough database search, the principal investigators of randomized trials comparing thrombectomy with standard PCI in patients with STEMI were contacted. Principal investigators as authors of 11 randomized studies agreed to participate and were asked to complete a structured database by providing a series of key pre-PCI clinical and angiographic data as well as the longest available clinical outcome of the patients enrolled in the corresponding trial. The primary end-point of this pooled analysis is the comparison of overall survival rates between patients randomized to PCI with thrombectomy or PCI without thrombectomy. The secondary end-points are survival free from myocardial infarction (MI), target lesion revascularization (TLR), major adverse coronary events (MACE: death + MI + TLR) and death + MI between patients randomized to PCI with thrombectomy or PCI without thrombectomy. A pre-defined subgroup analysis is planned considering the following variables: type of thrombectomy device used, diabetes, rescue PCI, IIb/IIIa-inhibitors use, time-to-reperfusion, infarct-related artery, and pre-PCI TIMI flow. Implications: This study will provide useful data on the effect of the reported improved myocardial perfusion associated with thrombectomy on the long-term clinical outcome in patients with STEMI. © 2009 De Vita et al, publisher and licensee Dove Medical Press Ltd
Bifidobacterium animalis subsp lactis HN019 presents antimicrobial potential against periodontopathogens and modulates the immunological response of oral mucosa in periodontitis patients
Objective To evaluate the effects of Bifidobacterium animalis subsp. lactis HN019 (HN019) on clinical periodontal parameters (plaque accumulation and gingival bleeding), on immunocompetence of gingival tissues [expression of beta-defensin (BD)-3, toll-like receptor 4 (TLR4), cluster of differentiation(CD)-57 and CD-4], and on immunological properties of saliva (IgA levels) in non-surgical periodontal therapy in generalized chronic periodontitis (GCP) patients. Adhesion to buccal epithelial cells (BEC) and the antimicrobial properties of HN019 were also investigated. Materials and methods Thirty patients were recruited and monitored clinically at baseline (before scaling and root planing-SRP) and after 30 and 90 days. Patients were randomly assigned to Test (SRP +Probiotic, n = 15) or Control (SRP+Placebo, n = 15) group. Probiotic lozenges were used for 30 days. Gingival tissues and saliva were immunologically analyzed. The adhesion of HN019 with or without Porphyromonas gingivalis in BEC and its antimicrobial properties were investigated in in vitro assays. Data were statistically analyzed (p<0.05). Results Test group presented lower plaque index (30 days) and lower marginal gingival bleeding (90 days) when compared with Control group. Higher BD-3, TLR4 and CD-4 expressions were observed in gingival tissues in Test group than in Control group. HN019 reduced the adhesion of P. gingivalis to BEC and showed antimicrobial potential against periodontopathogens. Conclusion Immunological and antimicrobial properties of B. lactis HN019 make it a potential probiotic to be used in non-surgical periodontal therapy of patients with GCP.Fil: Invernici, Marcos M.. Universidade de Sao Paulo; BrasilFil: Furlaneto, FlĂĄvia A. C.. Universidade de Sao Paulo; BrasilFil: Salvador, SĂ©rgio L. Universidade de Sao Paulo; BrasilFil: Ouwehand, Arthur C.. Dupont, Nutrition and Health; FinlandiaFil: Salminen, Seppo. University of Turku. Functional Foods Forum; FinlandiaFil: Mantziari, Anastasia. University of Turku. Functional Foods Forum; FinlandiaFil: Vinderola, Celso Gabriel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de LactologĂa Industrial. Universidad Nacional del Litoral. Facultad de IngenierĂa QuĂmica. Instituto de LactologĂa Industrial; ArgentinaFil: Ervolino, Edilson. SĂŁo Paulo State University. Division of Histology, Department of Basic Sciences, Dental School of Araçatuba; BrasilFil: Santana, Sandro IsaĂas. Universidade de Sao Paulo; BrasilFil: Silva, Pedro Henrique Felix. Universidade de Sao Paulo; BrasilFil: Messora, Michel R.. Universidade de Sao Paulo; Brasi
Neuromodulation and neuroprotective effects of chlorogenic acids in excitatory synapses of mouse hippocampal slices
The increased healthspan afforded by coffee intake provides novel opportunities to identify new therapeutic strategies. Caffeine has been proposed to afford benefits through adenosine A2A receptors, which can control synaptic dysfunction underlying some brain disease. However, decaffeinated coffee and other main components of coffee such as chlorogenic acids, also attenuate brain dysfunction, although it is unknown if they control synaptic function. We now used electrophysiological recordings in mouse hippocampal slices to test if realistic concentrations of chlorogenic acids directly affect synaptic transmission and plasticity. 3-(3,4-dihydroxycinnamoyl)quinic acid (CA, 1â10 ÎŒM) and 5-O-(trans-3,4-dihydroxycinnamoyl)-D-quinic acid (NCA, 1â10 ÎŒM) were devoid of effect on synaptic transmission, paired-pulse facilitation or long-term potentiation (LTP) and long-term depression (LTD) in Schaffer collaterals-CA1 pyramidal synapses. However, CA and NCA increased the recovery of synaptic transmission upon re-oxygenation following 7 min of oxygen/glucose deprivation, an in vitro ischemia model. Also, CA and NCA attenuated the shift of LTD into LTP observed in hippocampal slices from animals with hippocampal-dependent memory deterioration after exposure to ÎČ-amyloid 1â42 (2 nmol, icv), in the context of Alzheimerâs disease. These findings show that chlorogenic acids do not directly affect synaptic transmission and plasticity but can indirectly affect other cellular targets to correct synaptic dysfunction. Unraveling the molecular mechanisms of action of chlorogenic acids will allow the design of hitherto unrecognized novel neuroprotective strategies
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