Search

Adhesives offer significant advantages when joining materials since they do not create discontinuities in the material, unlike bolting or riveting. Another interest of adhesive joints is the possibility of joining different materials and the lower weight. The analysis of the stress singularity in adhesive joints can provide a better understanding of joint behaviour, and it is mesh independent. The ISSF is based on a fracture mechanics concept, the Stress Intensity Factor (SIF). However, generally, the SIF is only applicable to cracks in a single material, while the ISSF is applicable to multi-material corners and does not require a crack. This work aims to study the stress singularity of aluminium adhesive joints bonded with a brittle adhesive with four different overlap lengths (LO) by determining the singularity's exponents and its intensity. A method for joint strength prediction using the ISSF is also proposed. Additionally, the interface corner's stress is studied, with the different singularity components presented separately to assess their influence on the overall stress. These predictions are also compared with the experimental strength to verify this strength prediction criterion's accuracy when applied to brittle adhesives. In conclusion, the ISSF criterion provides accurate results and can be utilised for further studies in this area. [ABSTRACT FROM AUTHOR]

Aims: To study the expression of p63, cytokeratin (CK) 5 and CK8/18 in invasive ductal carcinomas and their relationship with BRCA1 and other pathological and immunohistochemical features of clinical significance. Methods and results: Immunohistochemistry with the antibodies p63, CK5, CK8/18, BRCA1, oestrogen receptor, progesterone receptor, p53, c-erbB-2 and Ki67 was performed in 102 formalin-fixed paraffin-embedded samples of invasive ductal carcinomas. The CK5+ cases were submitted to a double-immunolabelling study with p63. There was a strong relationship between CK5 and p63 expression and both markers were associated with hormonal receptor-negative high-grade carcinomas with high proliferative rate. Furthermore, there was coexpression of CK5 and p63 in neoplastic cells, indicating that p63, like CK5, is a marker of the basal phenotype of breast cancer. There was a strong relationship between reduced expression of BRCA1 with both p63 and CK5 expression as well as an inverse correlation between p63 and CK8/18 expression, suggesting that loss of p63 expression is required for the transition between a basal to a luminal phenotype of breast carcinoma. Conclusions: Since p63 is thought to be a marker of stem cells and may act as an oncogene, our data support the idea that BRCA1 acts as stem cell regulator. [ABSTRACT FROM AUTHOR]

Various configurations of adhesive joints exist, each with unique characteristics. In the case of peel load solicitations, T-joints are the most common choice but are not sufficiently addressed in the literature, especially regarding the geometrical and material influence on their performance. Recently, meshless methods, like the Radial Point Interpolation Method (RPIM), have been used as alternatives to the Finite Element Method (FEM) for investigating joint behaviours. The present work aims to study the free length (FL) effect in T-joints, which is related to substrate stiffness. Three distinct FL dimensions were evaluated. At the same time, the effect of tp2 and adhesive type were taken into account. Initially, joint strength (Pmax) was predicted using two numerical approaches: FEM and RPIM, both employing elastic-plastic material models. Subsequently, the results were compared with the experimental data. Moreover, two yield criteria were considered to analyse the adhesive: von Mises and the Exponential Drucker-Prager criteria. The data resultant from this first phase was then used to select the correct yield criterion for evaluating the influence of FL in the adhesive joints. The methodology was validated, and then geometrical and material design recommendations were presented for the efficient use of T-joints in structural applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of oral creatine supplementation on the athletic performance of equines used for barrel racing. Ten healthy Quarter Horses, or Quarter Horse crossbred, weighing 429.7 ± 25.3 kg and with mean age of 3.8 ± 1.2 years, were used. Animals were evaluated in four different moments (M1, M2, M3, M4), and between M3 and M4, they were supplemented with 28 g of creatine/100 kg of body weight, orally, for 45 days. Although significant alterations for LDH activity, plasma glucose and packed cell volume were observed, it was possible to conclude that there was no improvement in the athletic performance for the animals used on the experiment, as there were no changes in time scores, heart rate and plasma lactate, variables considered as performance indicators, before and after supplementation. [ABSTRACT FROM AUTHOR]

Nowadays, the adhesive bonding method has a very strong presence in the most varied industries, especially in aeronautics, which strongly boosted the use of adhesively bonded joints. Curved bonded joints are commonly used in the aeronautical industry, where curved panels typically made of carbon fibre-reinforced polymer (CFRP) are joined to fabricate several fuselage parts. This work compares the performance of three adhesives (brittle, moderately ductile and ductile) in curved single-lap joints (SLJ) bonded with CFRP adherends, considering the modifications of the following geometric parameters: overlap length (LO), adherend thickness (tP) and adherends' radius of curvature (R). For the analysis of these joints, the finite element method (FEM) was used with cohesive zone model (CZM), and the discussions of joint behaviour included the internal stresses of the adhesive, joint strength and energy dissipated at failure (U). Before the numerical analysis, validation with experiments was carried out considering flat SLJ, with positive results. The numerical study on the curved SLJ showed a significant maximum load (Pm) and U improvement by increasing LO for the two ductile adhesives. For the same adhesives, bigger tP reduced Pm. On the other hand, the brittle adhesive revealed to be only minor affected by these parameter variations. Thus, with this work, clear design guidelines are proposed for curved SLJ. [ABSTRACT FROM AUTHOR]

Background: Non-alcoholic steatohepatitis (NASH) is highly associated with metabolic syndrome, a major cause of morbidity in the globalized society. The renin-angiotensin system (RAS) influences hepatic fatty acid metabolism, inflammation and fibrosis. Thus, in the present study, we aimed to evaluate the effect of aliskiren, a direct renin inhibitor, on metabolic syndrome-related NASH. Methods: C57BL/6 male mice (n = 45) were divided into three groups: controls; animals inoculated with streptozotocin (STZ) (40 mg/kg/day) for 5 days and fed with high fat diet (HFD) for 8 weeks; and animals inoculated with STZ for 5 days, fed with HFD for 8 weeks and treated with aliskiren (100 mg/kg/day) for the final 2 weeks. Glycemic and insulin levels, hepatic lipid profile, histological parameters and inflammatory protein expression were analyzed. Results: Aliskiren normalized plasma glucose and insulin levels, reduced cholesterol, triglycerides and total fat accumulation in liver and diminished hepatic injury, steatosis and fibrosis. These results could be explained by the ability of aliskiren to block angiotensin-II, lowering oxidative stress and inflammation in liver. Also, it exhibited a beneficial effect in increasing insulin sensitivity. Conclusion: These findings support the use of aliskiren in the treatment of metabolic syndrome underlying conditions. However, clinical studies are indispensable to test its effectiveness in the treatment of patients with metabolic syndrome. [ABSTRACT FROM AUTHOR]

Background A probiotic formulation ( Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 combination, Probio'Stick®) displays anxiolytic-like activity and reduces apoptosis in the lymbic system in animal models of depression. Based on the hypothesis that modulation of gut microbiota by this probiotic formulation has beneficial effects on brain activity in stress conditions, we report a set of probiotic-evoked physiological, cellular, and molecular events in the brain of Probio'Stick® pretreated mice submitted to chronic psychological stress. Methods Water avoidance stress ( WAS) was applied or not (sham). Hypothalamic-pituitary-adrenal ( HPA) axis and autonomic nervous system ( ANS) responses to the chronic stress were assessed through plasma corticosterone and catecholamine measurements. Specific markers for neuronal activity, neurogenesis, and synaptic plasticity were used to assess brain activity. In addition, gut permeability and tight junction ( TJ) proteins levels were also determinated. Key Results We observed that a pretreatment with the probiotic formulation attenuated HPA axis and ANS activities in response to WAS, and reduced cFos expression in different brain areas but Lactobacillus salivarius (a negative control) treatment was ineffective on these parameters. Moreover, probiotic pretreatment prevented the WAS-induced decrease hippocampal neurogenesis and expression changes in hypothalamic genes involved in synaptic plasticity. These central effects were associated with restoration of TJ barrier integrity in stressed mice. Conclusions & Inferences These data suggest that chronic stress-induced abnormal brain plasticity and reduction in neurogenesis can be prevented by a pretreatment with the Probio'Stick® formulation, suggesting that probiotics modulate neuroregulatory factors and various signaling pathways in the central nervous system involved in stress response. [ABSTRACT FROM AUTHOR]