A discrete particle model for reinforced concrete fracture analysis

Azevedo, N. Monteiro,Lemos, J.V.,Almeida, J.R. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.36 No.3

The Discrete Element Method adopting particles for the domain discretization has recently been adopted in fracture studies of non-homogeneous continuous media such as concrete and rock. A model is proposed in which the reinforcement is modelled by 1D rigid-spring discrete elements. The rigid bars interact with the rigid circular particles that simulate the concrete through contact interfaces. The DEM enhanced model with reinforcement capabilities is evaluated using three point bending and four point bending tests on reinforced concrete beams without stirrups. Under three point bending, the model is shown to reproduce the expected final crack pattern, the crack propagation and the load displacement diagram. Under four point bending, the model is shown to match the experimental ultimate load, the size effect and the crack propagation and localization.

Aggregate shape influence on the fracture behaviour of concrete

Azevedo, N.Monteiro,Lemos, J.V. Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.4

The Discrete Element Method, DEM, is increasingly used in fracture studies of non-homogeneous continuous media, such as rock and concrete. A 2D circular rigid DEM formulation, developed to model concrete, has been adopted. A procedure developed to generate aggregate particles with a given aspect ratio and shape is presented. The aggregate particles are modelled with macroparticles formed by a group of circular particles that behave as a rigid body. Uniaxial tensile and compression tests performed with circular and non-circular aggregates, with a given aspect ratio, have shown similar values of fracture toughness when adopting uniform strength and elastic properties for all the contacts. Non-circular aggregate assemblies are shown to have higher fracture toughness when different strength and elastic properties are set for the matrix and for the aggregate/matrix contacts.

A simple and effective method for addition silicone impression disinfection

Azevedo, Maria Joao,Correia, Ines,Portela, Ana,Sampaio-Maia, Benedita The Korean Academy of Prosthodonitics 2019 The Journal of Advanced Prosthodontics Vol.11 No.3

PURPOSE. Although dental impression disinfection is determinant to reduce the cross-infection risk, some studies have shown that, in real practice, the disinfection procedures vary considerably. Thus, the aim of this study was to evaluate the antimicrobial effectiveness and the impact on the dimensional stability of addition silicone' impressions of water wash and the most clinically used disinfection solutions: 3% hydrogen peroxide, commercial disinfectant MD520 (Durr) and 1% and 5.25% sodium hypochlorite. MATERIALS AND METHODS. For this investigation, dental impressions were taken on 16 volunteer dental students. The antimicrobial effectiveness of each procedure was evaluated by pour plate method. The dimensional stability was evaluated using a standardized stainless-steel model, according to ANSI/ADA nº19 specification. RESULTS. The study results showed that water wash does not alter the dimensional stability of addition silicone impressions but doesn't reduce the microbial load of the material (P>.05). On the other hand, addition silicone disinfection by immersion with 3% hydrogen peroxide, MD520 (Durr), or sodium hypochlorite at 1% and 5.25% does not alter the dimensional stability significantly but reduces > 99.9% of the microbial load of the impressions (P<.001). CONCLUSION. Addition silicone impressions should always be disinfected after water wash in order to reduce effectively the cross-infection risk. All disinfectants tested showed high antimicrobial efficiency without significant changes in three-dimensional shape of impressions. Hydrogen peroxide and sodium hypochlorite are of particular importance because are easily accessible in dental setting. The less explored hydrogen peroxide could be a valuable alternative for silicone impressions disinfection.

Lycopene and Tomato Sauce Improve Hepatic and Cardiac Cell Biomarkers in Rats

Vanessa Azevedo de Jesuz,Monique de Barros Elias Campos,Vanessa Rosse de Souza,Teresa Palmiciano Bede,Bianca Portugal Tavares de Moraes,Adriana Ribeiro Silva,Cassiano Felippe Gonc¸alves de Albuquerque 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.11

This study evaluated the effects of tomato sauce and lycopene on hepatic and cardiac cell biomarkers in rats fed a high-fat diet. Animals were split into five groups: control group, high-fat group (HG), high-fat tomato sauce group, high-fat lycopene 2 mg, and high-fat lycopene 4 mg. Food and water were offered ad libitum, whereas tomato sauce and lycopene (2 and 4 mg/day) were offered daily for 60 days. Body, heart, and liver weights, cardiosomatic and hepatosomatic indices, and serum parameters were also analyzed in rats. The animals' hearts and liver were processed, and cells were examined by flow cytometry. Results showed that the groups receiving tomato sauce and lycopene had lower glycemia. The serum concentration of high-density lipoprotein cholesterol, hepatic enzymes, and tumor necrosis factor-α did not change upon treatment. Tomato sauce and lycopene supplementation did not increase interleukin-1β in response to a high-fat diet. Cell cycle analysis of cardiac and liver cells showed a lower percentage of cells in the G0/G1 phase and an increase in the G2/M phase in HG. Both lycopene and tomato sauce reversed this effect. Both lycopene and tomato sauce reversed this effect and prevented high-fat diet-stimulated cardiac and liver cell death. Supplementation of tomato sauce and lycopene showed beneficial effects on cardiac and liver cell metabolism; therefore, it is suggested as a nutritional approach for the prevention and treatment of cardiovascular diseases and nonalcoholic hepatic steatosis.

More frequent detection of calcified carotid atherosclerotic plaques and mineralized laryngeal cartilages on digital than on film-based panoramic radiographs

de-Azevedo-Vaz, Sergio Lins,Machado, Joao Victor Pereira,Pereira, Teresa Cristina Rangel,Freitas, Deborah Queiroz Korean Academy of Oral and Maxillofacial Radiology 2019 Imaging Science in Dentistry Vol.49 No.1

Purpose: To determine whether calcified carotid atherosclerotic plaques(CCAPs) and mineralized laryngeal cartilages (MLCs) were more frequently detected on digital or film-based panoramic radiographs. The clinical relevance of this question is that some radiopacities seen on digital radiographs may correspond to medium-density tissues that are not necessarily mineralized. Materials and Methods: Data were collected from panoramic radiographs and the respective reports issued by 2 private oral radiology centers. A total of 388 radiographs and reports were divided into film-based (group A) and digital (group D) radiographs. The frequencies of CCAPs and MLCs were analyzed using the Fisher exact test, and odds ratios were also calculated (${\alpha}=1%$). Results: The mean age of patients whose reports and radiographs showed CCAPs and/or MLCs ranged from 50.1 to 54.1 years. There was a predominance of females. A higher frequency of CCAPs and MLCs was observed in group D than in group A at both centers(P<0.01). CCAPs and MLCs were detected 4 times more frequently in group D than in group A at one of the centers. Conclusion: CCAPs and MLCs were more frequently detected on digital than on film-based panoramic radiographs. Further studies are needed to determine whether such radiopacities do indeed correspond to mineralized, rather than medium-density, tissues.

In Vivo Antimutagenic Properties of Transgenic and Conventional Soybeans

Luciana Azevedo,Nathalia R.V. Dragano,Ana P.L. Sabino,Maria Christina C. Resck,Patricia L. Alves de Lima,Cibele M.C.P. Gouvea 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.6

The goal of the this study was to evaluate the mutagenic/antimutagenic effects of conventional (BRS133) and transgenic (BRS 245 RR) soybeans (CS and TS, respectively) in vivo using the bone marrow micronucleus (MN) test, histopathological analysis, chromosome aberration test (CAT), and mitotic index (MI) determination. Six-week-old male Swiss mice were fed with pelleted commercial diet mixed with CS or TS at 10% or 20%. Two experimental designs (MN and CAT) were conducted simultaneously with 10 groups each during a 15-day period. Animals were treated with pelleted commercial diet, CS (10% or 20%), or TS (10% or 20%), and on day 14 they also received cyclophosphamide (CP) (50mg/kg i.p.). The 10% and 20% CS and TS diets did not significantly decrease the frequencies of micronucleated polychromatic erythrocytes in bone marrow induced by CP. However, the CAT indicated that the 10% and 20% CS diets significantly (P<.05) protected nucleated bone marrow cells against chemical-induced mutagenesis and also produced a significant (P<.05) decrease in the total percentage of spontaneous aberrations. Among the treatments with TS, only the 10% TS diet reduced the percentage of total aberrations induced by CP. The results also indicated that the treatment with 20% TS alone significantly (P<.05) decreased the MI, indicating cytotoxic effects related to the treatment. Taken together, our results suggest that, under the tested conditions, TS and CS have antimutagenic properties and are not toxic.

Screening of Yeasts Isolated from Brazilian Environments for the 2-Phenylethanol (2-PE) Production

Lorena Azevedo de Lima,Raphael Hermano Santos Diniz,Marisa Vieira de Queiroz,Luciano Gomes Fietto,Wendel Batista da Silveira 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.3

Phenylethanol alcohol, or 2-phenylethanol (2-PE) production by yeasts has been considered a promising alternative to its chemical synthesis. In order to evaluate the potential of yeast strains isolated from different Brazilian environments, we evaluated the 2-PE production of 267 strains. Among them, the Kluyveromyces marxianus CCT 7735 yeast stood out as being the best 2-PE producer. The K. marxianus CCT 7735 growth was impaired by 2-PE; nevertheless, this effect is less pronounced than the inhibition reported for certain Saccharomyces cerevisiae strains. The maximum 2-PE titer obtained under optimized conditions was 3.44 g/L, 28% higher than the titer achieved under unoptimized conditions. The optimized conditions were: 30ºC, and glucose and L-phe concentrations of 3.0 and 4.0 g/L, respectively. Moreover, the specific production rate of 2-PE increased twofold compared to the unoptimized conditions.

EFFECTS OF ALKALINITY ON JUVENILE COBIA Rachycentron canadum REARED IN LOW SALINITY

Bianca Azevedo Lopez,Ricardo Vieira Rodrigues,Marcelo Borges Tesser,Luis Andre Sampaio 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5

OsDof25 expression alters carbon and nitrogen metabolism in Arabidopsis under high N-supply

Leandro Azevedo Santos,Sonia Regina de Souza,Manlio Silvestre Fernandes 한국식물생명공학회 2012 Plant biotechnology reports Vol.6 No.4

To verify the effect of the transcription factor OsDof25 on the nitrogen metabolism in plants, it was cloned for expression in Arabidopsis thaliana under the control of the 35S promoter. Lineages with different expression levels of this gene were obtained, and when grown in a half-strength MS medium (10 mM of NH4? and 20 mM of NO3-) showed phenotypes with visible chloroses and growth disorders. It was observed that OsDof25increased the levels of expression of high and low affinity ammonium transporters (AtAMT1.1 and AtAMT2.1,respectively) and repressed the high affinity nitrate transporter (AtNRT2.1). We also verified an increase in total amino-N content and expressions of the pyruvate kinase (PK1 and PK2), phosphoenolpyruvate carboxylase (PEPC1and PEPC2) and NADP-dependent and NAD-dependent isocitrate dehydrogenase. In addition, an increase in expression levels and activity of glutamate dehydrogenase was also observed. The simultaneous increase in the expression of AMTs and enzymes of carbon metabolism may explain the high levels of amino-N found in the transgenic plants. The data found in this work suggest that OsDof25 expression simultaneously affects NH4? uptake and organic acid metabolism in plants.

Clinical and Echocardiographic Characterization of False-Positive Results from Stress Echocardiography

Rui Azevedo Guerreiro,Paula Fazendas,Ana Rita Pereira,Ana Marques,João Pais,Sofia Alegria,Kisa Hyde Congo,Ana Catarina Gomes,João Carvalho,Gonçalo Morgado,Inês Cruz,Ana Rita Almeida,Isabel João,Hélder 한국심초음파학회 2020 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.28 No.2

BACKGROUND: Stress echocardiography has a 72%–85% sensitivity and an 80%–95% specificity. In this study, we characterized patients who received a false-positive stress echocardiogram result. METHODS: A total of 5,256 patients underwent a stress echocardiogram (induced by exercise, dobutamine, or dipyridamole) between 2009 to 2018, and 405 patients (7.7%) received a positive result. Among the positive patients, 300 underwent coronary angiography within 12 months, and these patients were included in this study (mean age = 64.9 ± 9.4 years, 230 men [76.7%]). Coronary artery disease was diagnosed by stenosis ≥50% in any epicardial coronary artery. Clinical and echocardiographic variables were compared between patients with true- and false-positive stress echocardiogram results. RESULTS: Seventy-two patients (24%) had a false-positive stress echocardiogram, with similar rates across stressor types (p = 0.574). Patients with false positives were less frequently men (63.9% vs. 80.7%, p = 0.003), had lower diabetes mellitus prevalence (15.3% vs. 45.6%, p = 0.001), were similar to true positive patients with regard to body-mass index, arterial hypertension prevalence, hyperlipidemia and smoking, and had lower pre-test probability of coronary artery disease (23% vs. 32%, p = 0.016). The wall motion score index (WMSI) was higher in the true-positive stress group, and wall motion abnormalities were more frequent in the apical segments (70.5% vs. 56.7%, p = 0.034). In a multivariable predictive model, men (odds ratio [OR] = 2.994), diabetes (OR = 5.440), and peak WMSI (OR = 10.690) were associated with a true-positive result. CONCLUSIONS: Twenty-four percent of our study population received a false-positive stress echocardiogram result, with similar rates across stressor types. Patients with true-positive stress echocardiogram results are more likely to be men, diabetic, and have a high peak WMSI.