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A new formulation of cracking in concrete structures based on lumped damage mechanics
Daniel V.C. Teles,Rafael N. Cunha,Ricardo A. Picón,David L.N.F. Amorim,Yongtao Bai,Sergio P.B. Proença,Julio Flórez-López 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.5
Lumped Damage Mechanics (LDM) is a theory proposed in the late eighties, which assumes that structural collapse may be analyzed as a two-phase phenomenon. In the first (pre-localization) stage, energy dissipation is a continuous process and it may be modelled by means of the classic versions of the theory of plasticity or Continuum Damage Mechanics (CDM). The second, post-localization, phase can be modelled assuming that energy dissipation is lumped in zones of zero volume: inelastic hinges, hinge lines or localization surfaces. This paper proposes a new LDM formulation for cracking in concrete structures in tension. It also describes its numerical implementation in conventional finite element programs. The results of three numerical simulations of experimental tests reported in the literature are presented. They correspond to plain and fiber-reinforced concrete specimens. A fourth simulation describes also the experimental results of a new test using the digital image correlation technique. These numerical simulations are also compared with the ones obtained using conventional Cohesive Fracture Mechanics (CFM). It is then shown that LDM conserves the advantages of both, CDM and CFM, while overcoming their drawbacks.
V. A. CUNHA,X. L. TRAVASSOS 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.4
To increase car passenger safety, the Brazilian National Traffic Council (CONTRAN) released Resolution 221,which defines the maximum passenger and driver biomechanical criteria in the event of a vehicle frontal impact. The vehicle maximum allowed biomechanical injury criteria will be enforced from January 2012 for new vehicles and in January 2014 for vehicles in production before January 2014. To standardize the test method to measure the driver and front passenger injury values in a frontal crash, Resolution 221 states that the tests must be performed according to the ABNT NBR 15300-1standard, followed by the ABNT NBR 15300-2 standard or the ABNT NBR 15300-3 standard. The use of ABNT NBR 15300-2 or ABNT NBR 15300-3 standards is a free choice for the manufacturer of the vehicle. The ABNT NBR 15300-1 +15300-2 test is similar to the FMVSS 208 standard in the United States in terms of its vehicle frontal impact test perpendicular to a rigid barrier with the use of seat belts by male model dummies. The test according to ABNT NBR 15300-1 + 15300-3follows the European ECE R94 and 96/79/EC standards. However, ABNT NBR 15300-2 focuses on occupant protection during vehicle deceleration rather than occupant protection during vehicle deformation in a crash test. ABNT NBR 15300-3tests occupant protection during vehicle deformation more than it tests occupant protection during vehicle deceleration. Therefore, this paper aims to show the types of test results produced by the ABNT NBR 15300-2 and ABNT NBR 15300-3standards and their differences concerning occupant protection verification and discuss the manufacturer’s freedom of choice.
Francisco A.B. Cunha,Edinardo F.F. Matias,Samuel V. Brito,Felipe S. Ferreira,João Marcelo A. Braga,José G.M. Costa,Henrique D.M. Coutinho 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.9
In this study, ethanol extracts of stems and leaves of Costus cf. arabicus L. were evaluated for antibacterial activity against multidrug-resistant strains of Escherichia coli and Staphylococcus aureus. The antibacterial and modulatory activities of the extracts were assayed by microdilution. The light-enhanced antibacterial activity was assayed by a light regimen. The growth of the bacteria tested was not inhibited by the extracts. The minimum inhibitory concentration values were ≥1,024 μg/mL. However, the antibiotic activity of aminoglycosides was synergistically enhanced when these extracts at subinhibitory concentrations were combined with the antibiotics. Also, both extracts showed activity against the wild-type bacterial strains, but the leaf extract was the more active extract, being active against both S. aureus and E. coli. Therefore, we conclude that the ethanol extracts of stems and leaves of C. cf. arabicus L. have potential light-induced antibacterial activity and synergistic antibiotic activity. This study showed that these extracts may be a promising source of antibacterial and modulatory agents.
Natural Products from Garcinia brasiliensis as Leishmania Protease Inhibitors
Ivan O. Pereira,Diego M. Assis,Maria A. Juliano,Rodrigo L.O.R. Cunha,Clara L. Barbieri,Luis V.S. do Sacramento,Marcos J. Marques,Marcelo H. dos Santos 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.6
The infections by protozoans of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which cause renal and cardiac toxicity. As part of a search for new drugs against leishmaniasis, we evaluated the in vitro Leishmania protease inhibition activity of extracts (hexanic, ethyl-acetate, and ethanolic) and fukugetin, a bioflavonoid purified from the ethyl-acetate extract of the pericarp of the fruit of Garcinia brasiliensis, a tree native to Brazilian forests. The isolated compound was characterized by using spectral analyses with nuclear magnetic resonance, mass spectroscopy, ultraviolet, and infrared techniques. The ethyl-acetate extract and the compound fukugetin showed significant activity as inhibitors of Leishmania's proteases, with mean (±SD) IC50 (50% inhibition concentration of protease activity) values of 15.0±1.3 μg/mL and 3.2±0.5 μM/mL, respectively, characterizing a bioguided assay. In addition, this isolated compound showed no activity against promastigote and amastigote forms of L. (L.) amazonensis and mammalian cells. These results suggest that fukugetin is a potent protease inhibitor of L. (L.) amazonensis and does not cause toxicity in mammalian or Leishmania cells in vitro. This study provides new perspectives on the development of novel drugs that have leishmanicidal activity obtained from natural products and that target the parasite's proteases.
( Bruno P. Carvalho ),( Andrielle T. M. Cunha ),( Bianca D. M. Silva ),( Regivaldo V. Sousa ),( Ligiane O. Leme ),( Margot A. N. Dode ),( Eduardo O. Melo ) 한국축산학회(구 한국동물자원과학회) 2019 한국축산학회지 Vol.61 No.2
The hG-CSF (human Granulocyte Colony-Stimulating Factor) is a growth and stimulation factor capable of inducing the proliferation of bone marrow cells, several types of leukocytes, among other hematopoietic tissue cells. hG-CSF is used in used to treat anomalies that reder a small number of circulating white blood cells, which may compromise the immune defenses of the affected person. For these reasons, the production of hG-CSF in a bioreactor system using the mammary gland of genetic modified animals is a possibility of adding value to the bovine genetic material and reducing the costs of hG-CSF production in pharmaceutical industry. In this study, we aimed the production of transgenic hG-CSF bovine through the lipofection of bovine primary fibroblasts with an hG-CSF expression cassette and cloning these fibroblasts by the somatic cell nuclear transfer (SCNT) technique. The bovine fibroblasts transfected with the hG-CSF cassette presented a stable insertion of this construct into their genome and were efficiently synchronized to G0/G1 cell cycle stage. The transgenic fibroblasts were cloned by SCNT and produced 103 transferred embryos and 2 pregnancies, one of which reached 7 months of gestation.
In vitro and in vivo effects of Melaleuca alternifolia nanoparticles in Meloidogyne sp.
Madalosso R.G.,Verdi C.M,Souza M.E,Cunha J.A.,Santos P.S.,Balardin R.S,Madalosso M.G.,Santos R.C.V 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.4
Soybeans in Brazil stand out as the major grain grown throughout the country, being economically and socially essential. However, there are several limiting factors for its production such as diseases caused by nematodes, mainly the species of the genus Meloidogyne sp. that prevent the production in infested areas. In order to find new alternatives for the protection and control of such disease, the following study aimed to determine the nematicidal activity of Melaleuca alternifolia oil in its pure form and solid lipid nanocarriers containing the oil. It was found that both the pure essential oil and its nanostructured form presented nematicidal potential in vitro and in vivo, however, at different times of action. All concentrations were active and similar regarding action to abamectin, the conventional treatment. In this sense, this paper for the first time presents the action of M. alternifolia nanoparticles in the treatment/prevention of infections by Melodogyne sp.