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Search Results: 1 - 10 of 281777 matches for " F. K.;Teixeira Neto "
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Alumina ceramics obtained by chemical synthesis using conventional and microwave sintering
Thomazini, D.;Gelfuso, M. V.;Chinelatto, A. S. A.;Chinelatto, A. L.;Sanson, F. K.;Teixeira Neto, F.;
Ceramica , 2011, DOI: 10.1590/S0366-69132011000100006
Abstract: it is well known that the heating mechanism and powder precursor define the microstructural characteristics of ceramics. especially abnormal grain growth of pure alumina ceramics developed during conventional sintering method suggests that this material is a potential candidate to be treated in microwave sintering process. alumina ceramics produced with commercial (a1k) and chemically synthesized powders were sintered in conventional and microwave furnaces. two methods were employed to prepare the chemically synthesized nanosized powders: pechini method and emulsification with oleic acid. the microwave sintered samples were characterized by apparent density and scanning electron microscopy and compared with the samples sintered in a conventional furnace. alumina ceramics sintered in the microwave furnace had fine grained microstructure, not related with the starting powders. this characteristic was achieved in a sintering time shorter than those produced in the conventional furnace. however, satisfactory densification was observed only to a1k ceramics (3.95 g/cm3) sintered during one hour in microwave furnace.
Late Results of Endoventricular Patch Plasty Repair in Akinetic and Dyskinetic Areas After Acute Myocardial Infarction
Prates, Paulo R.;Homsi Neto, Abud;Lovato, Lucas Maynard;Teixeira Fo, Guaracy F.;Sant'Anna, Jo?o R. M.;Yordi, Luiz M.;Kalil, Renato A. K.;Nesralla, Ivo A.;
Arquivos Brasileiros de Cardiologia , 2002, DOI: 10.1590/S0066-782X2002001100002
Abstract: objective - to assess the surgical results of endoventricular patch plasty repair in akinetic and dyskinetic left ventricular areas. methods - we studied 52 patients who had undergone endoventricular patch plasty repair associated with myocardial revascularization. the preoperative functional class distribution was as follows: class i in 1 (1.9%) patient; class ii in 2 (3.8%) patients; class iii in 23 (44.2%) patients; and class iv in 26 (50%) patients. results - the immediate mortality rate was 7.6% (4 patients). the clinical outcome of 44 patients followed up within a mean postoperative time of 29±25 months was as follows: class i in 33 (75%) patients; class ii in 7 (15.9%) patients; class iii in 2 (4.5%) patients; and class iv in 2 (4.5%) patients. comparison between pre- and postoperative catheterization in 21 patients showed that the ejection fraction increased from 46.3% to 51.3% (p=0. 17); the left ventricular systolic volume decreased from 76.4 ml to 57.5 ml, (p=0.078); and the left ventricular diastolic volume decreased from 141.2 ml to 105.8 ml (p=0.0 73). these findings showed the tendency toward improvement, but with nonsignificant results. conclusion - the technique proved to be effective, to have a low mortality rate, to cause significant clinical improvement, an increase in ejection fraction, and a reduction in left ventricular volumes.
Sinteriza??o de ceramicas à base de PZT em forno de microondas
Gelfuso, M. V.;Teixeira Neto, F.;Thomazini, D.;
Ceramica , 2007, DOI: 10.1590/S0366-69132007000300015
Abstract: ferroelectric ceramics based on lead zirconate titanate doped with neodymium were sintered using a modified microwave oven. in this process the energy is transferred directly to the material through the interaction between molecules of the material with the electromagnetic field. the microwave sintering process has an advantage to reduce the time and save energy. this type of process involves energy conversion, opposing to heat transfer. ceramic parts were produced by thermal treatments at 1100 oc and 1200 oc up to 30 min. the formed crystalline phases were investigated by x-ray diffraction. ceramic parts with densities above 95% of the theoretical density were produced in 10 min by heating at 1100 oc, with heating rate of 400 oc/min. values of dielectric constant and loss factor of ceramics with density above 90%t.d. were determined.
Laparoscopic colorectal surgery: what to expect from an initial experience
Teixeira, Fábio Ramos;Teixeira, Gustavo Ramos;Santos, Thiago Costa dos;Torres Neto, Juvenal da Rocha;
Journal of Coloproctology (Rio de Janeiro) , 2012, DOI: 10.1590/S2237-93632012000200011
Abstract: laparoscopic colorectal surgery is less traumatic when compared to traditional surgery techniques, with well-established advantages. the objective of this study was to report the experience in laparoscopic surgical treatment of colorectal diseases. method: catalog all patients submitted to laparoscopic colorectal surgery performed by one surgeon and perform a descriptive analysis of key data from these records. results: the study analyzed data from 43 patients who underwent laparoscopic colorectal surgery. most were females (n=30; 69.77%) in relation to males (n=13; 30.23%), mean age of 57.21 years old. among the indications for surgery, diverticular disease was the most frequent (n=20; 46.51%), followed by malignancy (n=13; 30.23%). most patients underwent rectosigmoidectomy (n=28; 65.12%), followed by right hemicolectomy (n=6; 13.95%), with conversions in five cases (11.63%). the study observed a tendency towards increased number of surgeries, reduced average operative time as well as decreased conversions to laparotomy along the studied period. conclusion: laparoscopic colorectal surgery is a safe procedure, and with the technical development of the team, the results have been increasingly good.
Robust Computation of Dipole Electromagnetic Fields in Arbitrarily-Anisotropic, Planar-Stratified Environments
K. Sainath,F. L. Teixeira,B. Donderici
Physics , 2013, DOI: 10.1103/PhysRevE.89.013312
Abstract: We develop a general-purpose formulation, based on two-dimensional spectral integrals, for computing electromagnetic fields produced by arbitrarily-oriented dipoles in planar-stratified environments, where each layer may exhibit arbitrary and independent anisotropy in both the (complex) permittivity and permeability. Among the salient features of our formulation are (1) computation of eigenmodes (characteristic plane waves) supported in arbitrarily anisotropic media in a numerically robust fashion, (2) implementation of an hp-adaptive refinement for the numerical integration to evaluate the radiation and weakly-evanescent spectra contributions, and (3) development of an adaptive extension of an integral convergence acceleration technique to compute the strongly-evanescent spectrum contribution. While other semianalytic techniques exist to solve this problem, none have full applicability to media exhibiting arbitrary double anisotropies in each layer, where one must account for the whole range of possible phenomena such as mode coupling at interfaces and non-reciprocal mode propagation. Brute-force numerical methods can tackle this problem but only at a much higher computational cost. The present formulation provides an efficient and robust technique for field computation in arbitrary planar-stratified environments. We demonstrate the formulation for a number of problems related to geophysical exploration.
Topology and Fragility in Cosmology
M. J. Reboucas,R. K. Tavakol,A. F. F. Teixeira
Physics , 1997, DOI: 10.1023/A:1018809922606
Abstract: We introduce the notion of topological fragility and briefly discuss some examples from the literature. An important example of this type of fragility is the way globally anisotropic Bianchi V generalisations of the FLRW $k=-1$ model result in a radical restriction on the allowed topology of spatial sections, thereby excluding compact cosmological models with negatively curved three-sections with anisotropy. An outcome of this is to exclude chaotic mixing in such models, which may be relevant, given the many recent attempts at employing compact FLRW $k=-1$ models to produce chaotic mixing in the cosmic microwave background radiation, if the Universe turns out to be globally anisotropic.
Efeitos de diferentes substratos e da profundidade de semeadura na germina??o de sementes de mata-pasto e malva
Souza Filho, Antonio P. S.;Dutra, Saturnino;Silva, Maria A. M. M.;Teixeira Neto, José F.;
Planta Daninha , 1998, DOI: 10.1590/S0100-83581998000100007
Abstract: the flotations in the germination of seeds in the field are governed by a group of environmental factors. in the present work it was analysed the effects of the ph, salinity and aluminium on the germination of seeds, and of the sowing depth on the rate of seedling emergency of the pasture weeds cassia tora and urena lobata. all studies were carried out in laboratory, excpet those of sowing depht which were accomplished at a greenhouse. the germination and the seedling emergency rate were monitored in period of 15 and 20 days, respectively. the results showed that the ph in the band from 3 to 11 and the concentration of aluminium of 0 to 2,0 meq/100 ml, did not affect seed germination of the two weeds cassia tora and urena lobata answered similarly to salinity until the level of 150 mm. however, for the concentration of 300 mm urena lobata was more tolerant to salinity than the cassia tora, whose seeds did not germinate in this salt concentration. the relationship between seedling emergency rate and sowing depth was quadratic for both species. cassia tora, however, showed larger capacity to emerge than the urena lobata at the depth of 8 cm, this later species presenting a rate of emergency zero when sowed in this depth.
Aspectos epidemiológicos dos pólipos e les?es plano-elevadas colorretais
Torres Neto, Juvenal da Rocha;Arcieri, Jofrancis Santos;Teixeira, Fábio Ramos;
Revista Brasileira de Coloproctologia , 2010, DOI: 10.1590/S0101-98802010000400006
Abstract: introduction: colorectal polyps and flat injuries are important for the prevention of colorectal cancer due to the malignancy of adenomas. objective: to describe the demographic profile of patients with endoscopic diagnosis of colorectal polyps and/or flat injuries at university hospital of universidade federal de sergipe and torres medical center. methods: a total of 6,919 records were evaluated from january 2002 to december 2007 with respect to the following variables: age, gender, origin, indication; injury evaluation os number, size, morphology, histology, dysplasia degree, topography; synchronics and metachronics injuries and associated diagnoses. results: 1,031(13.51%) colorectal polyps and flat injuries were found in 935 tests, accounting for 826 patients, 46% males and 54% females. the age ranged from 3 to 96 years with average of 53.64. the most frequent topographic distribution of polypoid injuries were rectum and sigmoid (58.40%). the injuries were sessile in 52.80% of the cases, pedicle in 27.90%, and flat injuries in 19.30%. there were synchronical injuries in 23.48% of patients and metachronic in 22 patients. histologically, 43.36% were adenomas, being 85.70% tubular, 9.60% tubulovillous and 4.70% villous; hyperplastic polyps were found in 30.64% of the cases, inflammatory in 15.80% and 10.20% presented other histological types. the adenomas showed low-grade dysplasia in 83.40% and high degree in 16.60% of the patients. seven were adenoma-carcinomas, one was carcinoid and one was gastrointestinal stromal tumor. conclusions: the colonoscopy and polypectomy are important in diagnosis and prevention of colorectal cancer.
Late Results of Endoventricular Patch Plasty Repair in Akinetic and Dyskinetic Areas After Acute Myocardial Infarction
Prates Paulo R.,Homsi Neto Abud,Lovato Lucas Maynard,Teixeira Fo Guaracy F.
Arquivos Brasileiros de Cardiologia , 2002,
Abstract: OBJECTIVE - To assess the surgical results of endoventricular patch plasty repair in akinetic and dyskinetic left ventricular areas. METHODS - We studied 52 patients who had undergone endoventricular patch plasty repair associated with myocardial revascularization. The preoperative functional class distribution was as follows: class I in 1 (1.9%) patient; class II in 2 (3.8%) patients; class III in 23 (44.2%) patients; and class IV in 26 (50%) patients. RESULTS - The immediate mortality rate was 7.6% (4 patients). The clinical outcome of 44 patients followed up within a mean postoperative time of 29±25 months was as follows: class I in 33 (75%) patients; class II in 7 (15.9%) patients; class III in 2 (4.5%) patients; and class IV in 2 (4.5%) patients. Comparison between pre- and postoperative catheterization in 21 patients showed that the ejection fraction increased from 46.3% to 51.3% (p=0. 17); the left ventricular systolic volume decreased from 76.4 mL to 57.5 mL, (p=0.078); and the left ventricular diastolic volume decreased from 141.2 mL to 105.8 mL (p=0.0 73). These findings showed the tendency toward improvement, but with nonsignificant results. CONCLUSION - The technique proved to be effective, to have a low mortality rate, to cause significant clinical improvement, an increase in ejection fraction, and a reduction in left ventricular volumes.
The Teleparallel Lagrangian and Hamilton-Jacobi Formalism
B. M. Pimentel,P. J. Pompeia,J. F. da Rocha-Neto,R. G. Teixeira
Physics , 2003, DOI: 10.1023/A:1022951321978
Abstract: We analyze the Teleparallel Equivalent of General Relativity (TEGR) from the point of view of Hamilton-Jacobi approach for singular systems
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