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Search Results: 1 - 10 of 813703 matches for " M. A. L.;Milanez "
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Hydrogen from biomass gas steam reforming for low temperature fuel cell: energy and exergy analysis
Sordi, A.;Silva, E. P.;Milanez, L. F.;Lobkov, D. D.;Souza, S. N. M.;
Brazilian Journal of Chemical Engineering , 2009, DOI: 10.1590/S0104-66322009000100015
Abstract: this work presents a method to analyze hydrogen production by biomass gasification, as well as electric power generation in small scale fuel cells. the proposed methodology is the thermodynamic modeling of a reaction system for the conversion of methane and carbon monoxide (steam reforming), as well as the energy balance of gaseous flow purification in psa (pressure swing adsorption) is used with eight types of gasification gases in this study. the electric power is generated by electrochemical hydrogen conversion in fuel cell type pemfc (proton exchange membrane fuel cell). energy and exergy analyses are applied to evaluate the performance of the system model. the simulation demonstrates that hydrogen production varies with the operation temperature of the reforming reactor and with the composition of the gas mixture. the maximum h2 mole fraction (0.6-0.64 mol.mol-1) and exergetic efficiency of 91- 92.5% for the reforming reactor are achieved when gas mixtures of higher quality such as: ggas2, ggas4 and ggas5 are used. the use of those gas mixtures for electric power generation results in lower irreversibility and higher exergetic efficiency of 30-30.5%.
Cimento aluminoso e seus efeitos em concretos refratários magnesianos espinelizados in situ
Milanez, D. H;Sako, E. Y;Maia, M. F;Braulio, M. A. L;Bittencourt, L. R. M;Pandolfelli, V. C;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000100015
Abstract: calcium aluminate cement (cac) bonded alumina-magnesia refractory castables present great advantages for steel ladle applications as a result of in-situ expansive formation of spinel and ca<6, which leads to high basic slag and thermal shock resistance. the cac content in those castables strongly influences its expansive behavior mainly due to ca6 formation. in the present work, the effects of the cac content in magnesia-alumina castables were analyzed. the results showed that calcium aluminate cement affects the volumetric stability of mgo-spinel system: the lower the cac content, the lower the shrinkage. these effects on the sintering and in the mechanical properties after sintering at high temperatures are also presented and discussed.
Forma??o in-situ ou adi??o de espinélio pré-formado: o que é melhor para concretos refratários aluminosos?
Sako, E. Y;Milanez, D. H;Braulio, M. A. L;Bittencourt, L. R. M;Pandolfelli, V. C;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000100005
Abstract: considering that developments on refractories performance are of utmost importance to the steel industry advances, thermo-mechanical properties and the corrosion and slag penetration resistance of the lining material are constantly being improved to extend steel ladle working life. these benefits could be attained in high alumina refractory castable by adding pre-formed spinel or magnesia, in order to result in the latter condition in in-situ spinel during the first use of the lining. the objective of the present work was to compare between high alumina castables with pre-formed or in situ spinel in order to verify their main properties differences. in addition, pre-formed spinel was used as aggregate replacing tabular alumina in alumina-magnesia compositions to analyze the effect of coarse particles in the expansion behavior of this type of castable. the results showed higher expansion and better mechanical performance for castables with in-situ spinel after firing at 1500 oc. also, the use of different aggregates in the same composition resulted in distinct expansion values.
Varia??o do tamanho de gr?o da magnésia: um exemplo da complexidade de ceramicas refratária
Braulio, M. A. L.;Milanez, D. H.;Sako, E. Y.;Bittencourt, L. R. M.;Pandolfelli, V. C.;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000300003
Abstract: the expansive behavior of alumina-magnesia refractory castable, attributed to the in-situ spinel formation, is affected by the magnesia source and its grain size. in the present work, increasing mgo grain size induced cracking, and, consequently, reduced the mechanical properties as a result of a large expansion. scanning electron microscopy evaluations after firing at 1500 oc showed distinct microstructures for castables containing different grain sizes (< 45 μm and < 100 μm). for the composition with finer magnesia, phases commonly detected in the literature were observed: spinel and ca6. nevertheless, besides those two phases, the castable with the coarse magnesia also presented forsterite and monticellite around the magnesia remaining grains. hence, the objective of this work is to analyze how the refractory castable properties could be considerably affected even by changing a single parameter: the magnesia grain size.
Agentes ligantes e seus efeitos em concretos refratários alumina-magnésia
Braulio, M. A. L.;Milanez, D. H.;Sako, E. Y.;Bittencourt, L. R. M.;Pandolfelli, V. C.;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000400003
Abstract: the usual binder of alumina-magnesia castables is the calcium aluminate cement. due to in-situ spinel (mgal2o4) formation at high temperatures, these materials present an expansive behavior. when bonded with cement, further reactions (ca2 and ca6 formation) also contribute to the overall expansion. changing the most common cement used (~ 30 wt.% cao) for other containing less calcia (~ 20 wt.% cao) or for hydratable alumina are suitable alternatives for controlling the castables' volumetric stability. nevertheless, the binder replacement may affect castables properties, such as cold mechanical strength, mgo hydration degree and properties during and after sintering. therefore, the objective of the present paper is to analyze the effects of these binders on the alumina-magnesia castables processing. as a result, the binder systems can be used as a tool for designing the alumina-magnesia castables expansion, increasing the flexibility on the selection of steel ladles linings.
Using a Caesarean Section Classification System based on characteristics of the population as a way of monitoring obstetric practice
Maria L Costa, Jose G Cecatti, Jo?o P Souza, Helaine M Milanez, Metin A Gülmezoglu
Reproductive Health , 2010, DOI: 10.1186/1742-4755-7-13
Abstract: clinical records of all births during two three months-periods were evaluated. Each case of CS was classified into one of ten mutually exclusive categories according to obstetric characteristics. The proportion of CS in each group was compared in both periods.total number of deliveries and the high rate of CS were similar in both periods. Group 3 (multiparous excluding previous CS, single, cephalic, ≥ 37 weeks, spontaneous labour) accounted for the largest proportion of deliveries, 28.5 and 26.8% in both periods. Group 1 (nulliparous, single, cephalic, ≥ 37 weeks, spontaneous labour) was the second largest one, while Group 5 (previous caesarean section, single, cephalic, and ≥ 37 weeks) was the third but the largest contributor to CS, accounting for 16.6 and 14.9% among all deliveries in both periods. Groups 2 (nulliparous, single, cephalic, ≥ 37 weeks, induction or CS before labour) and 4 (multiparous excluding previous CS, single, cephalic, ≥ 37 weeks, induction or CS before labour) were less prevalent, however had higher rates of CS. Only in Group 10 (All single, cephalic, ≤ 36 weeks, including previous CS), there was a significant decrease of CS rate from 70.5 to 42.6% between periods.Robson's classification did not identify any significant change in the pattern of CS rates with the audit and feedback process, but showed to be useful for comparing trends among similar obstetric populations.Discussion on caesarean section rates, efforts to prevent its continuous increase and the possibility to allow patients choose their delivery route has been an important topic throughout the world [1].The World Health Organization stated in 1985 that no region should exceed rates higher than 10-15 percent of caesarean sections [2]. However, those goals seem no longer to be greatly achievable, both in developed and developing countries. In fact, the highest increases in Caesarean section rates occurred especially in Latin American countries during the seventies and eighties. Da
Biologia e exigências térmicas de Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) em ovos de Diaphania hyalinata L. (Lepidoptera: Pyralidae)
Melo, Ricardo L.;Pratissoli, Dirceu;Polanczyk, Ricardo A.;Melo, Débora F.;Barros, Reginaldo;Milanez, André M.;
Neotropical Entomology , 2007, DOI: 10.1590/S1519-566X2007000300011
Abstract: the development and parasitism of diaphania hyalinata l. eggs by trichogramma atopovirilia oatman & platner and its thermal requirements were studied at the temperatures of 18, 21, 24, 27, 30 and 33°c. thirty eggs of d. hyalinata were exposed to three females of t. atopovirilia for 5h at 25°c and incubated at the different temperatures. the developmental time from egg exposure to adult, parasitism viability, number of adults per parasitized host egg and progeny sex ratio were monitored. the developmental time from egg to adult emergence of the parasitoid exhibited inverse relationship to the temperature, lasting 24.12 days at 18°c and 7.36 days at 33°c. parasitism viability at 24, 27 and 30°c was higher than 90%. the ratio of t. atapovirilia adult produced per egg and its sex ratio were not affected when using d. hialynata as host. the lowest threshold temperature (tb) and estimated degree-days over tb required by t. atopovirilia to develop on eggs of d. hyalinata was 11.99°c and 130.42oc, respectively. considering the temperature regimes of two areas where cucurbitaces are cultivated in bahia state (rio real and inhambupe county) it was estimated that t. atopovirilia can achieve more than 32 generation per year. the results suggest that t. atopovirilia has potential to control d. hyalinata eggs with better chance of success under temperature regimes ranging from 24 to 27°c that meets the suitable field conditions for cropping cucurbitaces.
Concretos refratários engenheirados com expans?o controlada para panelas de siderurgia
Braulio, M. A. L.;Milanez, D. H.;Sako, E. Y.;Brito, M. A. M.;Bittencourt, L. R. M.;Pandolfelli, V. C.;
Ceramica , 2008, DOI: 10.1590/S0366-69132008000100002
Abstract: thermodynamics and microstructural analysis are of utmost importance to choose the best refractory lining for molten steel containers. in order to extend ladle lining life, thermodynamically stable oxides, such as alumina and magnesia, are essential. at higher temperatures, the in-situ reaction between these two oxides leads to the formation of spinel, which has an outstanding corrosion resistance. due to this reaction, alumina-magnesia castables are liable to a great volume expansion. because of this, controlling the spinel formation is fundamental to keep the integrity of the material. the extent to which this reaction affects the properties of these castables depends on the matrix raw materials. considering this aspect, the aim of this study is to design a residual expansion based on previously engineered microstructure. consequently, the association of chemical resistance and an excellent toughening mechanism can be attained, resulting in materials with better performance.
Leptospira interrogans serovar Copenhageni Harbors Two lexA Genes Involved in SOS Response
Luciane S. Fonseca, Josefa B. da Silva, Juliana S. Milanez, Claudia B. Monteiro-Vitorello, Leonardo Momo, Zenaide M. de Morais, Silvio A. Vasconcellos, Marilis V. Marques, Paulo L. Ho, Renata M. A. da Costa
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076419
Abstract: Bacteria activate a regulatory network in response to the challenges imposed by DNA damage to genetic material, known as the SOS response. This system is regulated by the RecA recombinase and by the transcriptional repressor lexA. Leptospira interrogans is a pathogen capable of surviving in the environment for weeks, being exposed to a great variety of stress agents and yet retaining its ability to infect the host. This study aims to investigate the behavior of L. interrogans serovar Copenhageni after the stress induced by DNA damage. We show that L. interrogans serovar Copenhageni genome contains two genes encoding putative LexA proteins (lexA1 and lexA2) one of them being potentially acquired by lateral gene transfer. Both genes are induced after DNA damage, but the steady state levels of both LexA proteins drop, probably due to auto-proteolytic activity triggered in this condition. In addition, seven other genes were up-regulated following UV-C irradiation, recA, recN, dinP, and four genes encoding hypothetical proteins. This set of genes is potentially regulated by LexA1, as it showed binding to their promoter regions. All these regions contain degenerated sequences in relation to the previously described SOS box, TTTGN 5CAAA. On the other hand, LexA2 was able to bind to the palindrome TTGTAN 10TACAA, found in its own promoter region, but not in the others. Therefore, the L. interrogans serovar Copenhageni SOS regulon may be even more complex, as a result of LexA1 and LexA2 binding to divergent motifs. New possibilities for DNA damage response in Leptospira are expected, with potential influence in other biological responses such as virulence.
Gas chromatography: mass spectrometry determination of trichothecene mycotoxins in commercial corn harvested in the state of S?o Paulo, Brazil
Milanez, Tha?s V.;Valente-Soares, Lúcia M.;
Journal of the Brazilian Chemical Society , 2006, DOI: 10.1590/S0103-50532006000200028
Abstract: the incidence of deoxynivalenol (don), nivalenol (niv), diacetoxyscirpenol (das), and toxins t-2 (t2) and ht-2 (ht2) in 80 samples of commercial corn harvested in the state of s?o paulo, brazil. they were collected in the silos of the two largest corn farmer's cooperatives of this state. the samples were extracted with water/acetonitrile and cleaned-up with mycosep columns. after trifluoroacetic anhydride derivatization the samples were submitted to gas chromatography-mass spectrometry. detection limits ranged from 10 ng g-1 to 40 ng g-1. niv was present in 5 samples and don and niv occurred simultaneously in one sample. das, t2 and ht2 were not detected. this is the first report that shows the prevalence of niv over don in corn harvested in brazil.
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