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Search Results: 1 - 10 of 262037 matches for " W. G. Nunes "
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Application of Photo-Fenton Process for the Treatment of Kraft Pulp Mill Effluent  [PDF]
M. D. Rabelo, C. R. Bellato, C. M. Silva, R. B. Ruy, C. A. B. da Silva, W. G. Nunes
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.44050
Abstract: The present work evaluated the use of photo-Fenton process for the treatment of kraft pulp mill effluent. The photo-Fenton best operating conditions, such as pH, concentration, and H2O2: Fe2+ ratio were evaluated. The efficiency of the treatment was measured by COD (chemical oxygen demand) removal. The results showed that the optimum pH for the photo-Fenton process was equal to 3. The increase in H2O2 application resulted in an efficiency increase of the photo-Fenton process, although this was not a directly proportional relation. For most cases, the H2O2: Fe2+ proportion of 100:1 yielded the best results for COD removal. Solar radiation was more efficient than artificial UV to the COD removal. During the treatment the organic matter of the effluent was more oxidized than mineralized, showing a higher removal of COD than BOD (biochemical oxygen demand) and TOC (total organic carbon), respectively. So, photo-Fenton process increased the BOD/ COD ration but decreased the BOD/TOC ratio.
Serological survey for canine cutaneous and visceral leishmaniasis in areas at risk for transmission in Rio de Janeiro where prophylatic measures had been adopted
Nunes, M. P.;Jackson, J. M.;Carvalho, R. W.;Furtado, N. J.;Coutinho, S. G.;
Memórias do Instituto Oswaldo Cruz , 1991, DOI: 10.1590/S0074-02761991000400006
Abstract: a serological survery for canine visceral (vl) and american cutaneous leishmaniasis (acl) has been carried out during 1984-1989, to assess the effects of the prophylactic measures adopted in areas where there was a risk of transmission of the diseases in rio de janeiro. a previous serologival survey (1982/83) had detected serum positive dogas as well as the human disease in these same areas. a total fo 22,828 dogs have been examined in this last survey, 7,807 of which came from campo grande (vl and acl area), 4,110 from jacarepaguá (acl area), 4,l46 from realengo, 3,879 from bangu and 2,886 from senador camará, (three vl areas). the analysis of these results showed a notable reduction in the number of serum positve dogs, compared to those of the first survey was 12.7%, against 0.62% of the second; (b) in jacarepaguá (acl) it decreased from 8.6%) to l.8% (c) in bangu, realengo and senador camará (vl) the rate decreased from 4.3% to 0.38%. the results indicate that this decrease was due to the prophylactic measures adopted in those areas.
Coupling and higher-order effects in the 12C(d,p)13C and 13C(p,d)12C reactions
F. Delaunay,F. M. Nunes,W. G. Lynch,M. B. Tsang
Physics , 2005, DOI: 10.1103/PhysRevC.72.014610
Abstract: Coupled channels calculations are performed for the 12C(d,p)13C and 13C(p,d)12C reactions between 7 and 60 MeV to study the effect of inelastic couplings in transfer reactions. The effect of treating transfer beyond Born approximation is also addressed. The coupling to the 12C 2+ state is found to change the peak cross-section by up to 15 %. Effects beyond Born approximation lead to a significant renormalization of the cross-sections, between 5 and 10 % for deuteron energies above 10 MeV, and larger than 10 % for lower energies. We also performed calculations including the remnant term in the transfer operator, which has a small impact on the 12C(d,p)13C(g.s.) and 13C(p,d)12C(g.s.) reactions. Above 30 MeV deuteron energy, the effect of the remnant term is larger than 10 % for the 12C(d,p)13C(3.09 MeV) reaction and is found to increase with decreasing neutron separation energy for the 3.09 MeV state of 13C. This is of importance for transfer reactions with weakly bound nuclei.
An order-N study of dislocations in homopolar semiconductors
Nunes, R.W.;
Brazilian Journal of Physics , 1999, DOI: 10.1590/S0103-97331999000400009
Abstract: this article surveys the main results of the author's work, in collaboration with david vanderbilt and john bennetto, on the application of the order-n density-matrix approach, together with ab initio methods, to investigate the atomic structure of dislocation cores in the homopolar semiconductors silicon, carbon, and germanium. in these systems, the predominant dislocations are the 30° and the 90° partial dislocations. for the three materials, the nature of the reconstruction at the core of the 90°-partial dislocation is considered. both the traditional single-period and our recently proposed double-period core structures are investigated. the double-period geometry is found to be the ground-state structure in all three cases. for silicon, we have also investigated in detail the structure and dynamics of point excitations (kinks, solitons, and kink-soliton complexes) in the cores of the 30° partial dislocation and the single-period geometry of the 90° partial. our calculated formation energies and migration barriers for these excitations are in good agreement with available experimental results. furthermore, we have examined the reactions by which high-energy kinks relax into low-energy ones by soliton emission.
An order-N study of dislocations in homopolar semiconductors
Nunes R.W.
Brazilian Journal of Physics , 1999,
Abstract: This article surveys the main results of the author's work, in collaboration with David Vanderbilt and John Bennetto, on the application of the order-N density-matrix approach, together with ab initio methods, to investigate the atomic structure of dislocation cores in the homopolar semiconductors silicon, carbon, and germanium. In these systems, the predominant dislocations are the 30° and the 90° partial dislocations. For the three materials, the nature of the reconstruction at the core of the 90°-partial dislocation is considered. Both the traditional single-period and our recently proposed double-period core structures are investigated. The double-period geometry is found to be the ground-state structure in all three cases. For silicon, we have also investigated in detail the structure and dynamics of point excitations (kinks, solitons, and kink-soliton complexes) in the cores of the 30°partial dislocation and the single-period geometry of the 90° partial. Our calculated formation energies and migration barriers for these excitations are in good agreement with available experimental results. Furthermore, we have examined the reactions by which high-energy kinks relax into low-energy ones by soliton emission.
Lux in Práxis
Ruben G. Nunes
Princípios : Revista de Filosofia , 1994,
Abstract:
Parametros da degrada??o protéica ruminal de diferentes alimentos e ra??es estimados por técnica in vitro
Lana, R.P.;Leopoldino, W.M.;Oliveira, J.S.;Veloso, R.G.;Nunes, P.M.M.;Queiroz, A.C.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2007, DOI: 10.1590/S0102-09352007000200023
Abstract: three experiments were carried out in order to study the parameters of ruminal protein degradation. in the first, isoproteic diets, constituted of elephant grass, ground corn and soybean meal, at five concentrate levels (0:100, 25:75, 50:50, 75:25 e 100:0), with or without monensin (5μm), were incubated in ruminal fluid of bovines. there was a decreasing linear effect of the concentrate level on ammonia concentration and degradability of crude protein, and cubic effect in soluble protein concentration, with the largest value in the diet with 25% concentrate. monensin decreased degradability of crude protein and soluble protein concentration with no effect on ammonia production. in the second, five different roughages (corn and elephant grass silage - pennisetum purpureum, brachiaria haylage - brachiaria decumbens, ammoniated tifton 85 hay - cynodon sp. e tifton 85 hay). the were incubated brachiaria haylage and the ammoniated tifton 85 hay showed the greatest concentrations of ammonia (8.7 and 5.3mg/dl) and soluble protein (5.4 and 7.0mg/dl), due to their higher crude protein content, followed by elephant grass silage and tifton 85 hay. the degradability of crude protein ranged from 29.6 to 80.6% for brachiaria haylage and tifton 85 hay, and the degradability of dry matter ranged from 40.1 to 64.3% for elephant grass silage and brachiaria haylage, respectively. the effective degradability of crude protein showed low values due to low degradation rate of the insoluble fraction. in the third, four different poultry litter (hulls coffee, shopped dry elephant grass, corn cobs and wood shavings) were incubated, with or without monensin (5μm). no difference in ammonia concentration among the poultry litter samples, was observed in the absence of monensin. however, when monensin was present, the grass poultry litter showed the lowest ammonia level and wood poultry litter the highest. the poultry litter influenced the soluble protein content and the degradability of crude p
Atividade antimicrobiana de bactérias ácido-lácticas isoladas de queijos de coalho artesanal e industrial frente a microrganismos indicadores
Guedes Neto, L.G.;Souza, M.R.;Nunes, A.C.;Nicoli, J.R.;Santos, W.L.M.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2005, DOI: 10.1590/S0102-09352005000800017
Abstract: four strains of lactobacillus spp. and two strains of lactococcus spp. were isolated from artisanal and industrial "coalho" cheese and tested for inhibitory activity. it was observed antagonistic activity of the lactic acid bacteria against themselves and other lactic acid bacteria and pathogens isolated from the same cheese samples, as well as against pathogenic strains from other sources. significant difference (p<0.05) was observed among the antagonistic activities, except when lactic acid bacteria were used as indicator. from the tested bacteria, lactobacillus spp. showed the strongest antagonistic activity.
Active replication of hepatitis B virus (HBV) in HIV type 1 and in HIV type 2 infected patients
Barros, M.F.;Piedade, J.;Nunes, G.;Canas-Ferreira, W.;Silva, A.P.;Champalimaud, J.L.;Machado-Caetano, J.A.;
Revista do Instituto de Medicina Tropical de S?o Paulo , 1996, DOI: 10.1590/S0036-46651996000400003
Abstract: to evaluate the effect of concurrent infection by hiv on hbv infection or immunity, we have studied a group of 66 hiv1+ symptomatic caucasian patients and another of 38 african hiv2+ asymptomatic individuals, concerning their hbv status: serological markers of infection and presence of hbv-dna in serum, the last taken as sign of hepatitis b virus active replication, were monitored. hiv+ groups were compared with seronegative controls, adequately matched for age, sex and ethnological background. hbv dna was found in 7.6% of hiv1+ caucasian patients and 3.2% of seronegative controls; in african hiv2+ individuals 2.6% were also hbv dna+, a percentage close to that found in hiv2 seronegative controls (2.9%). no correlation was found between hiv infection and hbv active replication. immunodepression that follows hiv infection over time may be compatible with a degree of t cell function capable of avoiding reinfection with or reactivation of hbv, even in symptomatic stages of acquired immunodeficiency syndrome. our findings are relevant to the choice of preventive strategies in populations at risk for hiv and hbv infection.
Real-space approach to calculation of electric polarization and dielectric constants
R. W. Nunes,David Vanderbilt
Physics , 1994, DOI: 10.1103/PhysRevLett.73.712
Abstract: We describe a real-space approach to the calculation of the properties of an insulating crystal in an applied electric field, based on the iterative determination of the Wannier functions (WF's) of the occupied bands. It has been recently shown that a knowledge of the occupied WF's allows the calculation of the spontaneous (zero-field) electronic polarization. Building on these ideas, we describe a method for calculating the electronic polarization and dielectric constants of a material in non-zero field. The method is demonstrated for a one-dimensional tight-binding Hamiltonian.
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