We experimentally tested threealternative hypotheses to explain the low algaldiversity and abunda... more We experimentally tested threealternative hypotheses to explain the low algaldiversity and abundance in an intertidal zonereceiving the effluents of the copper mine El Salvadorin northern Chile. Our results demonstrated thatalgae were able to grow at the levels of dissolvedcopper detected in coastal waters of the area. Duringthe assays, growth and regeneration in several red,green and brown adult algae and juvenile
An experiment was conducted for six months to demonstrate the suitability of biofloc technology i... more An experiment was conducted for six months to demonstrate the suitability of biofloc technology in farming system of mono-sex GIFT tilapia Oreochromis niloticus. The experiment was carried out with four treatments and three replicates of each. Three supplemental feeds such as commercial tilapia feed (CF), wheat bran (WB), biofloc technology (BFT) and rice bran + wheat bran (50:50) (RWB)were designated for this experimentation. The stocking density was 125 fingerlings/decimal with a mean initial weight of 2.80±0.03 g of each. Fish were fed at the rate of 6% of fish body weight at the beginning. The feeding rate was gradually reduced to 2% in the third month and finally increased to 3% for rest of the period. After 6 months of rearing, mono-sex GIFT tilapia in CF attained a significantly (P<0.05) higher mean final weight (150.61±7.47 g) and specific growth rate (3.32±0.05) than those of WB, BFT and RWB, respectively. However, there was no significant (P>0.05) difference in survi...
Charged chromophores based on heteroaromatic cations were prepared by reaction of alkylazinium sa... more Charged chromophores based on heteroaromatic cations were prepared by reaction of alkylazinium salts with N-heteroarylstannanes under Stille conditions. This approach provides easy access to potential single donor D-A(+) chromophores in which the acceptor moiety A(+) is the pyridinium cation and the donors are different π-excessive N-heterocycles. The β hyperpolarizabilities were measured in hyper-Rayleigh scattering experiments and the experimental data are supported by a theoretical analysis that combines a variety of computational procedures, including density functional theory and correlated Hartree-Fock-based methods. In some chromophores, the absence of a bridge between donor and acceptor fragments increases the NLO properties.
During the last decade, Cienfuegos Bay, in the southern coastal zone of Cuba, has undergone major... more During the last decade, Cienfuegos Bay, in the southern coastal zone of Cuba, has undergone major economic and social development, resulting in an increase of industrial and domestic wastes discharged into the bay. Levels of copper, iron, mercury, manganese ...
The technique of order of magnitude scaling (OMS) (1) has been applied to the mathematical modeli... more The technique of order of magnitude scaling (OMS) (1) has been applied to the mathematical modeling of a long electric arc. The estimations obtained are combined with numerical calculations, thus important features of both techniques are considered simultaneously: the high precision of numerical modeling, and the generality and simplicity of algebraic expressions. Power-law expressions for the estimations of length of the transition region, maximum radial and axial velocity, maximum pressure in the cathode spot, maximum temperature in the column and arc radius are obtained and are consistent with previous theoretical and experimental work. The calculations of arc temperature differ from channel models of the arc by considering the heat transfer in the gas region surrounding the arc.
We experimentally tested threealternative hypotheses to explain the low algaldiversity and abunda... more We experimentally tested threealternative hypotheses to explain the low algaldiversity and abundance in an intertidal zonereceiving the effluents of the copper mine El Salvadorin northern Chile. Our results demonstrated thatalgae were able to grow at the levels of dissolvedcopper detected in coastal waters of the area. Duringthe assays, growth and regeneration in several red,green and brown adult algae and juvenile
An experiment was conducted for six months to demonstrate the suitability of biofloc technology i... more An experiment was conducted for six months to demonstrate the suitability of biofloc technology in farming system of mono-sex GIFT tilapia Oreochromis niloticus. The experiment was carried out with four treatments and three replicates of each. Three supplemental feeds such as commercial tilapia feed (CF), wheat bran (WB), biofloc technology (BFT) and rice bran + wheat bran (50:50) (RWB)were designated for this experimentation. The stocking density was 125 fingerlings/decimal with a mean initial weight of 2.80±0.03 g of each. Fish were fed at the rate of 6% of fish body weight at the beginning. The feeding rate was gradually reduced to 2% in the third month and finally increased to 3% for rest of the period. After 6 months of rearing, mono-sex GIFT tilapia in CF attained a significantly (P<0.05) higher mean final weight (150.61±7.47 g) and specific growth rate (3.32±0.05) than those of WB, BFT and RWB, respectively. However, there was no significant (P>0.05) difference in survi...
Charged chromophores based on heteroaromatic cations were prepared by reaction of alkylazinium sa... more Charged chromophores based on heteroaromatic cations were prepared by reaction of alkylazinium salts with N-heteroarylstannanes under Stille conditions. This approach provides easy access to potential single donor D-A(+) chromophores in which the acceptor moiety A(+) is the pyridinium cation and the donors are different π-excessive N-heterocycles. The β hyperpolarizabilities were measured in hyper-Rayleigh scattering experiments and the experimental data are supported by a theoretical analysis that combines a variety of computational procedures, including density functional theory and correlated Hartree-Fock-based methods. In some chromophores, the absence of a bridge between donor and acceptor fragments increases the NLO properties.
During the last decade, Cienfuegos Bay, in the southern coastal zone of Cuba, has undergone major... more During the last decade, Cienfuegos Bay, in the southern coastal zone of Cuba, has undergone major economic and social development, resulting in an increase of industrial and domestic wastes discharged into the bay. Levels of copper, iron, mercury, manganese ...
The technique of order of magnitude scaling (OMS) (1) has been applied to the mathematical modeli... more The technique of order of magnitude scaling (OMS) (1) has been applied to the mathematical modeling of a long electric arc. The estimations obtained are combined with numerical calculations, thus important features of both techniques are considered simultaneously: the high precision of numerical modeling, and the generality and simplicity of algebraic expressions. Power-law expressions for the estimations of length of the transition region, maximum radial and axial velocity, maximum pressure in the cathode spot, maximum temperature in the column and arc radius are obtained and are consistent with previous theoretical and experimental work. The calculations of arc temperature differ from channel models of the arc by considering the heat transfer in the gas region surrounding the arc.
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Papers by Marco Antonio Bravo Ramirez