Manuel Velasco - Academia.edu (original) (raw)

Papers by Manuel Velasco

Journal of soil science and plant nutrition, 2012

The aim of this work was to evaluate, through different analytical techniques, the evolution of s... more The aim of this work was to evaluate, through different analytical techniques, the evolution of some chemical and physicochemical properties of humic acid (HA)-like fraction extracted from an organic amendment, like rabbit manure, handle with composting followed by vermicomposting process, in comparison with soil HA, in order to reach an appropriate criterion to evaluate the maturity of an organic amendment. The raw material used was rabbit manure treated with composting followed by vermicomposting process. Soil and organic amendments were analyzed by chemical properties. The HA was extracted from the amendments samples and from an Entic Haplustol and analyzed the chemical and physicochemical characteristics by several analytical methods. Through these analytical techniques was possible to follow the evolution of the HAlike fraction during this stabilization-maturation process Through the composting followed by vermicomposting process the HA-like fraction are evolving toward more stable and complex macromolecule resembling native soil HA.

Soil Health and Land Use Management, 2012

sampling in the unburned and burned soil, respectively. The soil was taxonomically characterized ... more sampling in the unburned and burned soil, respectively. The soil was taxonomically characterized as Ustorthent. The samples were air-dried, crushed and passed through a 2 mm sieves before all the analytical analysis The humic acids (HA) analyzed were extracted from the burned (HA-BS) and unburned soil (HA-UBS) 2.2 Methods The samples of burned and unburned soil were analyzed for pH at a rate 1:2.5 (w:v), electric conductivity (EC), total nitrogen content (TN) by the Kjeldahl method, phosphorus available (P) by Bray & Kurtz method (1945), total organic carbon (TOC) by combustion at 540 0 C for 4 h (Abad, et al., 2002) and oxidable carbon (Cox) by the methodology proposed by de Richter & Von Wistinghausen (1981). Organic light fraction (OLF) were determined according the method proposed by Janzen et al., 1992, the C and N content of the OLF by dry combustion using a Perkin Elmer CN Elemental Analizer. The carbon content of humic substances (CHS), humic acids (CHA) and fulvic acids (CFA) were determined according to the technique proposed by Syms & Haby 1971. The carbon content of each fraction (CHS, CHA and CFA) were calculated as percentage of the TOC, therefore, the % CHA correspond to the Humification Index (HI) (Roletto et al., 1985; Ciavatta et al., 1988). The apolar or free lipidic fraction (FLF) were extracted with petroleum ether (40-60 0 C) in 250 ml Soxhtel loaded with 50 g of soil; the extraction phase was renewed every 12h. The total extract was dehydrated with anhydrous Na 2 SO 4 evaporated under reduced pressure to approximately 50 ml, dried under N 2 stream at room temperature (20-25 0 C), and finally weighted, following the methodology proposed by Zancada et al., 2004. The spectroscopy characteristics of the alkaline extract of both soil samples, the absorbance at different wavelength (280, 470 y 664 nm), were determined by the methodology proposed by Sapeck & Sapeck (1999). The ratio E2/E6, E4/E6 and E4/E6 were calculated from the corresponding absorbance value of the alkaline extract. The measures were determined using Spectronic 20 Genesys Spectrophotometer. 2.2.1 Humic Acids isolation HA from burned and unburned soil were extracted with NaOH 0.1 mol L-1 , purified with HCl:HF (1:3) and dried at low temperature until constant weight, according to the procedure recommended by Chen et al. (1978). All solutions were prepared with tridistilled water and all the reagents were ACS reagent grade. 2.2.2 Humic Acids analyses HA ash content was measured by heating it at 550 0 C for 24 h. The elemental composition for C, H, N, S was determined by an analyzer instrument Carlo Erba 1108, using isothiourea as standard. Oxygen was calculated by difference: O%= 100-(%C+%H+%N+%S) (ash and moisture-free basis). 2.2.3 Spectroscopic characteristics The absorbance of the extracted HA were measured on a solution containing 3.0 mg of each HA in 10 mL of 0.05 mol L-1 NaHCO 3 at different wavelength (280, 470 y 664 nm) www.intechopen.com

Ciência e Tecnologia de Alimentos, 2011

Chemical and physicochemical characteristics changes during passion fruit juice processing Altera... more Chemical and physicochemical characteristics changes during passion fruit juice processing Alterações das características químicas e físico-químicas durante as etapas de processamento do suco de maracujá

Revista Latinoamericana de Hipertension

Background and Purpose Cigarette smoking has been associated with the development of cardiovascul... more Background and Purpose Cigarette smoking has been associated with the development of cardiovascular disease and cancer. Even though the molecular mechanism is not clear yet, it has been related to the oxygen free radicals. Thus, the main objective of this study was to establish the changes in the oxidation/antioxidation balance induced by cigarette smoking. Methods 30 healthy subjects (15 smokers and 15 non smokers) of both genders were studied. The smokers group had smoked a mean of 14 cigarettes per day during 4.5 years. Fasting serum levels of malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH) and vitamin C (ascorbic and dehydroascorbic acid) were measured. Results Fasting NO concentration was significantly higher in smokers (51.3 ± 5.3 µM) than non-smokers (35.2 ± 4.8 µM, p

Journal of soil science and plant nutrition, 2012

The aim of this work was to evaluate, through different analytical techniques, the evolution of s... more The aim of this work was to evaluate, through different analytical techniques, the evolution of some chemical and physicochemical properties of humic acid (HA)-like fraction extracted from an organic amendment, like rabbit manure, handle with composting followed by vermicomposting process, in comparison with soil HA, in order to reach an appropriate criterion to evaluate the maturity of an organic amendment. The raw material used was rabbit manure treated with composting followed by vermicomposting process. Soil and organic amendments were analyzed by chemical properties. The HA was extracted from the amendments samples and from an Entic Haplustol and analyzed the chemical and physicochemical characteristics by several analytical methods. Through these analytical techniques was possible to follow the evolution of the HAlike fraction during this stabilization-maturation process Through the composting followed by vermicomposting process the HA-like fraction are evolving toward more stable and complex macromolecule resembling native soil HA.

Soil Health and Land Use Management, 2012

sampling in the unburned and burned soil, respectively. The soil was taxonomically characterized ... more sampling in the unburned and burned soil, respectively. The soil was taxonomically characterized as Ustorthent. The samples were air-dried, crushed and passed through a 2 mm sieves before all the analytical analysis The humic acids (HA) analyzed were extracted from the burned (HA-BS) and unburned soil (HA-UBS) 2.2 Methods The samples of burned and unburned soil were analyzed for pH at a rate 1:2.5 (w:v), electric conductivity (EC), total nitrogen content (TN) by the Kjeldahl method, phosphorus available (P) by Bray & Kurtz method (1945), total organic carbon (TOC) by combustion at 540 0 C for 4 h (Abad, et al., 2002) and oxidable carbon (Cox) by the methodology proposed by de Richter & Von Wistinghausen (1981). Organic light fraction (OLF) were determined according the method proposed by Janzen et al., 1992, the C and N content of the OLF by dry combustion using a Perkin Elmer CN Elemental Analizer. The carbon content of humic substances (CHS), humic acids (CHA) and fulvic acids (CFA) were determined according to the technique proposed by Syms & Haby 1971. The carbon content of each fraction (CHS, CHA and CFA) were calculated as percentage of the TOC, therefore, the % CHA correspond to the Humification Index (HI) (Roletto et al., 1985; Ciavatta et al., 1988). The apolar or free lipidic fraction (FLF) were extracted with petroleum ether (40-60 0 C) in 250 ml Soxhtel loaded with 50 g of soil; the extraction phase was renewed every 12h. The total extract was dehydrated with anhydrous Na 2 SO 4 evaporated under reduced pressure to approximately 50 ml, dried under N 2 stream at room temperature (20-25 0 C), and finally weighted, following the methodology proposed by Zancada et al., 2004. The spectroscopy characteristics of the alkaline extract of both soil samples, the absorbance at different wavelength (280, 470 y 664 nm), were determined by the methodology proposed by Sapeck & Sapeck (1999). The ratio E2/E6, E4/E6 and E4/E6 were calculated from the corresponding absorbance value of the alkaline extract. The measures were determined using Spectronic 20 Genesys Spectrophotometer. 2.2.1 Humic Acids isolation HA from burned and unburned soil were extracted with NaOH 0.1 mol L-1 , purified with HCl:HF (1:3) and dried at low temperature until constant weight, according to the procedure recommended by Chen et al. (1978). All solutions were prepared with tridistilled water and all the reagents were ACS reagent grade. 2.2.2 Humic Acids analyses HA ash content was measured by heating it at 550 0 C for 24 h. The elemental composition for C, H, N, S was determined by an analyzer instrument Carlo Erba 1108, using isothiourea as standard. Oxygen was calculated by difference: O%= 100-(%C+%H+%N+%S) (ash and moisture-free basis). 2.2.3 Spectroscopic characteristics The absorbance of the extracted HA were measured on a solution containing 3.0 mg of each HA in 10 mL of 0.05 mol L-1 NaHCO 3 at different wavelength (280, 470 y 664 nm) www.intechopen.com

Ciência e Tecnologia de Alimentos, 2011

Chemical and physicochemical characteristics changes during passion fruit juice processing Altera... more Chemical and physicochemical characteristics changes during passion fruit juice processing Alterações das características químicas e físico-químicas durante as etapas de processamento do suco de maracujá

Revista Latinoamericana de Hipertension

Background and Purpose Cigarette smoking has been associated with the development of cardiovascul... more Background and Purpose Cigarette smoking has been associated with the development of cardiovascular disease and cancer. Even though the molecular mechanism is not clear yet, it has been related to the oxygen free radicals. Thus, the main objective of this study was to establish the changes in the oxidation/antioxidation balance induced by cigarette smoking. Methods 30 healthy subjects (15 smokers and 15 non smokers) of both genders were studied. The smokers group had smoked a mean of 14 cigarettes per day during 4.5 years. Fasting serum levels of malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH) and vitamin C (ascorbic and dehydroascorbic acid) were measured. Results Fasting NO concentration was significantly higher in smokers (51.3 ± 5.3 µM) than non-smokers (35.2 ± 4.8 µM, p