A DFT Approach for Methanol Synthesis via Hydrogenation of CO on Gallia, Ceria and ZnO surfaces

A systematic theoretical study of the consecutive hydrogenation reactions of the CO molecule for the methanol synthesis catalyzed by different oxides of Zn, Ce and Ga is reported in this work. First, the CO hydrogenation with the formation of formyl species (HCO) was analyzed, followed by the successive hydrogenations that lead to formaldehyde (H2CO), methoxy (H3CO) and, finally, methanol (H3COH). The co-adsorption with H, in almost all the intermediate species, allows the corresponding hydrogenation reaction. Oxygen vacancies promote the reactivity in the generation of both formaldehyde and methoxy species. The formation of these species involves an important geometric difference between the initial and the final states, leading to high activation barriers. Comparing the surfaces studied in this work, we found that ZnO (0001)vacO has shown to be of a greater interest for methanol synthesis. However, the foregoing is not the most relevant of our results, but, instead, that the Brönsted Evans Polanyi (BEP) relationships between the initial or the final states and the transition states (TS) allowed to find a very good correlation between surface structure and reactivity.Fil: Reimers, Walter Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Zubieta, Carolina Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Baltanas, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Branda, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin

In vitro fermentation profile and methane production of Kikuyu grass harvested at different sward heights

Highly digestible forages are associated with an in vitro low-methane (CH4) rumen fermentation profile and thus the possibility of reducing CH4 emissions from forage-based systems. We aimed to assess the in vitro ruminal fermentation profile, including CH4 production, of the top stratum of Kikuyu grass (Cenchrus clandestinus - Hochst. ex Chiov) harvested at different sward heights (10, 15, 20, 25, and 30 cm). Herbage samples (incubating substrate) were analyzed for their chemical composition, in vitro organic matter digestibility (IVOMD), and morphological components. In vitro incubations were performed under a randomized complete block design with four independent runs of each treatment. Gas production (GP), in vitro dry matter digestibility (IVDMD), CH4 production, total volatile fatty acid (VFA) concentration, and their acetate, propionate, and butyrate proportions were measured following 24 and 48 hours of incubation. Herbage samples had similar contents of organic matter, neutral detergent fiber, and crude protein for all treatments. However, a higher acid detergent fiber (ADF) content in taller sward heights than in smaller sward heights and a tendency for metabolizable energy (ME) and IVOMD to decrease as sward height increased were found. Similarly, the stem + sheath mass tended to increase with increasing sward height. Amongst the nutrients, ME (r = –0.65) and IVDMD (r = –0.64) were negatively correlated with sward height (p < 0.001) and ADF was positively correlated with sward height (r = 0.73, p < 0.001). Both the GP and IVDMD were negatively related to the sward height at both incubation times. Sward heights of Kikuyu grass below 30 cm display an in vitro profile of VFAs high in propionate and low in acetate, with a trend toward lower methane production of CH4 per unit of IVDMD. These findings are important to aid decision-making on the optimal sward height of Kikuyu grass and manage animal grazing with the opportunity to reduce CH4 production

Una innovación en el manejo del pastoreo como estrategia para mejorar la producción animal y reducir las emisiones de GEI

En Colombia, Debido a que el crecimiento del sector ganadero parece no solo inevitable sino también deseable para la economía, el empleo y la alimentación (FCRN, 2017), los sistemas de pastoreo están ahora siendo rediseñados para conciliar la producción con el manejo ambiental y así mejorar su eficiencia general (Carvalho, 2013). La intensificación de los sistemas de producción ganadera se considera como una estrategia importante para mitigar las emisiones antropogénicas de GEI (Gerber et al., 2013) y la mejora el manejo del pastoreo un enfoque eficaz para aumentar la productividad animal y reducir las emisiones de GEI (particularmente CH4) por unidad de producto animal o por área. Para lograr estas metas, objetivos relacionados con el manejo del pastoreo que optimizen el consumo de nutrientes por unidad de tiempo y aumenten la eficiencia de la utilización de los pastizales, deben ser redefinidos

Grazing management innovation as a strategy to improve animal production and reduce GHG emissions

In Colombia, livestock growth appears to be not only inevitable but also desirable for the economy, jobs, and nutrition (FCRN, 2017), grazing systems are now being re-designed to conciliate production with environmental management and improve overall efficiency (Carvalho, 2013). Intensification of cattle production systems is considered as an important strategy for mitigating anthropogenic GHG emissions (Gerber et al. 2013), and improving grazing management is an effective approach for increasing animal productivity while reducing GHG emissions (particularly CH4) per unit of animal product or per unit area. To accomplish these goals, grazing management targets to optimize nutrient consumption per unit of eating time and increase pasture utilization efficiency should be redefined

Low-intensity, high-frequency grazing positively affects defoliating behavior, nutrient intake and blood indicators of nutrition and stress in sheep

The intensity and frequency of grazing affect the defoliating strategy of ruminants, their daily nutrient intake, thus nutrition and physiological status. Italian ryegrass (Lolium multiflorum Lam.) pastures were grazed by sheep either under a low-intensity/high-frequency grazing strategy (Rotatinuous stocking; RN) with nominal pre- and post-grazing sward heights of 18 and 11 cm, respectively, or under a high-intensity/low-frequency strategy (traditional rotational stocking; RT) with nominal pre- and post-grazing sward heights of 25 and 5 cm, respectively. Treatments were arranged under a complete randomized design and evaluated over two periods, in different years. In 2017, the aim was to depict the type of bites that sheep perform during the grazing-down and associate them to the grazing management strategy according to their relative contribution to the diet ingested. In 2018 we estimated the total nutrient intake and evaluated blood indicators of the nutritional status and immune response to stress of sheep. The bite types accounting the most for the diet ingested by RN sheep were those performed on the “top stratum” of plants with around 20, 15, and 25 cm, whereas the type of bites accounting the most for the diet of RT sheep were those performed on “grazed plants” with around 10, 5, and ≤ 3 cm. In 2018, the RN sheep increased by 18% the total organic matter (OM) intake and by 20–25% the intake of soluble nutrients (i.e., crude protein, total soluble sugars, crude fat), digestible OM and of metabolizable energy, and had 17.5, 18, and 6.1% greater blood concentration of glucose, urea nitrogen (BUN) and albumin, respectively, but 17% lower blood neutrophil-to-lymphocyte (N:L) ratio. Sheep grazing vegetative Italian ryegrass pastures under the low-intensity/high-frequency grazing strategy (RN) ingested a diet of better quality from bites allocated on the top stratum of plants, had greater intake of soluble nutrients and blood parameters positively associated with nutritional status and immune response to stress

Bioethanol production from grain sorghum (sorghum bicolor l. moench) at laboratory scale

En el presente trabajo se investigó la producción de bioetanol a partir de sorgo granífero, en respuesta a la necesidad de explorar otros materiales para obtener alcohol por fermentación. Se diseñó un protocolo experimental de laboratorio para evaluar el rendimiento en bioetanol en 7 genotipos. La producción de bioetanol varió de 428,13 a 481,5 ml.kg MS­1 después de 68 horas de fermentación. Los genotipos INTA Blanco y Antel INTA expresaron un rendimiento en bioetanol significativamente diferente. En esta investigación no pudo determinarse el efecto de las propiedades particulares del grano sobre la bioconversión. El alto rendimiento de bioetanol demuestra que el sorgo granífero puede ser una alternativa para diferentes regiones, ya que es un cultivo que se adapta a diferentes tipos de suelos y clima.The production of ethanol from grain sorghum was investigated in the present work, in response to the need of exploring other materials to obtain alcohol by fermentation. A laboratory experimental protocol was designed in order to evaluate ethanol yield, from grain in 7 genotypes. The ethanol production varied from 428,13 to 481,5 ml.kg MS­1 at 68 hours of fermentation. INTA Blanco and Antel INTA genotypes significantly differed in ethanol yield. Through this research it was not possible to determine the impact of particular grain properties on bioconversion. The high ethanol yield demonstrated that grain sorghum can be an alternative for different regions, since it is a crop that adapts to different soil types and climate.Fil: Picca, Aurora Maria Teresita. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Castaño Zubieta, Mirta Raquel. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Isasti, Julián José. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pereyra Cardozo, María Clementina. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Fernandez, Miguel Angel. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Ferrari, Enzo David. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Domínguez, Rodolfo. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Paccapelo, Hector Antonio. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentin

Determining the pre-grazing sward height of Kikuyu grass (Cenchrus clandestinus - Hochst. ex Chiov.) for optimizing nutrient intake rate of dairy heifers.

peer reviewedUnderstanding the grazing process and animal response to sward structures (e.g., sward height) is key to setting targets for efficient grazing management. We hypothesized that the short-term intake rate (STIR) of dry matter (DM) and digestible organic matter (OM) by dairy heifers is maximized with Kikuyu grass (Cenchrus clandestinus-Hochst. ex Chiov.) of intermediate sward heights. The treatments consisted of five pre-grazing sward heights (10, 15, 20, 25, and 30 cm) randomly assigned to two of ten paddocks. The experimental design included two measurements of each paddock at different periods and times of day. Three Holstein heifers (440 ± 42 kg body weight) were used to determine the STIR, which was estimated using the double-weighing technique with correction for insensible weight losses. The bite mass (BM), bite rate (BR), sward structural characteristics, and nutritional value of herbage samples were assessed. The data were analyzed using mixed models with a factorial arrangement of five sward heights, two times of day, and two evaluation periods. The sward height of Kikuyu grass that maximized both STIRs was approximately 20 cm. The STIR of the DM was 30% and 15% lower than the maximum in the shortest and tallest swards tested, respectively. In swards shorter than 20 cm, the STIR was lower because the BM decreased with sward height, whereas in those greater than 20 cm, the lower BM and STIR of DM was explained by a decrease in bulk density and bite volume. The top stratum was composed mainly of highly digestible leaf blades with similar nutrient content across sward heights; therefore the STIR of digestible OM was also maximized at 20 cm. Hence, the optimal pre-grazing sward height of Kikuyu grass should be managed at 20 cm under rotational stocking systems to maximize nutrient intake rate of dairy heifers

Low-Intensity, High-Frequency Grazing Positively Affects Defoliating Behavior, Nutrient Intake and Blood Indicators of Nutrition and Stress in Sheep

The intensity and frequency of grazing affect the defoliating strategy of ruminants, their daily nutrient intake, thus nutrition and physiological status. Italian ryegrass (Lolium multiflorum Lam.) pastures were grazed by sheep either under a low-intensity/high-frequency grazing strategy (Rotatinuous stocking; RN) with nominal pre- and post-grazing sward heights of 18 and 11 cm, respectively, or under a high-intensity/low-frequency strategy (traditional rotational stocking; RT) with nominal pre- and post-grazing sward heights of 25 and 5 cm, respectively. Treatments were arranged under a complete randomized design and evaluated over two periods, in different years. In 2017, the aim was to depict the type of bites that sheep perform during the grazing-down and associate them to the grazing management strategy according to their relative contribution to the diet ingested. In 2018 we estimated the total nutrient intake and evaluated blood indicators of the nutritional status and immune response to stress of sheep. The bite types accounting the most for the diet ingested by RN sheep were those performed on the “top stratum” of plants with around 20, 15, and 25 cm, whereas the type of bites accounting the most for the diet of RT sheep were those performed on “grazed plants” with around 10, 5, and ≤ 3 cm. In 2018, the RN sheep increased by 18% the total organic matter (OM) intake and by 20–25% the intake of soluble nutrients (i.e., crude protein, total soluble sugars, crude fat), digestible OM and of metabolizable energy, and had 17.5, 18, and 6.1% greater blood concentration of glucose, urea nitrogen (BUN) and albumin, respectively, but 17% lower blood neutrophil-to-lymphocyte (N:L) ratio. Sheep grazing vegetative Italian ryegrass pastures under the low-intensity/high-frequency grazing strategy (RN) ingested a diet of better quality from bites allocated on the top stratum of plants, had greater intake of soluble nutrients and blood parameters positively associated with nutritional status and immune response to stress