ABSTRACT The objectives were to evaluate the effects of monensin and virginiamycin, alone or combined, on supplemented Nellore cattle grazing tropical grass during the rainy season. Two experiments were conducted simultaneously to evaluate intake, digestibility, CH4 emissions, blood parameters, performance, and carcass characteristics (Exp. 1), and ruminal fermentation and relative abundance of ruminal microorganisms (Exp. 2). Animals (n = 92 Exp. 1 and n = 12 Exp. 2) were distributed in a completely randomized design and allocated in twelve paddocks composed of Urochloa brizantha (A. Rich.) Stapf. cv. Xaraés. A protein-energetic supplementation of 3 g/kg of BW per day was provided to all animals. Supplements were: without additives (WA), monensin alone at 80 mg/kg of product (MN), virginiamycin alone at 150 mg/kg of product (VM), and monensin (80 mg/kg of product) combined with virginiamycin (150 mg/kg of product; MNVM). Treatments did not affect intakes of total dry matter (DM), supplement DM, and nutrients. However, the intakes of forage DM and crude protein decreased in cattle fed MNVM compared with animals fed WA, MN, and VM. Total volatile fatty acids increased in animals fed VM. Ruminal NH3-N decreased, and pH increased in animals fed MN, VM, and MNVM. Relative abundance of total F. succinogenes and S. ruminantium decreased and R. flavefaciens increased in animals fed MN and VM at d 118. Treatments had no effect on enteric CH4 emissions. The average daily gain (ADG) and total gain were greater in cattle fed MNVM than in cattle fed MN. Combination of monensin and virginiamycin altered the rumen microbial populations but did not decrease enteric CH4 emissions. However, it decreased forage dry matter intake without altering the ADG and total weight gain, leading to an increase in feed efficiency. Results from this study indicate an advantage in including feed additives combined in the diet of supplemented Nellore cattle grazing tropical grass during the rainy season.

Abstract Background Species of Amaranthus genus are common in agricultural areas of Brazil. Such weeds are problematic, and they bring complexity to the management mainly due to herbicide resistance. Thus, the monitoring and mapping of chlorimuron-resistant Amaranthus spp. is necessary to detect resistance in different locations of Brazil. Objective Elaborate discriminating dose of distinction between Amaranthus spp. populations that are susceptible and resistant to chlorimuron and monitor the resistance dispersal throughout five crops. Methods 33 pigweed populations from the main grain producing properties in Brazil by means of dose-response curves were evaluated. For the D dose, chlorimuron dose of 20 g ha-1 ai was considered. Once the discriminating dose was identified, a monitoring screening of the dispersal of resistance of Amaranthus spp. to chlorimuron was conducted with 226 samples between the 2016 and 2020 crops. Results The discriminating dose (“base line”) considered ideal to control susceptible plants was 20 g ha-1 of chlorimuron. Among 226 pigweed samples evaluated in the five years of monitoring, 74% of populations were considered susceptible (S), while those classified as resistant (R) and segregating (r) did not exceed 26.0%. Conclusions By comparing susceptible biotypes of Amaranthus spp. with international scientific literature standards and leaflet averages, it could be safely concluded that the discriminating dose of chlorimuron is 20 g ha-1. Resistance of Amaranthus spp. to chlorimuron in Brazil is present in the main soybean producing regions evaluated, with a frequency of 26% of the total samples evaluated.

Este estudo trata do efeito do enxofre no silicato de dicálcio (Ca2SiO4), uma fase cristalina majoritária (20 a 40 peso%) do clínquer do cimento Portland comum. O silicato de dicálcio é também conhecido como C2S (2CaO.SiO2) ou belita. A síntese de amostras de C2S foi feita a partir de reagentes de alta pureza com adição de enxofre como CaSO4.2H2O, misturados na proporção estequiométrica 2Ca:(1-x)Si:xS, na qual x corresponde à proporção catiônica de enxofre, com valores de 0 a 20%. Os teores adicionados de SO3 nas amostras foram 0,23, 1,39, 2,77, 4,60 e 9,71 peso%. A composição química das amostras foi determinada por meio de fluorescência de raios X antes e após sinterização. A perda por volatilização em alta escala de enxofre levou a um excesso de cálcio e conseqüentemente à formação crescente de silicato de tricálcio com aumento crescente de enxofre na mistura inicial. A composição mineralógica das amostras e os parâmetros de rede dos polimorfos de C2S foram determinados por difração de raios X e refinamento de Rietveld. A análise estrutural dos resultados de difração indica que a presença de enxofre estabiliza a forma de temperatura intermediária β C2S, com aumento crescente do volume da célula unitária. A reatividade com água (calor de hidratação) das amostras foi medido por calorimetria diferencial de varredura, que foi fortemente influenciado pela alta reatividade do silicato de tricálcio.

The present study regards the effect of sulfur in dicalcium silicate (Ca2SiO4), a major crystalline phase (20 to 40 wt.%) of the ordinary Portland cement clinker. Dicalcium silicate is also known as C2S (2CaO.SiO2) or belite. The synthesis of the C2S samples was made with high purity reactants with addition of sulfur as CaSO4.2H2O, mixed according to the stoichiometric proportion 2Ca:(1-x)Si:xS, in which x corresponds to the cationic proportion of sulfur, with values ranging from 0 to 20%. Added amounts of SO3 in the samples were 0.23, 1.39, 2.77, 4.60 and 9.71wt.%. Chemical composition of the samples was determined by X-ray fluorescence before and after sintering. Large-scale sulfur loss by volatilization leads to an excess in calcium and consequently to formation of increasing amounts of tricalcium silicate with increasing sulfur content in the starting mixture. Mineralogical composition of the samples and cell parameters of C2S polymorphs were determined by X-ray diffraction and Rietveld refinements. Structural analysis of diffraction data indicates that the presence of sulfur stabilizes the intermediate temperature polymorph β C2S, with increasing unit cell volume. The reactivity with water (heat of hydration) of the samples was measured by differential scanning calorimetry, which was strongly influenced by the highly reactive tricalcium silicate.

Duas séries de clínqueres experimentais foram sintetizadas com matérias-primas contendo rejeitos da mineração de basalto para a produção de agregados para concreto. Os clínqueres experimentais foram produzidos a partir de uma farinha crua padrão com adições de teores variáveis de materiais basálticos, sendo que o fator de saturação em cal e os módulos de sílica e alumina da farinha crua foram mantidos constantes pelo ajuste das proporções de calcário, argila e minério de ferro em relação ao teor de material basáltico adicionado. Uma das séries de clínqueres foi produzida com finos de pedreira, usados em parte como agregados finos, mas também acumulados como pilhas de rejeitos no pátio da mina. A outra série foi feita com basalto vesicular, uma variedade de basalto poroso e de baixa resistência, não aproveitada como agregado. O estudo revela que a composição dos materiais basálticos é plenamente compatível com a produção de clínquer, não sendo necessária a adição de fundentes ou outros corretivos químicos. A composição dos clínqueres experimentais produzidos foi determinada por análises químicas, por análise quantitativa de fases em microscopia óptica (contagem de pontos) e por difratometria de raios X. Os clínqueres experimentais produzidos a partir de farinhas contendo materiais basálticos são similares aos clínqueres industriais convencionais, em termos de composição química e de proporção entre fases cristalinas.

Large volumes of waste materials are produced by crushing of basaltic rocks for aggregate production, which is widely used in regions that lack rocks of granitic or gneissic composition. Two types of waste materials are produced (a) quarry fines, which are in part used as fine aggregates in concrete and (b) vesicular basalt, a porous variety of basalt that is useless as aggregate. This paper presents a procedure to use basaltic mine-tailings as raw-mixtures for Portland cement by adjusting the proportion of the other raw-materials (limestone, clay, iron ore). It is demonstrated that there is no need for additional fluxes to the basalt-bearing raw-mixtures, since the setting of the chemical parameters is enough to guarantee clinker formation. Two series of experimental clinkers were synthesized with raw-mixtures containing residues from a basalt quarry that produces aggregates for concrete. Experimental clinkers were produced from raw-mixtures with similar lime saturation factors, silica and alumina modules, which were set by adjusting the proportions of limestone, clay and iron ore to the varying proportions of basaltic materials added to them. One series of clinkers was made with basalt quarry fines, which are in part used as fine aggregate, but also accumulate as mine-tailings. Other series was made using vesicular (porous) basalt, a variety not resistant enough to be used as aggregate. It is demonstrated that the basaltic composition is fully compatible with clinker production, and no addition of fluxes or other additions is required. Composition of the raw-mixtures was checked by chemical analysis. Quantitative phase analysis of the clinkers was made by optical microscopy point counting, together with qualitative X-ray diffraction. All mixtures produced clinkers with acceptable proportions of major and minor crystalline phases, inside the range of common industrial Portland clinkers.