In this work, an iron/biochar composite was evaluated as a catalyst for 3,6-dichloro-2-methoxybenzoic acid (dicamba) herbicide degradation by heterogeneous Fenton-like process. The biochar was produced from pyrolysis of coffee husks. After FeII adsorption by biochar, the material was submitted to chemical reduction, via borohydride, producing zero-valent iron nanoparticles (BIO-Fe0). The material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and energy dispersive X-ray spectroscopy, Raman scattering spectroscopy, nitrogen adsorption/desorption analysis, among other techniques. The BIO-Fe0 is a heterogeneous material, and the main constituent elements are carbon (C), oxygen (O), silicon (Si), sulfur (S) and iron (Fe). The dicamba degradation was monitored by high-performance liquid chromatography and biological assays using beans (Phaseolus vulgaris) as indicator species. The commercial dicamba (500 mL; 250 mg L 1) was submitted to Fenton-like process (initial pH 3.20; BIO-Fe0: 3 or 5 g; 1.00 mL H2O2 at 3.00 mmol L 1; 1.00 mL Al2(SO4)3 at 1.00 mol L 1; 25 ºC and 5 h of reaction), presenting ca. 100% of degradation. These treated solutions were used in a biological assay. The intoxication levels were less 30%. These results show that BIO-Fe0 has the potential to be used in the dicamba degradation by Fenton-like processes.

Abstract Background The study of corn and palisade grass physiology may assist in determining the best arrangement of the plants and more efficient management of this intercropped system. Objective To evaluate the effects of different palisade grass plant arrangements and their control on physiological characteristics and corn yield. Methods Two trials in randomized complete block design with four replications were conducted in field conditions. In the first, corn was sown with 0.50 m row spacing, whereas the second had 1.00 m row spacing. All the treatments were arranged in the same way in both experiments, in a 2x4 factorial design. The first factor was the nicosulfuron dose applied (0 and 8 g a.i. ha-1), and the second, the forage seeding rates (0, 2, 4, and 6 kg of seeds per hectare). Sowing of both species was performed on the same day. Results The application of nicosulfuron negatively affected stomatal conductance, internal carbon concentration, and increased CO2 consumption and efficiency in water use. The photosynthetic rate was not affected by the herbicide application, however it presented lower values in the 0.50 m spacing. Although the yield was not affected by row spacing, it was higher when nicosulfuron was applied. Conclusions The increase in palisade grass density caused detrimental changes in the water use efficiency with direct consequences to the crop yield. The physiological response and corn yield depend on the arrangement of plants and the palisade grass management adopted.

Abstract Background: Studies of sorption and desorption of herbicides in soils are essential in predicting their transport, bioavailability, and transformation in the soil profile. These studies are also vital to predict the agronomic efficiency of the herbicides in controlling weeds. Objective: In this study, atrazine’s sorption and desorption kinetics were evaluated in samples composed of single and a mixture of horizons from the Red-Yellow Latosol profile. Methods: This was performed by the Batch equilibrium method, and the quantification was carried out using a High-performance liquid chromatography (HPLC). Results: Freundlich isotherms were adjusted appropriately to describe the atrazine sorption. The Kf values obtained varied between 0.188 and 2.592, and the Koc values ranged between 37.76 and 143.81, which corresponded to horizons C and A, respectively. The desorption was only possible to determine in horizon A. The other substrates presented low sorption, and the desorption of the remaining atrazine was not significant, therefore not adjusting to the Freundlich model. The organic matter (OM) was the main attribute to the atrazine sorption in the soil, presenting a high correlation with Kf and Koc values. In the horizon A samples, the Kfd value obtained in desorption was higher than the Kf obtained in sorption, which indicated a low desorption capacity and, therefore, low potential mobility of the herbicide in this soil horizon. Conclusions: It was concluded that the organic matter present in greater quantity in horizon A of the Red-Yellow Latosol has a crucial role in the dynamics of atrazine in the horizons of this soil.

Chemotherapy treatment of leishmaniasis is based on the use of pentavalent antimonials, but these drugs present low efficacy and high toxicity. In the search for new antileishmanial agents, essential oils (EOs) from four Croton species (C. argyrophylloides, C. jacobinensis, C. nepetifolius and C. sincorensis) were evaluated against Leishmania infantum chagasi, L. amazonensis and L. braziliensis. EOs were analyzed by gas chromatography combined with mass spectrometry. Spathulenol, β-caryophyllene, β-caryophyllene oxide, 1,8-cineole and methyl eugenol were the major constituents. The evaluation of antioxidant activity by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) method showed that all EOs have moderate antioxidant activity. All oils were similarly active against L. i. chagasi, and C. nepetifolius EO showed the best result against L. amazonensis, with median inhibitory concentrations (IC50) of 9.87 μg mL-1, similar to amphotericin B (IC50 = 7.38 μg mL-1). The oils presented low cytotoxicity in macrophages. The in silico analysis revealed that spathulenol and 1,8-cineole were active against the enzyme Leishmania infantum trypanothione reductase (LiTR), showing excellent interaction energies, making them promising agents for leishmaniasis control.

In this work, a new and sensitive electroanalytical methodology was developed and validated to quantify sulfentrazone in soil samples. Sulfentrazone was initially characterized qualitatively using cyclic voltammetry (CV). Its oxidation occurred by diffusion (mass transport) on a glassy carbon electrode (GCE) via irreversible transfer of one electron close to a peak potential of +0.936 V vs. Ag|AgCl, 3.0 mol L-1 KCl, in 0.10 mol L-1 KOH. Differential-pulse voltammetry (DPV) was the most sensitive and selective technique, with limits of detection (LOD) of 1.94 and 2.19 mmol L-1 and limits of quantification (LOQ) of 6.46 and 7.31 mmol L-1, in the absence and presence of soil matrix, respectively. The reproducibility of the method ranged between 2.65 and 4.2%, with intermediate precision between 5.32 and 10.9%. The recovery rate ranged between 88.5 and 103%. Additionally, the accuracy of the electroanalytical method was validated by comparing the results with data from a standard analytical methodology of high-performance liquid chromatography (HPLC/UV-Vis).

The mechanical behavior of the API 5L X60 and X80 grade steels under environmental hydrogen embrittlement effect and internal hydrogen embrittlement effect was determined. The potential and current density for hydrogen generation were determined by potentiodynamic polarization. The saturation time was estimated from diffusivity and solubility data, obtained from permeation tests with an electrochemical cell. The hydrogen charge to reproduce the conditions of the environmental hydrogen embrittlement and the internal hydrogen embrittlement was performed by generating a concentration gradient in the first case, and a concentration and stress gradients in the second case. After the tensile tests it was verified that in the defined tests conditions, the fracture mode in both types of embrittlement was predominantly ductile. Also, both steels showed low or moderate susceptibility to environmental hydrogen embrittlement, not being susceptible to internal hydrogen embrittlement.

Se ha determinado el comportamiento mecánico de los aceros API 5L grados X60 y X80, fragilizados por hidrógeno ambiental y por hidrógeno interno. El potencial y la densidad de corriente para la generación del hidrógeno fueron determinados por polarización potenciodinámica, y el tiempo de saturación estimado a partir de datos de difusividad y solubilidad obtenidos en ensayos de permeación con una célula electroquímica. La carga de hidrógeno para reproducir las condiciones de la fragilización por hidrógeno ambiental y fragilización por hidrógeno interno fue realizada generando un gradiente de concentración para el primer caso, y generando gradientes de concentración y de tensiones para el segundo. Luego de los ensayos de tracción se verificò que, en las condiciones definidas en este trabajo, el modo de fractura en ambos tipos de fragilización fue predominantemente dúctil. Ademàs, los dos aceros mostraron una susceptibilidad baja o moderada a la fragilización por hidrógeno ambiental, no siendo susceptibles a la fragilización por hidrógeno interno.

A numeric formulation is presented based on a combination of fracture mechanics and continuum damage mechanics to treat the problem of the crack propagation in elastic regime, under the effect of a mechanical action defined by a static load applied in the tensile mode and of an environmental action characterized by hydrogen diffusion into the lattice. The equations that describe the evolution of the variables at the crack tip form a non-linear system of ordinary differential equations that is solved using the 4th order Runge-Kutta method. The results show the influence of hydrogen on the decrease of the time at which cracks starts and propagates, which is consistent with macroscopic observations of the hydrogen embrittlement phenomenon.

Se presenta una formulación numérica basada en una combinación de la mecánica de la fractura y de la mecánica del daño continuo para tratar el problema de la propagación de una fisura en régimen elástico, bajo el efecto de una acción mecánica definida por una carga estática aplicada en el modo de fractura I y de una acción ambiental caracterizada por la difusión de hidrógeno a través de la estructura cristalina del material. Las ecuaciones que describen la evolución de las variables en la punta de la fisura forman un sistema no lineal de ecuaciones diferenciales ordinarias que es resuelto con el método de Runge-Kutta de 4º orden. Los resultados obtenidos muestran la influencia del hidrógeno en la disminución del tiempo de inicio y propagación de fisuras, lo que es consistente con las observaciones macroscópicas del fenómeno de fragilización por hidrógeno.

The root exudates produced by sorghum contain a biologically active constituent known as sorgoleone. The behavior of sorgoleone in a Red-Yellow Latosol was studied. The sorption model of sorgoleone in soil was better adjusted to the Freundlich equation, through the coefficients Kf (capacity of sorption) and 1/n (linearity of the isotherm). The persistence of sorgoleone in soil and its possible degradation were also evaluated by monitoring their residues in the soil along the time. Recovery rate of sorgoleone from the soil reached 93% after 24h. It was verified that sorgoleone is strongly sorbed in the soil and its half-life is 10 days, under the experimental conditions. The presence of sorgoleone or its metabolites was not detected in the soil after 60 days.

Durante o ano agrícola 1994/95, foi conduzido ensaio de campo, em Capinópolis, MG, visando avaliar o efeito residua l no solo dos herbicidas imazamox (50 e 100 g/ha) e imazethapyr (100 e 200 g/ha), aplicados à cultura da soja, sobre as culturas de milho e sorgo, cultiva das em sistema de sucessão à soja. Foram realizados, em casa de vegetação, bioensaios utilizando o sorgo como planta - teste, em amostras de solo coletadas nas parcelas onde foram aplicados os herbicidas no campo. As amostras de solo foram coletadas aos 30, 60, 90 e 120 dias após a aplicação (DAA) dos herbicidas. Um dia após a colheita da soja, fez-se também a semeadura, no campo, do milho e do sorgo nas parcelas anteriormente ocupadas com a soja, onde haviam sido feitas as aplicações dos herbicidas. Os resultados obtidos indicam que o imazamox apresentou menor efeito residual, não influenciando no desenvolvimento da planta-teste quando esta foi semeada aos 120 DAA, até mesmo no dobro da dose recomendada. Todavia, o imazethapyr a 200 g/ha (dobro da dose recomendada) apresentou inibição no desenvolvimento das plantas de sorgo quando estas foram semeadas 120 DAA. Em condições de campo, plantas de sorgo semeadas após a colheita da soja em áreas que receberam o dobro da dose recomendada de imazethapyr evidenciaram menor altura de plantas e menor comprimento de panícula do sorgo, não influenciando, entretanto, a produtividade de grãos.

During the 1994/95 growing season, a field assay was conducted in Capinópolis, MG, to evaluate the carryover effect of the herbicides imazamox (50 and 100 g/ha), and imazethapyr (100 and 200 g/ha), applied in soybean, to corn and sorghum crops succeeding soybean. Bioassays using sorghum as test-plant were conducted in greenhouse conditions using soil samples collected from plots sprayed with the herbicides in field. Soil samples were collected at 30, 60, 90 and 120 days after application (DAA) of herbicides. One day after soybean harvest, corn and sorghum were also sowed in the field plots previously used for soybean growth, where the herbicides had been applied. The results obtained denote that imazamox had a shorter residual effect in soil, having no influence on the development of the test-plan t at 120 DAA, even when at double the recommended rate. However, imazethapyr appl ied at 200 g/ha (double the recommended rate), inhibited the development of sorghum plants sowed 120 DAA. Under field conditions, sorghum plants sowed after soybean harvest in areas receiving double the recommended rate of imazethapyr evidenced shorter plant height and shorter plant panicle, although having no effect on grain productivity.

Estudou-se, em Ribeirão Preto, SP, Brasil, no período de 1º de junho de 1978 a 31 de maio de 1979, 98% do universo de nascidos vivos, totalizando 8.878 crianças nascidas de parto único. As taxas de baixo peso e de peso deficiente ao nascer foram de 7,5% e de 21,1%, respectivamente. A maioria dos nascimentos de baixo peso eram crianças a termo, 50,6%, representando casos de retardo de crescimento intra-uterino. A prevalência de baixo peso nas classes sociais foi de 3,2% na burguesia empresarial, 2,8% na burguesia gerencial, 3,9% na pequena burguesia, 7,0% no proletariado e 9,5% no subproletariado, o que demonstra uma profunda disparidade. Definindo-se o baixo peso como menor ou igual a 2.500 gramas e comparando os resultados alcançados (8,3%) com os de outro estudo clássico (8,7%), observou-se que não houve redução estatisticamente significativa na prevalência de baixo peso em Ribeirão Preto, no intervalo de uma década.

A survey was carried out in Ribeirão Preto, S. Paulo State, Brazil, between June 1978 and May 1979 with a view to studying the prevalence of low birth weight and its occurrence among different social classes. Data were collected from 8,878 singleton live births in eight maternity hospitals, accounting for 98% of all births in the area. Social classes were determinated by the use of a model proposed by Singer and modified for epidemiological purposes by Barros. Out of the 8,878 births, 660 (7.5%) were of low birth weight. The prevalence of deficient weight at birth (between 2,500 and 2,999 grams) was of 21.1%. Analysis indicated that 50.6% of children with low birth weight were at term and the majority of them suffered form intrauterine growth retardation. The prevalence of low birth weight according to social class was seen to be lower in the bourgeoisie classes (ranging from 2.8% to 3.9%) and higher in working classes (from 7% up to 9.5%). Low birth weight (defined as < 2,500 grams) was used for purposes of comparison with other previous surveys. The percentage was lower in this study (8.3%) than that found in the Interamerican Investigation of Mortality in Childhood (8.7%), carried out in 1968-70. No statistically significant differences in the percentage of low birth weight were found in the case of Ribeirão Preto when these two surveys were compared.

Estudou-se, em Ribeirão Preto, SP, Brasil, no período de 1º de junho de 1978 a 31 de maio de 1979, 98% do universo de nascidos vivos, totalizando 8.878 crianças nascidas de parto único. As taxas de baixo peso e de peso deficiente ao nascer foram de 7,5% e de 21,1%, respectivamente. A maioria dos nascimentos de baixo peso eram crianças a termo, 50,6%, representando casos de retardo de crescimento intra-uterino. A prevalência de baixo peso nas classes sociais foi de 3,2% na burguesia empresarial, 2,8% na burguesia gerencial, 3,9% na pequena burguesia, 7,0% no proletariado e 9,5% no subproletariado, o que demonstra uma profunda disparidade. Definindo-se o baixo peso como menor ou igual a 2.500 gramas e comparando os resultados alcançados (8,3%) com os de outro estudo clássico (8,7%), observou-se que não houve redução estatisticamente significativa na prevalência de baixo peso em Ribeirão Preto, no intervalo de uma década.

A survey was carried out in Ribeirão Preto, S. Paulo State, Brazil, between June 1978 and May 1979 with a view to studying the prevalence of low birth weight and its occurrence among different social classes. Data were collected from 8,878 singleton live births in eight maternity hospitals, accounting for 98% of all births in the area. Social classes were determinated by the use of a model proposed by Singer and modified for epidemiological purposes by Barros. Out of the 8,878 births, 660 (7.5%) were of low birth weight. The prevalence of deficient weight at birth (between 2,500 and 2,999 grams) was of 21.1%. Analysis indicated that 50.6% of children with low birth weight were at term and the majority of them suffered form intrauterine growth retardation. The prevalence of low birth weight according to social class was seen to be lower in the bourgeoisie classes (ranging from 2.8% to 3.9%) and higher in working classes (from 7% up to 9.5%). Low birth weight (defined as < 2,500 grams) was used for purposes of comparison with other previous surveys. The percentage was lower in this study (8.3%) than that found in the Interamerican Investigation of Mortality in Childhood (8.7%), carried out in 1968-70. No statistically significant differences in the percentage of low birth weight were found in the case of Ribeirão Preto when these two surveys were compared.

Este ensaio foi realizado com o objetivo de estudar os efeitos de estimulantes vegetais no desenvolvimento do feijoeiro 'Goiano Precoce', em condições de casa de vegetaçio. Pix (cloreto de mepiquat), Atonik (mononitroguaiacolsódico + compostos nitroaromáticos), Ergostim (AATC + ácido fólico) e Cytozyme (citocinina + derivados de etoxilato-siloxano + outros compostos) foram aplicados, 30 dias após a semeadura, nas dosagens de 1,0; 1,0; 0,5 e 2,0 l/ha, respectivamente. Verificou-se que Ergostim causou maior crescimento e apresentou uma tendência de aumentar o número de vagens e sementes, tendo reduzido a relação K/r. Pix mostrou uma tendência de aumentar o número de vagens, a relação K/r e o teor de proteína nas sementes. Atonik e Cytozyme não provocaram modificações nos parâmetros estudados.

This research deals with the effects of Pix, Atonik, Ergostim and Cytozyme application on behavior of beans (Phaseolus vulgaris L. cv. Goiano Precoce), under greenhouse conditions. Beans were sowing in pots and Pix and Atonik (1.0 l/ha), Ergostim (0.5 l/ha) and Cytozyme (2.0 l/ha) were applied 30 days after sowing. Ergostim promoted growth and presented a tendency to increase number of pods and seeds, and reduced K/r ratio. Pix presented a tendency to increase number of pods, K/r ratio and protein level in the seeds. Atonik and Cytozyme did not promote changes in the parameters studied.