Chemical and structural characterization of soil humic substances under agroforestry and conventional systems

Studies have proven that the agroforestry systems in the semi-arid region of the State of Ceará, Brazil, induce an increase in soil organic C levels. Notwithstanding, there is no information if this increase also results in qualitative changes in different pools of soil organic matter. The objective of this study was to verify the possible chemical and structural alterations in fulvic and humic acids of a Luvisol in areas adopting agroforestry, traditional intensive cultivation and native forest in a long-term experiment conducted in the semi-arid region of Ceará State, Brazil. The study was conducted in an experimental area of the National Goat Research Center (Embrapa) in Sobral, CE. The following treatments were evaluated: agrosilvopasture (AGP), silvopasture (SILV), intensive cultivation under fallow (ICF), and areas with native forest (NF). Soil fulvic and humic acids fractions were extracted from the 0-6 and 6-12 cm layers and characterized by elemental composition, thermogravimetry and infrared spectroscopy analyses. The elemental composition analysis of humic acids confirmed the data found for fulvic acids, showing reduction in the C, H and N levels, followed by an increase in O contents in the AGP and ICF treatments over SILV and NF. In all treatments, except to SILV in the 0-6 cm layer, the percentage of mass loss was highest (300-600 °C) for humic acids in the thermally most stable region. Despite the similarity between infrared spectra, soil fulvic acids in the SILV treatment extracted from 6-12 cm depth decrease the absorption bands at 1708 and 1408 cm-1 followed by an increase in the absorption band at 1608 cm-1 attributed to aromatic C=C groups. This behavior suggests an increase in the aromatic character of the structure. The AGP and ICF treatments, which increase the soil tilling, favored the maintenance of humic substances with a more aromatic character in the soil than SILV and NF. The less aromatic humic substances in the SILV treatment resulted in an increase of exchange sites of soil organic matter, indicating improved nutrient cycling and maintenance of productivity in the system.

Bioassay for detection of transgenic soybean seeds tolerant to glyphosate

Glyphosate is a systemic, nonselective, postemergence herbicide that inhibits growth of both weeds and crop plants. Once inside the plant, glyphosate interferes with biosynthesis of aromatic amino acids phenylalanine, tyrosine, and tryptophan, by inhibiting the activity of 5enolpyruvylshikimate-3-phosphate synthase (EPSPS), a key enzyme of the shikimate pathway. The objective of this work was to develop a simple, effective and inexpensible method for identification of transgenic soybean tolerant to glyphosate. This technique consisted in germinating soybean seeds in filter paper moistened with 100 to 200 muM of glyphosate. Transgenic soybean seeds tolerant to glyphosate germinated normally in this solution and, between 7 and 10 days, started to develop a primary root system. However non-transgenic seeds stopped primary root growth and emission of secondary roots.

Potential of antimicrobial volatile organic compounds to control Sclerotinia sclerotiorum in bean seeds

The objective of this work was to evaluate the potential of an artificial mixture of volatile organic compounds (VOCs), produced by Saccharomyces cerevisiae, to control Sclerotinia sclerotiorum in vitro and in bean seeds. The phytopathogenic fungus was exposed, in polystyrene plates, to an artificial atmosphere containing a mixture of six VOCs formed by alcohols (ethanol, 3-methyl-1-butanol, 2-methyl-1-butanol and phenylethyl alcohol) and esters (ethyl acetate and ethyl octanoate), in the proportions found in the atmosphere naturally produced by yeast. Bean seeds artificially contamined with the pathogen were fumigated with the mixture of VOCs in sealed glass flasks for four and seven days. In the in vitro assays, the compounds 2-methyl-1-butanol and 3-methyl-1-butanol were the most active against S. sclerotiorum, completely inhibiting its mycelial growth at 0.8 µL mL-1, followed by the ethyl acetate, at 1.2 µL mL-1. Bean seeds fumigated with the VOCs at 3.5 µL mL-1 showed a 75% reduction in S. sclerotiorum incidence after four days of fumigation. The VOCs produced by S. cerevisiae have potential to control the pathogen in stored seeds.

Molecular and morphological characterization of hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose

The objective of this work was to characterize the morphology and molecular composition of the hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose. The produced hydrochar consists mainly of aggregate microspheres with about 2.0 µm in diameter, with aliphatic and aromatic structures and the presence of carbonyl functional groups. The aromatic groups are formed mainly by benzofuran-like structures, being chemically different from common cellulose char. Microwave-assisted hydrothermal carbonization yields a functionalized carbon-rich material similar to that produced by the conventional hydrothermal process.

Reproducing the organic matter model of anthropogenic dark earth of Amazonia and testing the ecotoxicity of functionalized charcoal compounds

The objective of this work was to obtain organic compounds similar to the ones found in the organic matter of anthropogenic dark earth of Amazonia (ADE) using a chemical functionalization procedure on activated charcoal, as well as to determine their ecotoxicity. Based on the study of the organic matter from ADE, an organic model was proposed and an attempt to reproduce it was described. Activated charcoal was oxidized with the use of sodium hypochlorite at different concentrations. Nuclear magnetic resonance was performed to verify if the spectra of the obtained products were similar to the ones of humic acids from ADE. The similarity between spectra indicated that the obtained products were polycondensed aromatic structures with carboxyl groups: a soil amendment that can contribute to soil fertility and to its sustainable use. An ecotoxicological test with Daphnia similis was performed on the more soluble fraction (fulvic acids) of the produced soil amendment. Aryl chloride was formed during the synthesis of the organic compounds from activated charcoal functionalization and partially removed through a purification process. However, it is probable that some aryl chloride remained in the final product, since the ecotoxicological test indicated that the chemical functionalized soil amendment is moderately toxic.

Evolutionary steps in the reproductive biology of Annonaceae

Flowers of Annonaceae are characterized by fleshy petals, many stamens with hard connective shields and numerous carpels with sessile stigmas often covered by sticky secretions. The petals of many representatives during anthesis form a closed pollination chamber. Protogynous dichogamy with strong scent emissions especially during the pistillate stage is a character of nearly all species. Scent emissions can be enhanced by thermogenesis. The prevailing reproductive system in the family seems to be self-compatibility. The basal genus Anaxagorea besides exhibiting several ancestral morphological characters has also many characters which reappear in other genera. Strong fruit-like scents consisting of fruit-esters and alcohols mainly attract small fruit-beetles (genus Colopterus, Nitidulidae) as pollinators, as well as several other beetles (Curculionidae, Chrysomelidae) and fruit-flies (Drosophilidae), which themselves gnaw on the thick petals or their larvae are petal or ovule predators. The flowers and the thick petals are thus a floral brood substrate for the visitors and the thick petals of Anaxagorea have to be interpreted as an antipredator structure. Another function of the closed thick petals is the production of heat by accumulated starch, which enhances scent emission and provides a warm shelter for the attracted beetles. Insight into floral characters and floral ecology of Anaxagorea, the sister group of the rest of the Annonaceae, is particularly important for understanding functional evolution and diversification of the family as a whole. As beetle pollination (cantharophily) is plesiomorphic in Anaxagorea and in Annonaceae, characters associated with beetle pollination appear imprinted in members of the whole family. Pollination by beetles (cantharophily) is the predominant mode of the majority of species worldwide. Examples are given of diurnal representatives (e.g., Guatteria, Duguetia, Annona) which function on the basis of fruit-imitating flowers attracting mainly fruit-inhabiting nitidulid beetles, as well as nocturnal species (e.g., large-flowered Annona and Duguetia species), which additionally to most of the diurnal species exhibit strong flower warming and provide very thick petal tissues for the voracious dynastid scarab beetles (Dynastinae, Scarabaeidae). Further examples will show that a few Annonaceae have adapted in their pollination also to thrips, flies, cockroaches and even bees. Although this non-beetle pollinated species have adapted in flower structure and scent compounds to their respective insects, they still retain some of the specialized cantharophilous characters of their ancestors.

Reações de Etanol com CO/H2 na Presença do Sistema Catalítico Ru(acac)3/I-

The hydrocarbonylation reaction of ethanol with a CO/H2 mixture assisted by Ru(acac)3/iodide was investigated. Bronsted and Lewis acids and iodides salt were used as homogeneous promoters. The etherification reaction was the main reaction under typical acidic conditions of the catalytic system. When a hydrocarbon solvent (toluene) was added to the initial reaction, the alcohol conversion and the carbonylation products were increased. The catalytic activity of the Bronsted acids (conv. EtOH = 71-92%) was higher than that of the Lewis acids promoters (conv. EtOH = 65-85%). The salt present the lower catalytic activity among the promoters used. The long time reaction carried out with ethanol showed an increase of the product selectivity of the homologation and carbonylation reactions while the etherification reaction selectivity decreased. The recycled ether led to 60-65% ethanol conversion to C5 and C6 products. The main catalytic species are H+[Ru(CO)3I3]-, [HRu3(CO)11]- and [HRu(CO)4]-. The first one is active in the carbonylation and homologation reactions of alcohols while the two others take part only in the homologation reaction.

Alcatrão ou creosoto de eucalipto na produção de adesivos fenólicos para colagem de madeira

This study has shown that Eucalyptus tar and creosote can be used in phenolic adhesive formulations (resols) for wood products bonding. Some adhesives were prepared substituting 0; 17.7; 35.0 and 67.0% of the phenol by anhydrous tar and 0; 15.0 e 28.5% by creosote. In gluing Brazilian pine veneers, eucalypt tar and creosote based adhesives required longer pressing times for curing than conventional phenol-formaldehyde adhesives. By using 13C NMR, the number of carbons in side chains and hydroxyl, carbonyl, carboxyl and methoxyl groups related to 100 aromatic rings could be estimated in tar and creosote. In creosote, after reaction with excess formaldehyde in alkaline medium, only 0,28 hydroxymethyl groups was detected per phenolic ring. This low amount of hydroxymethylation explains the lack of reactivity in curing observed when creosote was introduced in a standard adhesive formulation.

Organo-gel: um novo sistema para a imobilização de lipases e sua aplicação em síntese orgânica

Lipases have been immobilized in microemulsion-based organogels (MBG's) and successfully utilized for the enantioselective esterification, diesterification and transesterification reactions, in organic solvents at 25ºC. This methodology is described as a new alternative for the use of enzymes in organic solvents. High enzymic stability has been observed. We have also used this methodology for the successful resolution of chiral secondary alcohols. This is a convenient way of using this catalyst in organic solvents which employs small amounts of the enzyme (250mg/mL).

Decomposição catalítica de óleo de soja em presença de diferentes zeólitas

The catalytic decomposition of soybean oil was studied in a fix bed reactor at 673 and 773 K and using amorphous silica-alumina and the zeolites USY, H-Mordenite and H-ZSM-5 as catalysts. Both the selectivity and the catalytic activity were determined by studying the product composition resulting from the chemical reactions. Physicochemical characteristics of the catalysts were obtained by X-ray fluorescence, Fourier Transform infrared spectroscopy, 29Si and 27Al Nuclear Magnetic Ressonance and textural analysis. The zeolites USY and H-ZSM-5, showing higher Brönsted acidity, yielded products with higher concentration in aromatic hydrocarbons, whereas with both H-Mordenite and amorphous silica-alumina the main products were paraffins.

Oxidações eletrocatalíticas de álcoois e dióis em meio bifásico utilizando metanossulfonato de CeIV como mediador

Some alcohols and diols were oxidized electrocatalytically in a biphasic system using ceriumIV methanesulphonate as mediator. A mixture of methanesulphonic acid solution and benzene was used and aldehydes, ketones and diacids were some of the principal products obtained with yield varying from 27 to 98%. In several cases selectivity was obtained.

Influência do material do alambique na composição química das aguardentes de cana-de-açúcar

This paper describes variations in the profile of the main volatile organic compounds present in Brazilian sugar cane spirits distilled in copper and stainless steel distillers. The main organic compounds: aldehydes, ketones, carboxylic acids, alcohols and esters, were determined through High Performance Liquid Chromatography (HPLC) and High Resolution Gas Cromatography (HRGC). The spirits produced in copper distillers exhibit higher contents of aldehydes with respect to the ones produced in stainless steel. The inverse is true with respect to the higher alcohol and ester contents. No significant variation has been observed for the carboxylic acids.

Estudo calorimétrico da interação de álcoois com Saccharomyces cerevisiae a 298 K

The calorimetric experiments based on technique breaking ampoule were carried out by measuring of the heat of solution of alcohol in isotonic solution (NaCl 0.10 M) and alcohol in suspension of Sc at 298 K. From these data the enthalpy of interaction alcohol with suspension of Sc (DtrsH°) was calculate by Hess law. In this study, the results indicate that the enthalpy of interaction of aliphatic alcohol (C2-C8) with suspensions of Sc is a process exothermic and becomes more exothermic with increasing of -CH2 group of alcohol in range -1,14 to -4,0 kJ.mol-1. We concluded that enthalpy of interaction shows a linear relationship with increasing of alcohol's lipophilicity, in agreement with Traube's rule.

Wilhelm Michler, uma aventura científica nos trópicos

Wilhelm Michler lived in Brazil for seven years from 1882 to 1889, when he died. Here, he published several articles on natural products, and became a professor of Industrial Chemistry at the Escola Politécnica, in Rio de Janeiro. He was respected by colleagues and students. This article addresses this poorly known period of the life of a scientist, world-famous by the aromatic ketone that carries his name.

Synthesis of 2-(alkylamino)-1-phenylethane-1-thiosulfuric acids, potential schistosomicides

The total synthesis of seven here-to-fore unreported aromatic aminoalkanethiosulfuric acids, their physical properties and those of the aminoalcohol and bromoalkanamine intermediates are reported. All structures were established by including ¹H and 13C NMR, IR and MS spectroscopy and elemental analysis.