Biomarkers for the assessment of chlorpyrifos effects on earthworms and on soil functional parameters

The objective of this work was to evaluate the effects of chlorpyrifos on earthworms and on soil functional parameters. An integrated laboratory-field study was performed in a wheat field in Argentina, sprayed with chlorpyrifos at two recommended application rates (240 or 960 g ha-1 style='vertical-align:baseline'> a.i.). Laboratory tests included neutral red retention time, comet assay (single cell gel electrophoresis), and avoidance behavior, each using the earthworm Eisenia andrei exposed in soil collected 1 or 14 days after pesticide application, and the bait-lamina test. Field tests assessed organic matter breakdown using the litterbag and bait-lamina assays. Earthworm populations in the field were assessed using formalin application and hand-sorting. The neutral red retention time and comet assays were sensitive biomarkers to the effects of chlorpyrifos on the earthworm E. andrei; however, the earthworm avoidance test was not sufficiently robust to assess these effects. Feeding activity of soil biota, assessed by the bait lamina test, was significantly inhibited by chlorpyrifos after 97 days, but recovered by the 118th day of the test. Litterbag test showed no significant differences in comparison to controls. Earthworm abundance in the field was too low to adequately test the sensitivity of this assessment endpoint.

Hot spots for diversity of Magnaporthe oryzae physiological races in irrigated rice fields in Brazil

The objective of this work was to evaluate the Magnaporthe oryzae pathotype diversity in new commercial irrigated rice fields in the Araguaia River Valley, state of Tocantins, Brazil. The causal agent of rice blast has heavily affected rice production in the region. Despite the efforts of breeding programs, blast resistance breakdown has been recorded shortly after the release of new resistant cultivars developed for the region. Among the causes of resistance breakage is the capacity of the fungus to rapidly develop new pathotypes. A sample of 479 M. oryzae monosporic isolates was obtained and tested using the international rice blast differential set. Isolate collections were made in small areas designed as trap nurseries and in scattered sites in their vicinity. Analysis of 250 M. oryzae isolates from three trap nurseries indicated the presence of 45 international M. oryzae races belonging to seven pathotype groups (IA-IG). In the isolates tested, 61 M. oryzae pathotypes belonging to all but the IH group were detected. The new areas of irrigated rice in the Araguaia River Valley have the highest diversity of M. oryzae pathotypes reported so far in Brazil.

'Royal Gala' apple quality stored under ultralow oxygen concentration and low temperature conditions

The objective of this work was to evaluate the interaction of ultralow oxygen concentrations (ULO) with storage temperatures and carbon dioxide partial pressures and its influence on fruit quality preservation and on the occurrence of physiological disorders in 'Royal Gala' apples. The experiment was carried out in a completely randomized design, with four replicates 25-fruit. ULO conditions (1.0 kPa O2 + 2.0 kPa CO2; 0.8 kPa O2 + 1.5 kPa CO2; 0.8 kPa O2 + 1.0 kPa CO2; 0.6 kPa O2 + 1.5 kPa CO2; and 0.6 kPa O2 + 1.0 kPa CO2) were tested at 0, 0.5 and 1.0°C, in a 5x3 factorial arrangement. Fruit quality and ripening analyses were performed after eight-month storage plus seven days of shelf-life at 20°C. Oxygen partial pressures below 0.8 kPa increased the occurrence of internal breakdown and mealiness. The best ULO condition was 1.0 kPa O2 + plus 2.0 kPa CO2 at 1.0°C. The interaction of ULO conditions and storage temperatures shows the need of increasing O2 partial pressure at higher storage temperatures.

Characterization of phosphate structures in biochar from swine bones

The objective of this work was to develop an alternative methodology to study and characterize the phosphate crystalline properties, directly associated with solubility and plant availability, in biochar from swine bones. Some phosphate symmetry properties of pyrolyzed swine bones were established, using solid state nuclear magnetic resonance spectroscopy, principal component analysis, and multivariate curve resolution analysis, on four pyrolyzed samples at different carbonization intensities. Increasing carbonization parameters (temperature or residence time) generates diverse phosphate structures, increasing their symmetry and decreasing the crossed polarizability of the pair ¹H-31P, producing phosphates with, probably, lower solubility than the ones produced at lower carbonization intensity. Additionally, a new methodology is being developed to study and characterize phosphate crystalline properties directly associated with phosphate solubility and availability to plants.

Effects of levels of nitrogen and potassium on yield and fruit maturation of irrigated guava trees in the São Francisco Valley

Yield and physical and chemical characteristics of 'Paluma' guava fruit were evaluated as a function of the harvest at different maturity stages, under influence of nitrogen and potassium fertilization, in Petrolina, State of Pernambuco, Brazil. Fertilizer rates were 67 kg N + 33 kg K2O, 133 kg N + 67 kg K2O, 200 kg N + 100 kg K2O and 267 kg N + 133 kg K2O per hectare. Fruits were evaluated at maturity stages 2, 3, 4 and 5, established according to peel color. Higher doses of N and K induced higher yields. Nevertheless, fertilization with 200 kg of N + 100 kg of K per hectare improved fruit quality, delaying ascorbic acid breakdown and conserving pulp firmness. Main changes took place at maturity stages 4 and 5, when the fruit should present ideal conditions for consumption, namely the increase on soluble solids and soluble sugars content.

Apple biological and physiological disorders in the orchard and in postharvest according to production system

The study aimed to evaluate the incidence of biological and physiological disorders in the field and postharvested apples cvs. Gala, Fuji and Catarina grown in four production systems: conventional, organic transition, integrated and organic. Apples were evaluated for damages related to biological and physiological disorders in the orchard and after harvest. The greatest damages were attributed to pests, especially Anastrepha fraterculus in the organic system and Grapholita molesta in the organic transition. Apples produced in organic orchards had higher damage levels caused by postharvest physiological disorders than those grown in other production systems. For apples becoming from organic orchards most of the damage was due to lenticels breakdown and degeneration ('Gala'), and bitter pit ('Fuji' and 'Catarina'). The incidence of postharvest rot was not influenced by apple production system.

A Eterna Busca do Indivisível: do Átomo Filosófico aos Quarks e Léptons

The fascinating search of the inner boundaries of the Universe, has been entangled, since the birth of greek philosophy 25 centuries ago, with the main epistemological changes in the History of Science. This paper does not intend to present a systematic description of the discovery of the elementary particles. By stressing the main achievements of the knowledge of matter's structure and their dependence on symmetry arguments, it is argued that even considering profound differences in each historical period, there is a paradgima of atom shared by Chemistry and Particle Physics. This text could help High School Teachers of Chemistry and Physics, as well as motivate them, in the challenge of explaining to their pupils how the idea of atom evolved.

Defeitos superficiais em 2H-WS2 observados por microscopia de tunelamento

Scanning tunnelling microscopy (STM) was used to characterise the basal surface of fresh cleaved crystals of 2H-WS2. Although no impurity or stacking faults could be detected by X-ray diffraction, STM images obtained with negative bias voltage showed two kinds of defects. These defects were attributed to an iodine derivative used as transport agent. In a flat surface free of defects, an image with atomic resolution was achieved with sulphur distances and angles as expected for hexagonal symmetry of 2H-WS2.

The ESRg matrix for strong field d5 systems

This review has tried to collect and correlate all the various equations for the g matrix of strong field d5 systems obtained from different basis sets using full electron and hole formalism calculations. It has corrected mistakes found in the literature and shown how the failure to properly take in symmetry boundary conditions has produced a variety of apparently inconsistent equations in the literature. The review has reexamined the problem of spin-orbit interaction with excited t4e states and finds that the earlier reports that it is zero in octahedral symmetry is not correct. It has shown how redefining what x, y, and z are in the principal coordinate system simplifies, compared to previous methods, the analysis of experimental g values with the equations.

Planejamento racional de fármacos baseado em produtos naturais

In the area of drug discovery, natural products represent a myriad of templates for new lead discovery. It is, however, most unlikely that the bioactive principle itself shall become a drug; it is much more likely that a medicinal chemistry project needs to be initiated as soon the potency or selectivity or specificity of the new natural product candidate has been disclosed. Brazil has an enormous biodiversity where just a few has been disclosed. Nevertheless, it urges to initiate a joint collaboration in order to circumvent a major breakdown linking between natural products and medicinal chemistry in this country. This paper is intended to encourage people to follow up one of the most pushing forward enterprise that needs to be settled: the pharmaceutical industry.

Análise de glicocorticosteróides por CG-EM: uma nova abordagem de derivatização para o controle de dopagem no esporte

Glucocorticosteroids (CT) show a powerful anti-inflammatory effect. In view of this, they are extensively used in sports medicine, but their misuse (systemic administration) can lead to severe injuries on athletes and has been restricted by the IOC in recent years. For GC-MS analysis, a derivatization step is necessary in order to convert them to a stable form, thus preventing thermal breakdown with the loss of the ketone side chain. Derivatization of CT is reviewed and a new approach of silylation is presented for screening of CT in urine.

Síntese, caracterização e propriedades espectroscópicas de criptatos de lantanídeo do tipo [LnÌ(bipy)2py(CO2Et) 2(3+)]

This work reports on the synthesis, characterization (infrared and hidrogen nmr spectra) and photophysical properties (luminescence spectra and emission quantum yield) of the lanthanide cryptates [LnÌ(bipy)2py(CO2Et) 2]3+ with Ln = Eu3+, Tb3+ or Gd3+, which can be applied as efficient Light-Conversion-Molecular-Devices. From emission spectra of [EuÌ(bipy)2py(CO2Et) 2]3+ it was possible to assign C3 symmetry to the metal ion. The spectroscopic studies show a higher emission quantum yield (q=25%) for [TbÌ(bipy)2py(CO2Et) 2]3+ in aqueous solution, whereas the europium cryptate presents q=14%. This is justified by a more efficient energy transfer between triplet and emission levels of terbium (T->5D4).