Correlation between mandibular gland secretion and cuticular hydrocarbons in the stingless bee Melipona quadrifasciata

We investigated whether Melipona quadrifasciata worker mandibular gland secretions contribute directly to their cuticular hydrocarbon profile. The mandibular gland secretion composition and cuticular surface compounds of newly emerged worker bees, nurse bees, and foragers were determined by gas chromatography and mass spectrometry and compared. Both the mandibular gland secretions and the cuticular surface compounds of all worker stages were found to be composed almost exclusively of hydrocarbons. Although the relative proportion of hydrocarbons from the cuticular surface and gland secretion was statistically different, there was a high similarity in the qualitative composition between these structures in all groups of bees. © FUNPEC-RP.

Geotermobarometria de Granulitos Associados à Supracrustais na Porção Norte do Complexo Guaxupé - Região de Arceburgo - Santa Cruz do Prata, MG

This paper is a contribution for the understanding of the geological evolution of Guaxupé Complex. New data on petrography and mineral chemistry as well as estimates of metamorphic (P-T) conditions in the region of Arceburgo - Santa Cruz do Prata (MG) Brazil, at the southern portion of the Brasília Belt, more specifically at the Guaxupé Complex (Domain) are now presented. The lithotypes are high-grade metamorphic rocks subdivided into two groups: metasediments and granulites (orthoderivates). Chemical analysis of minerals was performed in three steps including core and rim of amphibole, pyroxene, feldspar, biotite, and garnet from samples of the following rock types: enderbites, mafic granulites, charnockites, and alkali feldspar charnockites. Results obtained with geothermobarometric calculations show metamorphic peak around 900°C of T and 10 kbar of P. Enderbites and tonalite granulites (mafic) show the highest values of temperature and pressure, while alkali feldspar charnockites show the lowest probably due to their late generation in relation to mafic rock types (enderbites and mafic tonalite granulite). Chemical mineral analysis in metamorphic parageneses and geothermobarometric calculations indicate that the possible metamorphic peak may be higher than 900°C of temperature and around 10 kbar of pressure, within a isothermal decompression (ITD) regime.

Doses de potássio em cobertura na cultura da abóbora

Although there are recommendations for the fertilization of commercial squash crops, studies which connect the effect of topdressing potassium fertilization and yield are still rare. Thus, this study aimed at evaluating topdressing potassium doses on squash (Mirian hybrid) yield, in an experimental farm of the Universidade Estadual Paulista Júlio de Mesquita Filho, in São Manuel, São Paulo State, Brazil. The experimental design was randomized blocks, with five treatments (0.0 kg ha-1, 50.0 kg ha-1, 100.0 kg ha-1, 200.0 kg ha-1 and 400.0 kg ha-1 of K2O) and six replications. Plant growth parameters, yield and fruit quality were evaluated. After harvesting, plant (leaves + stem) and soil macronutrients were submitted to chemical analysis and data to variance and regression analysis. It was concluded that the highest yield resulted from the topdressing dose of 199.0 kg ha-1 of K2O. A reduction in calcium and magnesium contents in the plant canopy and a higher K+ content in the soil were observed for increasing K2O levels.

Chlorine disinfection of dye wastewater: Implications for a commercial azo dye mixture

Azo dyes, the most widely used family of synthetic dyes, are often employed as colorants in areas such as textiles, plastics, foods/drugs/cosmetics, and electronics. Following their use in industrial applications, azo dyes have been found in effluents and various receiving waters. Chemical treatment of effluents containing azo dyes includes disinfection using chlorine, which can generate compounds of varying eco/genotoxicity. Among the widely known commercial azo dyes for synthetic fibers is C.I. Disperse Red 1. While this dye is known to exist as a complex mixture, reports of eco/genotoxicity involve the purified form. Bearing in mind the potential for adverse synergistic effects arising from exposures to chemical mixtures, the aim of the present study was to characterize the components of commercial Disperse Red 1 and its chlorine-mediated decoloration products and to evaluate their ecotoxicity and mutagenicity. In conducting the present study, Disperse Red 1 was treated with chlorine gas, and the solution obtained was analyzed with the aid of LC-ESI-MS/MS to identify the components present, and then evaluated for ecotoxicity and mutagenicity, using Daphnia similis and Salmonella/microsome assays, respectively. The results of this study indicated that chlorination of Disperse Red 1 produced four chlorinated aromatic compounds as the main products and that the degradation products were more ecotoxic than the parent dye. These results suggest that a disinfection process using chlorine should be avoided for effluents containing hydrophobic azo dyes such commercial Disperse Red 1. © 2012 Elsevier B.V..

Caracterização química e mineralógica de azulejos portugueses do centro histórico de São Luís-MA (Brasil): Uma aproximação à mineralogia e à temperatura de queima das matérias-primas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise química da folha d de abacaxizeiro cv. smooth cayenne antes e após a indução floral em função de doses e parcelamentos de nitrogênio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Superfícies geomórficas e atributos do solo em uma toposseqüência de transição várzea-terra firme

Soil attributes reflect influence of the geomorphic surfaces. Therefore, the objective of this work was to investigate the influence of the geomorphic surfaces on soil attributes in a topossequence from low lands to high lands in the Humaitá region, AM. A transect of 4.5 km, from the top of the slope towards the low lands was established and the geomorphic surfaces were identified and limited according to topographic and estratigraphic criteria, based on detailed field investigation. Twenty soil samples were collected in each one of the slope segments within the geomorphic surfaces (G.S.), at the following depths: G.S. I: LAa (0.0-0.16 and 0.48-0.79 m); G.S. II: Lad1 (0.0-0.13 and 0.44-0.70) and Lad2 (0.0-0.10 and 0.30-0.55 m); G.S. III: RYve1 (0.0-0.18 and 0.51-0.89) and RYve2 (0.0-0.23 and 0.58-0.91 m). The sampling depths were determined by the surface and subsurface horizon depths, defined during the soil morphological description. Physical analysis involved particle size distribution, disperse clay, soil and particle density and total porosity. The chemical analysis involved determinations of pH in water and KCl, exchangeable cations, exchangeable Al, total acidity (H+Al), available P, organic carbon. The relief variations contributed to the presence of dystrophic soils in the geomorphic surface I and eutrophic soils in the geomorphic surface III. The multivariate statistical techniques were able to separate three heterogeneous groups, equivalent to the mapped geomorphic surfaces.

Study of adsorption and preconcentration by using a new silica organomodified with [3-(2,2′-dipyridylamine)propyl] groups

In this work, a silica surface chemically modified with [3-(2,2′-dipyridylamine)propyl] groups, named [3-(2,2′- dipyridylamine)propyl]silica (Si-Pr-DPA) was prepared, characterized, and evaluated for its heavy metal adsorption characteristics from aqueous solution. To our knowledge, we are the first authors who have reported the present modification. The material was characterized using infrared spectroscopy, SEM, and NMR 29Si and 13C solid state. Batch and column experiments were conducted to investigate for heavy metal removal from dilute aqueous solution by sorption onto Si-Pr-DPA. From a number of studies the affinity of various metal ions for the Si-Pr-DPA sorbent was determined to follow the order Fe(III) > Cr(III) >> Cu(II) > Cd(II) > Pb(II) > Ni(II). Two standard reference materials were used for checking the accuracy and precision of the method. The proposed method was successfully applied to the analysis of environmental samples. This ligand material has great advantage for adsorption of transition-metal ions from aqueous medium due to its high degree of organofunctionalization associated with the large adsorption capacity, reutilization possibility, and rapidity in reaching the equilibrium. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assessment of the genotoxicity of two agricultural residues after processing by diplopods using the Allium cepa assay

Agroindustrial by-products and residues from treatment of sewage sludge have been recently recycled as soil amendments. This study was aimed at assessing toxic potential of biosolid, obtained from a sewage treatment plant (STP), vinasse, a by-product of the sugar cane industry, and a combination of both residues using Allium cepa assay. Bioprocessing of these samples by a terrestrial invertebrate (diplopod Rhinocricus padbergi) was also examined. Bioassay assembly followed standards of the Brazilian legislation for disposal of these residues. After adding residues, 20 diplopods were placed in each terrarium, where they remained for 30 days. Chemical analysis and the A. cepa assay were conducted before and after bioprocessing by diplopods. At the end of the bioassay, there was a decrease in arsenic and mercury. For the remaining metals, accumulation and/or bioavailability varied in all samples but suggested bioprocessing by animals. The A. cepa test revealed genotoxic effects characterized by different chromosome aberrations. Micronuclei and chromosome breaks on meristematic cells and F1 cells with micronuclei were examined to assess mutagenicity of samples. After 30 days, the genotoxic effects were significantly reduced in the soil + biosolid and soil + biosolid + vinasse groups as well as the mutagenic effects in the soil + biosolid + vinasse group. Similar to vermicomposting, bioprocessing of residues by diplopods can be a feasible alternative and used prior to application in crops to improve degraded soils and/or city dumps. Based on our findings, further studies are needed to adequately dispose of these residues in the environment. © 2013 Springer Science+Business Media Dordrecht.

Organotins: A review of their reproductive toxicity, biochemistry, and environmental fate

The review purposes are to (1) evaluate the experimental evidence for adverse effects on reproduction and metabolism and (2) identify the current knowledge of analytical procedures, biochemistry and environmental aspects relating to organotins. Organotins are pollutants that are used as biocides in antifouling paints. They produce endocrine-disrupting effects in mollusks, such as imposex. In rodents, organotin exposure induces developmental and reproductive toxicity as well as alteration of metabolic homeostasis through its action as an obesogen. The adverse effects that appear in rodents have raised concerns about organotins' potential health risk to humans in relation to organotin exposure. At present, triorganotin, such as tributyltin, have been demonstrated to produce imposex, and mammalian reproductive and metabolic toxicity. For most mammals, triorganotin exposure predominantly occurs through the ingestion, and this compound can cross the placenta. With these risks in mind, it is important to improve our knowledge of organotins' effects on environmental health. © 2012 Elsevier Inc.

Micro-raman spectroscopic characterization of a CR-39 detector

Characterization by micro-Raman spectroscopy of polymeric materials used as nuclear track detectors reveals physico-chemical and morphological information on the material's molecular structure. In this work, the nuclear track detector poly(allyl diglycol carbonate), or Columbia Resin 39 (CR-39), was characterized according to the fluence of alpha particles produced by a 226Ra source and chemical etching time. Therefore, damage of the CR-39 chemical structure due to the alpha-particle interaction with the detector was analyzed at the molecular level. It was observed that the ionization and molecular excitation of the CR-39 after the irradiation process entail cleavage of chemical bonds and formation of latent track. In addition, after the chemical etching, there is also loss of polymer structure, leading to the decrease of the group density C-O-C (∼888 cm-1), CH=CH (∼960 cm -1), C-O (∼1110 cm-1), C-O-C (∼1240 cm -1), C-O (∼1290 cm-1), C-O (∼1741 cm -1), -CH2- (∼2910 cm-1), and the main band -CH2- (∼2950 cm-1). The analyses performed after irradiation and chemical etching led to a better understanding of the CR-39 molecular structure and better comprehension of the process of the formation of the track, which is related to chemical etching kinetics. Copyright © 2013 Society for Applied Spectroscopy.

Source-driven remobilizations of nutrients within stem wood in Eucalyptus grandis plantations

Nutrient remobilizations in tree ligneous components have been little studied in tropical forests. A complete randomized block design was installed in Brazilian eucalypt plantations to quantify the remobilizations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) within stem wood. Three treatments were studied: control with neither K nor Na addition (C), 3 kmol ha-1 K applied (+K), and 3 kmol ha-1 Na applied (+Na). Biomass and nutrient contents were measured in the stem wood of eight trees destructively sampled at 1, 2, 3 and 4 years after planting in each treatment and annual rings were localized on discs of wood sampled every 3 m in half of the trees. Chemical analyses and wood density measurements were performed individually for each ring per level and per tree sampled. Nutrient remobilizations in annual rings were calculated through mass balance between two successive ages. Our results show that nutrient remobilizations within stem wood were mainly source-driven. Potassium and Na additions largely increased their concentration in the outer rings as well as the amounts remobilized in the first 2 years after the wood formation. The amount of Na remobilized in annual rings was 15 % higher in +Na than in +K the fourth year after planting despite a 34 % higher production of stem wood in +K leading to a much higher nutrient sink. A partial substitution of K by Na in the remobilizations within stem wood might contribute to enhancing Eucalyptus grandis growth in K-depleted soils. © 2013 Springer-Verlag Berlin Heidelberg.

Efeitos benéficos de probióticos no intestino de juvenis de tilápia-do-nilo

The aim of this study was to evaluate the survival rate, the intestinal microbiota, the mucosal integrity, and the carcass quality of juvenile Nile Tilapia, Oreochromis niloticus, after 80 days being fed on a diet containing probiotic additive (Bacillus cereus 4.0×108 CFUg-1 and Bacillus subtilis 4.0×108 CFUg-1), at the ratio of 4g/kg of pelleted feed. The completely randomized design with two treatments was used: one control group and one group fed on the mentioned diet. The evaluation of survival rate, the intestinal microbiota analysis by microbiological culture, histomorphometrical analysis of intestinal mucosa and chemical analysis of carcass was performed. The results showed that tilapias from the treated group had higher relative survival rate (P<0.05) than the control group, higher number of colony-forming units (P<0.05) regarding intestinal colonization by B. cereus and B. subtilis, and higher rates of intestinal mucosal integrity (P<0.05), evaluated by histomorphometry. As for the latter, the group being fed on feed with probiotic additive was observed to have higher and larger villi, besides having a higher number of goblet cells than the control group. Concerning the carcass quality, the results showed that there was positive interference (P<0.05) of the probiotic on the treated group in comparison to the control group as in regard to levels of protein and ether extract. These results allow the inference that the supplementation with probiotic, as tested in this experiment, led to the intestinal colonization by beneficial bacteria and resulted in higher relative survival rate, decreased the mucosal desquamation and helped in the increase of the number of goblet cells.

Characterization of natural rubber/gold nanoparticles SERS-active substrate

Natural rubber/gold nanoparticles membranes (NR/Au) were studied by ultrasensitive detection and chemical analysis through surface-enhanced Raman scattering and surface-enhanced resonance Raman scattering in our previous work (Cabrera et al., J. Raman Spectrosc. 2012, 43, 474). This article describes the studies of thermal stability and mechanical properties of SERS-active substrate sensors. The composites were prepared using NR membranes obtained by casting the latex solution as an active support (reducing/establishing agents) for the incorporation of colloidal gold nanoparticles (AuNPs). The nanoparticles were synthesized by in situ reduction at different times. The characterization of these sensors was carried out by thermogravimetry, differential scanning calorimetry, scanning electron microscopy (SEM) microscopy, and tensile tests. It is suggested an influence of nanoparticles reduction time on the thermal degradation of NR. There is an increase in thermal stability without changing the chemical properties of the polymer. For the mechanical properties, the tensile rupture was enhanced with the increase in the amount of nanoparticles incorporated in the material. © 2013 Wiley Periodicals, Inc.

The effect of the solute on the structure, selected mechanical properties, and biocompatibility of Ti-Zr system alloys for dental applications

New titanium alloys have been developed with the aim of utilizing materials with better properties for application as biomaterials, and Ti-Zr system alloys are among the more promising of these. In this paper, the influence of zirconium concentrations on the structure, microstructure, and selected mechanical properties of Ti-Zr alloys is analyzed. After melting and swaging, the samples were characterized through chemical analysis, density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, and elasticity modulus. In-vitro cytotoxicity tests were performed on cultured osteogenic cells. The results showed the formation essentially of the α′ phase (with hcp structure) and microhardness values greater than cp-Ti. The elasticity modulus of the alloys was sensitive to the zirconium concentrations while remaining within the range of values of conventional titanium alloys. The alloys presented no cytotoxic effects on osteoblastic cells in the studied conditions. © 2013 Elsevier B.V. All rights reserved.