Mitigation of N2O emissions from grassland by nitrification inhibitor and actilith F2 applied with fertilizer and cattle slurry

Nitrous oxide (N2O) is involved in both ozone destruction and global warming. In agricultural soils it is produced by nitrification and denitrification mainly after fertilization. Nitrification inhibitors have been proposed as one of the management tools for the reduction of the potential hazards of fertilizer-derived N2O. Addition of nitrification inhibitors to fertilizers maintains soil N in ammonium form, thereby gaseous N losses by nitrification and denitrification are less likely to occur and there is increased N utilization by the sward. We present a study aimed to evaluate the effectiveness of the nitrification inhibitor dicyandiamide (DCD) and of the slurry additive Actilith F2 on N2O emissions following application of calcium ammonium nitrate or cattle slurry to a mixed clover/ryegrass sward in the Basque Country. The results indicate that large differences in N2O emission occur depending on fertilizer type and the presence or absence of a nitrification inhibitor. There is considerable scope for immediate reduction of emissions by applying DCD with calcium ammonium nitrate or cattle slurry. DCD, applied at 25 kg ha-1, reduced the amount of N lost as N2O by 60% and 42% when applied with cattle slurry and calcium ammonium nitrate, respectively. Actilith F2 did not reduce N2O emissions and it produced a long lasting mineralization of previously immobilized added N.

Geochemical Study of the Itabirite Iron Ores of the Alegria Mine - Quadrilátero Ferrífero, Minas Gerais, Brazil

The iron ores of Alegria mine are composed of itabirites enclosing minor bodies of high-grade ores. The itabirites are classified according to mineralogical composition in five types: martite-rich, goethite-rich, specularite-rich, magnetite-rich and anphibolite-rich ores. The hematites are martite-rich, magnetite-rich, specularite-rich and more rarely, amphibolite-rich. Other classification criteria of the ores are based on the physical properties and the degree of compaction. As such, the itabirites and hematites can be classified as hard, friable and soft types. The mineralogical/textural evolution of the ores is linked to the pressure and temperature conditions that accompanied the tectonic processes in anphibolite facies and the different degrees of subsequent surficial weathering processes. Petrographic and microstructural studies indicate that the magnetite and amphibole bearing itabirites represent the parent rocks that created the other itabirites and that the specularite itabirites and the hard martite types are related to silica dissolution and redeposition in zones of high and low strain. Most of itabirites ores correspond to chert oxide facies banded iron formation, except the goethite and amphibole bearing itabirite that resemble a silicate or oxide-silicate facies with minor carbonate impurities. The great mass and pods of soft martite itabirites are probably shaley oxide facies BIFs with little volcanic contribution. Trace element contents of the Alegria's itabirites show strong dissimilarities with BIFs associated with volcanism (Algoma type), but closely ressemble to the Lake Superior type, with high content in Cr, Co and low V, Ni, Cu and Zn. Although the absolute contents of REE present in the Alegria's itabirites are, in general very low, the pattern when normalised by NASC is similar to the great majority of the Archean and Paleoproterozoic BIFs elsewhere in the world, and characterised by positive Eu anomaly.

Maturity degree of composts from municipal solid wastes evaluated by differential scanning calorimetry

Differential scanning calorimetry (DSC) in association with chemical analysis was applied to assess the maturity reached by the organic fraction of Municipal Solid Wastes (MSW) subjected to composting processes with manual and fixed aeration and sampled at different composting times. Thermograms showed that the difference in the treatments, i.e., the manual aeration and the fixed aeration, had no relevant effect on the stabilization and maturation of OM in the substrates. Common thermal effects observed were: a low temperature endotherm assigned to dehydration and/or loss of peripheral polysaccharides chains; a medium temperature exotherm assigned to loss of peptidic structures, and a high temperature exotherm assigned to oxydation and polycondensation of aromatic nuclei of the molecule. Results obtained suggest that in the experimental conditions used, a shorter time of composting (about 30 d) appears adequate, in order to limit the extended mineralization of OM, whereas a prolonged composting time (up to 132 d) would produce a compost of poor quality with high ash content and low OM content.

Photoelectrocatalytic degradation of Remazol Brilliant Orange 3R on titanium dioxide thin-film electrodes

Degradation of reactive dye Remazol Brilliant Orange 3R (RBO) has been performed using photoeletrocatalysis. A biased potential is applied across a titanium dioxide thin-film photoelectrode illuminated by UV light. It is suggested that charges photogenerated at the electrode surface give rise to chlorine generation and powerful oxidants (OH) that causes the dye solution to decolorize. Rate constants calculated from color decay versus time reveal a first-order reaction up to 5.0×10-5 mol l-1 in dye concentration. The best experimental conditions were found to be pH 6.0 and 1.0 mol l-1 NaCl when the photoelectrode was biased at +1V (versus SCE). Almost complete mineralization of the dye content (70% TOC reduction) was achieved in a 3-h period using these conditions. Effects of other electrolytes, dye concentration and applied potentials also have been investigated and are discussed. © 2003 Elsevier Science B.V. All rights reserved.

Determination of calcium by atomic absorption spectrophotometry applied to the preparation of alginate:chitosan complexes

Polysaccharicles, as alginate and chitosan, have been used to obtain modified release dosage forms. Alginate, due to its property of building gels during the complex formation with calcium ions, allows the building of capsules containing a core constituted by calcium alginate. This work had for objective to determine the appropriate calcium concentration for the preparation of alginate-chitosan capsules, by means of calcium quantification using atomic absorption spectrophotometry. The methodology of calcium quantification was validated through analysis of the limit of detection, precision, accuracy and recovery of the method. The capsules, containing or not the drug, were prepared by the complex coacervation/ionotropic gelification method. Calcium was quantified after samples mineralization and dilution in lantanium solution. The results showed that the amount of calcium incorporated into the capsules depends on the amount of calcium added to the medium, and this ratio increases until the concentration of 1.5% of initial calcium chloride and above this concentration there is a decrease in the proportion of calcium bonded. It was observed that the proportion of calcium that links to the polymer is inversely proportional to the amount of calcium added. The calcium amount incorporated depends on the concentration of the polymeric dispersions used as well as on the ratio between the two polymers.

Minerals in the nutrition of extremely low birth weight infants

Objective: To review the literature on the role of calcium, phosphorus and trace elements in the nutrition of extremely low birth weight infants, considering their importance for metabolism, bone mineralization and as dietary components. Sources of data: MEDLINE, the Cochrane Database of Systematic Reviews and books on nutrition were searched between 1994 and 2004. Original research studies and reviews were selected. Summary of the findings: Extremely preterm infants are frequently growth-restricted at hospital discharge as a consequence of difficulties in the provision of adequate nutrition. The long-term effects of this growth restriction need to be determined. There is a paucity of studies about the role of minerals, especially micronutrients, in the nutrition of extremely preterm infants. The principal focus of this review was on calcium and phosphorus metabolism, bone mineralization and parenteral and enteral supplementation. A critical evaluation of post-discharge nutrition and its influence upon growth and bone mineralization was presented. Selenium and zinc requirements and the role of selenium as an antioxidant with possible effects on free radical diseases of the preterm infant were discussed. Conclusions: Extremely preterm infants have low mineral reserves and, as a consequence, may have deficiencies in the postnatal period if they do not receive parenteral or enteral supplementation. More studies are needed to elucidate the actual requirements and the appropriate supplementation of micronutrients. There are controversies about the outcome and the influence of post-discharge nutrition on bone disease of prematurity. Copyright © 2005 by Sociedade Brasileira de Pediatria.

Mineralización de la paja de caña de azúcar en suelo adicionado con viñaza (suproducto de la industria del alcohol de caña de azúcar) y fertilizante nitrogenado

Cellulose is the most abundant vegetable organic compound, being derived mainly from plant residues. The decomposition of sugar-cane (Saccharum officinarum L.) straw was studied in a period up to 90 days, through variables related to the carbon cycle, such as respiratory activity and CM-cellulase (CM, cellulose microcrystalline) and CMC-cellulase (CMC, carboxymethylcellulose) activities. The treatments consisted of 0, 0.5 and 1.0% of straw, in the presence and absence of vinasse (a sugar-cane alcohol industry byproduct) and nitrogen fertilizer. The respiratory and cellulase activities increased up to the 14th day of incubation and later decreased. The respiratory activity was 1.9 and 2.3 fold larger (P < 0.05) in the soil with 0.5 and 1.0% of straw added, respectively, in relation to the control. CM- and CMC- cellulase activities also increased from 1.8 to 2.9 and from 2.3 to 2.7 fold, respectively. The vinasse addition enhanced CO 2 production and CM-cellulase activity, however, no significant effect was observed on CMC-cellulase activity. The addition of N reduced both respiratory and cellulase activities. The decomposition of the sugar-cane straw may enhance soil nutrient cycling increasing agricultural production. © 2006 Instituto de Investigaciones Agropecuarias, INIA.

Analysis of fluoride concentration in mother's milk substitutes

The aim of the present study was to determine the fluoride concentration in some brands of mother's milk substitutes and evaluate the possibility of developing dental fluorosis by consuming these products. The products, all powdered, were divided into 3 groups: infant formulae (group I, n = 7), milk-based (group M, n = 8) and soy-based (group 8, n = 3). Samples from 3 cans of different batches of each brand were reconstituted in deionized water and analyzed using the specific electrode method, after hexamethyldisiloxane (HMDS) facilitated diffusion. The fluoride content (mg F/L) of the products ranged from 0.044 to 0.326 (I), 0.014 to 0.045 (M) and 0.253 to 0.702 (S). There was significant difference in the fluoride content of cans from distinct batches (p < 0.05) in most of the brands. The reconstitution of all products in water with optimal fluoride concentration for consumption during the mineralization phase of the primary teeth could result in daily fluoride intake above 0.07 mg F/kg body weight/day. Therefore, the consumption of these products, especially when reconstituted with optimally fluoridated water, could increase the risk of developing dental fluorosis.

A meniralização dental e a atividade salivar estão reduzidas em filhotes de ratas espontaneamente hipertensas (SHR)

Several pathologies have been diagnosed in children of hypertensive mothers; however, some studies that evaluated the alterations in their oral health are not conclusive. This study analyzed the salivary gland activity and dental mineralization of offsprings of spontaneously hypertensive rats (SHR). Thirty-day-old SHR males and Wistar rats were studied. The salivary flow was evaluated by injection of pilocarpine, the protein concentration and salivary amylase activity, by the Lowry method and kinetic method at 405 nm, respectively. Enamel and dentin mineralization of the mandibular incisors was quantified with aid of the microhardness meter. The results were analyzed by the ANOVA or Student's t test (p<0.05). It was noticed that the salivary flow rate (0.026 mL/min/100 g±0.002) and salivary protein concentration (2.26mg/mL±0.14) of SHR offspring were reduced compared to Wistar normotensive offspring (0.036 mL/min/100 g±0.003 and 2.91 mg/mL±0.27, respectively), yet there was no alteration in amylase activity (SHR: 242.4 U/mL±36.9; Wistar: 163.8 U/mL±14.1). Microhardness was lower both in enamel (255.8 KHN±2.6) and dentin (59.9 KHN±0.8) for the SHR teeth compared to the Wistar teeth (enamel: 328.7 KHN±3.3 and dentin: 67.1 KHN±1.0). These results suggest that the SHR offspring are more susceptible to development of pathologies impairing oral health, once they presented lesser flow and salivary protein concentration and lower dental mineralization.

Geoquímica de gnaisses do arco magmático de goiás na região sul do estado de goiás

Granitic to trondhjemitic gneisses from the Pontalina region in the southern part of Goiás State, Central Brazil, have calcic to calc-alkaline, metaluminous to peraluminous compositions. They have low concentrations of alkaline elements, and are enriched in Ba, Sr, K, Rb in relation to Nb, Y, Zr and REE, and have negative anomalies of Nb and Ti, features which are similar to those of magmas generated in magmatic arc environments. Those rocks were previously interpreted as part of the basement of the Brasília Belt, attributed to the Archean to Paleoproterozoic, but new Sm - Nd isotopic data indicate a neoproterozoic age (TDM = 0,9 a 1,2 Ga), and the preliminary geochemical data reveal compositions similar to the gneisses of the other regions belonging to the Goiás Magmatic Arc.

Dental age in patients with Down syndrome

The aim of this research was to evaluate dental age in 102 patients with Down Syndrome, using panoramic radiographs. A software program developed by the Discipline of Radiology, School of Dentistry of São José dos Campos, São Paulo State University (UNESP), was used. A table of mineralization chronology of permanent teeth among Brazilians conceived by Nicodemo, Moraes and Medici Filho was used within the software. Statistical analysis of the results showed that 70.91% of the males land 61.21% of the females presented advanced dental age. Only 32.09% of the males and 39.79% of the females presented delayed dental age. Regarding the differences between the dental and chronological ages, two thirds of the males and females presented dental age with differences of up to 12 months, which means that they can be considered to be within normal standards, whereas only 18.87% of the males and 10.21% of the females presented dental age outside normal standards, with differences of over 24 months. In conclusion, the majority of the patients with Down Syndrome were considered to be within the normal standards of mineralization chronology.

Inibição da mineralização de compostos nitrogenados de lixiviado de macrófita aquática: Adequação metodológica

This study aimed to establish the adequate concentrations of nitrapyrin for the effective inhibition of oxygen demand required for the oxidation of nitrogen compounds during aerobic mineralization of leachate. The aquatic macrophyte Myriophyllum aquaticum was used as a source of dissolved organic matter (DOM). The leachate was incubated in several chambers, containing different composition and treatments: (i) treatment with leachate (DOM), (ii) treatment with DOM plus nitrapyrin in different concentrations (10; 25 and 50 mg L-1), aiming at finding the right concentration that inhibits the nitrification process, (iii) treatment with DOM plus NH4SO 2, (iv) treatment containing DOM and nitrapyrin plus NH 4SO2, and (v) treatment with DOM plus azide. The dissolved oxygen amount in each incubation treatment was periodically measured. The results indicated that the ratio of 10 mg L-1 of nitrapyrin for each 10 mg C of leachate is efficient in inhibiting the oxidation of nitrogen compounds from aquatic macrophytes.

Determination of calcium and magnesium in hydroethanolic extracts of propolis by atomic absorption flame spectrophotometry

Propolis is a natural product collected by honeybees and has a large range of pharmacological activity, including antimicrobial, antitumoral, antioxidant and anti-inflammatory. Its use as a popular medicine is increasing all over the world, creating a need for quality control of the commercial products. In this study the levels of calcium and magnesium in commercial hydroalcoholic propolis extracts from varies states of Brazil were determined by atomic absorption flame spectrophotometry and different values were obtained for northern and southern states. This study can be extended to the analysis of metals that are harmful to health. The results showed that the calibration curves were linear over a wide concentration range (0.5-4.0 μg.mL -1 for calcium and 0.05-0.4 μg.mL -1 for magnesium) with good correlation coefficients (0.999 and 0.988, respectively). Good analytical recovery (94%) was obtained. The proposed method showed adequate precision and relative standard deviation lower than 2 %. The method is accurate and precise as well as having advantages such as simplicity and speed.

Iron determination by FAAS in fish feed and feces after ultrasound-assisted extraction

This paper proposes a method to determine iron in samples of fish feed and feces using ultrasound in the extraction of the analyte and in subsequent quantification by flame atomic absorption spectrometry. Using HCl 0.10 mol L -1 as the extraction solution, the optimal conditions of extraction were found to be: granulometry of the sample <60 μm; a sonication time of five cycles of 10 s and sonication power of 136 W. The method was applied in studies of the availability of iron in four food sources used in the diet of Nile Tilapia. The results obtained with the proposed extraction method allowed us to calculate the coefficients of apparent digestibility of iron in the food sources, which was not possible when using results obtained from samples mineralized by acid digestion. © Springer Science+Business Media, LLC 2008.