Estudo comparativo de métodos para a determinação da concentração de carbono em solos com altos teores de Fe (Latossolos)

Soil organic matter (SOM) plays an important role in physical, chemical and biological properties of soil. Therefore, the amount of SOM is important for soil management for sustainable agriculture. The objective of this work was to evaluate the amount of SOM in oxisols by different methods and compare them, using principal component analysis, regarding their limitations. The methods used in this work were Walkley-Black, elemental analysis, total organic carbon (TOC) and thermogravimetry. According to our results, TOC and elemental analysis were the most satisfactory methods for carbon quantification, due to their better accuracy and reproducibility.

Genetic potential of a maize population from Southern Brazil for the modified convergent-divergent selection scheme

Maize (Zea mays L.) is a very important cereal to world-wide economy which is also true for Brazil, particularly in the South region. Grain yield and plant height have been chosen as important criteria by breeders and farmers from Santa Catarina State (SC), Brazil. The objective of this work was to estimate genetic-statistic parameters associated with genetic gain for grain yield and plant height, in the first cycle of convergent-divergent half-sib selection in a maize population (MPA1) cultivated by farmers within the municipality of Anchieta (SC). Three experiments were carried out in different small farms at Anchieta using low external agronomic inputs; each experiment represented independent samples of half-sib families, which were evaluated in randomized complete blocks with three replications per location. Significant differences among half-sib families were observed for both variables in all experiments. The expected responses to truncated selection of the 25% better families in each experiment were 5.1, 5.8 and 5.2% for reducing plant height and 3.9, 5.7 and 5.0% for increasing grain yield, respectively. The magnitudes of genetic-statistic parameters estimated evidenced that the composite population MPA1 exhibits enough genetic variability to be used in cyclical process of recurrent selection. There were evidences that the genetic structure of the base population MPA1, as indicated by its genetic variability, may lead to expressive changes in the traits under selection, even under low selection pressure.

Contribution of soil organic carbon to the ion exchange capacity of tropical soils

Highly weathered soils represent about 3 billion ha of the tropical region. Oxisols represent about 60% of the Brazilian territory (more than 5 million km 2), in areas of great agricultural importance. Soil organic carbon (SOC) can be responsible for more than 80% of the cation exchange capacity (CEC) of highly weathered soils, such as Oxisols and Ultisols. The objective of this study was to estimate the contribution of the SOC to the CEC of Brazilian soils from different orders. Surface samples (0.0 to 0.2 m) of 30 uncultivated soils (13 Oxisols, 6 Ultisols, 5 Alfisols, 3 Entisols, I Histosol, 1 Inceptisol. and I Molisol), under native forests and from reforestation sites from Sao Paulo State, Brazil, were collected in order to obtain a large variation of (electro)chemical, physical, and mineralogical soil attributes. Total content of SOC was quantified by titulometric and colorimetric methods. Effective cation exchange capacity (ECEC) was obtained by two methods: the indirect method-summation-estimated the ECECi from the sum of basic cations (Ca+ Mg+ K+ Na) and exchangeable Al; and the direct ECECd obtained by the compulsive exchange method, using unbuffered BaCl2 solution. The contribution of SOC to the soil CEC was estimated by the Bennema statistical method. The amount of SOC var ied from 6.6 g kg(-1) to 213.4 g kg(-1). while clay contents varied from 40 g kg(-1) to 716 g kg(-1). Soil organic carbon contents were strongly associated to the clay contents, suggesting that clay content was the primary variable in controling the variability of SOC contents in the samples. Cation exchange capacity varied from 7.0 mmol(c) kg(-1) to 137.8 mmol(c) kg(-1) and had a positive Correlation with SOC. The mean contribution (per grain) of the SOC (1.64 mmol(c)) for the soil CEC was more than 44 times higher than the contribution of the clay fraction (0.04 mmol(c),). A regression model that considered the SOC content as the only significant variable explained 60% of the variation in the soil total CEC. The importance of SOC was related to soil pedogenetic process, since its contribution to the soil CEC was more evident in Oxisols with predominance of Fe and Al (oxihydr)oxides in the mineral fraction or in Ultisols, that presented illuviated clay. The influence of SOC in the sign and in the magnitude of the net charge of soils reinforce the importance of agricultural management systems that preserve high levels of SOC, in order to improve their sustainability.

A Graphical Representation Model for Telemedicine and Telehealth Center Sustainability

This study shows the creation of a graphical representation after the application of a questionnaire to evaluate the indicative factors of a sustainable telemedicine and telehealth center in Sao Paulo, Brazil. We categorized the factors into seven domain areas: institutional, functional, economic-financial, renewal, academic-scientific, partnerships, and social welfare, which were plotted into a graphical representation. The developed graph was shown to be useful when used in the same institution over a long period and complemented with secondary information from publications, archives, and administrative documents to support the numerical indicators. Its use may contribute toward monitoring the factors that define telemedicine and telehealth center sustainability. When systematically applied, it may also be useful for identifying the specific characteristics of the telemedicine and telehealth center, to support its organizational development.

Calibration of the dietary data obtained from the Brazilian center of the Natural History of HPV Infection in Men study: the HIM Study

The objective of this study was to estimate the regressions calibration for the dietary data that were measured using the quantitative food frequency questionnaire (QFFQ) in the Natural History of HPV Infection in Men: the HIM Study in Brazil. A sample of 98 individuals from the HIM study answered one QFFQ and three 24-hour recalls (24HR) at interviews. The calibration was performed using linear regression analysis in which the 24HR was the dependent variable and the QFFQ was the independent variable. Age, body mass index, physical activity, income and schooling were used as adjustment variables in the models. The geometric means between the 24HR and the calibration-corrected QFFQ were statistically equal. The dispersion graphs between the instruments demonstrate increased correlation after making the correction, although there is greater dispersion of the points with worse explanatory power of the models. Identification of the regressions calibration for the dietary data of the HIM study will make it possible to estimate the effect of the diet on HPV infection, corrected for the measurement error of the QFFQ.

Reactivity, photolability, and computational studies of the ruthenium nitrosyl complex with a substituted cyclam fac-[Ru(NO)Cl(2)(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl center dot H(2)O

Chemical reactivity, photolability, and computational studies of the ruthenium nitrosyl complex with a substituted cyclam, fac-[Ru(NO)Cl(2)(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl center dot H(2)O ((1-carboxypropyl) cyclam = 3-(1,4,8,11-tetraazacyclotetradecan-1-yl) propionic acid)), (I) are described. Chloride ligands do not undergo aquation reactions (at 25 degrees C, pH 3). The rate of nitric oxide (NO) dissociation (k(obs-NO)) upon reduction of I is 2.8 s(-1) at 25 +/- 1 degrees C (in 0.5 mol L(-1) HCl), which is close to the highest value found for related complexes. The uncoordinated carboxyl of I has a pK(a) of similar to 3.3, which is close to that of the carboxyl of the non coordinated (1-carboxypropyl) cyclam (pK(a) = 3.4). Two additional pK(a) values were found for I at similar to 8.0 and similar to 11.5. Upon electrochemical reduction or under irradiation with light (lambda(irr) = 350 or 520 nm; pH 7.4), I releases NO in aqueous solution. The cyclam ring N bound to the carboxypropyl group is not coordinated, resulting in a fac configuration that affects the properties and chemical reactivities of I, especially as NO donor, compared with analogous trans complexes. Among the computational models tested, the B3LYP/ECP28MDF, cc-pVDZ resulted in smaller errors for the geometry of I. The computational data helped clarify the experimental acid-base equilibria and indicated the most favourable site for the second deprotonation, which follows that of the carboxyl group. Furthermore, it showed that by changing the pH it is possible to modulate the electron density of I with deprotonation. The calculated NO bond length and the Ru/NO charge ratio indicated that the predominant canonical structure is [Ru(III)NO], but the Ru-NO bond angles and bond index (b.i.) values were less clear; the angles suggested that [Ru(II)NO(+)] could contribute to the electronic structure of I and b.i. values indicated a contribution from [Ru(IV)NO(-)]. Considering that some experimental data are consistent with a [Ru(II)NO(+)] description, while others are in agreement with [Ru(III)NO], the best description for I would be a linear combination of the three canonical forms, with a higher weight for [Ru(II)NO(+)] and [Ru(III)NO].

Genetic Background of Patients from a University Medical Center in Manhattan: Implications for Personalized Medicine

Background: The rapid progress currently being made in genomic science has created interest in potential clinical applications; however, formal translational research has been limited thus far. Studies of population genetics have demonstrated substantial variation in allele frequencies and haplotype structure at loci of medical relevance and the genetic background of patient cohorts may often be complex. Methods and Findings: To describe the heterogeneity in an unselected clinical sample we used the Affymetrix 6.0 gene array chip to genotype self-identified European Americans (N = 326), African Americans (N = 324) and Hispanics (N = 327) from the medical practice of Mount Sinai Medical Center in Manhattan, NY. Additional data from US minority groups and Brazil were used for external comparison. Substantial variation in ancestral origin was observed for both African Americans and Hispanics; data from the latter group overlapped with both Mexican Americans and Brazilians in the external data sets. A pooled analysis of the African Americans and Hispanics from NY demonstrated a broad continuum of ancestral origin making classification by race/ethnicity uninformative. Selected loci harboring variants associated with medical traits and drug response confirmed substantial within-and between-group heterogeneity. Conclusion: As a consequence of these complementary levels of heterogeneity group labels offered no guidance at the individual level. These findings demonstrate the complexity involved in clinical translation of the results from genome-wide association studies and suggest that in the genomic era conventional racial/ethnic labels are of little value.

POPREP: a generic report for population management

Genetic variation provides a basis upon which populations can be genetically improved. Management of animal genetic resources in order to minimize loss of genetic diversity both within and across breeds has recently received attention at different levels, e. g., breed, national and international levels. A major need for sustainable improvement and conservation programs is accurate estimates of population parameters, such as rate of inbreeding and effective population size. A software system (POPREP) is presented that automatically generates a typeset report. Key parameters for population management, such as age structure, generation interval, variance in family size, rate of inbreeding, and effective population size form the core part of this report. The report includes a default text that describes definition, computation and meaning of the various parameters. The report is summarized in two pdf files, named Population Structure and Pedigree Analysis Reports. In addition, results (e. g., individual inbreeding coefficients, rate of inbreeding and effective population size) are stored in comma-separate-values files that are available for further processing. Pedigree data from eight livestock breeds from different species and countries were used to describe the potential of POPREP and to highlight areas for further research.

Polarization effects in molecular dynamics simulations of glass-formers Ca(NO(3))(2)center dot nH(2)O, n=4, 6, and 8

Thermodynamics, equilibrium structure, and dynamics of glass-forming liquids Ca(NO(3))(2)center dot nH(2)O, n=4, 6, and 8, have been investigated by molecular dynamics (MD) simulations. A polarizable model was considered for H(2)O and NO(3)- on the basis of previous fluctuating charge models for pure water and the molten salt 2Ca(NO(3))(2)center dot 3KNO(3). Similar thermodynamic properties have been obtained with nonpolarizable and polarizable models. The glass transition temperature, T(g), estimated from MD simulations was dependent on polarization, in particular the dependence of T(g) with electrolyte concentration. Significant polarization effects on equilibrium structure were observed in cation-cation, cation-anion, and water-water structures. Polarization increases the diffusion coefficient of H(2)O, but does not change significantly the diffusion coefficients of ions. Viscosity decreases upon inclusion of polarization, but the conductivity calculated with the polarizable model is smaller than the nonpolarizable model because polarization enhances anion-cation interactions.

Fragility and glassy dynamics of 2Ca(NO(3))(2)center dot 3KNO(3) under pressure: Molecular dynamics simulations

Molecular dynamics simulations of the glass-forming liquid 2Ca(NO(3))(2)center dot 3KNO(3) (CKN) were performed from high temperature liquid states down to low temperature glassy states at six different pressures from 10(-4) to 5.0 GPa. The temperature dependence of the structural relaxation time indicates that the fragility of liquid CKN changes with pressure. In line with recent proposal [Scopigno , Science 302, 849 (2003)], the change on liquid fragility is followed by a proportional change of the nonergodicity factor of the corresponding glass at low temperature. (c) 2008 American Institute of Physics.

Soil organic carbon and fertility interactions affected by a tillage chronosequence in a Brazilian Oxisol

No-till (NT) adoption is an essential tool for development of sustainable agricultural systems, and how NT affects the soil organic C (SOC) dynamics is a key component of these systems. The effect of a plow tillage (PT) and NT age chronosequence on SOC concentration and interactions with soil fertility were assessed in a variable charge Oxisol, located in the South Center quadrant of Parana State, Brazil (50 degrees 23`W and 24 degrees 36`S). The chronosequence consisted of the following six sites: (i) native field (NF); (ii) PT of the native field (PNF-1) involving conversion of natural vegetation to cropland; (iii) NT for 10 years (NT-10); (iv) NT for 20 years (NT-20); (v) NT for 22 years (NT-22); and (vi) conventional tillage for 22 years (CT-22) involving PT with one disking after summer harvest and one after winter harvest to 20 cm depth plus two harrow disking. Soil samples were collected from five depths (0-2.5; 2.5-5; 5-10; 10-20; and 20-40 cm) and SOC, pH (in H(2)O and KCl), Delta pH, potential acidity, exchangeable bases, and cation exchangeable capacity (CEC) were measured. An increase in SOC concentration positively affected the pH, the negative charge and the CEC and negatively impacted potential acidity. Regression analyses indicated a close relationship between the SOC concentration and other parameters measured in this study. The regression fitted between SOC concentration and CEC showed a close relationship. There was an increase in negative charge and CEC with increase in SOC concentration: CEC increased by 0.37 cmol(c) kg(-1) for every g of C kg(-1) soil. The ratio of ECEC:SOC was 0.23 cmol(c) kg(-1) for NF and increased to 0.49 cmol(c) kg(-1) for NT-22. The rates of P and K for 0-10 cm depth increased by 9.66 kg ha(-1) yr(-1) and 17.93 kg ha(-1) yr(-1), respectively, with NF as a base line. The data presented support the conclusion that long-term NT is a useful strategy for improving fertility of soils with variable charge. (C) 2008 Elsevier B.V. All rights reserved.

Wavelet analysis of MODIS time series to detect expansion and intensification of row-crop agriculture in Brazil

Since 2000, the southwestern Brazilian Amazon has undergone a rapid transformation from natural vegetation and pastures to row-crop agricultural with the potential to affect regional biogeochemistry. The goals of this research are to assess wavelet algorithms applied to MODIS time series to determine expansion of row-crops and intensification of the number of crops grown. MODIS provides data from February 2000 to present, a period of agricultural expansion and intensification in the southwestern Brazilian Amazon. We have selected a study area near Comodoro, Mato Grosso because of the rapid growth of row-crop agriculture and availability of ground truth data of agricultural land-use history. We used a 90% power wavelet transform to create a wavelet-smoothed time series for five years of MODIS EVI data. From this wavelet-smoothed time series we determine characteristic phenology of single and double crops. We estimate that over 3200 km(2) were converted from native vegetation and pasture to row-crop agriculture from 2000 to 2005 in our study area encompassing 40,000 km(2). We observe an increase of 2000 km(2) of agricultural intensification, where areas of single crops were converted to double crops during the study period. (C) 2007 Elsevier Inc. All rights reserved.

Biofuels and Sustainable Energy Development in Brazil

Through the assessment of three decades of the Alcohol Program in Brazil, the paper shows that adequate public policies regarding biomass production can deliver direct benefits like energy security improvement, foreign exchange savings, and local employment generation, reduced urban air pollution and avoided CO(2) emissions. Moreover, the paper shows that Brazilian produced ethanol has faced economies of scale, technical progress and productivity gains and is no longer dependent on subsidies to be competitive. The paper also examines the potential in Brazil for fostering other biofuels, namely biodiesel obtained from vegetable oils, as well as their implications on sustainable energy development. (C) 2011 Elsevier Ltd. All rights reserved.

Forest-related partnerships in Brazilian Amazonia: There is more to sustainable forest management than reduced impact logging

There is more to sustainable forest management than reduced impact logging. Partnerships between multiple actors are needed in order to create the institutional context for good forest governance and sustainable forest management and stimulate the necessary local community involvement. The idea behind this is that the parties would be able to achieve more jointly than on their own by combining assets, knowledge, skills and political power of actors at different levels of scale. This article aims to demonstrate by example the nature and variety of forest-related partnerships in Brazilian Amazonia. Based on the lessons learned from these cases and the authors` experience, the principal characteristics of successful partnerships are described, with a focus on political and socioeconomic aspects. These characteristics include fairly negotiated partnership objectives, the active involvement of the public sector as well as impartial brokers, equitable and cost-effective institutional arrangements, sufficient and equitably shared benefits for all the parties involved, addressing socioeconomic drawbacks, and taking measures to maintain sustainable exploitation levels. The authors argue that, in addition to product-oriented partnerships which focus on sustainable forest management, there is also a need for politically oriented partnerships based on civil society coalitions. The watchdog function of these politically oriented partnerships, their awareness-raising campaigns regarding detrimental policies and practices, and advocacy for good forest governance are essential for the creation of the appropriate legal and political framework for sustainable forest management. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis of Nb(2)O(5)center dot nH(2)O nanoparticles by water-in-oil microemulsion

Hydrous niobium oxide (Nb(2)O(5)center dot nH(2)O) nanoparticles had been Successfully prepared by water-in-oil microemulsion. They were characterized by X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), BET surface area measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the nanoparticle was exactly Nb(2)O(5)center dot nH(2)O with spherical shape. Their BET surface area was 60 m(2) g(-1). XRD results showed that Nb(2)O(5)center dot nH(2)O nanoparticles with crystallite size in nanometer scale were formed. The crystallinity and crystallity size increased with increasing annealing temperature. TT-phase of Nb(2)O(5) was obtained when the sample is annealed at 550 degrees C. (C) 2009 Elsevier B.V. All rights reserved.