Salmonella spp. in low water activity food: Occurrence,survival mechanisms,and thermoresistance

The occurrence of disease outbreaks involving low-water-activity (a_w) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so-called low-water-activity foods and the salmonellosis outbreaks involving them.     

Differentiation in the fertility of Inceptisols as related to land use in the upper Solimões river region, western Amazon

The Upper Solimões river region, western Amazon, is the homeland of indigenous populations and contains small-scale agricultural systems that are important for biodiversity conservation. Although traditional slash-and-burn agriculture is being practiced over many years, deforestation there is relatively small compared to other Amazon regions. Pastures are restricted to the vicinity of cities and do not spread to the small communities along the river. Inceptisols are the main soil order (>90%) in the area and have unique attributes including high Al content and high cation exchange capacity (CEC) due to the enrichment of the clay fraction with 2:1 secondary aluminosilicates. Despite its importance, few studies have focussed on this soil order when considering land use effects on the fertility of Amazon soils. Thus, the objective of this study was to evaluate changes in soil fertility of representative land use systems (LUSs) in the Upper Solimões region, namely: primary rainforest, old secondary forest, young secondary forest, agroforestry, pasture and agriculture. LUSs were significantly differentiated by the chemical attributes of their topsoil (0-20 cm). Secondary forests presented soil chemical attributes more similar to primary rainforest areas, while pastures exhibited the highest dissimilarity from all the other LUSs. As a whole, soil chemical changes among Inceptisols dominated LUSs showed patterns that were distinct from those reported from other Amazon soils like Oxisols and Ultisols. This is probably related to the presence of high-activity clays enriched in exchangeable aluminum that heavily influenced the soil chemical reactions over the expected importance of organic matter found in most studies conducted over Oxisol and Ultisol.     

Dynamics of residue decomposition in the field in a dryland rotation under Mediterranean climate conditions in southern Spain

With the aim of assessing the benefits of crop remains left on the soil surface, a study was carried out on the decomposition and characteristics of residue deposited on a clay soil in southern Spain during the agricultural seasons of 2001/02, 2002/03 and 2003/04, in which a legume-cereal-sunflower rotation was followed. Each of the residues studied possessed a characteristic justifying its inclusion in the rotation. The legume residue (Pisum sativum L. cv. Ideal) supplied the highest amount of nitrogen to the soil since, throughout its decomposition cycle, it lost 76.6% of its initial content in nitrogen, compared to the 48 and 56% of N released by wheat residues (Triticum durum L. cv. Amilcar) and sunflower (Helianthus annus L. cv. Sanbro), respectively. At the beginning of its decomposition cycle, the wheat residue had the lowest mass, and gave the most cover, with values of 65%, which was 8.6 and 20.2% more than the cover estimated for the pea and sunflower residues, respectively. The sunflower residue lasted longest, only losing 18% of its initial cover over 109 days of decomposition, compared to 47% for wheat and 53% for pea. The amount of carbon released was similar for the three residues and was around 500 kg ha⁻¹. The straw decomposition rates under our conditions indicate that the residue of the most common crops in the area under dry farming makes protection possible during the intercrop period.     

Behavior of materials for earth and rockfill dams: Perspective from unsaturated soil mechanics

The basis of the design of earth and rockfill dams is focused on ensuring the stability of the structure under a set of conditions expected to occur during its life. Combined mechanical and hydraulic conditions must be considered since pore pressures develop during construction, after impoundment and in drawdown. Other instability phenomena caused by transient flow and internal erosion must be considered. The prediction of the hydromechanical behavior of traditional and non-traditional materials used in the construction of dams is therefore fundamental. The materials used for dam’s construction cover a wide range from clayey materials to rockfill. In a broad sense they are compacted materials and therefore unsaturated materials. A summary of the current level of knowledge on the behavior of traditional materials used in the construction of dams is presented in the paper. Regular compacted materials (with a significant clay fraction), rockfill and compacted soft rocks are studied with more detail. The latter are non-traditional materials. They are analysed because their use, as well as the use of mixtures of soil and rock, is becoming more necessary for sustainability reasons.     

EXTRACTION OF IRON(II) BY 2-(2'-THIAZOLYLAZO)-4,6-DIMETHYLPHENOL AND 2-(4',5'-DIMETHYL-2'-THIAZOLYLAZO)-4,6-DIMETHYLPHENOL

The extraction of Fe(II) from 0.1M NaClO₄. by 2-(2'-thiazolylazo)-4,6-dimethylphenol (TADMP) and 2-(4 ', 5'-dimethy1-2’-thiazolylazo)-4,6-dimethylphenol (DMTADMP) dissolved in chloroform has been studied by distribution methods. The experimental data, treated by both graphical and numerical methods, may be explained by assuming the formation of the species FeRClO₄. (logK₁₀₁₁ = 7.58±0.09 and 9.58±0.10) and FeR₂ logK₁₀₂₀. = 14.31±0.22 and 15.32±0.18) for Fe(II)-TADMP and Fefll)-DMTADMP systems, respectively.     

Optimal green tax reforms yielding double dividend

In an stylized endogenous growth economy with a negative externality created by CO2 emissions and in which abatement activities are made by private firms, we find a wide range of dynamically feasible green tax reforms yielding the double dividend without any need to assume a complex production structure or tax system, or a variety of externalities in production. As a remarkable finding, we obtain certain scenarios in which increasing the emissions tax up to the Pigouvian level and removing completely the income tax is dynamically feasible and, also, it is the second-best reform. Hence, as a difference to previous literature, in these scenarios the first-best tax mix is implementable, allowing for the elimination of both environmental and non-environmental inefficiencies. Our result arises because of the consideration of public debt issuing and the management of the government budget balance with an intertemporal perspective. The result is obtained for an intermediate range of environmental bearing in preferences, the valid range being contingent on the pre-existing income tax rate. The type of tax reform that we propose could also be implemented for different energy taxes.