Biodegradability of Thermally Aged PHB,PHB-V,and PCL in Soil Compostage

The biodegradability of poly--hydroxybutyrate (PHB), poly--hydroxybutyrate-co-valerate (PHB-V) and poly--caprolactone (PCL) were examined following thermal aging in an oven for 192, 425 and 600 h. Different temperatures, 100, 120 and 140°C for PHB and PHB-V and 30, 40 and 50^oC for PCL were used to assess the influence of this parameter on biodegradation. The biodegradability tests were done in soil compostage at pH 11.0 and involved measuring the residual mass of polymer. Thermal analysis of the polymers was done using a differential scanning calorimeter (DSC). The melting temperature and crystallinity were also determined. Thermal ageing increased the biodegradability only for PHB at 120 and 140^oC, and there was no correlation between crystallinity and the biodegradation of the polymers.     

Solid State Reactions of Potato Starch with Urea and Biuret

Reaction of granular potato starch with urea and biuret resulted in the formation of products, which were soluble neither in cold nor boiling water. The net reaction was a monosubstitution of the hydrogen atom in one hydroxyl group in each D-glucose unit of starch with the either CO–NH₂ or CO–NH–CO–NH₂ moiety, respectively. Properties of the products, particularly these with urea, depended on the mode of reaction. Reactions were carried out in the microwave oven as well as with convection heating. The products retained the granular form of starch but a vast majority of granules were damaged. -Amylolysis of those materials revealed that their susceptibility to the enzyme increasing in the order: starch-amylolysis with simultaneous insolubility in water make these products suitable as ruminant fodder and, eventually, biodegradable material.     

Ontogenic changes of amino acid composition in planktonic crustacean species

Changes in amino acid composition (AAC) during ontogeny of some planktonic crustacean species commonly found in fresh and brackish coastal waters were compared. For these comparisons two calanoid copepods (Eurytemora velox and Calanipeda aquae-dulcis), two cyclopoid copepods (Diacyclops bicuspidatus odessanus and Acanthocyclops robustus) and two Daphnia (Daphnia pulicaria and Daphnia magna) species were selected. A discriminant analysis was performed to determine whether there were significant differences between the AAC of the different stages of each species. Results show gradual changes in AAC during ontogeny of the copepod species. Calanoids showed the greatest differences in AAC between stages, followed by cyclopoids. Gradual changes in AAC were due to the increase in some amino acids such as alanine, valine, glutamic acid, glycine, arginine, proline and tyrosine from nauplii to adults. The latter showed a remarkable increase in all copepod species. In contrast, Daphnia species showed a relatively constant AAC during development, with only minor changes being detected, and not related with ontogeny. Differences in the physico-chemical variables of the lagoons do not seem to be the cause of copepod ontogenic changes in AAC. Data suggest that AAC differences found between stages of copepod species could indicate a gradual change in diet during the life cycle of these copepods.     

Extent of sonochemical degradation and change of toxicity of a pharmaceutical precursor (triphenylphosphine oxide) in water as a function of treatment conditions

The degradation of triphenylphosphine oxide (TPPO) in water, a toxic compound typically found in effluents from the pharmaceutical industry, by means of ultrasonic irradiation at 20 kHz has been investigated with emphasis on the effect of various parameters on conversion and acute toxicity. Experiments were carried out at liquid volumes of 50 and 80 ml, electric power outputs of 125, 187.5 and 250 W, initial TPPO concentrations of 10, 100 and 350 mg/L and temperatures of 5, 20, 35, 50 and 70 degrees C. TPPO conversion was found to increase with increasing power output and decreasing initial concentration and temperature. Measurements of dissolved total carbon showed that liquid-phase degradation by-products were more stable to ultrasonic irradiation than TPPO. Addition of t-butanol as a radical scavenger at a concentration of 1000 mg/L nearly completely suppressed TPPO degradation. Conversely, addition of radical promoters (Fe(2+) ions or H(2)O(2)) had a positive effect on degradation. Acute toxicity to marine bacteria vibrio fischeri was measured before and after ultrasonic irradiation. At the conditions employed in this study, irradiated TPPO samples were always more toxic than TPPO itself with toxicity levels being a function of treatment conditions.     

Radioactivity concentration in liquid and solid phases of scale and sludge generated in the petroleum industry

Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.     

Intake of uranium and radium-226 due to food crops consumption in the phosphate region of Pernambuco--Brazil

The phosphate region located in the Northeast of Brazil covers an area of approximately 150 km long with an average width of 4 km, along the coast of the states of Pernambuco and Paraíba. The inhabitants of this area are exposed to natural radioactivity levels higher than the background values recorded in the literature, mainly due to the presence of uranium and its decay products in the phosphatic sediments. The main aim of this study was to determine the activity concentration of uranium and (226)Ra in foodstuffs cultivated in this area, where the phosphate mineral has been extracted. The activity concentrations found for uranium and (226)Ra in the foodstuffs analyzed varied from 13 to 186 mBq kg(-1) (wet weight), with a mean value of 46 mBq kg(-1) and from 43 to 2209 mBq kg(-1) (wet weight), with a mean value of 358 mBq kg(-1), respectively. The annual intake of these radionuclides, for rural residents, was 7.45 Bq for uranium and 69.3 Bq for (226)Ra.     

Tourists‘ and Locals‘ Preferences Toward Ecotourism Development in the Maya Biosphere Reserve,Guatemala

Ecotourism has been identified as a low impact means to provide income generating opportunities that are complementary to nature conservation as well as the welfare of the local population. The Maya Biosphere Reserve in Peten, Guatemala is one of Central America's largest and most isolated protected areas. And although the area is contains a well-visited archeological site, it has not been developed for ecotourism. In this study choice experiments are used to analyze the preferences toward alternative scenarios of ecotourism of two important stakeholder groups: foreign tourists and educated local residents. Results demonstrate that these two populations of have unequal but similar preference orderings, especially toward: improved national park management and the presence of guides for wildlife viewing. These stakeholder groups had different opinions toward paved access roads and the presence of illegal colonists within the protected area. Both populations favored an entrance fee toward the absence of an entrance fee. These preferences were generally consistent across other socioeconomic indicators. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Evaluation of compliance with national legislation on emissions in Portugal

More than 13 years after publication of the first air quality laws in Portugal and more than 10 years after the publication of the respective emission limits, it seems appropriate to analyze the degree of compliance by the Portuguese manufacturing industry. Using the data from emission measurements made regularly by the Instituto de Soldadura e Qualidade, the only officially accredited laboratory according to standard ISO 17025, I analyzed a set of approximately 400 sources in terms of compliance with the emission limits regarding total suspended particulates, sulfur dioxide, nitrogen oxides, and volatile organic compounds. I evaluated compliance through a nondimensional parameter and plotted it versus the emission flow rate to derive conclusions: the results indicate that emission limits are generally met regarding sulfur dioxide and nitrogen oxides but not for the other pollutants considered in this study. However, noncompliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits, which are being revised at the moment. These alterations will include the exemption of measurements in minor sources.     

Eucalyptus ESTs related to genes for oxidative stress

Oxidative stress generating active oxygen species has been proved to be one of the underlying agents causing tissue injury after the exposure of Eucalyptus (Eucalyptus spp.) plants to a wide variety of stress conditions. The objective of this study was to perform data mining to identify favorable genes and alleles associated with the enzyme systems superoxide dismutase, catalase, peroxidases, and glutathione S-transferase that are related to tolerance for environmental stresses and damage caused by pests, diseases, herbicides, and by weeds themselves. This was undertaken by using the eucalyptus expressed-sequence database (https//forests.esalq.usp.br). The alignment results between amino acid and nucleotide sequences indicated that the studied enzymes were adequately represented in the ESTs database of the FORESTs project.     

A technique for cutting brittle undisturbed lateritic soil block samples

This note describes a technique for cutting undisturbed brittleblock samples into smaller specimens for further geotechnical testing. This technique revealed very useful in dealing with collapsible soils, where the sampling is recommended to be donewith block soil samples. A further use of this technique as an efficient way for sampling collapsible soils is proposed.