Hidrocarbonetos policíclicos aromáticos em sedimentos de fundo do estuário do rio Potengi, região da grande Natal (RN): implicações ambientais

Estuaries are environments prone to the input of chemical pollutants of various kinds and origins, including polycyclic aromatic hydrocarbons (PAHs). Anthropogenic PAHs may have two possible sources: pyrolytic (with four or more aromatic rings and low degree of alkylation) and petrogenic (with two and three aromatic rings and high degree of alkylation). This study aimed to evaluate the levels, distribution and possible sources of polycyclic aromatic hydrocarbons in the estuary of the Potengi river, Natal, Brazil. Samples of bottom sediments were collected in the final 12 km of the estuary until its mouth to the sea, where the urbanization of the Great Natal is more concentrated. Sampling was performed on 12 cross sections, with three stations each, totaling 36 samples, identified as T1 to T36. The non alkylated and alkylated PAHs were analyzed by gas chromatography coupled to mass spectrometry (GC / MS). PAHs were detected in all 36 stations with total concentration on each varying 174-109407 ng g-1. These values are comparable to those of several estuarine regions worldwide with high anthropogenic influence, suggesting the record of diffuse contamination installed in the estuary. PAHs profiles were similar for most stations. In 32 of the 36 stations, low molecular weight PAHs (with 2 and 3 ring: naphthalene, phenanthrene and their alkylated homologues) prevailed, which ranged from 54% to 100% of the total PAH, indicating that leaks, spills and combustion fuels are the dominant source of PAH pollution in the estuary. The level of contamination by PAHs in most stations suggests that there is potential risk of occasional adverse biological effects, but in some stations adverse impacts on the biota may occur frequently. The diagnostic ratios could differentiate sources of PAHs in sediments of the estuary, which were divided into three groups: petrogenic, pyrolytic and mixing of sources. The urban concentration of the Great Natal and the various industrial activities associated with it can be blamed as potential sources of PAHs in bottom sediments of the estuary studied. The data presented highlight the need to control the causes of existing pollution in the estuary

Avaliação preliminar da contaminação por BTEX, em água subterrânea de poços tubulares, no município de Natal-RN

Among the different types of pollutants typically attributed to human activities, the petroleum products are one of the most important because of its toxic potential. This toxicity is attributed to the presence of substances such as benzene and its derivatives are very toxic to the central nervous system of man, with chronic toxicity, even in small concentrations. The area chosen for study was the city of Natal, capital of Rio Grande do Norte, where samples were collected in six different areas in the city, comprising 10 wells located in the urban area, being carried out in three distinct periods March/2009, December / June/2010 and 2009, and were evaluated for contamination by volatile hydrocarbons (BTEX - benzene, toluene, ethylbenzene and xylenes), so this work aimed to assess the quality of groundwater wells that supply funding for public supply and trade in the urban area of the city of Natal, in Rio Grande do Norte, contributing to the environmental assessment of the municipality. The analysis of BTEX in water was performed according to EPA Method 8021b. Was used the technique of headspace (TriPlus TP100) coupled to high resolution gas chromatography with selective photoionization detector (PID) and flame ionization (FID) - model Trace GC Ultra, Thermo Electron Corporation brand. The procedure adopted allowed the detection of concentrations of the order of μg.L-1. Data analysis with respect to BTEX in groundwater in the area monitored so far, shows that water quality is still preserved, because it exceeds the limits imposed by the potability Resolution CONAMA Nº. 396, April 2008

Evaluation of Th and U contamination in the CUORE experiment using a delayed coincidence analysis

The discovery of the neutrino mass is a direct evidence of new physics. Several questions arise from this observation, regarding the mechanism originating the neutrino masses and their hierarchy, the violation of lepton number conservation and the generation of the baryon asymmetry. These questions can be addressed by the experimental search for neutrinoless double beta (0\nu\beta\beta) decay, a nuclear decay consisting of two simultaneous beta emissions without the emission of two antineutrinos. 0\nu\beta\beta decay is possible only if neutrinos are identical to antineutrinos, namely if they are Majorana particles. Several experiments are searching for 0\nu\beta\beta decay. Among these, CUORE is employing 130Te embedded in TeO_2 bolometric crystals. It needs to have an accurate understanding of the background contribution in the energy region around the Q-value of 130Te. One of the main contributions is given by particles from the decay chains of contaminating nuclei (232Th, 235-238U) present in the active crystals or in the support structure. This thesis uses the 1 ton yr CUORE data to study these contamination by looking for events belonging to sub-chains of the Th and U decay chains and reconstructing their energy and time difference distributions in a delayed coincidence analysis. These results in combination with studies on the simulated data are then used to evaluate the contaminations. This is the first time this analysis is applied to the CUORE data and this thesis highlights the feasibility of it while providing a starting point for further studies. A part of the obtained results agrees with ones from previous analysis, demonstrating that delayed coincidence searches might improve the understanding of the CUORE experiment background. This kind of delayed coincidence analysis can also be reused in the future once the, CUORE upgrade, CUPID data will be ready to be analyzed, with the aim of improving the sensitivity to the 0\nu\beta\beta decay of 100Mo.

Contaminação de águas subterrâneas por pesticidas: avaliação preliminar

A discussion about groundwater contamination is presented in this work. Contamination by agricultural activity, more specifically by pesticides is emphasized. Indirect and direct estimates could be used to predict pesticide behavior in soil, and consequently, to evaluate the potential of groundwater contamination. These results could be applied to advise about the possibility of groundwater contamination by pesticides, and to provide subsidies for making decisions more quickly and efficiently.

Distinguishing post-AGB impostors in a sample of pre-main sequence stars

Context. A sample of 27 sources, cataloged as pre-main sequence stars by the Pico dos Dias Survey (PDS), is analyzed to investigate a possible contamination by post-AGB stars. The far-infrared excess due to dust present in the circumstellar envelope is typical of both categories: young stars and objects that have already left the main sequence and are suffering severe mass loss. Aims. The two known post-AGB stars in our sample inspired us to seek for other very likely or possible post-AGB objects among PDS sources previously suggested to be Herbig Ae/Be stars, by revisiting the observational database of this sample. Methods. In a comparative study with well known post-AGBs, several characteristics were evaluated: (i) parameters related to the circumstellar emission; (ii) spatial distribution to verify the background contribution from dark clouds; (iii) spectral features; and (iv) optical and infrared colors. Results. These characteristics suggest that seven objects of the studied sample are very likely post-AGBs, five are possible post-AGBs, eight are unlikely post-AGBs, and the nature of seven objects remains unclear.

Endophytic and entomopathogenic strains of Beauveria sp to control the bovine tick Rhipicephalus (Boophilus) microplus

Pathogenicity of strains of the entomopathogenic fungus Beauveria bassiana and endophytic strains of Beauveria sp against the bovine tick Rhipicephalus (Boophilus) microplus was tested in laboratory bioassays and under field conditions. Suspensions containing 10(5), 10(7) and 10(9) conidia/mL were prepared of each fungal strain for laboratory bioassays. The ticks were maintained at 28 degrees C, 90 +/- 5% relative humidity, and the following variables were evaluated: initial female weight, egg weight, hatching percentage, reproductive efficiency, and percentage control. For tests under field conditions, a Beauveria suspension containing 10(6) conidia/mL was sprayed on tick-infested cows. After 72 h, the ticks were collected to estimate mortality under field conditions. Laboratory bioassays showed a mortality of 20 to 50% of the ticks seven days after inoculation with 10(7) Beauveria conidia/mL. Under field conditions 10(6) Beauveria conidia/mL induced 18-32% mortality. All Beauveria strains were effective in biological control of R. (Boophilus) microplus under laboratory and field test conditions. This is the first demonstration that endophytic fungi can be used for biological control of the cattle tick; this could help reduce environmental contamination by diminishing the need for chemical acaricides. Two endophytic strains were isolated from maize leaves and characterized by molecular sequencing of 5.8S rDNA ITS1 and ITS2 and morphological analyses of conidia. We found that these two endophytic Beauveria isolates, designated B95 and B157, are close to Beauveria amorpha.

IS ORDINARY ELECTRIC DRILLS` VENTING PORT A POTENTIAL SOURCE OF SURGICAL INFECTION?

Objective: To evaluate the potential risk of surgical contamination by the venting port of ordinary electric drills (ED) employed in orthopaedic surgeries. Materials and Methods: an experimental laboratory, randomized study was developed to analyze EDs in surgical practice and new cleaned and sterilized equipment, which were contaminated with Bacillus atrophaeus spores at a concentration of 84 X 10(6) UFC. The air generated by the engine of each drill was collected and cultivated on sterile agar plates. Results: Positive culture was identified in two ED in surgical practice, as well as a positive culture to Bacillus atrophaeus with 1 CFU growth (1, 19 X 10(-8)). Conclusion: In the conditions of the experiment, the air generated by the venting port of the ED`s engine does not consist of a source of contamination for the surgical site.

Advanced process of microbiological control of wastewater in combined system of disinfection with UV radiation

The purpose of this study was to present a methodology with superior efficiency for inactivating pathogenic indicators commonly found in domestic sewage. The adopted method was based on synergistic effect resulting from the introduction of a UV radiation pre-disinfection stage of sewage followed by secondary treatment. A pilot unit was installed in the sewage treatment plant of the University of Sao Paulo to simulate the combined system in full-scale operational conditions. Its performance was evaluated through microbiological examinations for determining Escherichia coli, total coliforms and coliphages. The application of UV radiation at 5.1mW/cm(2) for 10 s of exposure in the first disinfection stage was enough to reduce the surviving number of E. coli around 100 times, in comparison to the conventional method. Therefore, based on experimental data, it is possible to conclude that combining treatment and pre-disinfection stage is an effective potential technique to produce effluents with lower degree of contamination by pathogenic organisms.

Lead in saliva from lead-exposed and unexposed children

Introduction: Whole blood is used for diagnosis of lead exposure. A non-invasive method to obtain samples for the biomonitoring of lead contamination has become a necessity. This study 1) compares the lead content in whole saliva samples (Pb-saliva) of children from a city with no reported lead contamination (Ribeirao Preto, Sao Paulo State, Brazil) and children of a region notoriously contaminated with lead (Bauru, Sao Paulo State, Brazil), and 2) correlates Pb-saliva with the lead content in the enamel microbiopsy samples (Pb-enamel) in the case of these two populations. Methods: From a population of our previous study that had included 247 children (4- to 6-year-old) from Ribeirao Preto, and 26 children from Bauru, Pb-saliva was analyzed in 125 children from Ribeirdo Preto and 19 children from Bauru by inductively coupled plasma mass spectrometry (ICPMS). To correlate Pb-saliva with Pb-enamel, we used Pb-enamel data obtained in our previous study. The Mann-Whitney test was employed to compare the Pb-saliva data of the two cities. Pb-saliva and Pb-enamel values were then Log(10) transformed to normalize data, and Pb-saliva and Pb-enamel were correlated using Pearson`s correlation coefficient. Results: Median Pb-saliva from the Ribeirao Preto population (1.64 mu g/L) and the Bauru population (5.85 mu g/L) were statistically different (p<0.0001). Pearson`s correlation coefficient for Log(10) Pb-saliva versus Log(10) Pb-enamel was 0.15 (p=0.08) for Ribeirao Preto and 0.38 (p=0.11) for Bauru. Conclusions: A clear relationship between Pb-saliva and environmental contamination by lead is shown. Further studies on Pb-saliva should be undertaken to elucidate the usefulness of saliva as a biomarker of lead exposure, particularly in children. (C) 2008 Elsevier B.V. All rights reserved.

Use of Carnobacterium maltaromaticum cultures and hydroalcoholic extract of Lippia sidoides Cham. against Listeria monocytogenes in fish model systems

Minimally processed refrigerated ready-to-eat fishes may offer health risk of severe infection to susceptible individuals due to contamination by the psychrotolerant bacterium L monocytogenes. In this work, inhibition of L monocytogenes by a plant extract and lactic acid bacteria (IAB) was studied in model fish systems kept at 5 degrees C for 35 days. For that, fillets of tropical fish ""surubim"" (Pseudoplatystoma sp.) and hydroalcoholic extract of the plant Lippia sidoides Cham. (""alecrim pimenta"") were used. Fish peptone broth (FPB), ""surubim"" broth and ""surubim"" homogenate were inoculated with combinations of L monocytogenes and bacteriocin-producing Carnobacterium maltaromaticum (C2 and A9b(+)) and non bacteriocin-producing C. maltaromaticum (A9b(-)), in the presence or absence of extract of ""alecrim pimenta"" (EAP). In all model systems, monocultures of L monocytogenes and carnobacteria reached final populations >= 10(8) CFU/ml after 35 days, except for L monocytogenes in ""surubim"" homogenate (10(4) CFU/ml). In FPB, EAP alone and combined with cultures of LAB inhibited L monocytogenes but carnobacteria without EAP were only weakly antilisterial. In ""surubim"" broth, EAP alone did not prevent L monocytogenes growth but cultures of carnobacteria combined or not with EAP inhibited L monocytogenes, with more pronounced effect being observed for C maltaromaticum C2, which produced bacteriocin. In ""surubim"" homogenate, EAP alone and combined with cultures of C. maltaromaticum A9b(-) and A9b(+) were strongly inhibitory to L monocytogenes, while C maltaromaticum C2 with EAP caused transient inhibition of L monocytogenes. No significant inhibition of L monocytogenes was observed for carnobacteria in ""surubim"" homogenate without EAP. In conclusion, it was observed that the use of EAP and cultures of carnobacteria have potential to inhibit L monocytogenes in fish systems and the applications should be carefully studied, considering the influence of food matrix. (c) 2011 Elsevier B.V. All rights reserved.

Exposure to contaminated water: perceptions and practices in a neighborhood in the city of Manaus, Brazil

Objective. To investigate the modes of water supply and the perception concerning the problems caused by this water among residents of a neighborhood without public supply of water, settled in an area previously used as a garbage dump in the city of Manaus, Brazil. Methods. One hundred and sixty-two semi-structured household interviews were conducted. In addition, a focal group with teachers from a local public school and a meeting with residents were held. The instruments employed focused on the perception and modes of water use and on the process of exposure to chemical contaminants through water. Results. Untreated well water was used by most families. This water was considered to be ""good"" by 64.8% of the individuals interviewed. Most residents (88.3%) declared knowledge about the garbage dump. Of these, 77.6% stated that the garbage dump caused health and environmental problems. However, qualitative analysis of the responses revealed that the residents were not aware of contamination by chemical elements or of the consequences of such contamination. The activities carried out with teachers revealed that they were partially aware of the problem, but did not design interventions to address the issue. In a meeting with neighborhood residents, the presence of social activism concerning the problem was identified, but it did not extend beyond the neighborhood or reach governmental spheres. Conclusions. The study identified a situation of critical exposure that tends to be maintained as a result of misperceptions and lack of social mobilization. The dissemination of research results to teachers and residents was useful to empower subjects.

Chemical treatment of Escherichia coli. II. Direct extraction of recombinant protein from cytoplasmic inclusion bodies in intact cells

A method is presented for the direct extraction of the recombinant protein Long-R-3-IGF-I from inclusion bodies located in the cytoplasm of intact Escherichia coli cells. Chemical treatment with 6M urea, 3 mM EDTA, and 20 mM dithiothreitol (DTT) at pH 9.0 proved an effective combination for extracting recombinant protein from intact cells. Comparable levels of Long-R-3-IGF-I were recovered by direct extraction as achieved by in vitro dissolution following mechanical disruption. However, the purity of directly extracted recombinant protein was lower due to contamination by bacterial cell components. The kinetics of direct extraction are described using a first-order equation with the time constant of 3 min. Urea appears important for permeabilization of the cell and dissolution of the inclusion body. Conversely, EDTA is involved in permeabilization of the cell wall and DTT enhances protein release. pH proved to be important with lower levels of protein release achieved at low pH values (

Cellular origin of chlorinated diketopiperazines in the dictyoceratid sponge Dysidea herbacea (Keller)

The tropical marine sponge Dysidea herbacea (Keller) contains the filamentous unicellular cyanobacterium Oscillatoria spongeliae (Schulze) Hauck as an endosymbiont, plus numerous bacteria, both intracellular and extracellular. Archaeocytes and choanocytes are the major sponge cell types present. Density gradient centrifugation of glutaraldehyde-fixed cells with Percoll as the support medium has been used to separate the cyanobacterial symbiont from the sponge cells on the basis of their differing densities. The protocol also has the advantage of separating broken from intact cells of O. spongeliae. The lighter cell preparations contain archaeocytes and choanocytes together with damaged cyanobacterial cells, whereas heavier cell preparations contain intact cyanobacterial cells, with less than 1% contamination by sponge cells. Gas chromatography/mass spectrometry analysis has revealed that the terpene spirodysin is concentrated in preparations containing archaeocytes and choanocytes, whereas nuclear magnetic resonance analysis of the symbiont cell preparations has shown that they usually contain the chlorinated diketopiperazines, dihydrodysamide C and didechlorodihydrodysamide C, which are the characteristic metabolites of the sponge/symbiont association. However, one symbiont preparation, partitioned by a second Percoll gradient, has been found to be devoid of chlorinated diketopiperazines. The capability to synthesize secondary metabolites may depend on the physiological state of the symbiont; alternatively, there may be two closely related cyanobacterial strains within the sponge tissue.

Modelling solute transport in structured soils: Performance evaluation of the ADR and TRM models

The movement of chemicals through the soil to the groundwater or discharged to surface waters represents a degradation of these resources. In many cases, serious human and stock health implications are associated with this form of pollution. The chemicals of interest include nutrients, pesticides, salts, and industrial wastes. Recent studies have shown that current models and methods do not adequately describe the leaching of nutrients through soil, often underestimating the risk of groundwater contamination by surface-applied chemicals, and overestimating the concentration of resident solutes. This inaccuracy results primarily from ignoring soil structure and nonequilibrium between soil constituents, water, and solutes. A multiple sample percolation system (MSPS), consisting of 25 individual collection wells, was constructed to study the effects of localized soil heterogeneities on the transport of nutrients (NO3-, Cl-, PO43-) in the vadose zone of an agricultural soil predominantly dominated by clay. Very significant variations in drainage patterns across a small spatial scale were observed tone-way ANOVA, p < 0.001) indicating considerable heterogeneity in water flow patterns and nutrient leaching. Using data collected from the multiple sample percolation experiments, this paper compares the performance of two mathematical models for predicting solute transport, the advective-dispersion model with a reaction term (ADR), and a two-region preferential flow model (TRM) suitable for modelling nonequilibrium transport. These results have implications for modelling solute transport and predicting nutrient loading on a larger scale. (C) 2001 Elsevier Science Ltd. All rights reserved.

Directed evolution of mammalian cytochrome P450 enzymes involved in xenobiotic metabolism

Directed evolution of cytochrome P450 enzymes represents an attractive means of generating novel catalysts for specialized applications. Xenobiotic-metabolizing P450s are particularly well suited to this approach due to their inherent wide substrate specificity. In the present study, a novel method for DNA shuffling was developed using an initial restriction enzyme digestion step, followed by elimination of long parental sequences by size-selective filtration. P450 2C forms were subjected to a single round of shuffling then coexpressed with reductase in E. coli. A sample (54 clones) of the resultant library was assessed for sequence diversity, hemo- and apoprotein expression, and activity towards the substrate indole. All mutants showed a different RFLP pattern compared to all parents, suggesting that the library was free from contamination by parental forms. Haemoprotein expression was detectable in 45/54 (83%) of the mutants sampled. Indigo production was less than or comparable to the activities of one or more of the parental P450s, but three mutants showed indirubin production in excess of that seen with any parental form, representing a gain of function. In conclusion, a method is presented for the effective shuffling of P450 sequences to generate diverse libraries of mutant P450s containing a high proportion of correctly folded hemoprotein, and minimal contamination with parental forms.