Indicadores ecotoxicológicos para águas de consumo humano.

Testes de toxicidade utilizando organismos vivos, são de alta vantagem em termos de custo e benefício. Mostram com rapidez a qualidade das amostras testadas quanto a toxicidade. Utiliza-se organismos padronizados, de vários níveis tróficos, os quais respondem de maneira diversa aos diversos componentes das amostras ambientais. A qualidade de águas tratadas por ETAs das cidades de Limeira e Piracicaba, SP, foram avaliadas quanto a toxicidade para o microcrustáceo Daphnia magna, celenterado Hydra attenuata, alga Pseudokirchneriella subcapitata e a bactéria Vibrio fischeri . As Daphnias e as algas mostraram se altamente sensíveis a cloração, as Hydras e Vibrio mostraram-se resistentes sendo possível ser realizados testes com águas tratadas e cloradas. O tiossulfato de sódio foi utilizado para precipitar o cloro das amostras cloradas, entretanto precipitou também outras substâncias, diminuindo a toxicidade das águas brutas, sem cloro. Análises de resíduos mostrou a presença de herbicidas e trihalometanos nas amostras de água tratada do rio Corumbataí. O crescimento da alga P.subcapitata foi inibido em concentrações de atrazina de 7 a 10 microgramas L-1, mas não de 3 a 3,7 microgramas g L-1 . Os testes toxicológicos são importantes ferramentas para indicar presença de compostos tóxicos em amostras de água e podem mostrar a qualidade das águas tratadas

Development, uncertainty estimation and application of a LC-MS/MS method for simultaneous determination of acrylamide and 4hydroxy2,5-dimethyl-3(2H)-furanone in baby food.

Acrylamide, a heatgenerated food contaminant, has been associated with neurotoxic effects in humans and was classified under group 2A as a probable human carcinogen by the International Agency Research on Cancer (IARC) [1]. Additionally, hydroxy2,5dimethyl3(2H)furanone (DMHF), a furanic compound, has demonstrated genotoxic effects in vitro as also in vivo [2]. In this study, a new accurate liquid chromatographytandem mass spectrometry method was developed for simultaneous analysis of acrylamide and DMHF in baby food. To the best of our knowledge, this is the first study on DMHF in baby foods as well as pioneer in acrylamide monitoring in baby foods from Brazil. For this, a sample preparation method was optimized, which involves acetonitrile-based extraction, followed by dispersive solidphase extraction (dSPE) using primary and secondary amine sorbent (PSA) and then, a final cleanup of extract by solid phase extraction (SPE). An ACQUITY ultraperformance liquid chromatography (UPLC) system interfaced to a Quattro Premier XE triple quadrupole mass spectrometer with electrospray ionization (ESI) source (WATERS) was employed for analysis. The chromatographic separation was achieved on a C8 column (150 mm x 2.1 mm i.d., 5?m particle size) at 30ºC with a flow rate of 0.2 ml/min, and the injection volume was 20 ?l. The mobile phases consisted of MilliQ water (A) and acetonitrile (B), both containing 0.01% of formic acid, and the elution gradient employed was as follows: 0 min, 5% B? 5 min, 50% B? 5.1 min, 100% B? 6?10 min 5% B, resulting in a total run time of 10 min. Data acquisition was carried out in selective reaction monitoring (SRM) mode employing ESI in positive mode, whose conditions were: capillary voltage 3 KV? temperatures of source at 120°C and desolvation at 400°C and gas flow 500 L/h. The collision energy and cone voltage were 10 and 25 V. The m/z 55 and 44 (acrylamide) and m/z 101 and 83 (DMHF) were used respectively for quantitative and confirmative purposes. As a great result, the optimized sample preparation method provided sufficient removal of potential analytical interfering commonly present in fruitbased matrices, the amino acid valine, without affecting the sensitivity, trueness and precision of the method. Limits of detection (LOD) and quantification (LOQ) of 10 and 20 ?g/kg were obtained for both analytes. Linearity in solventonly and matrixmatched calibration curves was achieved in the range between 10 and 300 ?g/kg, with determination coefficients higher than 0.99. Matrix effects, calculated from slopes obtained for solvent and matrixmatched calibrations, were observed for acrylamide (?45%) and DMHF(?11%). Recoveries between 75 and 115% were obtained for the two studied compounds from blank baby foods spiked at 20 (LOQ), 100 and 200 ?g/kg. Precision, under repeatability and withinlaboratory reproducibility conditions, was verified with RSD values < 20%. In addition, by using data obtained from inhouse validation, was possible to estimate the expanded measurement uncertainty for the levels of acrylamide and DMHF detected in the samples, whose values were lower than 25%. The applicability of proposed analytical method was evaluated by analyzing 20 baby food samples available in Brazilian markets

Kosterlitz-Thouless transition in three-state mixed Potts ferro-antiferromagnets

We study three-state Potts spins on a square lattice, in which all bonds are ferromagnetic along one of the lattice directions, and antiferromagnetic along the other. Numerical transfer-matrix are used, on infinite strips of width $L$ sites, $4 \leq L \leq 14$. Based on the analysis of the ratio of scaled mass gaps (inverse correlation lengths) and scaled domain-wall free energies, we provide strong evidence that a critical (Kosterlitz-Thouless) phase is present, whose upper limit is, in our best estimate, $T_c=0.29 \pm 0.01$. From analysis of the (extremely anisotropic) nature of excitations below $T_c$, we argue that the critical phase extends all the way down to T=0. While domain walls parallel to the ferromagnetic direction are soft for the whole extent of the critical phase, those along the antiferromagnetic direction seem to undergo a softening transition at a finite temperature. Assuming a bulk correlation length varying, for $T>T_c$, as $\xi (T) =a_\xi \exp [ b_\xi (T-T_c)^{-\sigma}]$, $\sigma \simeq 1/2$, we attempt finite-size scaling plots of our finite-width correlation lengths. Our best results are for $T_c=0.50 \pm 0.01$. We propose a scenario in which such inconsistency is attributed to the extreme narrowness of the critical region.Comment: 11 pages, 6 .eps figures, LaTeX with IoP macros, to be published in J Phys

Novel Studies on the \eta' Effective Lagrangian

The effective Lagrangian for \eta' incorporating the effect of the QCD \theta-angle has been developed previously. We revisit this Lagrangian and carry out its canonical quantization with particular attention to the test function spaces of constraints and the topology of the \eta'-field. In this way, we discover a new chirally symmetric coupling of this field to chiral multiplets which involves in particular fermions. This coupling violates P and T symmetries. In a subsequent paper, we will evaluate its contribution to the electric dipole moment (EDM) of fermions. Our motivation is to test whether the use of mixed states restores P and T invariance, so that EDM vanishes. This calculation will be shown to have striking new physical consequences.Comment: 14 pages, 1 figure; V2: NEW TITLE; revised version to be published in JHEP; references adde

Prevalência da infecção pelo Helicobacter pylori em Fortaleza, Ceará

The prevalence of Helicobacter pylori infection was assessed in a randomly selected sample of individuals from low-income community in Fortaleza, Northeastern Brazil. Overall, 384 out of 610 participants (62.9%) were H. pylori positive. A 47.5% infection rate was found in subjects aged six months to 10 years old, increased to 73.3% in subjects aged 11-20 years and then continued to increase with age reaching up to 87% in those over 60 years old. After this age group, the prevalence decreased slightly. The prevalence of infection increased significantly with age (pA prevalência da infecção pelo Helicobacter pylori foi avaliada em amostra randomizada de indivíduos de uma comunidade urbana de baixa renda em Fortaleza, Estado do Ceará. O H. pylori foi detectado em 384 (62.9%) dos 610 participantes. A taxa de infecção foi de 47.5% em indivíduos com seis meses a 10 anos de idade, aumentou para 73.3% entre indivíduos com 11 a 20 anos, e continuou a aumentar com a idade, atingindo 87% naqueles com aproximadamente 60 anos. Após essa idade, a prevalência diminuiu discretamente. A prevalência da infecção aumentou significantemente com a idade (

Efeito da exploração florestal de impacto reduzido sobre a regeneração natural em uma floresta densa de terra firme no município de Paragominas na Amazônia brasileira.

O estudo foi motivado pela escassez de informações sobre a sustentabilidade ecológica da exploração de florestas naturais, em áreas diretamente afetadas pela exploração. O objetivo foi verificar se há diferença florística entre a floresta não-explorada e áreas diretamente afetadas pela exploração, e entre anos pós-exploração, e averiguar a capacidade de recuperação natural da floresta, quanto à estrutura e composição florística anteriores à exploração. Avaliou-se a regeneração natural em três áreas exploradas em diferentes ocasiões (2000, 2003 e 2006), no período de sete anos, na Fazenda Rio Capim, no município de Paragominas, Pará. Os dados foram coletados em clareiras, ramais de arraste primário e secundário, pátio de estocagem e floresta remanescente da exploração, considerando indivíduos entre 2,5 e 10,0 cm de diâmetro. Calculou-se a abundância, índice de diversidade, equitabilidade, similaridade florística. No período de até sete anos após a exploração florestal de impacto reduzido, ocorreram marcantes alterações na composição florística e na abundância de indivíduos com DAP de 2,5-10,0 cm, principalmente nos ramais principais e pátios. Na floresta remanescente, a dinâmica, tanto de espécies quanto de indivíduos, ocorreu mais com espécies tolerantes à sombra, porém nas clareiras, ramais e pátios predominaram as espécies pioneiras. Nos pátios e nos ramais de arraste, o desenvolvimento das plantas foi muito baixo, não permitindo alta abundância de indivíduos com DAP maior que 2,5 cm. A regeneração natural nas áreas abertas pela exploração florestal, embora tenha sofrido influência da floresta remanescente, conta com poucas espécies de alto valor comercial. Portanto, sugere-se que devam ser aplicados tratamentos silviculturais pós-exploratórios para beneficiar mudas de regeneração natural (DAP = 2,5 cm) pré-existentes e sejam realizados enriquecimentos em clareiras para garantir estoque suficiente de espécies comerciais para futuras colheitas