Abstract: Polycyclic aromatic hydrocabons (PAHs) and their nitroderivatives (NPAHs) are ubiquitous in the environment and they are produced in several industrial and combustion processes. Some of these compounds are potent carcinogens/mutagens and their determination in biological samples is an important step for exposure control. A review of the analytical methodologies used for the determination of PAHs and their metabolites in biological samples is presented.

Abstract: The prevalence of antibodies to hepatitis A and B virus was assessed in 3,653 subjects across four regions of Brazil. The anti-HAV and anti-HBc seroprevalence were 64.7% and 7.9%, respectively. The highest anti-HAV (92.8%) and anti-HBc (21.4%) rates were seen in the Northern region. In other regions, anti-HAV seroprevalence over 90% was only reached in the more elderly, indicating an intermediate endemicity and a significantly higher anti-HAV prevalence was seen in the low socioeconomic group between 1-30 years. With respect to anti-HBc seroprevalence an increase was seen in adolescents and there was a significantly higher anti-HBc prevalence in the lower socioeconomic group between 1-20 years. A 3.1% anti-HBc prevalence was seen in one-year-old infants, suggesting a vertical transmission. The major findings of this study indicate that the pre-adolescent and adolescent population in some Brazilian cities are at greatest risk from both hepatitis A and B infection, but for different reasons.

Abstract: This paper deals with the concept of transdisciplinarity in order to propose a comparison between the notions of "field" and "clinic grounds". After discussing the use of the concept of "field" within Psychology, we focus on the issue of clinic and its tuning with contemporary thinking. The idea that clinic is always transdisciplinary is supported by such theoretical contributions as that of Giles Deleuze's philosophy and Humberto Maturana and Francisco Varela's biology of autopoiesis.

Abstract: This paper describes a new approach for establishing power systems scheduled generators outages for maintenance purposes. The time frame considered refers to power systems short-term operations planning horizon (i.e. one month ahead). The paper's main contribution is focused on modeling grid operational constraints, which are dealt with by a DC optimal power flow. The resulting large-scale optimization problem is solved by mixed-integer programming techniques aided by Benders decomposition strategy. The obtained results clearly show that representing transmission influence is essential for the establishment of a sound set of scheduled outages for the system's generators, especially in the case of hydrothermal systems.

Abstract: The role of the breakup process of the weakly bounded light projectile ${}^{9}\mathrm{Be},$ on the near barrier fusion reaction and elastic scattering, is investigated by two different approaches. The fusion cross sections for the ${}^{9}\mathrm{Be}{+}^{64}\mathrm{Zn}$ system were compared with the ones from other similar systems (the ${}^{16}\mathrm{O}{+}^{64}\mathrm{Zn}$ and ${}^{14}\mathrm{N}{+}^{59}\mathrm{Co}).$ The measurement of the elastic scattering for this system was also used to study the threshold anomaly. There are indications that the fusion suppression due to the ${}^{9}\mathrm{Be}$ breakup is not important for the interaction of ${}^{9}\mathrm{Be}$ with this medium mass target.

Abstract: The structures of two new, naturally occurring cytotoxic depsipeptides, tamandarins A and B (1 and 2), are presented. The tamandarins were isolated from an unidentified Brazilian marine ascidian of the family Didemnidae. The structures of the new cytotoxins were assigned by interpretation of FABMS data and by extensive 2D NMR analyses. The absolute configurations of the tamandarins were assigned by acid and alkaline hydrolysis to yield their corresponding amino acids, which were then analyzed as their Marfey derivatives. The cytotoxicity of tamandarin A (1) was evaluated against various human cancer cell lines and shown to be slightly more potent than didemnin B. A qualitative discussion of the conformation of tamandarin A (1) in solution, obtained from NMR J-value data, variable temperature experiments, and NOESY/ROESY data, is included.

Abstract: O conceito de sistema petrolifero agrupa os diversos elementos que controlam a existencia de jazidas de petroleo numa bacia sedimentar. Tal conceito, visualizado numa escala global, parece justificar de maneira adequada as diversas provincias petroliferas conhecidas. A evolucao tectono-sedimentar meso-cenozoica da margem continental brasileira propiciou o desenvolvimento desses elementos-chave, cuja presenca e requisito fundamental a que uma determinada regiao seja atrativa para a prospeccao petrolifera. Merece destaque nesse particular o segmento de aguas profundas da Bacia de Campos, que, na visao contemporânea, representa a porcao mais bem aquinhoada em termos de volumes descobertos de toda a margem brasileira. Em termos historicos, a exploracao de petroleo no Brasil inclui tres grandes fases: o periodo pre-Petrobras, basicamente de atividades pioneiras de reconhecimento; a etapa de exclusividade da Petrobras, onde se vislumbram quatro etapas - 1954/1968: Fase Terrestre, 1969/1974: Fase Maritima/Plataforma Rasa, 1975/1984: Fase Maritima/Plataforma Rasa/Bacia de Campos, e 1985/1997: Fase Maritima/Bacia de Campos/Aguas Profundas, cada uma delas com caracteristicas particulares e responsavel por sucessivos incrementos na reserva petrolifera do Pais, que alcanca hoje cerca de 16 bilhoes de barris de oleo-equivalente; e a fase atual, sob a vigencia da Nova Lei do Petroleo, caracterizada por intensa atividade em que varias companhias nacionais e estrangeiras atuam tanto em areas anteriormente trabalhadas como em desafiadoras novas fronteiras.

Abstract: Cu/ZSM-5 catalysts were characterized by DRS UV–Vis IR spectroscopy, CO chemisorption and NO TPD. The results indicated that the exchange level in Cu 2+ is complete. The oxidation number of copper ions after calcination is 2+, with the formation of isolated Cu 2+ species, CuO and (Cu–O–Cu) 2+ compounds, depending on the pretreatment conditions. It was found that copper atoms are arranged as small clusters, well dispersed in the zeolite framework. The results indicated the active species for catalytic decomposition of NO is Cu 2+ , which can be reduced to Cu + forming Cu + –NO 2 and Cu + –(NO) 2 complexes. The dependence of copper ions state and therefore, the pretreatment are important for the NO decomposition activity due to the formation of the (Cu–O–Cu) 2+ oxocation species, which act as catalytic sites for the disproportionation of NO to N 2 O + NO 2 . Methanol oxidation showed that the activity and selectivity are not dependent on pretreatment temperature, but they are markedly influenced by the acid site distribution. Methanol was inactive for NO reduction, since methanol can not be activated on the NO adsorption sites to form species that are active for NO reduction.

Abstract: Mental models have been approached from a number of different perspectives, from cognitive psychology to philosophy of science and science education. As a result, several definitions have been proposed that emphasise distinct aspects. It has also been suggested that researchers have access to people’s mental models by means of the examination of individuals’ expressed models. We argue that, in order to grasp mental models, a fruitful strategy involves developing two complementary approaches: one that focuses on how mental models are developed and the other one on their key features when people make use of them to think. In particular, we will deal with three basic issues: to what extent can we talk about mental models by examining expressed models? What are the tools individuals make use of in order to build mental models? What are the main features of mental models? Each issue is addressed below, starting from a critical analysis of existing literature so as to suggest and discuss a framework that could help us grasp mental models.

Abstract: This work intends to identify the reasons why people either like or dislike chemistry classes, based on a written questionnaire answered by 157 students of private and public schools. It has a main question - "Do you like to study chemistry? Why?" - and along with others that complement it, we attempt to explore both pupils' school and personal experiences which help them to increase their learning capacities. The answers have given us a very rich piece of discussing material about the like-and-dislike on the study of chemistry mainly about the social interactions in teaching not only this but all other subjects.

Abstract: Electronic and optical characteristic energies of semiconductor quantum rings in the presence of magnetic fields were determined by adopting distinct potential models to describe the ring confinement and considering different geometric confinement parameters defining the quantum ring. It was found that the ground-state energy becomes independent of the ring radius once the internal ring hole is present, because it is the strength of the lateral confinement that determines its subsequent behavior. The optical spectra for large and narrow quantum rings exhibit a set of resonances governed basically by the strength of the radial confinement. The presence of a magnetic field produces a notable enhancement of the resonance intensities.

Abstract: Water samples were collected in Middle Amazonia from the Amazon River, Rio Negro and 17 tributaries of Rio Negro. The analyses consisted of pH, conductivity, and dissolved organic (DOC) measurements, as well as plasma source mass spectrometry (ICP-MS). Factor analysis revealed three factors, which explained 94% of the total variance. A plot of factor scores presented a cluster containing mostly samples from the Rio Negro Basin. Ultrafiltration tests confirmed that organics from the Rio Negro have higher molecular mass than in the Amazon, and that some metals are associated with these compounds. Heavy rare-earth elements (REE) are enriched relative to light REE in the dissolved fraction of most rivers of the Negro Basin; the opposite occurred in suspended matter.

Abstract: Mdx mouse, the animal model of Duchenne muscular dystrophy, lacks dystrophin and develops an X-linked recessive inflammatory myopathy characterized by degeneration of skeletal muscle fibers and connective tissue replacement. The present work aimed to assess whether gender dimorphism in mdx mice would influence skeletal muscle pathology at ages corresponding to main histological changes in the microenvironment of muscular tissue: myonecrosis, regeneration, and fibrosis. At the height of myonecrosis (6 weeks postnatal), skeletal muscles of male mdx mice showed increased sarcolemmal permeability, numerous inflammatory foci, and marked deposition of the extracellular matrix components (ECM) type I collagen and laminin. In contrast, age-matched mdx females showed mild ECM deposition, discrete myonecrosis, but increased numbers of regenerating fibers expressing the satellite cell marker NCAM. In contrast ovariectomized mdx females showed decreased numbers of regenerating fibers. Older (24 and 48 weeks postnatal) mdx females showed extensive fibrosis with increased sarcolemmal permeability and marked deposition of ECM components than corresponding males. These results suggest a role for female hormones in the control of myonecrosis probably by promoting regeneration of muscular tissue and mitigating inflammation especially at ages under the critical influence of sex hormones.

Abstract: The correlation of geophysical data (side-scan sonar and subbottom profiler - 3.5 and 7.0 kHz) has enabled the characterization of the sediment distribution along the southern portion of the Guanabara Bay (Rio de Janeiro - Brazil). Four distinct echocharacter types were recognized: type 1 shows no penetration of the acoustic signal, it is associated with a sandy bottom and with a light gray homogeneous sonograph pattern with sand waves and mega ripples; type 2A presents internal reflectors and the acoustic basement, it is related to a muddy bottom with high content (%) of fine sand and to light gray homogeneous sonograms; type 2B is marked by signal penetration and is related to a sandy bottom with high content (%) of mud and to dark grey homogeneous sonograms; and, finally, type 3 with signal penetration and multiples, it is associated with a muddy bottom with high content (%) of fine sand, and is related to dark gray homogeneous sonograph patterns.

Abstract: Local electronic properties of metallic-semiconducting carbon nanotube heterostructures are investigated by studying the behavior of the one-electron local density of states (LDOS) along the tubes. We determine how these properties change from the metallic to the semiconducting side of a nanotube junction. We show that Friedel oscillations may not always be evident on the metallic side, and we found clear exponential decay of the LDOS on the semiconducting side. The exponential rates of decay as well as the absence of the oscillations are explained in terms of a simple picture that relates the LDOS to the bulk electronic structure of the constituent parts of the heterostructures.

Abstract: The small-world transition is a first-order transition at zero density p of shortcuts, whereby the normalised shortest-path distance = /L undergoes a discontinuity in the thermodynamic limit. On finite systems the apparent transition is shifted by Δp ~ L−d. Equivalently a "persistence size" L* ~ p−1/d can be defined in connection with finite-size effects. Assuming L* ~ p−τ, simple rescaling arguments imply that τ = 1/d. We confirm this result by extensive numerical simulation in one to four dimensions, and argue that τ = 1/d implies that this transition is first order.

Abstract: A theoretical study of shallow-donor states in toroidal GaAs-(Ga,Al)As quantum rings, within the effective-mass approximation and following a variational calculation, is presented. The particular topology of quantum rings is shown to produce interesting confining effects on the impurity states, namely, the effective dimensionality of a quantum ring may increase as it shrinks. The density of impurity states is calculated, and quantum-well wire and quantum-dot regimes are discussed. Also, the effects of an axial magnetic field on free-electron and shallow-donor states are analyzed.

Abstract: We present here the first results of Hg concentrations in three small shark species (Rhizoprionodon lalandei, R. porosus and Mustelus higmani) from the SE Brazilian coast. Mercury concentrations in R. lalandei ranged from 21.5 to 280.0 ng.g-1 dry weight (d.w.) (average 74.6 ng.g-1 d.w.; 17.9 ng.g-1 wet weight). In R. porosus, concentrations ranged from 7.6 to 90.5 ng.g-1 d.w. (average 42.2 ng.g-1 d.w., 9.4 ng.g-1 wet weight), whereas in M. higmani, concentrations ranged from 13.0 to 162.8 ng.g-1 d.w. (average 54.9 ng.g-1 d.w., 13.4 ng.g-1 wet weight). These concentration ranges are very low compared with values reported for other large shark species of the Southwestern Atlantic Ocean. There was a significant positive correlation between Hg concentrations and individual size, suggesting that biomagnification is occurring in these animals.

Abstract: Following the development of PCR methods, molecular techniques have become widely used for detecting genetic variation in natural populations. Most nucleotide changes can be detected by these techniques. Many of these changes probably reflect silent substitutions that are likely to be selectively neutral, making them particularly suitable to population genetic studies. In this paper, we review the published literature on molecular population genetics, with respect to the genome assayed (nuclear, mitochondrial or chloroplast), the organisms studied, the molecular techniques used, and the biological problems addressed. Several molecular techniques are then compared using experimental results obtained from a population genetic study of the Mytilus complex in the North Atlantic and Mediterranean. Finally, the most appropriate theoretical tools to analyse molecular population genetic data are discussed.