Detecção de contaminação de solo por vinhaça através de análise de dados de eletrorresistividade

The vinasse, awaste produced in the proportion of 13 liters for each liter of alcohol. It has a high potential of polluting groundwater and superficial water resources, changes the soil behaviour and can also develop sanilization problems. This work aims to evaluate the efficiency of the DC-resistivity method in detecting and mapping anomalies caused by inappropriate disposal of vinasse in an inactive infiltration tank located at Sepé-Tiarajú settlement of landless agricultural laborers in the Ribeirão Preto region. Besides, as secondary goals, this work aims to characterize the type of anomaly residue as well as to diagnose its influence inside and outside of the limits of the tank. Eleven electrical resistivity tomography profiles were carried out with the dipole-dipole array, 10m of dipoles length and 5 leveis of investigation The geophysical survey enabled us to conclude that the DC-resistivity method is appropriate for mapping the contamination plume caused by intense vinasse disposal and its influence. It enabled also to conclude that the contamination exceeds the tank limits. The vinasse influence can be characterized by low resistivity values between 10 Ohm.m and 90 Ohm.m and its behavior can be compared with the one of the chorume, which is also conductive.

Detecção de contaminantes em espécie bioindicadora (Corbicula fluminea) - Rio Ribeira de Iguape - SP

The study assessed heavy metal concentrations in the tissue samples of Corbiculafluminea, by ICP-OES. In the tissues, average levels of 23.99 µg/g of Cu, 144.21 µg/g of Zn, 0.71 µg/g of Cd, 7.10 µg/g of Cr and 2.41 µg/g of Pb were detected ahowing that this last value is high and above the ANVISA reference (2.00 µg/g) for fish and other products. The results suggest that natural processes occuring in the Ribeira de Iguape River are not sufficient for purification so that metals remain in the water and can accumulate in the trophic chain.

Detecção de estímulos concêntricos mesópicos em crianças surdas e ouvintes

O objetivo deste trabalho foi medir curvas de sensibilidade ao contraste de 10 crianças ouvintes e de 10 crianças com surdez pré-lingual, de 7 a 12 anos, utilizando frequências radiais circularmente concêntricas (FSCr) de 0,25-2,0 cpg em níveis baixos de luminância (0,7 cd/m²). Todos os participantes apresentavam acuidade visual normal e estavam livres de doenças oculares identificáveis. A FSCr foi medida com o método psicofísico da escolha forçada. Os resultados mostraram sensibilidade máxima na faixa de frequência radial de 0,25 cpg para os dois grupos. Os resultados mostraram ainda diferenças significantes entre as curvas de FSCr de crianças ouvintes e de crianças com surdez pré-lingual. Isto é, as crianças ouvintes precisaram de menos contraste do que as crianças surdas para detectar as frequências radiais. Esses resultados sugerem que, em níveis baixos de luminância, a FSCr das crianças ouvintes foi melhor do que a das crianças com surdez pré-lingual.

Métodos para fabricação de microeletrodos visando a detecção em microambientes

Analysis at microenvironments, like single cells or in minute volumes (nL), is an area of great interest for analytical and biological sciences. Measurements at these experimental conditions demand analytical tools (microelectrodes) capable of monitoring with rapid response, good resolution and minimal perturbation of the system. The major drawbacks in producing these microscopic electrodes have been largely overcome, principally due to the development of new fabrication methods. In this review, these procedures are described with emphasis to those devoted to the construction of microelectrodes for application in microenvironments. Examples of our efforts to use these devices as effective electrochemical sensors are also addressed.

Práticas preventivas de detecção de câncer em mulheres: comparação das estimativas dos inquéritos de saúde (ISA - Capital) e vigilância de fatores de risco e proteção para doenças crônicas por inquérito telefônico (VIGITEL - São Paulo)

OBJETIVO: O objetivo deste estudo foi comparar estimativas obtidas em inquéritos domiciliar e telefônico, da realização dos exames de Papanicolaou e mamografia em mulheres residentes no município de São Paulo em 2008, segundo características sociodemográficas, bem como dimensionar as diferenças observadas. MÉTODOS: Foram utilizados os dados do ISA - Capital 2008, inquérito domiciliar realizado no município de São Paulo pela Universidade de São Paulo (USP), Universidade Estadual de Campinas (UNICAMP) e Secretaria de Estado da Saúde com apoio da Secretaria Municipal de Saúde de São Paulo, e do VIGITEL - São Paulo, inquérito telefônico realizado pelo Ministério da Saúde para Vigilância de Fatores de Risco e Proteção para Doenças Crônicas. Estimativas da realização do exame de Papanicolaou e mamografia na vida, bem como a realização no último ano foram comparadas segundo o tipo de inquérito (domiciliar/telefone) por meio de regressão de Poisson ajustada por idade e escolaridade. RESULTADOS: Não foram encontradas diferenças estatisticamente significantes entre as estimativas obtidas pelo VIGITEL e ISA - Capital para as prevalências de realização de mamografia no último ano. No entanto, para as estimativas globais de realização do exame de Papanicolaou alguma vez na vida e no último ano e da mamografia na vida, foi possível verificar diferenças estatisticamente significantes, com prevalências de cobertura superiores entre as entrevistadas pelo inquérito telefônico. CONCLUSÃO: Os resultados sinalizam a tendência de superestimação de alguns indicadores de cobertura de mamografia e de exame de Papanicolaou nos dados de pesquisa via telefone, apontando a necessidade de novos estudos que também contribuam para o melhor entendimento das diferenças observadas com o uso de diferentes modalidades de inquéritos.

Comparação entre pontos de corte para excesso de peso na detecção de pressão arterial elevada em adolescentes

OBJETIVOS: Avaliar a acurácia de três pontos de corte na determinação da pressão arterial elevada em adolescentes, dada a forte relação entre o excesso de peso e valores elevados de pressão arterial. MÉTODOS: Participaram do estudo 1.021 adolescentes de ambos os sexos, selecionados de maneira aleatória nas escolas públicas e particulares de Londrina (PR). O peso corporal foi aferido por meio de balança digital, e a estatura, por um estadiômetro portátil com extensão máxima de 2 metros. A pressão arterial foi avaliada através de um aparelho automático. A capacidade do índice de massa corporal de detectar a pressão arterial elevada foi averiguada por meio da curva ROC e seus parâmetros (sensibilidade, especificidade e área sob a curva). RESULTADOS: Os pontos de corte da proposta nacional apresentaram maior acurácia (masculino: 0,636±0,038; feminino: 0,585±0,043) quando comparados aos pontos de corte das propostas internacional (masculino: 0,594±0,040; feminino: 0,570±0,044) e norte-americana (masculino: 0,612±0,039; feminino: 0,578±0,044). CONCLUSÃO: A proposta nacional foi a que apresentou melhor acurácia na indicação de valores elevados de pressão arterial.

Ultrastructure of the Interface between Periodontal Tissues and Titanium Mini-Implants

Objective: To describe the ultrastructure of the interface between periodontal tissues and titanium mini-implants in rat mandibles. Materials and Methods: A titanium mini-implant was placed between the buccal roots of the mandibular first molar of 24 adult rats. After 21, 30, 45, 60, 90, and 120 days of implantation, the mandibular portion was removed and fixed in cacodylate-buffered 2% glutaraldehyde + 2.5% formaldehyde. The material was decalcified and processed for scanning and transmission electron microscopy. Results: Ultrastructural analysis revealed a thin cementum-like layer at longer times after implantation at the areas in which the periodontal ligament was in contact with the implant. Conclusions: The alveolar bone and the periodontal ligament reorganized their constituents around the implant, and a thin cementum-like layer was formed at longer times after implantation at the areas in which the periodontal ligament was in contact with the implant. (Angle Orthod. 2010;80:459-435.)

Accurate prediction of the Si/SiO(2) interface band offset using the self-consistent ab initio DFT/LDA-1/2 method

We use the density functional theory/local-density approximation (DFT/LDA)-1/2 method [L. G. Ferreira , Phys. Rev. B 78, 125116 (2008)], which attempts to fix the electron self-energy deficiency of DFT/LDA by half-ionizing the whole Bloch band of the crystal, to calculate the band offsets of two Si/SiO(2) interface models. Our results are similar to those obtained with a ""state-of-the-art"" GW approach [R. Shaltaf , Phys. Rev. Lett. 100, 186401 (2008)], with the advantage of being as computationally inexpensive as the usual DFT/LDA. Our band gap and band offset predictions are in excellent agreement with experiments.

Atomistic molecular dynamics study of interface formation: Al on poly(p-phenylene vinylene)

We model interface formation by metal deposition on the conjugated polymer poly-para-phenylene vinylene, studying direct aluminum and layered aluminum-calcium structures Al/PPV and Al/Ca/PPV. To do that we use classical molecular dynamics simulations, checked by ab initio density-functional theory calculations, for selected relevant configurations. We find that Al not only migrates easily into the film, with a strong charge transfer to the neighboring chains, but also promotes rearrangement of the polymer in the interfacial region to the hexagonal structure. On the other hand, our results indicate that a thin Ca layer is sufficient to protect the film and maintain a well-defined metal/polymer interface, and that also a thin Al capping layer may protect the whole from environmental degradation.

Soliton dynamics at an interface between a uniform medium and a nonlinear optical lattice

We study trapping and propagation of a matter-wave soliton through the interface between uniform medium and a nonlinear optical lattice. Different regimes for transmission of a broad and a narrow solitons are investigated. Reflections and transmissions of solitons are predicted as a function of the lattice phase. The existence of a threshold in the amplitude of the nonlinear optical lattice, separating the transmission and reflection regimes, is verified. The localized nonlinear surface state, corresponding to the soliton trapped by the interface, is found. Variational approach predictions are confirmed by numerical simulations for the original Gross-Pitaevskii equation with nonlinear periodic potentials.

Substrate/semiconductor interface effects on the emission efficiency of luminescent polymers

The importance of interface effects for organic devices has long been recognized, but getting detailed knowledge of the extent of such effects remains a major challenge because of the difficulty in distinguishing from bulk effects. This paper addresses the interface effects on the emission efficiency of poly(p-phenylene vinylene) (PPV), by producing layer-by-layer (LBL) films of PPV alternated with dodecylbenzenesulfonate. Films with thickness varying from similar to 15 to 225 nm had the structural defects controlled empirically by converting the films at two temperatures, 110 and 230 degrees C, while the optical properties were characterized by using optical absorption, photoluminescence (PL), and photoluminescence excitation spectra. Blueshifts in the absorption and PL spectra for LBL films with less than 25 bilayers (<40-50 nm) pointed to a larger number of PPV segments with low conjugation degree, regardless of the conversion temperature. For these thin films, the mean free-path for diffusion of photoexcited carriers decreased, and energy transfer may have been hampered owing to the low mobility of the excited carriers. The emission efficiency was then found to depend on the concentration of structural defects, i.e., on the conversion temperature. For thick films with more than 25 bilayers, on the other hand, the PL signal did not depend on the PPV conversion temperature. We also checked that the interface effects were not caused by waveguiding properties of the excited light. Overall, the electronic states at the interface were more localized, and this applied to film thickness of up to 40-50 nm. Because this is a typical film thickness in devices, the implication from the findings here is that interface phenomena should be a primary concern for the design of any organic device. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622143]

Interface roughness in short-period InGaAs/InP superlattices

Electron mobility was studied in lattice-matched short-period InGaAs/InP superlattices as a function of the width of the wells. The decreasing mobility with decreasing well width was shown to occur due to the interface roughness. The roughnesses of InGaAs/InP and GaAs/AlGaAs interfaces were compared. Much smoother InGaAs/InP interfaces resulted in higher electron mobility limited by interface roughness.

Exploitation of a single interface flow system for on-line aqueous biphasic extraction

The exploitation of aqueous biphasic extraction is proposed for the first time in flow analysis This extraction strategy stands out for being environmentally attractive since it is based in the utilization of two immiscible phases that are intrinsically aqueous The organic solvents of the traditional liquid-liquid extractions ale no longer used, being replaced by non-toxic, non-flammable and non-volatile ones. A single interface flow analysis (SIFA) system was implemented to carry out the extraction process due to its favourable operational characteristics that include the high automation level and simplicity of operation, the establishment of a dynamic interface where the mass transfer occurred between the two immiscible aqueous phases, and the versatile control over the extraction process namely the extraction time The application selected to demonstrate the feasibility of SIFA to perform this aqueous biphasic extraction was the pre-concentration of lead. After extraction, lead reacted with 8-hydroxyquinoline-5-sulfonic acid and the resulting product was determined by a fluorimetric detector included in the flow manifold. Therefore, the SIFA single interface was used both as extraction (enrichment) and reaction interface. (C) 2010 Elsevier B.V All rights reserved.

Single interface flow analysis with accuracy assessment

Single interface flow systems (SIFA) present some noteworthy advantages when compared to other flow systems, such as a simpler configuration, a more straightforward operation and control and an undemanding optimisation routine. Moreover, the plain reaction zone establishment, which relies strictly on the mutual inter-dispersion of the adjoining solutions, could be exploited to set up multiple sequential reaction schemes providing supplementary information regarding the species under determination. In this context, strategies for accuracy assessment could be favourably implemented. To this end, the sample could be processed by two quasi-independent analytical methods and the final result would be calculated after considering the two different methods. Intrinsically more precise and accurate results would be then gathered. In order to demonstrate the feasibility of the approach, a SIFA system with spectrophotometric detection was designed for the determination of lansoprazole in pharmaceutical formulations. Two reaction interfaces with two distinct pi-acceptors, chloranilic acid (CIA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) were implemented. Linear working concentration ranges between 2.71 x 10(-4) to 8.12 x 10(-4) mol L(-1) and 2.17 x 10(-4) to 8.12 x 10(-4) mol L(-1) were obtained for DDQ and CIA methods, respectively. When compared with the results furnished by the reference procedure, the results showed relative deviations lower than 2.7%. Furthermore. the repeatability was good, with r.s.d. lower than 3.8% and 4.7% for DDQ and CIA methods, respectively. Determination rate was about 30 h(-1). (C) 2009 Elsevier B.V. All rights reserved.

Exploiting pi-acceptors for the determination of thyroid hormones (T3 and T4) using a single interface flow system

A fully automated methodology was developed for the determination of the thyroid hormones levothyroxine (T4) and liothyronine (T3). The proposed method exploits the formation of highly coloured charge-transfer (CT) complexes between these compounds, acting as electron donors, and pi-acceptors such as chloranilic acid (CIA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). For automation of the analytical procedure a simple, fast and versatile single interface flow system (SIFA)was implemented guaranteeing a simplified performance optimisation, low maintenance and a cost-effective operation. Moreover, the single reaction interface assured a convenient and straightforward approach for implementing job`s method of continuous variations used to establish the stoichiometry of the formed CT complexes. Linear calibration plots for levothyroxine and liothyronine concentrations ranging from 5.0 x 10(-5) to 2.5 x 10(-4) mol L(-1) and 1.0 x 10(-5) to 1.0 x 10(-4) mol L(-1), respectively, were obtained, with good precision (R.S.D. <4.6% and <3.9%) and with a determination frequency of 26 h(-1) for both drugs. The results obtained for pharmaceutical formulations were statistically comparable to the declared hormone amount with relative deviations lower than 2.1%. The accuracy was confirmed by carrying out recovery studies, which furnished recovery values ranging from 96.3% to 103.7% for levothyroxine and 100.1% for liothyronine. (C) 2009 Elsevier B.V. All rights reserved.