Nanoplasmonic response of porous Au-TiO2 thin films prepared by oblique angle deposition.

In this work, a versatile method is proposed to increase the sensitivity of optical sensors based on the localized surface plasmon resonance (LSPR) phenomenon. It combines a physical deposition method with the oblique angle deposition technique, allowing the preparation of plasmonic thin films with tailored porosity. Thin films of Au-TiO2 were deposited by reactive magnetron sputtering in a 3D nanostructure (zigzag growth), at different incidence angles (0° ≤ α ≤ 80°), followed by in-air thermal annealing at 400 °C to induce the growth of the Au nanoparticles. The roughness and surface porosity suffered a gradual increment by increasing the incidence angle. The resulting porous zigzag nanostructures that were obtained also decreased the principal refractive indexes (RIs) of the matrix and favoured the diffusion of Au through grain boundaries, originating broader nanoparticle size distributions. The transmittance minimum of the LSPR band appeared at around 600 nm, leading to a red-shift to about 626 nm for the highest incidence angle α = 80°, due to the presence of larger (scattering) nanoparticles. It is demonstrated that zigzag nanostructures can enhance adsorption sites for LSPR sensing by tailoring the porosity of the thin films. Atmosphere controlled transmittance-LSPR measurements showed that the RI sensitivity of the films is improved for higher incidence angles.

Nano-sculptured Janus-like TiAg thin films obliquely deposited by GLAD co-sputtering for temperature sensing.

Inclined, zigzag and spiral TiAg films were prepared by glancing angle co-deposition, using two distinct Ti and Ag targets with a particle incident angle of 80° and Ag contents ranging from 20 to 75 at%. The effect of increasing Ag incorporation and columnar architecture change on the morphological, structural and electrical properties of the films was investigated. It is shown that inclined columnar features (ß = 47°) with high porosity were obtained for 20 at% Ag, with the column angle sharply decreasing (ß = 21°) for 50 at% Ag, and steeply increasing afterwards until ß = 37° for the film with 75 at% Ag. The sputtered films exhibit a rather well-crystallized structure for Ag contents ≥50 at%, with a TiAg (111) preferential growth. No significant oxidation was detected in all films, except for the one with 20 at% Ag, after two 298-473-298 K temperature cycles in air. The calculated temperature coefficient of resistivity (TCR) values vary between 1.4 and 5.5 × 10-4 K-1. Nano-sculptured spiral films exhibit consistently higher resistivity (ρ = 1.5 × 10-6 Ω m) and TCR values (2.9 × 10-4 K-1) than the inclined one with the same Ag content (ρ = 1.2 × 10-6 Ω m and TCR = 2.0 × 10-4 K-1). No significant changes are observed in the zigzag films concerning these properties. The effective anisotropy A eff at 473 K changes from 1.3 to 1.7 for the inclined films. Spiral films exhibit an almost completely isotropic behavior with A eff = 1.1. Ag-rich TiAg core + shell Janus-like columns were obtained with increasing Ag concentrations.

Contact Pressure and Flexibility of Multipin Dry EEG Electrodes.

In state-of-the-art electroencephalography (EEG) Silver/Silver-Chloride electrodes are applied together with electrolyte gels or pastes. Their application requires extensive preparation, trained medical staff and limits measurement time and mobility. We recently proposed a novel multichannel cap system for dry EEG electrodes for mobile and out-of-the-lab EEG acquisition. During the tests with these novel polymer-based multipin dry electrodes, we observed that the quality of the recording depends on the applied normal force and resulting contact pressure. Consequently, in this paper we systematically investigate the influence of electrode-skin contact pressure and electrode substrate flexibility on interfacial impedance and perceived wearing comfort in a study on 12 volunteers. The normal force applied to the electrode was varied between the minimum required force to achieve impedances and a maximum of 4 N, using a new force measurement applicator. We found that for a polymer shore hardness A98, with increasing normal force, the impedance decreases from and to and at frontal hairless and temporal hairy positions, respectively. Similar results were obtained for shore A90, A80, and A70. The best compromise of low and stable impedances as well as a good wearing comfort was determined for applied normal forces between 2 and 3 N using electrodes with shore A98 or A90. Our results provide the basis for improved EEG cap designs with optimal wearing comfort and recording quality for dry multipin electrodes, which will enable new fields of application for EEG.

In-service characterization of a polymer wick-based quasi-dry electrode for rapid pasteless electroencephalography.

A novel quasi-dry electrode prototype, based on a polymer wick structure filled with a specially designed hydrating solution is proposed for electroencephalography (EEG) applications. The new electrode does not require the use of a conventional electrolyte paste to achieve a wet, low-impedance scalp contact. When compared to standard commercial Ag/AgCl sensors, the proposed wick electrodes exhibit similar electrochemical noise and potential drift values. Lower impedances are observed when tested in human volunteers due to more effective electrode/skin contact. Furthermore, the electrodes exhibit an excellent autonomy, displaying an average interfacial impedance of 37±11 kΩ cm2 for 7 h of skin contact. After performing bipolar EEG trials in human volunteers, no substantial differences are evident in terms of shape, amplitude and spectral characteristics between signals of wick and commercial wet electrodes. Thus, the wick electrodes can be considered suitable to be used for rapid EEG applications (electrodes can be prepared without the presence of the patient) without the traditional electrolyte paste. The main advantages of these novel electrodes over the Ag/AgCl system are their low and stable impedance (obtained without conventional paste), long autonomy, comfort, lack of dirtying or damaging of the hair and because only a minimal cleaning procedure is required after the exam.

Impact of Land Use on the Mobility of Hg Species in Different Compartments of a Tropical Watershed in Brazil.

This study evaluated the levels of total Hg and CH3Hg+ from a comprehensive perspective, considering the retention, leaching, and deposition of these contaminants in the main compartments (soil, plant litter, and sediment) of three landscapes (Atlantic Forest, pasture, and agricultural area) in a watershed in northern Rio de Janeiro State, Brazil. Variables analyzed were total Hg, CH3Hg+, organic carbon, total nitrogen, grain size, and surface area. In soil samples, total Hg levels were the highest in agricultural soil followed by forest soil and pasture (97.3, 87.6, and 77.1 ng g-1, respectively), and CH3Hg+ was lower than 1.7%. Total Hg levels in leaf litter varied between 22.6 and 34.2 ng g-1, and CH3Hg+ was 4.37%. In sediment, Hg (60-180 ng g-1) and CH3Hg+ (<1%) indicate the transport of these contaminants from soils to this compartment and may be associated with soil use and cover. Multiple regressions were used to understand the dispersion of Hg species, and the effect of each variable varied with the landscape, showing that plant cover should not be ignored in investigations related to Hg species retention in a watershed. The landscapes surveyed in the present study clearly influence the quantitative and qualitative distribution of Hg species. On the other hand, anthropic processes associated with changes in soil use did not have any critical effects on the absolute levels of total Hg and CH3Hg+, meaning that the landscapes evaluated seem to represent the background concentration of these chemical species for the evaluated watershed.

In situ electrical resistivity measurements of vanadium thin films performed in vacuum during different annealing cycles.

The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO2. After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture.

Assessing a novel polymer-wick based electrode for EEG neurophysiological research.

BACKGROUND: The EEG technique has decades of valid applications in clinical and experimental neurophysiology. EEG equipment and data analysis methods have been characterized by remarkable developments, but the skin-to-electrode signal transfer remains a challenge for EEG recording. NEW METHOD: A novel quasi-dry system - the polymer wick-based electrode - was developed to overcome the limitations of conventional dry and wet silver/silver-chloride (Ag/AgCl) electrodes for EEG recording. RESULTS: Nine participants completed an auditory oddball protocol with simultaneous EEG acquisition using both the conventional Ag/AgCl and the wick electrodes. Wick system successfully recorded the expected P300 modulation. COMPARISON WITH EXISTING METHOD(S): Standard ERP analysis, residual random noise analysis, and single-trial analysis of the P300 wave were performed in order to compare signal acquired by both electrodes. It was found that the novel wick electrode performed similarly to the conventional Ag/AgCl electrodes. CONCLUSIONS: The developed wick electrode appears to be a reliable alternative for EEG research, representing a promising halfway alternative between wet and dry electrodes.

Optical resilience of the Paraíba do Sul River (Brazil) during a toxic spill of a wood-pulping factory: the Cataguazes accident.

This study investigates the inherent optical properties (IOP) of a Brazilian river during a non-natural, anthropogenically mediated, toxic spill of a wood-pulping factory (the 'Cataguazes accident'). The results indicated an outstanding transformation in the river water chromophoric dissolved organic matter (CDOM) pools. For instance, increases in CDOM absorption coefficients, a(CDOM)(lambda), which were averaged at specific spectral intervals, [see text], ranged from 58-fold at the UV-B and UV-A ranges to 95-fold at the PAR range. As a result, the water color expressed as CDOM absorption at 440 nm, a(CDOM (440), varied from 4.16 to 365.03 m(-1). For S-coefficient, the variations ranged from approximately 1.1 to 5.6-fold, respectively, at the 300-650 nm and UV-B range. The variability of S as a proxy of dissolved chromophores was thus clearly influenced by the spectral range used. Optical proportions were also investigated through the use of [see text] and S ratios at the UV-B, UV-A, and PAR ranges and, in the case of [see text], also at the NIR range. This approach also showed clear variations between the water samples, likely reflecting changes in the composition of optically active substances in the river system. As a whole, the findings obtained here indicated that both the quantity and quality of the chromophoric material dissolved in the river water were greatly altered by the toxic spill. The changes in the optical properties of the river water, although extreme and likely with no parallel in the literature, were quite rapid as indicated by the optical resilience of the system. Overall, this study indicates that IOP might be thought, and possibly used, as a metric tool for monitoring the state of waters and aquatic ecosystems.

Funçäo da córtex adrenal em pacientes com paracoccidioidomicose: estudo através da dosagem radioimunológica do ACTH plasmático / Function of the adrenal cortex in patients with paracoccidioidomycosis: study by radioimmune assay of plasma ACTH

Foram estudados 15 pacientes com paracoccidioidomicose (PMC), dos quais 14 com a forma disseminada e um com a forma pulmonar progressiva, sendo 10 virgens de tratamento e cinco com recidiva da micose. O diagnóstico micológico foi feito através da evidenciaçäo etiológica em espécimes obtidos das lesöes: exame direto (KOH), histopatológico e/ou cultura. A funçäo adrenocortical foi estudada através das dosagens hormonais basais (cortisol plasmático-ritmo circadiano, ACTH plasmático e 17 OHCS na urina de 24 horas) e pós-teste de estímulo pelo ACTH exógeno (Cortrosina), empregando-se kits comerciais para essas dosagens. O trabalho visou a detecçäo da elevaçäo dos níveis plasmáticos de ACTH, a descoberta de pequenas reservas adrenocorticais e a evidenciaçäo de graus menores de falência adrenal (insuficiência corticoadrenal primária) por meio da dosagem do ACTH plasmático (método radioimunoensaio) em paracoccidioidomicóticos. Os resultados demonstram a presença de três grupos de pacientes: 1) ACTH plasmático < 20pg/ml; 2) ACTH plasmático entre 20 e 50pg/ml; e 3) ACTH plasmático > 58pg/ml. Feita a correlaçäo ACTH-cortisol pós-teste de estímulo pelo ACTH exógeno, oito pacientes situaram-se no grupo 1, sendo que dois deles apresentaram queda menor que duas vezes o basal, enquanto que nos quatro pacientes do grupo 3 ficou bem evidenciada a elevaçäo do ACTH plasmático em níveis superiores ao normal, dos quais dois mostraram resposta nula pós-estímulo, junto a sintomas e sinais de doença de Addison, satisfazendo critérios de insuficiência supra-renal primária. Na correlaçäo ACTH-17 OHCS pós-teste de estímulo pelo ACTH, oito pacientes situaram-se no grupo 1, sendo que sete apresentaram níveis de 17 OHCS menores que duas vezes o basal. Em três dos quatro pacientes do grupo 3, ficou comprovada insuficiência supra-renal primária, ao passo que o quarto paciente do grupo mostrou resposta aos 17 OHCS superior a três vezes o basal