Bovine-serum-albumin-containing receptor phase better predicts transdermal absorption parameters for lipophilic compounds

Based on the hypothesis that limited receptor solubility of lipophilic compounds may result in lower observed permeability parameters, the aim of this study was to determine the in vitro human epidermal permeability coefficients and membrane retention of a series of aliphatic alcohols (C1-C10, log p -0.72 to 4.06) using two different receptor solutions (water and 4% bovine serum albumin in phosphate-buffered saline). Aqueous solutions of radiolabeled alcohols were dosed into the stratum corneum side of membranes mounted in side-by-side glass diffusion cells. Appearance of alcohol in the receptor compartment filled with either of the two solutions was monitored over a 7 h period when both stratum corneum (assessed by tape stripping) and the remaining epidermis levels of radioactivity were determined. In a separate study the degree of binding of alcohols to 4% bovine serum albumin was determined. The data showed increased receptor phase solubility in the bovine serum albumin solution and higher permeability coefficients for the more lipophilic alcohols in the series. No changes were seen in the partitioning of the alcohols from the vehicle into either the stratum corneum or tape-stripped epidermis with the two receptor phases; however, a decrease in the amount of the more lipophilic alcohols partitioning into the water receptor phase from the tape-stripped epidermis was observed. We conclude that bovine serum albumin receptor phase allows better estimation of real permeability parameters for lipophilic compounds due to its increased solubility capacity and we question whether permeability parameters for lipophilic solutes from older data sets based on aqueous receptor phases are completely reliable.

Ultrasonic absorption in polymer gel dosimeters

Ultrasonic absorption in polymer gel dosimeters was investigated. An ultrasonic interferometer was used to study the frequency (f) dependence of the absorption coefficient (alpha) in a polyacrylamide gel dosimeter (PAG) in the frequency range 5-20 MHz. The frequency dependence of ultrasonic absorption deviated from that of an ideal viscous fluid. The presence of relaxation mechanisms was evidenced by the frequency dependence of alpha/f(2) and the dispersion in ultrasonic velocity. It was concluded that absorption in polymer gel dosimeters is due to a number of relaxation processes which may include polymer-solvent interactions as well as relaxation due to motion of polymer side groups. The dependence of ultrasonic absorption on absorbed dose and formulation was also investigated in polymer gel dosimeters as a function of pH and chemical composition. Changes in dosimeter pH and chemical composition resulted in a variation in ultrasonic dose response curves. The observed dependence on pH was considered to be due to pH induced modifications in the radiation yield while changes in chemical composition resulted in differences in polymerisation kinetics. (C) 2003 Elsevier B.V. All rights reserved.

Anomalous water absorption in porous materials

The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuntz and Lavallee (2001) discuss the anomalous behaviour and propose a non-Darcian model as a more appropriate physical description. We present an alternative Darcian explanation and theory that retrieves the earlier advantages of the simple sorptivity test in providing parametric information about the material's hydraulic properties and allowing simple predictive formulae for the wetting profile to be generated.

Absorption of primary macronutrients and soybean growth at different compactation densities and moisture levels in a silt loam soil

ABSTRACT Soybean cultivation is increasing rapidly in the region of Alto Vale do Itajaí, State of Santa Catarina, where there is a predominance of silt soils. The objective of this work was to evaluate the content of primary macronutrients in shoots and shoot and root vegetative growth of soybean (Glicine max L. Merrill) grown in a silt-loam soil under different compactation densities and moisture levels. A randomized block design in a 4x4 factorial arrangement was used, with four compactation densities: 1.00; 1.20; 1.40 and 1.60 Mg m-3, and four soil moisture levels: 0.130; 0.160; 0.190 and 0.220 kg kg-1 and four replications. Each pot consisted of the overlapping of three 150-mm PVC rings, where soil was maintained in the higher and lower part of the pot with a density of 1.00 Mg m-3 and in the intermediate ring, the compactation densities were increased. Values of soil density higher than 120 Mg m-3 negatively affected N, P and K uptake by soybean plants, as well as the plant mass of the shoots and roots. The higher levels of soil moisture reduced the compaction effect and promoted better absorption of P and K.

Innovative technological capability in firms of the tourism sector: a study of the hotels in the city of Rio de Janeiro during the 1990-2008 period

This article presents the preliminary report of the research project entitled "Innovative technological capability in firms of the tourism sector: a study of the hotels in the city of Rio de Janeiro during the 1990-2008 period". The objective of this project is to apply and evaluate an analytical model of technological capability and underlying learning processes and examine the accumulation trajectory of innovative technological capability in the firms of tourism service industry, and the impact of learning processes undertaken by these firms on the technological capability levels achieved during the 1990-2008 period.

Síntese e fotosensibilização de nanotubos de titanatos

Nesta tese é descrita a preparação de nanotubos de titanatos (TNT) via síntese hidrotérmica alcalina, usando uma nova metodologia que evita a utilização de TiO2 cristalino como precursor. Foi estudada a influência da substituição sódio/protão na estrutura, morfologia e propriedades ópticas dos materiais preparados. Os resultados mostraram que a substituição Na+ → H+ resulta numa redução na distância intercamadas dos TNTs, tendo sido medidos valores entre 1.13±0.03 nm e 0.70±0.02 nm para aquele parâmetro. O comportamento óptico dos TNTs foi estudado na região UV-vis, estimando-se um hiato óptico de energia 3.27±0.03 eV para a amostra com maior teor de sódio enquanto que para a amostra protonada foi determinado um valor de 2.81±0.02 eV. Estes valores mostram que a troca iónica Na+ → H+ teve influência no desvio da banda de absorção dos TNTs para a região do visível próximo. A actividade fotocatalítica dos TNTs na degradação do corante rodamina 6G (R6G) foi posteriormente estudada. Verificou-se que, apesar de a amostra com maior teor de sódio ter sido a que exibiu maior capacidade para adsorver o R6G, foi a amostra protonada que apresentou a actividade catalítica mais elevada na fotodegradação deste corante. Numa segunda fase, e com o objectivo de preparar novos materiais nanoestruturados fotosensíveis, procedeu-se à decoração dos TNTs protonados com semicondutores (SC) nanocristalinos usando um método novo. Para o efeito os TNTs foram decorados com nanocristalites de ZnS, CdS e Bi2S3. Foi estudada a influência do tipo de semicondutor na estrutura, morfologia e propriedades ópticas dos SC/TNTs obtidos. Verificou-se que, para qualquer dos semicondutores usados no processo de decoração, a estrutura dos TNTs é preservada e não ocorre segregação do SC. Verificou-se ainda que a morfologia dos nanocompósitos preparados depende fortemente da natureza do semicondutor. No que respeita ao comportamento óptico destes materiais, foram determinados hiatos ópticos de energia 3.67±0.03 eV, 2.47±0.03 eV e 1.35±0.01 eV para as amostras ZnS/TNT, CdS/TNT e Bi2S3/TNT, respectivamente. Estes resultados mostram que através do processo de decoração de TNTs com semicondutores podem ser preparados materiais nanocompósitos inovadores, com propriedades ópticas novas e/ou pré-definidas numa gama alargada do espectro electromagnético.

A simulation study on the abatement of CO2 emissions by de-absorption with monoethanolamine

Because of the adverse effect of CO2 from fossil fuel combustion on the earth's ecosystems, the most cost-effective method for CO2 capture is an important area of research. The predominant process for CO2 capture currently employed by industry is chemical absorption in amine solutions. A dynamic model for the de-absorption process was developed with monoethanolamine (MEA) solution. Henry's law was used for modelling the vapour phase equilibrium of the CO2, and fugacity ratios calculated by the Peng-Robinson equation of state (EOS) were used for H2O, MEA, N-2 and O-2. Chemical reactions between CO2 and MEA were included in the model along with the enhancement factor for chemical absorption. Liquid and vapour energy balances were developed to calculate the liquid and vapour temperature, respectively.

Colour filtering in a-SiC : H based p-i-n-p-i-n cells: A trade-off between bias polarity and absorption regions

A large area colour imager optically addressed is presented. The colour imager consists of a thin wide band gap p-i-n a-SiC:H filtering element deposited on the top of a thick large area a-SiC:H(-p)/a-Si:H(-i)/a-SiC:H(-n) image sensor, which reveals itself an intrinsic colour filter. In order to tune the external applied voltage for full colour discrimination the photocurrent generated by a modulated red light is measured under different optical and electrical bias. Results reveal that the integrated device behaves itself as an imager and a filter giving information not only on the position where the optical image is absorbed but also on it wavelength and intensity. The amplitude and sign of the image signals are electrically tuneable. In a wide range of incident fluxes and under reverse bias, the red and blue image signals are opposite in sign and the green signal is suppressed allowing blue and red colour recognition. The green information is obtained under forward bias, where the blue signal goes down to zero and the red and green remain constant. Combining the information obtained at this two applied voltages a RGB colour image picture can be acquired without the need of the usual colour filters or pixel architecture. A numerical simulation supports the colour filter analysis.

Effect of oxidative stress upon absorption of glucose by the human placenta: in vitro studies with BeWo cells

Pregnancy is a dynamic state and the placenta is a temporary organ that, among other important functions, plays a crucial role in the transport of nutrients and metabolites between the mother and the fetus, which is essential for a successful pregnancy. Among these nutrients, glucose is considered a primary source of energy and, therefore, fundamental to insure proper fetus development. Several studies have shown that glucose uptake is dependent on several morphological and biochemical placental conditions. Oxidative stress results from the unbalance between reactive oxygen species (ROS) and antioxidants, in favor of the first. During pregnancy, ROS, and therefore oxidative stress, increase, due to increased tissue oxygenation. Moreover, the relation between ROS and some pathological conditions during pregnancy has been well established. For these reasons, it becomes essential to understand if oxidative stress can compromise the uptake of glucose by the placenta. To make this study possible, a trophoblastic cell line, the BeWo cell line, was used. Experiments regarding glucose uptake, either under normal or oxidative stress conditions, were conducted using tert-butylhydroperoxide (tBOOH) as an oxidative stress inducer, and 3H-2-deoxy-D-glucose (3H-DG) as a glucose analogue. Afterwards, studies regarding the involvement of glucose facilitative transporters (GLUT) and the phosphatidylinositol 3-kinases (PI3K) and protein kinase C (PKC) pathways were conducted, also under normal and oxidative stress conditions. A few antioxidants, endogenous and from diet, were also tested in order to study their possible reversible effect of the oxidative effect of tBOOH upon apical 3H-DG uptake. Finally, transepithelial studies gave interesting insights regarding the apical-to-basolateral transport of 3H-DG. Results showed that 3H-DG uptake, in BeWo cells, is roughly 50% GLUT-mediated and that tBOOH (100 μM; 24h) decreases apical 3H-DG uptake in BeWo cells by about 33%, by reducing both GLUT- (by 28%) and non-GLUT-mediated (by 40%) 3H-DG uptake. Uptake of 3H-DG and the effect of tBOOH upon 3H-DG uptake are not dependent on PKC and PI3K. Moreover, the effect of tBOOH is not associated with a reduction in GLUT1 mRNA levels. Resveratrol, quercetin and epigallocatechin-3-gallate, at 50 μM, reversed, by at least 45%, the effect of tBOOH upon 3H-DG uptake. Transwell studies show that the apical-to-basolateral transepithelial transport of 3H-DG is increased by tBOOH.In conclusion, our results show that tBOOH caused a marked decrease in both GLUT and non-GLUT-mediated apical uptake of 3H-DG by BeWo cells. Given the association of increased oxidative stress levels with several important pregnancy pathologies, and the important role of glucose for fetal development, the results of this study appear very interesting.

Avaliação ecotoxicológica de lixiviados de lamas provenientes de estações de tratamento de águas. Capacidade de germinação de sementes de alface (lactuca sativa)

A água superficial para posterior consumo humano, tem de passar por diversas etapas de tratamento, de forma a dar cumprimento aos requisitos da legislação vigente, decreto-Lei n.º 306/2007 de 27 de Agosto. Como resultado do referido tratamento produzem-se resíduos, nomeadamente, as lamas de clarificação de água. De acordo com a estratégia da União Europeia, a deposição em aterro destas lamas apenas deverá ser efectuada em situações excepcionais ou temporárias. A procura de uma solução ambientalmente mais aceitável para o destino final a atribuir a estas lamas de clarificação de água deverá ser, um dos objectivos das empresas abastecedoras de água para consumo humano. Com o intuito de verificar a possibilidade de utilização das lamas produzidas nas Estações de Tratamento de Água (ETA) em solos agrícolas, realizaram-se testes ecotoxicológicos para avaliar a capacidade de germinação de sementes de alface (Lactuca sativa). Foram igualmente realizadas determinações de alguns metais nos lixiviados, por espectrofotometria de absorção atómica com atomização por chama e por Câmara de grafite. O cádmio e o chumbo por imposição da legislação aplicável aos géneros alimentícios, Regulamento (CE) 1881/2006 de 19 de Dezembro e o alumínio e o ferro por estarem presentes nos tratamentos de algumas das águas superficiais em estudo. As lamas estudadas eram provenientes de ETA com captação de água superficial em rios e albufeiras distintos do norte de Portugal, com utilização de tratamentos também diferentes. Os resultados obtidos com os lixiviados das lamas provenientes das ETA com captações dos rios Ferreira, Ferro e Vizela e Tâmega, evidenciaram inibição da germinação para algumas das diluições testadas. No entanto, não se observou qualquer efeito tóxico para as lamas das ETA com captações da albufeira do Alto Rabagão e dos rios Rabaçal, Douro e Paiva. Dos metais alumínio, cádmio, ferro e chumbo determinados nos lixiviados, apenas o alumínio estava acima do limite de detecção. No entanto, não foi possível estabelecer qualquer correlação entre o tratamento aplicado à água superficial nas várias ETA com a concentração do alumínio nem com os resultados dos ensaios ecotoxicológicos. Não obstante, parece haver relação entre a proximidade geográfica do local de captação de água e os resultados dos bioensaios.

Comparative study of amine solutions used in CO2 absorption/desorption cycles

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A New Method to Determine the Density and Water Absorption of Fine Recycled Aggregates

The construction industry keeps on demanding huge quantities of natural resources, mainly minerals for mortars and concrete production. The depletion of many quarries and environmental concerns about reducing the dumping of construction and demolition waste in quarries have led to an increase in the procuring and use of recycled aggregates from this type of waste. If they are to be incorporated in concrete and mortars it is essential to know their properties to guarantee the adequate performance of the end products, in both mechanical and durability-related terms. Existing regulated tests were developed for natural aggregates, however, and several problems arise when they are applied to recycled aggregates, especially fine recycled aggregates (FRA). This paper describes the main problems encountered with these tests and proposes an alternative method to determine the density and water absorption of FRA that removes them. The use of sodium hexametaphosphate solutions in the water absorption test has proven to improve its efficiency, minimizing cohesion between particles and helping to release entrained air.

Cobalt complexes with pyrazole ligands as catalyst precursors for the peroxidative oxidation of cyclohexane: Z-ray absorption spectroscopy studies and biological applications

[CoCl(-Cl)(Hpz(Ph))(3)](2) (1) and [CoCl2(Hpz(Ph))(4)] (2) were obtained by reaction of CoCl2 with HC(pz(Ph))(3) and Hpz(Ph), respectively (Hpz(Ph)=3-phenylpyrazole). The compounds were isolated as air-stable solids and fully characterized by IR and far-IR spectroscopy, MS(ESI+/-), elemental analysis, cyclic voltammetry (CV), controlled potential electrolysis, and single-crystal X-ray diffraction. Electrochemical studies showed that 1 and 2 undergo single-electron irreversible (CoCoIII)-Co-II oxidations and (CoCoI)-Co-II reductions at potentials measured by CV, which also allowed, in the case of dinuclear complex 1, the detection of electronic communication between the Co centers through the chloride bridging ligands. The electrochemical behavior of models of 1 and 2 were also investigated by density functional theory (DFT) methods, which indicated that the vertical oxidation of 1 and 2 (that before structural relaxation) affects mostly the chloride and pyrazolyl ligands, whereas adiabatic oxidation (that after the geometry relaxation) and reduction are mostly metal centered. Compounds 1 and 2 and, for comparative purposes, other related scorpionate and pyrazole cobalt complexes, exhibit catalytic activity for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions (room temperature, aqueous H2O2). Insitu X-ray absorption spectroscopy studies indicated that the species derived from complexes 1 and 2 during the oxidation of cyclohexane (i.e., Ox-1 and Ox-2, respectively) are analogous and contain a Co-III site. Complex 2 showed low invitro cytotoxicity toward the HCT116 colorectal carcinoma and MCF7 breast adenocarcinoma cell lines.

Influence of the Sodium/Proton replacement on the structural, morphological and photocatalytic properties of titanate nanotubes

Titanate nanotubes (TNT) with different sodium contents have been synthesised using a hydrothermal approach and a swift and highly controllable post-washing processes. The influence of the sodium/proton replacement on the structural and morphological characteristics of the prepared materials was analysed. Different optical behaviour was observed depending on the Na+/H+ samples’ content. A band gap energy of 3.27±0.03 eV was estimated for the material with higher sodium content while a value of 2.81±0.02 eV was inferred for the most protonated material, which therefore exhibits an absorption edge in the near visible region. The point of zero charge of the materials was determined and the influence of the sodium content on the adsorption of both cationic and anionic organic dyes was studied. The photocatalytic performance of the TNT samples was evaluated in the rhodamine 6G degradation process. Best photodegradation results were obtained when using the most protonated material as catalyst, although this material has shown the lowest R6G adsorption capability.

Métodos "verdes" de produção de nanomateriais que promovem nanotecnologias sustentáveis

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