Corrosion behavior of carbon steel protected with single and bi-layer of silane films filled with silica nanoparticles

The electrochemical behaviour of carbon steel coated with bis-[trimethoxysilylpropyl]amine (BTSPA) filled with silica nanoparticles in naturally aerated 0.1 mol L-1 NaCl solutions was evaluated. The coating was prepared by adding different concentrations of silica nanoparticles (100, 200, 300, 400 and 500 ppm) to the hydrolysis solution and then a second layer without silica nanoparticles was applied. The electrochemical behavior of the coated steel was evaluated by means of open-circuit potential (E-OC), electrochemical impedance spectroscopy (EIS) and polarization curves. Surface characterization was made by atomic force microscopy (AFM), and its hydrophobicity assessed by contact angle measurements. EIS diagrams have shown an improvement of the barrier properties of the silane layer with the silica addition, which was further improved on the bi-layer system. However, a dependence on the filler concentration was verified, and the best electrochemical response was obtained for samples modified with 300 ppm of silica nanoparticles. AFM images have shown a homogeneous distribution of the silica nanoparticles on the sample surface; however particles agglomeration was detected, which degraded the corrosion protection performance. The results were explained on the basis of the improvement of the barrier properties of the coating due to the filler addition and on the onset of defective regions on the more heavily filled coatings allowing easier electrolyte penetration. (C) 2007 Elsevier B.V. All rights reserved.

a-SiC : H anti-resonant layer ARROW waveguides

Over the last decades, anti-resonant reflecting optical waveguides (ARROW) have been used in different integrated optics applications. In this type of waveguide, light confinement is partially achieved through an anti-resonant reflection. In this work, the simulation, fabrication and characterization of ARROW waveguides using dielectric films deposited by a plasma-enhanced chemical vapor deposition (PECVD) technique, at low temperatures(similar to 300 degrees C), are presented. Silicon oxynitride (SiO(x)N(y)) films were used as core and second cladding layers and amorphous hydrogenated silicon carbide(a-SiC:H) films as first cladding layer. Furthermore, numerical simulations were performed using homemade routines based on two computational methods: the transfer matrix method (TMM) for the determination of the optimum thickness of the Fabry-Perot layers; and the non-uniform finite difference method (NU-FDM) for 2D design and determination of the maximum width that yields single-mode operation. The utilization of a silicon carbide anti-resonant layer resulted in low optical attenuations, which is due to the high refractive index difference between the core and this layer. Finally, for comparison purposes, optical waveguides using titanium oxide (TiO(2)) as the first ARROW layer were also fabricated and characterized.

Improved effective charge density in MOS capacitors with PECVD SiOxNy dielectric layer obtained at low RF power

In this work SiOxNy films are produced and characterized. Series of samples were deposited by the plasma enhanced chemical vapor deposition (PECVD) technique at low temperatures from silane (SiH4), nitrous oxide (N2O) and helium (He) precursor gaseous mixtures, at different deposition power in order to analyze the effect of this parameter on the films structural properties, on the SiOxNy/Si interface quality and on the SiOxNy effective charge density. In order to compare the film structural properties with the interface (SiOxNy/Si) quality and effective charge density, MOS capacitors were fabricated using these films as dielectric layer. X-ray absorption near-edge spectroscopy (XANES), at the Si-K edge, was utilized to investigate the structure of the films and the material bonding characteristics were analyzed through Fourier transform infrared spectroscopy (FTIR). The MOS capacitors were characterized by low and high frequency capacitance (C-V) measurements, in order to obtain the interface state density (D-it) and the effective charge density (N-ss). An effective charge density linear reduction for decreasing deposition power was observed, result that is attributed to the smaller amount of ions present in the plasma for low RF power. (C) 2008 Elsevier B.V. All rights reserved.

Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene

We demonstrate anisotropic etching of single-layer graphene by thermally activated nickel nanoparticles. Using this technique, we obtain sub-10-nm nanoribbons and other graphene nanostructures with edges aligned along a single crystallographic direction. We observe a new catalytic channeling behavior, whereby etched cuts do not intersect, resulting in continuously connected geometries. Raman spectroscopy and electronic measurements show that the quality of the graphene is resilient under the etching conditions, indicating that this method may serve as a powerful technique to produce graphene nanocircuits with well-defined crystallographic edges.

Body weight as an indicator of fat-free mass in active elderly women

Objective: Fat-free mass (FFM) reduction and the tendency for a reduction in surrounding fatty issue and increase in the middle are a natural consequence of growing old and should be studied in order to gain a better understanding of the aging process. This study set out to find the FFM differences between active elderly women in two age groups (60-69 and 70-80 years) and to determine which of the anthropometric measurements, body weight (BW), abdominal circumference (AC), or body mass index (BMI) are the best predictors of FFM variation within the group. Methods: Eighty-one (n = 81) active elderly women of the Third Age willingly signed up to participate in the research during the activities at the University of the Third Age (UTA) in Brazil. The research was approved by the Research Ethics Committee of the Faculty of Medical Sciences of the State University of Campinas (UNICAMP). Body weight (BW), height (H) and the BMI were measured according to the international standards. The AC was measured in centimetres at the H of the navel and body composition was ascertained using bioimpedance analysis. The SAS program was used to perform the statistical analysis of independent samples and parametric data. Results: The results showed FFM values with significant differences between the two groups, with the lowest values occurring among the women who were over 70 years of age. In the analysis, the Pearson`s Correlation Coefficient for each measured independent variable was ascertained, with the BW measurement showing the highest ratio (0.900). Conclusions: The BW measurement was regarded as reliable, low-cost and easy to use for monitoring FFM in elderly women who engage in physical activities. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Growth-active gibberellins overcome the very slow shoot growth of Hancornia speciosa, an important fruit tree from the Brazilian ""Cerrado""

Shoot elongation of Hancornia speciosa, an endangered tree from the Brazilian savannah ""Cerrado"", is very slow, thus limiting nursery production of plants. Gibberellins (GAs) A(1), A(3), and A(5), and two inhibitors of GA biosynthesis, trinexapac-ethyl and ancymidol were applied to shoots of Hancornia seedlings. GA(1) and GA(3) significantly stimulated shoot elongation, while GA(5) had no significant effect. Trinexapac-ethyl and ancymidol, both at 100 A mu g per seedling, inhibited shoot elongation up to 45 days after treatment, though the effect was statistically significant only for ancymidol. Somewhat surprisingly, exogenous GA(3) more effectively stimulated shoot elongation in SD-grown plants, than in LD-grown plants. The results from exogenous application of GAs and inhibitors of GA biosynthesis imply that Hancornia shoot growth is controlled by GAs, and that level of endogenous growth-active GAs is likely to be the limiting factor for shoot elongation in Hancornia. Application of GAs thus offer a practical method for nursery production of Hancornia seedlings for outplanting into the field.

Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean

Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean Asian rust, caused by the fungus Phakopsora pachyrhizi, is one of the most serious phytosanitary problems of soybean in Brazil, especially because no cultivars with satisfactory resistance levels as yet exist. The objective of this study was to evaluate the influence of luminosity and of leaf epicuticular wax on the infection of soybean by P. pachyrhizi. The adaxial and abaxial leaflet surfaces of the first trifoliate leaf from cultivar BRS 154, phenological stage V2, were inoculated with a suspension of 105 uredospores/mL. The plants were kept for 24 hours in a humid chamber at temperature of 23 degrees C, in light or dark conditions, using a factorial design. Subsequently, the plants were maintained for 14 days under a 12-hour photoperiod. The disease severity and density were evaluated. For in vitro experiments, in light or dark conditions, the evaluation was done in terms of uredospore germination and appressorium formation. The wax content of adaxial and abaxial leaflets was analyzed quantitatively using chloroform extraction and ultrastructurally using scanning electron microscope. Higher density and severity were observed when the adaxial surface was inoculated, with later incubation of the plants in the dark, with no significant interaction between these factors. Spore germination in the dark (40.7%) was statistically different from spore germination in the light (28.5%). The same effect was observed with appressorium formation, in the dark (24.7%) and in the light (12.8%). The quantity and the ultrastructural aspects of epicuticular wax content did not show differences between the adaxial and abaxial surfaces; nor did they show any effect on infection by Phakopsora pachyrhizi in the soybean cultivar studied.

Synergism between lipoxygenase-active soybean flour and ascorbic acid on rheological and sensory properties of wheat bread

BACKGROUND: The interaction between lipoxygenase-active soybean flour (LOX) and ascorbic acid (AA), on colour, rheological and sensory properties of wheat bread was studied with the aim of reducing the applied quantity of additives in bread formulations. RESULTS: The ascorbic acid (0-500 ppm) and active soybean flour (0-1%) mixture improved bread-crumb colour by lowering the yellow hue in a higher proportion than those expressed by the components alone, characterising a synergistic mechanism ((y) over cap (b) = 15.1- (1.7 x LOX) - (0.5 x AA) - (5.8 x LOX x AA), where : (y) over cap (b) represent the estimated value for the yellow hue parameter). No differences in flavour and porosity were seen between the samples. As supported by the instrumental methods, breads made with active soybean flour and ascorbic acid (LOX + AA) had whiter crumbs and were softer and springier than controls as assessed by a trained sensory panel. In summary, the combination of both active soybean flour and ascorbic acid showed synergism, promoting a greater bleaching effect than when used alone. CONCLUSION: These results suggest the potential use of active soybean flour as a synergistic ingredient in the substitution of artificial additives in bread making. Since the interaction on the bleaching response was not linear and active soybean flour showed a higher iron concentration (66.40 +/- 4.23 mu g g(-1)) than non-active soybean flour (52.30 +/- 0.40 mu g g(-1)), more studies are warranted to establish the biochemical mechanisms involved in this interaction. (c) 2007 Society of Chemical Industry.

Does mobilization for autologous stem cell transplantation damage stromal layer formation?

Autologous hematopoietic stem cell transplantation (HSCT) has proved efficient to treat hematological malignancies. However, some patients fail to mobilize HSCs. It is known that the microenvironment may undergo damage after allogeneic HSCT. However little is known about how chemotherapy and growth factors contribute to this damage. We studied the stromal layer formation(SLF) and velocity before and after HSC mobilization, through long-term bone marrow culture from 22 patients and 10 healthy donors. Patients` SLF was similar at pre- (12/22)and post-mobilization (9/20), however for controls this occurred more at pre- mobilization (9/10; p=0.03). SLF velocity was higher at pre than post-mobilization in both groups. Leukemias and multiple myeloma showed faster growth of SLF than lymphomas at post-mobilization, the latter being similar to controls. These findings could be explained by less uncommitted HSC in controls than patients at post-mobilization. Control HSCs may migrate more in response to mobilization, resulting in a reduced population by those cells.

Generation and Analysis of Interaction Energy Maps of p-Substituted Benzoic Acid [(5-Nitro-thiophen-2-yl)-methylene]-Hydrazides Active against MRSA

In this preliminary study eighteen p-substituted benzoic acid [(5-nitro-thiophen-2-yl)-methylene]-hydrazides with antimicrobial activity were evaluated against multidrug-resistant Staphylococcus aureus, correlating the three-dimensional characteristics of the ligands with their respective bioactivities. The computer programs Sybyl and CORINA were used, respectively, for the design and three-dimensional conversion of the ligands. Molecular interaction fields were calculated using GRID program. Calculations using Volsurf resulted in a statistically consistent model with 48 structural descriptors showing that hydrophobicity is a fundamental property in the analyzed biological response.

O/W Nanoemulsion After 15 Years of Preparation: A Suitable Vehicle for Pharmaceutical and Cosmetic Applications

The application of nanoemulsions is due to have good stability, uniform spreading and enhance active penetration upon skin. Nanometer emulsions can be obtained by low-energy emulsification method. The required hydrophilic and lipophilic balance indicates the better balance of emulsifier for optimum system emulsification. Emulsion stability is evidently controlled for the properties of the adsorbed layer formed in the surface of its globules, know as potential zeta. The aim of this work was to evaluate the oil/water nanoemulsion of formulation obtained after 15 years of preparation. The results suggested that the nanoemulsion have performed stability for many years.

Characteristics of undular hydraulic jumps: Experiments and analysis

The writers measured velocity, pressure and energy distributions, wavelengths, and wave amplitudes along undular jumps in a smooth rectangular channel 0.25 m wide. In each case the upstream flow was a fully developed shear flow. Analysis of the data shows that the jump has strong three-dimensional features and that the aspect ratio of the channel is an important parameter. Energy dissipation on the centerline is far from negligible and is largely constrained to the reach between the start of the lateral shock waves and the first wave crest of the jump, in which the boundary layer develops under a strong adverse pressure gradient. A Boussinesq-type solution of the free-surface profile, velocity, and energy and pressure distributions is developed and compared with the data. Limitations of the two-dimensional analysis are discussed.

Advice on exercise from a family physician can help sedentary patients to become active

Objectives: To test the effectiveness, in the setting of primary health care, of verbal advice on exercise from a family physician (FP) combined with supporting written information. Design: A controlled trial with subjects allocated to a control group or one of two intervention groups using a balanced design based on day of the week. Setting: Ten general practices in Perth, Western Australia. Subjects: All sedentary patients consulting an FP. Intervention: Verbal advice on exercise from the FP and a pamphlet on exercise mailed to the patient's home address within 2 days of his/her visit to the doctor. Main outcome measure: Level of physical activity at followup. Results: 6,351 adult patients attending an FP practice completed a screening questionnaire, and 763 sedentary adults were recruited to the project. The response to follow-up, via a postal survey at 1, 6, and 12 months after the index consultation was 70%, 60%, and 57%, respectively. At 1 month a subsample of the control and intervention subjects were contacted for a telephone interview to verify self-reported levels of activity (n = 136). Treating all nonresponders as sedentary, at 1 month significantly more subjects in the combined intervention groups reported doing some physical activity (40%) compared with the control group (31%). Similarly, at 6 months, 30% of the control group and 38% of the combined intervention groups were now active. There was very little change at followup at 12 months (31% control and 36% intervention groups, respectively). Conclusion: A simple intervention aimed at the promotion of physical activity to sedentary patients in general practice can help reduce inactivity.

Small molecular probes for G-protein-coupled C5a receptors: Conformationally constrained antagonists derived from the C terminus of the human plasma protein C5a

Activation of the human complement system of plasma proteins in response to infection or injury produces a 4-helix bundle glycoprotein (74 amino acids) known as C5a. C5a binds to G-protein-coupled receptors on cell surfaces triggering receptor-ligand internalization, signal transduction, and powerful inflammatory responses. Since excessive levels of C5a are associated with autoimmune and chronic inflammatory disorders, inhibitors of receptor activation may have therapeutic potential. We now report solution structures and receptor-binding and antagonist activities for some of the first small molecule antagonists of C5a derived from its hexapeptide C terminus. The antagonist NMe-Phe-Lys-Pro-D-Cha-Trp-D-Arg-CO2H (1) surprisingly shows an unusually well-defined solution structure as determined by H-1 NMR spectroscopy. This is one of the smallest acyclic peptides found to possess a defined solution conformation, which can be explained by the constraining role of intramolecular hydrogen bonding. NOE and coupling constant data, slow deuterium exchange, and a low dependence on temperature for the chemical shift of the D-Cha-NH strongly indicate an inverse gamma turn stabilized by a D-Cha-NH ... OC-Lys hydrogen bond. Smaller conformational populations are associated with a hydrogen bond between Trp-NH ... OC-Lys, defining a type II beta turn distorted by the inverse gamma turn incorporated within it. An excellent correlation between receptor-affinity and antagonist activity is indicated for a limited set of synthetic peptides. Conversion of the C-terminal carboxylate of 1 to an amide decreases antagonist potency 5-fold, but potency is increased up to 10-fold over 1 if the amide bond is made between the C-terminal carboxylate and a Lys/Orn side chain to form a cyclic analogue. The solution structure of cycle 6 also shows gamma and beta turns; however, the latter occurs in a different position, and there are clear conformational changes in 6 vs 1 that result in enhanced activity. These results indicate that potent C5a antagonists can be developed by targeting site 2 alone of the C5a receptor and define a novel pharmacophore for developing powerful receptor probes or drug candidates.