Identification of Mechanical Systems through Kautz Filter

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Adaptive filter feature identification for structural health monitoring in an aeronautical panel

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dosimetric properties of UV irradiated calcium co-doped borate glass-ceramic

The thermoluminescence (TL) response of Dy and Li doped 20CaB(4)O(7)-80CaB(2)O(4) (Wt%) glass-ceramic irradiated with ultraviolet (UV) radiation was studied. In order to act as TL activator ions, the Dy and Li ions were included in the matrix during the melting process to increase its TL efficiency. A single crystalline CaB2O4 phase was present in the glass-ceramic as determined by X-ray diffraction (XRD). The glass-ceramic 20CaB(4)O(7)-80CaB(2)O(4):Dy,Li wt% (named 20CBO7:Dy,Li) is a newly prepared TL material. Its thermoluminescent dosimetric characteristics have shown a linear response under UV radiation exposure and a good TL signal reproducibility, thus proving to be a promising material for using as an ultraviolet radiation dosimeter. (C) 2007 Elsevier B.V. All rights reserved.

Caracterização de resíduo sólido formado em biodiesel de sebo bovino

Biodiesel production has increased over the last decade because of the benefits associated with this fuel, including renewability, domestic feedstock, lower toxicity, and biodegradability. From 2008, the use of beef tallow as a feedstock for biodiesel production in Brazil has increased in significance, representing the second largest source of biodiesel, after soybeans. However, the performance of biodiesel in cold weather conditions is worse than diesel because of deposition of insoluble at low temperatures, accelerating the plugging of fuel filters and injectors of the vehicle engine. Studies have been conducted on beef tallow biodiesel, mostly related to the properties of thermal and oxidative stability. However, few studies have described the nature of the precipitate formed and its influence on product quality. Research suggests that the cause of deposition is related to the nature of saturated esters and monoacylglycerols as inducing agents. This study monitored the levels of mono-, diand triacylglycerols, the oxidation stability and the cold filter plugging point (CFPP) in beef tallow biodiesel samples from two commercial producers in Brazil for a period of twelve months. Filtered precipitates were analyzed by comparative techniques of GCFID, HPLC-UV/VIS, HPLC-MS-IT-TOF and TG to verify the nature, using monopalmitin and monostearin as reference standards. The formation of precipitate reduced the levels of monoacylglycerols in the beef tallow biodiesel. GC-FID and LCMS- IT-TOF results confirmed the nature of the deposit as saturated monoacylglycerols, predominantly monostearin and monopalmitin as the second major component. Moreover the TG analysis of the residue indicated similar thermal decomposition of the reference standards. The precipitate did not affect the oxidation stability of beef tallow biodiesel and the CFPP characteristic of blends up B60. However, the presence of iron reduced significantly the oxidation stability of biodiesel

Caracterização de resíduo sólido formado em biodiesel de sebo bovino

Biodiesel production has increased over the last decade because of the benefits associated with this fuel, including renewability, domestic feedstock, lower toxicity, and biodegradability. From 2008, the use of beef tallow as a feedstock for biodiesel production in Brazil has increased in significance, representing the second largest source of biodiesel, after soybeans. However, the performance of biodiesel in cold weather conditions is worse than diesel because of deposition of insoluble at low temperatures, accelerating the plugging of fuel filters and injectors of the vehicle engine. Studies have been conducted on beef tallow biodiesel, mostly related to the properties of thermal and oxidative stability. However, few studies have described the nature of the precipitate formed and its influence on product quality. Research suggests that the cause of deposition is related to the nature of saturated esters and monoacylglycerols as inducing agents. This study monitored the levels of mono-, diand triacylglycerols, the oxidation stability and the cold filter plugging point (CFPP) in beef tallow biodiesel samples from two commercial producers in Brazil for a period of twelve months. Filtered precipitates were analyzed by comparative techniques of GCFID, HPLC-UV/VIS, HPLC-MS-IT-TOF and TG to verify the nature, using monopalmitin and monostearin as reference standards. The formation of precipitate reduced the levels of monoacylglycerols in the beef tallow biodiesel. GC-FID and LCMS- IT-TOF results confirmed the nature of the deposit as saturated monoacylglycerols, predominantly monostearin and monopalmitin as the second major component. Moreover the TG analysis of the residue indicated similar thermal decomposition of the reference standards. The precipitate did not affect the oxidation stability of beef tallow biodiesel and the CFPP characteristic of blends up B60. However, the presence of iron reduced significantly the oxidation stability of biodiesel

Endovascular Treatment of Late Aortic Perforation due to Vena Cava Filter

Perforation of inferior vena cava (IVC) by filter struts ranges from 9% to 24%, and clinical sequelae and complications are unpredictable. The aim of this article was to report an unusual case of late complication of IVC filter that caused an IVC wall perforation and penetration of the filter's hooks in the aorta, which was treated by endovascular procedure. Molding strut tip by balloon angioplasty, its accommodation with a bare stent, and its coverage and protection with an endoprosthesis is probably the first technique reported so far in this situation.

Effects of Coccoloba uvifera L. on UV-stimulated melanocytes

Exposure to ultraviolet (UV) radiation induces generation of reactive oxygen species, production of proinflammatory cytokines and melanocyte-stimulating hormone (MSH) as well as increase in tyrosinase activity. The potential photoprotective effects of Coccoloba uvifera extract (CUE) were evaluated in UV-stimulated melanocytes.Human epidermal melanocytes were used as an in vitro model to evaluate the effects of CUE on the production interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF-alpha), and alpha-MSH under basal and UV-stimulated conditions. Antioxidant and anti-tyrosinase activities were also evaluated in membrane lipid peroxidation and mushroom tyrosinase assay, respectively.Coccoloba uvifera L. showed antioxidant and anti-tyrosinase activities and also inhibited the production of IL-1 alpha, TNF-alpha and alpha-MSH in melanocytes subjected to UV radiation (P < 0.01). Moreover, CUE inhibited the activity of tyrosine kinase in cell culture under basal and UV radiation conditions (P < 0.001), corroborating the findings of the mushroom tyrosinase assay.This study supports the photoprotective potential of CUE.

The influence of UV-C irradiation on the properties of thermoplastic starch and polycaprolactone biocomposite with sisal bleached fibers

The effect of UV-C irradiation of the TPS and PCL biocomposites with sisal bleached fibers was investigated. The biocomposite was UV-C irradiated at room temperature under air atmosphere. The structural and morphological changes produced when the films were exposed to UV irradiation for 142 h, were monitored using Scanning Electron Microscopy (SEM), Mechanical Tensile Tests, Differential Scanning Calorimetry (DSC), X-ray diffraction, Thermogravimetric analysis (TGA), and Fourier transform infra-red analysis (FTIR). Addition of 5-10% fibers in composites exhibited improved mechanical and thermal properties attributed to more efficient dispersibility of fiber in the matrix and good compatibility between fibers and the matrix polymer, however, after irradiated, the tensile properties decreased due to chain scission. The samples of irradiated PCL and IFS showed crystallinity increase, whereas the blend and composites showed a decrease in crystallinity. The DSC and X-ray diffraction studies suggested interaction between polymers in the blend via carboxyl groups in thermoplastic starch-PCL and hydroxyl groups in fibers. (C) 2011 Elsevier Ltd. All rights reserved.

Structural and morphological changes in Poly(caprolactone)/poly(vinyl chloride) blends caused by UV irradiation

Films made from a blend of poly(epsilon-caprolactone) and poly(vinyl chloride) (PCL/PVC) retained high crystallinity in a segregated PCL phase. Structural and morphological changes produced when the films were exposed to high potency ultraviolet (UV) irradiation for 10 h were measured by UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). They were different to those observed with homopolymer PCL and PVC films treated under the same conditions. The FTIR spectra of the PCL/PVC blend suggest that blending decreased the susceptibility of the PCL to crystallize when irradiated. Similarly, although scanning electron micrographs of PCL showed evidence of growth of crystalline domains, particularly after UV irradiation, the images of PCL/PVC were fairly featureless. It is apparent that the degradation behavior is strongly influenced by the interaction of the two polymers in the amorphous phase.

Towards a UV completion of chameleons in string theory

Chameleons are scalar fields that couple directly to ordinary matter with gravitational strength, but which nevertheless evade the stringent constraints on tests of gravity because of properties they acquire in the presence of high ambient matter density. Chameleon theories were originally constructed in a bottom-up, phenomenological fashion, with potentials and matter couplings designed to hide the scalar from experiments. In this paper, we attempt to embed the chameleon scenario within string compactifications, thus UV completing the scenario. We look for stabilized potentials that can realize a screening mechanism, and we find that the volume modulus rather generically works as a chameleon, and in fact the supersymmetric potential used by Kachru, Kallosh, Linde and Trivedi (KKLT) is an example of this type. We consider all constraints from tests of gravity, allowing us to put experimental constraints on the KKLT parameters.

Influence of Hydrothermal Synthesis Conditions and Device Configuration on the Photoresponse of UV Sensors Based on ZnO Nanorods

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

SAXS and UV-Vis combined to Quick-XAFS monitoring of ZnO nanoparticles formation and growth

Time-resolved X-ray absorption-fine structure (Quick-XAFS) and UV-Vis absorption spectroscopies were combined for monitoring simultaneously the time evolution of Zn-based species and ZnO quantum dot (Qdot) formation and growth during the sol-gel synthesis from zinc oxy-acetate precursor solution. The time evolution of the nanostructural features of colloidal suspension was independently monitored in situ by small angle X-ray scattering (SAXS). In both cases, the monitoring was initialized just after the addition of NaOH solution (B = [OH]/[Zn] = 0.5) to the precursor solution at 40 degrees C. Combined time-resolved Quick-XAFS and UV-Vis data showed that the formation of ZnO colloids from the zinc oxy-acetate consumption achieves a quasi-steady-state chemical equilibrium in less than 200s. Afterwards, the comparison of the ZnO Qdots size and Guinier gyration radius evidences a limited aggregation process coupled to the Qdots growth. The analysis of the experimental results demonstrates that the nanocrystal coalescence and Ostwald ripening control the kinetics of the Qdot growth.

QEXAFS and UV/Vis Simultaneous Monitoring of the TiO2-Nanoparticles Formation by Hydrolytic Sol-Gel Route

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

On the photoluminescence behavior of samarium-doped strontium titanate nanostructures under UV light. A structural and electronic understanding

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Development of an HPLC-UV/Vis method for the determination of dyes in a gasoline sample employing different pre-treatments

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)