Influence of cerium (IV) ions on the inorganic and organic phase for preparation of a siloxane-PMMA based film on tin plate substrate

Tinplate is one of the most widely used food canning materials, however, there are significant problems related to the use of tinplate cans, such as alterations in sensory features affecting food quality and corrosion phenomena of the canning material. To avoid corrosion problems different methods have been used for the passivation of tinplate such protective lacquers or different kinds of corrosion inhibitors (chromate and dichromate). However, chromates and dichromates are extremely harmful to the environment and can cause carcinogenic tumors to humans. An option, protective coatings obtained by the sol-gel process, act as a physical barrier, which isolates the surface of metal protecting from the corrosive agents. The aim of this work is to study the influence of addition of cerium (IV) ions in the inorganic and organic part of sol-gel processing in the formation of hybrid coatings based on siloxane-PMMA on tin plate. The coatings were obtained by dip-coating technique and evaluated by open circuit and impedance measurements, linear polarization and polarization curves obtained in 3.5% NaCl solution. The results have clearly shown the improvement on the protective properties of the Ce 4+ modified film when added into the organic phase, which can be due to the formation of a more uniform and densely reticulated siloxane-PMMA film. © 2009 by NACE International.

Effect of plastic film mulch on the production of butterhead lettuce cultivars under protected cultivation

The study was performed in a greenhouse with the aim of evaluating the production of butterhead lettuce cultivars with and without plastic film mulch in the summer. The cultivars studied were 'Elisa', 'Lídia', 'Herman' and 'Luísa'. The experimental design was a split plot, in which the main plot was plastic film mulch (with or without black polyethylene film) and the subplots were the cultivars, with three repetitions. The seedlings were grown in Styrofoam trays of 288 cells and transplanted 25 days after seeding in a space of 25 × 25 cm. Harvests were carried out 45 days after transplanting and the following variables were determined: fresh and dry weights of the aerial part, number of leaves per plant, plant height and the longitudinal and transverse diameters of the plant. Significant differences were found only among the cultivars for the characteristics studied, with no cover × cultivar interaction. Fresh weight of the aerial part of 'Lídia' (270.9 g) was greater than that of 'Herman' (142.5 g), but did not differ from those of 'Luísa' (229.8 g) or 'Elisa' (204.8). The dry weight of the aerial part of 'Lídia' (12.4 g) differed statistically only with respect to that of 'Herman' (7.9 g). The cultivars 'Luísa' and 'Elisa' had an aerial part dry weight of 11.4 and 11.2 g, respectively. The number of leaves per plant of the cultivars 'Luísa' (45.1) and 'Elisa' (43.0) was higher than for 'Herman' (24.05), but did not differ from that of the cultivar 'Lídia' (39.5). The mean transverse and longitudinal diameters, as well as the mean height of the plants, showed that 'Lídia', 'Elisa' and 'Luísa' had the greatest values. The cultivars 'Lídia', 'Elisa' and 'Luísa' were the most productive and plastic film mulch had no effect on lettuce production under protected cultivation.

A comparison of the film thickness of two adhesive luting agents and the effect of thermocycling on their microTBs to feldspathic ceramic.

The aim of the present study was to evaluate the effect of thermocycling (TC) on the microtensile bond strength (microTBS) of two luting agents to feldspathic ceramic and to measure their film thickness (FT). For the microTBS test, sixteen blocks (6.4 x 6.4 x 4.8 mm) were fabricated using a feldspathic ceramic, etched with 10% hydrofluoric acid, rinsed and treated with the silane agent. The ceramic blocks were divided into two groups (n= 8): Gr1: dual-cured resin cement and Gr2: flowable resin. The luting agents were applied on the treated surfaces. Microsticks (1 +/-0. 1mm2) were prepared and stored under two conditions: dry, specimens immediately submitted to the microTBS test, and TC (6,000 cycles; 5 degrees C-55 degrees C). The microTBS was evaluated using a universal testing machine (1 mm/min). The microTBS data (MPa) were submitted to two-way ANOVA and Tukey' test (5%). For the FT test (ISO 4049), 0.05 ml of each luting agent (n=8) was pressed between two Mylar-covered glass plates (150 N) for 180 seconds and light polymerized. FT was measured using a digital paquimeter (Model 727-2001). The data (mm) were submitted to one-way ANOVA. The luting cement did not influence the microTBS results (p= 0.4467). Higher microtensile bond values were found after TC (20.5 +/- 8.6 MPa) compared to the dry condition (13.9 +/- 4. 7MPa), for both luting agents. The luting agents presented similar film thicknesses: Gr1- 0.052 +/- 0.016 mm; Gr2-0.041 +/- 0.003 mm. The luting agents presented similar film thickness and microTBS values, in dry and TC conditions and TC increased the bond strength regardless of the luting agent.

Effect of diamond-like carbon thin film coated acrylic resin on candida albicans biofilm formation

Purpose: The purpose of this study was to evaluate the effect of diamond-like carbon thin films doped and undoped with silver nanoparticles coating poly(methyl methacrylate) (PMMA) on Candida albicans biofilm formation. The control of biofilm formation is important to prevent oral diseases in denture users. Materials and Methods: Forty-five PMMA disks were obtained, finished, cleaned in an ultrasonic bath, and divided into three groups: Gc, no surface coating (control group); Gdlc, coated with diamond-like carbon film; and Gag, coated with diamond-like carbon film doped with silver nanoparticles. The films were deposited using a reactive magnetron sputtering system (physical vapor deposition process). The specimens were characterized by optical profilometry, atomic force microscopy, and Rutherford backscattering spectroscopy analyses that determined differences in chemical composition and morphological structure. Following sterilization of the specimens by γ-ray irradiation, C. albicans (ATCC 18804) biofilms were formed by immersion in 2 ml of Sabouraud dextrose broth inoculated with a standardized fungal suspension. After 24 hours, the number of colony forming units (cfu) per specimen was counted. Data concerning biofilm formation were analyzed using ANOVA and the Tukey test (p < 0.05). Results: C. albicans biofilm formation was significantly influenced by the films (p < 0.00001), reducing the number of cfu, while not affecting the roughness parameters (p > 0.05). The Tukey test showed no significant difference between Gdlc and Gag. Films deposited were extremely thin (∼50 nm). The silver particles presented a diameter between 60 and 120 nm and regular distribution throughout the film surface (to Gag). Conclusion: Diamond-like carbon films, doped or undoped with silver nanoparticles, coating the base of PMMA-based dentures could be an alternative procedure for preventing candidosis in denture users. © 2013 by the American College of Prosthodontists.

Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0-14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia. © 2013 Elsevier B.V. All rights reserved.

An Electrochemical Sensor for Reducing Sugars Based on a Glassy Carbon Electrode Modified with Electropolymerized Molecularly Imprinted Poly-o-phenylenediamine Film

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

Electrochemical Properties of the Oxo-Manganese-Phenanthroline Complex Immobilized on Ion-Exchange Polymeric Film and Its Application as Biomimetic Sensor for Sulfite Ions

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

Protective film growth on tin in perchlorate and citric acid electrolytes

Voltammetry has been employed to study the influence of systematic additions of citric acid on the E-I curves of Tin in 0.5 M NaClO4, in order to verify the film growth in the presence of the organic acid and the inhibition of the pitting corrosion of the metal. The minimum concentration of the organic acid needed to change the GI curves is 10(-2) M, in the pH range 1.0-4.0. At pH 3.0 and 4.0, the scan rate dependence on current density, in the potential region of formation and reduction of the film, showed that in a first stage adsorption occurs. In a second stage, the v(1/2) dependence found can he explained by ohmic resistance control. The formation of tin/citric acid complexes, 10(-2) M, is suggested. The pitting inhibition may be due to the formation of a mixed layer of tin in citric acid concentrations higher than 10(-2) oxide and tin citrate complexes on the electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.

Carbon Film Coating of Abutment Surfaces: Effect on the Abutment Screw Removal Torque

Purpose: To evaluate the effect of diamond-like carbon (DLC) coating of prefabricated implant abutment on screw removal torque (RT) before and after mechanical cycling (MC).Materials and Methods: Fifty-four abutments for external-hex implants were divided among 6 groups (n = 9): S, straight abutment (control); SC, straight coated abutment; SCy, straight abutment and MC; SCCy, straight coated abutment and MC; ACy, angled abutment and MC; and ACCy, angled coated abutment and MC. The abutments were attached to the implants by a titanium screw. RT values were measured and registered. Data (in Newton centimeter) were analyzed with analysis of variance and Dunnet test (alpha = 0.05).Results: RT values were significantly affected by MC (P = 0.001) and the interaction between DLC coating and MC (P = 0.038). SCy and ACy showed the lowest RT values, statistically different from the control. The abutment coated groups had no statistical difference compared with the control. Scanning electron microscopy analysis showed DLC film with a thickness of 3 mm uniformly coating the hexagonal abutment.Conclusion: DLC film deposited on the abutment can be used as an alternative procedure to reduce abutment screw loosening.

Tetraethylortossilicate plasma thin film with hydrophilic and hydrophobic characteristics: Use on passive mixers

This work aims to obtain plasma thin film composites with hydrophobic/hydrophilic alternated regions, which are useful for the production of miniaturized mixers. These regions were acquired by two different strategies: either the codeposition of TEOS and HFE plasma thin films or the exposition of TEOS plasma films to ultraviolet radiation (UVA and UVC). These films were characterized by several chemical and physical techniques. The refractive indexes vary from 1.4 to 1.7; infrared and photoelectron spectroscopy detect Si-O-Si and CHn species. Silicone-like structures with high or low number of amorphous carbon microparticles and with fluorinated organic clusters were produced. Cluster dimensions were in the 1-5 mm range and they are made of graphite or COF (carbon/oxygen/fluorine) compounds. Scanning electron and optical microscopy showed rough surfaces. Water contact angles were 90º; however, for TEOS films that value changed after 6 hr of UVC exposure. Moreover, after UV exposure, organic polar compounds could be adsorbed in those films and water was not. The passive mixer performance was simulated using the FemLab 3.2® program and was tested with 20 nm thick films on a silicon wafer, showing the capacity of these films to be used in such devices.

Effects of polyethylene film wrap on cooler shrink and the microbial status of beef carcasses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ozone and nitrogen dioxide gas sensor based on a nanostructured SrTi0.85Fe0.15O3 thin film

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Film based on Y2O3: Eu3+ (5 mol% of Eu3+) for flat panel display

This paper reports on Y2O3:Eu3+ containing 1 mol% of Ag-0 nanoparticle films recovered with a SiO2 layer by using glass foil as a substrate for a possible optical display device application. The obtained film showed an intense emission at 612 nm due to the Eu3+ 5D0 -> F-7(2) hypersensitive transition, a high transmittance in that emission range, an excellent optical quality, and a high absorption only below 300 nm. Moreover, despite the presence of the SiO2 layer used to improve the phosphor adhesion on Corning (R) foil substrates, the intensity ratios between the emissions assigned to Eu3+ D-5(0) -> F-7(2) (dipole electric transition) and D-5(0) -> F-7(1) (dipole magnetic transition) were not affected by it. The x and y coordinate values found in the 1931 Commission Internationale de l'Eclairage Chromaticity Diagram for this film reveal that it has a suitable pure red color emission for optical displays devices. (C) 2012 Elsevier B. V. All rights reserved.

Influence of the Sol-Gel pH Process and Compact Film on the Efficiency of TiO2-Based Dye-Sensitized Solar Cells

The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2 nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2 films. Nanoparticles prepared under acid pH exhibit smaller particle size and higher surface area, which result in higher dye loadings and better short-circuit current densities than DSCs based on alkaline TiO2-processed films. On the other hand, the product of charge collection and separation quantum yields in films with TiO2 obtained by alkaline hydrolysis is c. a. 27% higher than for the acid TiO2 films. The combination of acid and alkaline TiO2 nanoparticles as mesoporous layer in DSCs results in a synergic effect with overall efficiencies up to 6.3%, which is better than the results found for devices employing one of the nanoparticles separately. These distinct nanoparticles can be also combined by using the layer-by-layer technique (LbL) to prepare compact TiO2 films applied before the mesoporous layer. DSCs employing photoanodes with 30 TiO2 bilayers have shown efficiencies up to 12% higher than the nontreated photoanode ones. These results can be conveniently used to develop optimized synthetic procedures of TiO2 nanoparticles for several dye-sensitized solar cell applications.

The influence of film morphology on solution processed organic field-effect transistors

Organic field-effect transistors (OFETs) are becoming interesting owing to their prospective application as cheap, bendable and light weight electronic devices rnlike flexible displays. However, the bottleneck of OFETs is their typically low charge carrier mobilities. An effective and crucial route towards circumventing thisrnhurdle is the control of organic semiconductor thin film morphology which critically determine charge carrier transport. In this work, the influence of film morphologyrnis highlighted together with its impact on OFET transistor performance.