Photoelectrocatalytic degradation of Remazol Brilliant Orange 3R on titanium dioxide thin-film electrodes

Degradation of reactive dye Remazol Brilliant Orange 3R (RBO) has been performed using photoeletrocatalysis. A biased potential is applied across a titanium dioxide thin-film photoelectrode illuminated by UV light. It is suggested that charges photogenerated at the electrode surface give rise to chlorine generation and powerful oxidants (OH) that causes the dye solution to decolorize. Rate constants calculated from color decay versus time reveal a first-order reaction up to 5.0×10-5 mol l-1 in dye concentration. The best experimental conditions were found to be pH 6.0 and 1.0 mol l-1 NaCl when the photoelectrode was biased at +1V (versus SCE). Almost complete mineralization of the dye content (70% TOC reduction) was achieved in a 3-h period using these conditions. Effects of other electrolytes, dye concentration and applied potentials also have been investigated and are discussed. © 2003 Elsevier Science B.V. All rights reserved.

Flow injection amperometric determination of persulfate in cosmetic products using a Prussian Blue film-modified electrode

A flow-injection system with a glassy carbon disk electrode modified with Prussian Blue film is proposed for the determination of persulfate in commercial samples of hair bleaching boosters by amperometry. The detection was obtained by chronoamperometric technique and the sample is injected into the electrochemical cell in a wall jet configuration. Potassium chloride at concentration of 0.1 mol L-1 acted as sample carrier at a flow rate of 4.0 mL min-1 and supporting-electrolyte. For 0.025 V (vs. Ag/AgCl) applied voltage, the proposed system handles ca. 160 samples per hour (1.0 10-4 - 1.0 10-3 mol L-1 of persulfate), consuming about 200 μL sample and 11 mg KCl per determination. Typical linear correlations between electrocatalytic current and persulfate concentration was ca. 0.9998. The detection limit is 9.0 10-5 mol L-1 and the calculated amperometric sensibility 3.6 103 μA L mol -1. Relative standard deviation (n =12) of a 1.0 10-4 mol L-1 sample is about 2.2%. The method was applied to persulfate determination in commercial hair-bleaching samples and results are in agreement with those obtained by titrimetry at 95% confidence level and good recoveries (95 - 112%) of spiked samples were found. © 2003 by MDPI.

Behavior of bromide in the photoelectrocatalytic process and bromine generation using nanoporous titanium dioxide thin-film electrodes

In this study, the photoelectrocatalytic behavior of bromide and generation of bromine using TiO2 was investigated in the separate anode and cathode reaction chambers. Our results show that the generation of bromine begins around a flatband potential of -0.34 V vs. standard calomel electrode (SCE) at pH 3.0 under UV illumination and increases with an increase in positive potential, finally reaching a steady-state concentration at 1.0 V vs. SCE. Maximum bromine formation occurs over the range of pH 4-6, decreasing sharply at conditions where the pH > 7. © 2003 Elsevier Ltd. All rights reserved.

Photoelectrocatalytic production of active chlorine on nanocrystalline titanium dioxide thin-film electrodes

The production of chlorine and hypochlorite is of great economical and technological interest due to their large-scale use in many kinds of commercial applications. Yet, the current processes are not without problems such as inevitable side reactions and the high cost of production. This work reports the photoelectrocatalytic oxidation of chloride ions to free chlorine as it has been investigated by using titanium dioxide (TiO2) and several metal-doped titanium dioxide (M-TiO2) material electrodes. An average concentration of 800 mg L-1 of free chlorine was obtained in an open-air reactor using a TiO2 thin-film electrode biased at +1.0 V (SCE) and illuminated by UV light. The M-doped electrodes have performed poorly compared with the pure TiO2 counterpart. Test solutions containing 0.05 mol L-1 NaCl pH 2.0-4.0 were found to be the best conditions for fast production of free chlorine. A complete investigation of all parameters that influence the global process of chlorine production by the photoelectrocatalytic method such as applied potential, concentration of NaCl, pH solution, and time is presented in detail. In addition, photocurrent vs potential curves and the reaction order are also discussed.

Dielectric and viscoelastic properties of cross-linked polyethylene aged under multi stressing conditions

Different measurements were performed in cross-linked polyethylene (XLPE) employed as insulating material in coaxial cables that were field-aged and laboratory-aged under multi-stressing conditions at room temperature. Samples were peeled from the XLPE cable insulation in three different positions: just below the external semiconductor layer (outer layer), in the middle (middle layer) and just above the internal semiconductor layer of the cable (inner layer). The imaginary part of the electric susceptibility showed three peaks that obey the Dissado-Hill model. For laboratory-aged XLPE samples peeled from the inner and from the middle positions the peak at very low frequency region increased while in samples from the outer position a quasi-DC conduction process was observed. In medium frequency range a broadening of the peak was observed for all samples. Viscoelastic properties determined through dynamic mechanical analysis suggested that the aging generates processes that promoted changes of the crystallinity and the cross-linking degrees of the polymer. Fourier transform infrared spectroscopy (FTIR) measurements revealed an increase of oxidation products (esters), evidence of polar residues of the bow-tie tree and the presence of cross-linking by-products (acetophenone). Optical and scanning electronic microscope (SEM) measurements in aged samples revealed the existence of voids and bow-tie trees that were formed during aging in the middle region of the cable.

Porous polyethylene for tissue engineering applications in diabetic rats treated with calcitonin: Histomorphometric analysis

Purpose: The purpose of this work was to study the bone tissue reaction after porous polyethylene (Polipore) implantation into surgical defects in the parietal bones of rats with streptozotocin-induced diabetes, treated with salmon calcitonin. Materials and Methods: Porous polyethylene implants were placed in bone defects created in 36 adult female rats. The rats were divided into 3 equal groups: diabetic treated with calcitonin (DCa), diabetic (D), and control (C). The animals of the DCa group received applications of salmon calcitonin on alternating days immediately after the surgery until sacrifice. The rats were sacrificed after 15, 30, 60, and 90 days, and the defects were examined histologically and statistically through histomorphometric analysis. Results: Histomorphometric analysis showed that there was no statistically significant difference in the mean quantity of inflammatory cells among all study groups after 15 and 90 days. At 30 days, a statistically significant difference was observed between the D and C groups and the D and DCa groups. At 60 days, there was no statistically significant difference between the D and DCa groups. Discussion: Porous polyethylene can be considered an option for implant material when there are investigations that prove its biocompatibility and stability in the host tissues. Salmon calcitonin positively aided the bone repair and attenuated the inflammatory response until 30 days after the surgery. Conclusion: Porous polyethylene was tolerated by the host tissues in all groups, and moderate chronic inflammatory reaction was observed up to the 90-day period. Salmon calcitonin attenuated the inflammatory response up until 30 days.

Respiratory and storage behavior of fresh cut 'Tommy Atkins' mango

The respiratory and storage behavior of fresh cut 'Tommy Atkins' mango, naturally ripened (NR) or with use of ethylene (RE), were studied. Fruits were selected, washed and disinfected (200 mgCl.L-1) and stored for 12 hours at 10°C. After this period, they were processed under hygienic conditions at 10°C, packaged in polyethylene terephthalate (PET) trays or in styrofoam trays wrapped with stretchable polyvinyl chloride (PVC) film and stored for up to 15 days at 3°C. The products were evaluated regarding the evolution of internal atmosphere in the packing (O2 and CO 2), development of weight, appearance, shelf life and consumer acceptability. The respiratory rate was measured before and after processing every two hours. The yield of 'Tommy Atkins' mango to produce fresh cut product was 48.09±0.95%. Increase of the respiration rate of both mango samples was verified one hour after the preparation (NR = 17.75 mL CO 2.kg-1.h-1; RE = 28.29 mL CO 2.kg-1.h-1), followed by stabilization at 3.76 and 8.07 mL CO2/kg.h, respectively. The percentage of O2 in packages was stable in all treatments, 15-20% in PVC trays, 18-20% in PET tray. The percentage of CO2 was steady around 1.5-2.5%. The products lost fresh mass during the storage, from 0.06% to 0.30% for PET trays and from 0.15% to 1.61% for trays covered with PVC. The appearance was considered appropriate for commercialization until the 13th day, whereas product from mangoes ripened with application of ethylene was for 11 days, presenting browning in the external surface. The naturally ripened mango presented the best flavor and consumer preference in relation to the mango ripened with application of ethylene for 11 days of storage. The control of hygienic conditions during the production and storage was good and with safety for until 10 days.

Double optical monitoring of time-dependent film formation

A brief overview of optical monitoring for vacuum and wet bench film deposition processes is presented. Interferometric and polarimetric measurements are combined with regard to simultaneous real-time monitoring of refractive index and physical thickness. Monitor stability and accuracy are verified with transparent oil standards. This double optical technique is applied to dip coating with a multi-component Zirconyl Chloride aqueous solution, whose time varying refractive index and physical thickness curves indicate significant sensitivity to changes of film flow properties during the process.

Production of four cultivars of iceberg lettuce, under protected cultivation, with and without black polyethylene ground cover

The aim of the work was to evaluate the performance of four cultivars of iceberg lettuce, in a greenhouse, with and without ground cover. The experimental design adopted was that of subdivided parcels, where parcels were provided with and without ground cover consisting of black polyethylene and the subparcels consisted of the cultivars. There were three repetitions per treatment and six central plants of each parcel were evaluated. Drip irrigation was utilized. The cultivars studied were: 'Laurel', 'AF-389', 'Mayara' and 'Tainá'. The seeds were planted in Styrofoam trays with 288 cells containing the substrate Plantmax Hortaliças® A. The trays were kept in a greenhouse until transplanting, 25 days after seeding. The parameters examined were: fresh weight of the aerial part per plant, longitudinal (DL) and transverse (DT) diameters of the head, height of the plant and mean number of leaves per plant. Only among the cultivars there were significant differences in transverse and longitudinal diameters of the head and height of the plant. No significant interactions were detected between ground cover and cultivars. With regard to longitudinal and transverse diameters, 'AF-839' (DL = 27.11 cm; DT = 24.53 cm) showed smaller diameters than those of 'Laurel' (DL = 31.13 cm; DT = 30.55 cm), but did not differ from the other cultivars. In regard to height of the plants, 'Laurel' (20.66 cm) had the greatest value and 'AF-839' (16.02 cm) the lowest. The cultivars did not differ with respect to mean number of leaves and fresh weight of the aerial part of the plant. It is concluded that there were no significant differences in the cultivation of the iceberg lettuce with and without ground cover. The cultivar 'Laurel' stood out with respect to longitudinal and transverse diameters and height of the plant, only differing from the 'AF-839' with regard to the diameters.

Effect of resin luting film thickness on fracture resistance of a ceramic cemented to dentin

Purpose: The aim of this study was to evaluate the fracture resistance of ceramic plates cemented to dentin as a function of the resin cement film thickness. Materials and Methods: Ceramic plates (1 and 2 mm thicknesses) were cemented to bovine dentin using resin composite cement. The film thicknesses used were approximately 100, 200, and 300 μm. Noncemented ceramic plates were used as control. Fracture loads (N) were obtained by compressing a steel indenter in the center of the ceramic plates. ANOVA and Tukey tests (α = 0.05) were used for each ceramic thickness to compare fracture loads among resin cement films used. Results: Mean fracture load (N) for 1-mm ceramic plates were: control - 26 (7); 100 μm - 743 (150); 200 μm - 865 (105); 300 μm - 982 (226). Test groups were significantly different from the control group; there was a statistical difference in fracture load between groups with 100 and 300 μm film thicknesses (p < 0.01). Mean fracture load for 2-mm ceramic plates were: control - 214 (111); 100 μm - 1096 (341); 200 μm - 1067 (226); 300 μm - 1351 (269). Tested groups were also significantly different from the control group (p < 0.01). No statistical difference was shown among different film thicknesses. Conclusions: Unluted specimens presented significantly lower fracture resistance than luted specimens. Higher cement film thickness resulted in increased fracture resistance for the 1-mm ceramic plates. Film thickness did not influence the fracture resistance of 2-mm porcelain plates. Copyright © 2007 by The American College of Prosthodontists.

Preparation and characterization of castor oil-based polyurethane/poly(o- methoxyaniline) blend film

Blends made up of castor oil-based polyurethane (PU) and poly(o-methoxyaniline) (POMA) were obtained in the form of films by casting and characterized by FTIR, UV-Vis-NIR spectroscopy, and electrical conductivity measurements. Doping was carried out by immersing the films in 1.0M HCl aqueous solution. Chemical bonds between NCO group of PU and NH group of POMA were observed by means of FTIR spectra. The UV-Vis-NIR spectra indicated that the presence of the PU in the blend does not affect doping and formation of the POMA phase. The electrical conductivity research was in the range of 10-3 S/cm. © 2007 Wiley Periodicals, Inc.

Application of non-isothermal cure kinetics on the interaction of poly(ethylene terephthalate) - Alkyd resin paints

Samples of paint (P), reused PET (PET-R) and paint/PET-R mixtures (PPET-R) were evaluated using DSC to verify their physical-chemical properties and thermal behavior. Films from paints and PPET-R are visually similar. It was possible to establish that the maximum amount of PET-R that can be added to paint without significantly altering its filming properties is 2%. The cure process (80-203°C) was identified through DSC curves. The kinetic parameters, activation energy (E a) and Arrhenius parameters (A) for the samples containing 0.5 to 1% of PET-R, were calculated using the Flynn-Wall-Ozawa isoconversional method. It was observed that for greater amounts of PET-R added, there is a decrease in the E a values for the cure process. A Kinetic compensation effect (KCE), represented by the equation InA=-2.70+0.31E a was observed for all the samples. The most suitable kinetic model to describe this cure process is the autocatalytic Šesták-Berggreen, model applied to heterogeneous systems. © 2007 Springer Science+Business Media, LLC.

Polyethylene gel in the subcutaneous tissue of rats: Histopathologic and systemic evaluation

Purpose: To evaluate the histological and systemic response to subcutaneous injection of polyethylene gel in rats. Methods: Twenty-one white male rats were divided into 3 groups (G): G1 and G2 received subcutaneous polyethylene gel injection in the dorsal midline and were sacrificed at 30 and 60 postoperative days, respectively. G3 was not exposed to the polyethylene gel and was sacrificed after 60 days. Blood levels of lactate dehydrogenase (LDH), creatine kinase (CK), and alkaline phosphatase (ALP) were evaluated. The heart, kidney, liver, adrenal gland, injection site, and adjacent tissues were histologically examined. The results were submitted to statistical analysis. Results: There was no clinical evidence of extrusion, reduction of the injected volume, or abnormalities in the adjacent tissues. Blood levels of CK and LDH were normal and similar in all groups. ALP levels were significantly lower in G2 than in G1 and G3. The systemic organs were normal on histological examination in the 3 groups evaluated. Microscopically, the polyethylene gel was surrounded by a thin pseudocapsule formation and minimal inflammatory cell response, which decreased from G1 to G2. Conclusion: The subcutaneous injection of polyethylene gel in rats elicited minimal local inflammatory response and no systemic side effects. Copyright © 2008 Informa Healthcare USA, Inc.

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.

Piezoelectric composite film for acoustic emission detection

The continuous technological advances require materials with properties that conventional material cannot display. Material property combinations are being the focus to the development of composite materials, which are considered a multiphase material that exhibits properties of the constituent phases. One interesting material to be studied as sensing material is the composite made of ferroelectric ceramic and polymeric matrix as a two-phases composite material. In that case, the combinations properties intended are the high piezo and pyroelectric activities of the dense ceramic with the impact resistance, flexibility, formability and low densities of the polymer. Using the piezoelectric property of the composite film, it can be used to detect acoustic emission (AE), which is a transient elastic wave generated by sudden deformation in materials under stress. AE can be applied for evaluating the health of structures in a nondestructive way and without any lapse of time. The preliminary result indicates that the composite Pz34/PEEK can be used as sensing material for nondestructive evaluation. ©2009 IEEE.