Influence of irrigation and intracanal dressing on the healing process of dogs' teeth with apical periodontitis.

Dogs' teeth with apical periodontitis were treated endodontically, Dakin's solution being used in an experimental group as the irrigation solution, and camphorated paramonochlorophenol as an intracanal dressing. For a second group of teeth, the irrigation solution used was physiologic saline, dry cotton only being placed into the pulpal chamber to take the place of an intracanal dressing. In a second visit, overinstrumentation and a new application of the same kind of dressing were performed, the root canals being then filled with gutta-percha cones and zinc oxide-eugenol cement. Other specimens were treated, in one visit, where physiologic saline or Dakin's solution were the irrigation solutions. The animals were sacrificed 6 months after the obturation of the root canals. Histologic exams showed better results for the experimental group where Dakin's solution and camphorated paramonochlorophenol had been used, with signs of repair characterized by newly formed cementum and bone tissue, as well as a marked reduction in size of the periapical lesions. No differences were seen in the results with physiologic saline or Dakin's solution as irrigants.

Experimentally induced anachoresis in the periapical region after root canal filling

Anachoresis is the phenomenon through which blood-borne bacteria, dyes, pigments and other materials are attracted and fixed to circumscribed areas of inflammation. This study evaluated the occurrence of anachoresis in the periapical region of dogs submitted to root canal fillings. One hundred and four roots from four dogs were endodontically treated and root canals were filled with zinc-oxide-eugenol cement. Fifty percent were filled up to the dentinocemental junction and the others were overfilled. At 120 days after root canal treatment, experimental bacteremia was induced by intravenous inoculation of 105 CFU Streptococcus pyogenes. The dogs were sacrificed 48 hours and 30 days after the bacteremia. Culture and DNA amplification by PCR revealed the presence of the inoculated bacteria just in periapical tissues of dogs sacrificed 48 hours after bacteremia and not in animals sacrificed after 30 days. AP-PCR fingerprints of recovered colonies of S. pyogenes and the presence of genetic markers of resistance to antimicrobials were similar to the inoculated strain. Endodontically treated periapices seemed to be prone to the occurrence of anachoresis and there was no relationship between the phenomenon and the level of root canal filling.

Sonochemical effects on ZnO particles

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

Desenvolvimento de procedimentos e métodos analíticos no campo forense aplicando os princípios da química verde

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos biológicos de nanopartículas de óxido de zinco: interação com proteínas e avaliação de “Burst” oxidativo de leucócitos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho da aplicação foliar de zinco em feijoeiro

The nutritional requirements of crops, in general, becomes more intense with the beginning of the reproductive phase, being more critical at the time of seed formation, when considerable amounts of nutrients are they translocation, this requirement should be increased to the fact that nutrients are essential to training and development of new bodies of booking. This study aimed to evaluate the agronomic efficiency of foliar application of zinc (zinc oxide Zn 700 g L-1 ) in bean plant, compared to leaf application of zinc sulphate (ZnSO4) and control (without application of Zn). The experiment was installed in the Faculty of Agricultural Sciences - UNESP / Campus de Botucatu-SP. Was placed in containers with a capacity of 20L of soil and leaf applications encompassing four schemes and two of rain, with 5 replicates per treatment, a total of 40 vessels. The results for the factorial design did not show in general, significantly different answers when evaluated on the simulation of rain or the lack of simulation. The treatment (700g L-1 of ZnO) has demonstrated agronomic efficiency as its foliar application, with results equal or exceed the application of ZnSO4 and control when applied at the same dose of Zn.

Incorporação de nanopartículas de óxido de zinco a um cimento de ionômero de vidro por meio da calcinação: avaliação de propriedades mecânicas e físicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Membranas de biocelulose como substrato para o crescimento de nanofios de ZnO: síntese e aplicação

Pós-graduação em Química - IQ

Membranas de biocelulose como substrato para o crescimento de nanofios de ZnO: síntese e aplicação

Pós-graduação em Química - IQ

Comparative degradation of ZnO- and SnO(2)-based polycrystalline non-ohmic devices by current pulse stress

The degradation behaviour of SnO(2)-based varistors (SCNCr) due to current pulses (8/20 mu s) is reported here for the first time in comparison with the ZnO-based commercial varistors (ZnO). Puncturing and/or cracking failures were observed in ZnO-based varistors possessing inferior thermo-mechanical properties in comparison with that found in a SCNCr system free of failures. Both systems presented electric degradation related to the increase in the leakage current and decrease in the electric breakdown field, non-linear coefficient and average value of the potential barrier height. However, it was found that a more severe degradation occurred in the ZnO-based varistors concerning their non-ohmic behaviour, while in the SCNCr system, a strong non-ohmic behaviour remained after the degradation. These results indicate that the degradation in the metal oxide varistors is controlled by a defect diffusion process whose rate depends on the mobility, the concentration of meta-stable defects and the amount of electrically active interfaces. The improved behaviour of the SCNCr system is then inferred to be associated with the higher amount of electrically active interfaces (85%) and to a higher energy necessary to activate the diffusion of the specific defects.

Diagnostic of Silicon Carbide Surge Arresters using Leakage Current Measurement

Nowadays, the zinc oxide surge arresters (ZnO) are widely used in power systems, however, a large number of silicon carbide surge arresters (SiC) are still in service in the utilities. On the other hand, it is not possible to replace all SiC surge arresters in a short time period, being necessary to review the maintenance program taking into account the surge arresters that are more degraded. In this context, a research project was established between the University of Sao Paulo and the electrical utility CTEEP, aiming the investigation of its SiC surge arresters. This work shows that the leakage current measurement, a diagnostic method for the ZnO surge arresters, can provide useful information related to the condition of the SiC surge arresters. Analysis of the amplitude and distortion of the leakage current, also considering thermovision measurements, resulted in better evaluation of the SiC surge arresters.

Electrocatalytic Activity of Platinum-Niobium Nanoparticles for Ethanol Oxidation

Three nanostructured platinum-niobium supported on Vulcan XC-72R carbon black materials were prepared as catalysts for the ethanol electroxidation: (i) deposition of platinum and niobium on Vulcan XC-72R carbon black, (ii) platinum decorated on a mixture of commercial amorphous Nb2O5/carbon black, and (iii) the same than ii but using crystalline Nb2O5, by reduction of the precursors with sodium borohydride in ethanol. All the catalysts showed platinum crystal sizes in the range of 3-4 nm, with no or little modification of the lattice parameter. The analyses of the electronic structure from the XANES region of the XAS spectra displayed some interactions between platinum and niobium, despite the niobium was primarily in the form of pentoxide in all the catalysts. CO stripping exhibited a promising low onset potential and a large current density, especially in the case of the deposited catalyst. Ethanol electroxidation experiments revealed that the Pt-Nb(2)O(5)crystalline/C generated the largest current. However it was not effective to completely oxidize ethanol, leading to acetic acid as the main product. In this sense, the highest efficiency for the complete oxidation of ethanol was obtained for the deposited catalyst. These results were interpreted in terms of the physico-chemical characteristic displayed by the different catalysts. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.040210jes] All rights reserved.

APTES-Modified RE2O3:Eu3+ Luminescent Beads: Structure and Properties

Europium-doped lanthanide oxide RE2O3:Eu3+ (RE = Y or Gd) luminescent beads, with a spherical shape and a diameter of 150 +/- 15 nm, have been modified by reaction with 3-aminopropyltriethoxysilane (APTES), in order to introduce reactive amine groups at their surfaces. The direct silanation has resulted in the formation of a nanometric layer at the surface of the beads, with an optimum grafting rate of 0.055 +/- 0.005 mol APTES/mol RE2O3. Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies confirmed the condensation of an organosilane layer, made of cross-linked -O-Si-O-Si- and of groups -O-Si-R (with R = (CH2)(3)NH2 or O-Et). Titration of the accessible amine groups has been performed by simultaneously measuring the luminescence of grafted fluorescein isothiocyanate and that of core particles: there are about 2.3 X 10(4) (2.8 X 10(4)) -NH2 per Y2O3:Eu3+ (Gd2O3:Eu3+) bead. The isoelectronic point was shifted by one pH unit after APTES modification. The surface modification by APTES at least preserved (for Gd2O3:Eu3+) or improved (for Y2O3:Eu3+) the red emission of the beads.

Platinum nanoparticles incorporated in silsesquioxane for use in LbL films for the simultaneous detection of dopamine and ascorbic acid

We describe the preparation of platinum nanoparticles (PtNPs) using the 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl-) as a nanoreactor and stabilizer. The formation of PtNPs was monitored by UV-Vis spectroscopy by measuring the decrease in the intensity of the band at 375 nm, which is attributed to the electronic absorption of PtCl62- ions. TEM images of Pt-SiPy+Cl- nanohybrid indicated an average size of 3-40 nm for PtNPs. The Pt-SiPy+Cl- was used as a polycation in the preparation of layer-by-layer films (LbL) on a glass substrate coated with fluorine-doped tin oxide (FTO) alternating with the polyanion poly(vinyl sulfonic acid) (PVS). The films were electrochemically tested in sulfuric acid to confirm the deposition of Pt-SiPy+Cl- onto the LbL films, observing the adsorption and desorption of hydrogen (E-pa = 0.1 V) and by the redox process of formation for PtO with E-pa = 1.3 V and E-pc = 0.65 V. FTIR and Raman spectra confirmed the presence of the PVS and Pt-SiPy+Cl- in the LbL films. A linear increase in the absorbance in the UV-Vis spectra of the Pt-SiPy+Cl- at 258 nm (pi -> pi* transition of the pyridine groups) with a number of Pt-SiPy+Cl-/PVS or PVS/SiPy+Cl- bilayers (R = 0.992) was observed. These LbL films were tested for the determination of dopamine (DA) in the presence of ascorbic acid (AA) with a detection limit (DL) on the order of 2.6 x 10(-6) mol L-1 and a quantification limit (QL) of 8.6 x 10(-6) mol L-1. The films exhibited a good repeatability and reproducibility, providing a potential difference of 550 mV for the oxidation of DA with AA interferent.

Rat subcutaneous tissue response to MTA Fillapex® and Portland cement

The aim of this study was to evaluate the response of rat subcutaneous tissue to MTA Fillapex® (Angelus), an experimental root canal filling material based on Portland cement and propylene glycol (PCPG), and a zinc oxide, eugenol and iodoform (ZOEI) paste. These materials were placed in polyethylene tubes and implanted into the dorsal connective tissue of Wistar rats for 7 and 15 days. The specimens were stained with hematoxylin and eosin, and evaluated regarding inflammatory reaction parameters by optical microscopy. The intensity of inflammatory response against the sealers was analyzed by two blinded and previously calibrated examiners for all experimental periods (kappa=0.96). The histological evaluation showed that all materials caused a moderate inflammatory reaction at 7 days, which subsided with time. A greater inflammatory reaction was observed at 7 days in the tubes filled with ZOEI paste. Tubes filled with MTA Fillapex presented some giant cells, macrophages and lymphocytes after 7 days. At 15 days, the presence of fibroblasts and collagen fibers was observed indicating normal tissue healing. The tubes filled with PCPG showed similar results to those observed in MTA Fillapex. At 15 days, the inflammatory reaction was almost absent at the tissue, with several collagen fibers indicating normal tissue healing. Data were analyzed by the nonparametric Kruskal-Wallis test (?=0.05). Statistically significant difference (p<0.05) was found only between PCPG at 15 days and ZOEI at 7 days groups. No significant differences were observed among the other groups/periods (p>0.05). MTA Fillapex and Portland cement added with propylene glycol had greater tissue compatibility than the PCPG paste.